read a single stream of data from a USB keyboard

weixin_38053367 2004-06-30 06:36:35

How can I read a single stream of data from a USB keyboard device (on Solaris 8, using C).

Many Thank's.

...全文

17 回复打赏收藏转发到动态举报

写回复

回复

切换为时间正序

请发表友善的回复…

发表回复

Computer Networking: A Top-Down Approach, 6th Edition Solutions to Review Questions and Problems Version Date: May 2012 This document contains the solutions to review questions and problems for the 5th edition of Computer Networking: A Top-Down Approach by Jim Kurose and Keith Ross. These solutions are being made available to instructors ONLY. Please do NOT copy or distribute this document to others (even other instructors). Please do not post any solutions on a publicly-available Web site. We’ll be happy to provide a copy (up-to-date) of this solution manual ourselves to anyone who asks. Acknowledgments: Over the years, several students and colleagues have helped us prepare this solutions manual. Special thanks goes to HongGang Zhang, Rakesh Kumar, Prithula Dhungel, and Vijay Annapureddy. Also thanks to all the readers who have made suggestions and corrected errors. All material © copyright 1996-2012 by J.F. Kurose and K.W. Ross. All rights reserved Chapter 1 Review Questions There is no difference. Throughout this text, the words “host” and “end system” are used interchangeably. End systems include PCs, workstations, Web servers, mail servers, PDAs, Internet-connected game consoles, etc. From Wikipedia: Diplomatic protocol is commonly described as a set of international courtesy rules. These well-established and time-honored rules have made it easier for nations and people to live and work together. Part of protocol has always been the acknowledgment of the hierarchical standing of all present. Protocol rules are based on the principles of civility. Standards are important for protocols so that people can create networking systems and products that interoperate. 1. Dial-up modem over telephone line: home; 2. DSL over telephone line: home or small office; 3. Cable to HFC: home; 4. 100 Mbps switched Ethernet: enterprise; 5. Wifi (802.11): home and enterprise: 6. 3G and 4G: wide-area wireless. HFC bandwidth is shared among the users. On the downstream channel, all packets emanate from a single source, namely, the head end. Thus, there are no collisions in the downstream channel. In most American cities, the current possibilities include: dial-up; DSL; cable modem; fiber-to-the-home. 7. Ethernet LANs have transmission rates of 10 Mbps, 100 Mbps, 1 Gbps and 10 Gbps. 8. Today, Ethernet most commonly runs over twisted-pair copper wire. It also can run over fibers optic links. 9. Dial up modems: up to 56 Kbps, bandwidth is dedicated; ADSL: up to 24 Mbps downstream and 2.5 Mbps upstream, bandwidth is dedicated; HFC, rates up to 42.8 Mbps and upstream rates of up to 30.7 Mbps, bandwidth is shared. FTTH: 2-10Mbps upload; 10-20 Mbps download; bandwidth is not shared. 10. There are two popular wireless Internet access technologies today: Wifi (802.11) In a wireless LAN, wireless users transmit/receive packets to/from an base station (i.e., wireless access point) within a radius of few tens of meters. The base station is typically connected to the wired Internet and thus serves to connect wireless users to the wired network. 3G and 4G wide-area wireless access networks. In these systems, packets are transmitted over the same wireless infrastructure used for cellular telephony, with the base station thus being managed by a telecommunications provider. This provides wireless access to users within a radius of tens of kilometers of the base station. 11. At time t0 the sending host begins to transmit. At time t1 = L/R1, the sending host completes transmission and the entire packet is received at the router (no propagation delay). Because the router has the entire packet at time t1, it can begin to transmit the packet to the receiving host at time t1. At time t2 = t1 + L/R2, the router completes transmission and the entire packet is received at the receiving host (again, no propagation delay). Thus, the end-to-end delay is L/R1 + L/R2. 12. A circuit-switched network can guarantee a certain amount of end-to-end bandwidth for the duration of a call. Most packet-switched networks today (including the Internet) cannot make any end-to-end guarantees for bandwidth. FDM requires sophisticated analog hardware to shift signal into appropriate frequency bands. 13. a) 2 users can be supported because each user requires half of the link bandwidth. b) Since each user requires 1Mbps when transmitting, if two or fewer users transmit simultaneously, a maximum of 2Mbps will be required. Since the available bandwidth of the shared link is 2Mbps, there will be no queuing delay before the link. Whereas, if three users transmit simultaneously, the bandwidth required will be 3Mbps which is more than the available bandwidth of the shared link. In this case, there will be queuing delay before the link. c) Probability that a given user is transmitting = 0.2 d) Probability that all three users are transmitting simultaneously = = (0.2)3 = 0.008. Since the queue grows when all the users are transmitting, the fraction of time during which the queue grows (which is equal to the probability that all three users are transmitting simultaneously) is 0.008. 14. If the two ISPs do not peer with each other, then when they send traffic to each other they have to send the traffic through a provider ISP (intermediary), to which they have to pay for carrying the traffic. By peering with each other directly, the two ISPs can reduce their payments to their provider ISPs. An Internet Exchange Points (IXP) (typically in a standalone building with its own switches) is a meeting point where multiple ISPs can connect and/or peer together. An ISP earns its money by charging each of the the ISPs that connect to the IXP a relatively small fee, which may depend on the amount of traffic sent to or received from the IXP. 15. Google's private network connects together all its data centers, big and small. Traffic between the Google data centers passes over its private network rather than over the public Internet. Many of these data centers are located in, or close to, lower tier ISPs. Therefore, when Google delivers content to a user, it often can bypass higher tier ISPs. What motivates content providers to create these networks? First, the content provider has more control over the user experience, since it has to use few intermediary ISPs. Second, it can save money by sending less traffic into provider networks. Third, if ISPs decide to charge more money to highly profitable content providers (in countries where net neutrality doesn't apply), the content providers can avoid these extra payments. 16. The delay components are processing delays, transmission delays, propagation delays, and queuing delays. All of these delays are fixed, except for the queuing delays, which are variable. 17. a) 1000 km, 1 Mbps, 100 bytes b) 100 km, 1 Mbps, 100 bytes 18. 10msec; d/s; no; no 19. a) 500 kbps b) 64 seconds c) 100kbps; 320 seconds 20. End system A breaks the large file into chunks. It adds header to each chunk, thereby generating multiple packets from the file. The header in each packet includes the IP address of the destination (end system B). The packet switch uses the destination IP address in the packet to determine the outgoing link. Asking which road to take is analogous to a packet asking which outgoing link it should be forwarded on, given the packet’s destination address. 21. The maximum emission rate is 500 packets/sec and the maximum transmission rate is 350 packets/sec. The corresponding traffic intensity is 500/350 =1.43 > 1. Loss will eventually occur for each experiment; but the time when loss first occurs will be different from one experiment to the next due to the randomness in the emission process. 22. Five generic tasks are error control, flow control, segmentation and reassembly, multiplexing, and connection setup. Yes, these tasks can be duplicated at different layers. For example, error control is often provided at more than one layer. 23. The five layers in the Internet protocol stack are – from top to bottom – the application layer, the transport layer, the network layer, the link layer, and the physical layer. The principal responsibilities are outlined in Section 1.5.1. 24. Application-layer message: data which an application wants to send and passed onto the transport layer; transport-layer segment: generated by the transport layer and encapsulates application-layer message with transport layer header; network-layer datagram: encapsulates transport-layer segment with a network-layer header; link-layer frame: encapsulates network-layer datagram with a link-layer header. 25. Routers process network, link and physical layers (layers 1 through 3). (This is a little bit of a white lie, as modern routers sometimes act as firewalls or caching components, and process Transport layer as well.) Link layer switches process link and physical layers (layers 1 through2). Hosts process all five layers. 26. a) Virus Requires some form of human interaction to spread. Classic example: E-mail viruses. b) Worms No user replication needed. Worm in infected host scans IP addresses and port numbers, looking for vulnerable processes to infect. 27. Creation of a botnet requires an attacker to find vulnerability in some application or system (e.g. exploiting the buffer overflow vulnerability that might exist in an application). After finding the vulnerability, the attacker needs to scan for hosts that are vulnerable. The target is basically to compromise a series of systems by exploiting that particular vulnerability. Any system that is part of the botnet can automatically scan its environment and propagate by exploiting the vulnerability. An important property of such botnets is that the originator of the botnet can remotely control and issue commands to all the nodes in the botnet. Hence, it becomes possible for the attacker to issue a command to all the nodes, that target a single node (for example, all nodes in the botnet might be commanded by the attacker to send a TCP SYN message to the target, which might result in a TCP SYN flood attack at the target). 28. Trudy can pretend to be Bob to Alice (and vice-versa) and partially or completely modify the message(s) being sent from Bob to Alice. For example, she can easily change the phrase “Alice, I owe you $1000” to “Alice, I owe you $10,000”. Furthermore, Trudy can even drop the packets that are being sent by Bob to Alice (and vise-versa), even if the packets from Bob to Alice are encrypted. Chapter 1 Problems Problem 1 There is no single right answer to this question. Many protocols would do the trick. Here's a simple answer below: Messages from ATM machine to Server Msg name purpose -------- ------- HELO Let server know that there is a card in the ATM machine ATM card transmits user ID to Server PASSWD User enters PIN, which is sent to server BALANCE User requests balance WITHDRAWL User asks to withdraw money BYE user all done Messages from Server to ATM machine (display) Msg name purpose -------- ------- PASSWD Ask user for PIN (password) OK last requested operation (PASSWD, WITHDRAWL) OK ERR last requested operation (PASSWD, WITHDRAWL) in ERROR AMOUNT sent in response to BALANCE request BYE user done, display welcome screen at ATM Correct operation: client server HELO (userid) --------------> (check if valid userid) <------------- PASSWD PASSWD --------------> (check password) <------------- AMOUNT WITHDRAWL --------------> check if enough $ to cover withdrawl (check if valid userid) <------------- PASSWD PASSWD --------------> (check password) <------------- AMOUNT WITHDRAWL --------------> check if enough $ to cover withdrawl <------------- BYE Problem 2 At time N*(L/R) the first packet has reached the destination, the second packet is stored in the last router, the third packet is stored in the next-to-last router, etc. At time N*(L/R) + L/R, the second packet has reached the destination, the third packet is stored in the last router, etc. Continuing with this logic, we see that at time N*(L/R) + (P-1)*(L/R) = (N+P-1)*(L/R) all packets have reached the destination. Problem 3 a) A circuit-switched network would be well suited to the application, because the application involves long sessions with predictable smooth bandwidth requirements. Since the transmission rate is known and not bursty, bandwidth can be reserved for each application session without significant waste. In addition, the overhead costs of setting up and tearing down connections are amortized over the lengthy duration of a typical application session. b) In the worst case, all the applications simultaneously transmit over one or more network links. However, since each link has sufficient bandwidth to handle the sum of all of the applications' data rates, no congestion (very little queuing) will occur. Given such generous link capacities, the network does not need congestion control mechanisms. Problem 4 Between the switch in the upper left and the switch in the upper right we can have 4 connections. Similarly we can have four connections between each of the 3 other pairs of adjacent switches. Thus, this network can support up to 16 connections. We can 4 connections passing through the switch in the upper-right-hand corner and another 4 connections passing through the switch in the lower-left-hand corner, giving a total of 8 connections. Yes. For the connections between A and C, we route two connections through B and two connections through D. For the connections between B and D, we route two connections through A and two connections through C. In this manner, there are at most 4 connections passing through any link. Problem 5 Tollbooths are 75 km apart, and the cars propagate at 100km/hr. A tollbooth services a car at a rate of one car every 12 seconds. a) There are ten cars. It takes 120 seconds, or 2 minutes, for the first tollbooth to service the 10 cars. Each of these cars has a propagation delay of 45 minutes (travel 75 km) before arriving at the second tollbooth. Thus, all the cars are lined up before the second tollbooth after 47 minutes. The whole process repeats itself for traveling between the second and third tollbooths. It also takes 2 minutes for the third tollbooth to service the 10 cars. Thus the total delay is 96 minutes. b) Delay between tollbooths is 8*12 seconds plus 45 minutes, i.e., 46 minutes and 36 seconds. The total delay is twice this amount plus 8*12 seconds, i.e., 94 minutes and 48 seconds. Problem 6 a) seconds. b) seconds. c) seconds. d) The bit is just leaving Host A. e) The first bit is in the link and has not reached Host B. f) The first bit has reached Host B. g) Want km. Problem 7 Consider the first bit in a packet. Before this bit can be transmitted, all of the bits in the packet must be generated. This requires sec=7msec. The time required to transmit the packet is sec= sec. Propagation delay = 10 msec. The delay until decoding is 7msec + sec + 10msec = 17.224msec A similar analysis shows that all bits experience a delay of 17.224 msec. Problem 8 a) 20 users can be supported. b) . c) . d) . We use the central limit theorem to approximate this probability. Let be independent random variables such that . “21 or more users” when is a standard normal r.v. Thus “21 or more users” . Problem 9 10,000 Problem 10 The first end system requires L/R1 to transmit the packet onto the first link; the packet propagates over the first link in d1/s1; the packet switch adds a processing delay of dproc; after receiving the entire packet, the packet switch connecting the first and the second link requires L/R2 to transmit the packet onto the second link; the packet propagates over the second link in d2/s2. Similarly, we can find the delay caused by the second switch and the third link: L/R3, dproc, and d3/s3. Adding these five delays gives dend-end = L/R1 + L/R2 + L/R3 + d1/s1 + d2/s2 + d3/s3+ dproc+ dproc To answer the second question, we simply plug the values into the equation to get 6 + 6 + 6 + 20+16 + 4 + 3 + 3 = 64 msec. Problem 11 Because bits are immediately transmitted, the packet switch does not introduce any delay; in particular, it does not introduce a transmission delay. Thus, dend-end = L/R + d1/s1 + d2/s2+ d3/s3 For the values in Problem 10, we get 6 + 20 + 16 + 4 = 46 msec. Problem 12 The arriving packet must first wait for the link to transmit 4.5 *1,500 bytes = 6,750 bytes or 54,000 bits. Since these bits are transmitted at 2 Mbps, the queuing delay is 27 msec. Generally, the queuing delay is (nL + (L - x))/R. Problem 13 The queuing delay is 0 for the first transmitted packet, L/R for the second transmitted packet, and generally, (n-1)L/R for the nth transmitted packet. Thus, the average delay for the N packets is: (L/R + 2L/R + ....... + (N-1)L/R)/N = L/(RN) * (1 + 2 + ..... + (N-1)) = L/(RN) * N(N-1)/2 = LN(N-1)/(2RN) = (N-1)L/(2R) Note that here we used the well-known fact: 1 + 2 + ....... + N = N(N+1)/2 It takes seconds to transmit the packets. Thus, the buffer is empty when a each batch of packets arrive. Thus, the average delay of a packet across all batches is the average delay within one batch, i.e., (N-1)L/2R. Problem 14 The transmission delay is . The total delay is Let . Total delay = For x=0, the total delay =0; as we increase x, total delay increases, approaching infinity as x approaches 1/a. Problem 15 Total delay . Problem 16 The total number of packets in the system includes those in the buffer and the packet that is being transmitted. So, N=10+1. Because , so (10+1)=a*(queuing delay + transmission delay). That is, 11=a*(0.01+1/100)=a*(0.01+0.01). Thus, a=550 packets/sec. Problem 17 There are nodes (the source host and the routers). Let denote the processing delay at the th node. Let be the transmission rate of the th link and let . Let be the propagation delay across the th link. Then . Let denote the average queuing delay at node . Then . Problem 18 On linux you can use the command traceroute www.targethost.com and in the Windows command prompt you can use tracert www.targethost.com In either case, you will get three delay measurements. For those three measurements you can calculate the mean and standard deviation. Repeat the experiment at different times of the day and comment on any changes. Here is an example solution: Traceroutes between San Diego Super Computer Center and www.poly.edu The average (mean) of the round-trip delays at each of the three hours is 71.18 ms, 71.38 ms and 71.55 ms, respectively. The standard deviations are 0.075 ms, 0.21 ms, 0.05 ms, respectively. In this example, the traceroutes have 12 routers in the path at each of the three hours. No, the paths didn’t change during any of the hours. Traceroute packets passed through four ISP networks from source to destination. Yes, in this experiment the largest delays occurred at peering interfaces between adjacent ISPs. Traceroutes from www.stella-net.net (France) to www.poly.edu (USA). The average round-trip delays at each of the three hours are 87.09 ms, 86.35 ms and 86.48 ms, respectively. The standard deviations are 0.53 ms, 0.18 ms, 0.23 ms, respectively. In this example, there are 11 routers in the path at each of the three hours. No, the paths didn’t change during any of the hours. Traceroute packets passed three ISP networks from source to destination. Yes, in this experiment the largest delays occurred at peering interfaces between adjacent ISPs. Problem 19 An example solution: Traceroutes from two different cities in France to New York City in United States In these traceroutes from two different cities in France to the same destination host in United States, seven links are in common including the transatlantic link. In this example of traceroutes from one city in France and from another city in Germany to the same host in United States, three links are in common including the transatlantic link. Traceroutes to two different cities in China from same host in United States Five links are common in the two traceroutes. The two traceroutes diverge before reaching China Problem 20 Throughput = min{Rs, Rc, R/M} Problem 21 If only use one path, the max throughput is given by: . If use all paths, the max throughput is given by . Problem 22 Probability of successfully receiving a packet is: ps= (1-p)N. The number of transmissions needed to be performed until the packet is successfully received by the client is a geometric random variable with success probability ps. Thus, the average number of transmissions needed is given by: 1/ps . Then, the average number of re-transmissions needed is given by: 1/ps -1. Problem 23 Let’s call the first packet A and call the second packet B. If the bottleneck link is the first link, then packet B is queued at the first link waiting for the transmission of packet A. So the packet inter-arrival time at the destination is simply L/Rs. If the second link is the bottleneck link and both packets are sent back to back, it must be true that the second packet arrives at the input queue of the second link before the second link finishes the transmission of the first packet. That is, L/Rs + L/Rs + dprop = L/Rs + dprop + L/Rc Thus, the minimum value of T is L/Rc  L/Rs . Problem 24 40 terabytes = 40 * 1012 * 8 bits. So, if using the dedicated link, it will take 40 * 1012 * 8 / (100 *106 ) =3200000 seconds = 37 days. But with FedEx overnight delivery, you can guarantee the data arrives in one day, and it should cost less than $100. Problem 25 160,000 bits 160,000 bits The bandwidth-delay product of a link is the maximum number of bits that can be in the link. the width of a bit = length of link / bandwidth-delay product, so 1 bit is 125 meters long, which is longer than a football field s/R Problem 26 s/R=20000km, then R=s/20000km= 2.5*108/(2*107)= 12.5 bps Problem 27 80,000,000 bits 800,000 bits, this is because that the maximum number of bits that will be in the link at any given time = min(bandwidth delay product, packet size) = 800,000 bits. .25 meters Problem 28 ttrans + tprop = 400 msec + 80 msec = 480 msec. 20 * (ttrans + 2 tprop) = 20*(20 msec + 80 msec) = 2 sec. Breaking up a file takes longer to transmit because each data packet and its corresponding acknowledgement packet add their own propagation delays. Problem 29 Recall geostationary satellite is 36,000 kilometers away from earth surface. 150 msec 1,500,000 bits 600,000,000 bits Problem 30 Let’s suppose the passenger and his/her bags correspond to the data unit arriving to the top of the protocol stack. When the passenger checks in, his/her bags are checked, and a tag is attached to the bags and ticket. This is additional information added in the Baggage layer if Figure 1.20 that allows the Baggage layer to implement the service or separating the passengers and baggage on the sending side, and then reuniting them (hopefully!) on the destination side. When a passenger then passes through security and additional stamp is often added to his/her ticket, indicating that the passenger has passed through a security check. This information is used to ensure (e.g., by later checks for the security information) secure transfer of people. Problem 31 Time to send message from source host to first packet switch = With store-and-forward switching, the total time to move message from source host to destination host = Time to send 1st packet from source host to first packet switch = . . Time at which 2nd packet is received at the first switch = time at which 1st packet is received at the second switch = Time at which 1st packet is received at the destination host = . After this, every 5msec one packet will be received; thus time at which last (800th) packet is received = . It can be seen that delay in using message segmentation is significantly less (almost 1/3rd). Without message segmentation, if bit errors are not tolerated, if there is a single bit error, the whole message has to be retransmitted (rather than a single packet). Without message segmentation, huge packets (containing HD videos, for example) are sent into the network. Routers have to accommodate these huge packets. Smaller packets have to queue behind enormous packets and suffer unfair delays. Packets have to be put in sequence at the destination. Message segmentation results in many smaller packets. Since header size is usually the same for all packets regardless of their size, with message segmentation the total amount of header bytes is more. Problem 32 Yes, the delays in the applet correspond to the delays in the Problem 31.The propagation delays affect the overall end-to-end delays both for packet switching and message switching equally. Problem 33 There are F/S packets. Each packet is S=80 bits. Time at which the last packet is received at the first router is sec. At this time, the first F/S-2 packets are at the destination, and the F/S-1 packet is at the second router. The last packet must then be transmitted by the first router and the second router, with each transmission taking sec. Thus delay in sending the whole file is To calculate the value of S which leads to the minimum delay, Problem 34 The circuit-switched telephone networks and the Internet are connected together at "gateways". When a Skype user (connected to the Internet) calls an ordinary telephone, a circuit is established between a gateway and the telephone user over the circuit switched network. The skype user's voice is sent in packets over the Internet to the gateway. At the gateway, the voice signal is reconstructed and then sent over the circuit. In the other direction, the voice signal is sent over the circuit switched network to the gateway. The gateway packetizes the voice signal and sends the voice packets to the Skype user. Chapter 2 Review Questions The Web: HTTP; file transfer: FTP; remote login: Telnet; e-mail: SMTP; BitTorrent file sharing: BitTorrent protocol Network architecture refers to the organization of the communication process into layers (e.g., the five-layer Internet architecture). Application architecture, on the other hand, is designed by an application developer and dictates the broad structure of the application (e.g., client-server or P2P). The process which initiates the communication is the client; the process that waits to be contacted is the server. No. In a P2P file-sharing application, the peer that is receiving a file is typically the client and the peer that is sending the file is typically the server. The IP address of the destination host and the port number of the socket in the destination process. You would use UDP. With UDP, the transaction can be completed in one roundtrip time (RTT) - the client sends the transaction request into a UDP socket, and the server sends the reply back to the client's UDP socket. With TCP, a minimum of two RTTs are needed - one to set-up the TCP connection, and another for the client to send the request, and for the server to send back the reply. One such example is remote word processing, for example, with Google docs. However, because Google docs runs over the Internet (using TCP), timing guarantees are not provided. a) Reliable data transfer TCP provides a reliable byte-stream between client and server but UDP does not. b) A guarantee that a certain value for throughput will be maintained Neither c) A guarantee that data will be delivered within a specified amount of time Neither d) Confidentiality (via encryption) Neither SSL operates at the application layer. The SSL socket takes unencrypted data from the application layer, encrypts it and then passes it to the TCP socket. If the application developer wants TCP to be enhanced with SSL, she has to include the SSL code in the application. A protocol uses handshaking if the two communicating entities first exchange control packets before sending data to each other. SMTP uses handshaking at the application layer whereas HTTP does not. The applications associated with those protocols require that all application data be received in the correct order and without gaps. TCP provides this service whereas UDP does not. When the user first visits the site, the server creates a unique identification number, creates an entry in its back-end database, and returns this identification number as a cookie number. This cookie number is stored on the user’s host and is managed by the browser. During each subsequent visit (and purchase), the browser sends the cookie number back to the site. Thus the site knows when this user (more precisely, this browser) is visiting the site. Web caching can bring the desired content “closer” to the user, possibly to the same LAN to which the user’s host is connected. Web caching can reduce the delay for all objects, even objects that are not cached, since caching reduces the traffic on links. Telnet is not available in Windows 7 by default. to make it available, go to Control Panel, Programs and Features, Turn Windows Features On or Off, Check Telnet client. To start Telnet, in Windows command prompt, issue the following command > telnet webserverver 80 where "webserver" is some webserver. After issuing the command, you have established a TCP connection between your client telnet program and the web server. Then type in an HTTP GET message. An example is given below: Since the index.html page in this web server was not modified since Fri, 18 May 2007 09:23:34 GMT, and the above commands were issued on Sat, 19 May 2007, the server returned "304 Not Modified". Note that the first 4 lines are the GET message and header lines inputed by the user, and the next 4 lines (starting from HTTP/1.1 304 Not Modified) is the response from the web server. FTP uses two parallel TCP connections, one connection for sending control information (such as a request to transfer a file) and another connection for actually transferring the file. Because the control information is not sent over the same connection that the file is sent over, FTP sends control information out of band. The message is first sent from Alice’s host to her mail server over HTTP. Alice’s mail server then sends the message to Bob’s mail server over SMTP. Bob then transfers the message from his mail server to his host over POP3. 17. Received: from 65.54.246.203 (EHLO bay0-omc3-s3.bay0.hotmail.com) (65.54.246.203) by mta419.mail.mud.yahoo.com with SMTP; Sat, 19 May 2007 16:53:51 -0700 Received: from hotmail.com ([65.55.135.106]) by bay0-omc3-s3.bay0.hotmail.com with Microsoft SMTPSVC(6.0.3790.2668); Sat, 19 May 2007 16:52:42 -0700 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Sat, 19 May 2007 16:52:41 -0700 Message-ID: Received: from 65.55.135.123 by by130fd.bay130.hotmail.msn.com with HTTP; Sat, 19 May 2007 23:52:36 GMT From: "prithula dhungel" To: prithula@yahoo.com Bcc: Subject: Test mail Date: Sat, 19 May 2007 23:52:36 +0000 Mime-Version: 1.0 Content-Type: Text/html; format=flowed Return-Path: prithuladhungel@hotmail.com Figure: A sample mail message header Received: This header field indicates the sequence in which the SMTP servers send and receive the mail message including the respective timestamps. In this example there are 4 “Received:” header lines. This means the mail message passed through 5 different SMTP servers before being delivered to the receiver’s mail box. The last (forth) “Received:” header indicates the mail message flow from the SMTP server of the sender to the second SMTP server in the chain of servers. The sender’s SMTP server is at address 65.55.135.123 and the second SMTP server in the chain is by130fd.bay130.hotmail.msn.com. The third “Received:” header indicates the mail message flow from the second SMTP server in the chain to the third server, and so on. Finally, the first “Received:” header indicates the flow of the mail messages from the forth SMTP server to the last SMTP server (i.e. the receiver’s mail server) in the chain. Message-id: The message has been given this number BAY130-F26D9E35BF59E0D18A819AFB9310@phx.gbl (by bay0-omc3-s3.bay0.hotmail.com. Message-id is a unique string assigned by the mail system when the message is first created. From: This indicates the email address of the sender of the mail. In the given example, the sender is “prithuladhungel@hotmail.com” To: This field indicates the email address of the receiver of the mail. In the example, the receiver is “prithula@yahoo.com” Subject: This gives the subject of the mail (if any specified by the sender). In the example, the subject specified by the sender is “Test mail” Date: The date and time when the mail was sent by the sender. In the example, the sender sent the mail on 19th May 2007, at time 23:52:36 GMT. Mime-version: MIME version used for the mail. In the example, it is 1.0. Content-type: The type of content in the body of the mail message. In the example, it is “text/html”. Return-Path: This specifies the email address to which the mail will be sent if the receiver of this mail wants to reply to the sender. This is also used by the sender’s mail server for bouncing back undeliverable mail messages of mailer-daemon error messages. In the example, the return path is “prithuladhungel@hotmail.com”. With download and delete, after a user retrieves its messages from a POP server, the messages are deleted. This poses a problem for the nomadic user, who may want to access the messages from many different machines (office PC, home PC, etc.). In the download and keep configuration, messages are not deleted after the user retrieves the messages. This can also be inconvenient, as each time the user retrieves the stored messages from a new machine, all of non-deleted messages will be transferred to the new machine (including very old messages). Yes an organization’s mail server and Web server can have the same alias for a host name. The MX record is used to map the mail server’s host name to its IP address. You should be able to see the sender's IP address for a user with an .edu email address. But you will not be able to see the sender's IP address if the user uses a gmail account. It is not necessary that Bob will also provide chunks to Alice. Alice has to be in the top 4 neighbors of Bob for Bob to send out chunks to her; this might not occur even if Alice provides chunks to Bob throughout a 30-second interval. Recall that in BitTorrent, a peer picks a random peer and optimistically unchokes the peer for a short period of time. Therefore, Alice will eventually be optimistically unchoked by one of her neighbors, during which time she will receive chunks from that neighbor. The overlay network in a P2P file sharing system consists of the nodes participating in the file sharing system and the logical links between the nodes. There is a logical link (an “edge” in graph theory terms) from node A to node B if there is a semi-permanent TCP connection between A and B. An overlay network does not include routers. Mesh DHT: The advantage is in order to a route a message to the peer (with ID) that is closest to the key, only one hop is required; the disadvantage is that each peer must track all other peers in the DHT. Circular DHT: the advantage is that each peer needs to track only a few other peers; the disadvantage is that O(N) hops are needed to route a message to the peer that is closest to the key. 25. File Distribution Instant Messaging Video Streaming Distributed Computing With the UDP server, there is no welcoming socket, and all data from different clients enters the server through this one socket. With the TCP server, there is a welcoming socket, and each time a client initiates a connection to the server, a new socket is created. Thus, to support n simultaneous connections, the server would need n+1 sockets. For the TCP application, as soon as the client is executed, it attempts to initiate a TCP connection with the server. If the TCP server is not running, then the client will fail to make a connection. For the UDP application, the client does not initiate connections (or attempt to communicate with the UDP server) immediately upon execution Chapter 2 Problems Problem 1 a) F b) T c) F d) F e) F Problem 2 Access control commands: USER, PASS, ACT, CWD, CDUP, SMNT, REIN, QUIT. Transfer parameter commands: PORT, PASV, TYPE STRU, MODE. Service commands: RETR, STOR, STOU, APPE, ALLO, REST, RNFR, RNTO, ABOR, DELE, RMD, MRD, PWD, LIST, NLST, SITE, SYST, STAT, HELP, NOOP. Problem 3 Application layer protocols: DNS and HTTP Transport layer protocols: UDP for DNS; TCP for HTTP Problem 4 The document request was http://gaia.cs.umass.edu/cs453/index.html. The Host : field indicates the server's name and /cs453/index.html indicates the file name. The browser is running HTTP version 1.1, as indicated just before the first pair. The browser is requesting a persistent connection, as indicated by the Connection: keep-alive. This is a trick question. This information is not contained in an HTTP message anywhere. So there is no way to tell this from looking at the exchange of HTTP messages alone. One would need information from the IP datagrams (that carried the TCP segment that carried the HTTP GET request) to answer this question. Mozilla/5.0. The browser type information is needed by the server to send different versions of the same object to different types of browsers. Problem 5 The status code of 200 and the phrase OK indicate that the server was able to locate the document successfully. The reply was provided on Tuesday, 07 Mar 2008 12:39:45 Greenwich Mean Time. The document index.html was last modified on Saturday 10 Dec 2005 18:27:46 GMT. There are 3874 bytes in the document being returned. The first five bytes of the returned document are : read an RFC). Sections 8.1.2 and 8.1.2.1 of the RFC indicate that either the client or the server can indicate to the other that it is going to close the persistent connection. It does so by including the connection-token "close" in the Connection-header field of the http request/reply. HTTP does not provide any encryption services. (From RFC 2616) “Clients that use persistent connections should limit the number of simultaneous connections that they maintain to a given server. A single-user client SHOULD NOT maintain more than 2 connections with any server or proxy.” Yes. (From RFC 2616) “A client might have started to send a new request at the same time that the server has decided to close the "idle" connection. From the server's point of view, the connection is being closed while it was idle, but from the client's point of view, a request is in progress.” Problem 7 The total amount of time to get the IP address is . Once the IP address is known, elapses to set up the TCP connection and another elapses to request and receive the small object. The total response time is Problem 8 . . Problem 9 The time to transmit an object of size L over a link or rate R is L/R. The average time is the average size of the object divided by R:  = (850,000 bits)/(15,000,000 bits/sec) = .0567 sec The traffic intensity on the link is given by =(16 requests/sec)(.0567 sec/request) = 0.907. Thus, the average access delay is (.0567 sec)/(1 - .907)  .6 seconds. The total average response time is therefore .6 sec + 3 sec = 3.6 sec. The traffic intensity on the access link is reduced by 60% since the 60% of the requests are satisfied within the institutional network. Thus the average access delay is (.0567 sec)/[1 – (.4)(.907)] = .089 seconds. The response time is approximately zero if the request is satisfied by the cache (which happens with probability .6); the average response time is .089 sec + 3 sec = 3.089 sec for cache misses (which happens 40% of the time). So the average response time is (.6)(0 sec) + (.4)(3.089 sec) = 1.24 seconds. Thus the average response time is reduced from 3.6 sec to 1.24 sec. Problem 10 Note that each downloaded object can be completely put into one data packet. Let Tp denote the one-way propagation delay between the client and the server. First consider parallel downloads using non-persistent connections. Parallel downloads would allow 10 connections to share the 150 bits/sec bandwidth, giving each just 15 bits/sec. Thus, the total time needed to receive all objects is given by: (200/150+Tp + 200/150 +Tp + 200/150+Tp + 100,000/150+ Tp ) + (200/(150/10)+Tp + 200/(150/10) +Tp + 200/(150/10)+Tp + 100,000/(150/10)+ Tp ) = 7377 + 8*Tp (seconds) Now consider a persistent HTTP connection. The total time needed is given by: (200/150+Tp + 200/150 +Tp + 200/150+Tp + 100,000/150+ Tp ) + 10*(200/150+Tp + 100,000/150+ Tp ) =7351 + 24*Tp (seconds) Assuming the speed of light is 300*106 m/sec, then Tp=10/(300*106)=0.03 microsec. Tp is therefore negligible compared with transmission delay. Thus, we see that persistent HTTP is not significantly faster (less than 1 percent) than the non-persistent case with parallel download. Problem 11 Yes, because Bob has more connections, he can get a larger share of the link bandwidth. Yes, Bob still needs to perform parallel downloads; otherwise he will get less bandwidth than the other four users. Problem 12 Server.py from socket import * serverPort=12000 serverSocket=socket(AF_INET,SOCK_STREAM) serverSocket.bind(('',serverPort)) serverSocket.listen(1) connectionSocket, addr = serverSocket.accept() while 1: sentence = connectionSocket.recv(1024) print 'From Server:', sentence, '\n' serverSocket.close() Problem 13 The MAIL FROM: in SMTP is a message from the SMTP client that identifies the sender of the mail message to the SMTP server. The From: on the mail message itself is NOT an SMTP message, but rather is just a line in the body of the mail message. Problem 14 SMTP uses a line containing only a period to mark the end of a message body. HTTP uses “Content-Length header field” to indicate the length of a message body. No, HTTP cannot use the method used by SMTP, because HTTP message could be binary data, whereas in SMTP, the message body must be in 7-bit ASCII format. Problem 15 MTA stands for Mail Transfer Agent. A host sends the message to an MTA. The message then follows a sequence of MTAs to reach the receiver’s mail reader. We see that this spam message follows a chain of MTAs. An honest MTA should report where it receives the message. Notice that in this message, “asusus-4b96 ([58.88.21.177])” does not report from where it received the email. Since we assume only the originator is dishonest, so “asusus-4b96 ([58.88.21.177])” must be the originator. Problem 16 UIDL abbreviates “unique-ID listing”. When a POP3 client issues the UIDL command, the server responds with the unique message ID for all of the messages present in the user's mailbox. This command is useful for “download and keep”. By maintaining a file that lists the messages retrieved during earlier sessions, the client can use the UIDL command to determine which messages on the server have already been seen. Problem 17 a) C: dele 1 C: retr 2 S: (blah blah … S: ………..blah) S: . C: dele 2 C: quit S: +OK POP3 server signing off b) C: retr 2 S: blah blah … S: ………..blah S: . C: quit S: +OK POP3 server signing off C: list S: 1 498 S: 2 912 S: . C: retr 1 S: blah ….. S: ….blah S: . C: retr 2 S: blah blah … S: ………..blah S: . C: quit S: +OK POP3 server signing off Problem 18 For a given input of domain name (such as ccn.com), IP address or network administrator name, the whois database can be used to locate the corresponding registrar, whois server, DNS server, and so on. NS4.YAHOO.COM from www.register.com; NS1.MSFT.NET from ww.register.com Local Domain: www.mindspring.com Web servers : www.mindspring.com 207.69.189.21, 207.69.189.22, 207.69.189.23, 207.69.189.24, 207.69.189.25, 207.69.189.26, 207.69.189.27, 207.69.189.28 Mail Servers : mx1.mindspring.com (207.69.189.217) mx2.mindspring.com (207.69.189.218) mx3.mindspring.com (207.69.189.219) mx4.mindspring.com (207.69.189.220) Name Servers: itchy.earthlink.net (207.69.188.196) scratchy.earthlink.net (207.69.188.197) www.yahoo.com Web Servers: www.yahoo.com (216.109.112.135, 66.94.234.13) Mail Servers: a.mx.mail.yahoo.com (209.191.118.103) b.mx.mail.yahoo.com (66.196.97.250) c.mx.mail.yahoo.com (68.142.237.182, 216.39.53.3) d.mx.mail.yahoo.com (216.39.53.2) e.mx.mail.yahoo.com (216.39.53.1) f.mx.mail.yahoo.com (209.191.88.247, 68.142.202.247) g.mx.mail.yahoo.com (209.191.88.239, 206.190.53.191) Name Servers: ns1.yahoo.com (66.218.71.63) ns2.yahoo.com (68.142.255.16) ns3.yahoo.com (217.12.4.104) ns4.yahoo.com (68.142.196.63) ns5.yahoo.com (216.109.116.17) ns8.yahoo.com (202.165.104.22) ns9.yahoo.com (202.160.176.146) www.hotmail.com Web Servers: www.hotmail.com (64.4.33.7, 64.4.32.7) Mail Servers: mx1.hotmail.com (65.54.245.8, 65.54.244.8, 65.54.244.136) mx2.hotmail.com (65.54.244.40, 65.54.244.168, 65.54.245.40) mx3.hotmail.com (65.54.244.72, 65.54.244.200, 65.54.245.72) mx4.hotmail.com (65.54.244.232, 65.54.245.104, 65.54.244.104) Name Servers: ns1.msft.net (207.68.160.190) ns2.msft.net (65.54.240.126) ns3.msft.net (213.199.161.77) ns4.msft.net (207.46.66.126) ns5.msft.net (65.55.238.126) d) The yahoo web server has multiple IP addresses www.yahoo.com (216.109.112.135, 66.94.234.13) e) The address range for Polytechnic University: 128.238.0.0 – 128.238.255.255 f) An attacker can use the whois database and nslookup tool to determine the IP address ranges, DNS server addresses, etc., for the target institution. By analyzing the source address of attack packets, the victim can use whois to obtain information about domain from which the attack is coming and possibly inform the administrators of the origin domain. Problem 19 The following delegation chain is used for gaia.cs.umass.edu a.root-servers.net E.GTLD-SERVERS.NET ns1.umass.edu(authoritative) First command: dig +norecurse @a.root-servers.net any gaia.cs.umass.edu ;; AUTHORITY SECTION: edu. 172800 IN NS E.GTLD-SERVERS.NET. edu. 172800 IN NS A.GTLD-SERVERS.NET. edu. 172800 IN NS G3.NSTLD.COM. edu. 172800 IN NS D.GTLD-SERVERS.NET. edu. 172800 IN NS H3.NSTLD.COM. edu. 172800 IN NS L3.NSTLD.COM. edu. 172800 IN NS M3.NSTLD.COM. edu. 172800 IN NS C.GTLD-SERVERS.NET. Among all returned edu DNS servers, we send a query to the first one. dig +norecurse @E.GTLD-SERVERS.NET any gaia.cs.umass.edu umass.edu. 172800 IN NS ns1.umass.edu. umass.edu. 172800 IN NS ns2.umass.edu. umass.edu. 172800 IN NS ns3.umass.edu. Among all three returned authoritative DNS servers, we send a query to the first one. dig +norecurse @ns1.umass.edu any gaia.cs.umass.edu gaia.cs.umass.edu. 21600 IN A 128.119.245.12 The answer for google.com could be: a.root-servers.net E.GTLD-SERVERS.NET ns1.google.com(authoritative) Problem 20 We can periodically take a snapshot of the DNS caches in the local DNS servers. The Web server that appears most frequently in the DNS caches is the most popular server. This is because if more users are interested in a Web server, then DNS requests for that server are more frequently sent by users. Thus, that Web server will appear in the DNS caches more frequently. For a complete measurement study, see: Craig E. Wills, Mikhail Mikhailov, Hao Shang “Inferring Relative Popularity of Internet Applications by Actively Querying DNS Caches”, in IMC'03, October 2729, 2003, Miami Beach, Florida, USA Problem 21 Yes, we can use dig to query that Web site in the local DNS server. For example, “dig cnn.com” will return the query time for finding cnn.com. If cnn.com was just accessed a couple of seconds ago, an entry for cnn.com is cached in the local DNS cache, so the query time is 0 msec. Otherwise, the query time is large. Problem 22 For calculating the minimum distribution time for client-server distribution, we use the following formula: Dcs = max {NF/us, F/dmin} Similarly, for calculating the minimum distribution time for P2P distribution, we use the following formula: Where, F = 15 Gbits = 15 * 1024 Mbits us = 30 Mbps dmin = di = 2 Mbps Note, 300Kbps = 300/1024 Mbps. Client Server N 10 100 1000 u 300 Kbps 7680 51200 512000 700 Kbps 7680 51200 512000 2 Mbps 7680 51200 512000 Peer to Peer N 10 100 1000 u 300 Kbps 7680 25904 47559 700 Kbps 7680 15616 21525 2 Mbps 7680 7680 7680 Problem 23 Consider a distribution scheme in which the server sends the file to each client, in parallel, at a rate of a rate of us/N. Note that this rate is less than each of the client’s download rate, since by assumption us/N ≤ dmin. Thus each client can also receive at rate us/N. Since each client receives at rate us/N, the time for each client to receive the entire file is F/( us/N) = NF/ us. Since all the clients receive the file in NF/ us, the overall distribution time is also NF/ us. Consider a distribution scheme in which the server sends the file to each client, in parallel, at a rate of dmin. Note that the aggregate rate, N dmin, is less than the server’s link rate us, since by assumption us/N ≥ dmin. Since each client receives at rate dmin, the time for each client to receive the entire file is F/ dmin. Since all the clients receive the file in this time, the overall distribution time is also F/ dmin. From Section 2.6 we know that DCS ≥ max {NF/us, F/dmin} (Equation 1) Suppose that us/N ≤ dmin. Then from Equation 1 we have DCS ≥ NF/us . But from (a) we have DCS ≤ NF/us . Combining these two gives: DCS = NF/us when us/N ≤ dmin. (Equation 2) We can similarly show that: DCS =F/dmin when us/N ≥ dmin (Equation 3). Combining Equation 2 and Equation 3 gives the desired result. Problem 24 Define u = u1 + u2 + ….. + uN. By assumption us <= (us + u)/N Equation 1 Divide the file into N parts, with the ith part having size (ui/u)F. The server transmits the ith part to peer i at rate ri = (ui/u)us. Note that r1 + r2 + ….. + rN = us, so that the aggregate server rate does not exceed the link rate of the server. Also have each peer i forward the bits it receives to each of the N-1 peers at rate ri. The aggregate forwarding rate by peer i is (N-1)ri. We have (N-1)ri = (N-1)(usui)/u = (us + u)/N Equation 2 Let ri = ui/(N-1) and rN+1 = (us – u/(N-1))/N In this distribution scheme, the file is broken into N+1 parts. The server sends bits from the ith part to the ith peer (i = 1, …., N) at rate ri. Each peer i forwards the bits arriving at rate ri to each of the other N-1 peers. Additionally, the server sends bits from the (N+1) st part at rate rN+1 to each of the N peers. The peers do not forward the bits from the (N+1)st part. The aggregate send rate of the server is r1+ …. + rN + N rN+1 = u/(N-1) + us – u/(N-1) = us Thus, the server’s send rate does not exceed its link rate. The aggregate send rate of peer i is (N-1)ri = ui Thus, each peer’s send rate does not exceed its link rate. In this distribution scheme, peer i receives bits at an aggregate rate of Thus each peer receives the file in NF/(us+u). (For simplicity, we neglected to specify the size of the file part for i = 1, …., N+1. We now provide that here. Let Δ = (us+u)/N be the distribution time. For i = 1, …, N, the ith file part is Fi = ri Δ bits. The (N+1)st file part is FN+1 = rN+1 Δ bits. It is straightforward to show that F1+ ….. + FN+1 = F.) The solution to this part is similar to that of 17 (c). We know from section 2.6 that Combining this with a) and b) gives the desired result. Problem 25 There are N nodes in the overlay network. There are N(N-1)/2 edges. Problem 26 Yes. His first claim is possible, as long as there are enough peers staying in the swarm for a long enough time. Bob can always receive data through optimistic unchoking by other peers. His second claim is also true. He can run a client on each host, let each client “free-ride,” and combine the collected chunks from the different hosts into a single file. He can even write a small scheduling program to make the different hosts ask for different chunks of the file. This is actually a kind of Sybil attack in P2P networks. Problem 27 Peer 3 learns that peer 5 has just left the system, so Peer 3 asks its first successor (Peer 4) for the identifier of its immediate successor (peer 8). Peer 3 will then make peer 8 its second successor. Problem 28 Peer 6 would first send peer 15 a message, saying “what will be peer 6’s predecessor and successor?” This message gets forwarded through the DHT until it reaches peer 5, who realizes that it will be 6’s predecessor and that its current successor, peer 8, will become 6’s successor. Next, peer 5 sends this predecessor and successor information back to 6. Peer 6 can now join the DHT by making peer 8 its successor and by notifying peer 5 that it should change its immediate successor to 6. Problem 29 For each key, we first calculate the distances (using d(k,p)) between itself and all peers, and then store the key in the peer that is closest to the key (that is, with smallest distance value). Problem 30 Yes, randomly assigning keys to peers does not consider the underlying network at all, so it very likely causes mismatches. Such mismatches may degrade the search performance. For example, consider a logical path p1 (consisting of only two logical links): ABC, where A and B are neighboring peers, and B and C are neighboring peers. Suppose that there is another logical path p2 from A to C (consisting of 3 logical links): ADEC. It might be the case that A and B are very far away physically (and separated by many routers), and B and C are very far away physically (and separated by many routers). But it may be the case that A, D, E, and C are all very close physically (and all separated by few routers). In other words, a shorter logical path may correspond to a much longer physical path. Problem 31 If you run TCPClient first, then the client will attempt to make a TCP connection with a non-existent server process. A TCP connection will not be made. UDPClient doesn't establish a TCP connection with the server. Thus, everything should work fine if you first run UDPClient, then run UDPServer, and then type some input into the keyboard. If you use different port numbers, then the client will attempt to establish a TCP connection with the wrong process or a non-existent process. Errors will occur. Problem 32 In the original program, UDPClient does not specify a port number when it creates the socket. In this case, the code lets the underlying operating system choose a port number. With the additional line, when UDPClient is executed, a UDP socket is created with port number 5432 . UDPServer needs to know the client port number so that it can send packets back to the correct client socket. Glancing at UDPServer, we see that the client port number is not “hard-wired” into the server code; instead, UDPServer determines the client port number by unraveling the datagram it receives from the client. Thus UDP server will work with any client port number, including 5432. UDPServer therefore does not need to be modified. Before: Client socket = x (chosen by OS) Server socket = 9876 After: Client socket = 5432 Problem 33 Yes, you can configure many browsers to open multiple simultaneous connections to a Web site. The advantage is that you will you potentially download the file faster. The disadvantage is that you may be hogging the bandwidth, thereby significantly slowing down the downloads of other users who are sharing the same physical links. Problem 34 For an application such as remote login (telnet and ssh), a byte-stream oriented protocol is very natural since there is no notion of message boundaries in the application. When a user types a character, we simply drop the character into the TCP connection. In other applications, we may be sending a series of messages that have inherent boundaries between them. For example, when one SMTP mail server sends another SMTP mail server several email messages back to back. Since TCP does not have a mechanism to indicate the boundaries, the application must add the indications itself, so that receiving side of the application can distinguish one message from the next. If each message were instead put into a distinct UDP segment, the receiving end would be able to distinguish the various messages without any indications added by the sending side of the application. Problem 35 To create a web server, we need to run web server software on a host. Many vendors sell web server software. However, the most popular web server software today is Apache, which is open source and free. Over the years it has been highly optimized by the open-source community. Problem 36 The key is the infohash, the value is an IP address that currently has the file designated by the infohash. Chapter 3 Review Questions Call this protocol Simple Transport Protocol (STP). At the sender side, STP accepts from the sending process a chunk of data not exceeding 1196 bytes, a destination host address, and a destination port number. STP adds a four-byte header to each chunk and puts the port number of the destination process in this header. STP then gives the destination host address and the resulting segment to the network layer. The network layer delivers the segment to STP at the destination host. STP then examines the port number in the segment, extracts the data from the segment, and passes the data to the process identified by the port number. The segment now has two header fields: a source port field and destination port field. At the sender side, STP accepts a chunk of data not exceeding 1192 bytes, a destination host address, a source port number, and a destination port number. STP creates a segment which contains the application data, source port number, and destination port number. It then gives the segment and the destination host address to the network layer. After receiving the segment, STP at the receiving host gives the application process the application data and the source port number. No, the transport layer does not have to do anything in the core; the transport layer “lives” in the end systems. For sending a letter, the family member is required to give the delegate the letter itself, the address of the destination house, and the name of the recipient. The delegate clearly writes the recipient’s name on the top of the letter. The delegate then puts the letter in an envelope and writes the address of the destination house on the envelope. The delegate then gives the letter to the planet’s mail service. At the receiving side, the delegate receives the letter from the mail service, takes the letter out of the envelope, and takes note of the recipient name written at the top of the letter. The delegate then gives the letter to the family member with this name. No, the mail service does not have to open the envelope; it only examines the address on the envelope. Source port number y and destination port number x. An application developer may not want its application to use TCP’s congestion control, which can throttle the application’s sending rate at times of congestion. Often, designers of IP telephony and IP videoconference applications choose to run their applications over UDP because they want to avoid TCP’s congestion control. Also, some applications do not need the reliable data transfer provided by TCP. Since most firewalls are configured to block UDP traffic, using TCP for video and voice traffic lets the traffic though the firewalls. Yes. The application developer can put reliable data transfer into the application layer protocol. This would require a significant amount of work and debugging, however. Yes, both segments will be directed to the same socket. For each received segment, at the socket interface, the operating system will provide the process with the IP addresses to determine the origins of the individual segments. For each persistent connection, the Web server creates a separate “connection socket”. Each connection socket is identified with a four-tuple: (source IP address, source port number, destination IP address, destination port number). When host C receives and IP datagram, it examines these four fields in the datagram/segment to determine to which socket it should pass the payload of the TCP segment. Thus, the requests from A and B pass through different sockets. The identifier for both of these sockets has 80 for the destination port; however, the identifiers for these sockets have different values for source IP addresses. Unlike UDP, when the transport layer passes a TCP segment’s payload to the application process, it does not specify the source IP address, as this is implicitly specified by the socket identifier. Sequence numbers are required for a receiver to find out whether an arriving packet contains new data or is a retransmission. To handle losses in the channel. If the ACK for a transmitted packet is not received within the duration of the timer for the packet, the packet (or its ACK or NACK) is assumed to have been lost. Hence, the packet is retransmitted. A timer would still be necessary in the protocol rdt 3.0. If the round trip time is known then the only advantage will be that, the sender knows for sure that either the packet or the ACK (or NACK) for the packet has been lost, as compared to the real scenario, where the ACK (or NACK) might still be on the way to the sender, after the timer expires. However, to detect the loss, for each packet, a timer of constant duration will still be necessary at the sender. The packet loss caused a time out after which all the five packets were retransmitted. Loss of an ACK didn’t trigger any retransmission as Go-Back-N uses cumulative acknowledgements. The sender was unable to send sixth packet as the send window size is fixed to 5. When the packet was lost, the received four packets were buffered the receiver. After the timeout, sender retransmitted the lost packet and receiver delivered the buffered packets to application in correct order. Duplicate ACK was sent by the receiver for the lost ACK. The sender was unable to send sixth packet as the send win

You are visitor as of October 17, 1996.The Art of Assembly Language ProgrammingForward Why Would Anyone Learn This Stuff?1 What's Wrong With Assembly Language2 What's Right With Assembly Language?3 Organization of This Text and Pedagogical Concerns4 Obtaining Program Source Listings and Other Materials in This TextSection One: Machine OrganizationArt of Assembly Language: Chapter OneChapter One - Data Representation1.0 - Chapter Overview1.1 - Numbering Systems1.1.1 - A Review of the Decimal System1.1.2 - The Binary Numbering System1.1.3 - Binary Formats1.2 - Data Organization1.2.1 - Bits1.2.2 - Nibbles1.2.3 - Bytes1.2.4 - Words1.2.5 - Double Words1.3 - The Hexadecimal Numbering System1.4 - Arithmetic Operations on Binary and Hexadecimal Numbers1.5 - Logical Operations on Bits1.6 - Logical Operations on Binary Numbers and Bit Strings1.7 - Signed and Unsigned Numbers1.8 - Sign and Zero Extension1.9 - Shifts and Rotates1.10 - Bit Fields and Packed Data1.11 - The ASCII Character Set1.12 Summary1.13 Laboratory Exercises1.13.1 Installing the Software1.13.2 Data Conversion Exercises1.13.3 Logical Operations Exercises1.13.4 Sign and Zero Extension Exercises1.13.5 Packed Data Exercises1.14 Questions1.15 Programming ProjectsChapter Two - Boolean Algebra2.0 - Chapter Overview2.1 - Boolean Algebra2.2 - Boolean Functions and Truth Tables2.3 - Algebraic Manipulation of Boolean Expressions2.4 - Canonical Forms2.5 - Simplification of Boolean Functions2.6 - What Does This Have To Do With Computers, Anyway?2.6.1 - Correspondence Between Electronic Circuits and Boolean Functions2.6.2 - Combinatorial Circuits2.6.3 - Sequential and Clocked Logic2.7 - Okay, What Does It Have To Do With Programming, Then?2.8 - Generic Boolean Functions2.9 Laboratory Exercises<

Version 1.7 ----------- - ADD: Delphi/CBuilder 10.2 Tokyo now supported. - ADD: Delphi/CBuilder 10.1 Berlin now supported. - ADD: Delphi/CBuilder 10 Seattle now supported. - ADD: Delphi/CBuilder XE8 now supported. - ADD: Delphi/CBuilder XE7 now supported. - ADD: Delphi/CBuilder XE6 now supported. - ADD: Delphi/CBuilder XE5 now supported. - ADD: Delphi/CBuilder XE4 now supported. - ADD: Delphi/CBuilder XE3 now supported. - ADD: Delphi/CBuilder XE2 now supported. - ADD: Delphi/CBuilder XE now supported. - ADD: Delphi/CBuilder 2010 now supported. - ADD: Delphi/CBuilder 2009 now supported. - ADD: New demo project FlexCADImport. - FIX: The height of the TFlexRegularPolygon object incorrectly changes with its rotation. - FIX: Added division by zero protect in method TFlexControl.MovePathSegment. - FIX: The background beyond docuemnt wasn't filled when TFlexPanel.DocClipping=True. - FIX: In "Windows ClearType" font rendering mode (OS Windows mode) the "garbage" pixels can appear from the right and from the bottom sides of the painted rectangle of the TFlexText object. - FIX: The result rectangle incorrectly calculated in the TFlexText.GetRefreshRect method. - FIX: Added FPaintCache.rcPaint cleanup in the TFlexPanel.WMPaint method. Now it is possible to define is the drawing take place via WMPaint or via the PaintTo direct call (if rcPaint contain non-empty rectangle then WMPaint in progress). - FIX: The TFlexPanel.FPaintCache field moved in the protected class section. Added rcPaint field in FPaintCache that represents drawing rectangle. - ADD: In the text prcise mode (TFlexText.Precise=True) takes into account the rotation angle (TFlexText.Angle). - FIX: Removed FG_NEWTEXTROTATE directive (the TFlexText Precise mode should be used instead). - FIX: The TFlexRegularPolygon object clones incorrectly drawed in case when TFlexRegularPolygon have alternative brush (gradient, texture). - ADD: Add TFlexPanel.InvalidateControl virtual method which calls from TFle

******************************************* ************ WPTOOLS 6 History ************ ********** http://www.wpcubed.com ********* **** Copyright (C) 2012 J. Ziersch and **** **** WPCubed GmbH, Munich, Germany ******** ******************************************* * - = bug fix * + = new feature * * = changed, expanded feature ******************************************* * IMPORTANT: Please edit file WPINC.INC to * activate WPREPORTER, WPSPELL, wPDF, TBX * and GraphicEx / PNGImage support! * Delphi 2009 and later as inbuilt PNGImage ******************************************* * THE MANUAL (PDF) AND REFERENCE (HLP,CHM) * ARE PROVIDED AS SEPERATE DOWNLOADS! ******************************************* ~~~~~~~~~~ Important Notes ~~~~~~~~~~~~ - With Delphi XE2 or XE3 it is possible to compile WPTools into a 64 bit applications. You need WPTools 6 PRO or WPTools 6 Premium for this. - Localization and Inch/CM selection see http://www.wpcubed.com/manuals/wp5man/index.html?localization.htm Also see demo\tasks\localization. There are the required XML files. - if flag wpDontAddExternalFontLeading is active in property FormatOptionsEx the text will be formatted more like WPTools4/MS-Word. You can alternatively set global variable WPDoNotAddExternalFontLeading := TRUE and select the Printer WYSIWYG mode: TWPRichText1.HeaderFooter.UpdateReformatMode(true) - The FormatOption wpDisableAutosizeTables can be required for good display of tables. wpNoMinimumCellPadding for narrow layout, too. - If you plan to use DBWPRichText please check http://www.wpcubed.com/forum/viewtopic.php?p=3456 - The reader/writer receive their options through "FormatStrings" please see list at http://www.wpcubed.com/manuals/formatstrings.htm - WPTools is configured using the file WPINC.INC, here WPREPORTER is activated and the optional WPShared, WPSPell and wPDF can be selected to be compiled into main WPTools package. - also see FAQ: http://www.wpcubed.com/forum/viewforum.php?f=15 - and support forum: http://www.wpcubed.com/forum/ - WPTools 6 PRO and PREMIUM will be compiled as Version 5 if $define "WP6" is not set ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We recommend to use TMS components to create modern user interfaces, toolbars and ribbons. 19.2.2013 - WPTools 6.29.1 - fix in rtf writing code to solve problem with merged cells - fix possible rangecheck error - fix problem with TextObject.LoadFromFile and Delphi XE3 * RTF reader now handles UNC file links which use "\\" in the path * the cursor was not painted if DoubleBuffered was set to true for the parent of the editor + WPTools Premium: Saves and loads \column * improved theming of TWPToolbar and TWPToolPanel + new event: OnPaintDesktopBackground. It can be used to draw the parent of the editor, for example if it is a TMS panel or pager control. Example: procedure TForm1.WPRichText1PaintDesktopBackground(Sender: TObject; Canvas: TCanvas; R: TRect); begin // This would paint the TWPRichText, too - but TWPRichText is locked for repaint during this event AdvOfficePager1.PaintTo(Canvas, -WPRichText1.Left, -WPRichText1.Top); end; - HighlightTextColor can now also be used if 2Pass Painting is used 21.12.2012 - WPTools 6.29 - images in RTF label were not painted when label was moved + added support for XE3 to WPTools STD edition * stream RTFvariables were not loaded from WPT format. They are loaded now. 9.11.2012 - WPTools 6.28 - Update to RTF reader to load landscape flag for sections better - when page mirror was used, after a page break the text indentation was sometimes wrong - hyphenation code was broken - workaround for word files which have space characters in table definitions 16.10.2012 - WPTools 6.27'' * some additions to the PRO edition for XE3 26.9.2012 - WPTools 6.27' * The PRO Version now supports Delphi XE3 3.8.2012 - WPTools 6.27 - fix for wrong display of tables with header and footer rows. Sometimes both were painted without any data. + to load old Hiedit templates as RTF code use the formatstring -HiEditFields. This will create merge fields for ALL fields. - NL sign was not shown right after CTRL+ENTER was pressed (requires ShowNL) - fix for rangecheck exception with paintpages array - fix for footer and page mirror - doubleclick word selection now stops at NL - Workaround for Windows Spooler problems - some images would get lost - sections use footer and header of previous section, not general - ASetBorder did change all border types 12.3.2012 - WPTools 6.25.4 * allows changing of column width in redonly editors. Can be switchoed off in EditOptions or set compiler define TOTALREADONLY + wpDisableSelectAll in EditOptionsEx2 * changed reformat/repaint after Undo/Redo - pro and premium: Due to a problem with precompiler cursoir selection did not work correctly 8.3.2012 - WPTools 6.25.3' - borders for paragraphs with multiple lines were not drawn correctly - change in DBWPRich.pas to use LoadFromString instead of Text - fix possible range check error - change in WPTbar.pas to use different default for BevelOuter - change in WPIOHTML to use default charattr of paragraph is a paragraph is empty 9.2.2012 - WPTools 6.25.2 * new 2-pass painting triggers CustomPaint event only on second loop (when the text is painted) * changed protection of empty paragraph to WPTools 5 way + inside of the OnPrepareImageForSaving event it is now possible to set Writer.CurrentImageName to the name of the file which should be saved. This is only useful if ObjRef = nil and so no ObjRef.Filename can be set. + TParagraph.GetSubText now has optional parameter to disable the object reference char codes #1, #2 and #3 * HTML writer ignores #13 codes when writing the text. * additional savety code in HTML writer * HTML reader sets image width and height to contents, (if possible) * HTML reader: changes UTF8 handling for UTF8Sequence=1 * HTML reader does not stop on \0 anymore * HTML writer writes img tag also for empty images IF a name is provided in event PrepareImageforSaving * HTML reader does not add space at end anymore - the UNICODE reader uses attribute of current paragraph. This is important for consistent behaviour between ANSI and UNICODE version - when writing HTML background color is not set to white when shading is 0. 0 is treated as default value. - image align center and right now works in HTML - fix an endless loop when image was too large - improvement of table border drawing - improvement for right align in table cells + numbering will be used when wpFormatAsWebpage was set in AsWebpage 10.1.2012 - WPTools 6.25 + HTML reader reads cell heighs - RTF writer writes background color easier to understand by Word * improved XML reader/writer (unit WPIOXml1) * improved word wise cursor movement when fields are used + new "paint attributes" mode. Use WPRichText1.BrushStart to select this mode. - dashes were not painted using the current font color - some stability improvements 7.11.2011 - WPTools 6.22 + procedure TParagraph.CellSelectionAdd; + procedure CellSelectionRemove; + EditOptionsEx2: wpCellMultiSelect - allows multiselection in tables when CTRL is pressed + improved XML import/export (unit WPIOXML1.PAS) - some smaller bugs fixed 3.11.2011 - WPTools 6.21.2 - fix problem with TWPToolButton - improved HTML writer to write parameters in "" - improved display of arabic text 24.10.2011 - WPTools 6.21.1 - fix problem when painting insertpoints after tab stops. They were painted two times. - fix in XML and HTML writer. Close tags when extracting text from fields 19.10.2011 - WPTools 6.21 + CodeLocate can now also accessed in non-visual TWPRTFDataCollection and not just TWPCustomRtfEdit + CodeSelect can now also accessed in non-visual TWPRTFDataCollection and not just TWPCustomRtfEdit + TWPRTFDataCollection.CodeLocatePair( FormatName : String; var spar, epar : TParagraph; var spos, epos, : Integer ) :Integer; - solves problem with integrated Bin64 decoder + DeleteField now has optional "Contents" parameter to delete a certain field with contents + the text writer now understand the option -softlinebreaks to create a \n at the end of every line. In fact all soft line breaks will be handled like the #10 code. + CodeLoadSaveEmbeddedText - load or save text in fields, bookmarks, hyperlinks + the regular save and load methods (LoadFromFile, SaveToFile) can now access text wrapped by paired objects. specify the fieldname in the format string, i.e. "f:name=RTF" to save or load the contents of the field "name". + There is an overloaded LoadFromString which expects a WideString as parameter (Delphi 6+) - The Setup named the Delphi 2009 files "Delphi 2005" due to a typo. (Delphi 2005 units are not included anymore) - fix probable range check error in WPRTEDEFS 13.10.2011 - WPTools 6.20 + completely new setup procedure. The PRO and Premium releases don't include object files which makes them much smaller. * compiled new WPTools 6 Reference (CHM file) * Delphi XE2: several small changes to improve theming support * Delphi XE2: several small changes to provide compatibilty to 64bit compiler (requires WPTools PRO) + new demo developed with Delphi XE2, showcases actions, splitscreen, simulated MDI and property dialogs (Demos\XE2\WPWord) + wpDeleteAtEOFRemovesSpaceAfter in EditOptionsEx2 - TextObjectsGetList did not work * WPRuler uses Delphi XE2 VCL Theme plus * added defaults to properties TWPRichText - change in RTF reader to let section inherit the default layout, not the current page layout - fix of problem with table borders when also PageMirror was used. * change to DeleteMarkedChar. It now has additional parameter DeleteEmptyParAndTables : Boolean * change in unit WPWordConv to handle RTF as DOC files if they do not start with "{\rtf" * updated border dialog TWPParagraphBorderDlgEx * updated border drawing code - now supports dotted lines with wider lines. * modified method DeleteColumn * modified WPT reading code to repair table width which were negative + improved image rendering code for transparent (PNG) images. They will be drawn transparently also when scaled and also in high resolution rendering mode. + new code to draw dotted lines which also supports wider lines + new function WPReplaceTokens (unit WPUtils.PAS). It is a ReplaceTokens function to be used on a TWPRTFDataCollection, not TWPRichText - WPPremium - fix problem when there were too columns * MergeText now restores before Merge Cursor position and selection (except for cell selection) * resizing a table column does not move the cursor to the nearby cell anymore * different frame line when resizing columns and rows + InsertColumn now also works if wpAllowSplitOfCombinedCellsOnly was used in EditOptionsEx + new event OnPaintTextFrameRect let you paint background and borders for text frames, i.e. the text body or, with WPTools Premium, custom frames. + WPPREMIUM: In OnMeasureTextPage it is possible to set columns for certain pages. Using PageInfo.colflags=1 it is possible to activate a line between the columns It is also possible to add custom frames using PageInfo.rtfpage.AddFrameRect. + new ViewOptionEx: wpHideParBordersBeforAndAfterPageBreaks + improved paint routine now avoids clipping of characters which were overlapping their bounding box, such as italic letters or "f". The improvement is especially visible when selecting text or using character background colors + WPPREMIUM: it is now possible to print a line between columns using wpShowColumnCenterLine in ViewOptionsEx + With WPTools Premium it is now possible to print a line between certain colums - use par.ASet(WPAT_COLFLAGS, WPCOLUM_LINE); + paragraph styles can now contain border definion for paragraphs + TWPTextObjList now has a IndexOfSource function and a Source[] string array to access the objects * revised code to draw double borders - always draws twou lines on screen even when zoomed * improved saving of numbering attributes with styles * style dialog can now apply number level even if style does not have numbering yet. * revised wpNoEditOutsideTable - was not checked for keyboard input * fix problem with - - - - - at end of line - fix problem with spell-as-you go after hyperlinks - fix problem with page numbers in sections when tables were spanning pages - fix problem with right aligned negative numbers in merge fields * automatic text attribute was not inherited to tables inserted in fields * images with mode "under text " can now be also clicked at positiones where there is no text. - WPLngCtr now defines DONT_OVERRIDE_COM, that fixes the IDE problem with DevExpress Toolbar controls 18.7.2011 - WPTools 6.16.2 * ObjectMode wpobjPositionAtCenter can be used to aligh character based images to the center line. (Other RTF reader will not understand this feature) * some changes to prepare 64bit compatibility (requires WPTools 6 PRO) 7.7.2011 - WPTools 6.16.1 * change to avoid flickering when doing auto scroll * message strings are now loaded from resource strings - modified DBCS support for RTF reader * outerborder action now works for sinle cells and paragraphs 15.6.2011 - WPTools 6.16 + Many improvements to new Border Dialog. It is now possible to apply borders and colors to odd and even rows only. * RTF reader defines symbol IGNORE_AUTOWIDTH_TBL. This disable the Word2010 auto width columns which are not read correctly. Reason: Word 2010 seem to always add an empty column to the end. + using WPRichText1.Caret.Blink:=true it is possible to activate the blinking caret (0.5sec interval). * updated actions to apply inner and outer borders to selected cells * update to ExSymbolDialog, Tab and Table dialog - improved WPTOOLS reader to read and apply outline properties to current outline setting (unless wpLoadDoesNotOverride is used) - wpsec_ResetPageNumber flag is now saved in WPTOOLS format * tripple click in margin selects paragraph + double click in margin selects current cell + tripple click in margin selects current row - change for PaintEngine and TWPRichTextLabel to not shrink tables which are small enough to fit the page This solves a problem with dissapearing text in WPRichTextLabel - fix selection problem when several images were linked to same paragraph - when moving images the Z order will not be reset - HTML Writer: A style with name "DIV" will be added to the style sheet to save the default font - HTML Writer: BaseFont tag will now be written with font size (requires -writebasefont option) - improved display of character background color for fields and other special code - Saving a style sheet did not work with Unicode Compiler 8.5.2011 - WPTools 6.15 * updated border painting * updated Inner/Outer Border Action * new object sizing routine lets the user make the size larger than the page - update in WPTools reader to overwrite outline styles when loading tzhe same group 9.3.2011 - WPTools 6.14.6 * change in format routine to fix problem when a nested table cell caused a page break. 14.12.2010 - WPTools 6.14 * fix for SetAsString code (Unicode Delphi) * several fixes and updates in editor * WPTools Premium: $define DONT_AUTOENTER_TEXTBOXES in WPINC.INC to switch of the behavior, that when editing a textbox the user can click on any other and edit that. 22.9.2010 - WPTools 6.13.3 * WPCtrMemo.PAS now defines TEXT_IS_UNICODE fro Delphi 2009 and later. Now the property Text and SelText reads and writes unicode strigs * change in RTF reader to read ANSI characters in the range 128..255 * Tables and rows can now be hidden. (TParagraph.Hidden) * The Lines property now supports unicode strings (Delphi 2009 and later) + HTML reader and writer now use the entitly as soft hyphen 27.8.2010 - WPTools 6.13.2a + new ViewOptionEx wpUnderlineWebLinks. If active links like http://www.wptools.de will be drawn using the attributes for hyperlinks The HyperlinkCursor will be selected and the hyperlink event will be triggered * other fixes in RTF engine - Memo._OverrideCharset was not set to -1 27.7.2010 - WPTools 6.13.1 + WPRichText1.Memo.ColorGridLines can be used to change the color of the grid lines (ViewOptions) 23.7.2010 - WPTools 6.13 * several improvements of editor * improvement to RTF writer to when writing table cells * improved right aligned text * fixed problem with line heights of lines which are empty except for new line character 22.6.2010 - WPTools 6.12.1b - fix for problem when pressing Accent + Backspace - fix for WPReporter to assign default attribute to destination - fix for WPReporter to move images when converting templates 18.6.2010 - WPTools 6.12.1a * the new border dialog now reads the current border attributes from table cells, tables or selections - Premium: fix problem when loading columns which started on first line - fix in wpfUseKerning mode (FormatOptionsEx2) - it did not work as expected with some texts (We recommend to use wpfUseKerning - it produces better print quality on screen) * Pasting of HTML now works better - fix for right tabs when also borders were used 13.6.2010 - WPTools 6.12 + all new, powerful yet intuitive Border dialog. The border dialog can modify a range of selected cells, columns, rows, tables and also only modify certain properties while leaving the others unchanged. You need to activate the compiler symbol NEWBORDER to use it by default + new method: procedure SetBorderProperties(Inner, Outer: TWPTextStyle; ApplyMode : TWPParagraphBordApply; Mode : TWPUpdateBorderProperties = [wpSetBorderFlags, wpSetBorderType, wpSetBorderWidth, wpSetBorderColor, wpSetParColor, wpSetParShading]); This method is mainly used by the new border dialog. + new flags in ViewOptionsEx: wpShowCurrentCellAsSelected, // Displays current cell to be selected. Disables current selection wpShowCurrentRowAsSelected, // Displays current table row to be selected. Disables current selection wpShowCurrentTableAsSelected // Displays current table to be selected. Disables current selection + new property YOffsetNormal to defined an upper border for normal and wordwrap view. * feature Header.MarginMirror changed to work like MS Word new flag: wpMarginMirrorBookPrint in FormatOptionsEx2 to enable the previous logic * workaround for MouseWheel UP beeing triggered too often (10 mms check) + ClipboardOption wpcoDontPasteHTML to disable HTML pasting completely (avoid problems with firefox) + it is now possible to load base64 embedded JPEGs from HTML * it is now possible to change width of tables which exceed right margin - fix bug in HTML writer for lists in table cells - fix in RTF writer to write character colors also for text which is using a character style - fix: numbering was not always updated - fix: better use fonts in certain RTF files written by MS Word + Update to WPLanguageControl to make Localization easier to use. Only< this code is not required: procedure TForm1.WPLanguageControl1Loaded(Sender: TObject); begin WPLangInterface := TWPLocalizationInterface.Create(WPLanguageControl1); WPLocalizeAllStrings; end; 6.5.2010 - WPTools 6.11.2 * improvement to border rendering * improvement to XML unit WPIOXML1 (Premium) 5.5.2010 - WPTools 6.11.1 + ConvertTableToText now supports option to also handle soft line breaks - fix problems with underlines at end of line - fix problem when loading hyperlinks in RTF - fix problem when saving attributes to XML (WPTools Premium) - fix problem with text rendering - fix problem with tables which habe header row and pages with different header margin 19.4.2010 - WPTools 6.11 + EditOptionEx: wpRowMultiSelect + new event: OnInternPaintPar + new event: RTFDataCollection AfterApplyUndoObject 14.4.2010 - WPTools 6.10.6 * fields are now passed as unicode strings to PDF exporter * Delphi 2010/2009 import has been improved to load unicode values which are stroed in fields. 5.4.2010 - WPTools 6.10.5 + flag: wpDontExtendSelectionToRightMargin. Do not extend selection to end of line + wpInvertActiveRow in ViewOptionsEx - some fixes for Delphi 2009 and Delphi 2010 - fix for section support - WPTools premium: Fix for images in text boxes - workwaround to load RTF which use emfblib for pngblib 28.2.2010 - WPTools 6.10 - improve word left/right movement to skip hidden text - improve http load of images - improve support for numbering - improve saving of character style attributes 11.2.2010 - WPTools 6.09.1 + LoadFromString now has a "WithClear" parameter - fix in RTF reader to better load files which do not define codepage - fix in paint routine to solve a rare lockup - fix in format routine to improve section support 6.2.2010 - WPTools 6.09.1 - fix of problem in save routine when footnotes were used (WPTools premium) - fix in HTML writer - Image optiions now have a Rotation property which allows 90, 180 and 270 setting. - HTML reader and writer now support different colors for left,right,top, bottom lines 1.2.2010 - WPTools 6.09 - HTML writer will write 8 hard spaces for TAB stops at the start of a paragraph - HTML writer will write page information only if -PageInfo was used in format string - fix problem with left aligned text and image wrap around (wrong alignment) - fix problem with sometimes duplicated images in PDF export - fix problem with black rectangle in first line under Windows 7, 64 bit - Improvment to RTF reader to ignore section properties which are not followed by \sect 14.12.2009 - WPTools 6.08 - graphics are resized to fill text area - fixed problems in numbering - fixed problem with one word paragraphs in justified paragraphs - other improvements in editor 27.10.2009 - WPTools 6.07 - fixed one leaking TList per TWPRichText * improved layout of most important dialogs * improved extended insert symbol dialog - fix in RTF reader to load sections and header+footer written by Word 2003 - don't add unwanted cell padding when loading table cells - fix in WPTools reader to read custom number styles - if paragraph styles use number styles the indent defined in the style has priority over numberstyle - LabelDef now also works for one row and one column - better handling of mousewheel event - fix for tabs in tables + GIF animation (requires GifImage) library (not threaded) to use it You need to set ViewOption wpUseOwnDoubleBuffer and call the method RefreshAniImages using a timer object. - fix problem when sections were used with LabeDef.Active = true * change in HTML writer to close tags before paragraph end 4.10.2009 - WPTools 6.06 - fix problem with Delphi 2010 support (language control) - fix problem with PDF export to reduce PDF size - improve support for IME * improve AsWebPage format mode. Now WordWrap propery is supported. - fix searching text upwards with "Whole Word" selected + RTF writer now can use format option "-writehighlight" to writh \highlight instead of \cb 14.9.2009 - WPTools 6.05.9 + added Delphi 2010 Support - problem when pasting from "The Bat" - fix problem in Delphi 2009 (Assign Method) 3.8.2009 - WPTools 6.05.8' * when using "Delete All" in the tabstop dialog, all tabs will be cleared added to manual: Tabstop Category - fixed problem when deleting text in a paragraph. The alignment was cleared unexpectedly. - fix problem with installer, WPMangeHeaderFooter.DFM was not included - fix for IPara in mail merge field objects - improved handling of hoover effect for hyperlinks - improved text rendering for wPDF output (CID Mode) - add correct WPManHeadFoot.dfm 23.7.2009 - WPTools 6.05.7 + WRITE_PROP_WPTOOLSOBJ $define in WPIOWriteRTF. Avoid problems when saving RTF and opting in Word In case of special objects, such as SPAN codes, \*\wpfldinst is beeing written what is ignored by WOrd + Dialog HeaderFooter can optionally create and manage header&footer for the current section + new KeepN Handling. This is by default activated in FormatOptionsEx2 + new wpfHideParagraphWithHiddenText in FormatOptionsEx2. Now paragraphs will be hidden if empty or only contain hidden text. + new format option -zap1 will remove the every first byte to convert a two byte stream into singly byte -zap2 will remove every second byte. Usie this option when loading data from unicode data sets - bugfix for table loading in RTF 15.7.2009 - WPTools 6.05 + TParagraph.Trim method to remove white spaces at start and end + Vertical Scrolling by pressing the middle mouse button now works. + improved auto thumbnail mode * enhancement to HTML reader / writer to handle embedded SPAN objects + new method: ApplySPANStyles(and_remove : Boolean=false; ignore_charattr : Boolean = false); can be used to apply SPAN styles to the text which it embeds + The function InputSpanObjects( Attributes : TWPAbstractCharAttrInterface ) : TWPTextObj; can be used to wrap the selected text into SPAN objects + method LoadCSSheet can be used to load paragraph styles in CSS format from a string - fix problem with Wordrwap and centered text + new even OnTextObjectMovePosition (move event) - OnTextObjectMove is still used for resize (unchanged) 28.6.2009 - WPTools 6.04 + WPTools Premium: Column Balancing * many improvements in RTF reader. Word documents are now understood better * Improvement in check for protected text (ppMergedText) + new ViewOptionsEx property - auto hyperlinks were not working + TWPComboBox has an event OnUpdateItems which will be triggered after the items had been automatically assigned. 24.6.2009 - WPTools 6.03.6 * thinner page borders in thumbnail mode. ViewOptionsEx: wpAutoThumbnailMode will show pagenumbers only when in thubmbnail mode (= wpShowPageNRinGap in ViewOptions) + property ColorDesktop and DeskGradientHorizontal to render the background with a gradient fill * fix for protected text handling (CR after a field) * fix for text alignment near a movable image - EditOption AutoDetectHyperlinks was not working anymore * WPReporter: SuperMerge.Stack.PageBreakAFterGroup := true was ot working when footers were used 1.6.2009 - WPTools 6.03.5 - fix problem with display of character attributes when attributes were inherited from paragraph styles - fix problems with selection deletion in single column, single row tables - improvement of RTF writer when writing sections 11.5.2009 - WPTools 6.03.3 - improved report band dialog, new ShowOptions property - fix in RTF reader to load header/footer - change in HTML writer to save SPAN instead of FONT tag - several fixes in editor * WPTools Premium: better column support. Fixed column height now splits correctly on 2 pages. 28.4.2009 - WPTools 6.03.2 - fix problem with justified text in PDF 21.4.2009 - WPTools 6.03.1 - fix problem with images when used in Delphi 2009 - better support for header/footer in RTF files created by word. (Ignore bogus header/footer) - soome stability fixes 25.3.2009 - WPTools 6.03 + improved text rendering - optimation for character distances on screen to provide better display + improvement on ShowMergeFieldNames to improve cursor movement and drag and drop + automatic disable dragging of fields inside of fields + improved merge field selection. TextObject.SelectedObject now returns the mergefield if it was completely selected + change in HTML saving code to save src in after width adn height (for outlook) * various bugfixes 17.1.2009 - WPTools 6.02 - WPPREMIUM: Text after Columns initialized with WPAT_COLUMNS_Y is now allowed + TWPToolBar FontName drop down now lists fonts used by document first - fix for tables which use a fixed row height and are splitted on different pages + improvements necessary for Delphi 2009 - the Locaization demo now works + EditOptionEx wpDontPreserveObjectsAgainstDeletion - fix problem in ImageObject LoadFromStream when GraphicEx is used - fix problem with Delphi 2009 when loading WPReporter templates - fix problem with HTML reader with paragraph style of first paragraph + GetFontUnicodeRanges dynamically linked to avoid Win98 problem 26.10.2008 - WPTools 6.01 * updated HTTP Demo, now with "Source View" + DELETE/BACKSPC at start of line removes right/center alignment + loads background images for paragraphs, tables and styles * improvement to text protection (empty lines) - improvements to HTML and CSS reader - improved HTML format routine - improved MIME loading - now supports binary data despite Synapse does not) + MIME reader capturesHTML body for SourceVIew * DataProvider now uses MergeText('',true) instead of MergeText + boolean wphttp_Disable to disconnect HTTP temporarily * several changes to improve compatibility with Delphi 2009 17.10.2008 - WPTools 6.00.1 - several changes to fix problems which occured with use of Delphi 2009 * update to WPIO_MIME to also load binary encoded GIFS and JPEGS from EML files 16.10.2008 - WPTools 6.00 * new installer + VCL demo * fixed problem with TWPComboBox and default attributes * updated "Tasks\Mini" demo project - fix in default actions 3.10.2008 - WPTools 6 Beta c - remove not required unit reference form WPRTEReport * update to manual 2.10.2008 - WPTools 6 Beta b - fix in Installation script 30.9.2008 - WPTools 6 Beta a 1) Application-Server-Mode WPTools 6 introduces a feature which is called "Application-Server-Mode". This is only available when you have the PREMIUM version. This mode is activated when true is assigned to the global boolean variable WPAppServerMode. When this mode is activated the editor does not use the double buffered output anymore. While this can cause some flickering the network traffic is reduced when the application runs on an application server, such as Citrix. Please note, effective with WPTools 6, software which was written for application servers (such as clinic software) may only be distributed when a TEAM or SITE license of WPTools was acquired.END 2) Integrated Label Printing When activated the integrated label printing shows multiple labels on one virtual sheet of paper. The cursor can move from label to label freely. The user can so edit the labels, add new or delete unwanted labels before the complete sheet is printed. This is a very unique and versatile feature. 3) Additions to the PDF export with wPDF V3 Create embedded data objects Create edit / memo fields Create a check box field Also the creation of PDF tags was enhanced. So now hints to paragraph styles will be also exported. 4) Additional Control over Clipboard Actions a) properties to select the format b) added security 5) Added Section API + WPRichText1.ActiveSection + WPRichText1.InputSection + TWPPagePropDlg has new method ExecuteEx. Use it to change current page size or Section WPPagePropDlg1.ExecuteEx(WPRichText1.ActiveSection); 6) Load over HTTP connections (requires Synapse) 7) Load and save MIME encoded HTML with embedded images (requires Synapse) 8) Integrated XML syntax highlighting (non destructive) 9) WPReporter: Token to Template conversion with syntax highlighting 10) Additions to paragraph API 11) Special mode to format HTML documents

其他技术讨论专区

477

社区成员

790,952

社区内容

发帖

与我相关

我的任务

其他技术论坛（原bbs）

社区管理员

加入社区

近7日
近30日
至今

加载中

查看更多榜单

社区公告

暂无公告

试试用AI创作助手写篇文章吧

+ 用AI写文章