ISBN: For information on all col/Internet Protocal (TCP/IP) —and Sockets was designed to support them all. Fewer protocol families were. docs/TCP IP Sockets in C, Second Edition Practical Guide for wm-greece.info Find file Copy path. Fetching contributors Cannot retrieve contributors at this. Originally published as The Pocket Guide to TCP/IP Sockets: C Version ( ). 06 5 ISBN ISBN
|Language:||English, Spanish, German|
|Distribution:||Free* [*Sign up for free]|
download TCP/IP Sockets in C - 2nd Edition. Print Book & E-Book. ISBN , TCP/IP Sockets in C, 2nd Edition. 4 reviews. by Kenneth L. Calvert, Michael J. Donahoo. Publisher: Morgan Kaufmann. Release Date: March ISBN. ISBN TCP/IP Sockets in C: Practical Guide for Programmers, 2nd Edition is a quick and affordable way to gain the knowledge.
TCP does not preserve read and write message boundaries. That is, even though we sent the echo string with a single write , the echo server may receive it in multiple chunks. Even if the echo string is handled in one chunk by the echo server, the reply may still be broken into pieces by TCP. One of the most common errors for beginners is the assumption that data sent by a single write will always be received in a single read.
We can communicate with an echo server named server. Specifying the local address may be useful on a host with multiple interfaces.
String arguments that specify destinations can be in the same formats that are accepted by the InetAddress creation methods. The last constructor creates an unconnected socket, which must be explicitly connected via the connect method, see below before it can be used for communication.
Stream methods. Any subsequent attempt to read from the socket will cause an exception to be thrown.
See Section 4. Caveat: By default, Socket is implemented on top of a TCP connection; however, in Java, you can actually change the underlying implementation of Socket. The Socket class actually has a large number of other associated attributes referred to as socket options. Because they are not necessary for writing basic applications, we postpone introduction of them until Section 4.
The constructor that takes a string hostname attempts to resolve the name to an IP address; the 2. The isUnresolved method returns true if the instance was created this way, or if the resolution attempt in the constructor failed. The get If the InetSocketAddress is unresolved, only the String with which it was created precedes the colon.
The typical TCP server goes through two steps: 1. Construct a ServerSocket instance, specifying the local port. Repeatedly: a. Call the accept method of ServerSocket to get the next incoming client connection. Upon establishment of a new client connection, an instance of Socket for the new connection is created and returned by accept.
The server is very simple. It runs forever, repeatedly accepting a connection, receiving and echoing bytes until the connection is closed by the client, and then closing the client socket. We are done with this client! Application setup and parameter parsing: lines 0—12 2.
If a connection arrives between the time the server socket is constructed and the call to accept , the new connection is queued, and in that case accept returns immediately. See Section 6. The accept method of ServerSocket returns an instance of Socket 2. The name part is empty because the instance was created from the address information only. The read method of InputStream fetches up to the maximum number of bytes the array can hold in this case, BUFSIZE bytes into the byte array receiveBuf and returns the number of bytes read.
In fact, it can return after having read only a single byte. In this case, 0 indicates to take bytes starting from the front of data. Valid port numbers are in the range 0—65, Optionally, the size of the connection queue and the local address can also be set. Note that the maximum queue size may not be a hard limit, and cannot be used to control client population.
This may be useful for hosts with multiple interfaces where the server wants to accept connections on only one of its interfaces. The fourth constructor creates a ServerSocket that is not associated with any local port; it must be bound to a port see bind below before it can be used. ServerSocket: Operation void bind int port void bind int port, int queuelimit Socket accept void close The bind methods associate this socket with a local port.
A ServerSocket can only be associated with one port.
If no established connection is waiting, accept blocks until one is established or a timeout occurs. The close method closes the socket. After invoking this method, incoming client connection requests for this socket are rejected. It does, however, have other attributes called options, which can be controlled via various methods, as described in Section 4. The NIO facilities, added in Java 1. A stream is simply an ordered sequence of bytes.
Java input streams support reading bytes, and output streams support writing bytes.
When we write to the output stream of a Socket, the bytes can eventually be read from the input stream of the Socket at the other end of the connection. OutputStream is the abstract superclass of all output streams in Java. OutputStream: Operation abstract void write int data void write byte[ ] data void write byte[ ] data, int offset, int length void flush void close The write methods transfer to the output stream a single byte, an entire array of bytes, and the bytes in an array beginning at offset and continuing for length bytes, respectively.
The single-byte method writes the low-order eight bits of the integer argument. These operations, if called on a stream associated with a TCP socket, may block if a lot of data has been sent, but the other end of the connection has not called read on the associated input stream recently. This can have undesirable consequences if some care is not used see Section 6. The close method terminates the stream, after which further calls to write will throw an exception.
InputStream is the abstract superclass of all input streams. Using an InputStream, we can read bytes from and close the input stream.
The second form transfers up to data. The third form does the same, but places data in the array beginning at offset, and transfers only up to length bytes. If no data is available, but the end-of-stream has not been detected, all the read methods block until at least one byte can be read.
The available method returns the number of bytes available for reading at the time it was called. In fact, UDP performs only two functions: 1 it adds another layer of addressing ports to that of IP, and 2 it detects some forms of data corruption that may occur in transit and discards any corrupted messages.
For example, UDP sockets do not have to be connected before being used. Similarly, each message—called a datagram—carries its own address information and is independent of all others. This makes receiving an application message simpler, in some ways, than it is with TCP sockets. This is discussed further in Section 2. A program using UDP sockets must therefore be prepared to deal with loss and reordering.
Both clients and servers use DatagramSockets to send and receive DatagramPackets. To send, a Java program constructs a DatagramPacket instance containing the data to be sent and passes it as an argument to the send method of a DatagramSocket.
In addition to the data, each instance of DatagramPacket also contains address and port information, the semantics of which depend on whether the datagram is being sent or received.
When a DatagramPacket is sent, the address and port identify the destination; for a received DatagramPacket, they identify the source of the received message. See the following reference and Section 2. DatagramPacket: Creation DatagramPacket byte[ ] DatagramPacket byte[ ] DatagramPacket byte[ ] DatagramPacket byte[ ] DatagramPacket byte[ ] DatagramPacket byte[ ] data, data, data, data, data, data, int int int int int int length offset, int length length, InetAddress remoteAddr, int remotePort offset, int length, InetAddress remoteAddr, int remotePort length, SocketAddress sockAddr offset, int length, SocketAddress sockAddr These constructors create a datagram whose data portion is contained in the given byte array.
The last four forms are typically used to construct DatagramPackets for sending. The internal datagram length can be set explicitly either by the constructor or by the setLength method. There is no setOffset method; however, it can be set with setData. The getData method returns the byte array associated with the datagram. The returned object is a reference to the byte array that was most recently associated with this DatagramPacket, either by the constructor or by setData.
The setData methods make the given byte array the data portion of the datagram. The typical UDP client goes through three steps: 1. Construct an instance of DatagramSocket, optionally specifying the local address and port.
Communicate by sending and receiving instances of DatagramPacket using the send and receive methods of DatagramSocket. A UDP echo server simply sends each datagram that it receives back to the client. Many systems include a UDP echo server for debugging and testing purposes. One consequence of using UDP is that datagrams can be lost. In the case of our echo protocol, either the echo request from the client or the echo reply from the server may be lost in the network. Recall that our TCP echo client sends an echo string and then blocks on read waiting for a reply.
If we try the same strategy with our UDP echo client and the echo request datagram is lost, our client will block forever on receive. To avoid this problem, our client 30 Chapter 2: Basic Sockets uses the setSoTimeout method of DatagramSocket to specify a maximum amount of time to block on receive , so it can try again by resending the echo request datagram.
Our echo client performs the following steps: 1. Send the echo string to the server. Terminate the client.
DatagramSocket; java. If you order multiple items and they are not all in stock, we will advise you of their anticipated arrival times. For items not readily available, we'll provide ongoing estimated ship and delivery time frames.
Once your order has been dispatched from our Sydney warehouse you will receive an Order Shipped status email. This will contain your tracking information All our estimates are based on business days and assume that shipping and delivery don't occur on holidays and weekends. Delivery with Standard Australia Post usually happens within business days from time of dispatch. Please be aware that the delivery time frame may vary according to the area of delivery and due to various reasons, the delivery may take longer than the original estimated timeframe.
If you have not received your delivery following the estimated timeframe, we advise you to contact your local post office first, as the parcel may be there awaiting your collection. If you have not received any information after contact with Australia Post, please contact us to confirm that the details for delivery logged with us are correct.
We will then contact you with the appropriate action. The consignment number is emailed to you along with the invoice at the time of shipment.