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- Overview
- The simplified server
- Step 1: Socket creation
- Step 2: Data exchange
- Step 3: Closing the socket
- Transmission mode of information
Socket: Creating a simplified socket server
WINDEV gives you the ability to create a simplified socket server. This server communicates with a single client computer at a time. This type of application is very useful when two remote applications must communicate. Step 1: Socket creation To create the socket, the server uses SocketCreate. A socket is bound to a specific port. To easily use sockets programmatically on the server, specify the socket name. The client machine will connect to the socket to exchange data. The connection will be actually established at the first data exchange between the two machines (i.e. when the server reads information for the first time). The connection is established the first time SocketRead reads information on the server successfully. Step 2: Data exchange When two machines use the same socket, a communication stream is established between them. These two machines can read from and write character strings to the socket. Note: To avoid blocking applications, message reception is often managed by a specific thread (for more details on threads, see Thread management). Caution: To perform a read, a write must have been performed.. For example: - The client computer writes to the socket: it sends a request to the server.
- The server reads data from the socket in a thread. When a message is received, it is processed by the server.
- If a response to the message is required, the server identifies the client computer (SocketClientInfo) and sends a response.
Step 3: Closing the socket To end the communication, the server can close the socket with SocketClose. Note: the socket can also be closed by the client workstation. Transmission mode of information The transmission mode of the message defines the mode used to specify the length of the message. Several methods can be used to define the length of message during the communication between sockets. Method 1: WINDEV mode: By default, the number of characters of the message is indicated at the beginning of the message.. This transmission mode is recommended when the sockets are used to communicate between two WINDEV applications. The message looks like this: "11\r\nHelloWorld". Method 2: standard mode: end of message is signaled by a specific, pre-determined character. This transmission mode is recommended when the sockets are used to communicate between a WINDEV application and another application. In this case, a specific character must be included in the message to indicate that the message is over. The message is in the form: "Hello World<EOF>". Method 3: standard mode with buffer: Corresponds to the standard mode optimized for the protocols most commonly used on the Internet.
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