SocketConnect (Function)

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Optimizing the connections for an IP address
Timeout

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SocketConnect (Function)

In french: SocketConnecte

Connects a client computer to a given socket.

Remarks:

UDP sockets: The UDP protocol being a "connectionless" protocol, SocketConnect cannot be used with the UDP protocol. To send or receive data with the UDP protocol, you must create a UDP socket (SocketCreateUDP) then send/receive data with the "special UDP" syntaxes of SocketWrite and SocketRead.
SSL sockets: To send or receive data with the SSL protocol, you must create an SSL socket (SocketCreateSSL) and connect to this socket with SocketConnectSSL.
Communication with robots or with non-WINDEV applications: To simplify the exchanges of data by socket, a transmission mode is initialized by default. For a communication with an external module (non-WINDEV application, robot, ...), this transmission mode can prevent the communications from operating properly. SocketChangeTransmissionMode is used to change this transmission mode (the SocketNoEndTag constant allows you not to modify the frames read and written).
Versions 22 and later
Websockets: The WebSockets are used to communicate from a Web application (Intranet or Internet site run in a browser) to a Web server by using sockets. SocketConnect is used to connect to the WebSockets server. See Managing WebSockets for more details.
New in version 22
Websockets: The WebSockets are used to communicate from a Web application (Intranet or Internet site run in a browser) to a Web server by using sockets. SocketConnect is used to connect to the WebSockets server. See Managing WebSockets for more details.
Websockets: The WebSockets are used to communicate from a Web application (Intranet or Internet site run in a browser) to a Web server by using sockets. SocketConnect is used to connect to the WebSockets server. See Managing WebSockets for more details.

Reminder: A socket is a communication resource used by the applications to communicate between computers regardless of the network type.

Versions 22 and later

This function is now available in browser code.

New in version 22

This function is now available in browser code.

Example

IF SocketConnect("Server", 8000) = False THEN
Error("Connection error" + ErrorInfo(errMessage))
END

Versions 22 and later

SocketConnect("client", "ws://<ServerIPAddress>:5001", ReturnProc)

PROCEDURE ReturnProc(nEvent, sMessage)gsRes is string = ""

SWITCH nEvent
CASE SocketOpening:
SocketWrite("client", "Send message from the browser.")
RETURN
CASE SocketMessage: gsRes += [CR] + "Receiving message: " + sMessage
CASE SocketClosing: gsRes += [CR] + "Closing the socket"
CASE SocketError:
gsRes += [CR] + "Error of socket: " + sMessage
RETURN
OTHER CASE
END
Info(gsRes)

New in version 22

SocketConnect("client", "ws://<ServerIPAddress>:5001", ReturnProc)

Syntax

Connecting to a socket Hide the details

<Result> = SocketConnect(<Socket name> , <Port number> [, <Address> [, <Maximum timeout>]])

<Result>: Boolean

True if the function was successful,
False otherwise. In the event of an error, it is possible to find out the details of the error using the ErrorInfo function.

<Socket name>: Character string (with quotes)

Name that will be given to the connection opened on the server socket. This name will be used by all socket functions.

<Port number>: Integer

Port number of socket. If you are using a socket associated with a preset protocol, use the port number associated with the protocol.
If the socket was created by a WINDEV application, this number must be included between 5 000 and 65 000. In this case, the number must be identical to the port number specified in SocketCreate.

<Address>: Optional character string (with quotes)

Address of server. If this parameter is not specified, the server is sought on the current computer. This address can be given in the following format:
IP address in XXX.XXX.XXX.XXX format (125.5.110.100 for example).
URL containing the server name (www.windev.com for example). This syntax is recommended.
The address can also correspond to the IP address returned by NetIPAddress.

<Maximum timeout>: Optional integer or optional Duration

Maximum timeout (in milliseconds) for establishing the connection. This delay is only used if the server refuses the connection (function SocketDeny). In this case, the connection will not be locking. This parameter can correspond to:
an integer corresponding to the number of milliseconds,
a Duration variable,
Versions 23 and later
the direct indication of duration (1 s or 10 ms for example).
New in version 23
the direct indication of duration (1 s or 10 ms for example).
the direct indication of duration (1 s or 10 ms for example).
This time-out is set to 5000 milliseconds by default (5 seconds). See remarks for more details.
This parameter is ignored.

Versions 22 and later

Connecting to a WebSocket Hide the details

SocketConnect(<Socket name> , <Address> , <Name of Browser Procedure> [, <Protocol(s)>])

<Socket name>: Character string (with quotes)

Name that will be given when connecting to the server. This name will be used by all socket functions. Caution: The socket name is case sensitive.

<Address>: Character string (with quotes)

Address of the WebSockets server that will be used for the connection. This address has the following format: ws[s]://server[:port][/directoryX/.../]. In this case:
the ws prefix indicates that the server is a WebSockets server. wss is used for a secure WebSockets server.
server corresponds to the server address in the following format: server name, domain name or IP address of server.
port corresponds to the number of the communication port used to dialog with the server. This number must be identical to the port number specified in SocketCreate if the WebSockets server was created in WLanguage with WINDEV or WEBDEV.
directoryX corresponds to the possible virtual directories of server.

<Name of Browser Procedure>: Character string (with or without quotes)

Name of WLanguage procedure written in browser code ("callback" procedure). Name of procedure called when the connection to the server is established. This procedure is used to send a message to the server with SocketWrite.
This procedure has the following format:

PROCEDURE <Procedure Name>(<Event>, <Message>)

where:
<Event> corresponds to one of the following constants:
SocketOpening The socket is connected to the server. You have the ability to send messages.
SocketClosing The socket is closed. The <Message> parameter contains a code that indicates the reason for closing.
SocketError An error occurred during the communication with the server. The <Message> parameter is always empty.
SocketMessage The socket received a message. The <Message> parameter contains data relative to the message.
<Message> corresponds to the message received as server response according to the <Event>.
Remark: There is no need to pass parameters to this procedure. Indeed, these parameters are automatically filled.

<Protocol(s)>: Character string (with quotes) or array of character strings (optional)

Protocol(s) corresponding to the format of WebSocket response. For example: "JSON", "XML". If this parameter is not specified or if it corresponds to an empty string, no protocol is used.

New in version 22

Connecting to a WebSocket Hide the details

SocketConnect(<Socket name> , <Address> , <Name of Browser Procedure> [, <Protocol(s)>])

<Socket name>: Character string (with quotes)

Name that will be given when connecting to the server. This name will be used by all socket functions. Caution: The socket name is case sensitive.

<Address>: Character string (with quotes)

Address of the WebSockets server that will be used for the connection. This address has the following format: ws[s]://server[:port][/directoryX/.../]. In this case:
the ws prefix indicates that the server is a WebSockets server. wss is used for a secure WebSockets server.
server corresponds to the server address in the following format: server name, domain name or IP address of server.
port corresponds to the number of the communication port used to dialog with the server. This number must be identical to the port number specified in SocketCreate if the WebSockets server was created in WLanguage with WINDEV or WEBDEV.
directoryX corresponds to the possible virtual directories of server.

<Name of Browser Procedure>: Character string (with or without quotes)

Name of WLanguage procedure written in browser code ("callback" procedure). Name of procedure called when the connection to the server is established. This procedure is used to send a message to the server with SocketWrite.
This procedure has the following format:

PROCEDURE <Procedure Name>(<Event>, <Message>)

where:
<Event> corresponds to one of the following constants:
SocketOpening The socket is connected to the server. You have the ability to send messages.
SocketClosing The socket is closed. The <Message> parameter contains a code that indicates the reason for closing.
SocketError An error occurred during the communication with the server. The <Message> parameter is always empty.
SocketMessage The socket received a message. The <Message> parameter contains data relative to the message.
<Message> corresponds to the message received as server response according to the <Event>.
Remark: There is no need to pass parameters to this procedure. Indeed, these parameters are automatically filled.

<Protocol(s)>: Character string (with quotes) or array of character strings (optional)

Protocol(s) corresponding to the format of WebSocket response. For example: "JSON", "XML". If this parameter is not specified or if it corresponds to an empty string, no protocol is used.

Connecting to a WebSocket Hide the details

SocketConnect(<Socket name> , <Address> , <Name of Browser Procedure> [, <Protocol(s)>])

<Socket name>: Character string (with quotes)

Name that will be given when connecting to the server. This name will be used by all socket functions. Caution: The socket name is case sensitive.

<Address>: Character string (with quotes)

Address of the WebSockets server that will be used for the connection. This address has the following format: ws[s]://server[:port][/directoryX/.../]. In this case:
the ws prefix indicates that the server is a WebSockets server. wss is used for a secure WebSockets server.
server corresponds to the server address in the following format: server name, domain name or IP address of server.
port corresponds to the number of the communication port used to dialog with the server. This number must be identical to the port number specified in SocketCreate if the WebSockets server was created in WLanguage with WINDEV or WEBDEV.
directoryX corresponds to the possible virtual directories of server.

<Name of Browser Procedure>: Character string (with or without quotes)

Name of WLanguage procedure written in browser code ("callback" procedure). Name of procedure called when the connection to the server is established. This procedure is used to send a message to the server with SocketWrite.
This procedure has the following format:

PROCEDURE <Procedure Name>(<Event>, <Message>)

where:
<Event> corresponds to one of the following constants:
SocketOpening The socket is connected to the server. You have the ability to send messages.
SocketClosing The socket is closed. The <Message> parameter contains a code that indicates the reason for closing.
SocketError An error occurred during the communication with the server. The <Message> parameter is always empty.
SocketMessage The socket received a message. The <Message> parameter contains data relative to the message.
<Message> corresponds to the message received as server response according to the <Event>.
Remark: There is no need to pass parameters to this procedure. Indeed, these parameters are automatically filled.

<Protocol(s)>: Character string (with quotes) or array of character strings (optional)

Protocol(s) corresponding to the format of WebSocket response. For example: "JSON", "XML". If this parameter is not specified or if it corresponds to an empty string, no protocol is used.

Remarks

Optimizing the connections for an IP address

When an IP address is passed to SocketConnect, the connection can be optimized by using the following code:

Socket.Option = SocketOptimizeIPConnection

CThis option is not enabled by Default because the connection may fail in some configurations.. However, it may be useful in some applications for which the performances are critical.

Remark: To restore the default operating mode, all you have to do is use the SocketOptionDefault constant:

Socket.Option = SocketOptionDefault

Timeout

The timeout specified by <Maximum timeout> groups the timeout of two steps:

the timeout for address resolution: this time-out cannot be configured and it can be optimized (see below).
the maximum timeout for the connection to be accepted by the server. Several cases may occur:
- the server refuses the connection.
- the server accepts the connection within the timeout.
- the server is not available.
- the specified address is invalid.

In order to optimize the resolution time of the Address (the search time of the Address), it is recommended:

use a DNS on the network. Therefore, this address will be sought toward this server and not for each computer (1 search instead of x searches where x represents the number of computers). Each computer must be registered toward this server.
for an IP address, use the Socket.Option variable as follows:

Socket.Option = SocketOptimizeIPConnection

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