4D Doc Center : TCP

4D v13.2

TCP_State


TCP_State ( tcp_ID ; statusCode ) -> Function result

Parameter	Type	Description
tcp_ID	Longint	Reference to an open TCP
statusCode	Integer	TCP status code
Function result	Integer	Error Code

Description

The TCP_State command returns an integer value corresponding to the state of a particular TCP connection.

tcp_ID is a long integer reference to an open TCP session as established with either the TCP_Open or TCP_Listen command.

statusCode is an integer variable returned which corresponds to one of the status codes below.

0	Connection Closed
2	Listening for an incoming connection
8	Established

This example assumes that a valid TCP connection has already been established and is identified by the Longint value assigned to the $tcp_id variable. In this example, a command is sent to a web server requesting a page of information and then a loop is entered to receive the results. Since web servers automatically close their connnections once they have performed their action, this example keeps receiving until the connection is dropped or an error occurs.

 C_LONGINT($tcp_id)

 C_INTEGER(vState;$err)

 C_TEXT($command;$buffer;$response)

 If(TCP_Send($tcp_id;$command)=0)

    vState:=0

    Repeat

       $err:=TCP_Receive($tcp_id;$buffer)

       $err:=TCP_State($tcp_id;vState)

       $response:=$response+$buffer

    Until((vState=0)|($err#0))

 End if

4D v13.2

TCP_State

TCP_State

Description

Example