4D Doc Center : TCP

4D v13.2

TCP_ReceiveBLOB


TCP_ReceiveBLOB ( tcp_ID ; blobToReceive ) -> Function result

Parameter	Type	Description
tcp_ID	Longint	Reference to an open TCP session
blobToReceive	BLOB	BLOB to receive data
Function result	Integer	Error Code

Description

Given a long integer reference to an established TCP session, the TCP_ReceiveBLOB command receives packets of data into blobToReceive.

This command performs the same action as TCP_Receive, except that it will receive data in a BLOB instead of a text, which allows bypassing the 32K text limitation. You can then receive binary objects.

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

blobToReceive is the BLOB which receives data. When receiving data via TCP packets, you cannot count on all of your data being received by a single TCP_ReceiveBLOB call. The TCP_ReceiveBLOB command is usually called within a Repeat...Until loop which continually checks on the status of the connection or is scanning for a known value.

Example

This example shows the typical structure of a method using TCP_ReceiveBLOB:

 C_BLOB($Blob_Received;$Blob_All)

 C_LONGINT($srcpos;$dstpos)

 Repeat

    $Err:=TCP_ReceiveBLOB($TCP_ID;$Blob_Received )

    $Err:=TCP_State($TCP_ID;$State)

    $srcpos:=0

    $dstpos:=BLOB size($Blob_All)

  `Concatenating received Blobs

    COPY BLOB($Blob_Received;$Blob_All;$srcpos;$dstpos;BLOB size($Blob_Received))

 Until(($State=0)|($Err#0))