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Purpose |
Enable an application to communicate with a TCP/IP server or client using the TCP protocol over Winsock. |
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Syntax |
As a client: TCP OPEN {PORT p& | srvc$} AT host$ AS [#] fNum& [TIMEOUT timeoutval&] As a server: TCP OPEN SERVER [ADDR ip&] {PORT p& | srvc$} AS [#] fNum& [TIMEOUT timeoutval&] |
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Remarks |
Open a TCP/IP port or service for communication, either as a client or as a server. |
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SERVER |
If the keyword server is included, the TCP port is opened as a TCP/IP server; otherwise, it is opened as a TCP/IP client. |
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ADDR ip& |
As a server, if you specify the optional ADDR ip&, the TCP server monitors connections at the specified ip& address. Otherwise, the primary IP address for the computer is used by default. |
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PORT p& |
As a client, PORT identifies the server port that the client attempts to connect to. As a server, PORT identifies the port the server will monitor for connection requests. You may specify either a port number or a service name, but not both. |
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srvc$ |
If the port number is not specified, a service name must be specified instead. A service name takes the form of "http", "smtp", or "ftp", etc. You may specify either a port number or a service name, but not both. |
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AT host$ |
As a client, host$ identifies the host to connect with. host$ can be a domain such as "powerbasic.com", or a dotted IP address in string form, such as "127.0.0.1". |
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fNum& |
A file number such as #1, or a variable with a value obtained using the FREEFILE function. |
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TIMEOUT |
The optional TIMEOUT value allows you to specify how long a TCP SEND, RECV, PRINT, or LINE operation should wait for completion, in milliseconds (mSec). If the specified number of milliseconds elapses without a response, the TCP operation will fail, and the ERR system variable will be set to indicate a run-time Error 24 ("Device timeout"). The default timeout is 60000 milliseconds (60 seconds). |
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See also |
TCP and UDP communications, FREEFILE, TCP ACCEPT, TCP CLOSE, TCP LINE INPUT, TCP NOTIFY, TCP PRINT, TCP RECV, TCP SEND, UDP OPEN |
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Example |
' Client TCP/IP example - retrieve a web page #COMPILE EXE
FUNCTION PBMAIN() AS LONG LOCAL Buffer$, Site$ LOCAL Entire_page$, Htmlfile$, Link$ LOCAL Pos&, Length&
Site$ = "www.powerbasic.com" File$ = "http://www.powerbasic.com/support/forums/Forum2/HTML/000031.html"
' Connecting... TCP OPEN "http" AT Site$ AS #1 TIMEOUT 60000
' Could we connect to site? IF ERR THEN BEEP EXIT FUNCTION END IF
' Send the GET request... TCP PRINT #1, "GET " & File$ & " HTTP/1.0" TCP PRINT #1, "Referer: http://www.powerbasic.com/" TCP PRINT #1, "User-Agent: TCP OPEN Example (www.powerbasic.com) TCP PRINT #1, ""
' Retrieve the page... DO TCP RECV #1, 4096, Buffer$ Entire_page = Entire_page + Buffer$ LOOP WHILE ISTRUE LEN(Buffer$) AND ISFALSE ERR
' Close the TCP/IP port... TCP CLOSE #1 END FUNCTION |