OPENCLIENT

The _OPENCLIENT function connects to a Host on the Internet as a Client and returns the Client status handle.

Syntax

clientHandle& = _OPENCLIENT("TCP/IP:8080:12:30:1:10")

Description

• An Illegal Function Call error will be triggered if the function is called with a string argument of the wrong syntax.
• Connects to a host somewhere on the internet as a client.
• Valid clientHandle& values are negative. 0 means that the connection failed. Always check that the handle returned is not 0.
• CLOSE client_handle closes the client. A failed handle of value 0 does not need to be closed.

Examples

Example 1: Attempting to connect to a local host(your host) as a client. A zero return indicates failure.

client = _OPENCLIENT("TCP/IP:7319:localhost") IF client THEN PRINT "[Connected to " + _CONNECTIONADDRESS(client) + "]" ELSE PRINT "[Connection Failed!]" END IF

NOTE: Try a valid TCP/IP port setting to test this routine!

Example 2: Using a "raw" Download function to download the QB64 bee image and displays it.

'replace the fake image address below with a real image address you want to download IF Download("www.qb64.org/qb64.png", "qb64logo.png", 10) THEN ' timelimit = 10 seconds SCREEN _LOADIMAGE("qb64logo.png",32) ELSE: PRINT "Couldn't download image." END IF SLEEP SYSTEM ' ---------- program end ----------- FUNCTION Download (url$, file$, timelimit) ' returns -1 if successful, 0 if not url2$ = url$ x = INSTR(url2$, "/") IF x THEN url2$ = LEFT$(url$, x - 1) client = _OPENCLIENT("TCP/IP:80:" + url2$) IF client = 0 THEN EXIT FUNCTION e$ = CHR$(13) + CHR$(10) ' end of line characters url3$ = RIGHT$(url$, LEN(url$) - x + 1) x$ = "GET " + url3$ + " HTTP/1.1" + e$ x$ = x$ + "Host: " + url2$ + e$ + e$ PUT #client, , x$ t! = TIMER ' start time DO _DELAY 0.05 ' 50ms delay (20 checks per second) GET #client, , a2$ a$ = a$ + a2$ i = INSTR(a$, "Content-Length:") IF i THEN i2 = INSTR(i, a$, e$) IF i2 THEN l = VAL(MID$(a$, i + 15, i2 - i -14)) i3 = INSTR(i2, a$, e$ + e$) IF i3 THEN i3 = i3 + 4 'move i3 to start of data IF (LEN(a$) - i3 + 1) = l THEN CLOSE client ' CLOSE CLIENT d$ = MID$(a$, i3, l) fh = FREEFILE OPEN file$ FOR OUTPUT AS #fh: CLOSE #fh ' erase existing file? OPEN file$ FOR BINARY AS #fh PUT #fh, , d$ CLOSE #fh Download = -1 'indicates download was successfull EXIT FUNCTION END IF ' availabledata = l END IF ' i3 END IF ' i2 END IF ' i LOOP UNTIL TIMER > t! + timelimit ' (in seconds) CLOSE client END FUNCTION

See also

• _OPENHOST, _OPENCONNECTION
• _CONNECTED, _CONNECTIONADDRESS$
• Email Demo, Inter-Program Data Sharing Demo
• Downloading Files

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