Difference between revisions of "OPENHOST"

Revision as of 00:46, 20 April 2020

The _OPENHOST function opens a Host which listens for new connections and returns a Host status handle.

Syntax

hostHandle = _OPENHOST("TCP/IP:8080")

Description

Creates an Illegal Function Call error if called with a string argument of the wrong syntax.
The port used in the syntax example is 8080.
Valid hostHandle values are negative numbers.
If the syntax is correct but they fail to begin/connect a hostHandle of 0 is returned.
Always check if the handle returned is 0 (failed) before continuing.
CLOSE hostHandle closes the host. A failed handle value of 0 does not need to be closed.

@@ Line 15: / Line 15: @@
 * [[CLOSE]] {{Parameter|hostHandle}} closes the host. A failed handle value of 0 does not need to be closed.
-{{PageExamples}}
-''Example:'' Chat program that attempts to connect as a Client. If not it attempts to become the Host.
-{{CodeStart}}
- {{Cl|PRINT}} "Mini Messenger"
- {{Cl|LOCATE}} , , 1 ' display the print cursor for INKEY$
- client = {{Cl|_OPENCLIENT}}("TCP/IP:7319:localhost") ' Attempt to connect to local host as a client
- {{Cl|IF...THEN|IF}} client {{Cl|THEN}}
-  {{Cl|PRINT}} "[connected to " + {{Cl|_CONNECTIONADDRESS}}(client) + "]"
-  {{Cl|_TITLE}} "Client - Mini Messenger"
-  {{Cl|INPUT}} "Enter your name: ", myname$
-  {{Cl|PRINT (TCP/IP statement)|PRINT}} #client, myname$ + " connected!"
-  {{Cl|DO...LOOP|DO}}
-   GetMessage client
-   SendMessage myname$, mymessage$, client ' display current input on screen
-   {{Cl|_DELAY}} 0.01 ' reduce CPU usage
-  {{Cl|LOOP}}
- {{Cl|ELSE}} ' "if client" alternative to open a new Host
-  {{Cl|PRINT}} "[No existing host found]"
-  host = {{Cl|_OPENHOST}}("TCP/IP:7319") ' no host found, so begin new host
-  {{Cl|IF...THEN|IF}} host {{Cl|THEN}}
-   {{Cl|_TITLE}} "Host - Mini Messenger"
-   {{Cl|PRINT}} "[Beginning new host chat session!]"
-   {{Cl|DIM}} Users(1 to 1000) ' array to hold other client info
-   numclients = 0
-   client = {{Cl|_OPENCLIENT}}("TCP/IP:7319:localhost")
-   IF client = 0 THEN PRINT "ERROR: could not attach host's personal client to host!"
-   {{Cl|INPUT}} "Enter your name:", myname$
-   {{Cl|PRINT (TCP/IP statement)|PRINT}} #client, myname$ + " connected!"
-   {{Cl|PRINT}} "[Chat session active!]"
-   {{Cl|DO...LOOP|DO}} ' host main loop
-    newclient = {{Cl|_OPENCONNECTION}}(host) ' receive any new connection
-    {{Cl|IF...THEN|IF}} newclient {{Cl|THEN}}
-     numclients = numclients + 1
-     Users(numclients) = newclient
-     {{Cl|PRINT (TCP/IP statement)|PRINT}} #Users(numclients),"Welcome!"
-    {{Cl|END IF}}
-    {{Cl|FOR...NEXT|FOR}} i = 1 {{Cl|TO}} numclients ' distribute incoming messages to all clients
-     {{Cl|IF...THEN|IF}} Users(i) {{Cl|THEN}}
-      {{Cl|INPUT (TCP/IP statement)|INPUT}} #Users(i), message$
-      {{Cl|IF...THEN|IF}} message$ <> "" {{Cl|THEN}}
-       {{Cl|FOR...NEXT|FOR}} p = 1 {{Cl|TO}} numclients
-        {{Cl|IF...THEN|IF}} Users(p) {{Cl|THEN}} {{Cl|PRINT (TCP/IP statement)|PRINT}} #Users(p), message$
-       {{Cl|NEXT}} p
-      {{Cl|END IF}}
-     {{Cl|END IF}}
-    {{Cl|NEXT}} i
-    GetMessage client ' allow host to get messages and chat also
-    SendMessage myname$, mymessage$, client
-    {{Cl|_DELAY}} 0.01 ' reduce CPU usage
-   {{Cl|LOOP}}
-  {{Cl|END IF}} ' host
-  {{Cl|PRINT}} "ERROR: Could not begin new host!"
- {{Cl|END IF}} ' if client from start
- {{Cl|SLEEP}}
- {{Cl|SYSTEM}}
-   '.................... END OF MAIN PROGRAM ................
- {{Cl|SUB}} GetMessage (client) ' get & display any new message
-  {{Cl|INPUT (TCP/IP statement)|INPUT}} #client, newmessage$
-  {{Cl|IF...THEN|IF}} newmessage$ <> "" {{Cl|THEN}}
-   {{Cl|VIEW PRINT}} 1 {{Cl|TO}} 23
-   {{Cl|LOCATE}} 23,1
-   {{Cl|PRINT}} newmessage$
-   {{Cl|VIEW PRINT}} 1 {{Cl|TO}} 24
-  {{Cl|END IF}}
- {{Cl|END SUB}}
- {{Cl|SUB}} SendMessage (myname$, mymessage$, client) ' simple input handler
-  k$ = {{Cl|INKEY$}}
-  {{Cl|IF...THEN|IF}} {{Cl|LEN}}(k$) {{Cl|THEN}}
-   {{Cl|IF...THEN|IF}} k$ = {{Cl|CHR$}}(8) {{Cl|AND (boolean)|AND}} [[LEN]](mymessage$) <> 0 {{Cl|THEN}}
-    mymessage$ = {{Cl|LEFT$}}(mymessage$, {{Cl|LEN}}(mymessage$) - 1)
-   {{Cl|ELSE}}
-    {{Cl|IF...THEN|IF}} {{Cl|LEN}}(k$) = 1 {{Cl|AND (boolean)|AND}} {{Cl|ASC}}(k$) >= 32 {{Cl|THEN}} mymessage$ = mymessage$ + k$
-   {{Cl|END IF}}
-  {{Cl|END IF}}
-  {{Cl|LOCATE}} 24, 1: {{Cl|PRINT}} {{Cl|SPACE$}}(80); ' erase previous message displayed
-  {{Cl|LOCATE}} 24, 1: {{Cl|PRINT}} myname$ + ": ";mymessage$;
-  {{Cl|IF...THEN|IF}} k$ = {{Cl|CHR$}}(13) {{Cl|THEN}} ' [Enter] sends the message
-   {{Cl|IF...THEN|IF}} mymessage$ = "" {{Cl|THEN}} {{Cl|SYSTEM}} ' [Enter] with no message ends program
-   {{Cl|PRINT (TCP/IP statement)|PRINT}} #client, myname$ + ": " + mymessage$
-   mymessage$ = ""
-  {{Cl|END IF}}
-  {{Cl|IF...THEN|IF}} k$ = {{Cl|CHR$}}(27) {{Cl|THEN}} {{Cl|SYSTEM}} ' [Esc] key ends program
- {{Cl|END SUB}}
-{{CodeEnd}}
-{{OutputStart}}
-Mini Messenger
-[No existing host found]
-[Beginning new host chat session!]
-Enter your name:_
-{{OutputEnd}}
-''Explanation:'' The SendMessage SUB program controls the program exit unless both Client and Host fail. Entering no message and hitting [Enter] or pressing the [Esc]] key closes the program. Both SUB programs allow a Client or Host to communicate with others simply. {{KW|INPUT (TCP/IP statement)|INPUT #}} is used to read messages and {{KW|PRINT (TCP/IP statement)|PRINT #}} is used to send messages. The client handle value is used as the port number. Keep in mind that this is just an example. A lot could be added, like recording IP addresses.
-<center>'''To manage the users array, see the [[_CONNECTED]] page example.'''</center>

Difference between revisions of "OPENHOST"

Revision as of 00:46, 20 April 2020

Syntax

Description

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