(Classic ASP) (Deprecated) Asynchronous Sockets

Notice: The functionality described here is deprecated and replaced by a newer model for asynchronous method calls. The newer model was introduced in Chilkat v9.5.0.52, and is identified by methods having names ending in “Async” which return a task object.

Discusses how asynchronous sockets (in Chilkat) are used for reading, writing, connecting, and accepting connections. The same code works for both SSL/TLS and non-SSL/TLS (unencrypted) sockets.

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' Notice: The functionality described here is deprecated and replaced 
' by a newer model for asynchronous method calls. The newer model was 
' introduced in Chilkat v9.5.0.52, and is identified by methods 
' having names ending in “Async” which return a task object.

' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Socket")
set socket = Server.CreateObject("Chilkat.Socket")

useSsl = 0
maxWaitMillisec = 20000

' The remote hostname may be an IP address, a domain name,
' or "localhost".  You'll need to change this:

remoteHost = "123.123.88.88"
remotePort = 8125

' The meaning of "asynchronous" is that the socket operation, whether
' it be a read, write, connect, or accept, happens in a background
' thread and thus leaves your application free to do something
' else while the socket operation is running.
' 
' Note: If your application is simply going to initiate an asynchronous operation
' and do nothing except wait for it to complete, then it may as
' well use the synchronous socket methods -- there's no point in adding 
' complexity to your application if it's not necessary.  The meaning of "synchronous" 
' is that the method call (for reading, writing, connecting, accepting) does not 
' return until the socket operation is complete.
' 
' All asynchronous socket operations follow these basic steps:
' 1) Initiate the asynchronous socket operation.  This starts a background thread
' that does the work. The method called to initiate the asynchronous operation
' returns immediately.
' 2) Wait until the operation is completed by periodically examining the 
' "Finished" property.  Each type of socket operation has it's own "Finished" property, such as AsyncReceiveFinished.
' Once it becomes 1 or 0, you may check the "Success" property (see next step).
' 3) Once finished, you may check the "Success" property to see if the asynchronous operation 
' succeeded or failed.  Each type of socket operation has it's own "Success" property,
' such as AsynchReceiveSuccess.
' 4) If it failed, the error information is available in the "Log" property, such as "AsyncReceiveLog".
' 5) If success, then the return data is available in another property (see below).

' -------------------------------------------------------------------------
' Asynchronous Socket Methods and Properties
' -------------------------------------------------------------------------
' 
' --------------------
' Receiving Data:
' --------------------
' 
'  Methods for initiating a background receive:  
'     AsyncReceiveBytes
'     AsyncReceiveBytesN
'     AsyncReceiveString
'     AsyncReceiveToCRLF
'     AsyncReceiveUntilMatch
'  Properties:
'     AsyncReceiveFinished - Becomes 1 when completed.
'     AsyncReceiveSuccess - Set to 1 or 0 when finished.
'      AsyncReceiveLog - Error information if failed.
'     AsyncReceivedBytes - Data received if receiving binary data.
'      AsyncReceivedString -- Data received if receiving a string.
' 
' --------------------
' Sending Data:
' --------------------
' 
' Methods for initiating a background send:
'     AsyncSendBytes
'     AsyncSendString
' Properties:
'     AsyncSendFinished - Becomes 1 when completed.
'     AsyncSendSuccess - Set to 1 or 0 when finished.
'      AsyncSendLog - Error information if failed.

' --------------------
' Making a TCP Connection:
' --------------------
' 
' Method for initiating a background connect:
'     AsyncConnectStart
' Properties:
'     AsyncConnectFinished - Becomes 1 when completed.
'     AsyncConnectSuccess - Set to 1 or 0 when finished.
'      AsyncConnectLog - Error information if failed.

' --------------------
' Accepting an Incoming a TCP Connection:
' --------------------
' 
' Method for initiating a background accept:
'     AsyncAcceptStart
' Properties:
'     AsyncAcceptFinished - Becomes 1 when completed.
'     AsyncAcceptSuccess - Set to 1 or 0 when finished.
'      AsyncAcceptLog - Error information if failed.
' 
' ** After AsyncAcceptFinished becomes 1 *and* AsyncAcceptSuccess
' is 1, the connected socket may be retrieved by calling AsyncAcceptSocket.

' --------------------
' DNS Lookup
' --------------------
' 
' Method for initiating a background DNS lookup:
'     AsyncDnsStart
' Properties:
'     AsyncDnsFinished - Becomes 1 when completed.
'     AsyncDnsSuccess - Set to 1 or 0 when finished.
'      AsyncDnsLog - Error information if failed.
'      AsyncDnsResult - The IP address of the DNS lookup if successful.

' The following code demonstrates connecting, sending, and receiving asynchronously.
' NOTE: This example simply waits for each background operation
' to complete.  In general, the whole point of doing something
' asynchronously is so your application is free to do other things,
' such as manage the user-interface.  

' Connect to the remote host asynchronously in a background thread.
success = socket.AsyncConnectStart(remoteHost,remotePort,useSsl,maxWaitMillisec)
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( socket.LastErrorText) & "</pre>"
    Response.End
End If

' Wait for the socket to become connected...
Do While (socket.AsyncConnectFinished <> 1)
    ' Sleep 1 second.
    socket.SleepMs 100
Loop

' Did the connect fail?
If (socket.AsyncConnectSuccess <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( socket.AsyncConnectLog) & "</pre>"
    Response.End
End If

' Set maximum timeouts for reading an writing (in millisec)
socket.MaxReadIdleMs = 20000
socket.MaxSendIdleMs = 20000

' Send a "Hello Server! -EOM-" message:
success = socket.AsyncSendString("Hello Server! -EOM-")
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( socket.LastErrorText) & "</pre>"
    Response.End
End If

' Wait for the send to finish
Do While (socket.AsyncSendFinished <> 1)
    ' Sleep 1 second.
    socket.SleepMs 100
Loop

' Did the send fail?
If (socket.AsyncSendSuccess <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( socket.AsyncSendLog) & "</pre>"
    Response.End
End If

' The server (in this example) is going to send a "Hello Client! -EOM-" 
' message.  Begin reading asynchronously in a background thread:
success = socket.AsyncReceiveUntilMatch("-EOM-")
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( socket.LastErrorText) & "</pre>"
    Response.End
End If

' Wait for the background read to finish
Do While (socket.AsyncReceiveFinished <> 1)
    ' Sleep 1 second.
    socket.SleepMs 100
Loop

' Did the receive fail?
If (socket.AsyncReceiveSuccess <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( socket.AsyncReceiveLog) & "</pre>"
    Response.End
End If

' Display the received message:
Response.Write "<pre>" & Server.HTMLEncode( socket.AsyncReceivedString) & "</pre>"

' Close the connection with the server
' Wait a max of 20 seconds (20000 millsec)
success = socket.Close(20000)

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