|
Chilkat •
HOME •
Android™ •
ASP •
Visual Basic •
VB.NET •
C# •
iOS (IPhone) •
Objective-C •
C++ •
C •
MFC •
Delphi •
FoxPro •
Java •
Perl •
PHP Extension •
PHP ActiveX •
Python •
PowerShell •
Ruby •
SQL Server •
VBScript
|
|
Understanding Asynchronous SocketsDiscusses 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.
<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body> <% set socket = Server.CreateObject("Chilkat.Socket") success = socket.UnlockComponent("Anything for 30-day trial") If (success <> 1) Then Response.Write "<pre>" & Server.HTMLEncode(socket.LastErrorText) & "</pre>" End If 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>" 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>" 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>" 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>" 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>" 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>" 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) socket.Close 20000 %> </body> </html> |
© 2000-2012 Chilkat Software, Inc. All Rights Reserved.
