Server | refresh | No refresh about PUSH technology
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Client PULL (clients pull technology)
In general, chat rooms are constantly refreshed to display the latest information about the server, that is, the so-called client PULL (clients pull technology) client PULL must continuously establish the connection, refresh the information, disconnect, which is inefficient and slow. (If you speed up, frequent disconnect refresh page will increase server and client resource consumption)
Server push (servers pushing technology)
Push technology is to establish a connection, the server actively to the latest information flow to the client
No need to constantly build disconnected, do not need to refresh the page, in contrast, push technology more efficient and faster
But unfortunately, the ASP has been unable to implement erver push technology
Have seen the Microsoft Web site to provide ASP push technology solutions, using the dead loop to achieve server delay implementation of the servers push technology, this code as long as a client execution, CPU occupancy immediately reached 100%, the most important is the ASP thread limit, open this page, All other ASP pages must be queued for this page to finish executing.
Implementation of ASP server without flush push technology
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First I wrote a ASPpush.DLL in C + +, with the ASP code to achieve 0 load delay effect
Download Asppush.dll:http://www.1he.net/asppush/asppush.exe
Using ASP directive Enablesessionstate=false to break through ASP's thread limit
(This is the most important place, in fact, the ASP itself is multithreaded the reason why you can only get single-threaded in the ASP is the ASP for each session to produce a thread, if the ASP page in front of the enablesessionstate=false instructions, You can get a separate thread and a TCP connection to continue to push new information to the client.
Using ASP's Response.IsClientConnected attribute to judge the connection to recover resources in time
Using the above method, I made a chat room,
After testing, 100 people chat online, the system's full CPU consumption of not more than 5% (Windows 2003),
No more than a chat room with client refresh, whether in memory footprint or CPU usage
In fact, the use of client-side refresh is still a persistent resource footprint for the server, and must be frequent connection disconnect, for the chat room, the client refresh of the chat room resource occupancy is not any advantage, and the speed is very slow
Preparatory work
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Download Asppush.dll:http://www.1he.net/asppush/asppush.exe
After decompression, run first: Com.reg (this file adds a submenu of the registered Com component to the right-click menu)
Copy the ASPpush.dll to the system directory
Windows2000 $:/winnt/system32
Windows2003 $:/windows/system32
Right-click System32/asppush.dll
Click "Register DLL" in the right mouse menu
(You can, of course, register at the command line: Regsvr32 $:/windows/system32/asppush.dll)
Note: $: Replace with system disk
Sample code
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The following is a sample code that implements server push using ASPpush.DLL:
<%@ language= "VBScript" codepage = "936" Enablesessionstate=false%>
<%
Response.Buffer = True
Set Asppush = Server.CreateObject ("Asppush.page")
Do While response.isclientconnected
'================================
' Modify or customize the ASP code to be executed here
Response.Write "I faint ...<br>"
'================================
Response.Flush
The number following the Asppush.wait 100 is in milliseconds (1000 milliseconds = 1 seconds), specifying the speed of the push
Loop
Set asppush=nothing
%>
This article mainly introduces the principle of push technology in ASP, as for the specific implementation may also need your own play
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Note:
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