What is Microsoft COM ISAPI?
The Internet Server Application Programming Interface (ISAPI) is an N-tier API of Internet Information Services (IIS), Microsoft’s collection of Windows-based web server services. ISAPI is a much lower-level programming system, giving much better performance, at the expense of simplicity.
What is the main function of ISAPI?
(Internet Server API) A programming interface on Internet Information Services (IIS), Microsoft’s Web server. Using ISAPI function calls, Web pages can invoke programs that are written as DLLs on the server, typically to access data in a database.
What are ISAPI extensions?
ISAPI extensions are true applications that run on IIS and have access to all of the functionality provided by IIS. Extensions and filters are the two types of applications that can be developed using ISAPI. An ISAPI extension runs when requested just like any other static HTML file or dynamic ASP file.
What is ISAPI protocol?
ISAPI is an interface to hypertext transport protocol (HTTP) servers that allows developers to extend Web servers and provide an unexpected degree of functionality.
What is ISAPI and CGI?
CGI applications must have an executable module format (. EXE). The major difference between ISAPI and CGI is that CGI is executed in separate processes for each request, but ISAPI generates a thread within a common address space in Web Servers and is executed in a multithreaded environment .
What is ISAPI module used for?
ISAPI filters are libraries loaded by the IIS web server. Every incoming request and outgoing response passes through the filters, and they’re free to perform any handling or translation they wish. They can be used for authentication, content transformation, logging, compression, and myriads of other uses.
How does ISAPI filter work?
ISAPI filters are DLL files that can be used to modify and enhance the functionality provided by IIS. ISAPI filters always run on an IIS server, filtering every request until they find one they need to process.
What is ISAPI filter?
ISAPI filters are DLL files that can be used to modify and enhance the functionality provided by IIS. ISAPI filters always run on an IIS server, filtering every request until they find one they need to process. Visual Studio comes with wizards that make ISAPI development fast and easy.
Where is ISAPI and CGI restrictions?
In Control Panel, click Programs and Features, and then click Turn Windows features on or off. Expand Internet Information Services, expand World Wide Web Services, expand Application Development Features, and then select CGI or ISAPI Extensions. Click OK.
What are ISAPI filters used for?
How do I use ISAPI?
In Control Panel, click Programs and Features, and then click Turn Windows Features on or off. In the Windows Features dialog box, expand Internet Information Services, then World Wide Web Services, then Application Development Features. Select ISAPI Filters, and then click OK.
What is ISAPI and CGI restrictions?
Overview. The element in the collection allows you to specify individual Common Gateway Interface (CGI) and Internet Server Application Programming Interface (ISAPI) applications that can run on Internet Information Services (IIS) 7.
What does the getextensionversion function do in ISAPI?
When the DLLMain finishes, the server makes a call to GetExtensionVersion function to perform two tasks: The server then calls the HttpExtensionProc function passing a copy of the ECB’s pointer to start the actual ISAPI extension. This is the function that makes writing data back to the client, possible!
What does an ISAPI extension do to a DLL?
This excessive memory usage that could bring the server completely down, has been solved under ISAPI extensions. An ISAPI extension is a regular DLL file that exposes 3 special functions that is called by the calling process (i.e., IIS) and therefore, will be loaded to memory once, no matter how many clients are going to use it at the same time.
When is terminateextension called for the ISAPI extension?
If IIS is configured to cache ISAPI extensions, TerminateExtension is not called until the IIS Web server is shut down or restarted. GetExtensionVersion is not called for every request. In contrast, HttpExtensionProc is called exactly once for every request for the ISAPI extension.
How to communicate between ISAPI extension and IIs?
As illustrated above, communicating between the extension and IIS is done via a pointer to a structure of type ECB, or Extension Control Block that is declared as follows: typedef struct _EXTENSION_CONTROL_BLOCK { DWORD cbSize; // size of this struct.