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ISAPI SERVEREXTENSIONS

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A program implemented as a dll and loaded by IIS.

Run in response to a GET or POST request from a client

program ( browser )

Sends back HTML code.

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A part of HTTP and a way for browser programs to interact

with scripts.

Using CGI parameters , browser sends small amounts of data

to server.

Server can access databases , generate images and control

peripheral devices.

Server sends back HTML code to browser.

CGI and ISAPI

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Consider the following HTML code ;

Chennai map

When user clicks on Chennai map , browser sends

the following CGI GET request to the server ;

GET scripts/maps.dll ? City = chennai HTTP/1.0

IIS then loads maps.dll from the scripts directory and calls a default

function ( Default ) , and passes a parameter chennai.The dll generates a jpg file containing the latest

satellite image of Chennai and sends it to the client.

A SIMPLE ISAPI SERVER EXTENSION GET

REQUEST

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If maps.dll has more than one function ;

Chennai map

In this case , GetMap() called with two parameters

(i) City

(ii) Res

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HTML forms GET vs POST

City map

Welcome to Satellite map service

Select your city :

Delhi

Chennai

Mumbai

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OUTPUT

The CGI request looks something like this ;

GET scripts/maps.dll ? GetMap ? City = chennai HTTP / 1.0

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Using POST method

HTML code ;

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WRITING AN ISAPI SERVER EXTENSION DLL

VC++ File New ISAPI ExtensionWizard Give a name (isapi) Ok

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A class is derived from the MFC CHttpServer class and a Default member

function is included.

Insert the below lines into isapi.cpp ;

BEGIN_PARSE_MAPON_PARSE_COMMAND ( GetMap , CWeatherExtension , ITS_PSTR)

ON_PARSE_COMMAND_PARAMS ( city )

END_PARSE_MAP

void CIsapiExtension::GetMap(CHttpServerContext* pCtxt,LPCTSTR pstrCity)

{StartContent(pCtxt);

WriteTitle(pCtxt);

*pCtxt

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View ClassWizard Message maps Add function GetTitle()

LPCTSTR CIsapiExtension :: GetTitle () const

{

return Your custom map ;

}

In isapi.h ;

Void GetMap ( CHttpServerContext * pCtxt , LPCTSTR pstrCity ) ;

The CHttpServerContext class has an overloaded

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THE MFC ISAPI SERVER EXTENSION CLASSES

CHttpServer

CHttpServerContext

CHtmlStream

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THANK YOU