What is the use of these filters in atg

Question

Hi Guys,
In my web.xml file i have code like this
<filter>
        <filter-name>PageFilter</filter-name>
        <filter-class>atg.filter.dspjsp.PageFilter</filter-class>
    </filter>
    <filter>
        <filter-name>ForwardFilter</filter-name>
        <filter-class>atg.servlet.ForwardFilter</filter-class>
    </filter>
    <filter>
        <filter-name>ErrorFilter</filter-name>
        <filter-class>atg.servlet.ErrorFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>ErrorFilter</filter-name>
        <url-pattern>/*</url-pattern>
        <dispatcher>ERROR</dispatcher>
    </filter-mapping>
    <filter-mapping>
        <filter-name>ForwardFilter</filter-name>
        <url-pattern>/*</url-pattern>
        <dispatcher>FORWARD</dispatcher>
        <dispatcher>ERROR</dispatcher>       
    </filter-mapping>
    <filter-mapping>
        <filter-name>PageFilter</filter-name>
        <url-pattern>/*</url-pattern>
        <dispatcher>REQUEST</dispatcher>
        <dispatcher>ERROR</dispatcher>       
        <dispatcher>FORWARD</dispatcher>
    </filter-mapping>
what is the use of these filters what will happend if i remove these filters in web.xml file
please give me clear picture on these 3 filters and how these filters are helpful in our application.

Answer 1

As the name filter suggest, All the request will go though these filters if certian condition is satisfied
In ATG web.xml contains following filter:
<filter>
    <filter-name>PageFilter</filter-name>
    <filter-class>atg.filter.dspjsp.PageFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>PageFilter</filter-name>
    <url-pattern>*.jsp</url-pattern>
</filter-mapping>
When there is .jsp in url pattern all the request will go through Page Filter.
Filter is java concept.For More details about Filter, Refer http://docs.oracle.com/cd/E19502-01/819-3669/6n5sg7b0b/index.html
In order to process Jsp request, ATG use Page filter. It converts normal HttpRequest/HttpResponse to DynamoHttpRequest/DynamoHttpResponse. Please refer http://docs.oracle.com/cd/E24152_01/Platform.10-1/ATGPlatformProgGuide/html/s0801requesthandlingwithservletpipeli01.html