Question on Filters and RequestDispatcher

[Radhika Gokhale]

Hi,

The Servlet spec on Page 56 explains with examples on the filter patterns and RequestDispatcher behaviour. One of the example is as follows:

<filter-mapping>
<filter-name> Logging Filter </filter-name>
<servlet-name> ProductServlet </servlet-name>
<dispatcher>INCLUDE </dispatcher>
</filter-mapping>

would result in the Logging filter not being invoked by client requests to the ProductServlet, nor underneath a request dispatcher forward() call to the ProductServlet, but would be invoked underneath a request dispatcher include() call where the request dispatcher has a name commencing ProductServlet.

Now my question is why will the Logging Filter not being invoked by client requests to ProductServlet.

Please clarify. Also I have not used Filters in actual programming and want to know how many questions should I expect on it.

Thanks in advance.

Radhika

[georgy jacob]

As the dispatcher mechanism is mentioned as "include" only include calls will trigger the filter.It will not be invoked for normal client requests.


Thanks,
georgy