Sun Java System Web Server extends the Netscape Server Application Programmer's Interface (NSAPI) to support NSAPI filters.
Filters enable the custom processing of HTTP request and response streams. This allows a function to intercept and potentially modify the content presented to or generated by another function. For example, a plug-in could install a NSAPI filter to intercept a XML page generated by another plug-in's Server Application Function (SAF) and then transform that XML page into a HTML, XHTML, or WAP page appropriate for the client. Alternatively, a NSAPI filter could decompress data received from a client before presenting it to another plug-in.
For more information, see Sun Java System Web Server 6.1 SP6 NSAPI Programmer’s Guide.