Input

All Input directives are executed when the server or a plug-in first attempts to read entity body data from the client.

The Input stage allows you to select filters that will process incoming request data read by the Service step.

NSAPI filters in Sun Java System Web Server 6.1 enable a function to intercept (and potentially modify) the content presented to or generated by another function.

You can add NSAPI filters that process incoming data by invoking the insert-filter SAF in the Input stage of the request-handling process. The Input directives are executed at most once per request.

You can also define the appropriate position of a specific filter within the filter stack. For example, filters that translate content from XML to HTML are placed higher in the filter stack than filters that compress data for transmission. You can use the filter_create function to define the filter's position in the filter stack, and the init-filter-order to override the defined position.

When two or more filters are defined to occupy the same position in the filter stack, filters that were inserted later will appear higher than filters that were inserted earlier. That is, the order of Input fn="insert-filter" and Output fn="insert-filter" directives in obj.conf becomes important.

The following Input-class functions are described in detail in this section:

• insert-filter adds a filter to the filter stack to process incoming data.

• match-browser matches specific strings in the User-Agent string supplied by the browser, and then modifies the behavior of Sun Java System Web Server based upon the results by setting values for specified variables.

• remove-filter removes a filter from the filter stack.

• set-variable enables you to change server settings based upon conditional information in a request, and to manipulate variables in parameter blocks by using specific commands.

insert-filter

Applicable in Input-class directives.

The insert-filter SAF is used to add a filter to the filter stack to process incoming (client-to-server) data.

The order of Input fn="insert-filter" and Output fn="insert-filter" directives are important.

Returns

Returns REQ_PROCEED if the specified filter was inserted successfully or REQ_NOACTION if the specified filter was not inserted because it was not required. Any other return value indicates an error.

Parameters

The following table describes parameters for the insert-filter function.

Example

Input fn="insert-filter" filter="http-decompression"
        

The above directive instructs the insert-filter function to add a custom filter, that is, http-decompression to the filter stack. The http-decompression filter will decompress the incoming HTTP request data, before it goes to the service stage. For more information about predefined filters, see Input and Output. For more information about creating custom filters, see Chapter 4, Creating Custom Filters, in Sun Java System Web Server 6.1 SP10 NSAPI Programmer’s Guide.

match-browser

Applicable in all stage directives. The match-browser SAF matches specific strings in the User-Agent string supplied by the browser, and then modifies the behavior of Sun Java System Web Server based upon the results by setting values for specified variables. See match-browser.

remove-filter

Applicable in Input-, Output-, Service-, and Error-class directives.

The remove-filter SAF is used to remove a filter from the filter stack. If the filter has been inserted multiple times then only the topmost instance is removed. In general, it is not necessary to remove filters with remove-filter, as they will be removed automatically at the end of the request.

Returns

Returns REQ_PROCEED if the specified filter was removed successfully, or REQ_NOACTION if the specified filter was not part of the filter stack. Any other return value indicates an error.

Parameters

The following table describes parameters for the remove-filter function.

Example

Input fn="remove-filter" filter="http-compression"

         

set-variable

Applicable in all stage directives. The set-variable SAF enables you to change server settings based upon conditional information in a request, and to manipulate variables in parameter blocks by using specific commands. See set-variable.