IBM Content Navigator, Version 2.0.3

Creating a request or response filter

You can create a plug-in to filter a request that is made to a service or to filter a response that is received from a service. For example, you might create a request filter to modify the parameters that are sent to a service to provide custom validations and error handling. You can also create a request filter to override a service. For example, you might create a response filter to apply custom formatting to the data that is received from a service before the data is displayed.

About this task

The external data service plug-in uses request and response filters to enable a service to provide custom choice lists and validation.

To use a filter, a plug-in must handle the JSONArtifact object that is sent in the request or the JSONObject object that is returned in the response.

Important: The JSON format that is used for request and response filters is subject to change without notice. If you create request and response filters for plug-ins, you might need to make updates to your code if a new version of the IBM® Content Navigator Java™ application programming interface is released.

Procedure

To create a request or response filter:

If you are creating a request filter, extend the PluginRequestFilter class:
1. Implement the getFilteredServices method to return the names of the services for which this filter is used.
2. Implement the filter method to define the filter that is to be applied to the request.
  Tip: Examine the JSON object that is sent to the service to determine the requirements for the filter method.
If you are creating a response filter, extend the PluginResponseFilter class:
1. Implement the getFilteredServices method to return the names of the services for which this filter is used.
2. Implement the filter method to define the filter that is to be applied to the request.
  Tip: Examine the JSON object that is returned by the service to determine the requirements for the filter method.

Add the filter as a component in your Plugin.java subclass:

Type of filter	Add to the Plugin.java subclass
Request	Implement the getRequestFilters method to return an instance of the PluginRequestFilter.java class that you created in step 1.
Response	Implement the getResponseFilters method to return an instance of the PluginResponseFilter.java class that you created in step 2.

Sample plug-in files for a custom response filter

The following files in the sample plug-in define a response filter.

Table 1. Sample files that define a plug-in response filter
File	Description
SamplePluginResponseFilter.java	This file extends the PluginResponseFilter class to define a filter that applies custom property formatting to search results.