Data change notification (DCN) requests need not always be in the format Unwired Server expects.
You can deploy a DCN filter to Unwired Server and reference it in the DCN request. Unwired Server allows the filter to preprocess the submitted DCN. The filter converts raw data in the DCN request to the required JavaScript Object Notation (JSON) format. The filter can also postprocess the JSON response returned by the Unwired Server into the format preferred by the back end (which is governed by the implementation in the filter class).
The filter interface DCNFilter is in the com.sybase.sup.server.dcn package in the sup-server-rt.jar file. All classes that implement a DCN filter should implement this interface. The functions available in the interface are:
- String preprocess(String blobDCNRequest, Map<String, String requestHeaders> requestHeaders); – takes the DCN request as a binary large object (BLOB), converts it into a valid JSON DCN request format, and returns the same.
- String postprocess(String jsonDCNResult, Map<String, String responseHeaders> responseHeaders); – takes the DCN result in a valid JSON format, converts it to the EIS-specific format, and returns the same.
- Changed data is sent from the EIS to Unwired Server via a DCN request, where any data preprocessing occurs. For example, the EIS data could be sent to Unwired Server as XML where the preprocess filter converts the data to JSON.
- The DCN executes. For example, apply data changes directly to the Unwired Server cache.
- Postprocessed DCN response is sent to the originating EIS as an HTTP response to the original DCN request. For example, the JSON response is converted to XML.