Fail-Safe Operation

Usage Engine is a “workflow” based usage data mediation system that guarantees that all data will be secured in case of a system/network failure.During stream execution, transaction state is exchanged between stream and the deployment controller to maintain the transactional integrity –restart at failure point without data loss or duplication.

A transaction is referring as a unit of data (for example,a file) being processed by a stream.If a stream fails during a transaction, the stream is aborted and all data is secured. Once the stream is restarted, a rollback is triggered to clean up incomplete transactions. The execution restarts from the last successfully processed transaction in the stream. This feature is referred to as Transaction Safety.

For example, consider a stream that will process 5 files from the data source. If the first 3 files are successfully processed and there are some errors occur while processing the 4th file, causing the stream is aborted. With the Transaction Safety feature, the progress is saved for the stream. When the stream is resumed, the processing will continue from after the last successfully processed file, i.e., from the 4th file.