Online View Maintenance for Continuous Query Evaluation

In Web stream processing, there are queries that integrate Web data of various velocity, categorized broadly as streaming (i.e., fast changing) and background (i.e., slow changing) data. The introduction of local views on the background data speeds up the query answering process, but requires maintenance processes to keep the replicated data up-to-date. In this work, we study the problem of maintaining local views in a Web setting, where background data are usually stored remotely, are exposed through services with constraints on the data access (e.g., invocation rate limits and data access patterns) and, contrary to the database setting, do not provide streams with changes over their content. Then, we propose an initial solution: WBM, a method to maintain the content of the view with regards to query and user-defined constraints on accuracy and responsiveness.