Maintaining data consistency in XML-based applications

We have witnessed an increasing number of Web-based applications that use eXtensible Markup Language (XML) as a data format. This fact has resulted in a high demand for better XML data stores. One issue of managing XML data storage that still needs to be addressed is the impact of update operations toward the consistency of the linked XML data. It is widely known that in XML-based applications, persistent references also avoid broken links and invalid search engine results. The current solution is done by regularly checking the broken links and manually rectifying any that are found. This of course requires a considerable effort. Our aim in this work is to avoid the broken references/links in the first place by checking before updating a document. In this work we propose new methodology to maintain the consistency of XML data after update operations, which can be classified into insertion, deletion and replacement. The methodology is taking form as a set of functions that perform checking mechanism before an update. The methods are applicable for schema-based and also non- schema based XML data. For implementation we apply the methods into a set of functions in XML-enabled database and in native XML database.