Secure DP Service Composition with Query Optimization

Data providing services provide bridges to query enterprise data sources. However In most cases user's queries require the composition of several services. The RDF based query rewriting algorithm is used for DP services composition which has limitation that, it is unable to provide security for a confidential data which is represented in RDF graph. Hence the proposed system will use RDF Encryption in which confidential data in a RDF-graph will be encrypted for a set of recipients while all non-sensitive data remain publicly readable. Integrated access to multiple distributed and autonomous RDF data sources is a key challenge for many semantic web applications. As a reaction to this challenge, SPARQL, the W3C Recommendation for an RDF query language, supports querying of multiple RDF graphs. However, the current standard does not provide transparent query federation, which makes query formulation hard and lengthy. Furthermore, current implementations of SPARQL load all RDF graphs mentioned in a query to the local machine. This usually incurs a large overhead in network traffic, and sometimes is simply impossible for technical or legal reasons. To overcome these problems we propose query optimization technique, which will also reduce the execution cost.