Web Service that Composes Web Services

Posted on by : admin Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,

Fulfillment of highly dynamic requirements demands the adoption of new processes and facilities for software developers. On one side, composition of web services is a process that facilitates interenterprise applications in order to fulfill the requirements. On the other side, UML has been widely used in software development. Therefore, some UML modeling diagrams for web services composition processes have the advantage that software developers are acquainted with the notation.

However, tools that implement UML diagrams must evolve in order to support web services composition. A tool that models UML activity diagrams for web services composition with its parser built as a web is described in this paper. The idea of the paper is to propose software development tools seen as polymorphic entities.

A test plan based on the IEEE 829-1998 standard was defined to test the system. A set of 15 test cases were developed in order to evaluate the correct construction of the model, to test the correct generation of the BPEL text and the correct execution of the web services participating in the composition process. All test cases resulted as expected. 12 test cases realized the composition process correctly, 3 cases failed to realize the process, the reason for this is that instructions guiding the composition process were not followed accordingly.

In two of them the user did an incorrect model and the generated BPEL code was incorrect and could not be validated to be input to the composition engine. In the other case the user inserted defects at the moment of defining partner links and variables data.

The system described in this paper proved to be useful in composing web services. The UML activity diagrams notation was also very supportive in modeling the composition process, since the composition is straightforward from the activity diagrams. The architecture of the system provides itself a service based evaluation parser allowing the possibility of extending the visual notation, and at the same time making it available for several users.

This is a step forward for building facilities for software developers such as making tools available fast and at low cost. Future work is related to the study and implementation of all the constructs of BPEL. Also, the aggregation of other notations for web services composition and selection.