Keywords: web services, finite element method, service-oriented architecture, XML, SOAP, WSDL, UDDI, engineering software.

In this paper, an Internet-enabled prototype finite element system is presented that represents the initial work of an ongoing project. The system builds upon a design of an existing component-oriented finite element system [1]. One of the goals in the design and implementation of the existing system was to provide a component-oriented framework of interfaces and services that would enable software developers to easily modify and extend the system without recompilation or re-initialization of the existing services.

The prototype extends the existing system by taking advantage of the Internet and web-based technologies. It is implemented based on Web services technology. The term Web services describes an important distibuted computing paradigm that differs from other approaches, such as DCE, CORBA, DCOM, and Java RMI in its focus on simple, Internet-based standards (e.g. eXtensible Markup Language: XML) to address heterogeneous distributed computing. Web services define a technique [2] for describing software components to be accessed (Web Services Description Language: WSDL) [3], the methods for accessing these components (Simple Object Access Protocol: SOAP) [4], and the discovery methods that enable the identification of relevent service providers (Universal Description, Discovery, and Integration: UDDI) [5].

• CoFFEE-online. Services for the Internet access to the existing structural analysis program CoFFEE. A web portal was built that enable online analysis.
• CoFFEE-WS. Specifications and a set of services that allow researchers to build specialised service-oriented distributed applications for structural analysis using the finite element method. Services provided by the system include: element services, material services, solutions strategies services, solver services, and other analysis services.

The services were developed using different programming languages (Java, C#) and operating systems (WindowsXP, GNU/Linux). One of the implementation goals of the prototype was to leverage existing software programs (solvers, mash generators, ...) as much as possible. Where possible, only simple wrapper web services were implemented to facilitate distributed access to the underlying programs.

Implemented services run on a variety of computer systems ranging from usual 1 GHz desktop systems running element services to computational clusters running solver services. Though the range of tests was limited, it is concluded that:

• Efficiency of the CoFFEE-online is comparable to the original software system as expected. Level of network communication between a client and the CoFFEE-online server is very low.
• While a lot of attention has been made during the design phase of the development of the CoFFEE-WS services and specifications to minimise network communication between different services, the performance of the implemented prototype systems is not acceptable for a daily use.

The long term goal is to develop a complete service-oriented finite element analysis platform based on the web service technology. A very basic prototype implementation has been described in this paper; the future software engineering developments are perhaps of greater interest. This may include developing services for a dynamic finite element services location. This service could use knowledge-base techniques and different ontologies to help the end users build customised finite element analysis solutions.

The prototype system relies heavily on stable network connections and does not provide any fall-back mechanisms in case of unavailability of requested services. The issues of authentication and security are also not addressed. These issues could be addressed in the network level, especially by utilizing the Public Key Infrastructure (PKI) that supports digital signatures and other public key-enabled security services [6].

1

M. Dolenc, "Developing Extendable Component-Oriented Finite Element Software", paper 8 in Proceedings of The Third International Conference on Engineering Computational Technology, Prague - Czech Republic, 4-6 September 2002, Civil-Comp Press, 2002. doi:10.4203/ccp.76.8

2

World Wide Web Consortium, http://www.w3.org/2002/ws/.

3

World Wide Web Consortium, http://www.w3.org/2002/ws/desc/.

4

World Wide Web Consortium, http://www.w3.org/2000/xp/Group/.

5

OASIS, http://www.uddi.org.

6

W. Stallings, "Cryptography and Network Security: Principles and practice", 2nd Ed., Prentice Hall, NJ, 1998

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