Abstract

 

With the popularity of Web Services technology and the increase trend of developing Service-Oriented Architecture (SOA) software, there is a need for an implementation methodology for Web Services. This paper addresses the SOA application development challenges, identifies gaps in agile software methodology for Web Services development, and observes Web Services characteristics and its best practices. The contribution of this paper is to extend any existing agile software methodology to include Web Services Best Practices into the agile software methodology.

 

Introduction

The Service-Oriented Architecture (SOA) is a software architecture that defines the use of services, to support software user requirements [2]. The characteristics of these services are reusable business components; loosely coupled; building blocks of SOA application with the intent to provide services to either end user applications or other services through published and heterogeneous network addressable software component.

 

The implementation of SOA application is made possible through the realization of Web Services. Web Service is a software component representing specific set of business functions that can be described, published and invoked over the Internet using XML-based open standards such as SOAP [3], WSDL [4] and UDDI [5]. The SOA application development involves developing software components for software reuse and wrapping software components as Web Services for end user applications or other services consumptions. However, there are gaps in the existing software component development methodology as it does not include the design and development factors specific for Web Services.

 

This paper discusses the research work done in bridging the gaps by investigating the characteristics and the best practices of Web Services development. The outcome of the research work is part of the specification developed for OASIS Framework for Web Services Implementation (FWSI) [13] Implementation Methodology Sub- Committee [15] (IMSC) in the effort to develop implementation methodology for Web Services.

 

SOA Application development challenges

 

In a dynamic digital economy, the demand for direct process integration to business partners from organizations and sharing of information is increasing. Organisations are gradually turning to SOA application to increase their business agility and IT productivity. The building blocks for SOA application come from different service providers. The SOA application development process is complex and tedious. It requires proper software project management planning and control to ensure systematic approach for handling and developing SOA application. This is attributed to the fact that some of these building blocks of services are outside companys boundary. The confronted challenges for SOA application development are:

 

1. Difficulty in capturing of user requirements as the requirements no longer derives from a single source. It can come from multiple stakeholders who may be geographically distributed.
2. Difficulty in collating different services as not all the services are implemented using the same technology. Some services could be implemented using C++, C#, Java, PERL, etc. The hosting of services on different technology platforms also contributed to the collating difficulties.
3. Difficulty in services consumption due to different types of services provided. Some services only support asynchronous interaction; some may support synchronous interaction, etc. This poses difficulty in SOA application.
4. Difficulty in services communication because of different interfaces, e.g. document-oriented message exchange; parameters-oriented message exchange, supported by different services.
5. Different services offer different degrees of service coupling. Document-based services are more loosely couple than non document-based (i.e. parameter-based) services.
6. Complicated task in conducting SOA application test as it requires a well-coordinated effort from all services providers to ensure all services are available.