Testing Web Services in the Cloud

Testing Web Services in the Cloud

Harry M. Sneed (Independent Consultant, Germany)
DOI: 10.4018/978-1-4666-2536-5.ch007

Abstract

Cloud Computing makes it possible for users to access a wide range of web services in the public domain and to embed these global services in their local applications. This promises to save a significant amount of individual development cost. The biggest obstacle to using this technology is the problem of trust. To gain trust in the services offered they have to be extensively tested, either by the user himself or by a trusted agent. This chapter deals with the testing of web services in the cloud. There are many similarities to testing web services in a local service-oriented architecture, but there are also significant differences. In a company specific SOA, testers can gain access to the source. This is not true of the cloud. There is no possibility of accessing the source. Therefore, testers must rely solely on the specification contained in the service level agreement – SLA – and the web service interface definition – WSDL or REST – to base their test upon. Testing in the cloud is strictly a black-box test. The goal of a cloud service test is also not to find errors but to assess the suitability of the service to the purpose of the user. It may be necessary to test several services in order to find that one best suited to the requirements of the user. To judge suitability it is necessary to define an ideal usage profile, including performance, security and other non-functional criteria, and to compare that with the actual profile of each potential service. For this both static and dynamic analysis methods must be applied. The chapter presents an automated approach to assessing cloud services and selecting that one most suitable to the user’s application.
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2. Obstacles To Using Web Services In The Cloud

2.1 The Problem of Trust in Using Cloud Services

The biggest obstacle to using cloud services is that of trust. The economic rationale for using web services offered in the cloud is overwhelming, but how can users know if they can trust them. Most cloud researchers agree that there is definitely a trust problem. According to the CBDI Forum, the big issue is “will the service work every time when I need it?” That forum is concerned about the fact that too few potential users are thinking about the issues of testing and certification. It suggests that the testing and certification of web services in the cloud in not business as usual and that new approaches are needed to assure that those services can really be trusted (CBDI, 2010). In recent years a number of researchers have turned their attention to this problem and some are calling for a formal certification of public cloud services. Others, such as the author of this chapter, are calling for testing organizations to offer the testing of cloud services as a service. The goal of such a service is to offer quantitative evidence of whether a service can be trusted or not (Vossen, 2011).

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