Web Services and QTP – Part 1: Testing Web Services Key Concepts

W3C defines – A Web service is a software system designed to support interoperable machine-to-machine interaction over a network. It has an interface described in a machine-processable format (specifically WSDL). Other systems interact with the Web service in a manner prescribed by its description using SOAP messages, typically conveyed using HTTP with an XML serialization in conjunction with other Web-related standards.

Testing web services is no different than testing any other application/software program, but there are some unique challenges.

Web service based architecture is intrinsically distributed and is dependent on various stakeholders, which makes it difficult to establish availability and quality of service across the various stake holders. Most likely Web Services could be dependent on third party web services. And these third party web services can be changed without any information

Web services in an inter-enterprise SOA are so loosely coupled than the traditional architecture that tracking message route between different Web service stake holders is difficult.

Web services testing is basically the validation of interface points, messages and message formats which is quite different from testing the GUI.

Testing tools which are using GUI based automation is simply inadequate for Web services testing, but we don’t have to worry too much as we have QTP. Ian Fraser has well said it -

“The true beauty of QTP is that the only limitation is your imagination and ability to code in VBScript.”

HP Service Test and QTP Web Services Add-in are great solutions for Web Services testing. HP Service Test Management module plugs into Quality center. We need QTP Web Services add-in in order to work with web services which can be downloaded from HP Download Center.

Let us first understand web services key points need to know before delving into testing with QTP. Typically a Web Service is a set of all related functions which are invoked to other application or services over the Internet. The information to programmatically invoke a Web service by an application is given by a Web Services Description Language (WSDL) document. Web Services Description Language (WSDL) is an XML-based language for locating and describing Web services. Now as the Web Service is powered by the web application server that uses SOAP to understand and speak with web services and delivers information in XML. Simple Object Access Protocol (SOAP) is XML based protocol to exchange information over HTTP. To locate the web services WSDL documents are indexed in searchable Universal, Description, Discovery and Integration (UDDI) business registries.

“inurl:wsdl site:w3schools.com”

you will find the public example web service provided by W3C. On accessing the WSDL (http://www.w3schools.com/webservices/tempconvert.asmx?wsdl) you will come to know about the access points and interfaces available for the web service. Something like the snapshot below –

This web service has two methods ‘CelsiusToFahrenheit’ and ‘FahrenheitToCelsius’ and simply takes the temperature and converts it to the required.

There is one most important element in WSDL, which is Port. WSDL Port defines the connection point to a web service. It can be compared to a function library or a module or a class in traditional programming language.   You can find the service name and port in below section of WSDL.

You can understand this Web Service better when you will navigate to the W3C web service example , where you can see the interface for the web service.

If you click any of the two operations there it shows you the form to input parameters required for the operation and invoking this will give you the result in XML.

Just below the form you will see sample SOAP request and response, which is actually processed when the web service is invoked.

SOAP Request

SOAP Response

The ‘string’ (in blue) that you see is actually replaced by the value that you process.

So now you must be ready to start testing this in QTP.  We will see the various intricacies of web service testing with QTP in the next part.