Load Testing Web Services

A Few Concepts

Nowadays, more and more applications use web services (https://en.wikipedia.org/wiki/Web_service) for several reasons:

• To adapt to new constraints
• To interface mobile applications
• To interface heterogeneous systems in distributed environments
• To provide services to partners
• To avoid tying interfaces to a particular library in a specific language, and so on

This service is frequently used, particularly with the success of microservice architectures (https://en.wikipedia.org/wiki/Microservices). Under the term "web services," several technologies exist, such as WS-\* web services and REST web services. Let's look in more detail at these two technologies.

REST (REpresentational State Transfer) Web Services

To meet certain needs (such as a lower complexity of implementation, reducing the volume of data exchanged and reducing the parsing cost, particularly for mobile applications, and more), REST...

A Few Concepts

Nowadays, more and more applications use web services (https://en.wikipedia.org/wiki/Web_service) for several reasons:

• To adapt to new constraints
• To interface mobile applications
• To interface heterogeneous systems in distributed environments
• To provide services to partners
• To avoid tying interfaces to a particular library in a specific language, and so on

This service is frequently used, particularly with the success of microservice architectures (https://en.wikipedia.org/wiki/Microservices). Under the term "web services," several technologies exist, such as WS-\* web services and REST web services. Let's look in more detail at these two technologies.

REST (REpresentational State Transfer) Web Services

To meet certain needs (such as a lower complexity of implementation, reducing the volume of data exchanged and reducing the parsing cost, particularly for mobile applications, and more), REST web services appeared. REST web services are based...

Setup with JMeter

Again, JMeter allows us to easily test web services. We can do it using HTTP Request:

Figure 8.2: HTTP Request

Do not forget to add an HTTP Header Manager with the correct parameters (here, Content-Type is equal to text/xml; charset=utf-8):

Figure 8.3: HTTP Header

Note

Note that JMeter provides the Building a SOAP WebService Test Plan template to speed up the configuration.

Figure 8.4: Building a SOAP WebService Test Plan template

To help us, we can use the excellent SoapUI (https://www.soapui.org/), which generates the message content of our call to the web service from the WSDL.

It even makes it possible to create Mock servers of the web service, allowing us to test it while its implementation is not yet available.

If your teams have already run tests with SoapUI, Postman (https://www.getpostman.com/), Swagger (https://swagger.io/), or any other similar tool, you can save a lot of time by setting JMeter as a proxy in these tools. JMeter...

Methodology

As we have just seen, there is much in common between testing a web service and a web server. This is why the recommendations in Chapter 7, Load Testing a Website apply here. Note that it is important to monitor the volume of data sent by web services. Indeed, messages can be quite verbose, so they can be the cause of performance problems.

Practice with JMeter

Let's move on to practice.

SOAP/XML-RPC Web Services

Our test application will be a web service named Calculator (an example provided with Netbeans 8.2):

Figure 8.5: Calculator

Let's use HTTP Request and add in the Path and Body Data our call to the CalculatorWSService web service:

Figure 8.6: Web Service Call

Do not forget to add an assertion to control our response:

Figure 8.7: Result control

Here, we check that there is no exception returned by the web service.

Our test plan will look like this:

Figure 8.8: Test Plan

And, the result of the execution is:

Figure 8.9: HTML Source Formatted rendering

Note

Here, we used HTML Source Formatted rendering for a better presentation of the answer. XML rendering is also possible.

You can see the result of a call to the web service, CalculatorWSService, which makes an addition of 5 and 8.

To make the dataset as large as possible, we'll use the __Random function...

Conclusion

As you can see, the web services test looks a lot like a web application test, because both are based on the HTTP protocol. Everything you learned in Chapter 7, Load Testing a Website is also valid for this chapter.