Load Testing using Service Virtualization

This is pretty interesting stuff that i have been working on-

First lets understand basics of Service Virtualization (SV)- In the later posts we will cover the Load Testing approach.

What is Service Virtualization?

Service virtualization involves the imaging of software service behavior and the modeling of a virtual service to stand in for the actual service during development and testing. Service virtualization is complementary to hardware virtualization, and provides a solution to address each of the aforementioned hardware virtualization limitations such as:

1. Providing 24/7 access to the service end point on your terms
2. Removing capacity constraints
3. Addressing data volatility across distributed systems
4. Reducing or eliminating the cost of invoking 3rd party systems for non-production use

So how does it go well with different application? What are the constraints?

Here are some constraints which Service Virtualization can overcome-

Access to a mainframe:
There are dozens of project teams, each needing access to the mainframe. Yet these teams receive very limited access, and often during timeslots that do not align to their project plan. This is a persistent problem that introduces risk, unacceptable delays, lost productivity and added cost.

Access to a database:
Another team owns a database that is accessed by others. This database is currently accessible in a development lab, but one team needs a new stored procedure added to that database. It may take 3 or 4 months with the DBA team in order to deploy those stored procedures.

Access to the web service:
There is a legacy system deployed and due to an architectural mandate, access to legacy system functionality will be provided via web services. However, no web service is available to test against, and not even an individual responsible for creating the web service.

How does SV works?

Following diagram can help us understand the basic on how SV can be captured?

As you can see in the above diagram-

A "service image" as a part of service virtulaization can be captured by some external tool during recording.The request and response of the application can be captured as a part of  service image.This service image then later be hosted and deployed on some server.The SI will then service the all the requests and send appropriate responses. This way when you run your script you are not hitting the actual site but just the Service Image !

Most of the tools available in the market has ability to work with common protocols listed below-

Transport protocol (Interface Protocol)
HTTP / HTTPS (Web Applications)
JDBC (Databases)
Messaging platforms (webmethods, Tibco, MQ, Sonic, JCAPS)
Standard JMS
From WSDL for HTTP / s

Data Protocol

HTTP Traffic (Web)
Web services (SOAP)
Protocol layer for handling messages over IBM MQ
Protocol layer for handling messages over JMS using JNDI

Available tools in the market?

If you do Google you will find many tools which can do SV. My personal favourite is ITKO LISA. Please find more information here.

Quick Start and Check- Script Recording in HP LoadRunner

Few useful pointers/Smoke Start - Script Recording in HP LoadRunner.

1) For a typical business scenario with login-action-logout,try recording Login part in Vuser_init, action part contains the actual functionality / navigation to be performance tested and Vuser_end contains the logout part. This enirely depends on the business scenario.It is also possible that you may record something else in vuser_init() as per your business requirement. As per good practice ensure proper transactions, comments are included in the script.

2) Once script recording is complete, replay the script with extended logging and data returned by Server enabled. This will help you identify any dynamic values which are returned by Server. Accordingly you would have to correlate the dynamic values.

3) Correlation - You can enable Auto-correlation if you are not comfortable with LoadRunner. But Autocorrelation may fail at times, hence Manual correlation is always preferrable.

4) Incase correlation is also complete, parameterize values like UserId, Passwrod and fields which would change for every iteration.Make sure you proper commnets in your scripts defininf what all changes you have made.

5) Once script enhancement is complete, execute the script for minimum 2 iterations in VuGen. Check whether all transactions pass.Check all the logs for any missing or broken links.

The above points will ensure that your first step is correct.Later in the script you can add more complex enhancements.

How to clear HP AIS - Loadrunner v11 certification?

There are few pointers that i would like to mention,these are essentially for people who aim to appear for HP AIS - LoadRunner v11 certification-

1. HP AIS Load Runner V11 consist of two papers-

Exam HP0-M48: HP LoadRunner 11.x Software
Exam HP0-M49: HP Virtual User Generator 11.x Software

Questions are multiple type with no negative marking. You get sufficient time to attend questions.You will need to clear both the papers in order to get certificate.

2. What to expect in question papers-

Exam HP0-M48: HP LoadRunner 11.x Software-In this paper questions are related to the LR software.Therefore it is important for candidate to have some hands on experience on LR. Questions range from navigation to listing of menu items. Unless you have seen the software thoroughly (and able to recollect) it would be hard answer questions. Questions where you get to see two or more graphs merged,and you are required to tell what kind of graph it is.Typically there are predefined graphs like layover and all in LR.

Exam HP0-M49: HP Virtual User Generator 11.x Software- In this paper questions are mostly related to run time settings,scripting and practical approach towards a problem.There will be a code snippet and user is expected to tell the output.

3. I will try to incorporate some sample questions in the next post.

Please feel free to contact me on - abhayanand.bhagwat@gmail.com

Cheers.