Performance testing of citrix with hp loadrunner

Software Testing Specialists

White Paper

Performance Testing of Citrix Applications using HP LoadRunner.

Abstract The complexity of Citrix protocol with its latest cutting edge security features has to be addressed through a detailed understanding of Citrix ICA protocol, how it works under the hood, simulation procedure, steps to address Replay issues, handle concurrent test execution issues, random/parameterized data handling mechanisms. This paper is to address such key issues and our learnings on how to handle such issues. HP LoadRunner is our tool of choice for Performance testing of Citrix applications through its sophisticated built-in support and capabilities for Citrix ICA protocol.

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Executive Summary IT landscape has seen a transformation from remote terminals to mobile/tablet based access, work in offices to work from home or work from anywhere through remote access and virtualization technologies.

The obvious need is for secured access to corporate sensitive resources, applications and data with minimal network overheads, rich UI experience and high performance computing. Citrix with its 20 years of rich innovation experience has shown the direction and solution through its ICA technology.

The ICA protocol with image/media as a means of communication channel with highly advanced security landscape ensures users have effective remoting solutions to accomplish their tasks. Applications designed with various protocols like HTTP/ HTTPS/UDP/etc. are hosted on Citrix server so that users have seamless access to their remote applications through a highly secured means.

However, the key area to be addressed – workload modelling and performance testing of Citrix applications is not an easy journey and requires a thorough understanding of the Citrix ICA protocol.

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ICA Protocol – How it works under the hood

Figure 1: Login Initiation

Figure 2: User Authentication

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How Citrix Works (a very simple flow with ICA described) Client sends a request to the Citrix Server. Request will reach the server as an image with X & Y coordinates.

Server returns a response with generated ICA file (as in image 1) with login screen.

User will login to the application with credentials, which is sent as an image to server.

Citrix extracts the user credentials from image and sends it to application.

Application authenticates the valid user and sends Home page as response.

Citrix sends Home page response as an image back to user.

Above description gives simple authentication work flow and inner working details of Citrix server. We will now discuss on how Citrix performance testing can be handled through HP Load Runner. We will also describe key challenges and solutions to overcome performance testing of Citrix protocol.

How Citrix Works with Load Runner LoadRunner is able to use the Citrix client to talk with the Citrix server and record the traffic going back and forth. The script that LoadRunner generates makes use of bitmap synchronization. It is able to sync bitmaps based on a hash value that LoadRunner creates. A bitmap is an uncompressed image file that is a two dimensional array of pixel information. LoadRunner has an algorithm that takes this pixel information and creates a hash value based on this. When the script is rerun, if the bitmap looks the same as before, the hash value will be the same, and thus the sync will work. Besides bitmaps, the LoadRunner Citrix protocol makes use of keyboard input and x and y coordinates (to know where to click or sync).

Challenges, Learnings and solutions Basic things to check prior to Citrix script development Disable DEP in Vista DEP or No Execute Protection will be a vital part of vista security. During these early builds, however, it can lead to many explorer crashes while recording using load runner.

Challenges while recording scripts Using mouse clicks while recording is not a good idea since if the screen shows on a different location (due to caching or resolution change) the click will not be in the needed field.

For that reason we need to use the tab button. Also make sure that we clean the values in each field with tab into the field and pressing CTRL A and then DEL. In this way the value of the field is emptied. If we do not do so, the text will be inserted instead of overwriting the value already in the field.

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For expandable submenus, click on each menu/submenu in order to display the submenu on playback.

Multiple sessions per user/client -- ensure if you are going to run more than one Citrix VUser on a generator (which is usually the case) -that your Citrix administrators have not restricted the Citrix server to restrict each user to have only one Citrix session available. A simple test for this is to launch the application outside of VuGen a second and third time, to confirm it is possible.

Citrix transactions, Citrix windows and bitmap functions in LoadRunner take time to stabilize and hence we must not ignore think time when replaying the script.

When selecting a row in the table, use the down arrow key to select an entry.

Citrix protocol does not record mouse movements, only the mouse clicks.

Challenges while debugging VUsers in Controller: Before load test, verify that the Citrix resolution for all the load generators is the same (as the computer where the script is recorded) before running the script.

Machines running Citrix VUsers may be limited in the number of VUsers that can run, due to the graphic (GDI) resources available on that machine. To increase the number of VUsers, open multiple Terminal Server sessions to the load generator machine and relate each terminal server session to the load generator.

This means a Terminal Server must be running on the load generator. Windows 2000 Server and Advanced Server both come with Terminal Server. If you are not using one of these OS, then please contact Microsoft on how to purchase Terminal Server separately. Please follow the instructions below: NOTE: Any ctrx_sync_on_bitmap that is recorded using a non-256 color setting will fail on replay on a terminal session. For further information, refer to Bitmap Sync Information section.

Set the ‘CitrixIsActive’ option: A. For LoadRunner7.8 or above: On each load generator box, go to Start Programs LoadRunner Advanced Setting Agent Configuration, and enable the checkbox for ‘Enable Terminal Services’

If some of the Citrix Vusers are failing in the Controller/Tuning Console, there is a way to show the Citrix client during replay: Use the – lr_Citrix_vuser_view command line:

For Controller, A. Go to the Design view, click on Details more.

B. In the field where it says “Command line”, enter – lr_Citrix_vuser_view.

This will bring up a Citrix client on the load generator box for each running VUser.

This is ONLY recommended for debugging purposes, as bringing up a client for each VUser will consume additional resources on the load generator box.

For Tuning Console, A. Right mouse click on the script, and select ‘Script Details…’

B. Under the Parameters tab, enter lr_Citrix_vuser_view as a parameter name, and 1 as the parameter value

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ƒƒ Test and make sure you can connect and run 1 Vuser on each load generator before running the full load test.

NOTE: If your script contains ctrx_sync_on_bitmap functions that were recorded on a desktop that has a non-256 colors setting (such as 16-bit or 32-bit), the function will fail on replay through the terminal session. For further information, refer to the Bitmap Sync Information section.

Below is a schematic diagram of the overall architecture of a Citrix load test.

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Best Practices Reset the connection if a user disconnects from the Citrix session without logging off. If the server is not configured this way, then there will be a lot of remaining idle sessions on the server during load test. Below are instructions on how to configure the server to reset the session (this is taken from the latest Citrix document): A. Open the “Citrix Connection Configuration” dialog box by going to Start  Programs Citrix MetaFrame XP Citrix Connection Configuration.

B. Double-click on the “ica-tcp” connection name. The “Edit Connection” dialog box appears.

C. Click on the “Advanced” button. The “Advanced Connection Settings” dialog box appears.

D. Uncheck the “inherit user config” checkbox and change the list box entry for “On a broken or timed-out connection” to “reset”.

See the “Tips for Working with Citrix Vuser Scripts” section in the Loadrunner -Citrix documentation for recording, replay, and debugging tips.

Replay your script with ‘Replay think time as recorded’. This will help to ensure that the script replay will wait for x amount of time for the windows to come up before executing the next step.

Authors: Archana Ampula & Ramesh Singamsetty are QA specialists (Performance Engineering) with strong testing and QA experience across various applications, technology and areas. They both share a passion towards resolving technological challenges within complex areas (like Citrix ICA protocol, UDP, etc), conducting assessments for testability of complex solutions and delivering successful engagements.

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