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Scripting and Performance testing with dll files

I need some assistance and guidance please.

I have been approached to performance test a application making use of dll files.

My problem is that I do not know where to start as this is completely new to me, as I have worked with HTTP/HTML/Web Services/Oracle NCA/ API's, etc.. What are the basic information I require apart from the dll files?

There are limited infrmation available on the net regarding performance testing in loadrunner using dll files.

The only information I basically gathered was to load a dll and how to call functions, etc, in the .dll do I have no idea.

Is performance testing using dll files actually possible?

What are your pre-requisites?

What would you use as you pass/fail criteria, would you receive a result code similar to a web service call?

How do you make use of unique data or input parameters if required to simulate different users,etc. ?

If you have mulitple dll files, do you need to upload each file via the lr_load_dll function?

Would you require to have all dll files stored to a directory to be used on the load generators for test execution?

Thanks in advance.


Gerrie Holtzhausen



3 Replies
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Re: Scripting and Performance testing with dll files



As I understand, you want to make a performance test an application that have the specific DLL files. If that, you can try with .NET protocol.

You can add the DLLs of your application to Vugen then start recording and these DLLs should be placed in LG machine when running the test. Please refer this link for more details about this protocol: http://lrhelp.saas.hpe.com/en/latest/help/WebHelp/Content/VuGen/139650_c_dotnet_overview.htm

You can also load the DLLs manually and customize the script by using Loadrunner functions.  Here is the links to refer:










Chau Nguyen | SW Technical Support Consultant.
LoadRunner and Performance Center

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Re: Scripting and Performance testing with dll files

Hi Chau

The problem I am facing is that I am not recording any application but the requirement is to work purely with the .dll files and create a script like this calling the different functions, etc. 

Using the .net protocol is not going to help me as I have no experience on .net and we are also not licenced for .net.

What I gather is that I will require alot of information regarding which functions to be called in which .dll as they provided me with 30 odd .dll files and a couple of .pdb (program database) files as well as xml config files.. I am attempting this blindly as I do not have any information as to which .dll need to be used when and the guys do not have any documentation to assist me with how to use these .dlls.

As it stands now, anf what I notice  is that this will not be a quick scripting and testing exercise as there are many dependencies.



Micro Focus Contributor
Micro Focus Contributor

Re: Scripting and Performance testing with dll files


As you are no doubt aware, LoadRunner provides a way to generate load on an application - typically where the application runs on a server that a client connects to. It sounds like in this case you may not be dealing with a "classic" client server type application environment but instead are possibly testing an "API" but without the API documentation. Without any documentation the only alternative is to obtain the code for a sample application, enlist the assistance of the developers of the DLL files or use "reverse engineering".

Nevertheless it should be possible to code a VuGen script that calls the functions that these DLL files implement so as to simulate (either partially or fully) the actions that an application built on these DLL files would perform. This is in effect similar to coding a script which implements a "cut-down version" of a client application, where your script only uses those functions that generate the intended load you need to test. However to do this effectively you will likely need an in-depth understanding of the functions the DLL files implement, that is, of potential applications that will use these DLL files.

As you have mentioned you have found the information on how to invoke DLL functions in a VuGen script however I suspect that you will need the documentation describing the DLL file functions or the assistance of the developer of the DLL files to effectively simulate a client in a VuGen script.

You should be able to control the pass/fail criteria using script statements however this also depends on having an understanding of the DLL file functions. You should also be able to control the data and parameters used to differentiate between VUsers.

You will need to load each DLL that is used - see the Function Reference for "lr_load_dll" for more details. All DLL files loaded will need to be available on each load generator where the script will be run.

Hope this helps,


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