Tag Archives: JMeter

JMeter and WSSE

WSSE signing and/or encryption has always been an issue no-matter what tool you use. One of the reasons for the ongoing success of SoapUI as that does it magically somehow. 😉

Thankfully my colleague Till Neunast has now written a wrapper that allows you to use WSSE with JMeter. Just install and away you go (nearly). It is really no less complex than the SoapUI variant. It is still early days and should be treated with caution(!!) and I can imagine there still being some change to the project but it’s a very good start and a long awaited reprieve from the personal hell that WSSE has been in the past. So excuse me for being a bit overexcited.

If you do end up using the plugin please feed back any issues or improvements to the project or Till for that matter.

To download please see here:
https://github.com/tilln/jmeter-wssecurity

by
Oliver Erlewein

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My Daily Tool Use [Updated #2]

SublimeAs a performance tester I spend most of my daily time somewhere between the browser and a web server. I also so spend a lot of time on servers themselves analysing data. So I thought I’d write a bit about the tool landscape I tend to use. In my tool selection I favour Open Source software. Mainly because I don’t have to fluff around with licenses but also because I can look at code if I need to. It allows me to focus my resources on training people. I do tend to feed back into OSS, whenever I can (which is seldom as I am usually not that clever;-) ).

I also do a lot of bespoke programming to automate processes. This is not at the level a developer would do things but more on a simple scripting level. But not to be underestimated what power this can unleash in your day to day work.

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Controlling JMeter ThreadGroups with -1

When I script large JMeter projects I immediately default to run scripts through config files. That means that all sorts of variables get pre loaded at the start of the test (VariablesFromCSV is a huge help!). From there I control things like URLs, usernames and passwords,… but I also control Thread Groups. Recently I came across the issue that I wanted to switch in such a config file between a test that ran for a certain length of time to a test that ran only X number of iterations.

For all of you that have used JMeter you know that that might be an issue.

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A simple JMeter Execution Framework

GitHubFor years I have been thinking of open sourcing the work I do. I see the Blog here as a simple part of that effort. The main -selfish- reason though is, so I don’t have to carry code around from A to B and I can safeguard it from someone claiming it as their own (even me). Open sourcing is something easier said than done. Especially if things are over a certain size and the things I do are usually very tailored to the project context, which makes it difficult to generalise.

But… all things have to start small. I have released WinMinoTaur on GitHub today. These are just some small Windows batch files but they make test execution life with JMeter a bit easier. You no longer depend on the UI to execute tests.

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CheatSheet for JMeter __time Function Calls

Often I have to deal with dates and times in my scripting and luckily JMeter is quite good at dealing with them. The function to call is __time (JMeter doco http://jmeter.apache.org/usermanual/functions.html). The thing is the doco is pretty sketchy about all the different formats it can take. So I just created a test script to see what works. The examples are below ready to copy & paste. I also have included scripts for time and date manipulation for completeness.

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Extracting a value from JSON with JMeter

So again an issue I had and thought I’d share. I found very little about this on Google. The problem I had was, that I got a JSON response from a site that contained an ID I’d need to use on the next page. The challange was that I had a variable in the regex which JMeter doesn’t seem to like. The easiest way to do this is to use JMeter-plugins!!!

Short post, if it were not for the unlucky fact that I couldn’t use the plugins. So here the long answer….

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Iterating over a CSV file in JMeter

A common problem in JMeter is that you want a CSV file as an input and want to execute each line, then continue. So from a script perspective that would look something like this:

Thread Group
 |-For Each CSV Line
 |  |-HTTP Request (CSV input)
 |-Do something else

The issue though is there is no “For Each” concept in JMeter. I know that it is called a ForEach Loop in JMeter but it isn’t from a developer view. You need to know the length of your CSV file. You could just tell the For loop how many lines there are but that would make it very unflexible. You’d need to adjust the script every time the CSV changes.

So here is how I solved it. Not elegant but it actually works quite well.

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Loading File Contents Into a JMeter Variable

Sorry for the ongoing spam about JMeter stuff but I am writing a LOT of coding at the moment and I thought I’d share some of the knarly stuff I come accross so others might benefit.

So I had the issue that I need to cobble together MIME HTTP/SOAP calls that contain attachments. JMeter has the ability to add files statically to an HTTP Request (Body Data) but if you need more control you need to roll your own. Best way to do this would be to load the file into a variable and just attach like this:

...
--MIME_boundary
Content-Type: application/pdf
Content-Transfer-Encoding: binary
Content-ID: <MyFile.pdf>
Content-Disposition: attachment; name="MyFile.pdf"

${AttachmentFile}
--MIME_boundary--
...

But how do you get it into the variable?

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HMAC and SHA256 in JMeter

Some projects require authentication features that involve some quite intricate steps. But fret not, in JMeter we can use Groovy to do the heavy lifting. Below is a very simple example of how you can do a HMAC encryption. It also includes the SHA256 hashing and base64 encoding. The only thing missing are the functions to read the variables from JMeter and publish the hash to JMeter but that is trivial and you can fit it into whatever you already have scripted.

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.security.InvalidKeyException;

String secretKey = "secret";
String data   = "Message";

Mac mac = Mac.getInstance("HmacSHA256");
SecretKeySpec secretKeySpec = new SecretKeySpec(secretKey.getBytes(), "HmacSHA256");
mac.init(secretKeySpec);
byte[] digest = mac.doFinal(data.getBytes());
encodedData = digest.encodeBase64().toString();
log.info("HMAC SHA256 base64: " + encodedData);

by Oliver Erlewein