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From Andrey Pokhilko <>
Subject Re: JMeter DSL discussion
Date Wed, 10 Aug 2016 18:37:37 GMT

Thanks for so detailed explanation.

As a side note, did you see Taurus project (,
which tries to bring some YAML-based way to express JMeter test plans?

Andrey Pokhilko

On 08/10/2016 08:49 PM, Epp, Jeremiah W (Contractor) wrote:
>> -----Original Message-----
>> From: Philippe Mouawad []
>> Sent: Thursday, July 28, 2016 4:37 PM
>> To:
>> Subject: Re: JMeter DSL discussion
>> I think DSL has 2 important advantages:
>> - It is more readable in source repositories.
>> - it is better for developers who load test their application in CI/CD.
>> This is clearly an important move JMeter must follow.
> If I might chime in on this conversation?   I'd like to offer the
> perspective of an organisation actually using JMeter with CI right now.
> To preface, we're doing something rather unusual in that we're actually
> generating test plans in CI from our functional tests using a command-line
> recorder daemon I wrote (based on JMeter; I'm still trying to get permission
> to release the source) and then correlating them with post-processing
> scripts.
> In this capacity, we would be VERY interested in the ability to record to
> and operate on a format that is not JMX.  From our perspective, a robust and
> well-considered test plan DSL brings two major advantages to the table:
> determinism and structural soundness.
> By determinism, I mean that every node of the test plan tree is consistently
> represented.  By structural soundness, I mean that every relationship
> between nodes arises as a result of the structure expressed in the test plan
> file itself (i.e. implementation details don't create implicit structure).
> To elaborate further, currently, test plans are written to JMX files.  JMX
> is an XML-based format which, if you look at its actual structure, is
> moderately insane, horrendously verbose, and basically undocumented.  After
> several months of working with it, I believe it's better to consider it a
> serialisation of a Java data structure that happens to be in text form more
> than an actual file format.  I would personally love nothing more than to
> see it deprecated.
> If you haven't looked recently, I'll recap: most testElements use stringProp
> and friends with a name property to configure their nodes, and the
> parent/child relationship between most elements is implicit, relying on the
> hashTree immediately following it in the file.  The actual tree-like nature
> of an XML document is largely ignored in many cases within the format.
> (Also, again, it's XML, so there are invalid characters, which is bad.)
> For example, this is the structure of a single HTTP request with one
> Argument (and some of my own comments):
>         <HTTPSamplerProxy guiclass="HttpTestSampleGui" testclass="HTTPSamplerProxy"
testname="9952 /as/authorization.oauth2" enabled="true">
>           <elementProp  name="HTTPsampler.Arguments" elementType="Arguments" guiclass="HTTPArgumentsPanel"
testclass="Arguments" enabled="true"> 
>             <collectionProp name="Arguments.arguments">
>               <elementProp name="state" elementType="HTTPArgument"> <!-- Note
the redundancies, particularly the names -->
>                 <boolProp name="HTTPArgument.always_encode">false</boolProp>
>                 <stringProp name="">state</stringProp>
>                 <stringProp name="Argument.value">${state009951}</stringProp>
>                 <stringProp name="Argument.metadata">=</stringProp>
>                 <boolProp name="HTTPArgument.use_equals">true</boolProp>
>               </elementProp>
>             </collectionProp>
>           </elementProp>
>           <stringProp /> <!-- I'll omit all the attributes and values from here
onward; I think you get the idea -->
> <!-- Nine more stringProp here -->
>           <boolProp />
> <!-- Four more boolProp here -->
>         </HTTPSamplerProxy>
>         <hashTree>
>           <HeaderManager>
>             <collectionProp>
>               <elementProp>
>                 <stringProp />
>                 <stringProp />
>               </elementProp>
>              <!-- Four more elementProp with two stringProp each here -->
>             </collectionProp>
>           </HeaderManager>
>           <hashTree/> <!-- This empty hashTree is NOT optional -->
>           <RegexExtractor>
>             <stringProp />
> <!-- Six more stringProp here -->
>           </RegexExtractor>
>           <hashTree/> <!-- This empty hashTree at the end IS optional -->
>         </hashTree>
> Unaltered, this single request description is 107 lines and 7208 bytes.
> Note the <hashTree> after the </HTTPSamplerProxy> (and many -- but not all!
> -- other elements) is understood by JMeter as containing the _children_ of
> the <HTTPSamplerProxy>.  For elements with no children, it's still necessary
> that they be followed by an empty <hashTree/> if there are more elements at
> the same level of the tree.  (This is, I believe, a consequence of a
> TestPlan's internal representation as a ListedHashTree of ListedHashTrees.)
> As far as we've been able to determine, this format is entirely
> undocumented.
> The consequence of all this is it is EXTREMELY difficult to reliably operate
> on a JMX file with external tools, and much of it has been trial-and-error.
> Really, it's been a nightmare.  A DSL should have clean and clear semantics
> that prevent parsing ambiguity and speed development time.  Anything that
> does not is a wasted effort.
> So bearing all that in mind, I would strongly recommend this additional
> requirement: a new DSL MUST decouple the test plan format from
> implementation details.  A good example of how this is bad in JMX is all the
> attribute noise on any sampler-- the test plan shouldn't have to know about
> the guiclass, testclass, elementType, etc.  It's all obvious from the
> structure and the type of the node.
>> - the language it should be developed in. My personal preference would go
>> for Groovy but I am not an expert in DSLs.
> Hang on, why would you develop your DSL in a different language from what
> JMeter itself is actually written in?  This wold seem to  add an entire new
> toolchain to the build process.
>> - how to express what today we can do through JSR223 languages which might
>> be the most complex think to translate
> Is this really an issue?  This seems orthogonal to the goal of creating a
> language to describe _test plans_ themselves.  As long as this DSL has a way
> to express the JSR223 sampler, saving the actual code that goes in it should
> go without saying.
> Regards,
> Wyatt
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