[jax-rs-spec users] Re: _at_Path with regular expression overrides other @Path's with the same URI

From: Sergey Beryozkin <>
Date: Thu, 15 Oct 2015 14:24:11 +0100

On 15/10/15 14:22, Sergey Beryozkin wrote:
> Hi Marek
> OK, RestEasy is not compliant. Oh, and CXF too :-).
That depends on the what your check on the TCK for minor versions
reveals :-)

Cheers, Sergey

> However IMHO it does make sense sometimes to step back a bit and
> evaluate that may be it is not a 'by design' spec feature - this is
> the impression I got from Santiago's comment requesting opening a JIRA
> issue. I agree that the ensuring the portability is critical, though I
> agree with Bill's comment re the usability being as equally important...
> I'll open a JIRA, assign to Santiago and then both of you can decide
> what to do :-)
> Cheers, Sergey
> On 15/10/15 13:11, Marek Potociar wrote:
>> Hi Sergey,
>> Well, the discussion on the Jersey thread clearly shows how confusing
>> it is if the implementations are not 100% compliant with the spec.
>> You either are compliant or you are not. There are no shades of gray
>> when it comes to official spec compliance. If you pass TCK, you are
>> compliant, if you don’t you are not. If there is a hole in TCK
>> coverage, it may get fixed later and then you would need to pass the
>> fixed TCK to be compliant.
>> The standard specifications are here to ensure application
>> portability for users. From the user perspective a pure JAX-RS code
>> must behave the same way on ANY implementation that claims to be
>> JAX-RS compliant.
>> Marek
>>> On 15 Oct 2015, at 01:03, Sergey Beryozkin <>
>>> wrote:
>>> Hi Markus
>>> I'd like to refer to the other thread where you agreed we should not
>>> rush it.
>>> Yes, as it currently stands - RestEasy and CXF are not compliant in
>>> this specific case.
>>> However IMHO we should strive really hard not to treat such cases as
>>> this is how it should and that is it.
>>> I think it is more of a spec text being non-intentionally too strict
>>> in this case - lets give it a chance - if Santiago can find an
>>> opportunity to 'fix' it then we will all win, if not then at least
>>> we gave it another try
>>> Cheers, Sergey
>>> On 14/10/15 21:41, Markus KARG wrote:
>>>> Sergey,
>>>> I understand your arguments, but for users (and for TCK) compliance
>>>> is a true/false question. As an ISV I need to rely on the fact that
>>>> matching works exactly the same on all implementations (at least as
>>>> long the spec does not provide a means for an application to
>>>> provide its own matching algorithm).
>>>> So what do we tell people now? They wait for an answer. Are
>>>> CXF/RestEasy definitively non-compliant or not?
>>>> -Markus
>>>> -----Original Message-----
>>>> From: Sergey Beryozkin []
>>>> Sent: Montag, 12. Oktober 2015 22:33
>>>> To:
>>>> Subject: Re: @Path with regular expression overrides other @Path's
>>>> with the same URI
>>>> Hi Santiago
>>>> I was thinking on the way home, I thought the sentence where the
>>>> 'M' set is built from Rmatch = R(Td) is a bit strict.
>>>> I recall the explicit regular expressions were added at the last
>>>> moment in 1.0, the current text covers a situation with same verbs
>>>> OK (in that Jersey issue I thought there were two GETs where I'd
>>>> indeed expect the method with an explicit reg expression win)...
>>>> Rmatch = R(Td) condition blocks a GET method from being included in
>>>> M (referring to that example).
>>>> I suspect replacing a '=' symbol with another one implying Rmatch
>>>> is equal or equivalent to R(Td).
>>>> I suspect I might've got confused with my analysis above but I open
>>>> an issue
>>>> Markus, I'm not sure the fact CXF/Reasteasy would not select DELETE
>>>> makes either implementation broken :-).
>>>> My opinion the spec text is far from being perfect in this specific
>>>> case which I agree makes CXF/RestEasy is not compliant here but
>>>> perhaps in this case the spec text can be optimized before a new
>>>> TCK test is added :-).
>>>> Thanks, Sergey
>>>> On 12/10/15 19:22, Santiago Pericasgeertsen wrote:
>>>>>> On Oct 12, 2015, at 1:03 PM, Markus KARG <>
>>>>>> wrote:
>>>>>> Sergey,
>>>>>> so what is the conclusion now? CXF is broken and you will fix it?
>>>>> Let’s file it as an issue and review it later. I had a quick
>>>>> look at the algorithm and, frankly, it is not as clear as I hoped
>>>>> so but I don’t have the cycles to look at it deeper at this point.
>>>>> — Santiago
>>>>>> -----Original Message-----
>>>>>> From: Sergey Beryozkin []
>>>>>> Sent: Montag, 12. Oktober 2015 17:26
>>>>>> To:
>>>>>> Subject: Re: @Path with regular expression overrides other @Path's
>>>>>> with the same URI
>>>>>> Hi Santiago
>>>>>> That long discussion we last had, that was related to a case where a
>>>>>> matching subresource locator was discarded, even though it was
>>>>>> having
>>>>>> a matching method, as opposed to the current resource class.
>>>>>> It still 'hurts' whenever I think about it.
>>>>>> But in this case it is different, no backtracking of any sort is
>>>>>> even
>>>>>> needed here - it is so simple...
>>>>>> So we are at "Sort E using the number of literal
>>>>>> characters in each member as the primary key (descending order), the
>>>>>> number of capturing groups as a secondary key (descending order),
>>>>>> the
>>>>>> number of capturing groups with non-default regular expressions
>>>>>> (i.e.
>>>>>> not
>>>>>> '([^/]+?)') as the tertiary key
>>>>>> (descending order)..."
>>>>>> Then yeah, DELETE is supposed to be selected. This is so sad. The
>>>>>> only consolation, regular expressions are not that popular...
>>>>>> Sergey
>>>>>> On 12/10/15 14:31, Santiago Pericasgeertsen wrote:
>>>>>>> All,
>>>>>>> First, obviously I agree the result is counter-intuitive.
>>>>>>> Second,
>>>>>>> we
>>>>>> have had this this discussion many in the times in the past ;), and
>>>>>> basically the same algorithm since JAX-RS 1.0 AFAIK. Third, the
>>>>>> algorithm does not backtrack or look ahead, and thus makes a
>>>>>> decision
>>>>>> first on Path and then on method resulting in the observed behavior
>>>>>> -because it discarded potential matches too soon.
>>>>>>> If an implementation behaves differently, it is because it is
>>>>>> implementing a different algorithm from the one in the spec. Ideally
>>>>>> we should change the algorithm, but unfortunately it is not a
>>>>>> backward compatible change.
>>>>>>> - Santiago
>>>>>>>> On Oct 12, 2015, at 9:08 AM, Sergey Beryozkin
>>>>>>>> <>
>>>>>> wrote:
>>>>>>>> Oh, that is actually completely broken, I agree, I thought there
>>>>>>>> were two
>>>>>> GET methods there, my fault.
>>>>>>>> I honestly can not see how that can be resolved as works as
>>>>>>>> expected...
>>>>>>>> Sergey
>>>>>>>> On 12/10/15 14:00, Bill Burke wrote:
>>>>>>>>> If this is true, then the matching algorithm is showing yet
>>>>>>>>> again,
>>>>>>>>> how
>>>>>> effed up it is. The @Get method in the example should always
>>>>>> resolve. It makes sense intuitively. In Resteasy if the @Delete
>>>>>> path
>>>>>> resolved first, but the methods didn't match, we would
>>>>>> "backtrack" and try the get method.
>>>>>>>>> On 10/11/2015 12:00 PM, Sergey Beryozkin wrote:
>>>>>>>>>> Jersey is correct in that example - a template var with a regex
>>>>>>>>>> wins over a basic template var.
>>>>>>>>>> The spec clearly states that an expression with more literal
>>>>>>>>>> chars
>>>>>> wins.
>>>>>>>>>> So I guess a regex expression can only win if, besides the
>>>>>>>>>> rex-ex
>>>>>>>>>> expression itself, a given path has more literal chars, say,
>>>>>>>>>> abc[d|e] would win over abc - I think this can only happen when
>>>>>>>>>> choosing between multiple matching root resources.
>>>>>>>>>> Or it can win in that Jersey JIRA issue - a number of literal
>>>>>>>>>> chars beyond the regex is equal but the regex method wins
>>>>>>>>>> because
>>>>>>>>>> a template var is more specific. I'll double check with CXF - I
>>>>>>>>>> doubt it works
>>>>>> diff
>>>>>>>>>> in CXF
>>>>>>>>>> Sergey
>>>>>>>>>> On 11/10/15 08:28, Markus KARG wrote:
>>>>>>>>>>> Experts,
>>>>>>>>>>> in a discussion on the Jersey user group someone claimed that
>>>>>>>>>>> the behaviour of Jersey is different from CXF and RestEasy. As
>>>>>>>>>>> that would imply both, an inaccuracy of the TCK (it does not
>>>>>>>>>>> detect the
>>>>>>>>>>> deviation) and a violation of the specification in CXF and
>>>>>>>>>>> RestEasy (as Jersey is the RI, hence axiomatically cannot be
>>>>>>>>>>> wrong), we should quickly clarify the truth in that claim.
>>>>>>>>>>> The case is recorded in Jersey's issue tracker including source
>>>>>>>>>>> code
>>>>>>>>>>> ( and is simple to
>>>>>>>>>>> explain:
>>>>>>>>>>> *Given a resource has two methods, annotated as **_at_GET
>>>>>>>>>>> @Path(//<PathParam>/) and **_at_DELETE @Path(//<RegEx>/)*
>>>>>>>>>>> *When a client invokes **GET <RootURI>//<PathParam>/ upon that
>>>>>> resource*
>>>>>>>>>>> *Then the result is **405 Method Not Allowed*
>>>>>>>>>>> While this looks pretty odd to the average Joe (as there is a
>>>>>>>>>>> perfect match of GET and /<PathParam>/), it was claimed that
>>>>>>>>>>> this is _compliant_ to the specification (since regex have
>>>>>>>>>>> higher priority than literals, and methods are matched after
>>>>>>>>>>> URIs).
>>>>>>>>>>> It was reported that CXF and RestEasy return 200 OK instead,
>>>>>>>>>>> while the RI does return 405 Method Not Allowed.
>>>>>>>>>>> Certainly an application MUST return the same status code on
>>>>>>>>>>> ANY
>>>>>>>>>>> JAX-RS compliant implementations, so we should clarify ASAP the
>>>>>>>>>>> following questions:
>>>>>>>>>>> (1) @SpecLeads: Is the use case described above (regex beats
>>>>>>>>>>> literals) really compliant to the JAX-RS specification, and how
>>>>>>>>>>> to explain /to the average Joe/ the reasonability of ignoring
>>>>>>>>>>> the apparently perfect match?
>>>>>>>>>>> (2) @SpecLeads: Is there a bug in the TCK so it does not detect
>>>>>>>>>>> the deviation of CXF and RestEasy?
>>>>>>>>>>> (3) @Vendors: Can you please check your implementations whether
>>>>>>>>>>> they really violate the spec? Do you have plans to fix it?
>>>>>>>>>>> I think we all have a vital interest in clarifying it, as a
>>>>>>>>>>> standard makes only sense when it is reasonable and commonly
>>>>>>>>>>> accepted, so I would be glad if you could answer the above
>>>>>>>>>>> points rather soon. :-)
>>>>>>>>>>> Thanks
>>>>>>>>>>> -Markus