[Apiman-user] API policy response data handler
Balu S
sbalu27 at gmail.com
Fri Feb 3 06:38:00 EST 2017
sorry, I don't understand what you wrote.
I would like Apiman metrics to consider the HTTP response (>=400) as
failure/error (whatever that is appropriate) and indicate in below charts.
[image: Inline image 1]
On Fri, Feb 3, 2017 at 12:21 PM, Marc Savy <marc.savy at redhat.com> wrote:
> I think I understand what you're asking.
>
> IIRC:
>
> Error = an exception occurred within the gateway (e.g. could not connect
> to backend).
> Failure = a policy failure occurred.
>
>
> If you're wanting to look at http exception codes, just look at the
> 'responseCode' field in the ES Metrics.
>
> If you're wanting a "failed/not failed" determination then perhaps just
> execute `responseCode/100 == 2` in your analysis? Or is this not possible
> in your use-case?
>
> On 3 February 2017 at 10:45, Balu S <sbalu27 at gmail.com> wrote:
>
>> Its the default one ES.
>>
>> # ---------------------------------------------------------------------
>> # Elasticsearch Metrics Settings
>> # ---------------------------------------------------------------------
>>
>> apiman-gateway.metrics=io.apiman.gateway.engine.es.ESMetrics
>> apiman-gateway.metrics.client.type=jest
>> apiman-gateway.metrics.client.protocol=${apiman.es.protocol}
>> apiman-gateway.metrics.client.host=${apiman.es.host}
>> apiman-gateway.metrics.client.port=${apiman.es.port}
>> apiman-gateway.metrics.client.username=${apiman.es.username}
>> apiman-gateway.metrics.client.password=${apiman.es.password}
>> apiman-gateway.metrics.client.timeout=${apiman.es.timeout}
>> apiman-gateway.metrics.client.initialize=true
>>
>> On Fri, Feb 3, 2017 at 11:40 AM, Marc Savy <marc.savy at redhat.com> wrote:
>>
>>> Which metrics implementation are you using? The data you're talking
>>> about should be in there; if it's not then there's a problem.
>>>
>>>
>>> On 3 February 2017 at 09:50, Balu S <sbalu27 at gmail.com> wrote:
>>>
>>>> Thanks for your inputs.
>>>>
>>>> Yes, I mean HTTP error codes (non-200) that are returned to client. For
>>>> example, when a request is missing query parameters and the API responds
>>>> with a "Bad request" (400) along with error XML. Here the error code is set
>>>> at HTTP level only and Apiman metrics should consider it as bad response
>>>> (in my opinion). Neither I do not see the Apiman source (HttpApiConnection)
>>>> interpreting the HTTP response using the HTTP code. But with the custom
>>>> policy, If I check for non-200 code and handle as failure, then metrics
>>>> shows them as error.
>>>>
>>>> To clarify on my implementation with custom policy, I'm not trying to
>>>> change the HTTP error code based on the response, rather we are unpacking
>>>> the error response body and packing in different XML format as done by
>>>> Apiman. Is this not a valid scenario ? I think there could other scenarios
>>>> where one want to alter the response body. I agree there will be additional
>>>> cost to performance and memory, but can it be not done one demand basis
>>>> like how one can implement IDataPolicy to parse the response only if he
>>>> needs to.
>>>>
>>>> Thanks
>>>> Balu
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Thu, Feb 2, 2017 at 10:31 PM, Eric Wittmann <
>>>> eric.wittmann at redhat.com> wrote:
>>>>
>>>>> The bottom line here is that you cannot return a Policy Failure (or
>>>>> customize it) based on information in the response body. The response is
>>>>> streamed from the back-end to the client, and at the time streaming begins,
>>>>> the response code and HTTP headers have already been sent.
>>>>>
>>>>> It sounds to me like you're asking for a feature where you can parse
>>>>> the response body *before* the policy's "apply" method is invoked. We have
>>>>> such a feature for requests, but not for responses. I suspect core changes
>>>>> to apiman would be required to enable that. It seems like a reasonable
>>>>> request to me, as long as users of the feature understand the performance
>>>>> and memory requirements of enabling it.
>>>>>
>>>>> -Eric
>>>>>
>>>>>
>>>>> On Thu, Feb 2, 2017 at 1:03 PM, Marc Savy <marc.savy at redhat.com>
>>>>> wrote:
>>>>>
>>>>>> NB: This is distinct from the body you're setting which contains a
>>>>>> JSON/XML payload containing the error code. It's in the HTTP protocol
>>>>>> itself.
>>>>>>
>>>>>> On 2 February 2017 at 18:02, Marc Savy <marc.savy at redhat.com> wrote:
>>>>>>
>>>>>>> That sounds like metrics are going wrong, or perhaps you're
>>>>>>> misinterpreting it (adding Eric).
>>>>>>>
>>>>>>> When you say your API returns an error, does it still return an
>>>>>>> appropriate non-200 error code at the HTTP level? For instance, 500 or
>>>>>>> similar? That's very important.
>>>>>>>
>>>>>>> There's a difference between an error and a failure - have you
>>>>>>> checked both of those fields to see whether they contain the information
>>>>>>> you're expecting to see.
>>>>>>>
>>>>>>> Certainly in my experience we *do* collect the metrics you're
>>>>>>> talking about, unless I'm misunderstanding you.
>>>>>>>
>>>>>>> On 2 February 2017 at 17:40, Balu S <sbalu27 at gmail.com> wrote:
>>>>>>>
>>>>>>>> Hi Marc,
>>>>>>>>
>>>>>>>> I shall explain my use case. From our API call, we return error
>>>>>>>> response (in XML or JSON) for 401, 500 and so on. However, Apiman metrics
>>>>>>>> seems to just consider them as good response (it is, as Apiman received the
>>>>>>>> response back) and show as successful response. So I have made custom
>>>>>>>> policy to intercept the response to know if it is failure and trigger the
>>>>>>>> Policy Failure. This is fairly simple and straight forward as the response
>>>>>>>> code will just do the purpose. But I want also to add some additional
>>>>>>>> information about the failure to Policy Failure. This additional
>>>>>>>> information is in the original error response which will be lost once
>>>>>>>> doFailure() happens. And no we don't want to those additional information
>>>>>>>> in some HTTP headers to pass around. Hence I implemented responseHandler()
>>>>>>>> to handle the response buffer and like you pointed out, it seems to be too
>>>>>>>> late to meddle the response.
>>>>>>>>
>>>>>>>> So ideally, there are possible 2 solution
>>>>>>>>
>>>>>>>> - Apiman metrics can interpret the response as unsuccessful for
>>>>>>>> such error response from API call.
>>>>>>>> - Handle the response buffer data before the write() call to
>>>>>>>> response outputstream.
>>>>>>>>
>>>>>>>> Do you see any alternative solution?
>>>>>>>>
>>>>>>>> Thanks
>>>>>>>> Balu
>>>>>>>>
>>>>>>>> On Thu, Feb 2, 2017 at 6:15 PM, Marc Savy <marc.savy at redhat.com>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> Perhaps URLRewritingPolicy https://github.com/apiman/apim
>>>>>>>>> an/blob/master/gateway/engine/policies/src/main/java/io/apim
>>>>>>>>> an/gateway/engine/policies/URLRewritingPolicy.java be an
>>>>>>>>> informative place to start?
>>>>>>>>>
>>>>>>>>> - Apiman streams data, so the client may be receiving data already
>>>>>>>>> by the time you've determined you want to cancel (the connection is already
>>>>>>>>> established; headers have been sent) - it's often too late to gracefully
>>>>>>>>> cancel. You could try throwing an exception and seeing what happens (not
>>>>>>>>> recommended practice!).
>>>>>>>>>
>>>>>>>>> If that doesn't work, perhaps you can explain your use-case more
>>>>>>>>> clearly and explicitly so we can see what the alternatives are?
>>>>>>>>>
>>>>>>>>> - Policies are *static* instances, if you are assigning that
>>>>>>>>> buffer to the object then it's as if you were writing "static Buffer
>>>>>>>>> buffer" and different requests will all share that variable (and thus swap
>>>>>>>>> it out repeatedly!).
>>>>>>>>>
>>>>>>>>> Regards,
>>>>>>>>> Marc
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 2 February 2017 at 16:56, Balu S <sbalu27 at gmail.com> wrote:
>>>>>>>>>
>>>>>>>>>> Hello,
>>>>>>>>>> I'm trying to parse the response using responseDataHandler() in
>>>>>>>>>> the custom policy. In cases, if the response from API is of certain
>>>>>>>>>> content, I would like the Apiman to consider as failure. But I don't find a
>>>>>>>>>> way to throw policy failure from responseDataHandler(). And I cannot
>>>>>>>>>> achieve this in doApply() as the ApiResponse object does not have "content"
>>>>>>>>>> to parse.
>>>>>>>>>>
>>>>>>>>>> Also, what I found is write(chunk) in the AbstractStream is
>>>>>>>>>> called after doApply, so I cannot set any attributes in it to fetch it in
>>>>>>>>>> doApply() and trigger doFailure().
>>>>>>>>>>
>>>>>>>>>> For example, in below call, how to throw as policy failure after
>>>>>>>>>> parsing the contents ? Or how can I access response content even before
>>>>>>>>>> write() method.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> *URLRewritingPolicy.java*
>>>>>>>>>>
>>>>>>>>>> @Override
>>>>>>>>>> protected IReadWriteStream<ApiResponse>
>>>>>>>>>> responseDataHandler(ApiResponse response,
>>>>>>>>>> IPolicyContext context, URLRewritingConfig
>>>>>>>>>> policyConfiguration) {
>>>>>>>>>> if (policyConfiguration.isProcessResponseBody()) {
>>>>>>>>>> return new URLRewritingStream(context.get
>>>>>>>>>> Component(IBufferFactoryComponent.class), response,
>>>>>>>>>> policyConfiguration.getFromRegex(),
>>>>>>>>>> policyConfiguration.getToReplacement());
>>>>>>>>>> } else {
>>>>>>>>>> return null;
>>>>>>>>>> }
>>>>>>>>>> }
>>>>>>>>>>
>>>>>>>>>> *URLRewritingStream.java*
>>>>>>>>>>
>>>>>>>>>> /**
>>>>>>>>>> * @see io.apiman.gateway.engine.io.AbstractStream#write(io.
>>>>>>>>>> apiman.gateway.engine.io.IApimanBuffer)
>>>>>>>>>> */
>>>>>>>>>> @Override
>>>>>>>>>> public void write(IApimanBuffer chunk) {
>>>>>>>>>> if (buffer == null) {
>>>>>>>>>> buffer = bufferFactory.cloneBuffer(chunk);
>>>>>>>>>> } else {
>>>>>>>>>> buffer.append(chunk);
>>>>>>>>>> }
>>>>>>>>>> atEnd = false;
>>>>>>>>>> processBuffer();
>>>>>>>>>> }
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Best regards
>>>>>>>>>> Balu
>>>>>>>>>>
>>>>>>>>>> _______________________________________________
>>>>>>>>>> Apiman-user mailing list
>>>>>>>>>> Apiman-user at lists.jboss.org
>>>>>>>>>> https://lists.jboss.org/mailman/listinfo/apiman-user
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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