[Apiman-user] API policy response data handler
Balu S
sbalu27 at gmail.com
Fri Feb 3 05:45:17 EST 2017
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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