[Apiman-user] API policy response data handler

[Marc Savy]

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/
>> apiman/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.g
>>> ateway.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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