[Apiman-user] Is it possible blocking request after request body parsing?

[Eric Wittmann]

Yes that is the UI option I was referring to.

If the request payload is being parsed without that option being set, then
there is a bug in the Apiman gateway.  I will write up a bug report for
that so that @marcsavy can have a look. :)

-Eric


On Thu, Apr 26, 2018 at 4:36 AM, 林 柏廷 <btlin1025 at hotmail.com> wrote:

> Dear Eric
>
> Thanks for your helpful information.
> I can get request body with IPolicyContext object.
> Besides, you also mentioned *enable this on a per-API basis in the apiman
> UI.*
> Is It "Enable stateful request payload insepction" in API implementation
> tab?
> I'm wondering because I didn't enable this option but can still get the
> request body in doApply() with IPolicyContext.
> What is the difference if I enable this option?
> Thanks
>
> Regards
>
> ------------------------------
> *寄件者:* Eric Wittmann <eric.wittmann at redhat.com>
> *寄件日期:* 2018年4月25日 下午 08:15
> *收件者:* 林 柏廷
> *副本:* apiman-user at lists.jboss.org
> *主旨:* Re: [Apiman-user] Is it possible blocking request after request
> body parsing?
>
> Yes there is a feature where apiman will parse the request BEFORE applying
> the policies.  This will make the HTTP request body available to all
> policies in the chain, should they need them.
>
> You can enable this on a per-API basis in the apiman UI.
>
> When this feature is enabled, your custom policy can access the request
> body as an object found in the IPolicyContext object.  For example:
>
> Object payload = context.getAttribute("apiman.request-payload");
>
> The type of thing that you get depends on the API's endpoint type.  The
> endpoint type might be JSON, XML, or SOAP.  I think it might be possible to
> have some other kind of endpoint type, but those three are handled by the
> request body parser feature.
>
> Here is what you'll get as that payload object, depending on endpoint type:
>
> JSON - Java Map object as a result of parsing the JSON data using Jackson
> XML - org.w3c.dom.Document
> Soap - javax.xml.soap.SOAPEnvelope
> Anything Else - byte[]
>
> So for example, if your endpoint type is XML, then you could do this in
> your policy implementation (in the doApply() method):
>
> org.w3c.dom.Document requestBody = (org.w3c.dom.Document) context.get
> tAttribute("apiman.request-payload");
>
> And then you could make some decision using the request data and e.g. call
> doFailure().
>
> Also note - you can *change* the request body at this point as well.  For
> example you could apply a XML Transformation to the w3c Document, resulting
> in a new w3c Document object, which you could store in the Policy Context
> (at the same key, obviously).  That new document would then get serialized
> and sent as the request body to the backing API impl.  There may be some
> Content-Length issues if you do that, I can't remember...
>
> -Eric
>
>
> On Wed, Apr 25, 2018 at 1:29 AM, 林 柏廷 <btlin1025 at hotmail.com> wrote:
>
> Hi all,
> I would like to customize a policy, which parses the request body and
> blocks the request in case.
> in http://www.apiman.io/latest/developer-guide.html 4.2.1.2 IData policy,
> it describes:
> The request or response body will not begin streaming before the
> corresponding doApply has been called, however, it is still possible to
> interrupt the conversation during the streaming phase by signalling
> doFailure or doError.
> When I trace the transformation-policy source code, doApply() executes
> before getRequestDataHandler() which matches the description.
> In doApply() I can blocks the request via chain.doFailure() however I have
> no idea how to interrupt/block request in getRequestDataHandler().
> Besides, I found following mail group which is similar to my question.
> Eric also points it's possible to parse the body before apply in request:
>
> *On Thu, Feb 2, 2017 at 10:31 PM, Eric Wittmann <*
> *eric.wittmann at redhat.com <http://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*
>
> Thanks for any comments in advance.
> Kind Regards
> BT
>
>
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