Hi Lahiru,
Thanks for the clarification. It cleared my doubt.
Amitha
On Sep 27 2018, at 8:02 am, Lahiru Madushanka <lahirum...@wso2.com> wrote:
>
> Hi Amith,
>
> Explanation of how json-eval() works.
>
> We have two kinds of path expressions in synapse, synapseJsonPath and
> synapseXPath
> Following method is where we evaluate the json-eval() expressions
>
> public String stringValueOf(MessageContext synCtx) {
> org.apache.axis2.context.MessageContext amc = ((Axis2MessageContext)
> synCtx).getAxis2MessageContext();
> InputStream stream;
> if (!JsonUtil.hasAJsonPayload(amc) || "true".equals(enableStreamingJsonPath))
> {
> try {
> if (null == amc.getEnvelope().getBody().getFirstElement()) {
> // Get message from PT Pipe.
> stream = getMessageInputStreamPT(amc);
> if (stream == null) {
> stream = JsonUtil.getJsonPayload(amc);
> } else {
> JsonUtil.getNewJsonPayload(amc, stream, true, true);
> }
> } else {
> // Message Already built.
> stream = JsonUtil.toJsonStream(amc.getEnvelope().getBody().getFirstElement());
> }
> if(stream != null) {
> return stringValueOf(stream);
> }else{
> log.warn("Json Payload is empty.");
> return "";
> }
> } catch (IOException e) {
> handleException("Could not find JSON Stream in PassThrough Pipe during JSON
> path evaluation.", e);
> }
> } else {
> stream = JsonUtil.getJsonPayload(amc);
> return stringValueOf(stream);
> }
> return "";
> }
>
>
> In all the branches we use stringValueOf(stream) method to evaluate the
> jsonPath expressions against an input-stream.
> Where we take the stream is dependent on certain conditions as in the above
> implementation.
>
> If message already build we convert message body to a JSON stream in
> > stream =
> > JsonUtil.toJsonStream(amc.getEnvelope().getBody().getFirstElement());
> >
> >
>
> If message is not already built we take the stream from passthrough Pipe
>
>
> > Pipe pipe= (Pipe)
> > context.getProperty(PassThroughConstants.PASS_THROUGH_PIPE);
> >
>
> In the final else condition we take the stream from a property in axis2
> message context
>
>
> > Object o =
> > messageContext.getProperty(ORG_APACHE_SYNAPSE_COMMONS_JSON_JSON_INPUT_STREAM);
> >
>
>
> You can find all implementation details in [1]
>
> [1] https://github.com/wso2/wso2-synapse
>
> Thanks,
> Lahiru
>
>
>
>
>
>
>
> On Wed, Sep 26, 2018 at 7:31 PM Nuwan Dias <nuw...@wso2.com
> (mailto:nuw...@wso2.com)> wrote:
> > Adding Isuru and Shafreen.
> >
> > The mediation engine (EI/API Gateway) supports transforming or changing
> > messages from various protocols to various other protocols. Such as from
> > XML to JSON, from Text to XML, from form-url to JSON, likewise. To support
> > these various types of transformations, upon receiving a message the engine
> > would first convert it into a common base, and then convert it to the
> > requested base, likewise. Without doing which, the combinations of these
> > transformations would be endless. In the case of EI/API Gateway, this
> > common base is XML. So every message, if you need to process it, is first
> > converted to XML and then all changes or transformation are done on the
> > particular XML message and then converted to whatever the requested format
> > is. So as far as I know you can't work with the message on plain JSON
> > format only. However, I've added two of my colleagues who have a better
> > idea about this than me to see if this is possible.
> >
> > Thanks,
> > NuwanD.
> >
> >
> > On Wed, Sep 26, 2018 at 2:11 PM Amitha Dissanayake <ami...@yaalalabs.com
> > (mailto:ami...@yaalalabs.com)> wrote:
> > > Hi Nuwan,
> > >
> > > Thanks a lot for the prompt response. That document helped. However, my
> > > original question still remains unresolved to me.
> > > More specifically, when using the class mediator, I used the property
> > > mediator and received the JSON string to the class. But I still have to
> > > convert to XML and load it to the axis2 context message envelope (i.e.
> > > SOAP).
> > > <property name="messageType" value="application/json" scope="axis2"/>
> > > <property name="JSON-Payload" expression="json-eval($.)"/>
> > >
> > >
> > >
> > > I couldn't find how this json-eval() function evaluates the JSON payload
> > > (Whether it's accessing a JSON representation or an XML representation).
> > > How can I do this without converting the JSON to XML (without converting
> > > it to XML and attaching to axis2 message)?
> > > How is JSON represented in the EI / API Manager by default (XML or JSON)?
> > > I understand that conversions and manipulations are possible either way.
> > > Can the the EI / API Manager keep the JSON payload not converted
> > > end-to-end (i.e. from the point of backend REST API sending the response
> > > with a JSON payload till the requester receiving it?
> > > I'm evaluating API Manager, while hoping to apply it to a latency and
> > > performance critical application. That is why I'm trying to understand
> > > how it works in the EI.
> > > Thanks.
> > > Regards,
> > > Amitha
> > >
> > > On Sep 26 2018, at 2:12 pm, Nuwan Dias <nuw...@wso2.com
> > > (mailto:nuw...@wso2.com)> wrote:
> > > >
> > > > Hi Amitha,
> > > >
> > > > Maybe this document [1] would help you understand how to deal with JSON
> > > > payloads better.
> > > >
> > > > [1] -
> > > > https://docs.wso2.com/display/EI630/Working+with+JSON+Message+Payloads
> > > >
> > > > Thanks,
> > > > NuwanD.
> > > >
> > > >
> > > >
> > > > On Wed, Sep 26, 2018 at 10:01 AM Amitha Dissanayake
> > > > <ami...@yaalalabs.com (mailto:ami...@yaalalabs.com)> wrote:
> > > > > Hi,
> > > > >
> > > > > I'm a developer who's exploring API Manager. When I was attempting to
> > > > > retrieve the JSON payload form a Context Message during mediation
> > > > > (out sequence), I observed that the payload it attached in a SOAP
> > > > > Envelope inside the Axis2 Context Message. However, I'm receiving the
> > > > > response from a REST endpoint.
> > > > > In that case I had to convert the SOAP Evelope XML to JSON, then
> > > > > modify the changes and again convert it to XML and attach to Axis2
> > > > > Context Message. In that operation, 4 conversions happen. That is,
> > > > > Between the endpoint and mediation point. JSON to XML
> > > > >
> > > > > During mediation, I convert XML to JSON and do the operation,
> > > > >
> > > > > I again convert the JSON to XML and attach to the axis2 message.
> > > > >
> > > > > Postman receives a JSON; means XML has again been converted inside
> > > > > the API Manager.
> > > > >
> > > > > When I ran the mediation on debug mode, I observed that the content
> > > > > is received as SOAPAction to the mediation point.
> > > > > I feel that this adds an unnecessary latency overhead or I am doing
> > > > > something wrong in the process. Is there a way to overcome this
> > > > > issue/ directly access the JSON payload or what is the correct way to
> > > > > access the JSON payload without too many conversions?
> > > > > Thanks in Advance.
> > > > > Regards,
> > > > > Amitha Dissanayake
> > > > > Senior Software Engineer
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > Yaala Labs
> > > > >
> > > > > 14 Sir Baron Jayathilake Mawatha
> > > > >
> > > > > Colombo 1, Sri Lanka
> > > > >
> > > > > m: + 94 77 548 1350
> > > > >
> > > > > e: ami...@yaalalabs.com (mailto:ami...@yaalalabs.com)
> > > > >
> > > > >
> > > > >
> > > > > www.yaalalabs.com (http://www.yaalalabs.com/)
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > _______________________________________________
> > > > > Dev mailing list
> > > > > Dev@wso2.org (mailto:Dev@wso2.org)
> > > > > http://wso2.org/cgi-bin/mailman/listinfo/dev
> > > >
> > > >
> > > >
> > > >
> > > > --
> > > > Nuwan Dias | Director | WSO2 Inc.
> > > >
> > > > (m) +94 777 775 729 | (e) nuw...@wso2.com (mailto:nuw...@wso2.com)
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > >
> >
> >
> >
> >
> > --
> > Nuwan Dias | Director | WSO2 Inc.
> >
> > (m) +94 777 775 729 | (e) nuw...@wso2.com (mailto:nuw...@wso2.com)
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > _______________________________________________
> > Dev mailing list
> > Dev@wso2.org (mailto:Dev@wso2.org)
> > http://wso2.org/cgi-bin/mailman/listinfo/dev
>
>
>
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