Use Json as input to make REST call

Hello to all.
This is my first post here and about talend.
I'm  working on my first project in talend, and i need to call a REST webservice.
Input for call is JSON and response will be JSON too.
First of all what component should i use ? tREST, tRESTClient ?
secondly. i need to transform my RAW data (from HashMAP) to JSON, after that use it as input for a REST call.
- how do i make a JSON with values from hashmap ?
- how do i use JSON as input for ( tREST or tRESTClient ) ?
My work-flow.
1)read file --> 2) get needed data---> 3) convert data to Json ---> 4) make a REST call ----> 5) use response to send an email.

Re: Use Json as input to make REST call

From your description, the work flow should be:Input--> tXMLMAP(convert data to Jso)--> tRestClient(post) component calling a webservice to PUT data in json format.
Please take a look at component reference about:TalendHelpCenter:tRESTClient with related scenarios.
Best regards
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Re: Use Json as input to make REST call

what about invoking a rest webservice with talend ? how could we do such task ?