Passing a response value from GRPC response to a REST API in Scala Gatling

Question

hope you are doing good today

Cut to the chase that I keep on asking fun-to-dumb questions, this time before I raise something, I look into it very closely before ask to avoid tiredness. Ngl this is a fun-with-pain experience for me

My new update code block

val speaker = scenario("BasicSimu")
  .exec(
    fromClientSide
      .start(thePayload)
      .header(Authorization)(s"Bearer $TokenKey")
      .extract(.pk.some)(_ saveAs "theString")
      .sessionCombiner(SessionCombiner.pick("theString"))
      .endCheck(statusCode is Status.Code.OK)
  )
  .exec{
      session => 
        val responseString = session.attributes.get("theString").toString().slice(21,28)
        val newKeyVar = session.set("myKey",responseString)
      newKeyVar
  }
  .exec(
        http("Complete_Pairing") //the little body I made here
          .post(s"url")
          .header("Content-Type","application/json")
          .body(StringBody(s"""{
                      "pk": {"pairingKey": "#{newKeyVar}"}
                      }"""))
          .check(status.is(200))
  )
  .exec(fromClientSide.reconciliate(waitFor = StreamEnd))

As this code block introduce, I need the pairingKey to get it out, so I cast it to a String, then slice it, holy moly the key returned.

Continue to investigate, I have myself answered some questions, beside that there are some that I can't self-answer, so I bring up here.

1/ Needlessly to say the pairingKey (aka responseString keeping it, inside a session) has its purpose, and it is used to pass into body for a POST REST calling, is it possible to get the responseString out? With the code block above aspect, responseString not found (understandable, it's inside a session bruh), In example code you can cast it directly by using session.attributes.get to get the value, but when plug to REST, I think session.attributes.get cannot be casted directly.

Brief: I see the session.set, I will see more on this

2/ Following the first question, I have in mind two ways to approach, one is to save data down to csv and other one, calls the value directly. Should I just go call it directly to avoid slow processing ?

3/ Yesterday I did ask a way to keep the stream alive to view result, but now that I need the stream to run until it get a response 0 OK, it will pop up immediately when the REST API is made, tried with reconciliate(waitFor = NextMessage) but it seems the stream cancelled immediately, not sure if I cast it right.

4/ Out of topic, just a concern, that can I push my demo (if somehow I manage to achieve this with your support), to your Github ?

Answer 1

So days of investigating, I have completed a full code for a ServerStream combining with REST, this is a simple made, since there are many ways to interact with data, I'm just too noobie to improve it, for now.

val speaker = scenario("BasicSimulation")
  .exec(
    fromClientSide //read my prev questions to know my configuration
      .start(thePayload)
      .header(Authorization)(s"Bearer $TokenKey") 
      .extract(."yourParam".some)(_ saveAs "theString")
      .sessionCombiner(SessionCombiner.pick("theString"))
      .endCheck(statusCode is Status.Code.OK)
  ) 
  .exec(fromClientSide.reconciliate(waitFor = NextMessage)) //tell the stream to wait
  .exec{
    session => 
        //Extract will return a Some type data, cast it to String type, then slice it to get the key
        val responseString = session.attributes.get("theString").toString().slice(your, position)

        // Print out to verify see the value of the key, comment it later if no use
        println(s"the pairingKey is: ${responseString}")

        // Init a new session to get the value
        val newKeyVar = session.set("myKey", responseString)
    newKeyVar
  }

  .exec(  
      http("Complete_Pairing")
        .post("your url")
        
        //sample header
        .header("Authorization", s"$tokenREST")
        .header("Content-Type","application/json")
        
        //sample Body
        .body(StringBody("""{"pk": {"pairingKey": "#{myKey}"}"}"""))
        .check(status.is(200))
        .check(bodyString.saveAs("responseBody"))
        .check(jsonPath("$.session.id").saveAs("sessionID"))
        .check(jsonPath("$.at.token").saveAs("unpairToken"))
  )
  //uncomment this block to check your response
  // .exec{
  //     session => 
  //       val responseBody = session("responseBody").as[String]
  //       println(s"Response Body: $responseBody")
  //     session
  // }

Some of my comment could be false understanding, mostly you have to build on your ownm so some variable/object can be abstract, so if something needs to be fixed, please let me know so that I can fix immediately