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This tip documents how to:

1. Create a low-code module to consume a REST API.
2. Call the low-code module from an RPG program, by using the PJSCALL program.

Create a low-code module to consume a REST API

• Navigate to the workspace "pjstips".
• Click New/Module File.

• Click Edit/Source, to bring up the Source view.

• Clear the current default code, and enter the code below.

• 
  

  Code Block
  language js title pjstips_03_1.module.json
  { "routines": [ { "name": "routine1", "inputs": [ { "type": "decimal", "ibmiLength": 4, "name": "custno", "ibmiDecimals": 0 } ], "outputs": [ { "type": "string", "ibmiLength": 30, "name": "name" } ], "steps": [ { "text": "Consume REST service", "answers": { "plugin": "Custom:web-service", "uri": "http://localhost:8081/run/pjstips/pjstips_02_3", "method": "POST", "headers": "", "body": "{\n \"custno\": input[\"custno\"]\n}", "json": true, "auth": "", "capture_response": true, "capture_on_error": false, "capture_as": "Value", "specific_property": "", "destination": "Work variable", "work_variable": "myres" } }, { "text": "Set Module output", "answers": { "plugin": "Program Data:set-module-output", "module-output-values": { "name": "myres[\"name\"]" } } } ] } ] }

  
  

• Click Edit/Design, to bring up the Design view.
• If needed, in the "Consume REST service" step, change the Endpoint URL to point to the correct host/port.
• Click Home/Save As, and save as pjstips_03_1.module.json.
• You've created a low-code module, as shown below, with a routine named "routine1" that:
  
  • Takes an input parameter of "custno".
  • Uses plugin "Consume REST service" to issue a POST request to URL http://localhost:8081/run/pjstips/pjstips_02_3 (created in a previous example).
  • The input "custno" is specified in the "body" of the POST request.
  • The returned JSON object from the REST web service is saved in a work variable named "myres".
  • The value of myres["name"] is used to set the output value output["name"].
• 

Call the low-code module from an RPG program

• You can call this low-module from another low-code module, from another "regular" (i.e. NOT low-code) PJS module, or from an RPG program. To call it from an RPG program, use the code generated in the panel "IBM i Call Interface" panel.

• Below is an example, there where the input custno is set to 1234 to pass to the low-code module, which calls the REST service to get the customer name, which is then returned to the RPG program, which is then displayed on the screen.

**free

  Dcl-PR PJSCALL ExtPgm;
    ParmType        Char(30)          Const;
    ModuleID        VarUCS2(500)      Const;
    RoutineName     VarUCS2(70)       Const;
    InputParms      Char(16773104)    Const Options(*Varsize:*Omit:*NoPass);
    InputParmSize   Int(10)           Const Options(*Omit:*NoPass);
    OutputParms     Char(16773104)    Options(*Varsize:*Omit:*NoPass);
    OutputParmSize  Int(10)           Const Options(*Omit:*NoPass);
  End-PR;

  Dcl-DS InputDS Qualified Inz;
    custno  Zoned(4: 0);
  End-DS;

  Dcl-DS OutputDS Qualified Inz;
    name  VarChar(30);
  End-DS;

  InputDS.custno = 1234;			// pass input to the low-code module in "InputDS"

  Monitor;

    PJSCALL('*MODULE'
      : 'pjstips:pjstips_03_1.module.json'
      : 'routine1'
      : InputDS
      : %Size(InputDS)
      : OutputDS
      : %Size(OutputDS)
    );

  On-Error;


  EndMon;

  dsply  OutputDS.name;				// output from the low-code module in "OutputDS"		
  *inlr = *on;
  return;

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