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• Populating FHIR Response Messages

  Populating FHIR Response Messages

  Using an instance of InterSystems IRIS® for Health configured as a FHIR Facade, you will complete a production that accepts HL7® FHIR® requests, retrieves the requested data from an InterSystems® database, and sends this data back to the requesting system in the FHIR format.

  FHIR requests and responses are an integral part of the process when using InterSystems IRIS for Health or HealthShare® Health Connect to create a FHIR interoperability solution. In the case of a FHIR Facade, external systems request data in the FHIR format using a FHIR request. After gathering the data and transforming it into the FHIR format, you must then populate a FHIR response message to send the data back to the requesting system.

  In this exercise, you will take patient data that has been transformed into the FHIR format and populate a FHIR response message with this data. Then, you will request the patient data using a REST client to confirm that the response message was populated correctly.

  • Before starting this exercise, watch the FHIR Facade Architecture Overview (video, 4m) to get an introduction.
• Start the Exercise

  Start the Exercise
  •  You must be logged in to launch an InterSystems IRIS instance.

    • Log in with your existing account.
    • Don't have an InterSystems account? Create a new account.
  • In the lab you launched, the InterSystems IRIS for Health instance has a business process called FHIRInteroperability.BP.GetPatient in the FHIRINTGAD namespace. This business process is already configured to do the following:

    • Receive a FHIR request from an external system that needs patient data in the FHIR format.
    • Determine if the requested patient exists.
    • Retrieve the patient information from the internal database.
    • Transform this data into the FHIR format.

    Once the data is in the FHIR format, you must populate the FHIR response message. To do so, you will add code to the business process to populate a FHIR response message with the transformed patient data.

  • Write code to populate a FHIR response message
    

    1. Open the Management Portal by using the link on the lab desktop, and use the credentials tech and demo.
    2. Verify you are in the FHIRINTGAD namespace, clicking Switch if necessary.
    3. Navigate to Interoperability > Build> Business Processes and open the FHIRInteroperability.BP.GetPatient business process.
       Note the following classes:
       • Request class: HS.FHIRServer.Interop.Request
       • Response class: HS.FHIRServer.Interop.Response
    4. Delete the connector between the Patient Info to Resource activity and the join activity.
    5. Below the Patient Info to Resource activity, add a new assign activity with the following settings:
       1. Name: JSON from Resource
       2. Action: set
       3. Property: context.JSONPayloadStream
       4. Value: context.PatientResource.ToJSON()
       This activity takes the FHIR Resource produced by the data transformation, converts it into JSON, and saves it to a stream.
    6. Next, you must create a quickstream from this stream and populate the FHIR response message. Add a new code activity with the following settings, making sure each line of code begins with a space.
       1. Name: Populate FHIR Response
       2. Code:
          Begin code:

           set qs=##class(HS.SDA3.QuickStream).%New()
           set response.QuickStreamId = qs.%Id()
           set copyStatus = qs.CopyFrom(context.JSONPayloadStream)
           set response.Response.ResponseFormatCode="JSON"
           set response.Response.Status=200
           set response.ContentType="application/fhir+json"
          

          End code.
       After this code creates a new quickstream and copies the FHIR data into it, it saves the quickstream ID, the response format, and status code to the FHIR response message.
    
    
    7. Reconnect the code activity to the join activity, and compile the business process.

    
    
    
  • Configure the production

    Now that the business process is complete, you will set up your production to include it, along with a second business process responsible for fetching the requested patient data from the database.

    1. From the Management Portal, navigate to Interoperability > Configure > Production. Open FHIRINTGADPKG.FoundationProduction. This production should have two business components: InteropService and InteropOperation.
    2. Click the plus symbol (+) next to Processes to add a new business process with the following settings:
       1. Business Process Class: FHIRInteroperability.BP.GetPatient
       2. Business Process Name: Find Patient
       3. Enable Now: Selected
    3. Click the plus symbol next to Operations to add a new business operation with the following settings:
       1. Business Operation Class: FHIRInteroperability.BO.PatientDB
       2. Business Operation Name: Patient DB
       3. Enable Now: Selected
       This business operation selects a patient from the table, Local_DB.Patient, using the patient Internal ID provided.
    4. Select the InteropService business service and change the Target Config Name to Find Patient. Be sure to click Apply to save this setting.
    5. Start the production.
  • Request patient data

    Now that the production is configured, you can send in a request for patient data to test that the FHIR Facade works as expected. You will first need to get the ID number of a patient in the database, then send a REST request to retrieve this patient data in the FHIR Format.

    1. In the Management Portal, navigate to System Explorer > SQL.
    2. Execute the following query and note the Internal ID of one of the returned patients:

       Select * from Local_DB.Patient

    3. On the lab desktop, click the shortcut to open the Postman REST client.
    4. In Postman, send the following request using the patient ID that you noted.
       • HTTP Request: GET http://localhost:52773/FHIR/Integration/Patient/<InternalID>
       • Header Name: Accept
       • Header Value: application/json+fhir
       The response to this request should show the patient details in FHIR JSON format.
    5. Try sending the request again, using an Internal ID that does not exist. Because this ID does not exist, you should see the HTTP status 404.

    In this exercise, you learned how to populate a FHIR response message within a FHIR Facade. Using a FHIR Facade allows you to accept FHIR requests from external systems and return FHIR data, even if your data is stored in a different format. One of the key steps to implementing a FHIR Facade is correctly populating the FHIR response message so that the data is properly returned to the requesting system.

• What's Next?

  What's Next?
  • Practice setting up a FHIR Facade from start to finish (exercise, 20m).

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