Controlling Simulated Responses

Controlling Responses from Inferno's Simulated DTR Payer Server

During the DTR client tests, client systems are asked to demonstrate that they can handle and complete Questionnaires meeting certain requirements. Some of the scenarios in the client tests require testers to complete Inferno-built Questionnaires to prove conformance to certain requirements. However, many of them allow testers to provide their own Questionnaires and in generaly, Inferno does not have Questionnaires that demonstrate all of the capabilities of the DTR specification, so in practice testers will need to provide some Questionnaires for Inferno to provide back as a part of its DTR payer server simulation. This page describes how testers specify and control Inferno's resposnes to requests for Questionnaires.

Response Templates

Inferno's DTR Payer server simulation includes endpoints for the following three operations:

• Questionnaire/$questionnaire-package
• Questionnaire/$next-question
• ValueSet/$expand

Certain tests provide inputs for response templates that drive Inferno's responses when it has identified an incoming request as associated with the waiting session. In all cases, these templates can include instructions that dynamically change the response based on the request content through inclusion criteria and tokens. The following sections describe the format the response templates for each operation and where dynamic instructions can appear in them.

Questionnaire/$questionnaire-package

A template for $questionnaire-package responses takes the form of a FHIR Parameters resource in json format. Inclusion criteria extensions can appear within the parameter entries. The parameter entries returned for a particular request will be those without inclusion criteria and those with inclusion criteria that are met by the Parameters request body. Thus, the template could define multiple 'packagebundle' and/or 'outcome' parameter entries, but return them only for certain requests, e.g., certain coverages, orders, or Questionnaires. Inclusion criteria extensions will be removed and tokens found within selected parameter entries will be replaced before responding.

Alternatively, the template can be a FHIR OperationOutcome if an error response is appropriate. Tokens are not instantiated within the OperationOutcome.

Questionnaire/$next-question

A template for $next-question responses takes the form of a json array containing one or more FHIR Questionnaire resources in json format. If only a single Questionnaire is provided, it does not have to be wrapped in a json list. Each Questionnaire contains item entries, possibly nested, and these item entries can contain selection criteria.

When a $next-question request is received with a QustionnaireResponse as the body, Inferno first selects the right Questionnaire to use as a template by identifying the the Questionnaire in the template list that matches the contained Questionnaire in the request, based on url and version if present in the request. Inferno then uses the template to select which, if any, item entries from the template to add to the contained Questionnaire. Inferno will add an item if

1. It is not already present within the contained Questionnaire in the request.
2. Its parent was already present or has been added.
3. It has no inclusion criteria or the inclusion criteria are met when evaluated against the QuestionnaireResponse from the request body.

Note that item entries are never removed from the contained Questionnaire. Inclusion criteria extensions will be removed from items before adding them and tokens found within added item entries will be replaced.

Additionally, if no new questions were added and all required questions have answers, the Inferno will mark the QuestionnaireRepsonse as complete by changing the status element to 'completed'.

ValueSet/$expand

TODO - not implemented yet

Specifying Dynamic Content in Response Templates

Inclusion Criteria

Inclusion criteria extension options include:

• urn:inferno:dtr:inclusion-criteria: element valueExpression.expression contains a FHIRPath expression executed against the QuestionnaireResponse from the request. To determine inclusion, the FHIRPath result is interpreted as a boolean where
  • empty collections, collections with multiple entries, and collections with a single false value are interepreted as false.
  • all other collections interpreted as true.
• urn:inferno:dtr:request-range: element valueString contains a single or comma-separated list of 1-indexed request numbers or ranges indicaing the requests that the item can first be included the response. For example, "1,3-5" would mean that the item would be added on request 1, 3, 4, or 5 if its parent were already present or also added.

If multiple criteria are included, all must be met for the item to be included. Recall that if the item is nested under another item, its parent must already present or added for the child to be evaluated for inclusion.

Dynamic Tokens

Tokens of the form {{<fhirpath>}} within response templates are replaced with the results of the <fhirpath>> executed against the request body. The results of the FHIRpath must be one or more strings and results with more than one string are converted into a single string separated by commas. Results that are objects and arrays will be silently discarded.