Channel Types

The following sections outline the various channel types (delivery mechanisms) that are supported by Smile CDR.

Channel Type: rest-hook

The rest-hook channel type specifies that Smile CDR should create an HTTP REST request to a FHIR endpoint any time that a resource changes that matches the given subscription.

For example, suppose a Subscription is created with the following values:

{
  "resourceType": "Subscription",
  "status": "requested",
  "criteria": "Patient?name=smith",
  "channel": {
    "type": "rest-hook",
    "endpoint": "http://example.com:8080/fhir",
    "payload": "application/json"
  }
}

In this case, if a new Patient is created with the name "Smith", and the FHIR Storage module assigns it an ID of 123, an HTTP PUT will be performed to the address http://example.com:8080/fhir/Patient/123 with the resource body as the payload.

Channel Type: email

The email channel type uses an SMTP relay to deliver notification about changed resources to the recipient. The contents, recipient, and body of the transmitted email may be specified using properties in the Subscription.

For example, the following example shows a simple email subscription:

{
  "resourceType": "Subscription",
  "status": "requested",
  "reason": "Monitor new emergency department encounters",
  "criteria": "Encounter?class=http://hl7.org/fhir/v3/ActCode|EMER",
  "channel": {
    "type": "email",
    "endpoint": "mailto:foo@example.com"
  }
}

Note the following fields:

• endpoint – The endpoint must be set to a `mailto:` URI that will be treated as the recipient email address. Additional recipients may be specified by using comma-separated values (e.g. mailto:recipient1@example.com,recipient2@example.com).

Email Extensions

HAPI FHIR and Smile CDR provide several extensions that may be placed on the Subscription.channel element:

An example resource including these extensions is shown below.

{
  "resourceType": "Subscription",
  "status": "requested",
  "reason": "Monitor new emergency department encounters",
  "criteria": "Encounter?class=http://hl7.org/fhir/v3/ActCode|EMER",
  "channel": {
    "extension": [
      {
        "url": "http://hapifhir.io/fhir/StructureDefinition/subscription-email-from",
        "valueUri": "mailto:myfrom@from.com"
      },
      {
        "url": "http://hapifhir.io/fhir/StructureDefinition/subscription-email-subject-template",
        "valueString": "This is a subject."
      }
    ],
    "type": "email",
    "endpoint": "mailto:foo@example.com"
  }
}

Channel Type: message

The message channel type specifies that Smile CDR should submit the matched resource to the named broker channel (e.g. the named JMS queue or a named Kafka topic).

For example, suppose a Subscription is created with the following values:

{
  "resourceType": "Subscription",
  "status": "requested",
  "criteria": "Patient?name=smith",
  "channel": {
    "type": "message",
    "endpoint": "channel:my-queue-name",
    "payload": "application/json"
  }
}

In this case, if a new Patient is created with the name "Smith", and the FHIR Storage module assigns it an ID of 123, a ResourceModifiedJsonMessage will submitted to the "my-queue-name" queue.