Release 5 Preview #3

2.47 Resource Subscription - Content

FHIR Infrastructure Work GroupMaturity Level: 2 Trial UseSecurity Category: Business Compartments: Not linked to any defined compartments

The subscription resource describes a particular client's request to be notified about a SubscriptionTopic.

This document contains information about the Subscription resource and details specific to options in it. See Subscriptions for general information about using Subscriptions in FHIR.

The Subscription resource is used to establish proactive event notifications from a FHIR server to another system. Subscribers request event notifications within a predefined SubscriptionTopic that the server supports, and can further refine their notifications by supplying filters. Each SubscriptionTopic resource defines a set of allowed filters (SubscriptionTopic.canFilterBy), which a subscriber refer to within a Subscription resource (Subscription.filterBy). Once a subscription is created, any event matching a specified SubscriptionTopic that meets the filtering criteria will cause a notification to be sent using the provided channel. Notifications are Bundle resources, of type subscription-notification.

Subscriptions are active resources; a server can only accept a subscription if it will execute the specified channel for any resources subsequently received. The subscription is no longer active once it is deleted from the server.

By adjusting Subscription.content, subscribers can request event notifications that include full resource content; or just the ID of the triggering resource; or an empty notification body.

Several channels are defined in the core specification:

  • rest-hook: Notifications are sent via HTTPS POST to the Subscription.endpoint URL (e.g., https://...)
  • websocket: Notifications are sent via WS/S to a client connected via a WebSocket
  • email: Notifications are sent via SMTP/S, S/MIME, or Direct SMTP to the Subscription.endpoint email URI (e.g., mailto:...)
  • message: Notifications are sent via FHIR messaging to the application identified in the Subscription.endpoint URI

Additional channel types can be defined by external implementation guides. See below for further discussion of the various channels.

The Subscription resource is used in the Subscriptions Framework. Information about the Boundaries and Relationships both within the Subscriptions Framework and to other areas of the FHIR specification can be found here.

This resource is referenced by SubscriptionStatus.

This resource does not implement any patterns.

Structure

NameFlagsCard.TypeDescription & Constraintsdoco
.. Subscription TUDomainResourceNotification about a SubscriptionTopic
Elements defined in Ancestors: id, meta, implicitRules, language, text, contained, extension, modifierExtension
... identifier Σ0..*IdentifierAdditional identifiers (business identifier)
... name Σ0..1stringHuman readable name for this subscription
... status ?!Σ1..1coderequested | active | error | off | entered-in-error
Subscription State (Required)
... contact Σ0..*ContactPointContact details for source (e.g. troubleshooting)
... end Σ0..1instantWhen to automatically delete the subscription
... reason Σ0..1stringDescription of why this subscription was created
... filterBy Σ0..*BackboneElementCriteria for narrowing the subscription topic stream
.... resourceType Σ0..1uriAllowed Data type or Resource (reference to definition) for this Subscription
FHIRDefinedType (Extensible)
.... searchParamName Σ1..1stringFilter label defined in SubscriptionTopic
.... searchModifier Σ0..1code= | eq | ne | gt | lt | ge | le | sa | eb | ap | above | below | in | not-in | of-type
Subscription Search Modifier (Required)
.... value Σ1..1stringLiteral value or resource path
... channelType Σ1..1CodingChannel type for notifications
Subscription Channel Type (Extensible)
... endpoint Σ0..1urlWhere the channel points to
... header Σ0..*stringUsage depends on the channel type
... heartbeatPeriod Σ0..1unsignedIntInterval in seconds to send 'heartbeat' notification
... timeout Σ0..1unsignedIntTimeout in seconds to attempt notification delivery
... contentType Σ0..1codeMIME type to send, or omit for no payload
MimeType (Required)
... content Σ0..1codeempty | id-only | full-resource
SubscriptionPayloadContent (Required)
... notificationUrlLocation Σ0..1codenone | full-url | request-response | all
SubscriptionUrlLocation (Required)
... maxCount Σ0..1positiveIntMaximum number of triggering resources included in notification bundles

doco Documentation for this format

UML Diagram (Legend)

Subscription (DomainResource)A formal identifier that is used to identify this code system when it is represented in other formats, or referenced in a specification, model, design or an instanceidentifier : Identifier [0..*]A natural language name identifying the subscriptionname : string [0..1]The status of the subscription, which marks the server state for managing the subscription (this element modifies the meaning of other elements)status : code [1..1] « The status of a subscription. (Strength=Required)SubscriptionState! »The reference to the subscription topic to be notified abouttopic : canonical [1..1] « SubscriptionTopic »Contact details for a human to contact about the subscription. The primary use of this for system administrator troubleshootingcontact : ContactPoint [0..*]The time for the server to turn the subscription offend : instant [0..1]A description of why this subscription is definedreason : string [0..1]The type of channel to send notifications onchannelType : Coding [1..1] « The type of method used to execute a subscription. (Strength=Extensible)SubscriptionChannelType+ »The url that describes the actual end-point to send messages toendpoint : url [0..1]Additional headers / information to send as part of the notificationheader : string [0..*]If present, a 'hearbeat" notification (keepalive) is sent via this channel with an the interval period equal to this elements integer value in seconds. If not present, a heartbeat notification is not sentheartbeatPeriod : unsignedInt [0..1]If present, the maximum amount of time a server will allow before failing a notification attempttimeout : unsignedInt [0..1]The mime type to send the payload in - either application/fhir+xml, or application/fhir+json. The MIME types "text/plain" and "text/html" may also be used for Email subscriptionscontentType : code [0..1] « The mime type of an attachment. Any valid mime type is allowed. (Strength=Required)Mime Types! »How much of the resource content to deliver in the notification payload. The choices are an empty payload, only the resource id, or the full resource contentcontent : code [0..1] « Codes to represent how much resource content to send in the notification payload. (Strength=Required)SubscriptionPayloadContent! »If present, where to place URLs of resources in notificationsnotificationUrlLocation : code [0..1] « The location, in Bundle.entry, where URLs for resources should be located. (Strength=Required)SubscriptionUrlLocation! »If present, the maximum number of triggering resources that will be included in a notification bundle (e.g., a server will not include more than this number of trigger resources in a single notification). Note that this is not a strict limit on the number of entries in a bundle, as dependent resources can be includedmaxCount : positiveInt [0..1]FilterByIf the element is a reference to another resource, this element contains "Reference", and the targetProfile element defines what resources can be referenced. The targetProfile may be a reference to the general definition of a resource (e.g. http://hl7.org/fhir/StructureDefinition/Patient)resourceType : uri [0..1] « Either a resource or a data type, including logical model types. (Strength=Extensible)FHIRDefinedType+ »The filter label (=key) as defined in the `SubscriptionTopic.canfilterBy.searchParamName` elementsearchParamName : string [1..1]The operator to apply to the filter value when determining matches (Search modifiers)searchModifier : code [0..1] « Operator to apply to filter label. (Strength=Required)SubscriptionSearchModifier! »The literal value or resource path as is legal in search - for example, "Patient/123" or "le1950"value : string [1..1]The filter properties to be applied to narrow the subscription topic stream. When multiple filters are applied, evaluates to true if all the conditions are met; otherwise it returns false. (i.e., logical AND)filterBy[0..*]

XML Template

<Subscription xmlns="http://hl7.org/fhir"> doco
 <!-- from Resource: id, meta, implicitRules, and language -->
 <!-- from DomainResource: text, contained, extension, and modifierExtension -->
 <identifier><!-- 0..* Identifier Additional identifiers (business identifier) --></identifier>
 <name value="[string]"/><!-- 0..1 Human readable name for this subscription -->
 <status value="[code]"/><!-- 1..1 requested | active | error | off | entered-in-error -->
 <topic><!-- 1..1 canonical(SubscriptionTopic) Reference to the subscription topic being subscribed to --></topic>
 <contact><!-- 0..* ContactPoint Contact details for source (e.g. troubleshooting) --></contact>
 <end value="[instant]"/><!-- 0..1 When to automatically delete the subscription -->
 <reason value="[string]"/><!-- 0..1 Description of why this subscription was created -->
 <filterBy>  <!-- 0..* Criteria for narrowing the subscription topic stream -->
  <resourceType value="[uri]"/><!-- 0..1 Allowed Data type or Resource (reference to definition) for this Subscription -->
  <searchParamName value="[string]"/><!-- 1..1 Filter label defined in SubscriptionTopic -->
  <searchModifier value="[code]"/><!-- 0..1 = | eq | ne | gt | lt | ge | le | sa | eb | ap | above | below | in | not-in | of-type -->
  <value value="[string]"/><!-- 1..1 Literal value or resource path -->
 </filterBy>
 <channelType><!-- 1..1 Coding Channel type for notifications --></channelType>
 <endpoint value="[url]"/><!-- 0..1 Where the channel points to -->
 <header value="[string]"/><!-- 0..* Usage depends on the channel type -->
 <heartbeatPeriod value="[unsignedInt]"/><!-- 0..1 Interval in seconds to send 'heartbeat' notification -->
 <timeout value="[unsignedInt]"/><!-- 0..1 Timeout in seconds to attempt notification delivery -->
 <contentType value="[code]"/><!-- 0..1 MIME type to send, or omit for no payload -->
 <content value="[code]"/><!-- 0..1 empty | id-only | full-resource -->
 <notificationUrlLocation value="[code]"/><!-- 0..1 none | full-url | request-response | all -->
 <maxCount value="[positiveInt]"/><!-- 0..1 Maximum number of triggering resources included in notification bundles -->
</Subscription>

JSON Template

{doco
  "resourceType" : "Subscription",
  // from Resource: id, meta, implicitRules, and language
  // from DomainResource: text, contained, extension, and modifierExtension
  "identifier" : [{ Identifier }], // Additional identifiers (business identifier)
  "name" : "<string>", // Human readable name for this subscription
  "status" : "<code>", // R!  requested | active | error | off | entered-in-error
  "topic" : { canonical(SubscriptionTopic) }, // R!  Reference to the subscription topic being subscribed to
  "contact" : [{ ContactPoint }], // Contact details for source (e.g. troubleshooting)
  "end" : "<instant>", // When to automatically delete the subscription
  "reason" : "<string>", // Description of why this subscription was created
  "filterBy" : [{ // Criteria for narrowing the subscription topic stream
    "resourceType" : "<uri>", // Allowed Data type or Resource (reference to definition) for this Subscription
    "searchParamName" : "<string>", // R!  Filter label defined in SubscriptionTopic
    "searchModifier" : "<code>", // = | eq | ne | gt | lt | ge | le | sa | eb | ap | above | below | in | not-in | of-type
    "value" : "<string>" // R!  Literal value or resource path
  }],
  "channelType" : { Coding }, // R!  Channel type for notifications
  "endpoint" : "<url>", // Where the channel points to
  "header" : ["<string>"], // Usage depends on the channel type
  "heartbeatPeriod" : "<unsignedInt>", // Interval in seconds to send 'heartbeat' notification
  "timeout" : "<unsignedInt>", // Timeout in seconds to attempt notification delivery
  "contentType" : "<code>", // MIME type to send, or omit for no payload
  "content" : "<code>", // empty | id-only | full-resource
  "notificationUrlLocation" : "<code>", // none | full-url | request-response | all
  "maxCount" : "<positiveInt>" // Maximum number of triggering resources included in notification bundles
}

Turtle Template

@prefix fhir: <http://hl7.org/fhir/> .doco


[ a fhir:Subscription;
  fhir:nodeRole fhir:treeRoot; # if this is the parser root

  # from Resource: .id, .meta, .implicitRules, and .language
  # from DomainResource: .text, .contained, .extension, and .modifierExtension
  fhir:Subscription.identifier [ Identifier ], ... ; # 0..* Additional identifiers (business identifier)
  fhir:Subscription.name [ string ]; # 0..1 Human readable name for this subscription
  fhir:Subscription.status [ code ]; # 1..1 requested | active | error | off | entered-in-error
  fhir:Subscription.topic [ canonical(SubscriptionTopic) ]; # 1..1 Reference to the subscription topic being subscribed to
  fhir:Subscription.contact [ ContactPoint ], ... ; # 0..* Contact details for source (e.g. troubleshooting)
  fhir:Subscription.end [ instant ]; # 0..1 When to automatically delete the subscription
  fhir:Subscription.reason [ string ]; # 0..1 Description of why this subscription was created
  fhir:Subscription.filterBy [ # 0..* Criteria for narrowing the subscription topic stream
    fhir:Subscription.filterBy.resourceType [ uri ]; # 0..1 Allowed Data type or Resource (reference to definition) for this Subscription
    fhir:Subscription.filterBy.searchParamName [ string ]; # 1..1 Filter label defined in SubscriptionTopic
    fhir:Subscription.filterBy.searchModifier [ code ]; # 0..1 = | eq | ne | gt | lt | ge | le | sa | eb | ap | above | below | in | not-in | of-type
    fhir:Subscription.filterBy.value [ string ]; # 1..1 Literal value or resource path
  ], ...;
  fhir:Subscription.channelType [ Coding ]; # 1..1 Channel type for notifications
  fhir:Subscription.endpoint [ url ]; # 0..1 Where the channel points to
  fhir:Subscription.header [ string ], ... ; # 0..* Usage depends on the channel type
  fhir:Subscription.heartbeatPeriod [ unsignedInt ]; # 0..1 Interval in seconds to send 'heartbeat' notification
  fhir:Subscription.timeout [ unsignedInt ]; # 0..1 Timeout in seconds to attempt notification delivery
  fhir:Subscription.contentType [ code ]; # 0..1 MIME type to send, or omit for no payload
  fhir:Subscription.content [ code ]; # 0..1 empty | id-only | full-resource
  fhir:Subscription.notificationUrlLocation [ code ]; # 0..1 none | full-url | request-response | all
  fhir:Subscription.maxCount [ positiveInt ]; # 0..1 Maximum number of triggering resources included in notification bundles
]

Changes since R3

Subscription
Subscription.identifier
  • Added Element
Subscription.name
  • Added Element
Subscription.status
  • Change value set from http://hl7.org/fhir/ValueSet/subscription-status|4.0.0 to http://hl7.org/fhir/ValueSet/subscription-state|4.5.0
Subscription.topic
  • Added Mandatory Element
Subscription.reason
  • Min Cardinality changed from 1 to 0
Subscription.filterBy
  • Added Element
Subscription.filterBy.resourceType
  • Added Element
Subscription.filterBy.searchParamName
  • Added Mandatory Element
Subscription.filterBy.searchModifier
  • Added Element
Subscription.filterBy.value
  • Added Mandatory Element
Subscription.channelType
  • Added Mandatory Element
Subscription.endpoint
  • Added Element
Subscription.header
  • Added Element
Subscription.heartbeatPeriod
  • Added Element
Subscription.timeout
  • Added Element
Subscription.contentType
  • Added Element
Subscription.content
  • Added Element
Subscription.notificationUrlLocation
  • Added Element
Subscription.maxCount
  • Added Element
Subscription.criteria
  • deleted
Subscription.error
  • deleted
Subscription.channel
  • deleted

See the Full Difference for further information

This analysis is available as XML or JSON.

See R3 <--> R4 Conversion Maps (status = 2 tests that all execute ok. 2 fail round-trip testing and all r3 resources are valid.)

Structure

NameFlagsCard.TypeDescription & Constraintsdoco
.. Subscription TUDomainResourceNotification about a SubscriptionTopic
Elements defined in Ancestors: id, meta, implicitRules, language, text, contained, extension, modifierExtension
... identifier Σ0..*IdentifierAdditional identifiers (business identifier)
... name Σ0..1stringHuman readable name for this subscription
... status ?!Σ1..1coderequested | active | error | off | entered-in-error
Subscription State (Required)
... contact Σ0..*ContactPointContact details for source (e.g. troubleshooting)
... end Σ0..1instantWhen to automatically delete the subscription
... reason Σ0..1stringDescription of why this subscription was created
... filterBy Σ0..*BackboneElementCriteria for narrowing the subscription topic stream
.... resourceType Σ0..1uriAllowed Data type or Resource (reference to definition) for this Subscription
FHIRDefinedType (Extensible)
.... searchParamName Σ1..1stringFilter label defined in SubscriptionTopic
.... searchModifier Σ0..1code= | eq | ne | gt | lt | ge | le | sa | eb | ap | above | below | in | not-in | of-type
Subscription Search Modifier (Required)
.... value Σ1..1stringLiteral value or resource path
... channelType Σ1..1CodingChannel type for notifications
Subscription Channel Type (Extensible)
... endpoint Σ0..1urlWhere the channel points to
... header Σ0..*stringUsage depends on the channel type
... heartbeatPeriod Σ0..1unsignedIntInterval in seconds to send 'heartbeat' notification
... timeout Σ0..1unsignedIntTimeout in seconds to attempt notification delivery
... contentType Σ0..1codeMIME type to send, or omit for no payload
MimeType (Required)
... content Σ0..1codeempty | id-only | full-resource
SubscriptionPayloadContent (Required)
... notificationUrlLocation Σ0..1codenone | full-url | request-response | all
SubscriptionUrlLocation (Required)
... maxCount Σ0..1positiveIntMaximum number of triggering resources included in notification bundles

doco Documentation for this format

UML Diagram (Legend)

Subscription (DomainResource)A formal identifier that is used to identify this code system when it is represented in other formats, or referenced in a specification, model, design or an instanceidentifier : Identifier [0..*]A natural language name identifying the subscriptionname : string [0..1]The status of the subscription, which marks the server state for managing the subscription (this element modifies the meaning of other elements)status : code [1..1] « The status of a subscription. (Strength=Required)SubscriptionState! »The reference to the subscription topic to be notified abouttopic : canonical [1..1] « SubscriptionTopic »Contact details for a human to contact about the subscription. The primary use of this for system administrator troubleshootingcontact : ContactPoint [0..*]The time for the server to turn the subscription offend : instant [0..1]A description of why this subscription is definedreason : string [0..1]The type of channel to send notifications onchannelType : Coding [1..1] « The type of method used to execute a subscription. (Strength=Extensible)SubscriptionChannelType+ »The url that describes the actual end-point to send messages toendpoint : url [0..1]Additional headers / information to send as part of the notificationheader : string [0..*]If present, a 'hearbeat" notification (keepalive) is sent via this channel with an the interval period equal to this elements integer value in seconds. If not present, a heartbeat notification is not sentheartbeatPeriod : unsignedInt [0..1]If present, the maximum amount of time a server will allow before failing a notification attempttimeout : unsignedInt [0..1]The mime type to send the payload in - either application/fhir+xml, or application/fhir+json. The MIME types "text/plain" and "text/html" may also be used for Email subscriptionscontentType : code [0..1] « The mime type of an attachment. Any valid mime type is allowed. (Strength=Required)Mime Types! »How much of the resource content to deliver in the notification payload. The choices are an empty payload, only the resource id, or the full resource contentcontent : code [0..1] « Codes to represent how much resource content to send in the notification payload. (Strength=Required)SubscriptionPayloadContent! »If present, where to place URLs of resources in notificationsnotificationUrlLocation : code [0..1] « The location, in Bundle.entry, where URLs for resources should be located. (Strength=Required)SubscriptionUrlLocation! »If present, the maximum number of triggering resources that will be included in a notification bundle (e.g., a server will not include more than this number of trigger resources in a single notification). Note that this is not a strict limit on the number of entries in a bundle, as dependent resources can be includedmaxCount : positiveInt [0..1]FilterByIf the element is a reference to another resource, this element contains "Reference", and the targetProfile element defines what resources can be referenced. The targetProfile may be a reference to the general definition of a resource (e.g. http://hl7.org/fhir/StructureDefinition/Patient)resourceType : uri [0..1] « Either a resource or a data type, including logical model types. (Strength=Extensible)FHIRDefinedType+ »The filter label (=key) as defined in the `SubscriptionTopic.canfilterBy.searchParamName` elementsearchParamName : string [1..1]The operator to apply to the filter value when determining matches (Search modifiers)searchModifier : code [0..1] « Operator to apply to filter label. (Strength=Required)SubscriptionSearchModifier! »The literal value or resource path as is legal in search - for example, "Patient/123" or "le1950"value : string [1..1]The filter properties to be applied to narrow the subscription topic stream. When multiple filters are applied, evaluates to true if all the conditions are met; otherwise it returns false. (i.e., logical AND)filterBy[0..*]

XML Template

<Subscription xmlns="http://hl7.org/fhir"> doco
 <!-- from Resource: id, meta, implicitRules, and language -->
 <!-- from DomainResource: text, contained, extension, and modifierExtension -->
 <identifier><!-- 0..* Identifier Additional identifiers (business identifier) --></identifier>
 <name value="[string]"/><!-- 0..1 Human readable name for this subscription -->
 <status value="[code]"/><!-- 1..1 requested | active | error | off | entered-in-error -->
 <topic><!-- 1..1 canonical(SubscriptionTopic) Reference to the subscription topic being subscribed to --></topic>
 <contact><!-- 0..* ContactPoint Contact details for source (e.g. troubleshooting) --></contact>
 <end value="[instant]"/><!-- 0..1 When to automatically delete the subscription -->
 <reason value="[string]"/><!-- 0..1 Description of why this subscription was created -->
 <filterBy>  <!-- 0..* Criteria for narrowing the subscription topic stream -->
  <resourceType value="[uri]"/><!-- 0..1 Allowed Data type or Resource (reference to definition) for this Subscription -->
  <searchParamName value="[string]"/><!-- 1..1 Filter label defined in SubscriptionTopic -->
  <searchModifier value="[code]"/><!-- 0..1 = | eq | ne | gt | lt | ge | le | sa | eb | ap | above | below | in | not-in | of-type -->
  <value value="[string]"/><!-- 1..1 Literal value or resource path -->
 </filterBy>
 <channelType><!-- 1..1 Coding Channel type for notifications --></channelType>
 <endpoint value="[url]"/><!-- 0..1 Where the channel points to -->
 <header value="[string]"/><!-- 0..* Usage depends on the channel type -->
 <heartbeatPeriod value="[unsignedInt]"/><!-- 0..1 Interval in seconds to send 'heartbeat' notification -->
 <timeout value="[unsignedInt]"/><!-- 0..1 Timeout in seconds to attempt notification delivery -->
 <contentType value="[code]"/><!-- 0..1 MIME type to send, or omit for no payload -->
 <content value="[code]"/><!-- 0..1 empty | id-only | full-resource -->
 <notificationUrlLocation value="[code]"/><!-- 0..1 none | full-url | request-response | all -->
 <maxCount value="[positiveInt]"/><!-- 0..1 Maximum number of triggering resources included in notification bundles -->
</Subscription>

JSON Template

{doco
  "resourceType" : "Subscription",
  // from Resource: id, meta, implicitRules, and language
  // from DomainResource: text, contained, extension, and modifierExtension
  "identifier" : [{ Identifier }], // Additional identifiers (business identifier)
  "name" : "<string>", // Human readable name for this subscription
  "status" : "<code>", // R!  requested | active | error | off | entered-in-error
  "topic" : { canonical(SubscriptionTopic) }, // R!  Reference to the subscription topic being subscribed to
  "contact" : [{ ContactPoint }], // Contact details for source (e.g. troubleshooting)
  "end" : "<instant>", // When to automatically delete the subscription
  "reason" : "<string>", // Description of why this subscription was created
  "filterBy" : [{ // Criteria for narrowing the subscription topic stream
    "resourceType" : "<uri>", // Allowed Data type or Resource (reference to definition) for this Subscription
    "searchParamName" : "<string>", // R!  Filter label defined in SubscriptionTopic
    "searchModifier" : "<code>", // = | eq | ne | gt | lt | ge | le | sa | eb | ap | above | below | in | not-in | of-type
    "value" : "<string>" // R!  Literal value or resource path
  }],
  "channelType" : { Coding }, // R!  Channel type for notifications
  "endpoint" : "<url>", // Where the channel points to
  "header" : ["<string>"], // Usage depends on the channel type
  "heartbeatPeriod" : "<unsignedInt>", // Interval in seconds to send 'heartbeat' notification
  "timeout" : "<unsignedInt>", // Timeout in seconds to attempt notification delivery
  "contentType" : "<code>", // MIME type to send, or omit for no payload
  "content" : "<code>", // empty | id-only | full-resource
  "notificationUrlLocation" : "<code>", // none | full-url | request-response | all
  "maxCount" : "<positiveInt>" // Maximum number of triggering resources included in notification bundles
}

Turtle Template

@prefix fhir: <http://hl7.org/fhir/> .doco


[ a fhir:Subscription;
  fhir:nodeRole fhir:treeRoot; # if this is the parser root

  # from Resource: .id, .meta, .implicitRules, and .language
  # from DomainResource: .text, .contained, .extension, and .modifierExtension
  fhir:Subscription.identifier [ Identifier ], ... ; # 0..* Additional identifiers (business identifier)
  fhir:Subscription.name [ string ]; # 0..1 Human readable name for this subscription
  fhir:Subscription.status [ code ]; # 1..1 requested | active | error | off | entered-in-error
  fhir:Subscription.topic [ canonical(SubscriptionTopic) ]; # 1..1 Reference to the subscription topic being subscribed to
  fhir:Subscription.contact [ ContactPoint ], ... ; # 0..* Contact details for source (e.g. troubleshooting)
  fhir:Subscription.end [ instant ]; # 0..1 When to automatically delete the subscription
  fhir:Subscription.reason [ string ]; # 0..1 Description of why this subscription was created
  fhir:Subscription.filterBy [ # 0..* Criteria for narrowing the subscription topic stream
    fhir:Subscription.filterBy.resourceType [ uri ]; # 0..1 Allowed Data type or Resource (reference to definition) for this Subscription
    fhir:Subscription.filterBy.searchParamName [ string ]; # 1..1 Filter label defined in SubscriptionTopic
    fhir:Subscription.filterBy.searchModifier [ code ]; # 0..1 = | eq | ne | gt | lt | ge | le | sa | eb | ap | above | below | in | not-in | of-type
    fhir:Subscription.filterBy.value [ string ]; # 1..1 Literal value or resource path
  ], ...;
  fhir:Subscription.channelType [ Coding ]; # 1..1 Channel type for notifications
  fhir:Subscription.endpoint [ url ]; # 0..1 Where the channel points to
  fhir:Subscription.header [ string ], ... ; # 0..* Usage depends on the channel type
  fhir:Subscription.heartbeatPeriod [ unsignedInt ]; # 0..1 Interval in seconds to send 'heartbeat' notification
  fhir:Subscription.timeout [ unsignedInt ]; # 0..1 Timeout in seconds to attempt notification delivery
  fhir:Subscription.contentType [ code ]; # 0..1 MIME type to send, or omit for no payload
  fhir:Subscription.content [ code ]; # 0..1 empty | id-only | full-resource
  fhir:Subscription.notificationUrlLocation [ code ]; # 0..1 none | full-url | request-response | all
  fhir:Subscription.maxCount [ positiveInt ]; # 0..1 Maximum number of triggering resources included in notification bundles
]

Changes since Release 3

Subscription
Subscription.identifier
  • Added Element
Subscription.name
  • Added Element
Subscription.status
  • Change value set from http://hl7.org/fhir/ValueSet/subscription-status|4.0.0 to http://hl7.org/fhir/ValueSet/subscription-state|4.5.0
Subscription.topic
  • Added Mandatory Element
Subscription.reason
  • Min Cardinality changed from 1 to 0
Subscription.filterBy
  • Added Element
Subscription.filterBy.resourceType
  • Added Element
Subscription.filterBy.searchParamName
  • Added Mandatory Element
Subscription.filterBy.searchModifier
  • Added Element
Subscription.filterBy.value
  • Added Mandatory Element
Subscription.channelType
  • Added Mandatory Element
Subscription.endpoint
  • Added Element
Subscription.header
  • Added Element
Subscription.heartbeatPeriod
  • Added Element
Subscription.timeout
  • Added Element
Subscription.contentType
  • Added Element
Subscription.content
  • Added Element
Subscription.notificationUrlLocation
  • Added Element
Subscription.maxCount
  • Added Element
Subscription.criteria
  • deleted
Subscription.error
  • deleted
Subscription.channel
  • deleted

See the Full Difference for further information

This analysis is available as XML or JSON.

See R3 <--> R4 Conversion Maps (status = 2 tests that all execute ok. 2 fail round-trip testing and all r3 resources are valid.)

 

See the Profiles & Extensions and the alternate definitions: Master Definition XML + JSON, XML Schema/Schematron + JSON Schema, ShEx (for Turtle) + see the extensions, the spreadsheet version & the dependency analysis a

PathDefinitionTypeReference
Subscription.status The status of a subscription.RequiredSubscriptionState
Subscription.filterBy.resourceType Either a resource or a data type, including logical model types.ExtensibleFHIRDefinedType
Subscription.filterBy.searchModifier Operator to apply to filter label.RequiredSubscriptionSearchModifier
Subscription.channelType The type of method used to execute a subscription.ExtensibleSubscriptionChannelType
Subscription.contentType The mime type of an attachment. Any valid mime type is allowed.RequiredMime Types
Subscription.content Codes to represent how much resource content to send in the notification payload.RequiredSubscriptionPayloadContent
Subscription.notificationUrlLocation The location, in Bundle.entry, where URLs for resources should be located.RequiredSubscriptionUrlLocation

Trial-Use Note:

TODO

  1. Updates to "Managing Subscriptions and Errors"

    • Discuss error codes (Extensible Codeable Concept)
    • Define basic error codes here
    • Need to discuss eventCount and error detection (insert appropriate examples/workflows)
  2. Updates to "Tracking Subscription Notifications" SHOULD define what the AuditEvent looks like

Applications are responsible for following FHIR security guidance. Some recommendations specific to subscriptions are provided on the Subscriptions Framework page.

There are three options available when specifying the contents of a Notification: empty, id-only, and full-resource. These options change the level of detail conveyed in the notification Bundle.

When deciding which payload type to request, systems SHOULD consider both ease of processing and security of PHI. To mitigate the risk of information leakage, systems SHOULD use the minimum level of detail consistent with the use case. In practice, id-only provides a good balance between security and performance for many real-world scenarios.

If a server will not honor a payload type (e.g., will not send full-resource over HTTP), it SHOULD reject the Subscription request, but the server MAY accept the subscription with modificaitons.

An example notification with an empty payload can be found here.

With the content type of empty, all information about the resources involved in triggering the notification is only available via channels other than the Subscription itself (e.g., the REST API). This mitigates many security concerns by both removing most PHI from the notification and allows servers to consolidate authorization and authentication logic. When the subscriber receives a notification of this type, it may query the server to fetch all the relevant resources based on the SubscriptionTopic and applicable filters. The client might include a _since= query parameter, supplying its last query timestamp to retrieve only the most recent resources. For example, if the notification is for a topic about patient admission, the subscriber will generally query for recent Encounters for a patient or group of patients, then fetch them as needed.

When the content type is empty, notification bundles SHALL not contain Bundle.entry elements other than the SubscriptionStatus for the notification.

An example notification with an id-only payload can be found here.

With the content type of id-only, the resources involved in triggering the notification are only available through other channels (e.g., REST API), but notifications include URLs which can be used to access those resources. This allows servers to consolidate authorization and authentication logic, while removing the need for expensive queries by subscribers. When a subscriber receives a notification of this type, it may directly fetch all the relevant resources using the supplied resource ids. For example, the if the notification is for a topic about patient admission, the subscriber may fetch the Encounter(s) for a patient or group of patients.

When the content type is id-only, notification bundles SHALL contain, in addition to the SubscriptionStatus, at least one Bundle.entry for each resource relevant to the notification. For example, a notification for a topic based on Encounter SHALL include a reference to the Encounter and MAY include additional resources deemed relevant (e.g., the linked Patient).

Each Bundle.entry for id-only notification SHALL contain a relevant resource URL in the fullUrl, request, and/or response elements. The Subscription's notificationUrlLocation element describes the behavior which should be used.

An example notification with a full-resource payload can be found here.

With the content type of full-resource, the resources involved in triggering the notification are included in the notification bundle. When a subscriber receives a notification of this type, resources are already present in the bundle, though the subscriber may need to fetch additional resources from the server. For example, the if the notification is for a topic about patient admission, the subscriber may require related Observation resources.

When the content type is full-resource, notification bundles SHALL contain, in addition to the SubscriptionStatus, at least one Bundle.entry for each resource relevant to the notification. For example, a notification for a topic based on Encounter SHALL include an Encounter and MAY include additional resources deemed relevant (e.g., the relevant Patient).

In most scenarios, each Bundle.entry for a full-resource notification SHALL contain a relevant resource in the resource element. In some scenarios, it is not possible to include the resource, in which case entry.request and/or entry.response are required. For example, in the case of a notification about a deleted resource, the server may no longer have access to the resource. In this case, information in the entry.response is critical for a subscriber to process the notification (e.g., the etag).

When a Subscription is created for a REST Hook channel type, the server SHALL set initial status to requested, pending verification of the nominated endpoint URL. After a successful handshake notification has been sent and accepted, the server SHALL update the status to active. Any errors in the initial handshake SHALL result in the status being changed to error.

To receive notifications via HTTP/S POST, a client should request a subscription with the channel type (Subscription.channelType) of rest-hook (from the subscription-channel-type Code System) and set the endpoint (Subscription.endpoint) to the appropriate client URL. Note that this URL must be accessible by the hosting server.

To convey an event notification, the server POSTs a Bundle to the client's nominated endpoint URL per the format requests in the Subscription. The content-type of the POST SHALL match the contentType (channel.contentType) requested during creation of the Subscription. Each Subscription.header value SHALL be conveyed as an HTTP request header.

An example workflow for establishing a rest-hook subscription is included below.

Diagram with a worflow for a Subscription using REST hooks
  1. Client creates a Subscription with the channelType set to rest-hook.
  2. Server responds with a success code and creates the subscription with a state of requested.
  3. Server performs an HTTP POST to the requested endpoint with a handshake notification.
  4. Client Endpoint accepts the POST and returns a success HTTP code (e.g., 200).
  5. Server may send a notification of type heartbeat at any time.
  6. Server may send a notificaiton of type event-notificaiton at any time.

HTTP is neither a secure nor an encrypted channel. It is strongly recommended that production implementations refuse requests to send notifications to URLs using the HTTP protocol (use HTTPS instead).

HTTP does not provide endpoint verification. It is strongly recommended that implementations refuse requests to send notifications to URLs using the HTTP protocol (use HTTPS instead).

While the primary interface for FHIR servers is the FHIR REST API, notifications need not occur via REST. Indeed, some subscribers may be unable to expose an outward-facing HTTP server to receive triggered notifications. For example, a pure client-side Web app or mobile app may want to subscribe to a data feed without polling using the /history operation. This can be accomplished using a websocket notification channel.

A client can declare its intention to receive notifications via Web Sockets by requesting a subscription with the channel type (Subscription.channelType) of websocket (from the subscription-channel-type Code System).

An example workflow for receiving notifications via websockets is shown below:

Diagram with a worflow for a Subscription using websockets
  1. Client creates a Subscription with the channelType set to websocket.
  2. Server responds with a success code and creates the subscription.
  3. Client requests FHIR server's CapabilityStatement to find the server's websocket URL via the websocket extension.
  4. Server returns its CapabilityStatement.
  5. Client connects to the server via websockets (ws:// or wss://).
  6. Client requests a websocket binding token, by invoking the $get-ws-binding-token operation via REST. Note: this call is intended to be repeated as necessary (e.g., prior to a token expiring, a client should request a new one).
  7. Server returns Parameters with a token and an expiration.
  8. Client sends a bind-with-token message via websockets, with the token provided by the server. Note: this operation can be repeated concurrently for multiple subscriptions, and serially for continued operation over a single websocket connection.
  9. Server sends one or more handshake messages via websockets (one per Subscription included in the token). Note: some servers may additionally send one or more event-notification messages at this time (e.g., all messages since last connected, last 'n' messages, etc.). Clients are expected to handle either flow.
  10. Server may send a heartbeat message via websockets at any time.
  11. Server may send an event-notification message via websockets at any time.
  12. Either the server or the client may close the websocket connection.

Note: all notifications sent from the server SHALL be in the format specified by the Subscription it is for (e.g., contentType and content fields).

Trial-Use Note: The Websocket channel type needs more testing and feedback to ensure all requirements are met before finalizing the specification.

WebSocket security poses several challenges specific to the channel. When implementing websockets for notifications, please keep in mind the following list of some areas of concern:

  • Authentication of WebSockets is not generically interoperable with JWT or other 'Authentication header' protocols - WS and WSS do NOT allow for the required headers.
  • Given client limitations on concurrent WebSocket connections (commonly 6), it is recommended that a single connection be able to authenticate to multiple Subscription resources.
  • Unlike HTTP/S requests, WebSockets can be long-lived. Because of this, the case of revoking access of an active connection must be considered.

While the primary interface for FHIR servers is the FHIR REST API, notifications need not occur via REST. Indeed, some subscribers may be unable to maintain an outward-facing HTTP server to receive triggered notifications. For example, a public health organization may want to be notified of outbreaks of various illnesses. This can be accomplished using an email notification channel.

A client can declare its intention to receive notifications via Email by requesting a subscription with the channel type (Subscription.channelType) of email (from the subscription-channel-type Code System) and setting the endpoint (Subscription.endpoint) to the appropriate email URI (e.g., mailto:public_health_notifications@example.org).

The server will send a new message each time a notification should be sent (e.g., per event or per batch). The server will create a message based on the values present in the Subscription.contentType and Subscription.content fields. If a server cannot honor the requested combination, the server should reject the Subscription request rather than send unexpected email messages.

The email channel sets two guidelines about content:

  • Message Body content SHALL be human readable
  • Message Attachments SHOULD be machine readable

Due to these guidelines, the Subscription.contentType refers to the content of the body of the message. Attachment type information can be appended as a MIME parameter, for example:

  • text/plain: a plain-text body with no attachment
  • text/html: an HTML body with no attachment
  • text/plain;attach=application/fhir+json: a plain-text body with a FHIR JSON bundle attached
  • text/html;attach=application/fhir+xml: an HTML body with a FHIR XML bundle attached

The Subscription.content field SHALL be applied to any attachments, and MAY be applied to body contents (depending on server implementation). However, a server must not include a body which exceeds the specified content level. For example, a server may choose to always include a standard message in the body of the message containing no PHI and vary the attachment, but cannot include PHI in the body of an email when the content is set to empty.

An example workflow using the email channel type is included below.

Diagram with a worflow for a Subscription using email
  1. Client creates a Subscription with the channelType set to email.
  2. Server responds with a success code and creates the subscription with a state of either requested or active.
  3. Optional: Server sends a email message to the requested endpoint with a handshake notification. If the subscription was set to requested, it should be updated to active after successfully sending the email (pending additional steps such as user confirmation, etc.).
  4. Server may send an email for a notification of type heartbeat at any time.
  5. Server may send an email for a notificaiton of type event-notificaiton at any time.

Email (SMTP) is not a secure channel. Implementers must ensure that any messages containing PHI have been secured according to their policy requirements (e.g., use of a system such as Direct ).

There are times when it is desireable to use Subscriptions as a communication channel between FHIR servers. This can be accomplished using a Subscription with the channel type of message.

To receive notifications via messaging, a client should request a subscription with the channel type (Subscription.channelType) of message and set the endpoint (Subscription.endpoint) to the destination FHIR server base URL. Note that this URL must be accessible by the hosting server.

The FHIR server hosting the subscription (server) will send FHIR messages to the destination FHIR server (endpoint) as needed. These messages will, as the contents of the message, have a fully-formed subscription-notification Bundle. An example message can be found here.

An example workflow using the message channel type is included below.

Diagram with a worflow for a Subscription using FHIR messaging
  1. Client creates a Subscription with the channelType set to message.
  2. Server responds with a success code and creates the subscription with a state of requested.
  3. Server sends a FHIR Message to the requested endpoint with a handshake notification.
  4. Client Endpoint accepts the Message and returns success.
  5. Server may send a Message containing a notification of type heartbeat at any time.
  6. Server may send a Message containing a notificaiton of type event-notificaiton at any time.

Trial-Use Note: The Messaging channel type needs more testing and feedback to ensure all requirements are met before finalizing the specification.

Servers MAY require that the end-point is white-listed prior to allowing these kinds of subscriptions. Additionally, servers MAY impose authorization/authentication requirements for server to server communication (e.g., certificate pinning, etc.).

Defining a new channel type requires clear communication to implementers of both clients and servers around requirements and expectations. Below are some areas which should be considered when creating a channel. Anyone defining a channel type is encouraged to publish their definition at registry.fhir.org .

Trial-Use Note: Warning: This section is still in early drafting.

At a minimum, the following items should be defined:

  • A generally useful name for Subscription.channelType (e.g., 'secure-mq' isntead of 'channel0012')
  • The type of data required in Subscription.endpoint (e.g., URI, etc.)
  • The meaning of the Subscription.header field values (e.g., REST-hook defines as Auth headers included in a POST)
  • Any variations on MIME types for Subscription.contentType (e.g., email defines this as the email body, with allowable attachments.)
  • Whether heartbeat notifications are used (and guidance on timings if they are)
  • Defining a channel has security implications.
  • If the channel CANNOT be secured, that should be stated with a warning not to transfer PHI.
  • If the channel is/can be scured, guidance should be given on how configurations relate to PHI safety:
    • Does the channel determine the legitimacy of both endpoints?
    • Is the channel secure for third-party monitoring?
    • ...

The subscription resource is authored by the client with an initial status of requested. A new subscription is created on the server using the RESTful create or update interaction. After a successful transaction, the client parses the Location header and saves the new Subscription's logical id for use in subsequent operations.

When the server receives a subscription, it SHOULD check that it is prepared to accept/process the subscription. If it is, it sets the subscription to requested and process it like a normal create. If it isn't, it SHOULD return an error with an OperationOutcome instead of processing the create.

The criteria are subject to the same limitations as the client that created it, such as access to patient compartments etc. Note that the subscription MAY remain active after the client access tokens expire.

Once the server has activated the subscription, it sets the status to active (note: the server may do this as it accepts the resource if it wants).

An appropriately authorized client can use search and/or history operations to see what subscriptions are currently active on the server. Once the subscription is no longer desired, the client deletes the subscription from the server.

The server may retry the notification a fixed number of times and/or refer errors to its own alert logs. If the notification fails, the server SHOULD set the status to error and mark the error in the resource. If the notification succeeds, the server SHOULD update the status to active and may remove any error codes. If a subscription fails consistently a server may choose set the subscription status to off and stop trying to send notifications.

Errors a server wishes to make accessible to clients are stored in Subscription.error. Servers should provide a mechanism for clearing errors (e.g., when resetting a Subscription.status back to requested after an error). Since Subscription.error represents server errors, a server SHOULD NOT allow clients to add errors.

Search parameters for this resource. The common parameters also apply. See Searching for more information about searching in REST, messaging, and services.

NameTypeDescriptionExpressionIn Common
contacttokenContact details for the subscriptionSubscription.contact
identifiertokenA subscription identifierSubscription.identifier
payloadtokenThe mime-type of the notification payload
status NtokenThe current state of the subscriptionSubscription.status
typetokenThe type of channel for the sent notifications
urluriThe uri that will receive the notifications