Scope and Usage

Subscription can be used to get notified about changes to resources. Currently only subscription on these resources can be created:

• QuestionnaireResponse
• PlanDefinition
• CarePlan
• Task

• Differential Table
• Key Elements Table
• Snapshot Table
• Statistics/References
• All

This structure is derived from Subscription

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Subscription		0..*	Subscription	Server push subscription criteria
Subscription.criteria	C	1..1	string	Rule for server push Constraints: ohh-subscription-criteria
Subscription.channel
Subscription.channel.type		1..1	code	rest-hook | websocket | email | sms | message Fixed Value: rest-hook (no extensions allowed)
Documentation for this format

Constraints

Id	Grade	Path(s)	Description	Expression
ohh-subscription-criteria	error	Subscription.criteria	Criteria can only be on QuestionnaireResponse, PlanDefinition, CarePlan or Task	matches('^(QuestionnaireResponse|PlanDefinition|CarePlan|Task).*')

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Subscription		0..*	Subscription	Server push subscription criteria
Subscription.implicitRules	?! This element is a modifier element. Σ This element is included in summaries.	0..1	uri	A set of rules under which this content was created
Subscription.modifierExtension	?! This element is a modifier element.	0..*	Extension	Extensions that cannot be ignored
Subscription.status	?! This element is a modifier element. Σ This element is included in summaries.	1..1	code	requested | active | error | off Binding: SubscriptionStatus (required): The status of a subscription.
Subscription.reason	Σ This element is included in summaries.	1..1	string	Description of why this subscription was created
Subscription.criteria	Σ This element is included in summaries. C	1..1	string	Rule for server push Constraints: ohh-subscription-criteria
Subscription.channel	Σ This element is included in summaries.	1..1	BackboneElement	The channel on which to report matches to the criteria
Subscription.channel.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored even if unrecognized
Subscription.channel.type	Σ This element is included in summaries.	1..1	code	rest-hook | websocket | email | sms | message Binding: SubscriptionChannelType (required): The type of method used to execute a subscription. Fixed Value: rest-hook (no extensions allowed)
Documentation for this format

Terminology Bindings

Path	Status	Usage	ValueSet	Version	Source
Subscription.status	Base	required	SubscriptionStatus	📍4.0.1	FHIR Std.
Subscription.channel.​type	Base	required	SubscriptionChannelType	📍4.0.1	FHIR Std.

Constraints

Id	Grade	Path(s)	Description	Expression
dom-2	error	Subscription	If the resource is contained in another resource, it SHALL NOT contain nested Resources	contained.contained.empty()
dom-3	error	Subscription	If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource	contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().as(canonical) | %resource.descendants().as(uri) | %resource.descendants().as(url))) or descendants().where(reference = '#').exists() or descendants().where(as(canonical) = '#').exists() or descendants().where(as(canonical) = '#').exists()).not()).trace('unmatched', id).empty()
dom-4	error	Subscription	If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated	contained.meta.versionId.empty() and contained.meta.lastUpdated.empty()
dom-5	error	Subscription	If a resource is contained in another resource, it SHALL NOT have a security label	contained.meta.security.empty()
dom-6	best practice	Subscription	A resource should have narrative for robust management	text.`div`.exists()
ele-1	error	**ALL** elements	All FHIR elements must have a @value or children	hasValue() or (children().count() > id.count())
ext-1	error	**ALL** extensions	Must have either extensions or value[x], not both	extension.exists() != value.exists()
ohh-subscription-criteria	error	Subscription.criteria	Criteria can only be on QuestionnaireResponse, PlanDefinition, CarePlan or Task	matches('^(QuestionnaireResponse|PlanDefinition|CarePlan|Task).*')

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Subscription		0..*	Subscription	Server push subscription criteria
Subscription.id	Σ This element is included in summaries.	0..1	id	Logical id of this artifact
Subscription.meta	Σ This element is included in summaries.	0..1	Meta	Metadata about the resource
Subscription.implicitRules	?! This element is a modifier element. Σ This element is included in summaries.	0..1	uri	A set of rules under which this content was created
Subscription.language		0..1	code	Language of the resource content Binding: CommonLanguages (preferred): A human language. Additional Bindings Purpose AllLanguages Max Binding
Subscription.text		0..1	Narrative	Text summary of the resource, for human interpretation This profile does not constrain the narrative in regard to content, language, or traceability to data elements
Subscription.contained		0..*	Resource	Contained, inline Resources
Subscription.extension		0..*	Extension	Additional content defined by implementations
Subscription.modifierExtension	?! This element is a modifier element.	0..*	Extension	Extensions that cannot be ignored
Subscription.status	?! This element is a modifier element. Σ This element is included in summaries.	1..1	code	requested | active | error | off Binding: SubscriptionStatus (required): The status of a subscription.
Subscription.contact	Σ This element is included in summaries.	0..*	ContactPoint	Contact details for source (e.g. troubleshooting)
Subscription.end	Σ This element is included in summaries.	0..1	instant	When to automatically delete the subscription
Subscription.reason	Σ This element is included in summaries.	1..1	string	Description of why this subscription was created
Subscription.criteria	Σ This element is included in summaries. C	1..1	string	Rule for server push Constraints: ohh-subscription-criteria
Subscription.error	Σ This element is included in summaries.	0..1	string	Latest error note
Subscription.channel	Σ This element is included in summaries.	1..1	BackboneElement	The channel on which to report matches to the criteria
Subscription.channel.id		0..1	string	Unique id for inter-element referencing
Subscription.channel.extension		0..*	Extension	Additional content defined by implementations
Subscription.channel.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored even if unrecognized
Subscription.channel.type	Σ This element is included in summaries.	1..1	code	rest-hook | websocket | email | sms | message Binding: SubscriptionChannelType (required): The type of method used to execute a subscription. Fixed Value: rest-hook (no extensions allowed)
Subscription.channel.endpoint	Σ This element is included in summaries.	0..1	url	Where the channel points to
Subscription.channel.payload	Σ This element is included in summaries.	0..1	code	MIME type to send, or omit for no payload Binding: Mime Types (required): The mime type of an attachment. Any valid mime type is allowed.
Subscription.channel.header	Σ This element is included in summaries.	0..*	string	Usage depends on the channel type
Documentation for this format

Terminology Bindings

Path	Status	Usage	ValueSet	Version	Source
Subscription.language	Base	preferred	Common Languages	📍4.0.1	FHIR Std.
Subscription.status	Base	required	SubscriptionStatus	📍4.0.1	FHIR Std.
Subscription.channel.​type	Base	required	SubscriptionChannelType	📍4.0.1	FHIR Std.
Subscription.channel.​payload	Base	required	MimeType	📍4.0.1	FHIR Std.

Constraints

Id	Grade	Path(s)	Description	Expression
dom-2	error	Subscription	If the resource is contained in another resource, it SHALL NOT contain nested Resources	contained.contained.empty()
dom-3	error	Subscription	If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource	contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().as(canonical) | %resource.descendants().as(uri) | %resource.descendants().as(url))) or descendants().where(reference = '#').exists() or descendants().where(as(canonical) = '#').exists() or descendants().where(as(canonical) = '#').exists()).not()).trace('unmatched', id).empty()
dom-4	error	Subscription	If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated	contained.meta.versionId.empty() and contained.meta.lastUpdated.empty()
dom-5	error	Subscription	If a resource is contained in another resource, it SHALL NOT have a security label	contained.meta.security.empty()
dom-6	best practice	Subscription	A resource should have narrative for robust management	text.`div`.exists()
ele-1	error	**ALL** elements	All FHIR elements must have a @value or children	hasValue() or (children().count() > id.count())
ext-1	error	**ALL** extensions	Must have either extensions or value[x], not both	extension.exists() != value.exists()
ohh-subscription-criteria	error	Subscription.criteria	Criteria can only be on QuestionnaireResponse, PlanDefinition, CarePlan or Task	matches('^(QuestionnaireResponse|PlanDefinition|CarePlan|Task).*')

Differential View

This structure is derived from Subscription

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Subscription		0..*	Subscription	Server push subscription criteria
Subscription.criteria	C	1..1	string	Rule for server push Constraints: ohh-subscription-criteria
Subscription.channel
Subscription.channel.type		1..1	code	rest-hook | websocket | email | sms | message Fixed Value: rest-hook (no extensions allowed)
Documentation for this format

Constraints

Id	Grade	Path(s)	Description	Expression
ohh-subscription-criteria	error	Subscription.criteria	Criteria can only be on QuestionnaireResponse, PlanDefinition, CarePlan or Task	matches('^(QuestionnaireResponse|PlanDefinition|CarePlan|Task).*')

Key Elements View

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Subscription		0..*	Subscription	Server push subscription criteria
Subscription.implicitRules	?! This element is a modifier element. Σ This element is included in summaries.	0..1	uri	A set of rules under which this content was created
Subscription.modifierExtension	?! This element is a modifier element.	0..*	Extension	Extensions that cannot be ignored
Subscription.status	?! This element is a modifier element. Σ This element is included in summaries.	1..1	code	requested | active | error | off Binding: SubscriptionStatus (required): The status of a subscription.
Subscription.reason	Σ This element is included in summaries.	1..1	string	Description of why this subscription was created
Subscription.criteria	Σ This element is included in summaries. C	1..1	string	Rule for server push Constraints: ohh-subscription-criteria
Subscription.channel	Σ This element is included in summaries.	1..1	BackboneElement	The channel on which to report matches to the criteria
Subscription.channel.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored even if unrecognized
Subscription.channel.type	Σ This element is included in summaries.	1..1	code	rest-hook | websocket | email | sms | message Binding: SubscriptionChannelType (required): The type of method used to execute a subscription. Fixed Value: rest-hook (no extensions allowed)
Documentation for this format

Terminology Bindings

Path	Status	Usage	ValueSet	Version	Source
Subscription.status	Base	required	SubscriptionStatus	📍4.0.1	FHIR Std.
Subscription.channel.​type	Base	required	SubscriptionChannelType	📍4.0.1	FHIR Std.

Constraints

Id	Grade	Path(s)	Description	Expression
dom-2	error	Subscription	If the resource is contained in another resource, it SHALL NOT contain nested Resources	contained.contained.empty()
dom-3	error	Subscription	If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource	contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().as(canonical) | %resource.descendants().as(uri) | %resource.descendants().as(url))) or descendants().where(reference = '#').exists() or descendants().where(as(canonical) = '#').exists() or descendants().where(as(canonical) = '#').exists()).not()).trace('unmatched', id).empty()
dom-4	error	Subscription	If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated	contained.meta.versionId.empty() and contained.meta.lastUpdated.empty()
dom-5	error	Subscription	If a resource is contained in another resource, it SHALL NOT have a security label	contained.meta.security.empty()
dom-6	best practice	Subscription	A resource should have narrative for robust management	text.`div`.exists()
ele-1	error	**ALL** elements	All FHIR elements must have a @value or children	hasValue() or (children().count() > id.count())
ext-1	error	**ALL** extensions	Must have either extensions or value[x], not both	extension.exists() != value.exists()
ohh-subscription-criteria	error	Subscription.criteria	Criteria can only be on QuestionnaireResponse, PlanDefinition, CarePlan or Task	matches('^(QuestionnaireResponse|PlanDefinition|CarePlan|Task).*')

Snapshot View

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Subscription		0..*	Subscription	Server push subscription criteria
Subscription.id	Σ This element is included in summaries.	0..1	id	Logical id of this artifact
Subscription.meta	Σ This element is included in summaries.	0..1	Meta	Metadata about the resource
Subscription.implicitRules	?! This element is a modifier element. Σ This element is included in summaries.	0..1	uri	A set of rules under which this content was created
Subscription.language		0..1	code	Language of the resource content Binding: CommonLanguages (preferred): A human language. Additional Bindings Purpose AllLanguages Max Binding
Subscription.text		0..1	Narrative	Text summary of the resource, for human interpretation This profile does not constrain the narrative in regard to content, language, or traceability to data elements
Subscription.contained		0..*	Resource	Contained, inline Resources
Subscription.extension		0..*	Extension	Additional content defined by implementations
Subscription.modifierExtension	?! This element is a modifier element.	0..*	Extension	Extensions that cannot be ignored
Subscription.status	?! This element is a modifier element. Σ This element is included in summaries.	1..1	code	requested | active | error | off Binding: SubscriptionStatus (required): The status of a subscription.
Subscription.contact	Σ This element is included in summaries.	0..*	ContactPoint	Contact details for source (e.g. troubleshooting)
Subscription.end	Σ This element is included in summaries.	0..1	instant	When to automatically delete the subscription
Subscription.reason	Σ This element is included in summaries.	1..1	string	Description of why this subscription was created
Subscription.criteria	Σ This element is included in summaries. C	1..1	string	Rule for server push Constraints: ohh-subscription-criteria
Subscription.error	Σ This element is included in summaries.	0..1	string	Latest error note
Subscription.channel	Σ This element is included in summaries.	1..1	BackboneElement	The channel on which to report matches to the criteria
Subscription.channel.id		0..1	string	Unique id for inter-element referencing
Subscription.channel.extension		0..*	Extension	Additional content defined by implementations
Subscription.channel.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored even if unrecognized
Subscription.channel.type	Σ This element is included in summaries.	1..1	code	rest-hook | websocket | email | sms | message Binding: SubscriptionChannelType (required): The type of method used to execute a subscription. Fixed Value: rest-hook (no extensions allowed)
Subscription.channel.endpoint	Σ This element is included in summaries.	0..1	url	Where the channel points to
Subscription.channel.payload	Σ This element is included in summaries.	0..1	code	MIME type to send, or omit for no payload Binding: Mime Types (required): The mime type of an attachment. Any valid mime type is allowed.
Subscription.channel.header	Σ This element is included in summaries.	0..*	string	Usage depends on the channel type
Documentation for this format

Terminology Bindings

Path	Status	Usage	ValueSet	Version	Source
Subscription.language	Base	preferred	Common Languages	📍4.0.1	FHIR Std.
Subscription.status	Base	required	SubscriptionStatus	📍4.0.1	FHIR Std.
Subscription.channel.​type	Base	required	SubscriptionChannelType	📍4.0.1	FHIR Std.
Subscription.channel.​payload	Base	required	MimeType	📍4.0.1	FHIR Std.

Constraints

Id	Grade	Path(s)	Description	Expression
dom-2	error	Subscription	If the resource is contained in another resource, it SHALL NOT contain nested Resources	contained.contained.empty()
dom-3	error	Subscription	If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource	contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().as(canonical) | %resource.descendants().as(uri) | %resource.descendants().as(url))) or descendants().where(reference = '#').exists() or descendants().where(as(canonical) = '#').exists() or descendants().where(as(canonical) = '#').exists()).not()).trace('unmatched', id).empty()
dom-4	error	Subscription	If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated	contained.meta.versionId.empty() and contained.meta.lastUpdated.empty()
dom-5	error	Subscription	If a resource is contained in another resource, it SHALL NOT have a security label	contained.meta.security.empty()
dom-6	best practice	Subscription	A resource should have narrative for robust management	text.`div`.exists()
ele-1	error	**ALL** elements	All FHIR elements must have a @value or children	hasValue() or (children().count() > id.count())
ext-1	error	**ALL** extensions	Must have either extensions or value[x], not both	extension.exists() != value.exists()
ohh-subscription-criteria	error	Subscription.criteria	Criteria can only be on QuestionnaireResponse, PlanDefinition, CarePlan or Task	matches('^(QuestionnaireResponse|PlanDefinition|CarePlan|Task).*')

This structure is derived from Subscription

Summary

Fixed: 1 element

Creating a Subscription

To create a Subscription to get notified about changes you’ll need to have an endpoint/URL available that can handle the notification requests.

If you want subscriptions to only be valid until a specific time, you can specify the end value of a subscription. This can be helpful if you specify an authorization token that has a limited lifetime in the headers. Note that you should keep track of expired subscriptions yourself. We won’t create new subscriptions if they expire. No notifications will be sent for this subscription after the specified timestamp. The status of the subscription will then also change to off. You can extend a subscription, or replace an expiring token in the headers, by updating it, see Updating a Subscription.

When creating a Subscription, you can choose to also retrieve the content with the notification by setting the payload to one of the 2 allowed values [application/fhir+json, application/fhir+xml]. If you don’t want to receive the content, you’ll need to execute the request defined in the criteria to retrieve the items.

With Payload

If you have set the payload to one of the allowed values, we’ll send the notifications with the (related) content of the subscribed resource in a Bundle of type history.

Headers

If your server endpoint needs specific headers in the HTTP Post request, you can add them in the channel.header field. This can, for example, be used when the endpoint is secured with authentication. You can, for example, add an Authorization: Bearer <jwttoken> value to the headers. When the notification is posted, these headers will be added to the request.

Supported criteria

We currently support subscriptions on PlanDefinition, QuestionnaireResponse, CarePlan and Task:

PlanDefinition

You can register a Subscription on PlanDefinitions to receive notification when new programs for your client are published or if changes occur to a specific program by adding an _id query parameter to the criteria.

When the payload property has been set, the posted Bundle will contain the PlanDefinition that was changed/created.

QuestionnaireResponse

You can register a Subscription on QuestionnaireResponse to receive notification when new answers for a questionnaire have become available. The criteria determine which responses you are notified about:

based-on and based-on.instantiates-canonical cannot be combined in one Subscription.

When the payload property has been set, the posted Bundle will contain the QuestionnaireResponse (with encrypted values) and the Questionnaire that corresponds to this QuestionnaireResponse. If you created the Subscription via the FHIR Viewer Gateway, the gateway will handle decryption of the QuestionnaireReponse

You can additionally narrow the Subscription to patients that have an identifier in a specific system, see Filtering on patient identifier system.

CarePlan

You can register a Subscription on CarePlan to receive notification when a CarePlan is created or updated, or when a questionnaire that is part of the CarePlan has been filled out. The criteria determine which CarePlans you are notified about:

_id and instantiates-canonical cannot be combined in one Subscription.

You can additionally narrow the Subscription to patients that have an identifier in a specific system, see Filtering on patient identifier system.

When the payload property has been set, the posted Bundle will contain the CarePlan that was updated/created.

Task

You can register a Subscription on Task to receive a notification when a notification or call task or a questionnaire task of a CarePlan is created or changes. A notification is sent:

• when the task is created, for example when a CarePlan is created or when a reminder is scheduled after a questionnaire;
• when the start time of the task passes and its status changes from requested to ready, or to in-progress for a notification task. This notification is sent within about a minute after executionPeriod.start;
• when its status changes to completed, cancelled or failed, for example when Open Health Hub has sent a notification to the patient, a questionnaire has been filled out or a client has updated the status;
• when a completed, cancelled or failed notification is made active again;
• when its executionPeriod changes because the start of the CarePlan has been moved.

A notification that Open Health Hub sends to the patient starts and is completed at about the same moment, so you can receive an in-progress and a completed notification for it shortly after each other.

The criteria determine which tasks you are notified about:

• _id, based-on and based-on.instantiates-canonical cannot be combined in one Subscription. Each of them can be combined with code and status, each with one value.
• The code is PUSH_NOTIFICATION, CALL_PATIENT or complete-questionnaire, optionally with its system as in the Task.
• The status is one of requested, ready, in-progress, completed, cancelled or failed. It is matched with the status of the task at the moment of the change, so a task that is created before its start time has the status requested.
• To be notified on more than one code or status, create a Subscription per value.

You can additionally narrow the Subscription to patients that have an identifier in a specific system, see Filtering on patient identifier system.

You receive notifications for the tasks that you can read with a GET on Task.

When the payload property has been set, the posted Bundle will contain the Task that was created or changed.

Filtering on patient identifier system

On QuestionnaireResponse, CarePlan and Task subscriptions you can add a patient.identifier query parameter to only receive notifications for patients that have an identifier in a specific system. Use the token form with a system and an empty value, so <system>|. The | may be written literally or percent-encoded as %7C:

CarePlan?instantiates-canonical=3b47d913-03f7-41cb-a0ed-ca3a0a44f9b5&patient.identifier=urn:oid:2.16.840.1.113883.2.4.99|
QuestionnaireResponse?patient.identifier=urn:oid:2.16.840.1.113883.2.4.99%7C

A notification is only sent when the patient of the triggering resource has at least one identifier in that system; patients without one are skipped. Filtering on an identifier value is not supported, and neither is filtering on more than one system — create a Subscription per system. The parameter is not supported on PlanDefinition subscriptions, because those notifications are not about a single patient; using it there is rejected with an OperationOutcome on Subscription.criteria.

Receiving notifications

A notification is posted to the endpoint of the Subscription. Respond with a 2xx status within 60 seconds to confirm that you received it. When processing a notification takes longer, respond first and process it afterwards, for example by putting it in a queue.

An error response (4xx or 5xx), or no response within 60 seconds, means the notification failed. Failed notifications are sent again:

• When your endpoint can’t be reached or is temporarily unavailable, the notification is first sent again after a few seconds.
• A notification that still failed is retried every 5 minutes for as long as the Subscription is active. Retries stop when the Subscription expires or is deleted.

A retried notification contains the content of the resource at the time of the retry, not at the time of the first attempt. When a notification for a later change of the same resource is delivered first, the earlier failed notification is no longer retried, because you already received the latest content. Notifications for changes that follow each other quickly can still arrive in a different order.

You can receive the same notification more than once, for example when your endpoint processed it but responded too late. Make sure that processing a notification twice has no unwanted effects, for example by checking whether you already processed the same content for that resource.

Updating a Subscription

An existing Subscription can be updated with a PUT on Subscription/[id]. This can, for example, be used to change the endpoint, to replace an authorization token in the headers or to change the end date of the subscription. The time of the last update is returned in meta.lastUpdated, it is absent when the Subscription hasn’t been updated since it was created.

Preventing concurrent updates

Every Subscription has a version, which is returned in meta.versionId and in the ETag header when reading, creating or updating it. To prevent overwriting changes made in the meantime, send an If-Match header containing the current version, e.g. If-Match: W/"3". The update is then only executed when this version matches the current version of the Subscription. Without an If-Match header the update is always executed. Every successful update increases the version by one. A meta.versionId in the request body is ignored, only the If-Match header is used.

When the update is rejected because the Subscription has been changed in the meantime, retrieve the Subscription again, apply your change to the retrieved Subscription and send the update again with the new version. Don’t just repeat the update with the new version, as this would overwrite the other change.

The ETag can also be used with an If-None-Match header when reading a Subscription. The response will then be 304 Not Modified when the Subscription hasn’t changed. Older versions of a Subscription are not kept, so reading a specific version (_history) is not supported.

What can be updated

An update replaces the complete Subscription. Elements that are left out of the update are removed, e.g. leaving out channel.header removes all headers and leaving out end makes the subscription valid indefinitely. The easiest way to update a Subscription is to retrieve it, change the elements you want to change and send the complete Subscription back.

• channel.endpoint, channel.header, channel.payload, reason and end can be changed.
• The criteria can’t be changed. Create a new Subscription (and delete the old one) when you want to be notified about other resources.
• The status should be requested, active or off. The status of a Subscription is derived from its end, so it doesn’t change by an update. Use a DELETE to stop a subscription.
• The end should be in the future. An expired subscription becomes active again when its end is updated to a time in the future.
• If you created the Subscription via the FHIR Viewer Gateway, the gateway keeps handling the notifications for the subscription after an update. Leaving out the gateway endpoint extension keeps the current gateway, but the extension can’t be added to or changed in an existing Subscription.

Notifications sent after the update use the updated endpoint and headers. This also applies to notifications that failed before the update and are retried afterwards, see Receiving notifications.

Responses