NHS Digital FHIR Implementation Guide

FHIR Messaging

This is the FHIR version of traditional messaging. It differs from FHIR RESTful in that all the resources are sent to the recipient in one interaction. This is particularly useful between organisations where all the FHIR resources can be sent in one interaction.

The general FHIR principle that resources MUST be self contained still applies. FHIR Messaging should not be used to send highly coupled complex interactions, the message SHOULD be easily converted into resource based interactions. A FHIR Message bundle is not a storage based concept, it should be expected that all the resources in the Bundle can be processed individually. Should this be required consider using

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FHIR Messaging should only be used for defined interactions/messages, ad-hoc interactions/collections should use transactions

E.g. in the diagram below a prescription consists of one Patient resource and two MedicationRequests. Using FHIR Messaging all the resources are sent within one FHIR Message Bundle. Doing the same with FHIR RESTful would require at least three transactions (possibly more depending on the handling of the Patient resource).

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FHIR Message reduces the number of transactions and decouples the sending organisation from local rules. All the resources are handled in a single package and the receiving organisation can handle them according to local procedures.

FHIR Messaging is very similar to the messaging used in HL7 v2 and HL7 v3 (/ITK), hence the term traditional messaging.

FHIR Bundle (type=message)

Profile url
`https://fhir.nhs.uk/StructureDefinition/NHSDigital-Bundle-FHIRMessage`

Bundle	I		Bundle	There are no (further) constraints on this element Element id Bundle Short description Contains a collection of resources Definition A container for a collection of resources. Data type Bundle Constraints bdl-7: FullUrl must be unique in a bundle, or else entries with the same fullUrl must have different meta.versionId (except in history bundles) `(type = 'history') or entry.where(fullUrl.exists()).select(fullUrl&resource.meta.versionId).isDistinct()` bdl-9: A document must have an identifier with a system and a value `type = 'document' implies (identifier.system.exists() and identifier.value.exists())` bdl-3: entry.request mandatory for batch/transaction/history, otherwise prohibited `entry.all(request.exists() = (%resource.type = 'batch' or %resource.type = 'transaction' or %resource.type = 'history'))` bdl-4: entry.response mandatory for batch-response/transaction-response/history, otherwise prohibited `entry.all(response.exists() = (%resource.type = 'batch-response' or %resource.type = 'transaction-response' or %resource.type = 'history'))` bdl-12: A message must have a MessageHeader as the first resource `type = 'message' implies entry.first().resource.is(MessageHeader)` bdl-1: total only when a search or history `total.empty() or (type = 'searchset') or (type = 'history')` bdl-2: entry.search only when a search `entry.search.empty() or (type = 'searchset')` bdl-11: A document must have a Composition as the first resource `type = 'document' implies entry.first().resource.is(Composition)` bdl-10: A document must have a date `type = 'document' implies (timestamp.hasValue())` Mappings rim: Entity. Role, or Act v2: N/A rim: N/A cda: ClinicalDocument, if bundle.type = document
id	Σ	0..1	string	There are no (further) constraints on this element Element id Bundle.id Short description Logical id of this artifact Definition The logical id of the resource, as used in the URL for the resource. Once assigned, this value never changes. Comments The only time that a resource does not have an id is when it is being submitted to the server using a create operation. Data type string
meta	Σ	0..1	Meta	There are no (further) constraints on this element Element id Bundle.meta Short description Metadata about the resource Definition The metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content might not always be associated with version changes to the resource. Data type Meta Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a rim: N/A
implicitRules	Σ ?!	0..1	uri	There are no (further) constraints on this element Element id Bundle.implicitRules Short description A set of rules under which this content was created Definition A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc. Comments Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of it's narrative along with other profiles, value sets, etc. Data type uri Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
language		0..1	codeBinding	There are no (further) constraints on this element Element id Bundle.language Short description Language of the resource content Definition The base language in which the resource is written. Comments Language is provided to support indexing and accessibility (typically, services such as text to speech use the language tag). The html language tag in the narrative applies to the narrative. The language tag on the resource may be used to specify the language of other presentations generated from the data in the resource. Not all the content has to be in the base language. The Resource.language should not be assumed to apply to the narrative automatically. If a language is specified, it should it also be specified on the div element in the html (see rules in HTML5 for information about the relationship between xml:lang and the html lang attribute). Data type code Binding A human language. CommonLanguages (preferred) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
identifier	S Σ	1..1	Identifier	There are no (further) constraints on this element Element id Bundle.identifier Short description Persistent identifier for the bundle Definition A persistent identifier for the bundle that won't change as a bundle is copied from server to server. Comments Persistent identity generally only matters for batches of type Document, Message, and Collection. It would not normally be populated for search and history results and servers ignore Bundle.identifier when processing batches and transactions. For Documents the .identifier SHALL be populated such that the .identifier is globally unique. Data type Identifier Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: CX / EI (occasionally, more often EI maps to a resource id or a URL) rim: II - The Identifier class is a little looser than the v3 type II because it allows URIs as well as registered OIDs or GUIDs. Also maps to Role[classCode=IDENT] servd: Identifier w5: FiveWs.identifier cda: ClinicalDocument.id
id		0..1	string	There are no (further) constraints on this element Element id Bundle.identifier.id Short description Unique id for inter-element referencing Definition Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. Data type string Mappings rim: n/a
extension	I	0..*	Extension	There are no (further) constraints on this element Element id Bundle.identifier.extension Short description Additional content defined by implementations Alternate names extensions, user content Definition May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Sliced: Unordered, Open, by url(Value) Extensions are always sliced by (at least) url Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
use	Σ ?!	0..1	codeBinding	There are no (further) constraints on this element Element id Bundle.identifier.use Short description usual \| official \| temp \| secondary \| old (If known) Definition The purpose of this identifier. Requirements Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers. Comments Applications can assume that an identifier is permanent unless it explicitly says that it is temporary. Data type code Binding Identifies the purpose for this identifier, if known . IdentifierUse (required) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: N/A rim: Role.code or implied by context
type	Σ	0..1	CodeableConceptBinding	There are no (further) constraints on this element Element id Bundle.identifier.type Short description Description of identifier Definition A coded type for the identifier that can be used to determine which identifier to use for a specific purpose. Requirements Allows users to make use of identifiers when the identifier system is not known. Comments This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage. Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type. Data type CodeableConcept Binding A coded type for an identifier that can be used to determine which identifier to use for a specific purpose. Identifier Type Codes (extensible) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: CE/CNE/CWE rim: CD orim: fhir:CodeableConcept rdfs:subClassOf dt:CD v2: CX.5 rim: Role.code or implied by context
system	S Σ	1..1	uri	There are no (further) constraints on this element Element id Bundle.identifier.system Short description The namespace for the identifier value Definition Establishes the namespace for the value - that is, a URL that describes a set values that are unique. Requirements There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers. Comments Identifier.system is always case sensitive. Data type uri Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Examples General http://www.acme.com/identifiers/patient Mappings rim: n/a v2: CX.4 / EI-2-4 rim: II.root or Role.id.root servd: ./IdentifierType
value	S Σ	1..1	string	There are no (further) constraints on this element Element id Bundle.identifier.value Short description The value that is unique Definition The portion of the identifier typically relevant to the user and which is unique within the context of the system. Comments If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the Rendered Value extension. Identifier.value is to be treated as case sensitive unless knowledge of the Identifier.system allows the processer to be confident that non-case-sensitive processing is safe. Data type string Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Examples General 123456 Mappings rim: n/a v2: CX.1 / EI.1 rim: II.extension or II.root if system indicates OID or GUID (Or Role.id.extension or root) servd: ./Value
period	Σ I	0..1	Period	There are no (further) constraints on this element Element id Bundle.identifier.period Short description Time period when id is/was valid for use Definition Time period during which identifier is/was valid for use. Comments A Period specifies a range of time; the context of use will specify whether the entire range applies (e.g. "the patient was an inpatient of the hospital for this time range") or one value from the range applies (e.g. "give to the patient between these two times"). Period is not used for a duration (a measure of elapsed time). See Duration. Data type Period Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` per-1: If present, start SHALL have a lower value than end `start.hasValue().not() or end.hasValue().not() or (start <= end)` Mappings rim: n/a v2: DR rim: IVL<TS>[lowClosed="true" and highClosed="true"] or URG<TS>[lowClosed="true" and highClosed="true"] v2: CX.7 + CX.8 rim: Role.effectiveTime or implied by context servd: ./StartDate and ./EndDate
assigner	Σ I	0..1	Reference(Organization)	There are no (further) constraints on this element Element id Bundle.identifier.assigner Short description Organization that issued id (may be just text) Definition Organization that issued/manages the identifier. Comments The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization. Data type Reference(Organization) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ref-1: SHALL have a contained resource if a local reference is provided `reference.startsWith('#').not() or (reference.substring(1).trace('url') in %rootResource.contained.id.trace('ids'))` Mappings rim: n/a rim: The target of a resource reference is a RIM entry point (Act, Role, or Entity) v2: CX.4 / (CX.4,CX.9,CX.10) rim: II.assigningAuthorityName but note that this is an improper use by the definition of the field. Also Role.scoper servd: ./IdentifierIssuingAuthority
type	S Σ	1..1	codeBindingFixed Value	Element id Bundle.type Short description document \| message \| transaction \| transaction-response \| batch \| batch-response \| history \| searchset \| collection Definition Indicates the purpose of this bundle - how it is intended to be used. Comments It's possible to use a bundle for other purposes (e.g. a document can be accepted as a transaction). This is primarily defined so that there can be specific rules for some of the bundle types. Data type code Binding Indicates the purpose of a bundle - how it is intended to be used. BundleType (required) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Fixed value message Mappings rim: n/a w5: FiveWs.class
timestamp	S Σ	1..1	instant	There are no (further) constraints on this element Element id Bundle.timestamp Short description When the bundle was assembled Definition The date/time that the bundle was assembled - i.e. when the resources were placed in the bundle. Comments For many bundles, the timestamp is equal to .meta.lastUpdated, because they are not stored (e.g. search results). When a bundle is placed in a persistent store, .meta.lastUpdated will be usually be changed by the server. When the bundle is a message, a middleware agent altering the message (even if not stored) SHOULD update .meta.lastUpdated. .timestamp is used to track the original time of the Bundle, and SHOULD be populated. Usage: document : the date the document was created. Note: the composition may predate the document, or be associated with multiple documents. The date of the composition - the authoring time - may be earlier than the document assembly time message : the date that the content of the message was assembled. This date is not changed by middleware engines unless they add additional data that changes the meaning of the time of the message history : the date that the history was assembled. This time would be used as the _since time to ask for subsequent updates searchset : the time that the search set was assembled. Note that different pages MAY have different timestamps but need not. Having different timestamps does not imply that subsequent pages will represent or include changes made since the initial query transaction \| transaction-response \| batch \| batch-response \| collection : no particular assigned meaning The timestamp value should be greater than the lastUpdated and other timestamps in the resources in the bundle, and it should be equal or earlier than the .meta.lastUpdated on the Bundle itself. Data type instant Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a w5: FiveWs.init cda: ClinicalDocument.effectiveTime
total	Σ I	0..1	unsignedInt	There are no (further) constraints on this element Element id Bundle.total Short description If search, the total number of matches Definition If a set of search matches, this is the total number of entries of type 'match' across all pages in the search. It does not include search.mode = 'include' or 'outcome' entries and it does not provide a count of the number of entries in the Bundle. Comments Only used if the bundle is a search result set. The total does not include resources such as OperationOutcome and included resources, only the total number of matching resources. Data type unsignedInt Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
link	Σ	0..0	BackboneElement	There are no (further) constraints on this element Element id Bundle.link Short description Links related to this Bundle Definition A series of links that provide context to this bundle. Comments Both Bundle.link and Bundle.entry.link are defined to support providing additional context when Bundles are used (e.g. HATEOAS). Bundle.entry.link corresponds to links found in the HTTP header if the resource in the entry was read directly. This specification defines some specific uses of Bundle.link for searching and paging, but no specific uses for Bundle.entry.link, and no defined function in a transaction - the meaning is implementation specific. Data type BackboneElement Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
entry	S Σ I	1..*	BackboneElement	Element id Bundle.entry Short description Entry in the bundle - will have a resource or information Definition An entry in a bundle resource - will either contain a resource or information about a resource (transactions and history only). Data type BackboneElement Sliced: Unordered, Open, by resource.resourceType(Value) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` bdl-8: fullUrl cannot be a version specific reference `fullUrl.contains('/_history/').not()` bdl-5: must be a resource unless there's a request or response `resource.exists() or request.exists() or response.exists()` Mappings rim: n/a
(All Slices)				There are no (further) constraints on this element
id		0..1	string	There are no (further) constraints on this element Element id Bundle.entry.id Short description Unique id for inter-element referencing Definition Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. Data type string Mappings rim: n/a
extension	I	0..*	Extension	There are no (further) constraints on this element Element id Bundle.entry.extension Short description Additional content defined by implementations Alternate names extensions, user content Definition May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Sliced: Unordered, Open, by url(Value) Extensions are always sliced by (at least) url Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
modifierExtension	Σ ?! I	0..*	Extension	There are no (further) constraints on this element Element id Bundle.entry.modifierExtension Short description Extensions that cannot be ignored even if unrecognized Alternate names extensions, user content, modifiers Definition May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself). Requirements Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
link	Σ	0..0	see (link)	There are no (further) constraints on this element Element id Bundle.entry.link Short description Links related to this entry Definition A series of links that provide context to this entry.
fullUrl	Σ	1..1	uri	There are no (further) constraints on this element Element id Bundle.entry.fullUrl Short description URI for resource (Absolute URL server address or URI for UUID/OID) Definition The Absolute URL for the resource. The fullUrl SHALL NOT disagree with the id in the resource - i.e. if the fullUrl is not a urn:uuid, the URL shall be version-independent URL consistent with the Resource.id. The fullUrl is a version independent reference to the resource. The fullUrl element SHALL have a value except that: fullUrl can be empty on a POST (although it does not need to when specifying a temporary id for reference in the bundle) Results from operations might involve resources that are not identified. Comments fullUrl might not be unique in the context of a resource. Note that since FHIR resources do not need to be served through the FHIR API, the fullURL might be a URN or an absolute URL that does not end with the logical id of the resource (Resource.id). However, but if the fullUrl does look like a RESTful server URL (e.g. meets the regex, then the 'id' portion of the fullUrl SHALL end with the Resource.id. Note that the fullUrl is not the same as the canonical URL - it's an absolute url for an endpoint serving the resource (these will happen to have the same value on the canonical server for the resource with the canonical URL). Data type uri Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
resource	Σ	0..1	Resource	There are no (further) constraints on this element Element id Bundle.entry.resource Short description A resource in the bundle Definition The Resource for the entry. The purpose/meaning of the resource is determined by the Bundle.type. Data type Resource Mappings rim: Entity. Role, or Act
search	Σ I	0..1	BackboneElement	There are no (further) constraints on this element Element id Bundle.entry.search Short description Search related information Definition Information about the search process that lead to the creation of this entry. Data type BackboneElement Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
id		0..1	string	There are no (further) constraints on this element Element id Bundle.entry.search.id Short description Unique id for inter-element referencing Definition Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. Data type string Mappings rim: n/a
extension	I	0..*	Extension	There are no (further) constraints on this element Element id Bundle.entry.search.extension Short description Additional content defined by implementations Alternate names extensions, user content Definition May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Sliced: Unordered, Open, by url(Value) Extensions are always sliced by (at least) url Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
modifierExtension	Σ ?! I	0..*	Extension	There are no (further) constraints on this element Element id Bundle.entry.search.modifierExtension Short description Extensions that cannot be ignored even if unrecognized Alternate names extensions, user content, modifiers Definition May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself). Requirements Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
mode	Σ	0..1	codeBinding	There are no (further) constraints on this element Element id Bundle.entry.search.mode Short description match \| include \| outcome - why this is in the result set Definition Why this entry is in the result set - whether it's included as a match or because of an _include requirement, or to convey information or warning information about the search process. Comments There is only one mode. In some corner cases, a resource may be included because it is both a match and an include. In these circumstances, 'match' takes precedence. Data type code Binding Why an entry is in the result set - whether it's included as a match or because of an _include requirement, or to convey information or warning information about the search process. SearchEntryMode (required) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
score	Σ	0..1	decimal	There are no (further) constraints on this element Element id Bundle.entry.search.score Short description Search ranking (between 0 and 1) Definition When searching, the server's search ranking score for the entry. Comments Servers are not required to return a ranking score. 1 is most relevant, and 0 is least relevant. Often, search results are sorted by score, but the client may specify a different sort order. See Patient Match for the EMPI search which relates to this element. Data type decimal Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
request	Σ I	0..1	BackboneElement	There are no (further) constraints on this element Element id Bundle.entry.request Short description Additional execution information (transaction/batch/history) Definition Additional information about how this entry should be processed as part of a transaction or batch. For history, it shows how the entry was processed to create the version contained in the entry. Data type BackboneElement Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
id		0..1	string	There are no (further) constraints on this element Element id Bundle.entry.request.id Short description Unique id for inter-element referencing Definition Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. Data type string Mappings rim: n/a
extension	I	0..*	Extension	There are no (further) constraints on this element Element id Bundle.entry.request.extension Short description Additional content defined by implementations Alternate names extensions, user content Definition May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Sliced: Unordered, Open, by url(Value) Extensions are always sliced by (at least) url Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
modifierExtension	Σ ?! I	0..*	Extension	There are no (further) constraints on this element Element id Bundle.entry.request.modifierExtension Short description Extensions that cannot be ignored even if unrecognized Alternate names extensions, user content, modifiers Definition May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself). Requirements Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
method	Σ	1..1	codeBinding	There are no (further) constraints on this element Element id Bundle.entry.request.method Short description GET \| HEAD \| POST \| PUT \| DELETE \| PATCH Definition In a transaction or batch, this is the HTTP action to be executed for this entry. In a history bundle, this indicates the HTTP action that occurred. Comments Note that FHIR strings SHALL NOT exceed 1MB in size Data type code Binding HTTP verbs (in the HTTP command line). See HTTP rfc for details. HTTPVerb (required) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
url	Σ	1..1	uri	There are no (further) constraints on this element Element id Bundle.entry.request.url Short description URL for HTTP equivalent of this entry Definition The URL for this entry, relative to the root (the address to which the request is posted). Comments E.g. for a Patient Create, the method would be "POST" and the URL would be "Patient". For a Patient Update, the method would be PUT and the URL would be "Patient/[id]". Data type uri Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
ifNoneMatch	Σ	0..1	string	There are no (further) constraints on this element Element id Bundle.entry.request.ifNoneMatch Short description For managing cache currency Definition If the ETag values match, return a 304 Not Modified status. See the API documentation for "Conditional Read". Comments Note that FHIR strings SHALL NOT exceed 1MB in size Data type string Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
ifModifiedSince	Σ	0..1	instant	There are no (further) constraints on this element Element id Bundle.entry.request.ifModifiedSince Short description For managing cache currency Definition Only perform the operation if the last updated date matches. See the API documentation for "Conditional Read". Comments Note: This is intended for where precisely observed times are required, typically system logs etc., and not human-reported times - for them, see date and dateTime (which can be as precise as instant, but is not required to be) below. Time zone is always required Data type instant Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
ifMatch	Σ	0..1	string	There are no (further) constraints on this element Element id Bundle.entry.request.ifMatch Short description For managing update contention Definition Only perform the operation if the Etag value matches. For more information, see the API section "Managing Resource Contention". Comments Note that FHIR strings SHALL NOT exceed 1MB in size Data type string Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
ifNoneExist	Σ	0..1	string	There are no (further) constraints on this element Element id Bundle.entry.request.ifNoneExist Short description For conditional creates Definition Instruct the server not to perform the create if a specified resource already exists. For further information, see the API documentation for "Conditional Create". This is just the query portion of the URL - what follows the "?" (not including the "?"). Comments Note that FHIR strings SHALL NOT exceed 1MB in size Data type string Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
response	Σ I	0..1	BackboneElement	There are no (further) constraints on this element Element id Bundle.entry.response Short description Results of execution (transaction/batch/history) Definition Indicates the results of processing the corresponding 'request' entry in the batch or transaction being responded to or what the results of an operation where when returning history. Data type BackboneElement Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
id		0..1	string	There are no (further) constraints on this element Element id Bundle.entry.response.id Short description Unique id for inter-element referencing Definition Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. Data type string Mappings rim: n/a
extension	I	0..*	Extension	There are no (further) constraints on this element Element id Bundle.entry.response.extension Short description Additional content defined by implementations Alternate names extensions, user content Definition May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Sliced: Unordered, Open, by url(Value) Extensions are always sliced by (at least) url Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
modifierExtension	Σ ?! I	0..*	Extension	There are no (further) constraints on this element Element id Bundle.entry.response.modifierExtension Short description Extensions that cannot be ignored even if unrecognized Alternate names extensions, user content, modifiers Definition May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself). Requirements Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
status	Σ	1..1	string	There are no (further) constraints on this element Element id Bundle.entry.response.status Short description Status response code (text optional) Definition The status code returned by processing this entry. The status SHALL start with a 3 digit HTTP code (e.g. 404) and may contain the standard HTTP description associated with the status code. Comments Note that FHIR strings SHALL NOT exceed 1MB in size Data type string Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
location	Σ	0..1	uri	There are no (further) constraints on this element Element id Bundle.entry.response.location Short description The location (if the operation returns a location) Definition The location header created by processing this operation, populated if the operation returns a location. Comments see http://en.wikipedia.org/wiki/Uniform_resource_identifier Data type uri Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
etag	Σ	0..1	string	There are no (further) constraints on this element Element id Bundle.entry.response.etag Short description The Etag for the resource (if relevant) Definition The Etag for the resource, if the operation for the entry produced a versioned resource (see Resource Metadata and Versioning and Managing Resource Contention). Comments Etags match the Resource.meta.versionId. The ETag has to match the version id in the header if a resource is included. Data type string Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
lastModified	Σ	0..1	instant	There are no (further) constraints on this element Element id Bundle.entry.response.lastModified Short description Server's date time modified Definition The date/time that the resource was modified on the server. Comments This has to match the same time in the meta header (meta.lastUpdated) if a resource is included. Data type instant Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
outcome	Σ	0..1	Resource	There are no (further) constraints on this element Element id Bundle.entry.response.outcome Short description OperationOutcome with hints and warnings (for batch/transaction) Definition An OperationOutcome containing hints and warnings produced as part of processing this entry in a batch or transaction. Comments For a POST/PUT operation, this is the equivalent outcome that would be returned for prefer = operationoutcome - except that the resource is always returned whether or not the outcome is returned. This outcome is not used for error responses in batch/transaction, only for hints and warnings. In a batch operation, the error will be in Bundle.entry.response, and for transaction, there will be a single OperationOutcome instead of a bundle in the case of an error. Data type Resource Mappings rim: Entity. Role, or Act
messageHeader	S Σ I	1..*	BackboneElement	There are no (further) constraints on this element Element id Bundle.entry:messageHeader Short description Entry in the bundle - will have a resource or information Definition An entry in a bundle resource - will either contain a resource or information about a resource (transactions and history only). Data type BackboneElement Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` bdl-8: fullUrl cannot be a version specific reference `fullUrl.contains('/_history/').not()` bdl-5: must be a resource unless there's a request or response `resource.exists() or request.exists() or response.exists()` Mappings rim: n/a
id		0..1	string	There are no (further) constraints on this element Element id Bundle.entry:messageHeader.id Short description Unique id for inter-element referencing Definition Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. Data type string Mappings rim: n/a
extension	I	0..*	Extension	There are no (further) constraints on this element Element id Bundle.entry:messageHeader.extension Short description Additional content defined by implementations Alternate names extensions, user content Definition May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Sliced: Unordered, Open, by url(Value) Extensions are always sliced by (at least) url Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
modifierExtension	Σ ?! I	0..*	Extension	There are no (further) constraints on this element Element id Bundle.entry:messageHeader.modifierExtension Short description Extensions that cannot be ignored even if unrecognized Alternate names extensions, user content, modifiers Definition May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself). Requirements Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
link	Σ	0..*	see (link)	There are no (further) constraints on this element Element id Bundle.entry:messageHeader.link Short description Links related to this entry Definition A series of links that provide context to this entry.
fullUrl	Σ	0..1	uri	There are no (further) constraints on this element Element id Bundle.entry:messageHeader.fullUrl Short description URI for resource (Absolute URL server address or URI for UUID/OID) Definition The Absolute URL for the resource. The fullUrl SHALL NOT disagree with the id in the resource - i.e. if the fullUrl is not a urn:uuid, the URL shall be version-independent URL consistent with the Resource.id. The fullUrl is a version independent reference to the resource. The fullUrl element SHALL have a value except that: fullUrl can be empty on a POST (although it does not need to when specifying a temporary id for reference in the bundle) Results from operations might involve resources that are not identified. Comments fullUrl might not be unique in the context of a resource. Note that since FHIR resources do not need to be served through the FHIR API, the fullURL might be a URN or an absolute URL that does not end with the logical id of the resource (Resource.id). However, but if the fullUrl does look like a RESTful server URL (e.g. meets the regex, then the 'id' portion of the fullUrl SHALL end with the Resource.id. Note that the fullUrl is not the same as the canonical URL - it's an absolute url for an endpoint serving the resource (these will happen to have the same value on the canonical server for the resource with the canonical URL). Data type uri Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
resource	S Σ	0..1	NHSDigitalMessageHeader	Element id Bundle.entry:messageHeader.resource Short description A resource in the bundle Definition The Resource for the entry. The purpose/meaning of the resource is determined by the Bundle.type. Data type NHSDigitalMessageHeader Mappings rim: Entity. Role, or Act
search	Σ I	0..0	BackboneElement	There are no (further) constraints on this element Element id Bundle.entry:messageHeader.search Short description Search related information Definition Information about the search process that lead to the creation of this entry. Data type BackboneElement Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
request	Σ I	0..0	BackboneElement	There are no (further) constraints on this element Element id Bundle.entry:messageHeader.request Short description Additional execution information (transaction/batch/history) Definition Additional information about how this entry should be processed as part of a transaction or batch. For history, it shows how the entry was processed to create the version contained in the entry. Data type BackboneElement Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
response	Σ I	0..0	BackboneElement	There are no (further) constraints on this element Element id Bundle.entry:messageHeader.response Short description Results of execution (transaction/batch/history) Definition Indicates the results of processing the corresponding 'request' entry in the batch or transaction being responded to or what the results of an operation where when returning history. Data type BackboneElement Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a
signature	Σ	0..1	Signature	There are no (further) constraints on this element Element id Bundle.signature Short description Digital Signature Definition Digital Signature - base64 encoded. XML-DSig or a JWT. Requirements A Signature holds an electronic representation of a signature and its supporting context in a FHIR accessible form. The signature may either be a cryptographic type (XML DigSig or a JWS), which is able to provide non-repudiation proof, or it may be a graphical image that represents a signature or a signature process. This element allows capturing signatures on documents, messages, transactions or even search responses, to support content-authentication, non-repudiation or other business cases. This is primarily relevant where the bundle may travel through multiple hops or via other mechanisms where HTTPS non-repudiation is insufficient. Comments The signature could be created by the "author" of the bundle or by the originating device. Requirements around inclusion of a signature, verification of signatures and treatment of signed/non-signed bundles is implementation-environment specific. Data type Signature Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a rim: N/A

This message consists of a Bundle identified by the type "message", with the first resource in the bundle being a MessageHeader resource. The MessageHeader resource has a code - the message event - that identifies the nature of the request message, and it also carries additional request metadata. The other resources in the bundle depend on the type of the request.

For example a dispense-notification message will be a FHIR Bundle consisting of

one MessageHeader resource with an eventCoding dispense-notification
one to four MedicationDispense resources
one (optional) Patient resource.

Example dispense-notifications can be found in the NHS Digital Medicines Guide Examples

These Bundles are send to a $process-message operation, e.g.

POST baseUrl/$process-message

In the example above we stated rules for the dispense-notification message, these will be contained in a FHIR MessageDefinition and the message definition for this is https://fhir.nhs.uk/MessageDefinition/dispense-notification

{
    "resourceType": "MessageDefinition",
    "id": "bf729ea8-280b-4109-b2f5-02ce8e51d870",
    "url": "https://fhir.nhs.uk/MessageDefinition/dispense-notification",
    "identifier":  [
        {
            "system": "https://tools.ietf.org/html/rfc4122",
            "value": "bf729ea8-280b-4109-b2f5-02ce8e51d870"
        }
    ],
    "version": "1.0.0",
    "name": "NHSDigitalDispenseNotification",
    "title": "Pharmacy/Treatment Dispense",
    "status": "active",
    "date": "2020-10-02",
    "eventCoding": {
        "system": "https://fhir.nhs.uk/CodeSystem/message-event",
        "code": "dispense-notification",
        "display": "Dispense Notification"
    },
    "description": "Notification of dispensed medication",
    "category": "notification",
    "focus":  [
        {
            "code": "MedicationDispense",
            "profile": "https://fhir.nhs.uk/StructureDefinition/NHSDigital-MedicationDispense-Message",
            "min": 1,
            "max": "*"
        }
    ]
}

fhir-message-bundle

Some of the key points are:

element eventCoding This is the code that identifies the MessageDefinition and will match the eventingCode in the dispense-notification FHIR Message
element focus This lists the principal resources; in the example this is FHIR MedicationDispense resources which follows the NHSDigital-MedicationDispense profile. One and up to four resources can be supplied.
Patient resource is not in the focus section. The rule that a Patient resource is required is contained in the FHIR MedicationDispense profile.
MessageHeader resource is not in the focus section. It is mandatory in all FHIR Messages.

The FHIR MessageHeader contains the message metadata only and is designed to support message handling without having to process the full message. The use of FHIR MessageHeader with NHSDigital API's is discussed in

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. Note this FHIR R4 NHSDigital-MessageHeader is designed to handle all message types and contains rules from both previous MessageHeaders used in Transfer of Care (point to point messages) and National Event Messaging System (pub/sub messages).