Abbreviations

Results for area 3.15 Publication and subscription web services

term
service – WS-PubSub
definition

a Service is a process running on a server computer that responds to requests of a particular type

NOTE Some types of service may initiate requests in their own right. SIRI is made up of a number of different types of SIRI functional Service.

term
WS-resource – WS-PubSub
definition

a resource such as a Subscription that is used to support a stateful pattern of interaction must have certain characteristics, such as an endpoint reference, with which Consumer and Notification Producer can agree to refer to the resource, and an address to which notification message can be sent

NOTE 1 to entry WS-PubSub indicates what these characteristics and equivalent elements are present in SIRI: note however that for some SIRI implementations, some resource properties may be specified statically in the configuration, rather than being specified dynamically on each individual message.

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term
endpoint address – WS-PubSub
definition

the Address part of Endpoint Reference, specified as (the URI to send a message to) and Endpoint Reference Properties, that identify stateful resources

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term
endpoint reference – WS-PubSub
definition

a web service endpoint is a referenceable, entity, or processor resource to which Web Service messages can be targeted. Endpoint references convey the information needed to identify and reference a Web service.

Endpoint references are used to provide addresses for individual messages sent to and from Web Services, both synchronously and asynchronously. An endpoint reference includes an Address (the URI to which to send a message) and also Endpoint Reference Properties, that identify stateful resources, such as subscriptions. They may also indicate a Port and Processing Policies. WS-PubSub and the other web service standards require the separation of the endpoint references from their bindings to a given transport protocol, such as SOAP.

In SIRI, each Participant is an endpoint for each of its roles in message exchange, i.e. Subscriber, Producer and Consumer. A Subscription Reference is an Endpoint property and is typically made up of two parts: (i) a Participant Reference, which may be specified in the configuration to indicate the Control Centre, and is not necessarily repeated explicitly on individual messages, and (ii) the Subscription Identifier, which is a serial number for an individual subscription that is unique within the SIRI Functional Service and Participant Reference.

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term
publish-subscribe – WS-PubSub
definition

a pattern of interaction between a Client (as Subscriber and Consumer) and Server (as Notification Producer) involving the sending of an initial Subscription and the subsequent asynchronous receipt of one or more Notification Messages that contain a payload of information. The Subscription has a Lease, which defines it duration.

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term
participant – SIRI
definition

a system that participates in the exchange of messages using the SIRI protocols

NOTE A Participant has a Participant Reference, used to identify the participant in message exchanges, and also used to provide a general purpose namespace to scope arbitrary identifiers of model elements such as line and vehicle identifiers. In SIRI Consumers and Notification Producers (i.e. Control Centres) are Participants.

term
participant reference – SIRI
definition

unique identifier of a Control Centre or other type of Service Participant

NOTE The reference is bilaterally agreed between participating systems, and will typically be unique for a region of a country within which systems need to communicate. The Participant Reference is used to scope other data identifiers within each bilateral date reference agreement.

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term
consumer – WS-PubSub
definition

an entity that receives Notification messages from a Producer as a result of a previous Subscription made to a Service

NOTE In SIRI, in order to manage recovery, a Consumer must know the Subscriber which asked for its subscriptions.

term
subscriber – WS-PubSub
definition

an entity that acts as a Service Requestor, sending a Subscription Request on behalf of a Consumer to a Notification Producer. The Consumer entity will usually be the same entity as the Subscriber, but may also be a separate entity.

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term
subscriber channel – SIRI
definition

a SIRI Notification Producer mediates the flow of notifications it processes so as to reduce the amount of data traffic to a subscriber. All SIRI subscriptions for a Subscriber are automatically assigned to a Subscriber Channel. The subscriptions in a channel are mediated collectively; if a Situation affects more than one subscription within a channel, only a single notification is sent to the subscriber. The resulting delivery contains all updates for all subscriptions in the channel. There is at least one subscriber channel per Subscriber; some implementations may allow more than one channel for a given subscriber.

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subscriber reference – SIRI
definition

a Participant Reference i.e. identifier of a Participant acting as a Subscriber: provides a unique scope for the Message Reference

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subscription manager – WS-PubSub
definition

a Subscription Manager is a service that allows a Service requestor to create and manipulate Subscription Resources. A Subscription Manager is subordinate to the Notification Producer and may be implemented by the Notification Producer service, or separately as desired. In SIRI only limited capabilities to manage subscriptions are provided.

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term
subscription reference – WS-PubSub
definition

the identifier issued to identify a Subscription, and subsequently used to refer to it in further exchanges within the Publish/Subscribe stateful resource pattern

NOTE In SIRI, the Subscription Reference comprises two parts: the Subscriber Reference (i.e. the Participant Code of the subscriber), and the Subscription Identifier: unique within the scope of a Participant Reference. Subscriber References are issued by a Subscriber in SIRI, not the Producer.

Formally in WS-PubSub, a subscription reference is a WS resource returned in a Subscription Response containing the address of the Subscription Manager, and the Subscription Identifier. In SIRI the address of the Subscription Manager is obtained indirectly.

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term
subscription request – WS-PubSub
definition
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term
service subscription request – SIRI
definition

a service Subscription Request specifies the specific SIRI Functional Service for which the Subscription Request is made

NOTE SIRI Functional Service Subscription Requests have the form XxxSubscriptionRequest and are always embedded in a Subscription Request.

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term
subscription response – WS-PubSub
definition

a Delivery from the Server to the Client, returned in response to a Subscription Request; either confirming the creation or other change to a Subscription, or giving an Error Condition

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subscription termination – WS-PubSub
definition

a Request from the Client to the Server to close a Subscription

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lease – WS-PubSub
definition

the allowed duration of a Subscription

NOTE In SIRI, leases are specified by an Initial Termination Time and cannot be negotiated or renewed.

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term
producer – WS-PubSub
definition

an entity that sends Notification messages to a Consumer as a result of a previous Subscription made to it for a Functional Service. Events that give rise to Notification messages are sent to the Producer by a Publisher entity.

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term
message reference – WS-PubSub
definition

the identifier issued to identify an individual request within a conversation, and subsequently used to refer to the request in further exchanges within a stateful resource pattern, such as Publish/Subscribe, or Fetched Delivery

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term
data ready notification – SIRI
definition

the first message of the Fetched Delivery sequence: it informs the Consumer that the Notification Producer Service has updated data that is now ready to fetch using a Data Supply message.

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term
delivery – SIRI
definition

a message or message sequence sent from the Producer to the Consumer to return payload content, either in immediate response to a Request, or sent asynchronously when a Notification Producer determines that the conditions of a Subscription are satisfied

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direct delivery – SIRI
definition

a one step Delivery pattern in which the notification and payload is sent as a single message from the Producer to the Consumer

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fetched delivery – SIRI
definition

a two step Delivery in which first a Data Ready message is sent from the Producer service to the Consumer to notify the Consumer that data is ready, and then secondly the Consumer fetches the data by sending a Data Supply request to the Producer Service, which then finally sends a Data Supply Response message with the actual payload

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multipart despatch – SIRI
definition

delivery of large packet of data by breaking it down into two or more Delivery messages, chained together by a ‘MoreData’ flag

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term
publisher – WS-PubSub
definition

an entity that processes events in the data feeds and sends Notification messages to a Producer for brokering and distribution to Consumers

NOTE The Producer may carry out additional mediation such as filtering or data transformation. The use of a Notification Producer is transparent in SIRI.

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term
publisher registration – WS-PubSub
definition

a Publisher Registration represents the relationship between a Publisher and a Notification Broker, an optional WS-PubSub intermediary that can be introduced to delegate the distribution of Notification Messages to one or more distinct entities that act as Notification Producers

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notification – WS-PubSub
definition

the act of transmitting a Notification Message to a Notification Consumer. Notifications are sent from the Publisher to the Producer and then from the Producer to the Consumer. The direct unmediated forwarding of notifications from the Publisher by the Producer without filtering or transformation is termed ‘unbrokered’ notification. SIRI requires the mediation of messages by the Producer.

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notification broker – WS-PubSub
definition

a separate intermediary entity that may be used to distribute the Notification Messages produced by a Publisher entity to one or more Notification Producer services

NOTE 1 to entry This allows the decoupling of Publisher and Producer roles if desired. A Notification Broker may also provide specific services such as Access Control.

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term
notification consumer – WS-PubSub
definition

a Client that receives Notification Messages from a Notification Producer

NOTE The role may be performed by the same or a different entity as that of the Subscriber who created the Subscription which requested the sending of the Notification Messages in the first place.

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term
notification producer – WS-PubSub
definition

a Service that implements the distribution of Notification messages to satisfy Subscriptions.

NOTE The Notification Messages themselves are generated by a Publisher (and may be routed to the Notification Producer via a Notification Broker). A Notification Producer maintains a list of Subscription resources and uses the Topic Filters of the individual Subscriptions to match the Notification Messages with the Subscribers’ interests. If it identifies a match, it issues a notification to the Notification Consumer associated with the Subscription.

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term
topic – WS-PubSub
definition

a concept used by a Notification Producer to categorise Notification Messages to decide which Subscribers should be sent a Notification

NOTE 1 to entry A Subscriber specifies which Topics it is interested in as part of its Subscription Request.

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term
sensitivity threshold – SIRI
definition

a term in a Subscription Policy specifying of the degree of change that is permitted in the values of certain quantitative Topic data elements or other Subscription Policy values before a further update Delivery should be provided by the Server to its Subscribers. Also known as ‘hysteresis’.

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