Connectivity Framework Annex A: Assessment Template: DDS
A. 6.4 Functional Viewpoint A. 6.4.1 Core Framework Layer Functions
Data Resource Model
( Section 4.1.1)
ID & Addressing( Section 4.1.2)
Data Type System( Section 4.1.3)
Data Resource Lifecycle( CRUD)( Section 4.1.4)
State Management( Section 4.1.5)
Publish-Subscribe( Section 4.1.6)
Request-Reply( Section 4.1.7)
Discovery( Section 4.1.8)
Does it provide a data resource model? Summarize the salient aspects.
Yes, DDS provides a flexible resource model. User-defined data types define the structure of data objects. A DDS-Topic is a named collection of data objects that all have the same data type. Topics are user defined, and there can be any number of them.
Does it provide a way to identifying and addressing data objects? Summarize the identification and addressing scheme.
Yes, DDS provides a flexible user defined scheme for identifying and addressing data objects. A user can mark certain fields of the data type as“ key” fields— those are used to identify and address the data objects with a DDS-Topic. A data object is uniquely addressed by a domain id( which identifies the data space), the topic name within the data space and the key fields within that topic. Does it provide a data type system? Summarize the salient aspects.
Yes, DDS provides a very flexible data type system, analogous to that of a modern programming languages such as C, C ++, Java and. NET. The DDS-XTypes v1.1 specification defines extensible and mutable data types that can evolve over a system’ s lifecycle. Data types may be defined in a programming language neutral manner, such as Interface Definition Language( IDL) or XML.
Does it provide a means of managing a data object’ s lifecycle? Summarize the salient aspects.
Yes, DDS provides a means to manage the full data object lifecycle, including operations to create, read, update and delete data objects.
Does it provide a means to manage the recent history of data objects? Summarize the salient aspects.
Yes, DDS provides a rich set of QoS policies to manage the recent history of data objects. This includes caching user defined history of data objects independently at DDS- DataReaders and DDS-DataWriters, delivering historical data for late joiners, and caching the state in the data space, using the DDS-Persistence Service( an optional part of the DDS specification).
Does it provide a means to publish and subscribe the state of data objects? Summarize the salient aspects.
Yes, the fundamental interaction pattern is publish / subscribe. DDS-DataWriters are used to publish update to data objects; DDDS-DataReaders are used to subscribe to data object updates.
Does it provide a means to request the state of data objects? Summarize the salient aspects.
Yes, DDS provides a means to request the state of data object and receive appropriate response( s) via a published design pattern. The DDS-RPC v1.0( 2015) specification formalizes the design pattern and defines a distributed services framework providing language-independent service definition and service / remote procedure invocation using DDS. It supports automatic discovery, synchronous and asynchronous invocations and QoS. Does it provide a means to discover the data objects? Summarize the salient aspects.
Yes, DDS provides a means to discover the DDS-DomainParticipants, DDS-DataWriters, and DDS-DataReaders, and the DDS-Topics in a data space. Discovery is automatic and continuous as applications come and go. An application can access the discovery data simply by subscribing to pre-defined built-in discovery topics.
IIC: PUB: G5: V1.0: PB: 20170228- 66-