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CCSDS Message Bus Comparison. Shames, Barkley, Burleigh, Cooper, Haddow 28 Oct 2010. Intent of these materials. Present current descriptions of the four current standards that define and/or use message bus specifications Identify their specific features and interfaces
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CCSDS Message BusComparison Shames, Barkley, Burleigh, Cooper, Haddow 28 Oct 2010
Intent of these materials • Present current descriptions of the four current standards that define and/or use message bus specifications • Identify their specific features and interfaces • Compare the features and describe them in the context of the standard ISO Stack • Provide the basis for analysis of overlaps and harmonization
SM&C Message Abstraction Layer (MAL) • Message layer BB (interoperable only in combination with a data mapping and technology binding), generalized message structures, numerous interaction patterns (client/server and message bus), abstract service interface (and separate API spec), extensible message structure framework, transport agnostic (uses underlying message bus, JMS, AMQP, DDS, AMS)
SM&C MAL Protocol Stack SM&C Client/Server Application MAL API MAL Interaction Patterns SM&C Message encoding layer Transport adapter Message bus (JMS, AMQP, DDS, AMS)
SM&C MAL Message population stages SM&C Message encoding layer Populate MAL Message Body Populate MAL Message Header Encode to Message Bus format
Service Management (SM) • Specific Service (BB) for service management domain, application service entity behavior and document exchange protocol, specific set of client/server message interchange patterns, service message bindings to XML, transport agnostic (SMTP & HTTP/SOAP bindings to date)
SM Operation Procedures, Document Exchange Protocol, and Underlying Communication Service, Fig 3-1
Information Services Architecture (ISA) • Reference Model (MB) & Service Binding (BB) (Draft WB now) defines Registry service, service interface, a few specific message exchange patterns, specific service messages and structures, reusable/extensible information framework, it is data transport agnostic, using HTTP, JMS, and other methods
Representing the Information Service Architecture (ISA) Logical Stack • a layered view of the CCSDS-related services abstracting out the messaging middleware, from the information infrastructure allows us to understand the overlaps • CCSDS is involved in the development of standards at each of these levels • standards efforts should fit together and CCSDS should be mindful when standards effort cross multiple boundaries in the architectural model to ensure interoperability remains as a critical architectural tenet Messaging Middleware MAL / AMS HTTP / JMS Network Protocols / Physical Layer
AMS • AMS – BB, interoperable protocol specification (PDU, state machines) for generalized distributed messaging over long haul and short haul links, several supported interaction modes (client/server and message bus), & abstract AMS service interface, no specific message content specifications • AMS is a message bus system comprising three Application Layer protocols • Application AMS (AAMS) protocol conveys published application data over a variety of transport protocols • Meta-AMS (MAMS) protocol conveys AMS auto-configuration metadata - enabling AAMS traffic flow - over one of those transport protocols • Remote AMS (RAMS) protocol encapsulates AAMS messages in an underlying delay-tolerant protocol (notionally, but not necessarily, the DTN Bundle Protocol) for propagation across space links. • So AAMS is typically a TCP or UDP application, MAMS is usually a UDP application, and RAMS is a BP application.
Alignment with ISO MAL AMS SM ISA Application Presentation Session [Middleware] Transport Network Data Link Physical
SM&C MAL Protocol Stack Client Application Provider Application SM&C MAL SM&C MAL Message bus
MAL Message definition • Definition of the message body structure is static and is specified as part of a service definition. • The message encoding is agreed before hand and is an aspect of the deployment • The population of the message header is something that is performed at runtime.
ISA Notional Layers • Application – These are clients that leverage and use services and standard models. They include domain specific models necessary for interoperability. • Application Services – These are CCSDS domain specific services which are deployed into a SOA-style deployment. These include domain specific models necessary for interoperability. • Infrastructure Services – These are standard information services and models which support discovery and deployment of application services, information management services, etc. • Messaging Services – This is the messaging layer which identifies protocols and message structure necessary for applications to be deployed into a distributed service architecture. • Network Layer – This is the communication layer. Construction of higher order messaging and information/infrastructure services should be built on top of this layer.