Mission Operations Reference Model. Draft ... - CCSDS

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DRAFT RECOMMENDED PRACTICE FOR MISSION OPERATIONS REFERENCE MODEL4.6 TRANSPORT LAYER ARCHITECTUREThe Transport layer is responsible for taking the abstract message from the MAL andtransmitting it to the destination:Access ControlAccess Control ServiceDigitalSigningTransport ServiceTransport Layer«delegate»Encoding ComponentTransport AdapterMessage Transport MiddlewareTransport Specific PortFigure 4-12: Transport Layer ArchitectureThere are several aspects to the component that are shown in the above figure. It is notintended that these aspects be actual components of an implementation; however, it isexpected that they will be represented in behaviour.a) The Transport Adaptor is responsible for managing the flow of messages between theinternal components of the Transport component.b) The Encoding Component is responsible for the conversion from the abstract messageformat of the MAL into the physical representation used by that transport. It has anassociation with the Digital Signing aspect of the Access Control component if this isapplicable for the security deployment in use.c) Digital Signing function may not actually reside in the Access Control component butis shown like this because the two functions are related.d) The Message Transport Middleware is the aspect that is responsible for the actualtransmission of the encoded message to the destination.<strong>CCSDS</strong> 520.1-R-1 Page 4-15 October 2009
DRAFT RECOMMENDED PRACTICE FOR MISSION OPERATIONS REFERENCE MODELNOTES1 Splitting of an abstract message into multiple fragments is a Transport layer issue andis not shown in this document.2 If multiple separate technologies are to be used by the Transport layer to transmit thefragments, then the coordinate of these separate technologies is an implementationdetail and is not shown here.3 Recombination of the message fragments is a responsibility of the Transport layer.4.6.1 MESSAGE SENDING SEQUENCEFigure 4-13 shows the message sending sequence for the Transport layer. It includes the errorcases as alternative fragments.MAL Transport Layer Access ControlDestination EntityTransmit messagePre-check messagealt Message check failureReturn transport erroralt If message from a ProviderTransmit error message to transaction sourceEncode messageDigitally sign messagealt Security check failureReturn transport errorEncrypt messageOpen connection to destinationalt Connection failureReturn transport errorTransmit messagealt Message transport failureReturn transport errorReturn okFigure 4-13: Transport Layer Sending Sequence<strong>CCSDS</strong> 520.1-R-1 Page 4-16 October 2009
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Mission Operations Reference Model. Draft ... - CCSDS

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