ISO IEC 14752 pdf download – Information technology — Open Distributed Processing — Protocol support for computational interactions

ISO IEC 14752 pdf download – Information technology — Open Distributed Processing — Protocol support for computational interactions
ln Figure 1, it should be noted that the computational and basic engineering objects are just corresponding views of thesame thing. There is no implication that one is contained in the other although other basic engineering objects maycorrespond to the same computational object (see 10.2 of ITU-T Rec.X.903 | ISO/IEC 10746-3).Similarly, thecomputational binding and the engineering binding are different views of the same thing.
The hierarchical ordering of the channel objects and of their liaisons in Figure 1 represents the static position when theliaisons are complete and are supporting a particular instance of a computational interaction.The hierarchy should not betaken as implying restrictions on when the liaisons are established or how the channel objects interact duringestablishment or other liaison management. Establishment of the various liaisons may involve interaction between any ofthe channel objects in a given node. Other engineering objects may also be involved, in some cases causing protocolexchanges at the interworking reference point. Liaison management, including establishment, may also use other pathsthan the one being managed. Establishment of any of the liaisons in Figure l can take place at an earlier epoch, or can beoverlapped with the establishment of the other liaisons. Where recovery of failed bindings is supported,theestablishment of a replacement channel may involve the establishment of new liaisons (to the same or different channelobjects) or the modification of the surviving liaisons.
For a particular protocol, a single event at the interworking reference point may carry semantics from several of theliaisons.This is termed “piggy-backing”.
The stub，binder and protocol liaisons can be established independently of the support of a single instance of acomputational interaction. These liaisons can be:
1)established prior to any specific computational interaction;
2)used for interactions between a number of different computational objects; and
3) used for an indefinite number of computational interactions, either consecutively or concurrently.
The stub, binder and protocol liaisons can also be transient, with the duration of the shared context between peer channelobjects being limited to the support of a single computational interaction.
NOTE-For cxample, a server-side object could maintain the state that supports a liaison only from the recipt of a request to theissue of the reply.
6.3Facilities of the GIF
As stated above,the GlF defines a set of facilities，each comprising a number of service primitives which arefunctionally related.Each facility is primarily the concern of one kind of engineering object.
The basic interworking facility supports the liaison of the basic engineering objects. It includes service primitiveswhich have a direct correspondence with the signals which model the computational operations.This facility is supportedby all protocols that support computational operations.
The access facility supports access transparency and is primarily the concern of the stub objects. The primitives concernthe negotiation of the representation of data to be transmitted via the channel.
The location facility supports location transparency and is primarily the concern of the binder objects. It includes serviceprimitives that allow a client-side protocol object to ask a server-side protocol object if it is an appropriate destination foraccess to a particular basic engineering object, and to allow a server-side protocol object to propose some other server-side.The use of this facility can be combined with the basic interworking facility to allow a server-side, where the client-side “expected” the target basic engineering object to be, to propose an alternative server-side. This allows a limitedequivalent of relocation transparency.
The association management facility defines service primitives that manage associations – liaisons between protocolobjects.An association has an existence independent of a particular instance of a computational interaction (see 8.2).
6.4Computational operations and signals
The RM-ODP introduces the concept of signal to express the semantics of more abstract interactions. A signal is atomicand localised at a reference point,and represents the initiation or completion at that reference point of some moreabstract distributed interaction. Thus an announcement can be delimited by two signals, representing its initiation at areference point in the sending system and its delivery at a reference point in the receiving system. Similarly， aninterrogation can be delimited by two pairs of signals.