- Object Services -- These are
domain-independent interfaces that are used by many distributed object
programs. For example, a service providing for the discovery of other
available services is almost always necessary regardless of the
application domain. Two examples of Object Services that fulfill this
role are:
- The Naming Service -- which allows clients to find
objects based on names;
- The Trading Service -- which allows clients
to find objects based on their properties.
There are also Object Service specifications for lifecycle management,
security, transactions, and event notification, as well as many others
[OMG:95b].
- Common Facilities -- Like Object Service interfaces,
these interfaces are also horizontally-oriented, but unlike Object
Services they are oriented towards end-user applications. An example
of such a facility is the Distributed Document Component
Facility (DDCF), a compound document Common Facility based on
OpenDoc. DDCF allows for the presentation and interchange of objects
based on a document model, for example, facilitating the linking of a
spreadsheet object into a report document.
- Domain Interfaces -- These interfaces fill roles similar
to Object Services and Common Facilities but are oriented towards
specific application domains. For example, one of the first OMG RFPs
issued for Domain Interfaces is for Product Data Management (PDM)
Enablers for the manufacturing domain. Other OMG RFPs will soon be
issued in the telecommunications, medical, and financial domains.
- Application Interfaces - These are
interfaces developed specifically for a given application. Because
they are application-specific, and because the OMG does not develop
applications (only specifications), these interfaces are not
standardized. However, if over time it appears that certain broadly
useful services emerge out of a particular application domain, they
might become candidates for future OMG standardization.
slide: Services