System support for object groups
Rachid Guerraoui, Pascal Felber, Benoit Garbinato & Karim Mazouni
| Résumé |
This paper draws several observations from our experiences in
building support for object groups. These observations actually go
beyond our experiences and may apply to many other developments of
object based distributed systems. Our first experience aimed at
building support for Smalltalk object replication using the Isis
process group toolkit. It was quite easy to achieve group
transparency but we were confronted with a strong mismatch between
the rigidity of the process group model and the flexible nature of
object interactions. Consequently we decided to build our own
object oriented protocol framework, specifically dedicated to
support object groups (instead of using a process group toolkit).
We built our framework in such a way that basic distributed
protocols, such as failure detection and multicasts, are considered
as first class entities, directly accessible to the programmers. To
achieve flexible and dynamic protocol composition, we had to go
beyond inheritance and objectify distributed algorithms. Our second
experience consisted in building a CORBA service aimed at managing
group of objects written on different languages and running on
different platforms. This experience revealed a mismatch between
the asynchrony of group protocols and the synchrony of standard
CORBA interaction mechanisms, which limited the portability of our
CORBA object group service. We restricted the impact of this
mismatch by encapsulating asynchrony issues inside a specific
messaging sub-service. We dissect the cost of object group
transparency in our various implementations, and we point out the
recurrent sources of overheads, namely message indirection,
marshaling/unmarshaling and strong consistency. |
| Citation | R. Guerraoui, et al., "System support for object groups," Acm Sigplan Notices, vol. 33, p. 244-258, 1998. |
| Type | Article de périodique (Anglais) |
| Date de publication | 1998 |
| Nom du périodique | Acm Sigplan Notices |
| Volume | 33 |
| Numéro | 10 |
| Pages | 244-258 |