18-04-2013, 02:36 PM
Processes and threads
Processes.ppt (Size: 189 KB / Downloads: 59)
Process forms a building block in distributed systems
Processes granularity is not sufficient for distributed systems
Multiple threads make easier to build distributed applications
Thread Implementation
userlevel library: switching in a few instructions, no change in memory maps etc. but a blocking system call blocks the entire processO.S. kernel level : no problem with blocking system call but every thread operation has to be carried out by the kernel, so switching contest similar to process
Object Server
An object server doesn’t provide a
real specific service
Services are provided by objects
One can add or modify services
adding or modifying objects
Different invocation approach can be used
to invoke an object in an object server
(activation policy)
An object adapter (or o. wrapper) is a
mechanism to group objects per policy
An obj. adapter controls one or more objs.
If a server supports objs with different
activation policy, several adapters reside on
the same server