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Efficient Message Dispatching in Distributed Environments

IP.com Disclosure Number: IPCOM000110663D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 83K

Publishing Venue

IBM

Related People

West, AM: AUTHOR

Abstract

When implementing object-oriented messages in a distributed system the normal method is to use a proxy or surrogate object which is using the remote object. The proxy object is a shadow of the real object which forwards the message to the real object elsewhere in the system. The drawbacks of using proxy objects is that they impose unnecessary knowledge requirements on the user of the remote object, having to populate client systems with these proxy objects, and they also interpose an unnecessary level of indirection and complication between the user of the objects.

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Efficient Message Dispatching in Distributed Environments

       When implementing object-oriented messages in a
distributed system the normal method is to use a proxy or surrogate
object which is using the remote object.  The proxy object is a
shadow of the real object which forwards the message to the real
object elsewhere in the system.  The drawbacks of using proxy objects
is that they impose unnecessary knowledge requirements on the user of
the remote object, having to populate client systems with these proxy
objects, and they also interpose an unnecessary level of indirection
and complication between the user of the objects.

      A solution to the above problems is to provide a special
addressing scheme for objects.  The scheme caters for three kinds of
objects 1) objects based on the native operating environment
messaging system, 2) local objects as defined in PMPLUS [*], and 3)
remote objects.  Remote objects are ones on a different system and
potentially running in a different environment, to one on which the
message send is executed.  The scheme is potentially implementable on
a variety of hardware and operating system environments (IBM Products
AIX*; 370: MVS, VM, AIX on RISC System/6000* and RT*; X86: Windows,
OS/2*.)  It removes the need for proxy objects on all machines which
require to use them.  Also a name resolution protocol is employed to
locate classes on a network.

      The scheme uses the least significant bits of an object handle
as flags, as follows:
00        Native system object
01        Local object
10        Remote object

      The message send function would then process a send request as
follows:
1.  Isolate the two low-order bits.
2.  Shift left two bits (multiply by four).
3.  Go via branch table to appropriate handler.

      When the object is a system or local object the processing
would be...