Middleware Technologies compiled by Thomas M Cosley Introduction

Middleware Technologies compiled by: Thomas M. Cosley

Introduction 4 Middleware is connectivity software that provides a mechanism for processes to interact with other processes running on multiple networked machines. 4 Middleware Application Programming Interfaces provide a more functional set of capabilities than the OS and network services provide on their own.

Middleware Architecture Application API’s Middleware (Distributed Systems Services) Platform Interface Platform – OS Network Interface

Types of Middleware 4 There are four basic types of middleware – Transaction Processing Monitor (TP) – Remote Procedure Call (RPC) – Message-Oriented Middleware (MOM) – Object Request Broker (ORB)

Transaction Processing (TP) 4 TP can provide the following – control transaction applications – provide business logic/rules – database updates

Transaction Processing Architecture Processing Routines Transaction Requests Client TP Monitor

Remote Procedure Call (RPC) 4 RPC is a client/server mechanism that allows the program to be distributed across multiple platforms. 4 RPC’s reduce the complexity of a system that spans multiple operating systems and network protocols by hiding OS and network interface details from the programmer.

Remote Procedure Call (cont’d) 4 RPC’s are usually implemented by: – proprietary products – proprietary development tools that create client server stubs 4 Most RPC implementations use a synchronous (call/wait) protocol to communicate between client and server.

RPC Architecture Client App RPC STUB T R A N S P O R T N E T W O R K Application Specific procedure invocations and returns N E T W O R K T R A N S P O R T Server App RPC STUB

Message Oriented Middleware (MOM) 4 Message-oriented middleware – functionality similar to RPC – provides asynchronous communication between client and server applications by queueing messages temporarily when one or the other is busy or not connected.

MOM Architecture Client App MOM With message queue T R A N S P O R T N E T W O R K Application specific proprietary messages N E T W O R K T R A N S P O R T MOM With message queue Server App

Object Request Broker (ORB) 4 ORB’s overcome; machine, software and vendors are no boundaries for the ORB. 4 Major functionality includes: – interface definition – location and activation of remote objects – communication between clients and objects

ORB Architecture Request Service activate Service Establish connection Client communicate Remote Service (object)