Like client/server, Middleware is another overused buzzword, but it is critical in the development of N-Tier client/server systems. Middleware by definition, sits between the client and the server. It converts data and allows very different systems to get along.
The increasingly rapid upward migration of companies to enterprise-wide computing has been made possible, in part, by the emergence of a generation of powerful, field-proven Middleware technologies.
Middleware begins with an API on the client that can invoke services remotely. It handles the transmission of the request and the resulting response, however it often doesn't provide an actual service such as an interface or server process.
Middleware categories include transaction processing (TP) monitors, Application Partitioning tools, database Middleware, remote procedure calls (RPCs), message-oriented Middleware (MOM), and object-request brokers (ORBs).
These Middleware solutions, often described generically as Transaction Process (TP) Monitors, provide the support needed for distributed transactional processing across networks running multiple machines and databases.
see [Application Partitioning],[Business Quality Messaging] or [Transaction Process Monitors (TP)] for details
Multitier database implementations provide an additional layer of security,
performance, and management for database administrators by providing mediated access to specific databases where caching or local business rules may be implemented as needed.
Objects and Brokers
The two basic types of database Middleware are native database Middleware and database-generic Middleware.
Native database Middleware is a proprietary access mechanism for a particular database server.
Database-generic Middleware, such as Microsoft's Open Database Connectivity (ODBC), enables applications and packages to communicate across different SQL dialects, network protocols, and native APIs, using common interfaces.
Although the database industry is standardizing database access, it's still a hodgepodge of proprietary access mechanisms. So hiding native database access behind layers of Middleware makes sense.
A recent trend which has enhanced the emergence of distributed computing has been the refinement of object-oriented, or object-broker multi-tiered architectures.
In an environment where change is the only constant, businesses are finding that
objects allow them to adapt more quickly and easily.
Object broker environments deliver end-results that are similar to the output of a traditional service provider arrangement. In the object broker world, however, the presentation layer instantiates objects of a special class, which in turn instantiates specific objects that provide the needed data result.
When connected to and used to manipulate a Relational Database Management System, the object broker environment promotes the seamless delivery of applications across enterprises with diverse platforms, operating systems and programming languages.
Today's computing environment contains more challenges than ever. Object technology is exciting and proving effective at meeting these challenges.
With its new approach to building software, it is helping organizations to better address the pressures of a dynamic and highly competitive marketplace.
(See Object Technology) for more details.
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