 |
 |
 |
|
| Three Cheers for Three Tiers by Angie Arnold and Paul Miller Today's communications business environment is one of the most rapidly and dynamically evolving industries in the world. For that reason, speed and flexibility are important characteristics of successful service providers. In fact, a key differentiator among providers is the ability to rapidly deploy and configure their operational support systems (OSS) to continuously meet the demands of customers, technologies and the marketplace. The trick, of course, is to do so cost-effectively. The underlying architecture of a service provider's OSS is a determining factor in how well its organization can react to change. A two-tier architecture, for instance, has inherent scalability and interoperability problems. It cannot effectively distribute the processing power between the client and the application server, resulting in a "fat" client or server. While this is acceptable in a relatively homogeneous environment with fairly static business rules, it becomes a limitation when that environment changes and grows and resources cannot be flexibly allocated. Two-tier structures also entail heavy network traffic since there is no middle tier to handle multiple server requests and complex data access. As the business environment grows, so too do development efforts, migration costs and maintenance workloads.
A three-tier architecture, on the other hand, is a flexible and scalable way of organizing distributed client-server systems. It clearly separates client programs from data sources, allowing the programs to be maintained more easily. This enables providers to cost-effectively match their functional and processing resources to the needs of their entire organization. The three-tier architecture model is comprised of three major application layers that support the following key functions:
This three-tier architecture delivers four key benefits to service providers: enhanced operational efficiency, ensured data integrity, increased scalability and reduced deployment costs. Enhanced operational efficiencyA three-tier architecture enhances operational efficiency in several significant ways. First, it allows localization of servers to points of need; service providers can devote a single server to a specific area of service, thereby guaranteeing adequate capacity for transaction-heavy processes. Second, it enables providers to distribute discrete portions of the application across multiple servers based on their organization's individual business needs, processing requirements and geographical hierarchy. Finally, three-tier architecture minimizes software distribution if only server-side portions of the application are touched during development; this feature reduces or eliminates costly upgrades related to client-side portions of applications resting on hundreds, if not thousands, of remote machines. Ensured data integrity A three-tier architecture eliminates the time-consuming system errors caused by fraudulent data and reduces the risk of data corruption and/or loss that can result in uncontrolled system outages or failures. It does this by handling changes to data at centralized control points, ensuring that all user and system requests are properly formatted when submitted to the database. Changes are written once and placed on the middle tier to be available throughout the system. Database restructuring, upgrades, migration and other changes can be performed without stopping or altering the client programs. Furthermore, concurrency controls preserve data integrity when multiple application clients simultaneously perform requests against one or more servers. Increased scalability By separating code into "client" and "server" code, a three-tier architecture increases the scalability of service providers' applications. They can deploy an application's components and data on one or more servers based on current organizational and geographical processing needs. Then they can reconfigure and re-deploy their system resources as the application's user base grows and data and transaction volumes increase. In short, service providers that choose an OSS with a three-tier architecture can be confident that it will readily scale with their business. Reduced deployment costsA three-tier architecture separates business logic from data layers within the application, thereby giving mission-critical front- and back-office systems (such as billing and service activation) direct access to published interface definitions. The ability to expose both business and data rules to external applications greatly reduces the time and cost required for initial implementation and for subsequent upgrades to the core OSS and/or to various external systems connected to it.
Once the server-side applications have been completed, the development time for client-side applications is greatly reduced. This architecture eases future modification to interface points. They can be isolated when change is required so as not to affect other internal or external application functions, thus reducing the risk of system failure or a complete outage. The bottom line The benefits of a three-tier architecture combine to decrease service providers' costs and increase their revenues. It decreases costs by maximizing data integrity, reducing wide-scale deployment of client-side application components, and allowing increased access at points. This architecture increases providers' revenues by enabling more users to access a wider variety and larger numbers of local and remote servers, facilitating rapid implementation with other OSSs, and eliminating labor-intensive overhead associated with administration of multiple servers.
From Current OSS, Winter 2001, Vol. 2, No. 2. Published by Eftia OSS Solutions. |