B
Front-End and Back-End Integration

The requirements for front-office and back-office integration are fundamentally different and, as a result, they require fundamentally different integration approaches. This appendix contains:

• Front-End Integration

• Back-End Integration

Front-End Integration

In this implementation, middleware or a similar integration solution intercepts interactions between applications. The middleware acts as a middle tier application server: transparently marshaling, managing, and directing interapplication requests and responses. Typically, the requesting application waits while the middleware requests services of another application.

Figure B-1 Front-End Integration

Front-end integration solutions generally display some, or all, of these characteristics:

• Interaction between the integration layer and the applications is:
  • Synchronous, or simulates synchronous processing

  • Two-way communication based on a service request model

• Transactions processed are of short duration.

• The application (user) is not aware of using the services of multiple disparate applications.

• Middleware behaves like a midtier application server: marshaling, managing, and directing requests and responses and managing transactional and recovery issues.

Front-end integration has both advantages and disadvantages.

Advantages

• You can develop a number of presentation layers for different user, customer, and supply channels.

• All presentation layers share the same services, thus ensuring consistent interactions regardless of channel.

• Each presentation layer requires only one signon to access all required functionality.

Drawbacks

Applications must meet these criteria to participate in the interactions:

• All functionality must be offered through a service-based API.

• All business and data logic must be separate from the presentation layer.

• The transaction/commit model must act as a resource manager in the chosen multiphase commit processing.

• Few legacy and currently available ERP/CRM packages meet these criteria, so you probably must develop a custom application.

• The presentation layer of packaged applications is unlikely to be usable. This may lead to difficulties in providing support, lengthy implementation time, and so on.

• It is difficult to manage a development and testing environment because of the need for a complex architecture, the lack of suitable strong tools, and the dependence on program-oriented delivery.

Back-End Integration

In this implementation, users interact with only one application at a time in a manner determined by their user roles.The application notifies other applications as necessary of the significant aspects of the user interaction. Application-to-application interactions can be based on further sequential notifications.

Figure B-2 Back-end integration

Back-end integration solutions display some or all of these characteristics:

• Interaction between the integration layer and the applications is:
  • Predominantly asynchronous

  • One-way communication

• Service-request and event-notification models are both used.

• Business process definitions closely mirror the business, and consequently transactions take a long time.

• The user interacts with a single application or with a small number of applications.

• The integration solution acts transparently as a sophisticated distribution and synchronizing agent.

Advantages

• The presentation layer interface to the applications need not employ the same architecture as the applications.

• You can use the prebuilt presentation layer delivered with packaged applications.

• The business and data logic in an application need not be separate from the delivered presentation layer.

• It is easy to manage the development and testing environments because asynchronous breakpoints provide natural testing points.

• Graphical tools are provided to ease development.

Drawbacks

• Each application has a different look and feel and a different signon, which makes applications appear to be only loosely integrated.

• The user interface is narrowly constrained, thus restricting users who act in multiple and diverse roles.