ENTERPRISE SERVICES ARCHITECTURE

ENTERPRISE SERVICES ARCHITECTURE pronounce ESA

Designing an adaptable enterprise computing solution is now possible using ESA.

Using ESA, SAP R/3 and other legacy SAP solutions can be plugged in as application services.

SAP NetWeaver is a component of SAP software that provides the platform for integrating these application services.

By using NetWeaver you can adopt an Enterprise Services Architecture.

Strickly speaking Netweaver using four-tier architecture.

You can say that: ECA = Application talking amoung each other using services on a Four Tier Architecture

Enterprise Services Architecture

SAP is building is solution around a new model: Enterprise Services Architecture (ESA).

ESA involves various applications talking to each other via services.

Architecture

The three-tiered architecture divides the architecture into three layers:

* The user interface layer

* The business logic layer ("application" layer)

* The database layer
The 3 tier solution is more scalable.

Now upgrading application is easier as well. The application now resides one (or few) machine: middle tier, as oppose to hundreds of client PCs.

SAP engineers also abstracted the database layer. Many different databases are supported.

The client/server architecture was a two tier solution. The two tiers were: the Server computer and the Client PCs.

Later on SAP engineers constructed a solution that involved three tiers rather than two

A central computer hosts the database.

This computer is known as the database server.

The application server is responsible for the administrative functions including background processing and printing.

Multiple application servers can exist in an SAP three-tiered design.

This is not true for the database server, however.

There can be various computers fulfilling the role of presentation server.

These computers are also called front-end clients.

These computers display the SAP screens.

SAP graphical user interface (GUI), or SAP GUI is installed on these computers.

The four-tiered system enables simple browser-based access.

This laywer helps in reducing the expense associated with installing, patching, and upgrading the SAP GUI user interface across perhaps hundreds or thousands of desktops.

Also it helps to integrate web services into the overall architecture.

Four-tiered architectures

SAP introduced Four-tiered architectures when enterprise software vendors recognized the value that the Internet or company-internal intranets can provide to the end-users.

The fourth layer is called "accessibility tier" or "services tier".

This layer exists in between the application and presentation tiers.

SAP WebAS

WebAS is very flexible.

Due to this flexibility an orgranization can initially choose to deploy SAP system very similar to how they do business today, and then gradually evolve business model over time.

The SAP system has three tiers.

The presentation layer, application logic, and data management are logically separate from one another.

ECC (ERP Central Component) is built around a different type of architecture.

It uses SAP NetWeaver and Enterprise Services Architecture.

Client/Server Environment

SAP R/3 (old version) was using an architecture called client/server. The newer version of SAP R/3 is called ECC: ERP Central Component.



They can also be made to be physically separated.

In this way, a flexible system can be created.

Additional headroom can be easily added when required.

Most SAP components are built on a powerful platform called Web Application Server, or WebAS.

WebAS understand most popular computer languages including HTML, XML, Web Services, SAP ABAP/4, and Java

To store back end date, many database versions and releases are supported.

Client/server is of a few architectures available.

In a client/server environment, a client machine requests information, via network, from the supplying machine, known as the server.

A client machine could be an individual PC, workstation, mobile computing device, or even another computer system.