SAP products are built on a platform called Web Application Server (WebAS). WebAS is a very powerful and highly standardized platform. WebAS could be installed on a variety of hardware and could work with various databases. This gives IT department great flexibility in terms of SAP`s installation. WebAS supports popular programming language and protocols including Web Services, XML, HTML, ABAP, and Java.ABAP is SAP’s traditional programming language. Hence WebAS is very flexible in terms of its development capabilities as well.
SAP software uses a three-tiered architecture.
In a three-tiered architecture there are three nodes:
- Presentation Layer or Client
- Business Logic or Application Server
- Database Server
Various devices could be used to access SAP business software. For example: desktop, mobile devices, laptops, and so run. This device would be called a presentation layer. You might have to install a piece of software on these devices so that they could talk to the application server (computer running the actual SAP software). You could also use your web browser to access SAP application. Whatever the case may be, the front end device would communicate with the application server. The device would simply display you a presentation layer while the application is actually running on the application server. The device is also called a “client”.
The actual SAP software runs on an application server. Client node simply displays the image of the screen that is actually being produced on the application server. It is important to note the application server only runs SAP software. Data is not stored in application server
Data is stored on a separate machine called database server. Presentation layer communicates with application server to retrieve the screen image to be displayed to the user. Application server in turn communicates with the database server to write data to the database and to retrieve data from the database. The database server would be hosting a database management system like Oracle. Oracle is the most popular choice of database to be used with SAP software. Other databases could be used as well e.g. SQL Server (from Microsoft) and DB2 (form IBM).
Network is an important part of a three tiered architecture. The client computer would connect to the application server through internet, or company specific intranet, local area, network, dial up line etc. Similar media is used by application server to communicate with database server. This way user can run business application virtually from anywhere.
Three-tiered architecture provides scalability and flexibility. If overtime, load is increased on the application server, then another application server could be added. Or simply more memory or CPU could be added to the same application server without disturbing other nodes. Similarly database server could be upgraded without touching the other nodes. Also when it is time to upgrade the business logic to a newer version, only application server absorbs the new business logic patches.
SAP is SOA enabled. SOA (pronounced as so-uh) stands for Service-Oriented Architecture. SOA architecture is based on NetWeaver technology. Being SOA enabled means that SAP software support service calls. Any program (even external to SAP) can make a service call to SAP to retrieve some useful information or to register new information. For example let’s say you have developed an external website that needs to retrieve current pricing information from SAP software. Instead of retrieving information from the database (by writing SQL) your website will make a service all to SAP requesting prices on selected items. Also your website may make a service call to SAP to register a new customer. The information might arrive to your program responsible for generating website in an XML (Extensible Mark-up Language) format.XML is a popular choice of protocol for data exchange. You can then parse this data and display it to the website in any layout you like using HTML (Hypertext Mark-up Language). Websites are built using HTML language. This is the language that your browser can decode. SOA architecture brings flexibility to the table. It makes it easy for external applications to communicate with SAP.