SAP R/3 is the former name of the enterprise resource planning software produced by SAP AG. It is an enterprise-wide information system designed to coordinate all the resources, information, and activities needed to complete business processes such as order fulfillment or billing.
History of SAP R/3 
The first version of SAP's flagship enterprise software was a financial Accounting system named R/1 called as YSR. This was replaced by R/2 at the end of the 1970s. SAP R/2 was in a mainframe based business application software suite that was very successful in the 1980s and early 1990s. It was particularly popular with large multinational European companies who required soft-real-time business applications, with multi-currency and multi-language capabilities built in. With the advent of distributed client–server computing SAP AG brought out a client–server version of the software called SAP R/3 (The "R" was for "Real-time data processing" and 3 was for 3-tier). This new architecture is compatible with multiple platforms and operating systems, such as Microsoft Windows or UNIX. This opened up SAP to a whole new customer base.
SAP R/3 was officially launched on 6 July 1992. It was renamed SAP ERP and later again renamed SAP ECC (ERP Central Component). SAP came to dominate the large business applications market over the next 10 years. SAP ECC 5.0 ERP is the successor of SAP R/3 4.70. The newest version of the suite is SAP ECC 7.0.
- SAP R/3 Release 1.0A Release Date 6 July 1992
- SAP R/3 Release 2.0 / 2.1 Released 1993
- SAP R/3 Release 3.0 / 3.1 Released 1995
- SAP R/3 Release 4.0B Release Date June 1998
- SAP R/3 Release 4.5B Release Date March 1999
- SAP R/3 Release 4.6A Release Date 1999
- SAP R/3 Release 4.6B Release Date Dec 1999
- SAP R/3 Release 4.6C Release Date April 2001
- SAP R/3 Enterprise Release 4.70 Release Date March- Dec 2003
- SAP R/3 Enterprise Edition 4.7
- SAP R/3 Enterprise Central Component 5.0
- SAP R/3 Enterprise Central Component 6.0
- SAP ERP 6.0 - Enhancement Packages (1,2,3,4,5,6)
SAP R/3 was arranged into distinct functional modules, covering the typical functions in place in an organization. The most widely used modules were Financial s and Controlling (FICO), Human Resources (HR), Materials Management (MM), Sales & Distribution (SD), and Production Planning (PP).
Each module handled specific business tasks on its own, but was linked to the others where applicable. For instance, an invoice from the billing transaction of Sales & Distribution would pass through to accounting, where it will appear in accounts receivable and cost of goods sold.
SAP typically focused on best practice methodologies for driving its software processes, but more recently expanded into vertical markets. In these situations, SAP produced specialized modules (referred to as IS or Industry Specific) geared toward a particular market segment, such as utilities or retail.
SAP based the architecture of R/3 on a three-tier client/server structure:
- Presentation Layer (GUI)
- Application Layer
- Database Layer
SAP allows the IT supported processing of a multitude of tasks, occurring in a typical company or bank. SAP ERP is differing from R/3 mainly because it is based on SAP NetWeaver: core components can be implemented in ABAP and in Java and new functional areas are mostly no longer created as part of the previous ERP system, with closely interconnected constituents, but as self-contained components or even systems.
Application Server 
An application server is a collection of executables that collectively interpret the ABAP/4 (Advanced Business Application Programming / 4th Generation) programs and manage the input and output for them. When an application server is started, these executables all start at the same time. When an application server is stopped, they all shut down together. The number of processes that start up when you bring up the application server is defined in a single configuration file called the application server profile. Each application server has a profile that specifies its characteristics when it starts up and while it is running. For example, an application server profile specifies:
- Number of processes and their types
- Amount of memory each process may use
- Length of time a user is inactive before being automatically logged off.
The Application layer consists of one or more application servers and a message server. Each application server contains a set of services used to run the R/3 system. Not practical, only one application server is needed to run an R/3 system. But in practice, the services are distributed across more than one application server. This means that not all application servers will provide the full range of services. The message server is responsible for communication between the application servers. It passes requests from one application server to another within the system. It also contains information about application server groups and the current load balancing within them. It uses this information to choose an appropriate server when a user logs onto the system.
The application server exists to interpret ABAP/4 programs, and they only run there. If an ABAP/4 program requests information from the database, the application server will send the request to the database server.
Server-to-server communications can be encrypted with the SAP cryptographic library. With the recent acquisition of relevant parts of SECUDE, SAP can now provide cryptography libraries with SAP R/3 for Secure Network Communications and Secure Socket.
See also 
- Esteves, J., and Pastor, J., Enterprise Resource Planning Systems Research: An Annotated Bibliography, Communications of AIS, 7(8) pp. 2-54.
- "Difference bet. ECC 6.0 & SAP R/3 4.7". Itknowledgeexchange.techtarget.com. 2012-06-01. Retrieved 2012-09-12.
- SAP Cryptographic Library (SAPCRYPTOLIB
- SAP to Acquire Software Security Products and Assets from SECUDE