Various analysis and design methods developed over time to support the analysis of the events and processes of real-time systems.

Analysis and design grew out of advances in computer programming in the early 1970s, when programmers began incorporating control structures into their work. This method, which became known as structured programming, made programs easier to write, test, and maintain. In the mid-1970s, structured programming spawned structured design. Structured design is a technique for factoring computer programs into independent modules. It suggests that you design modules to serve one and only one function, resulting in a top-down hierarchy of modules.

The structured analysis technique is simple in concept: the analyst defines what the system should do before deciding how it should do it. The new systems specification evolves from a series of data flow diagrams. These diagrams show the flow and storage of as well as the processes that respond to and change data.

Structured analysis is a process-oriented approach. That is, the analyst is most concerned with the kinds of processing, or functions, that the system needs to do.

Over time, data flow diagrams were supplemented by data models to fully describe systems. Whereas data flow diagrams focus on processing, data models, also known as entity relation diagrams, enable analysts to understand the data of a system independently of its use.

In real-time systems, analysis of the data is less important than analysis of the events that cause transitions in the system, and processes to be performed. Stephen Mellor and P. Ward’s work in the mid-1980s advanced the state of analysis and design of real-time systems using data flow diagrams and state diagrams. (Mellor’s object-oriented approaches, developed in the 1990s with Sally Shlaer, are also supported by System Architect (see Object- and Component-based design with Shlaer/Mellor)).

System Architect supports the Structured Analysis and Design techniques and supporting diagrams listed below: