Latest recent. Software Engineering-Transform Mapping. Transform mapping is a set of design steps that allows a DFD with transform flow characteristics to be mapped into a specific architectural style. In this section transform mapping is described by applying design steps to an example system—a portion of the SafeHome security software. The SafeHome security system is representative of many computer-based products and systems in use today.
The product monitors the real world and reacts to changes that it encounters. It also interacts with a user through a series of typed inputs and alphanumeric displays. The level 0 data flow diagram for SafeHome, is shown in figure. During requirements analysis, more detailed flow models would be created for SafeHome.
In addition, control and process specifications, a data dictionary, and various behavioral models would also be created. The preceding example will be used to illustrate each step in transform mapping. The steps begin with a re-evaluation of work done during requirements analysis and then move to the design of the software architecture.
Step 1. Review the fundamental system model. The fundamental system model encompasses the level 0 DFD and supporting information. In actuality, the design step begins with an evaluation of both the System Specification and the Software Requirements Specification. Both documents describe information flow and structure at the software interface. Figure 1 and 2 depict level 0 and level 1 data flow for the SafeHome software.
Step 2. Review and refine data flow diagrams for the software. Information obtained from analysis models contained in the Software Requirements Specification is refined to produce greater detail. For example, the level 2 DFD for monitor sensors is examined, and a level 3 data flow diagram is derived.
At level 3, each transform in the data flow diagram exhibits relatively high cohesion. That is, the process implied by a transform performs a single, distinct function that can be implemented as a module9 in the SafeHome software. Therefore, the DFD in figure contains sufficient detail for a "first cut" at the design of architecture for the monitor sensors subsystem, and we proceed without further refinement.
Step 3. Determine whether the DFD has transform or transaction flow characteristics. In general, information flow within a system can always be represented as transform. However, when an obvious transaction characteristic is encountered, a different design mapping is recommended. In this step, the designer selects global softwarewide flow characteristics based on the prevailing nature of the DFD.
In addition, local regions of transform or transaction flow are isolated. These subflows can be used to refine program architecture derived from a global characteristic described previously. For now, we focus our attention only on the monitor sensors subsystem data flow depicted in figure. Evaluating the DFD , we see data entering the software along one incoming path and exiting along three outgoing paths. No distinct transaction center is implied although the transform establishes alarm conditions that could be perceived as such.
Therefore, an overall transform characteristic will be assumed for information flow. There are 2 different types of information flow that have different treatments Transform flow - Overall data flows in sequential manner and follows one, or only a few, straight line paths. Transform Flow Incoming Flow: The paths that transform the external data into an internal form Transform Center: The incoming data are passed through a transform center and begin to move along paths that lead it out of the software Outgoing Flow: The paths that move the data out of the software.
Design steps Step 1. Review the fundamental system model. Step 2. Review and refine data flow diagrams for the software. Step 3. Determine whether DFD has transform or transaction flow characteristics. Step 4. Isolate the transform center by specifying incoming and outgoing flow boundaries different designers may select slightly differently transform center can contain more than one bubble.
Step 5. Perform first-level factoring program structure represent a top-down distribution control. Step 7. Refine the first iteration program structure using design heuristics for improved software quality.
Transaction Flow Information flow is often characterized by a single data item, called a transaction that triggers other data flow along one of many paths Action Paths :The transaction is evaluated and based on its value flow along one of many action paths Transaction center :The hub of info flow from which many action paths originate. Open navigation menu. Close suggestions Search Search. User Settings.
Skip carousel. Carousel Previous. Carousel Next. What is Scribd? Explore Ebooks. Bestsellers Editors' Picks All Ebooks. Explore Audiobooks. Bestsellers Editors' Picks All audiobooks. Explore Magazines. Review the fundamental system model. Step 2. Review and refine data flow diagrams for the software. Step 3. Determine whether the DFD has transform or transaction flow characteristics. Step 4. Isolate the transform center by specifying incoming and outgoing flow boundaries.
Step 5.
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