Difference between transaction mapping and transform mapping in dfd
Answers
Explanation:
Each action path flows into a single transform, display messages and status. The design steps for transaction mapping are similar and in some cases identical to steps for transform mapping . A major difference lies in the mapping of DFD to software structure.
Answer:
Transform Flow
Information enters at a point, transformed, and exit at another point
Path: incoming flow, central transform, outgoing flow
Transaction Flow
Single data item, transaction, triggers one of many paths
Path: incoming flow, transaction centre, action path
Explanation:
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.
An Example
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.
Transaction Mapping
In many software applications, a single data item triggers one or a number of information flows that effect a function implied by the triggering data item. The data item, called a transaction, and its corresponding flow characteristics. In this section we consider design steps used to treat transaction flow.
An Example
Transaction mapping will be illustrated by considering the user interaction subsystem of the SafeHome software.
As shown in the figure, user commands flow into the system and results in additional information flow along one of three action paths. A single data item, command type, causes the data flow to fan outward from a hub. Therefore, the overall data flow characteristic is transaction oriented.
It should be noted that information flow along two of the three action paths accommodate additional incoming flow (e.g., system parameters and data are input on the "configure" action path). Each action path flows into a single transform, display messages and status.
