In this article I will tackle about what characteristics does an analyst examine when evaluating a DFD quality. In our previous assignments we are assigned to make a Data Flow Diagram. But before going to the point I will discuss first what a DFD or Data Flow Diagram is and what are its qualities, the steps in creating a Data Flow Diagram and the symbols of a data flow diagram.
What is a Data Flow Diagram?
A DFD or a Data Flow Diagram is a graphical representation that portrays information flow and shows the transforms that are applied as data move form input to input. In other words Data Flow Diagram is a geographical tool that shows, process, flows, stores and external entities in a system. Data Flow Diagram shows the transformation of data into a system. The basic form of Data Flow Diagram is also known as a data flow graph or a bubble chart. The data flow diagram may be used to represent a system or software at any level of abstraction. In fact, DFDs may be partitioned into levels that represent increasing information flow and functional detailed. Therefore, the DFD provides a mechanism for functional modeling as well as information flow modeling. In process flow diagrams, process symbol has got the following entities, process number which tells the number of process, and locality where activity is happening and also the process name. According to some information Data flow diagram process symbol rules symbolize the transformation data. There must be a data flowing into/out of the process. Data Flow Diagram is categorized as either logical or physical. A logical DFD focuses on the business and how the business operates. It describes the business events that take place and the data required and produced by each event. On the other hand, a physical DFD show how the system will be implemented as we mentioned before. Ideally, systems are developed by analyzing the current system and when we add the new features to the new system the DFD will be used is the logical type but finally the best methods to implement the new system should be developed using the physical Data Flow Diagram.
Symbols of a Data Flow Diagram
There are only four symbols used to write the Data Flow Diagram as, this are the symbols:
Process - Rectangular Box
Processes are drawn as rectangular boxes; processes are transformations, changing incoming data flows into outgoing data flows. Rectangular boxes has a descriptive name occupying the middle of the box and also it has a top stripe that contains the identification number in the left and the location or the role carrying out the work on the right, this is optional and used only in the current physical DFD.
Arrow Headed Lines – Data Flow
Double headed arrows can be used (to show two-way flows) on all but bottom level diagrams. Furthermore, in common with most of the other symbols used, a data flow at a particular level of a diagram may be decomposed to multiple data flows at lower levels.
External Entity – Bubble (circle or round corner square)
An external entity is a source or destination of a data flow which is outside the area of study. Only those entities which originate or receive data are represented on a business process diagram. The symbol used is an oval containing a meaningful and unique identifier.
Data Store – Narrow opened rectangle
A data store is a holding place for information within the system: It is represented by an open ended narrow rectangle. Data stores may be long-term files such as sales ledgers, or may be short-term accumulations: for example batches of documents that are waiting to be processed. Each data store should be given a reference followed by an arbitrary number.
According to some information these are some of the elements of a Data Flow Diagram.
Resource Flow
A resource flow shows the flow of any physical material from its source to its destination. For this reason they are sometimes referred to as physical flows. The physical material in question should be given a meaningful name. Resource flows are usually restricted to early, high-level diagrams and are used when a description of the physical flow of materials is considered to be important to help the analysis.
Data Stores
In some of the information, the store should be given a reference letter, followed by an arbitrary number. These reference letters are allocated as ‘D’ that indicates a permanent computer file, ‘M’ that indicates a manual file and ‘T’ that indicates a transient store, one that is deleted after processing. Most important thing is that in order to avoid complex flow, the same data store may be drawn several times on diagram. Multiple instances of the same data store are indicated by a double vertical bar on their left hand edge.
Processes
When naming processes we should avoid glossing over them, without really understating their role. Indications that this has been done are the use of vague terms in the descriptive title area - like 'process' or 'update'. The most important thing to remember is that the description must be meaningful to whoever will be using the diagram.
External Entities
It is normal for all the information represented within a system to have been obtained from, and/or to be passed onto, an external source or recipient. These external entities may be duplicated on a diagram, to avoid crossing data flow lines. Where they are duplicated a stripe is drawn across the left hand corner, like this. The addition of a lowercase letter to each entity on the diagram is a good way to uniquely identify them.
Characteristics of an Analyst in Examining a DFD Quality
This time I will tackle about what are the characteristics an analyst should developed or should have in examining a DFD quality. After defining what a DFD is, what the steps in making a DFD are or how to create, what are the symbols of a DFD and what are its qualities, I came up with an answer that an analyst should have an interest of what he/she is doing because no one can successfully make a data flow diagram if he/she does not have an interest because we can make the diagram if we will have an interest in making it, another characteristic is an analyst should be observant. Being a good observant is one of the best characteristic an analyst should have in making DFD because when we observe well the flow of the system of the company we can make the proper and the appropriate DFD for it, by observing we can surely tell whether this man is in this kind of work or what are the different roles of the people in the company or in the system. Another important thing is an analyst should make sure that the DFD is understandable to the people, because it is very important that a DFD should be clear to the people around the system in order for them to know the process and the flow of their system well and also they must be able to understand the actual movement of the system and how the model describes it. An analyst is requires also to accept proposals or corrections in order to know the ideas of the people that are being surrounded in the system. Another important thing is an analyst should generate the maximum solution of the problem, he/she must be able to explain the logic solutions, and also an analyst should always evaluate the data flow diagram for accuracy or perfection and the most important thing an analyst should develop is he/she must willing to communicate to the people writing or orally, he/she must get along with them and he/she must be a good listener in order to feel the reaction of the people. And according to my article or according to my previous assignments, an analyst is not expected to be good in the aspects of programming, the most important thing is he/she must have a general knowledge in the concepts and terms and the essentials of the system. And most importantly an analyst should be business minded.
Conclusion
To sum it all up or to generalize what are the characteristics of an analyst in examining a Data Flow Diagram quality. He/she must have a good background of what are the systems that existed and he should also be able to identify what are those processes that a system must have with regarding to the goals of the organization. And he must have enough background on what is their business processes. Good communication skills as well as good critical thinking. And also an analyst must gather important information in order to have sufficient information in making a DFD. And lastly, being able to adapt to change, as we all know we are in the fast changing world or era. Well, that’s it. These are the characteristics that a good system analyst must have in order to evaluate the Data Flow Diagram quality.
