¶ … greatly help out in conveying the message intended a lot easier to the target audience. The visual aspect given by the diagram allows for the audience to relate better to whatever the speaker is trying to say. Not using a diagram of course is still a viable way to present an idea. But this requires more focus in the part of the audience in order for them to fully understand what is being delivered since they need to tap in to their imagination to picture out what is being presented to them. The idea now is choosing the right type of diagram. In this context, it could be said that there are many types of diagram. This paper will focus on one specific type that is primarily used in showing or capturing a dynamic relation within a specific system. This is the use case diagram. It is necessary though to clarify the definition of the use case diagram since it is somewhat similar to other diagrams with the same purpose. To do this, it is necessary to present another type of the diagram, the activity diagram.

The Use Case Diagram

Once again, by definition, a use case diagram is primarily used in trying to capture the idea of a relationship within a system. The flow of the activities then is presented in how two or more parties interact with each other. Requirements must then be gathered not only from within the system but also from outside itself. This is to ensure that all influences to the system are presented for a clear definition of the entire process.

Actors then are given specific roles to represent the different parties that could possibly affect the system being presented. Each actor will then interact through the diagram specifically on how the parties will relate to each other in real life. A good example of this interaction is the simple case of purchasing glasses. The process will first be defined then the flow of the system will then be presented through a use case diagram. In the situation that will be presented below, three actors are necessary, the patient, the doctor, and the optical dispensary.

First, a patient must know if he or she really needs to have prescription glasses. In order to acquire this knowledge a consultation with an optometrist must be set. Take note though that for more serious cases, the patient might need to have a consultation set with an ophthalmologist instead. Ophthalmologists have far more educational background and are licensed medical doctor (American Academy of Ophthalmology, 2011). Either way, both professions should be able to give the right prescription and/or recommendation if the patient needs glasses or a higher level of medical attention.

During the consultation, the medical history of the patient will be reviewed. The reason for this is to trace any possible causes that might have affected the eyesight of the patient. It is recommended in this part that full honesty must exercised by the patient since every bit of information could pave the way for a more accurate diagnosis.

After the diagnosis, a prescription for the glasses will be finally given by the professional. If this is the patient's first time to be diagnosed, the optometrist or the ophthalmologist should be able to recommend an Optical Dispensary where the patient can order the prescription later. In most cases though, the hospital or the clinic of the professional will already be equipped with its very own Optical Dispensary. If this is the case, the patient will have lesser problem of trying to acquire the new set of glasses.

Once the prescription is acquired by the patient, he or she can now visit the recommended Optical Dispensary. This time, he or she will be given the chance to select the frame for the glasses that were prescribed in the previous set of steps. An optician, who is trained to fit frames, installs the prescribed lenses or set any other devices that the previous professional prescribed, will help out in the selection of the frame. It must be noted though that even though an optician is trained to handle eye care devices, he or she is never allowed to change the diagnosis and thus replace the prescribed lenses for the patient (American Academy of Ophthalmology, 2011).

The desired frame is then selected and it is time to try and fit the frame according to the size best suited for the patient. This is the extent of freedom a patient can have in terms of choosing at will how the glasses will look like. The frames can be changed at will during this step, but the prescribed...

The patient can then place the order for the glasses to be made. Each patient must then wait after this step. Depending on the frame, or the even the frames themselves, making the glasses make take a few hours or up to a week. The diagram below shows the flow of the step-by-step process of this part of buying prescription glasses.
When the schedule for the release of the glasses comes it is time for the patient to return to the Optical Dispensary to try out and see if the glasses fit to what was ordered. It must be noted that the word "fitting" here denotes two meanings. First, fitting refers to the comfort and the size of the frame itself and its effects to the user. Second, fitting also means ensuring that the lenses that were attached to the frame are correct basing on the prescription given by the optometrist or an ophthalmologist during the first step.

If the glasses fit the two categories stated in the previous paragraph, then it is time to pay for the glasses. Depending on the Optical Dispensary's payment procedures, payment here could either be just paying the remaining balance of the fee.

On the other hand, if the glasses that were delivered do not fit any of the two categories mentioned above then payment must not be done just yet. It is necessary in this part to re-order the glasses to ensure that the patient will receive the right specifications. Afterwards, patience is needed once more since the glasses will be remade and the same waiting time might apply as the previous steps.

With this situation, the use case diagram will then look like the figure below.

Figure 1: Use Case Diagram for buying Glasses

It must be noted that this presented through perspective of a patient. A different use case diagram will be created if the perspective is changed to that of the doctor or the optical dispensary.

Activity Diagram

To keep it relatively short, an activity diagram focuses on presenting a specific set of steps within the system. A series of activity diagram then must be created in order to represent the whole system itself.

In creating a diagram, the perspective being used is presented as the start of the diagram, the end of the specific set of steps is then presented as the end of the diagram. Other parties involved will be presented as part of the process that the actor will need to go through.

If the same scenario used earlier is applied, three activity diagrams can be created. These diagrams can be presented as the ones below. Here, the patient is the start of the diagrams and each end can be technically the start of the succeeding diagrams. The doctor and the optical dispensary are presented as parts of the process that the patient needs to follow.

Figure 2: Activity Diagram (Consultation)

Figure 3: Activity Diagram (Ordering)

Figure 4: Activity Diagram (Fitting and Payment)

The difference between the two types of diagram then is clearly seen with these representations. It must be noted though that both can be utilized to complement each other and amplify their effects.

In a sense, upon the delivery of the presentation, activity diagrams can be presented to represent a specific number of steps. This is to ensure that the audience will be able to follow each specific instruction or date more accurately. The series of activity diagrams will then allow the audience to have a starting point after each section making it easier for them to back track or retrace their steps if so ever they somehow encounter a problem throughout the course of the process.

On the other hand, a use case diagram can be utilized as a summary of the entire process. The intended audience should have undergone the process of all the activity diagrams by the time the use case diagram is presented to them. This will allow them to view the entire process as a whole and since they know each part, they will then be able to relate better and picture out themselves in the specific situation.

It is clear then that the use of diagrams have their purpose. Utilizing them properly is a bit trickier but they will definitely help out to make the message being presented easier to digest.

Reference:

American Academy of Ophthalmology. (2011). American Association for Pediatric Ophthalmology and Strabismus. Retrieved January 12, 2015, from American…