Information Systems Development - Assignment Example

Information Systems Development and Practice 3 (UFIE98-20-3) Question There exist several database models that are used for implementing database systems. Which model the designer will choose to employ is strictly up to the database system to be developed taking in mind the properties and the relations of the entities of the database system. In this case we need to examine the way the data are structured in order to define the database models to adopt. Database systems according to the way they function they are categorized in analytic and operational but here we are concerned with how they model the data in which case they are divided into hierarchical and network databases. Here the Police Identity Parades system has two characteristics; first not everyone is able to view all the data and second and most important is that not ALL the information is locally saved for each agency but rather information is extracted from a central system Criminal Records Database (CCRD). In this case matching which is the subject here is done as such; information is extracted from the central database and some operations are performed locally. This model then requires a client/server database model that will give the users the chance to retrieve data from the central database and perform operations on them (thinkquest.com). This is also an analytic database meaning that it does only retrieve some data and performs queries on them without doing any alterations. Heartline, on the other hand has a paper based subsystem involved in their general system. Here a registration is received and has to go through some human based procedure before reaching the electronic part of the system and the database. In this case we are using an On Line Transaction Processing (OLTP), relational database that performs more operations like adding and modifying data. Question 2 The EDR diagram is depicted in the following: Question 3 According to the previous ERD the following entities have been identified: 1. volunteer 2. suspect 3. parade 4. witness 5. CRB Each of the following with their properties is described here: Volunteer: SSN primary key Name Address Phone Sex Salary Suspect ID primary key Name Address Phone Sex Parade No primary key VolunteersNm foreign key to volunteers SuspectsNm foreign key to suspects Witness SSN primary key ParadeNo foreign key to viewed parade Name Adress Sex CRB ID primary key SuspectSSN foreign key to suspect SSN Name Location Question 4 The data flow diagram for the Heartline agency is as follows: Question 5 1. As soon as a suspect is taken into custody and the parade is formed the volunteers attends the parade to view the "volunteers". 2. Before the parade the volunteers have to be matched to verify if they exist, or vetted by the CRB to make sure to that certain criminals do not get involved with the Police procedures. 3. The parade takes place or about an hour and the witness view the volunteers 4. The suspects are held into custody 5. After the parade the "volunteers" are given a 20 pounds fee. Question 6 The police parade system "volunteers" matching system requires that the 5 people to form the parade are brought in and cross referenced with the CRB to make sure that they are not involved in the police process. After this the parade is made and the suspect is held into custody releasing the other suspects. In the second case where with the Hearthline system, it is so that the person is matched with other people that exist in the database, therefore, there is the need for identical characteristics to be matched. In the first case the suspect is compared to the "volunteers" and then the most appropriate is chosen or better held into custody by the police where is the other case of the Heartline agency the person is matched with other people until a match is made. In case that there is no match available then the customer is given a refund. In the first case there is a one-to-one matching of the suspect with a "volunteer" while in the second case there is a one-to-many matching of the customer with the possible dates. This differs from the police agency system in that there is an alternative case that if the customer is not matched then the next in the list is contacted to match the customer and if the whole procedure fails then the customer is refunded. In the police agency system however, the first "volunteers" to match the characteristics of the suspect the most is held into custody and the rest are released. The system job ends here and there is no further search of the appropriate "volunteer". Question 7 As far as the police agency system is concerned the identification process followed requires that the suspect is cross referenced with the "volunteers" to identify identical characteristics. Here because we have the case of the suspect who is held into custody the characteristics sought need to be exactly the same as the query because a person who just happens to match the description cannot be held into custody, simply because some of the properties he/she hold match those of the suspect. Therefore, there is the need of an exact match. If the suspect is identified then he is held and the case is closed in the case that there are no such the case remains open until the suspect is found or it is decided to close the case. The security here is that there needs to be an EXACT match of the suspect in order to consider putting someone in jail. Question 8 Could not produce the pamphlet because I did not understand the use of it, but is the identification process for the Heartline agency: the data is received and the customer is registered. Once the customer is registered and the matching profile satisfies their needs the customer will be cross referenced with other customers through their interests and other properties in order to find matches. This requires searching the database of customers to come up with identical keywords. The customers with the biggest number of identical characteristics are contacted first and in case that this matching fails then the next customer with the most characteristics matching another is contacted and they are contacted. The system is safe since the data held of the customers are available only to a small number of workers and noone else has access to them Question 9 No pamphlets were designed but it is the case here that the process of the explanations given earlier is justified. In the case of the police parade system the effort is given to make sure that the police agency understands that the system is safe and effective because it only identifies the "volunteer" that completely matches the suspect. This case is very important because it endangers the reputation of the police firstly and second needs to make sure that the police understands the system is secure since is only identifies a perfect match. In the second case that the heartline agency system fails the customer is deleted from the database and the case is closed. The customer is refunded and there is no further process of finding a match. Moreover, the heartline agency system as said earlier does not require getting the exact match from the database. If it is the case that such a match exists then the two customers are contacted and the matching remains open until the customer decides to declare that a match has been found or in the case that no match exists. Security here is guaranteed with no access of the customer data by irrelevant people and the refund that is given in case the customer is not satisfied. References Types of databases, Retrieved August 21, 2006 from The UK Web Design Company Web Sitehttp://www.theukwebdesigncompany.com/articles/types-of-databases.php Databases, Retrieved August 21, 2006 from ThinkQuest.com Web Site http://library.thinkquest.org/C0115420/Cyber-club%20800x600/DatabaseS/Types%20of%20Databases.htm Data Flow Diagrams Retrieved August 21, 2006 from UWE-CEMS Web Site http://www.cems.uwe.ac.uk/tdrewry/dfds.htm#DFD%20Levels Read More