Context Diargam and DFD Scenario

هذا المثال ليس مقررا لطلبة كليات التجارة ولكنه يصف بشكل عام سيناريو اعداد Context Diagram وكذلك اعداد Data Flow Diagram DFD بمستويات Level 0 و Level 1
Scenario: KnowledgeExchange.com
KnowledgeExchange.com is a new Internet-based enterprise specializing in offering distance learning and e-learning for corporations. The company used to conduct training seminars in major U.S cities under the name of Troy Seminars before the advent of e-business. At the turn of new millennium, it embarked on a transformation to an e-business enterprise and changed to the above name. The name change also indicates an expansion of its strategy. Although on-site seminars remain to be its core business at least for now, it moves rapidly to establish new market in distance learning and even one-of-a-kind custom training. Ultimately, the company envisions itself to become a leader in the business of knowledge products exchange facilitating the transactions amongst all kinds of knowledge producers and buyers. The first step of this e-business strategy is to bring the tradition business, on-site seminars, on to the Internet. The core business processes are described below.
For each seminar, the logistic department must make arrangement for the meeting facilities, the training consultant�s travel, and the shipment of any seminar materials. For each scheduled seminar, the bookings department notifies the logistics coordinator of the type of seminar, the date and city location, and the name of consultant who will conduct the training. To arrange for meeting facilities, the logistics coordinator gathers information on possible meeting sites in the scheduled city. The meeting site location is made based on date availability, cost, type of meeting space available, and convenience of the location. Once the site decision is made, the coordinator speaks with the sales manager of the meeting facilities to reserve the meeting room(s), plan the seating arrangement(s), and reserve any necessary audio-visual equipment. The coordinator estimates the number and size of meeting rooms, the type of seating arrangements, and the audio-visual equipment needed for each seminar from the information kept in a logistics database on each type of seminar offered and the number of anticipated registrants for a particular booking. After negotiations are conducted by the logistics coordinator and the sales manager of the meeting facility, the sales manager creates a contract agreement specifying the negotiated arrangements and sends two copies of it to the logistics coordinator. The coordinator reviews the agreement and approves it if no changes are needed. One copy of the agreement is filed and the other copy is sent back to sales manager. If changed are needed, the agreement copies are changed and return to the sales manager for approval. This approval process continues until both parties have approved the agreement. The coordinator must also contact the training consultant to make travel arrangements. First, the coordinator reviews the consultant�s travel information in the logistic database and researches flight schedules. Then the consultant is contacted to discuss possible travel arrangements; subsequently, the coordinator books a flight for the consultant with a travel agency. Once the consultant�s travel arrangements have been completed, a written confirmation and itinerary are sent to the consultant. Two weeks before the date of seminar, the coordinator determines what, if any, seminar materials (e.g., transparencies, training guides, pamphlets, etc.) need to be sent to the meeting facility. Each type of seminar has a specific set of materials assigned to it. For some materials, the coordinator must know how many participants have registered for the seminar in order to determined how many to send. A request for material is sent to the material-handling department where the materials are gathered, boxed, and sent to the meeting address list on the request. Once the requested materials have been shipped, a notification is sent to the logistics coordinator.
Steps:
Draw the context diagram
The external entities of this system are Participant, Sales_Manager_of_Seminar_Site, Consultant, Travel_Agency, and Meeting_Facility. These external entities send inputs to and/or receive outputs from the system as follows:

• The system gets order for a specific seminar from Participant and sends Accepted/Rejected notification to it.
  
• The system collects site information from Sales_Manager_of_Seminar_Site and sends information on facilities needed to the selected Sales_Manager_of_Seminar_Site that sends contract agreement back to the system.
  
• The system sends a traveling proposal to Consultant who confirms the proposal. Once the system gets a confirmation on the traveling proposal from Travel_Agency, it sends an arrangement confirmation to the consultant.
  
• The system sends information on a consultant and flight desired to Travel_Agency. Once the Travel_Agency books a flight for consultant, it sends a confirmation to the system.
  
• The system sends a material request with seminar materials to Meeting_Facility.
  

The complete context diagram is shown in Figure 3.1.

Figure 3.1: The Context Diagram for KnowledgeExchange.com.
Develop the detailed DFD model


In Figure 3.1, we established in context in which the system is supposed to operate in terms of external sources and destinations of data flows. Now, we begin on the process itself. First, we recognize four basic processes: process 1 Process_Order, process 2 Arrange_for_Meeting_Facility, process 3 Arrange_for Training_Consultant�s_Travel, and process 4 Arrange_Seminar_Materials. The process 2 and 4 can be decomposed further. The descriptions of processes are as follows:

• The process 1 Process_Order gets order information from Participant entity, retrieves a seminar for the order from a data store �Seminar,� and makes a decision on the order. The result from the decision is sent to the Participant and to update the data store seminar to reflect a number of registrants. The number of registrants is used in the process 4 Arrange_Seminar_Materials.
  
• The process 2 Arrange_for_Meeting_Facility decides the seminar site based on site information from the entity �Sales_Manager_of_Seminar_Site� and information from data store �Seminar� on type of seminar, date, and city location. Once the site is decided, this process updates site information in data store �Seminar.� The process estimates meeting facilities using information (1) from data store �Seminar� on type of seminar, date, site, and size; and (2) from data store �Logistics_Database� on facilities needed for each type of seminar. The list of facilities needed is sent to the entity �Sales_Manager_of_Seminar_Site.� The contract based on this list is sent back to the system. The system then stores that contract in the data store �Contract.� According to this analysis, we decompose the process 2 into three processes: process 2.1 Decide_Seminar_Site, process 2.2 Estimate_Meeting_Facilities, and process 2.3 Create_Contract. The DFD for this process in shown in Figure 3.3.
  
• The process 3 Arrange_for Training_Consultant�s_Travel generates a traveling proposal for a consultant using consultant name from data store �Seminar�, consultant travel information from data store �Logistics_Database,� and flight schedule information from data store �Flight_Schedule.� This process also stores consultant travel arrangement in data store �Consultant_Travel.� The data flows to/from external entities �Consultant� and �Travel_Agency� are as described in the step �draw the context diagram�.
  
• The process 4 Arrange_Seminar_Materials uses information from data store �Seminar� on type and number of registrants to determine a material request according to information in data store �Material�-that specifies a set of material for each type of seminar. The request is sent to data store �Material_Request.� This process also arranges shipping by getting request information from data store �Material Request,� produces the request sent with seminar materials to Meeting_Facility, and updates the status of the request. According to this analysis, we decompose the process 4 into two processes: 4.1 Determine_Material_Request and process 4.2 Arrange_Shipping. The DFD for this process is shown in Figure 3.4.
  

Figure 3.2: The level 0 DFD for KnowledgeExchange.com.

Figure 3.3: The level 1 DFD for process 2 Arrange_for_Meeting_Facilities.

Figure 3.4: The level 1 DFD for process 4 Arrange_Seminar_Materials