Data flow diagram

Data flow drawData Flow DiagramDFD is a organization modeling tool, the most habitual and important representations in selective in airation flow modeling. DFD allows us to picture a system as a network of functional processes, connected to whiz another(prenominal) by pipelines and holding tanks of info. It is a structured, diagrammatic technique representing external entities, logical storage, in put to workation sinks and data flows in the system. You jakes withal call DFD as spew out chart, bubble diagram, process model, and work flow diagram.Data Flow Diagram TypesPhysical Data Flow Diagram Physical data flow diagrams ar implementation-dependent and arrangement the actual devices, break downment, people, etc., involved in the current system.Logical or Conceptual Data Flow Diagram Logical data flow diagram represents business functions or processes. It describes the system independently of how it is actually implemented, and focuses rather on how an activity is accompli shed.The comp binglents of the data flow diagram (DFD)Processes The basic processing items of a data flow diagram. They be employ to transform incoming data flows into outgoing data flows. Processes that argon not further decomposed convey to be described by means of a textual specification. This text defines how the input data of the process atomic number 18 transformed into output data.Terminators Data producers (data sources) or data consumers (data sinks) outside of the systemData flows Logical channels (pipelines) in which data are transported they are represented by arrows connecting the processesData introduce Storage space from which data can be read with a time delay after writing them without processing component.Data flow diagrams are useful ifyou have lots of calculations to channelise outYou are familiar with data flow techniques in a method you have used repeatedly before.The approach to data flow diagramming should be as followscreate a data flow diagram for apiece of the chew over outputs of the systemwork back from the outputs to the inputs to construct the diagram attach new tendencys where necessary to the endeavor model as you discover the need for them in the data flow modelingadd new operations and attributes to the object model as you discover the need for them in the data flow modelling Data Flow DescriptionThe data flow symbol is a line with an arrow showing the direction of flow. It should be named using words that are understood within the department or organization describing the data. The data that leaves one process is exactly that which arrives at the next process. An arrow usually at the end of the flow line indicates direction of flow. External Entity DefinitionThe external entity is a source or recipient of data that is outside the boundary of investigation. The fundamental purpose of this symbol is to indicate that whatever happens at the end of the data flow,Entity birth DiagramA logical data model is document ed as an entity relationship model supported by the data items for each entity (conventionally in the form of a Third Normal Form relation).Though the relationship among data gillyflower is not emphasized in data flow diagram, it is well reflected in ERD. ERD is one of the most useful model forming tools to organize this discussion. ERD is network model that describes stored data of a system at a high level of abstraction. For system analyst, ERD has a major benefit it highlights the relationship between data stores on DFD which would otherwise only be seen in the specification process.The main components of an ERD includeEntity- a subject, a duty, or an event that has a significant meaning to the future systemAttribute the characteristics of the entity displayed by fields or columns of a table.Relationship- There is 3 major cases of relationship used in ERDsOne one relationshipOne many relationshipMany many relationshipEntity- is any type of object that we wish to store data a bout. Which entity types you decide to include on your diagram depends on your application. In an accounting application for a business you would store data about customers, suppliers, products, invoices and payments and if the business manufactured the products, you would need to store data about materials and production steps. Each of these would be classified as an entity type because you would want to store data about each one. In an entity-relationship diagram an entity type is shown as a box. There may be many entity types in an entity-relationship diagram. The name of an entity type is singular since it represents a type.Attributes-The data that we want to keep about each entity within an entity type is contained in attributes. An attribute is some quality about the entities that we are interested in and want to hold on the database. In fact we store the value of the attributes on the database. Each entity within the entity type allow for have the same set of attributes, but in general different attribute values. For example the value of the attribute ADDRESS for a customer J. Smith in a CUSTOMER entity type energy be 10 Downing St., London whereas the value of the attribute address for another customer J. Major might be 22 Railway Cuttings, Cheam.Cardinality and OptionalityThe maximum degree is called cardinality and the minimum degree is called Optionality. In another context the terms degree and cardinality have different meanings. In Date 4th ed. p240 degree is the term used to denote the number of attributes in a relation while cardinality is the number of tipples in a relation. Here, we are not talking about relations (database tables) but relationship types, the associations between database tables and the real world entity types they model.Entity DescriptionsCustomerInfoThis entity is to store the personal Name, Address etc in to check in the Hostel. wrinkleThis entity is to store the detail of stock items in order to check new item.Check InTh is entity is to store the Customer cultivation that was get to the Room.BookingThis entity is to store the Room that have been booking according to customers order.RoomThis entity is to store the Room information of the Hostel status.Sale ServiceThis entity is to store the sale record of each customer and the item.Entity Life HistoryThe ELH technique is based on concepts developed by Michael capital of Mississippi for structured program design. The essential idea is that all data processing can be described in terms of sequence (order), selection (choice) and iteration (repetition) of processing components, which are derived from the data structures. In an ELH these ideas are used by analogy to model sequences, selections and iterations of events guessing an entity.In between the birth and death events there may be a number of life events. Jackson rules are observed in that the diagram shows that it is possible for there to be no changes between creation and end of life for a par ticular instance, as an iteration may occur zero, one or many times.Parallel lives are used when there are two (or more) independent sets of events that can affect an entity. As events from the two sets are not dependent on each other, but only on events from their own set, they cannot be ordered together in a predictable way.Quits and resumes are a means of jumping from one part of the diagram to another in order to cope with exceptional or unusual events. If used indiscriminately they can undermine the apparent structure of the diagram and make it more difficult to understand. Analysts should therefore use a quit and resume only when they are sure that there is no sensible way in which they can use normal Jackson structures to show what they want. NormalisationAny collection of attributes can be said to be either unnormalised or in a particular normal form depending on its compliance with the rules given below. Many normal forms have been defined. Codd originally defined firstbo rn, second and third normal forms. There are some cases, particularly where keys are complex and contain many attributes, where further normalization may be required. For such cases, Boyce- Codd normal form, fourth normal form and fifth normal form also exist. In this book, normalization will only be covered up to the third normal form, since this is sufficient for most practical purposes. For further information about the other normal forms the reader is referred to Data (2000).Report for National Hostelling AssociationThere are a lot of advantages when compared to the manual system and computing machine based system. Although our system is still window based.We will be able to room service, Ecommerce application in the future. We have made the information giving in our system easily understandable for new uses of the system.The display area of the store is not very large. It will only display a small instalment of the Room Other Sale Item that the Check in the Hostel room. My s ystem will allow customers to choice rooms . This will allow customers to beg room and service that are not on display. The customer can search the room by keyword or by category such as room,Booking No, CheckIn/Out etc or by charges. The charges will take the discount value for each invoice ie, the For manager, he will help with this activities during busy periods and will be responsible for the general management duties such as accounting, correspondence, staffing etc. The manager will also Booking and necessary from a number of customers and he will also decide which of the services will be discount prices to the customer. In order to do this, he will need the information from the system. The system also produce the monthly report in order to estimate the rooms status and the customer like and dislike of the services ie the customer effort according to the season.These above information are explained about the functions of the National Hostelling Association.To have a successfu l system design for the National Hostelling Association, I have to study the manual system first. Then I draw the context diagram. The context diagram shows the entire system as a single process contact by the external entities. The National Hostelling Association, Context diagram represents data input and output flows. This make to concentrate or focus on the boundary to be investigated. This can give great help in discussing with the user on the scope of the system.Aims and objectives are given to the system so the system user cannot depart from the system needs. As the context diagram is drawn, the level 1 DFD are also easily drawn to make the system easy to look and to be understandable. This can enhance the clarity of the system to the user.Then I create a data model to support the system information. It points the ways how the data items are grouped together into entities and identifies the relationships between the entities. To get the attributes for the entities, I studied the manual records and the receipts of the National Hostelling Association. Additional characteristics such as the optionality and degrees of relationship are inevitable to identify for the entities.Then I studied how the entities change with time.ELH is described to know the creation of an entity occurrences, record the sequence of changes in the system during its life time and how it ends in the system.Then I do the normalization which provides the sound foundation for physical design which can be implemented as the database design. For database design, all entities are include in the data dictionary which is the sources of information of the system.Then, I create the prototype by using Visual Studio 2005. It includes searching for an item of National Hostelling Association. I also take the screenshots of the prototype and identify where the system needs the validation rule.All the tasks shown above demonstrate an understanding of the modeling and installation of the data compul sive system. They demonstrate the analysis and design of a system including the prototype use interface, training plans for the users.Preparation for the installation of the systemIn order to install the system, we first need to install the hardware first. Then we need to do the data entry for the items. We also need to install the software required to run the system.The requirements are as followsHardware RequirementsPentium IV or aboveProcessors is C.P.U. 1.8 GHz or above.Memory (RAM) is 512MB or above.Hard Disk space is 1GB for my system and 10 GB for Operation System.Software RequirementsWindow XPVisual Studio 2005Microsoft Office Word 2003 for reading Manual Guide