QUIZ DFD
DATA FLOW DIAGRAM
Data flow diagram (DFD) is a picture of the movement of data between external entities and the processes and data stores within a system
Data flow diagram describe system distribution into smaller module,easy to understand the system for less computer knowledge user
Context Diagram
A data flow diagram (DFD) of the scope of an organizational system that shows the system boundaries, external entities that interact with the system and the major information flows between the entities and the system
• consist of one process and describe scope from a system
• highest level from DFD that describe entire input to system and outpur from system
• system is limitted by boundary (described by broken offs line)
• there may not be any storage
several things that must be consider in drawing Context Diagram;
• System Terminology:
• system limit is limits between “importance sistem area”.
• system environment are everything that connected or give influence for system.
• interfaces is flow that connect a system with system environtment.
• use one process simbol, Note:
• information processing activity (system limit).information activity are take data from file, data transformation, or do filing data, for example prepares document, put in document, investigate, clasify, regulate, sort, count, abstracting data, and do filing data (both for doing manual to otomatic.
• name/explanation at process simbol as according to system function,
• between entitas external entity/minator direct communication is not permitted
• if found termintor that has many inputs and product, permitted to described more than one so that prevent depiction too complex, with give asterisk sign () or cross line ().
• if minator represent individual (staff) best represented by character that staff self.
• data flow as input or outpu process have different eksplanation
Level-O Diagram
A data flow diagram (DFD) that represents a system’s major processes, data flows and data stores at a high level of detail
• describe process of dfd
• give opinion according to comprehensive hit system that handled, show function or principal process, data current and eskternal entity
• in level this maked data existence storage
• for process is not detailed again in level furthermore so added simbol ‘*’ or ‘p’ by the end of process number
• balance input and output (balancing) between diagram 0 with context diagram must be taked care
•
Detail Diagram :
• be diagram that elaborate what process is there in diagram zero or level at on it
• numberization level in dfd:
Level Name Diagram Name Proses Number
0 Context
1 Diagram 0 1.0, 2.0, 3.0, …
2 Diagram 1.0 1.1, 1.2, 1.3, …
3 Diagram 1.1 1.1.1, 1.1.2, …
• in one level best not found more than 7 process and maximal 9, So there are more dekomposition
• Every process on DFD must have spesification process
• in top level method that used to describe process can by using descriptive sentence
• in level detailer that is in process most under (functional primitive) need spesification structureder
• process spesification will be guide for programmer to make program (coding)
• method that used in process spesification: process explanation in the form of story, decision table, decision tree
Eksternal Entity
• something that beyond system, but it gives data into system or give data from system
• symbolized with notation box
• external entity doesn’t belong part from system
• Nomenclature:
o terminal name shaped noun
o terminal may not has name same except the object really same
Rule: Eksternal Entity
External people, systems and data stores
Reside outside the system, but interact with system
Either a) receive info from system, b) trigger system into motion, or c) provide new information to system
e.g. Customers, managers
Not clerks or other staff who simply move data
Must be connected to a process by a data flow
DATA FLOW
• become place for currences information
• described with straight line that connect component from system
• data current is showed with arrow direction and line is given name on data current that flow
• data current flows between process, data storage and show data current from data shaped input to system
data current example as input to system shaped like;
a. form atatu document that used at company
b. Handout printed that produced by system
c. input to computer
d. pronunciation communication
e. data transmission from a computer to computer other
DATA FLOW (2)
• naming guide:
o data current name that consist of several word currents relateds with line continues
o there may not be any data current the name same and name gift must reflect its contents
o data current that consist of several elements can be declared with element group
o void using word ‘data’ and ‘information’ to give name in data current
o data current name must written complete
DATA FLOW (3)
• Other Rules:
o data current name that come into a process may not equal to secretory data current name from process
o data flow that step into or out from data storage unnecessary given name if:
Data flow is simple and easy to understand
Data Flow describe all data item
there may not be any data current from terminal to data storage or on the contrary because terminal not part from system, terminal connection with data storage must pass process Rule: ARUS DATA
Data in motion, moving from one place to another in the system
From external entity (source) to system
From system to external entity (sink)
From internal symbol to internal symbol, but always either start or end at a process
PROCESS
• process is what done by system
• process can cultivate data or data current enters to be data current out
• process functioneds transformate one or several input datas become one or several product datas as according to desirable spesification
• every process has one or several inputs with produce one or several products
• Process vary called bubble
PROCESS (2)
• Naming Rules for process:
o process name consists of verb and noun that reflect process function
o don’t use process word as part from name a bubble
o there may not be any several process that has names same
o process must be given number. sequence number may be follow current or sequence process, but such sequence meaningless number absolutely is sequence process chronologically
DATA STORAGE
• data storage is existing data repository in system that can be in the form of as follows this.
• file or database at system computer.
• archives or note manual.
• data place box at somebody table.
• reference table manual.
• agenda or book.
o symbolized with a pair parallel line or two lines with one sides opened
o on the picture D1 is symbol storage media as does book or archives, while students stored data name.
• process can take or give data to database
• Naming rule:
o name must reflect data storage
o when does the name more than one word so be must be given sign continue
Rule: Data Store
Internal to the system
Data at rest
Include in system if the system processes transform the data
Store, Add, Delete, Update
Every data store on DFD should correspond to an entity on an ERD
Data stores can come in many forms:
Hanging file folders
Computer-based files
Notebooks
Must have at least one incoming and one outgoing data flow
SIMBOL DFD
Data Dictionary
• functioned to help system executant to interpret application in detail and organize all data element that used system according to exactly so that user and has base explanation same about input, product, storage and process
• in analysis stage, data dictionary is used as a means of communication between system analyst with user
• in system planning stage, data dictionary is used to design input, report and database
• Data current in DFD was global, detail explanation visible in data dictionary
KAMUS DATA (2)
• data dictionary contains the followings:
o data current name: must be registerred so that reader that need furthermore explanation about a data current can look for easily
o alias: alias or other name from data can be written if (there are) any
o data form: used to group data dictionary into its use when system planning
o data current: show from which data flows and where does data aim
o explanation: give explanation about meaning from data current
BALANCING DFD
• current data that come into and out from one process must equal to current data that comes into and out from process details in level/stage at under it
• data flow name that come into and out from one process must equal to data flow name that enters to and out from process details
• total and name entity outside from a process must equal to total and name entity outside from process details
• matters that must be considering in dfd that has more than one level:
o must found balance input and output between one level and level next
o balance between level 0 and level 1 seen in input/output from data current to or from terminal in level 0, while balance between level 1 and level 2 seen in input/output from data current to/from process concerned
o current data name, data storage and terminal in every level must same if the object same
Prohibition in DFD
• data flow may not from outside entity direct aim to another outside entity without pass a process
• data flow may not from data savings direct aim to outside entity without pass a process
• data flow may not from data savings direct aim to another data savings without pass a process
• data flow from one process direct aims to another process without pass a data savings may avoided
