Data flow diagrams (DFDs) are a graphical tool used in systems analysis to represent the flow of data through a system. A DFD shows the components of a system, external entities that interact with it, and the flows of data between them. There are different types of DFDs created at increasing levels of detail, including context diagrams, level-0 diagrams, and lower level diagrams. DFDs focus on logical data flows and are useful for communicating with stakeholders and analyzing existing and proposed systems.
Refer to the following figure which contains drafts of a context and l.docxlmarie40
Refer to the following figure which contains drafts of a context and level-0 DFD for a University class CHAPTER 7 STRUCTURING SYSTEM PR TABLE 7-2 Rules Governing Data Flow Diagramming Process: A. No process can have only outputs. It would be making data from nothing (a miracle). If an object has only outputs, then it must be a source B. No process can have only inputs (a black hole). If an object has only inputs, then it must be a sink C. A process has a verb phrase label. Data Store: D. Data cannot move directly from one data store to another data store. Data must be moved by a process. E. Data cannot move directly from an outside source to a data store. Data must be moved by a process that receives data from the source and places the data into the data store F. Data cannot move directly to an outside sink from a data store. Data must be moved by a process. G. A data store has a noun phrase label. Source/Sink: H. Data cannot move directly from a source to a sink. It must be moved by a process if the data are of any concern to our system. Otherwise, the data flow is not shown on the DFD 1. A source/sink has a noun phrase label. Data Flow: J. A data flow has only one direction of flow between symbols. It may flow in both directions between a process and a data store to show a read before an update. The latter is usually indicated, however, by two separate arrows because these happen at different times. K. A fork in a data flow means that exactly the same data goes from a common location to two or more different processes, data stores, or sources/sinks (this usually indicates different copies of the same data going to different locations). L. A join in a data flow means that exactly the same data come from any of two or more different processes, data stores, or sources/sinks to a common location. M. A data flow cannot go directly back to the same process it leaves. There must be at least one other process that handles the data flow, produces some other data flow, and returns the original data flow to the beginning process. N. A data flow to a data store means update (delete or change). 0. A data flow from a data store means retrieve or use. P. A data flow has a noun phrase label. More than one data flow noun phrase can appear on a single arrow as long as all of the flows on the same arrow move together as one package. (Source: Based on Celko, 1987.) Guidelines for Drawing DFDs In this section, we will consider additional guidelines for drawing DFDs that extend berond the simple mechanics of drawing diagrams and making sure that the rules listed in Tables 7-2 and 7-3 are followed. These guidelines include (1) completeness, (2) consistency, (3) timing considerations, (4) the iterative nature of drawing DFDs, and (5) primitive DFDs. Completeness The concept of DFD completeness refers to whether you have included in your DFDs all of the components necessary for the system you are modeling. If your DFD contains data flows that do not lead anywhere o.
Data Warehouse:
A physical repository where relational data are specially organized to provide enterprise-wide, cleansed data in a standardized format.
Reconciled data: detailed, current data intended to be the single, authoritative source for all decision support.
Extraction:
The Extract step covers the data extraction from the source system and makes it accessible for further processing. The main objective of the extract step is to retrieve all the required data from the source system with as little resources as possible.
Data Transformation:
Data transformation is the component of data reconcilation that converts data from the format of the source operational systems to the format of enterprise data warehouse.
Data Loading:
During the load step, it is necessary to ensure that the load is performed correctly and with as little resources as possible. The target of the Load process is often a database. In order to make the load process efficient, it is helpful to disable any constraints and indexes before the load and enable them back only after the load completes. The referential integrity needs to be maintained by ETL tool to ensure consistency.
A graphical tool, useful for communicating with users, managers, and other personnel.
Used to perform structured analysis to determine logical requirements.
Useful for analyzing existing as well as proposed systems.
Focus on the movement of data between external entities and processes, and between processes and data stores.
A relatively simple technique to learn and use.
Java Developers, make the database work for you (NLJUG JFall 2010)Lucas Jellema
The general consensus among Java developers has evolved from a dogmatic strive for database independence to a much more pragmatic wish to leverage the power of the database. This session demonstrates some of the (hidden) powers of the database and how these can be utilized from Java applications using either straight JDBC or working through JPA. The Oracle database is used as example: SQL for Aggregation and Analysis, Flashback Queries for historical comparison and trends, Virtual Private Database, complex validation, PL/SQL and collections for bulk data manipulation, view and instead-of triggers for data model morphing, server push of relevant data changes, edition based redefinition for release management.
- overview of role of database in JEE architecture (and a little history on how the database is perceived through the years)
- discussion on the development of database functionality
- demonstration of some powerful database features
- description of how we leveraged these features in our JSF (RichFaces)/JPA (Hibernate) application
- demo of web application based on these features
- discussion on how to approach the database
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Refer to the following figure which contains drafts of a context and l.docxlmarie40
Refer to the following figure which contains drafts of a context and level-0 DFD for a University class CHAPTER 7 STRUCTURING SYSTEM PR TABLE 7-2 Rules Governing Data Flow Diagramming Process: A. No process can have only outputs. It would be making data from nothing (a miracle). If an object has only outputs, then it must be a source B. No process can have only inputs (a black hole). If an object has only inputs, then it must be a sink C. A process has a verb phrase label. Data Store: D. Data cannot move directly from one data store to another data store. Data must be moved by a process. E. Data cannot move directly from an outside source to a data store. Data must be moved by a process that receives data from the source and places the data into the data store F. Data cannot move directly to an outside sink from a data store. Data must be moved by a process. G. A data store has a noun phrase label. Source/Sink: H. Data cannot move directly from a source to a sink. It must be moved by a process if the data are of any concern to our system. Otherwise, the data flow is not shown on the DFD 1. A source/sink has a noun phrase label. Data Flow: J. A data flow has only one direction of flow between symbols. It may flow in both directions between a process and a data store to show a read before an update. The latter is usually indicated, however, by two separate arrows because these happen at different times. K. A fork in a data flow means that exactly the same data goes from a common location to two or more different processes, data stores, or sources/sinks (this usually indicates different copies of the same data going to different locations). L. A join in a data flow means that exactly the same data come from any of two or more different processes, data stores, or sources/sinks to a common location. M. A data flow cannot go directly back to the same process it leaves. There must be at least one other process that handles the data flow, produces some other data flow, and returns the original data flow to the beginning process. N. A data flow to a data store means update (delete or change). 0. A data flow from a data store means retrieve or use. P. A data flow has a noun phrase label. More than one data flow noun phrase can appear on a single arrow as long as all of the flows on the same arrow move together as one package. (Source: Based on Celko, 1987.) Guidelines for Drawing DFDs In this section, we will consider additional guidelines for drawing DFDs that extend berond the simple mechanics of drawing diagrams and making sure that the rules listed in Tables 7-2 and 7-3 are followed. These guidelines include (1) completeness, (2) consistency, (3) timing considerations, (4) the iterative nature of drawing DFDs, and (5) primitive DFDs. Completeness The concept of DFD completeness refers to whether you have included in your DFDs all of the components necessary for the system you are modeling. If your DFD contains data flows that do not lead anywhere o.
Data Warehouse:
A physical repository where relational data are specially organized to provide enterprise-wide, cleansed data in a standardized format.
Reconciled data: detailed, current data intended to be the single, authoritative source for all decision support.
Extraction:
The Extract step covers the data extraction from the source system and makes it accessible for further processing. The main objective of the extract step is to retrieve all the required data from the source system with as little resources as possible.
Data Transformation:
Data transformation is the component of data reconcilation that converts data from the format of the source operational systems to the format of enterprise data warehouse.
Data Loading:
During the load step, it is necessary to ensure that the load is performed correctly and with as little resources as possible. The target of the Load process is often a database. In order to make the load process efficient, it is helpful to disable any constraints and indexes before the load and enable them back only after the load completes. The referential integrity needs to be maintained by ETL tool to ensure consistency.
A graphical tool, useful for communicating with users, managers, and other personnel.
Used to perform structured analysis to determine logical requirements.
Useful for analyzing existing as well as proposed systems.
Focus on the movement of data between external entities and processes, and between processes and data stores.
A relatively simple technique to learn and use.
Java Developers, make the database work for you (NLJUG JFall 2010)Lucas Jellema
The general consensus among Java developers has evolved from a dogmatic strive for database independence to a much more pragmatic wish to leverage the power of the database. This session demonstrates some of the (hidden) powers of the database and how these can be utilized from Java applications using either straight JDBC or working through JPA. The Oracle database is used as example: SQL for Aggregation and Analysis, Flashback Queries for historical comparison and trends, Virtual Private Database, complex validation, PL/SQL and collections for bulk data manipulation, view and instead-of triggers for data model morphing, server push of relevant data changes, edition based redefinition for release management.
- overview of role of database in JEE architecture (and a little history on how the database is perceived through the years)
- discussion on the development of database functionality
- demonstration of some powerful database features
- description of how we leveraged these features in our JSF (RichFaces)/JPA (Hibernate) application
- demo of web application based on these features
- discussion on how to approach the database
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
2. Systems Analysis
• Focus is the logical view of the
system, not the physical
• “What” the system is to accomplish,
not how
• Tools:
–data flow diagrams
–data dictionary
–process specification
–entity-relationship diagrams
3. Data Flow Diagram:
"a network representation of a system.
The system may be automated, manual,
or mixed. The DFD portrays the system
in terms of its component pieces, with all
interfaces among the components
indicated."
- Tom DeMarco
hence DFDs:
focus on the movement of data between
external entities and processes, and
between processes and data stores
5. Data Flow Diagrams are:
• Used to perform structured analysis
to determine logical requirements
• A graphical tool, useful for
communicating with users,
managers, and other IS personnel
• Useful for analyzing existing as well
as proposed systems
• A relatively simple technique to learn
and use
6. Why Conduct Process
Modeling?
• Understand components of
current logical or physical
system for purpose of rebuilding
in a different physical
form/technology, possibly with
some changed functionality
• Find inefficiencies in current
system
• Re-engineer current system
7. Sources/Sinks
(external entities)
• Any class of people, an
organization, or another
system which exists
outside the system you
are studying.
• Form the boundaries of
the system.
• The system and external
entities exchange data in
the form of data flows.
• Must be named, titles
preferred to names of
individuals - use a noun
source
/
sink
8. Data Flows
• data in motion
• marks movement of data through the
system - a pipeline to carry data
• connects the processes, external
entities and data stores
• Unidirectional
• originate OR end at a process (or both)
• name as specifically as possible -
reflect the composition of the data - a
noun
• do not show control flow! Control flow
is easy to identify- a signal with only
one byte - (on/off).
• HINT: if you can't name it: either it's
control flow, doesn't exist or you need
to get more information!
9. Processes
• transform incoming data
flows into outgoing data
flows
• represent with a bubble or
rounded square
• name with a strong
VERB/OBJECT
combination; examples:
create_exception_report
validate_input_characters
calculate_discount
process
10. Data Stores
• data at rest
• represents holding areas for
collection of data, processes
add or retrieve data from
these stores
• name using a noun (do not
use ‘file’)
• only processes are connected
to data stores
• show net flow of data
between data store and
process. For instance, when
access a DBMS, show only
the result flow, not the
request
data store
11. Data Flow Diagram Don’ts
1. BLACK HOLES
2. MIRACLES
3. Let it get too COMPLEX: 7 ± 2 processes
4. Leave things UNLABELED
(corollary: labels should have meaning)
5. Data stores that are “SOURCES” or
“SINKS”
6. Data flows that are UNASSOCIATED with
a PROCESS
7. Expect your diagram to be “perfect” the
first time!
12. Data Flow Diagram Don’ts
process
stuff
1. ‘Black Hole’
process
stuff
2. ‘It’s a Miracle’
13. Data Flow Diagram Don’ts
A.2
A.1
ds-1
data
4. Leave Things Unlabeled
Corollary: Labels Should
Have Meaning
14. Data Flow Diagram Don’ts
data store 5. Miracle data
source
data store
5. Black hole data
source
15. Data Flow Diagram Don’ts
6. Data Flows Unassociated With a Process
entity to
entity
data store
to entity -
or reverse
data store
to data
store
16. Diagramming A System
• multiple DFDs are required to
represent a system
• DFDs are created at increasing
levels of detail
17. Different Types of DFDs
• Context diagram
• Level-0 diagram (system diagram)
• Level-n diagram
• Primitive diagram
18. Context Diagram
• defines the scope of the system by
identifying the system boundary
• contains:
–one process (which represents the
entire system)
–all sources/sinks (external
entities)
–data flows linking the process to
the sources and sinks (external
entities)
20. Constructing a Context
Diagram
• identify and list sources/sinks
(external entities)
• identify and list inputs to and
outputs from sources/sinks
(external entities)
• create context diagram
21. Level-0 Diagram
• describes the overall processing of the
system
• show one process for each major
processing step or functional
requirement
• data flows from the context appear on
system diagram also (level balancing)
• can show a single data store to
represent all data in aggregate at this
level
• can draw duplicate sources, sinks and
data stores to increase legibility
22. Drawing a Level-0 Diagram
• list the major data stores
• list major business steps
• draw a segment for each business
step
• assemble into single DFD
• re-organize until satisfied
• number processes
23. Functional Decomposition
• similar to a series of more detailed maps
• iterative process of breaking the
description of a system into finer and
finer detail to create a set of charts in
which one process on a given chart is
explained in greater detail on another
chart
• referred to as exploding, partitioning, or
leveling
• must use your judgment to decide what
goes on each level
• show error and exception handling on
lower levels (if at all)
24. Lower Level Diagrams
• explode the processes shown on the
level-0 diagram
• each process is represented by its own
DFD
• balance data
– data flows on upper level appear on
lower level, or
– data flows on upper level are broken into
component pieces with components
shown on lower level
• each lower level shows greater and
greater detail
• follow numbering convention
25. Balancing DFDs
• conserve data from level to level -
inputs and outputs on the higher
level must appears somewhere on
the lower level
26. Advanced Rules
• Composite data flow on one level can be
split into its component data flows on
the next level - but new data cannot be
added and all data in the composite
must be included in the sub-flows
• The inputs to a process must be
sufficient to produce the outputs.
• Lowest level DFDs may add new data
flows to represent exception handling,
i.e., error messages
• May repeat data stores or sources/sink
to avoid crossing lines
27. Additional Guidelines
• the inputs to a process are different
from the outputs of that process
• objects in a set of DFDs have unique
names
• do not change data flow names on lower
levels unless you are decomposing a
data flow into component pieces.
• never explode a single process into
another single process. If you cannot
partition the process, then the lower
level DFD is not needed.
• expect to iterate, put down the DFD and
go back to it a few times to create
something satisfactory.
28. Other Questions about Lower
level diagrams
1. How deep? (how many levels?)
– if the process has only one input or one
output, probably cannot partition further;
– can you describe the process in English in
about 1/2 page?
2. How broad? (how many processes on a
level?)
– 7 ± two is a reasonable heuristic
– may temporarily place much of the system
on a single diagram then re-draw into
separate levels
29. Quality Guidelines
• Completeness
– all components included & in project
dictionary
• Consistency
– between levels: balancing, leveling
• Timing considerations
– assume system never starts and never
stops
• Iterative nature
– revisions are common
• Drawing primitives (lowest level)
– when to stop?