Software Design

Software Development Process

Software design is the process by which an agent creates a specification of a software artifact, intended to accomplish goals, using a set of primitive components and subject to constraints Software design may refer to either "all the activities involved in conceptualizing, framing, implementing, commissioning, and ultimately modifying complex systems" or "the activity following requirements specification and before programming, as ... a stylized software engineering process." Software design usually involves problem solving and planning a software solution. This includes both low-level component and algorithm design and high-level, architecture design.

Software design is the process of implementing software solutions to one or more set of problems. One of the important parts of software design is the software requirements analysis (SRA). It is a part of the software development process that lists specifications used in software engineering. If the software is "semi-automated" or user centered, software design may involve user experience design yielding a story board to help determine those specifications. If the software is completely automated (meaning no user or user interface), a software design may be as simple as a flow chart or text describing a planned sequence of events. There are also semi-standard methods like Unified Modeling Language and Fundamental modeling concepts. In either case, some documentation of the plan is usually the product of the design. Furthermore, a software design may be platform-independent or platform-specific, depending on the availability of the technology used for the design.

Software design can be considered as creating a solution to a problem in hand with available capabilities. The main difference between Software analysis and design is that the output of a software analysis consist of smaller problems to solve. Also, the analysis should not be very different even if it is designed by different team members or groups. The design focuses on the capabilities, and there can be multiple designs for the same problem depending on the environment that solution will be hosted. They can be operations systems, webpages, mobile or even the new cloud computing paradigm. Sometimes the design depends on the environment that it was developed, whether if it is created from with reliable frameworks or implemented with suitable design patterns). When designing software, two important factors to consider are its security and usability.


Design concepts

The design concepts provide the software designer with a foundation from which more sophisticated methods can be applied. A set of fundamental design concepts has evolved. They are:


Abstraction

Abstraction - Abstraction is the process or result of generalization by reducing the information content of a concept or an observable phenomenon, typically in order to retain only information which is relevant for a particular purpose.


Refinement

Refinement - It is the process of elaboration. A hierarchy is developed by decomposing a macroscopic statement of function in a step-wise fashion until programming language statements are reached. In each step, one or several instructions of a given program are decomposed into more detailed instructions. Abstraction and Refinement are complementary concepts.


Modularity

Modularity - Software architecture is divided into components called modules.


Software Architecture

Software Architecture - It refers to the overall structure of the software and the ways in which that structure provides conceptual integrity for a system. A good software architecture will yield a good return on investment with respect to the desired outcome of the project, e.g. in terms of performance, quality, schedule and cost.


Control Hierarchy

Control Hierarchy - A program structure that represents the organization of a program component and implies a hierarchy of control.


Structural Partitioning

Structural Partitioning - The program structure can be divided both horizontally and vertically. Horizontal partitions define separate branches of modular hierarchy for each major program function. Vertical partitioning suggests that control and work should be distributed top down in the program structure.


Data Structure

Data Structure - It is a representation of the logical relationship among individual elements of data.


Software Procedure

Software Procedure - It focuses on the processing of each modules individually


Information Hiding

Information Hiding - Modules should be specified and designed so that information contained within a module is inaccessible to other modules that have no need for such information


Design considerations

There are many aspects to consider in the design of a piece of software. The importance of each should reflect the goals the software is trying to achieve. Some of these aspects are:

Compatibility

The software is able to operate with other products that are designed for interoperability with another product. For example, a piece of software may be backward-compatible with an older version of itself.

Extensibility

New capabilities can be added to the software without major changes to the underlying architecture.

Fault-tolerance

The software is resistant to and able to recover from component failure.

Maintainability

A measure of how easily bug fixes or functional modifications can be accomplished. High maintainability can be the product of modularity and extensibility.

Modularity

The resulting software comprises well defined, independent components. That leads to better maintainability. The components could be then implemented and tested in isolation before being integrated to form a desired software system. This allows division of work in a software development project.

Reliability

The software is able to perform a required function under stated conditions for a specified period of time.

Reusability

The software is able to add further features and modification with slight or no modification.

Robustness

The software is able to operate under stress or tolerate unpredictable or invalid input. For example, it can be designed with a resilience to low memory conditions.

Security

The software is able to withstand hostile acts and influences.

Usability

The software user interface must be usable for its target user/audience. Default values for the parameters must be chosen so that they are a good choice for the majority of the users.--164.100.96.254 (talk) 11:05, 6 April 2013 2020 (UTC)

Performance

The software performs its tasks within a user-acceptable time. The software does not consume too much memory.

Scalability

The software adapts well to increasing data or number of users.



Tools and Technologies


User experience design and interactive design

Users understanding the content of a website often depends on users understanding how the website works. This is part of the user experience design. User experience is related to layout, clear instructions and labeling on a website. How well a user understands how they can interact on a site may also depend on the interactive design of the site. If a user perceives the usefulness of that website, they are more likely to continue using it. Users who are skilled and well versed with website use may find a more unique, yet less intuitive or less user-friendly website interface useful nonetheless. However, users with less experience are less likely to see the advantages or usefulness of a less intuitive website interface. This drives the trend for a more universal user experience and ease of access to accommodate as many users as possible regardless of user skill. Much of the user experience design and interactive design are considered in the user interface design.

Page layout

Part of the user interface design is affected by the quality of the page layout. For example, a designer may consider if the sites page layout should remain consistent on different pages when designing the layout. Page pixel width may also be considered vital for aligning objects in the layout design. The most popular fixed-width websites generally have the same set width to match the current most popular browser window, at the current most popular screen resolution, on the current most popular monitor size. Most pages are also center-aligned for concerns of aesthetics on larger screens.

Fluid layouts

Fluid layouts increased in popularity around 2000 as an alternative to HTML-table-based layouts and grid-based design in both page layout design principle, and in coding technique, but were very slow to be adopted.[note 1] This was due to considerations of screen reading devices and windows varying in sizes which designers have no control over. Accordingly, a design may be broken down into units (sidebars, content blocks, embedded advertising areas, navigation areas) that are sent to the browser and which will be fitted into the display window by the browser, as best it can. As the browser does recognize the details of the reader's screen (window size, font size relative to window etc.) the browser can make user-specific layout adjustments to fluid layouts, but not fixed-width layouts. Although such a display may often change the relative position of major content units, sidebars may be displaced below body text rather than to the side of it. This is a more flexible display than a hard-coded grid-based layout that doesn't fit the device window. In particular, the relative position of content blocks may change while leaving the content within the block unaffected. This also minimizes the user's need to horizontally scroll the page.

Responsive Web Design

Responsive Web Design is a newer approach, based on CSS3, and a deeper level of per-device specification within the page's stylesheet through an enhanced use of the CSS @media pseudo-selector.

Typography

Web designers may choose to limit the variety of website typefaces to only a few which are of a similar style, instead of using a wide range of typefaces or type styles. Most browsers recognize a specific number of safe fonts, which designers mainly use in order to avoid complications. Font downloading was later included in the CSS3 fonts module and has since been implemented in Safari 3.1, Opera 10 and Mozilla Firefox 3.5. This has subsequently increased interest in web typography, as well as the usage of font downloading. Most layouts on a site incorporate negative space to break the text up into paragraphs and also avoid center-aligned text.

Motion graphics

The page layout and user interface may also be affected by the use of motion graphics. The choice of whether or not to use motion graphics may depend on the target market for the website. Motion graphics may be expected or at least better received with an entertainment-oriented website. However, a website target audience with a more serious or formal interest (such as business, community, or government) might find animations unnecessary and distracting if only for entertainment or decoration purposes. This doesn't mean that more serious content couldn't be enhanced with animated or video presentations that is relevant to the content. In either case, motion graphic design may make the difference between more effective visuals or distracting visuals.

Quality of code

Website designers may consider it to be good practice to conform to standards. This is usually done via a description specifying what the element is doing. Failure to conform to standards may not make a website unusable or error prone, but standards can relate to the correct layout of pages for readability as well making sure coded elements are closed appropriately. This includes errors in code, more organized layout for code, and making sure IDs and classes are identified properly. Poorly-coded pages are sometimes colloquially called tag soup. Validating via W3C[7] can only be done when a correct DOCTYPE declaration is made, which is used to highlight errors in code. The system identifies the errors and areas that do not conform to web design standards. This information can then be corrected by the user.

Quality Service

“Quality in a service or product is not what you put into it. It is what the client or customer gets out of it.” – Peter Drucker

Productivity & Efficiency

“Productivity and efficiency can be achieved only step by step with sustained hard work, relentless attention to details and insistence on the highest standards of quality and performance.” - J. R. D. Tata

Strong Determination

”An invincible determination can accomplish almost anything and in this lies the great distinction between great men and little men.” --Thomas Fuller

Experience

"Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't." -- Pete Seeger

Good Judgement

"Good judgment comes from experience, and experience comes from bad judgment." --Barry LePatner

Create Success

"The majority of men meet with failure because of their lack of persistence in creating new plans to take the place of those which fail.” --Napoleon Hill



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