The economic value of an RSC lies in its ability to do three things:. This educational value is provided in the form of written guidance and tests that help the integrator assimilate their applications on top of the LynxOS RSC in a timely manner. This learning economy can be consistently applied in future projects. The RSC concept avoids this dilemma by focusing the engineering and auditing effort on software integration, not previously verified operating system functions such as message queues.
This risk economy can be consistently applied in future projects. The effort to verify a time- and space-partitioned operating system of this size is tens of person-years of effort. This yields higher quality for a reused component than would be the case for a component that is de- veloped and used only once. Similarly, how do you reuse codes? See 10 tips on writing reusable code for some help.
Keep the code DRY. Write unit tests for your classes AND make it easy to test classes. Remove the business logic or main code away from any framework code.
Try to think more abstractly and use Interfaces and Abstract classes. System reuse : Complete systems , which may include several application programs. Application reuse : An application may be reused either by incorporating it without change into other or by developing application families. Component reuse : Components of an application from sub- systems to single objects may be reused. Code reuse aims to save time and resources and reduce redundancy by taking advantage of assets that have already been created in some form within the software product development process.
In programming, reusable code is the use of similar code in multiple functions. No, not by copying and then pasting the same code from one block to another and from there to another and so on. Instead, code reusability defines the methodology you can use to use similar code , without having to re-write it everywhere. Reusable components add standardized interfaces and object introspection mechanisms to widgets allowing builder tools to query components about their properties and behavior.
Software components need not be visible in a running application; they only need to be visible when the application is constructed. According to Rine and Nada , requirements reuse provides the greatest improvement as regards productivity, quality and time-to-market in between the different software reuse activities that can be performed throughout the software development life cycle.
The concept of reusability is widely used in order to reduce cost, effort, and time of software development. Reusability also increases the productivity, maintainability, portability, and reliability of the software products. That is the reusable software components are evaluated several times in other systems before. Software maintenance in software engineering is the modification of a software product after delivery to correct faults, to improve performance or other attributes.
A common perception of maintenance is that it merely involves fixing defects. Lower development costs: Development costs are proportional to the size of the software being developed. Reusing software means that fewer lines of code have to be written. Reduced process risk: The cost of existing software is already known, whereas the costs of development are always a matter of judgment. This is an important factor for project management because it reduces the margin of error in project cost estimation.
This is particularly true when relatively large software components such as subsystems are reused. Standards compliance: Some standards, such as user interface standards, can be implemented as a set of reusable components. For example, if menus in a user interface are implemented using reusable components, all applications present the same menu formats to users.
The use of standard user interfaces improves dependability because users make fewer mistakes when presented with a familiar interface. Problems with software reuse: Creating, maintaining, and using a component library: Populating a reusable component library and ensuring the software developers can use this library can be expensive. Development processes have to be adapted to ensure that the library is used.
Finding, understanding, and adapting reusable components: Software components have to be discovered in a library, understood and, sometimes, adapted to work in a new environment. Engineers must be reasonably confident of finding a component in the library before they include a component search as part of their normal development process. Increased maintenance costs: If the source code of a reused software system or component is not available then maintenance costs may be higher because the reused elements of the system may become increasingly incompatible with system changes.
Lack of tool support: Some software tools do not support development with reuse. It may be difficult or impossible to integrate these tools with a component library system. The software process assumed by these tools may not take reuse into account. This is particularly true for tools that support embedded systems engineering, less so for object-oriented development tools.
Not-invented-here syndrome: Some software engineers prefer to rewrite components because they believe they can improve on them. This is partly to do with trust and partly to do with the fact that writing original software is seen as more challenging than reusing other people's software.
Although reuse is often simply thought of as the reuse of system components, there are many different approaches to reuse that may be used. Reuse is possible at a range of levels from simple functions to complete application systems.
The reuse landscape covers the range of possible reuse techniques. Key factors for reuse planning: The development schedule for the software.
The expected software lifetime. The background, skills and experience of the development team. The criticality of the software and its non-functional requirements. The application domain. The execution platform for the software. Frameworks are moderately large entities that can be reused. They are somewhere between system and component reuse. Frameworks are a sub-system design made up of a collection of abstract and concrete classes and the interfaces between them.
The sub-system is implemented by adding components to fill in parts of the design and by instantiating the abstract classes in the framework. Application frameworks are moderately large entities that can be reused. Web application frameworks WAF support the construction of dynamic websites as a front-end for web applications.
WAFs are now available for all of the commonly used web programming languages e. Java, Python, Ruby, etc. Interaction model is based on the Model-View-Controller composite design pattern.
An MVC framework supports the presentation of data in different ways and allows interaction with each of these presentations. When the data is modified through one of the presentations, the system model is changed and the controllers associated with each view update their presentation. Dynamic web pages: Classes are provided to help you define web page templates and to populate these dynamically from the system database. Database support: The framework may provide classes that provide an abstract interface to different databases.
Session management: Classes to create and manage sessions a number of interactions with the system by a user are usually part of a WAF.
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