What is CMM(capability maturity model)

What is CMM?

CMM (Capability Maturity Model) is a model of process maturity for software development - an evolutionary model of the progress of a company’s abilities to develop software.

In November 1986, the American Software Engineering Institute (SEI) in cooperation with Mitre Corporation created the Capability Maturity Model for Software.

Development of this model was necessary so that the U.S. federal government could objectively evaluate software providers and their abilities to manage large projects.

Many companies had been completing their projects with significant overruns in schedule and budget. The development and application of CMM helps to solve this problem.

The key concept of the standard is organizational maturity. A mature organization has clearly defined procedures for software development and project management. These procedures are adjusted and perfected as required.

In any software development company there are standards for processes of development, testing, and software application; and rules for appearance of final program code, components, interfaces, etc.

The CMM model defines five levels of organizational maturity:

1. Initial level is a basis for comparison with the next levels. In an organization at the initial level, conditions are not stable for the development of quality software. The results of any project depend totally on the manager’s personal approach and the programmers’ experience, meaning the success of a particular project can be repeated only if the same managers and programmers are assigned to the next project. In addition, if managers or programmers leave the company, the quality of produced software will sharply decrease. In many cases, the development process comes down to writing code with minimal testing.
   
2. Repeatable level. At this level, project management technologies have been introduced in a company. That project planning and management is based on accumulated experience and there are standards for produced software (these standards are documented) and there is a special quality management group. At critical times, the process tends to roll back to the initial level.
   
3. Defined level. Here, standards for the processes of software development and maintenance are introduced and documented (including project management). During the introduction of standards, a transition to more effective technologies occurs. There is a special quality management department for building and maintaining these standards. A program of constant, advanced training of staff is required for achievement of this level. Starting with this level, the degree of organizational dependence on the qualities of particular developers decreases and the process does not tend to roll back to the previous level in critical situations.
   
4. Managed level. There are quantitative indices (for both software and process as a whole) established in the organization. Better project management is achieved due to the decrease of digression in different project indices. However, sensible variations in process efficiency may be different from random variations (noise), especially in mastered areas.
   
5. Optimizing level. Improvement procedures are carried out not only for existing processes, but also for evaluation of the efficiency of newly introduced innovative technologies. The main goal of an organization on this level is permanent improvement of existing processes. This should anticipate possible errors and defects and decrease the costs of software development, by creating reusable components for example.

The Software Engineering Institute (SEI) constantly analyzes the results of CMM usage by different companies and perfects the model taking into account accumulated experience

OSI MODEL

The OSI Reference Model is founded on a suggestion developed by the International Organization for Standardization (ISO). The model is known as ISO OSI (Open Systems Interconnection) Reference Model because it relates with connecting open systems – that is, systems that are open for communication with other systems.
OSI Model is a set of protocols that try to identify and homogenize the data communication practices. The OSI Model has the support of most computer and network vendors, many big customers, and most governments, including the United States.
The OSI Model is a model that illustrates how data communications should take place. It segregates the process into seven groups, called layers. Into these layers are integrated the protocol standards developed by the ISO and other standards organization, including the Institute of Electrical and Electronic Engineers (IEEE), American National Standards Institute (ANSI), and the International Telecommunications Union (ITU), formerly known as the CCITT (Comite Consultatif Internationale de Telegraphique et Telephone). The OSI Model affirms what protocols and standards should be used at each layer. It is modular, each layer of the OSI Model functions with the one above and below it

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