21. In terms of design, what is interface?

1. A user interface, consisting of the set of dials, knobs, operating system commands, graphical display formats, and other devices provided by a computer or a program to allow the user to communicate and use the computer or program. A graphical user interface (GUI) provides its user a more or less "picture-oriented" way to interact with technology. A GUI is usually a more satisfying or user-friendly interface to a computer system.

2. A programming interface, consisting of the set of statements, functions, options, and other ways of expressing program instructions and data provided by a program or language for a programmer to use.

3. The physical and logical arrangement supporting the attachment of any device to a connector or to another device.

Interface design encompasses three distinct, but related constructs--usability, visualization, and functionality

11. What is the real test of a good requirements document?

Correct. Each requirement must accurately describe the functionality to be delivered. The reference for correctness is the source of the requirement, such as an actual customer or a higher-level system requirements specification.

Feasible. It must be possible to implement each requirement within the known capabilities and limitations of the system and its environment.

Necessary. Each requirement should document something the customers really need or something that is required for conformance to an external requirement, an external interface, or a standard.

A good-quality requirement should exhibit the following characteristics that are missing from poorly specified requirements:

• Cohesiveness

• Completeness: Just as an entire requirements specification should be complete and contain all relevant requirements and ancillary material individual requirements should also be complete.

• Consistency

• Correctness: Defects in requirements will naturally lead to corresponding defects in the resulting architectures, designs, and implementations. 

• Currency: All too often, requirements specifications are not updated when requirements change. They are also frequently not updated as the architecture is produced, sometimes resulting in changes in the underlying requirements.

• Customer/User Orientation

• External Observability

• Feasibility

• Lack of Ambiguity

• Mandatory

• Metadata

• Relevance

• Usability

• Validatability

• Verifiability

12.(Context: Source control) Describe branching/merging/ tagging.

Branching in CVS splits a project's development into separate, parallel histories. Changes made on one branch do not affect the other branches. Branching can be used extensively to maintain multiple versions of a product for providing support and new features.

Merging converges the branches back to the main trunk. In a merge, CVS calculates the changes made on the branch between the point where it diverged from the trunk and the branch's tip (its most recent state), then applies those differences to the project at the tip of the trunk.