- The way in which the connections are made (shape of network) is called topology of network.
- Geometric representation of the relationship of all the links and linking devices.
* Network topology
- Refers to physical layout of the network, the location of the computer and how cable is run between them.
* Physical topologies: describe how the cables are run.
* Logical topologies: describe how the network messages travel.
* Types Of Physical Topology
- The software is different from other products in terms of its special characteristic that it does not wear out.
1. Software does not wear out
- In the initial phase (burn-in phase), the failure rate is high.
- When we start testing the product, we detect faults.
- These faults are corrected which results into a drop in the failure rate.
- The second phase where the failure rate is more or less constant is called useful life of any product.
- After the completion of the useful life phase, the failure rate again increases due to the effects of environmental conditions
- Various parts begin to wear-out phase.
- This phase is called wear We do not have the wear-out phase in software.
- As the testing progresses, many failures are experienced and the required corrective actions are preformed to remove faults
- Software may become obsolete( outdated) due to following reasons technologies, change in expectations, poor response time, deterioration in the structure of the source code, complexity issues, etc.
2. Flexibility of software
According to stakeholder flexibility means
- Making changes
- Add new features or functionalities
- Modify source code
- Managing complexity
- Any changes possible at any time without much difficulty.
- Modify software is easy but mange the effect of change is difficult.
- Add new feature making difficulty to developer
- All changes must be made after proper other parts of source code.
3. Reusability of software
- The reusable component are very common and popular in practice and also reduce the cost of manufacturing although maintaining the quality standard.
- Each customer have unique requirement and expectations.
- Software reusability means integrate all well tested component in new software under development.
- Advantage: software development and testing cost are reduced.
- Use the concept of object-oriented analysis and design to make it an independent piece of software which can easily be plugged into other software.
- To make an effective, reliable, efficient software for the customers.
- To produce libraries of standard software components this can easily be integrated in order to produce a good quality product in time and within budget.
- Microsoft Foundation Classes (MFC), Commercially off-the-shelf (COTS) component
- It is point to point connection with only the two devices on either side of it.
- Signal passed along the ring in one direction, from device to device until it reaches its destination.
- Each device in ring communicate with repeater (repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances).
- The ring topology is continues path for data with no logical beginning or ending point and thus no terminators.
- Network may be either unidirectional or bidirectional.
Advantages of ring topology
It is easy to install and configure.
Every computer is given equal access to the ring. No single computer can monopolies the network.
Disadvantage of ring topology
Failure in any cable or node breaks the loop and can take down the entire network.
Maximum ring length and number of nodes are limited.
- Data are represented in form of bit.E.g. 0 , 1.
- Different bit pattern is known as code.
- Todayâ€™s codding system in Unicode 32 bit.
- Numbers are also represented in bit format.
- Number is directly converted into binary number.
- It is represented in form of matrix of pixel.
- It is continues data. - Used to recording or broadcasting of sound or music.
o It provides a clear representation of iterations and overlapping phases.
o The model emphasizes the reusability of the source code.
o The circles depict the overlapping phases.
o The arrows within circles depicts iterations within the phases.
o Changes can be easily made between class specification and requirement specification.
o So no need to freeze the requirements in the early phases of software developmen.
o System is developed in terms of classes.
o Phases can be applied to individual classes.
- Overlapping phases
- Short maintenance cycle
- Can easily accommodate changing
- Supports reusability
- Undisciplined software development approach in which the developer moves randomly between phases.