Showing posts with label articles. Show all posts
Showing posts with label articles. Show all posts
Tuesday, 9 July 2013
Monday, 1 July 2013
What is bottom-up implementation - peak concepts
In
a bottom-up implementation, the process is the reverse. The development
starts with implementing the modules at the bottom of the hierarchy and
proceeds through the higher levels until it reaches the top.
What is top down implementation - peak concepts
What is Spiral model - peak concepts
The spiral model is a risk-driven approach to software development that encompasses the best features of both classic life cycle and prototyping. In A quadrant different levels of planning are performed.
In
B quadrant a thorough risk analysis is done and an appropriate
prototype is initiated. In the C quadrant various software development
products are sequentially completed. In the D quadrant client and
management evaluate these products and provide permission to continue
to the next level of the spiral. Spiral goes from A to B, from B to C,
from C to D and from D back to A until the complete system is developed
and accepted.
What is Cohesion - peak concepts
Cohesion:
Cohesion is the concept that tries to capture this intra-module. With
cohesion we are interested in determining how closely the elements of a
module are related to each other. Cohesion of a module represents how
tightly bound the internal elements of the module are to one another.
Cohesion of a module gives the designer an idea about whether the
different elements of a module belong together in the same module.
Cohesion and coupling are clearly related. Usually the greater the
cohesion of each module in the system, the lower the coupling between
modules is. There are several levels of Cohesion:
- Coincidental
- Logical
- Temporal
- Procedural
- Communicational
- Sequential
- Functional
Coincidental
is the lowest level, and functional is the highest. Coincidental
Cohesion occurs when there is no meaningful relationship among the
elements of a module. Coincidental Cohesion can occur if an existing
program is modularized by chopping it into pieces and making different
pieces modules.
What is Coupling - peak concepts
The
more connections between modules, the more dependent they are in the
sense that more knowledge about one module is required to understand or
solve the other module. Hence, the fewer and simpler the connections
between modules, the easier it is to understand one without
understanding the other. Coupling between modules is the strength of
interconnection between modules or a measure of independence among
modules.
To
solve and modify a module separately, we would like the module to be
loosely coupled with other modules. The choice of modules decides the
coupling between modules. Coupling is an abstract concept and is not
easily quantifiable. So, no formulas can be given to determine the
coupling between two modules. However, some major factors can be
identified as influencing coupling between modules.
Among
them the most important are the type of connection between modules, the
complexity of the interface, and the type of information flow between
modules. Coupling increase with the complexity and obscurity of the
interface between modules. To keep coupling low we would like to
minimize the number of interfaces per module and the complexity of each
interface. An interface of a module is used to pass information to and
from other modules. Complexity of the interface is another factor
affecting coupling.
The
more complex each interface is, higher will be the degree of coupling.
The type of information flow along the interfaces is the third major
factor-affecting coupling. There are two kinds of information that can
flow along an interface: data or control, Passing or receiving control
information means that the action of the module will depend on this
control information, which makes it more difficult to understand the
module and provide its abstraction. Transfer of data information means
that a module passes as input some data to another module and gets in
return some data as output.
Characteristics of an SRS - peak concepts
1. Correct
2. Complete
3. Unambiguous
4. Verifiable
5. Consistent
6. Ranked for importance and/or stability
7. Modifiable
8. Traceable
Advantages of SRS - peak concepts
Software SRS establishes the basic for agreement between the client and the supplier on what the software product will do.
1. A SRS provides a reference for validation of the final product.
2. A high-quality SRS is a prerequisite to high-quality software.
3. A high-quality SRS reduces the development cost.
What is SRS - peak concepts
Software
requirement specification (SRS) is a document that completely describes
what the proposed software should do without describing how software
will do it. The basic goal of the requirement phase is to produce the
SRS, Which describes the complete behavior of the proposed software. SRS
is also helping the clients to understand their own needs.
What is Error Correction and Detection - peak concepts
Error Correction : Send
additional information so incorrect data can be corrected and accepted.
Error correction is the additional ability to reconstruct the original,
error-free data.
There are two basic ways to design the channel code and protocol for an error correcting system :
• Automatic Repeat-Request (ARQ) : The
transmitter sends the data and also an error detection code, which the
receiver uses to check for errors, and request retransmission of
erroneous data. In many cases, the request is implicit; the receiver
sends an acknowledgement (ACK) of correctly received data, and the
transmitter re-sends anything not acknowledged within a reasonable
period of time.
• Forward Error Correction (FEC) : The
transmitter encodes the data with an error-correcting code (ECC) and
sends the coded message. The receiver never sends any messages back to
the transmitter. The receiver decodes what it receives into the "most
likely" data. The codes are designed so that it would take an
"unreasonable" amount of noise to trick the receiver into
misinterpreting the data.
What is a Connection-Oriented Service - peak concepts
- In connection oriented service a connection is established between the communicating n+1entity using the service provided by the n-entity.
- The service users of connection oriented service undergo three different phases.
- Connection oriented service is modeled after the telephone system. When we make a phone call, we first establish a connection; then we talk or transfer information. And when we are done we hang up or drop the connection.
- Such a connection acts like a tube. The sender pushes bits from one end of the tube and the receive takes out from the other end.
- In connection oriented service, the order in which the bits are received is same as the order in which they are sent.
- During connection establishment, the sender, receiver and subnet negotiate certain parameters as quality of service required, maximum message size, and exchange of source and destination addresses.
Sunday, 30 June 2013
Disadvantages of Hybrid Network - peak concepts
- Users may need to remember multiple passwords.
- Files can be duplicated and changes overwritten between the computers with the shared folder and the Server.
- Files saved on the workstation are not backed up.
Advantages of Hybrid Network - peak concepts
- Client Server application are still centrally located and managed.
- Users can assign local access to resources in their computers.
- Workgroups can manage resources without requiring assistance from network administrator.
What is Hybrid networks - peak concepts
- Hybrid networks are the networks that are based on both peer-to-peer & client-server relationship.
- Hybrid networks incorporate the best features of workgroups in peer-to-peer networks with the performance, security and reliability of server-based networks.
- Hybrid networks still provide all of the centralized services of servers, but they also allow users to share and manage their own resources within the workgroup.
What is packet - peak concepts
Disadvantages of Peer to Peer Networks - peak concepts
1.
In peer-to-peer network, the absence of centralized server make it
difficult to backup data as data is located on different workstations.
2. Security is weak as each system manages itself only.
3. There is no central point of data storage for file archiving.
What is Peer-to-Peer Networks - peak concepts
- In the peer to peer computer network model we simply use the same Workgroup for all the computers and a unique name for each computer in a computer network.
- There is no master or controller or central server in this computer network and computers join hands to share files, printers and Internet access.
- It is practical for workgroups of a dozen or less computers making it common environments, where each PC acts as an independent workstation and maintaining its own security that stores data on its own disk but which can share it with all other PCs on the network.
- Software for peer-to-peer network is included with most modern desktop operating systems such as Windows and Mac OS.
- Peer to peer relationship is suitable for small networks having less than 10 computers on a single LAN.
What is Internet - peak concepts
What is Intranet - peak concepts
Intranet : An intranet is a set of interconnected networks or Internetworking, using the Internet Protocol and uses IP-based tools such as web browsers and ftp tools, that is under the control of a single administrative entity.
That administrative entity closes the intranet to the rest of the
world, and allows only specific users. Most commonly, an intranet is the
internal network of a company or other enterprise. A large intranet
will typically have its own web server to provide users with browseable information.
What is Extranet - peak concepts
