Structured Walkthrough
January 17, 2008
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The structured Walk-through:
The structured walk through or formal technical review (FTR) is an inspection intended to expose defects in the product. It helps in discovering defects at the earliest possible stage. In addition a walkthrough helps uncover places where standards have been ignored where inefficient algorithms have been used or where a technically correct program might nonetheless present future maintenance problems.
A structured walkthrough is usually a group effort with several people serving different functions on the team. The following are some of the members who participate in a structured walkthrough:
- Presenter
- Coordinator
- Scribe
- Maintenance Critic
- Standard Critic
- One or more user representative.
Roles of each member
The presenter usually the creator of the product leads the team through an examination of the product.
The Coordinator organizes all activities that occur prior to the walkthrough such as seeing that each team member receives copy of the product being examined and also serves as a moderator during the actual review.
The scribe records the proceedings and forwards to management the report summarizing the team findings.
The maintenance critic ascertains that the product performs as requested.
The team members may be analysts and or programmers depending on the type of product being reviewed.
A member may serve several roles e.g. serving as both maintenance and standard critic in order to reduce the size of the team.
The responsibility of the team is to give an accurate appraisal, good or bad of the product being reviewed leading to production of quality system.
The participants should identify defects, but they should not attempt to correct them since the correction is the responsibility of the author.
The outcome of the walkthrough is the walkthrough report prepared by the scribe. On the first page i.e the summary, all participants must sign a report to show that they are in agreement with it. This reinforces the idea of shared responsibility for the quality of the final product.
Data link layer
January 17, 2008
Standards & Protocols
Industry of Electronic and Electrical Engineers (IEEE) split the function of the data link layer into 2 sublayer. They are:
- Media Access Control (MAC)
- Logical Link Control (LLC)
Media Access Control (MAC)
This sublayer defines the way in which multiple NICs share a single transmission medium. It covers:
- Logical topology e.g. bus, ring e.t.c.
- Media Access Method of contention, token passing e.t.c.
- Addressing i.e. the hardware address of the NIC also known as MAC address.
Media Access
This is the methodology used for determining when devices are allowed to communicate using the network. A network has to share the available communications capacity between the various devices that use it. It has to deal with problems such as two devices wanting to communicate simultaneously. This can be done through:
1) Contention
Using this method each network device competes with other connected devices for use of the transmission media. This method brings about collisions, when two devices transmit simultaneously, their signals collide and none is able to transmit.
To reduce collisions, protocols are used to ensure that devices listen to the media before transmitting and only transmit if media is clear. These protocols are called carrier sense multiple access protocols (CSMA). There are two types of CSMA protocols.
Carrier Sense Multiple Access with collision detection (CSMA/CD)
CSMA/CD protocols are capable of detecting a collision and retransmitting the data. They recognize a collision by the excessively high voltage or current when two signals combine. After collision both devices wait for a random period of time before retransmitting e.g. DEC Ethernet Version II and IEEE 802.3
Carrier Sense Multiple Access with collision Avoidance (CSMA/CA)
This protocol uses schemes such as time slices accessing or requests to send data to gain access to the media. e.g. Apples’ Local Talk. Machines wait for the network to be free of traffic before announcing their intention to transmit. If the machine does not receive a negative response, it proceeds to transmit.
Advantages of Contention based:
- Simple low-overhead software.
- Immediate and full control of the media.
Disadvantage of Contention
- Access times are unpredictable
- No prioritizing of devices.
- Collisions increase geometrically as each new device is connected.
Note:
Contention based media access systems provide network access on a first come first serve basis, thus network cards using fast expansion buses such as PCI can place data on the network faster than older ISA type cards and therefore these fast cards can better utilize the network.
The fastest, widest network card available should be put in the servers as these devices are involved in many of the network dialogs between machines.
Some network operating system support multiple network cards per system (multi-homed systems) thus allows the system to access the media faster. This is also known as network load balancing.
2) Token Passing
This method uses a small data frame called token, which is passed from device to device. The first device to join the network creates the token. Any device holding the token has control over the transmission media, and can remove the token and place a data frame on to the media.
The frame passes from device to device until it reaches the destination.The device copies the data and flags the data as read. The token and data continue to pass from device to device until arriving back at the source device.The data is removed and the token is placed back on to the media, which moves onto the next device.
Passing the token around evenly distributes network access among the connected devices. Protocols limit the length of time the token remains with a single device.
Note: Protocols using this system of access control are:
- IEEE 802.5 token ring.
- Future distributed data interface (FODI)
Advantages of Token Passing
- Access times are predictable.
- Data can be prioritized (useful for time-sensitive traffic such as voice or video)
- Collisions can’t occur which allows a higher through put of data under high load conditions.
- One network device is often used as a controller for fault detection and recovery.
Disadvantages of Token Passing
- The software required is more complete and has a higher overhead.
- Some software reconfiguration is required when devices are added or removed.
3) Demand PriorityThis method provides a contention based access method without the risk of collisions. The system requires demand priority switches. These are intelligent switches that control network access and allow only one node to transmit information at a time.
Data can be prioritized depending on the type of data e.g. time sensitive data such as voice and video can be given a high priority which means the switches process it before low priority data. Protocol using these method are IEEE 802.12 known as 100 VG-Any LAN.
Advantage of Demand Priority
- Data can be prioritized – high or low.
- There are no collisions giving a higher throughput of data under high load conditions.
- It supports both Ethernet and token ring type frame, this allows a 100 VG-Any LAN network to be easily connected to another LAN e.g. using a bridge.
Disadvantages of Demand priority
- More complex hardware is required.
- NIC and switches must be purchased.
Leadership
January 5, 2008
Leadership is the process of influencing others to work willingly towards an organizational goal and to the best of their capabilities.
Approaches to the problem of leadership have usually fallen under one of the three general headings.
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Trait theories
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Style theories
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Contingency theories
a) Trait Theories
These have concentrated on finding certain characteristics or traits that effective leaders should posses.
Traits that have been identified include:
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Intelligence
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Initiative i.e. capability to perceive a need for action and the urge to do it.
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Self assurance
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Helicopter Vision i.e. the ability to rise above the particulars of a situation and perceive it in its’ relation to the overall environment.
Other traits include:
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Aggressiveness
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Energy
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A drive for achievement or power
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Appearance
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Imagination
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Decisiveness
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Interpersonal skills
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Integrity
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Sociability
Criticism of Trait Theory
1. Possession of all the traits is an impossible ideal
2. These are too many exceptions i.e. people who don’t have the traits but are notably successful leaders.
3. The top 3 traits are necessary but not sufficient to make a good leaders i.e. possession of them doesn’t make one a good leader.
4.The traits are not well defined to be useful in practice.
b) Style Theory of Leadership
This assumes that employees will work harder for managers who employ given styles than they will for a manager who employs other styles. These styles can are:
- Autocratic
- Paternalistic
- Consultative
- Participative
1.Autocratic Style (Telling style)
In the autocratic style, the manager makes decisions and enforces them. He forces subordinates to work by threatening punishment, penalties. i.e. He coerces the subordinates to work.
Strengths
i. Quick decisions can be made when speed is required
ii. It is the most efficient type of leadership for highly programmed nature work e.g. data processing.
Weaknesses:
i. It does not encourage subordinates to give their opinions when his might be useful.
ii. Communication between manager and subordinates will be one way and the manager will not know until afterwards whether his orders have been properly understood.
iii. It does not encourage initiative and commitments from subordinates.
2.Paternalistic (Sells) type
The manager makes decisions and either announces them to the subordinates.
Strengths
i. Employees are made aware of the reason for decisions.
ii. Selling decisions to staff management make them more willing to cooperate.
iii. Staff will have a better idea of what to do when unforeseen events arise coz the manager will have explained the situation.
Weaknesses:
i. Communication is still largely one way and subordinates might not buy his decisions.
ii. It does not encourage initiative and commitment from subordinates.
3.Consultative Style
In this style the manager may suggest ideas and may ask for comments and amend his decisions accordingly or he may present the problem ask for ideas and make decisions from the ideas.
Strengths
i. Employees are involved in decisions before they are made thus encourages motivation.
ii. An agreed consensus can be reached and for some decisions consensus can be of advantage rather than a work compromise.
iii. Employees can contribute their knowledge and experience to help in solving more complex problems.
Weaknesses:
i. Management takes much longer to make decisions.
ii. Subordinates might be too inexperienced to formulate mature opinions and give practical advices.
4.Participative Style
In this style the leader may present a problem to his group of subordinates and asks them to solve it or he may allow subordinates to acts as they wish within specified limits.
Strengths
i. It can provide high motivation and commitment from employees.
ii. Employees are involved in decisions before they are made thus encourages motivation.
iii. An agreed consensus can be reached and for some decisions consensus can be of advantage rather than a work compromise.
iv. Employees can contribute their knowledge and experience to help in solving more complex problems.
Weaknesses:
i. The authority of the manager may be undermined.
ii. Management takes much longer to make decisions.
iii. Subordinates might be too inexperienced to formulate mature opinions and give practical advices
Authoritarian style is generally referred to as structuring style. Democratic style is usually referred to as supporting style. Supportive style usually leads to:
i. Subordinate satisfaction
ii. Lower turnovers and grievances rates
iii. Less inter-group conflict.
However research findings on democratic style have shown:
a. Productivity increase is not very significant.
b. Some people prefer to be directed
c. In repetitive or routine work a structured style of leadership leads to higher productivity therefore in conclusion overall effectiveness in an organization is clearly dependent on more than style alone.
c)Contingency Theory
This takes more specific account on the other variables involved in a leadership situation. In particular the following:
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Task on hand
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Workgroups
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Position of the leader within that workgroup.
They argue that there is no optimum style but the choice of style will depend on the task on hand and the nature of the group.
Roles & Interaction in organisation
January 5, 2008
Role Theory is a study of individual and his tasks or activities. It seeks to understand how an individual reacts given a particular situation.
The concept of role theory
a)Role set
This is the group of people interacting with the focal person (the subject under consideration) the set includes all those with whom the individual has more than trivial interactions.
b)Role definition
The definition of any individual’s role in any situation will be a combination of the role expectations that the members of the role set have of the focal role. The expectations are often occupationally defined e.g. security officer, lecturer e.t.c.
The particular role at any given time should be clear for example using a role sign.
Roles without signs often lead to confused or defined expectations of the role of the focal person.
c)Role ambiguity
This results when there is some uncertainty in the minds of either the focal person or of the members of his role set as to precisely what his role is at any given time.
d)Role incompatibility
This arises when the expectations of the members of the role set are well known, but are incompatible as features of the same role e.g. the company policy may dictate working mode and subordinate expect independence.
e)Role conflict
This results from the necessity for a person to carry out one or more roles in the same situation.
f)Role Overload
This is the situation where the number of roles that one person has to handle become too much.
g)Role Under-load
This arises when an individual feels that the role definition is out of line with his self concept.
Note:
It is the individual perception that causes role underload.
Role stress
Role ambiguity i.e. unclear role expectations, role incompatibility (i.e. differing expectations), role conflict (i.e. overlapping or conflicting roles), role overload (i.e. too many roles) and role underload (i.e. too few roles) can lead to what is called role stress.
Stress can be good since most people need some form of stress to bring out their best performance. If the stress is of the wrong form or much then it becomes damaging. Beneficial stress is called role pressure, and harmful stress is called role strain.
Symptoms of role strain
a) Tension e.g. irritability
b) Low morale e.g. low confidence in the organization, expression of dissatisfaction with the job e.t.c.
c) Communication difficulties.
If role strained seems to underlie with those behavior patterns, the next step is to identify the types of the role patterns.
Strategies for declining with role strain
The individual can cope with role strain by:
a) Repression
i.e. the individual refuses to admit there is a problem.
b) Withdrawal
i.e. the individual retreats behind a psychological barrier or leaves the organization.
c) Rationalization
The individual decides that the conflict is inevitable and that he must live with it.
Strategies for each type of role problem
a) Role Ambiguity
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Attempt to clarify his/her role definition.
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Enforce his expectations on other members of the role set.
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Asking for clarification other specifically or by precedent from key members of the role set.
b) Role Incompatibility
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Deciding privately to give preference to the more important members of a role set and down grading the expectations of the others.
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By asking for a resolution of the incompatibility from the affected parties.
c) Role Conflict
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By reducing the importance of one of the roles so that performance in that role is no longer a bother to himself.
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Compartmentalization: so that roles do not overlap by setting up roles and procedures to maintain those compartments.
d) Role Overload
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Downgrading the importance of some of the roles.
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By an agreed re-assignment of role responsibilities and priorities.
e) Role underload
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By exercising irritant powers to increase invisibility felt presence in the organization?
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By taking on someone else’s role in addition to your own.
Implication of stress
There are 5 organizational situations that are likely to create role problems and therefore stress for the individual.
a) Responsibility for the work of others
b) Innovative functions: Innovative activities led to conflicting priorities, the organization may be in favor of the states quo and the manager may be at loss as whether to be innovative.
c) Integrative and bonding functions: These are coordinating functions between various groups. There may be inadequate control over their demands for resources.
d) Relationship problems
e) Career uncertainty
