Weekend Gateaway to Nimpith - Kaikhali

UML Notes

Links to UML PDF:

https://docs.google.com/file/d/0B-n1lqqGWToXbFRFWmZmNFpSYUE/edit?usp=sharing

https://docs.google.com/file/d/0B-n1lqqGWToXeEU4b3RmRlFWQTQ/edit?usp=sharing

Transit of Venus

credits: Michel Breitfellner and Miguel Perez Ayucar/ESAC

3rd International Conference

Technical and Managerial Innovation in Computing and Communications in Industry and Academia

Venue : Science City, Kolkata
Date : 18th -19th August, 2012
Conference URL: www.iem.edu.in/conference

Theme of the Conference
Innovative Ideas in National Skill Development vis-à-vis International Scenario

Innovative ideas in bridging skill gap and providing trained manpower to various diversified service sectors of the country are the need of the hour. These may be achieved through various national skill development programs and job oriented structured courses that strive towards building a formidable work force of international quality and standard in IT, ITES, Telecom, Finance, Banking, Retail, Manufacturing, Insurance, Infrastructure industries and the like that use technical and managerial approaches.

Innovation is the creation of better or more effective products, processes, services, technologies, or ideas that are accepted by markets, governments, and society. Innovation differs from invention in that innovation refers to the use of a new idea or method, whereas invention refers more directly to the creation of the idea or method itself.

Innovation matters. It is a key characteristic associated with the success of any society. Innovation is exploring new ideas based on existing technologies. The continuous improvement and advancement of the previously known technologies can result in developing new products, processes and systems which improves the quality of life for the society as the whole.

Managing innovation consists of:

Identifying the opportunity for innovation
Setting the objectives and benefits
Background research and generating creative idea(s)
Feasibility and risk factors analysis
Design, development, prototypes and testing
Policies and strategies of new procedures and managements
Market research and analysis
Implementation

For organizations that are competing globally, innovation is the key for survival. Technological innovation requires a change in processes and how companies do business. As an example, manufacturing industry has been changing radically in order to reduce costs and waste, increase variety and improve productivity. Technological innovation is a must to maintain global competitiveness.

Important Dates
Paper Submission: 15^th June, 2012
Acceptance Notification: 7^th July, 2012
Camera Ready Paper Submission: 15^th July, 2012

Paper Submission Link: https://www.easychair.org/account/signin.cgi?conf=tmiccia2012

PERT Important Points

PERT

Complex projects require a series of activities, some of which must be performed sequentially and others that can be performed in parallel with other activities. This collection of series and parallel tasks can be modeled as a network.

In 1957 the Critical Path Method (CPM) was developed as a network model for project management. CPM is a deterministic method that uses a fixed time estimate for each activity. While CPM is easy to understand and use, it does not consider the time variations that can have a great impact on the completion time of a complex project.

The Program Evaluation and Review Technique (PERT) is a network model that allows for randomness in activity completion times. PERT was developed in the late 1950's for the U.S. Navy's Polaris project having thousands of contractors. It has the potential to reduce both the time and cost required to complete a project.

The Network Diagram

In a project, an activity is a task that must be performed and an event is a milestone marking the completion of one or more activities. Before an activity can begin, all of its predecessor activities must be completed. Project network models represent activities and milestones by arcs and nodes. PERT originally was an activity on arc network, in which the activities are represented on the lines and milestones on the nodes. Over time, some people began to use PERT as an activity on node network. For this discussion, we will use the original form of activity on arc.

The PERT chart may have multiple pages with many sub-tasks. The following is a very simple example of a PERT diagram:

PERT Chart

The milestones generally are numbered so that the ending node of an activity has a higher number than the beginning node. Incrementing the numbers by 10 allows for new ones to be inserted without modifying the numbering of the entire diagram. The activities in the above diagram are labeled with letters along with the expected time required to complete the activity.

Steps in the PERT Planning Process

PERT planning involves the following steps:

1. Identify the specific activities and milestones.
2. Determine the proper sequence of the activities.
3. Construct a network diagram.
4. Estimate the time required for each activity.
5. Determine the critical path.
6. Update the PERT chart as the project progresses.

1.  Identify Activities and Milestones

The activities are the tasks required to complete the project. The milestones are the events marking the beginning and end of one or more activities. It is helpful to list the tasks in a table that in later steps can be expanded to include information on sequence and duration.

2.  Determine Activity Sequence

This step may be combined with the activity identification step since the activity sequence is evident for some tasks. Other tasks may require more analysis to determine the exact order in which they must be performed.

3.  Construct the Network Diagram

Using the activity sequence information, a network diagram can be drawn showing the sequence of the serial and parallel activities. For the original activity-on-arc model, the activities are depicted by arrowed lines and milestones are depicted by circles or "bubbles".

If done manually, several drafts may be required to correctly portray the relationships among activities. Software packages simplify this step by automatically converting tabular activity information into a network diagram.

4.  Estimate Activity Times

Weeks are a commonly used unit of time for activity completion, but any consistent unit of time can be used.

A distinguishing feature of PERT is its ability to deal with uncertainty in activity completion times. For each activity, the model usually includes three time estimates:

• Optimistic time - generally the shortest time in which the activity can be completed. It is common practice to specify optimistic times to be three standard deviations from the mean so that there is approximately a 1% chance that the activity will be completed within the optimistic time.
  
• Most likely time - the completion time having the highest probability. Note that this time is different from the expected time.
  
• Pessimistic time - the longest time that an activity might require. Three standard deviations from the mean is commonly used for the pessimistic time.

PERT assumes a beta probability distribution for the time estimates. For a beta distribution, the expected time for each activity can be approximated using the following weighted average:

Expected time  =  ( Optimistic  +  4 x Most likely  +  Pessimistic ) / 6

This expected time may be displayed on the network diagram.

To calculate the variance for each activity completion time, if three standard deviation times were selected for the optimistic and pessimistic times, then there are six standard deviations between them, so the variance is given by:

[ ( Pessimistic  -  Optimistic ) / 6 ]²

5.  Determine the Critical Path

The critical path is determined by adding the times for the activities in each sequence and determining the longest path in the project. The critical path determines the total calendar time required for the project. If activities outside the critical path speed up or slow down (within limits), the total project time does not change. The amount of time that a non-critical path activity can be delayed without delaying the project is referred to as slack time.

If the critical path is not immediately obvious, it may be helpful to determine the following four quantities for each activity:

• ES - Earliest Start time
• EF - Earliest Finish time
• LS - Latest Start time
• LF - Latest Finish time

These times are calculated using the expected time for the relevant activities. The earliest start and finish times of each activity are determined by working forward through the network and determining the earliest time at which an activity can start and finish considering its predecessor activities. The latest start and finish times are the latest times that an activity can start and finish without delaying the project. LS and LF are found by working backward through the network. The difference in the latest and earliest finish of each activity is that activity's slack. The critical path then is the path through the network in which none of the activities have slack.

The variance in the project completion time can be calculated by summing the variances in the completion times of the activities in the critical path. Given this variance, one can calculate the probability that the project will be completed by a certain date assuming a normal probability distribution for the critical path. The normal distribution assumption holds if the number of activities in the path is large enough for the central limit theorem to be applied.

Since the critical path determines the completion date of the project, the project can be accelerated by adding the resources required to decrease the time for the activities in the critical path. Such a shortening of the project sometimes is referred to as project crashing.

6.  Update as Project Progresses

Make adjustments in the PERT chart as the project progresses. As the project unfolds, the estimated times can be replaced with actual times. In cases where there are delays, additional resources may be needed to stay on schedule and the PERT chart may be modified to reflect the new situation.

Benefits of PERT

PERT is useful because it provides the following information:

• Expected project completion time.
  
• Probability of completion before a specified date.
  
• The critical path activities that directly impact the completion time.
  
• The activities that have slack time and that can lend resources to critical path activities.
  
• Activity start and end dates.

Limitations

The following are some of PERT's weaknesses:

• The activity time estimates are somewhat subjective and depend on judgement. In cases where there is little experience in performing an activity, the numbers may be only a guess. In other cases, if the person or group performing the activity estimates the time there may be bias in the estimate.
  
• Even if the activity times are well-estimated, PERT assumes a beta distribution for these time estimates, but the actual distribution may be different.
  
• Even if the beta distribution assumption holds, PERT assumes that the probability distribution of the project completion time is the same as the that of the critical path. Because other paths can become the critical path if their associated activities are delayed, PERT consistently underestimates the expected project completion time.

The underestimation of the project completion time due to alternate paths becoming critical is perhaps the most serious of these issues. To overcome this limitation, Monte Carlo simulations can be performed on the network to eliminate this optimistic bias in the expected project completion time.

UML: Library Information System

Assignment: Assume that we have identified the following actors and goals:

Actor	Goals	Notes
Librarian	Loan book to patron	Authenticate patron, identify book, mark book as on-loan in catalogue, and add book to list of books on loan to this patron, with a specific due date. If patron's membership has expired, either refuse to lend book or enter "Manage patron information" use case to renew membership.
	Renew book	Identify patron and book, assess fine if overdue, and revise due date. Patron's membership status is checked. Renewal can be done by telephone.
	Process book returned by patron	Identify book, mark as available, and remove from list of books loaned to patron; if book is overdue, assess patron a fine.
	Handle book reported as lost	Identify book, mark as lost, and assess patron a fine.
	Manage patron information	Create, retrieve, update, or delete patron information.
Cataloguer	Process new book	Add new record to online catalogue, or add a copy to an existing record if book is a duplicate.
Patron	Search for a book in the online catalogue	Enter a search string, specifying whether to search for a name, a title, or a subject, to see a list of books matching the search string, then select a book to see the full record for that book; or enter a call number, and see a display of the system record for the specified book.
Administrator	Send overdue book notices.	Request a list of all books that are overdue by more than some minimum number of days.

Note that book ordering and accessions are not currently included in the scope of the automated library information system.

1. Create a UML Use Case Diagram to depict the set of actors and use cases listed above. 

UML Basics

Table of Contents

About UML

UML Elements

Use Case Diagram

Class Diagram

Sequence Diagrams

Collaboration Diagrams

State Diagram

Activity Diagram

Helper Elements

Component Diagrams

Deployment Diagrams

Entity Relationship Diagrams

Extended Entity Relationship (EER) Diagram Concepts

About UML

This chapter will give you a quick overview of the basics of UML. Keep in mind that this is not a comprehensive tutorial on UML but rather a brief introduction to UML which can be read as a UML tutorial. If you would like to learn more about the Unified Modelling Language, or in general about software analysis and design, refer to one of the many books available on the topic. There are also a lot of tutorials on the Internet which you can take as a starting point.
The Unified Modelling Language (UML) is a diagramming language or notation to specify, visualize and document models of Object Oriented software systems. UML is not a development method, that means it does not tell you what to do first and what to do next or how to design your system, but it helps you to visualize your design and communicate with others. UML is controlled by the Object Management Group (OMG) and is the industry standard for graphically describing software.
UML is designed for Object Oriented software design and has limited use for other programming paradigms.
UML is composed of many model elements that represent the different parts of a software system. The UML elements are used to create diagrams, which represent a certain part, or a point of view of the system. The following types of diagrams are supported by Umbrello UML Modeller:

• Use Case Diagrams show actors (people or other users of the system), use cases (the scenarios when they use the system), and their relationships
• Class Diagrams show classes and the relationships between them
• Sequence Diagrams show objects and a sequence of method calls they make to other objects.
• Collaboration Diagrams show objects and their relationship, putting emphasis on the objects that participate in the message exchange
• State Diagrams show states, state changes and events in an object or a part of the system
• Activity Diagrams show activities and the changes from one activity to another with the events occurring in some part of the system
• Component Diagrams show the high level programming components (such as KParts or Java Beans).
• Deployment Diagrams show the instances of the components and their relationships.
• Entity Relationship Diagrams show data and the relationships and constraints between the data.