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Chapter 2 ASE

Chapter 2 ASE






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    Chapter 2 ASE Chapter 2 ASE Presentation Transcript

    • Planning and Scheduling: 1
    • • Allocation of resources to activities over time so that input demands are met in a timely and cost-effective manner• Most typically, this involves determining a set of activity start and end times, together with resource assignments, which – satisfy all temporal constraints on activity execution (following from process considerations) – satisfy resource capacity constraints, and – optimize some set of performance objectives to the extent possible 4
    • Planning and Scheduling:Gantt Chart• A Gantt chart is a type of bar chart, developed by Henry Gantt, that illustrates a project schedule. Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project. Terminal elements and summary elements comprise the work breakdown structure of the project. Some Gantt charts also show the dependency (i.e., precedence network) 5
    • • Use a Gantt chart to plan how long a project should take. A Gantt chart lays out the order in which the tasks need to be carried out. Early Gantt charts did not show dependencies between tasks but modern Gantt chart software provides this capability. Henry Laurence Gantt, an American mechanical engineer, is credited with the invention of the Gantt chart. 6
    • • Gantt charts have become a common technique for representing the phases and activities of a project work breakdown structure.• A work breakdown structure (WBS) is a deliverable oriented decomposition of a project into smaller components.• A work breakdown structure element may be a product, data, a service, or any combination. 7
    • • Gantt charts only represent part of the triple constraints of projects.• Gantt charts do not represent the size of a project or the relative size of work elements.• Magnitude of a behind-schedule condition is easily mis communicated. 8
    • Planning and Scheduling: Gantt Chart• List tasks• Graphically represent dependencies among tasks• Show duration and time period of each task• Heavily dependent on prediction regarding: – Activities involved – Effort and time required 9
    • Gantt chart example • Programmer working on a small software project Explicit start time, end time, and duration (in days ) Dec 2002 Du ratioID Task Name Start Fi nish n 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 311 Requireme nt gathering 12 /5/2002 12/6 /2002 2d2 Analysis 12 /9/2002 12/9 /2002 1d3 Design 12/10/2002 12/11/2002 2d4 Coding 12/12/2002 12/17/2002 4d5 Testing 12/18/2002 12/31/2002 10d Explicit calendar bar 10
    • Another Gantt 11
    • Planning and Scheduling: Pert chart Duration Start time 12/5/2002 2 12/6/2002 Requirement gathering Late Start Slack Late Finish End time Task 12/9/2002 1 12/9/2002 Analysis• Alternative to Gantt chart Late Start Slack Late Finish• Different perspective 12/10/2002 2 12/11/2002 Design – Focuses on dependencies Late Start Slack Late Finish more than calendar time 12/12/2002 4 12/17/02 Coding• No fixed format Late Start Slack Late Finish 12/18/2002 10 12/31/2002 Testing Late Start Slack Late Finish 12
    • Another Pert 13
    • So how do you know how long a task is going to take? 14
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    • Function Points• A.J. Albrecht of IBM, ~1979.• FP is a unit for estimating time and effort independent of programming language.• Identify set of application activities (building blocks) and sum the weights assigned to each.• From user’s viewpoint. 23
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    • Determine the Unadjusted Function Point Count• The unadjusted function point count (UFPC) reflects the specific countable functionality provided to the user by the project or application.• The applications specific user functionality is evaluated in terms of what is delivered by the application, not how it is delivered. Only user- requested and defined components are counted.• The unadjusted function point count has two function types—data and transactional. 27
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    • Count Data Functions1. An internal logical file (ILF) is a user identifiable group of logically related data or control information maintained within the boundary of the application. The primary intent of an ILF is to hold data maintained through one or more elementary processes of the application being counted.• Tables in a relational database.• Application control information, perhaps things like user preferences that are stored by the application. 29
    • 2. An external interface file (EIF) is a user identifiable group of logically related data or control information referenced by the application, but maintained within the boundary of another application. This means an EIF counted for an application must be in an ILF in another application. 30
    • Count Transactional Functions• An external input (EI) is an elementary process that processes data or control information that comes from outside the application’s boundary.• The primary intent of an EI is to maintain one or more ILFs and/or to alter the behavior of the system. 31
    • • An external output (EO) is an elementary process that sends data or control information outside the application’s boundary. The primary intent of an external output is to present information to a user through processing logic 32
    • • An external inquiry (EQ) is an elementary process that sends data or control information outside the application boundary. The primary intent of an external inquiry is to present information to a user through the retrieval of data or control information. The processing logic contains no mathematical formula or calculation, and creates no derived data. No ILF is maintained during the processing, nor is the behavior of the system altered. 33
    • Low Medium HighInput files 3 4 6Output files 4 5 7Inquiries 3 4 6Internal files 7 10 15External 5 7 10interfaces 34
    • Determine the Value Adjustment FactorThe value adjustment factor (VAF) indicates the generalfunctionality provided to the user of the application. TheVAF is comprised of 14 general system characteristics(GSCs) that assess the general functionality of theapplication. Each characteristic has associateddescriptions that help determine the degree of influenceof the characteristic. The degrees of influence range ona scale of zero to five, from no influence to stronginfluence 35
    • Value Adjustment Factor 1. System Complexity 2. I/O Complexity 3. Application Complexity1.1 Data 2.1 Reliable and 3.1 Algorithms andcommunication transaction-oriented processing ability data management1.2 Distributed data 2.2 Online data 3.2 Need to reuse theprocessing management code later1.3 Relevance of 2.3 Usability and 3.3 Installation easinessperformance efficiency of end user1.4 Configuration of 2.4 Online update of 3.4 Startup, shutdown,hardware and software the data and operation easiness Partial (1) Partial (2) 3.5 Requirements to run on multiple sites 3.6 Readiness to change Partial (3) Total 36
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    • Function Points• 14 “technical factors” related to complexity – Grouped under 3 classes of complexity: system, I/O, application – Each factor ranked from 0 to 5• Technical complexity factor (TCF) (∑ ) The sum of the 14 factors’ ranks 14 TCF = i=1 TCFi × 0.01• Adjusted function points (AFP or FP) FP = UFP * (0.65 + TCF) 38
    • Determine Type of Count Development Project• Functions provided to the users with the first installation. Enhancement Project• Measures the modifications to the existing application that add, change, or delete user functions delivered.• Application function point count must be updated to reflect changes in the applications functionality. 39
    • Application Project• Referred to as the baseline or installed function point count. This number is initialized when the development project function point count is completed. It is updated every time completion of an enhancement project alters the applications. 40
    • UFP for Making Cappuccino Name Type Complexity Value (building block)Milk Input File Medium 4Coffee Input File Medium 4Water Input File Low 3Cappuccino Output File High 7Water Temperature Inquiry Low 3External Temperature External Interface Medium 7 Total Unadjusted Function Points 28 41
    • FP for Making Cappuccino 1. System Complexity 2. I/O Complexity 3. Application Complexity1.1 Data communication 5 2.1 Reliable and 0 3.1 Algorithms and 1 transaction-oriented data processing ability management1.2 Distributed data 3 2.2 Online data 4 3.2 Need to reuse the code 0processing management later1.3 Relevance of 4 2.3 Usability and 4 3.3 Installation easiness 5performance efficiency of end user1.4 Configuration of the 4 2.4 Online update of the 2 3.4 Startup, shutdown, and 3hardware and the software data operation easiness Partial (1) 16 Partial (2) 10 3.5 Requirements to run 2 on multiple sites 3.6 Readiness to change 2 Partial (3) 13 Total = 39 42
    • FP for Making Cappuccino• FP = UFP * (0.65 + TCF) = 28 * (0.65 + (39 * 0.01)) = 29.12• So what was the time/effort required last time your firm implement 29 FPs? 43