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Project Scheduling Tools As part of CSA3040 © 2003, 2004 – Dr. Ernest Cachia

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 2 Project Schedule Components Activities Resources (including the human type) Time (durations and deadlines) Products Sequence Checks

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 3 The Problem Scheduling requires strict planning and a fair amount of prognosis There are many factors that determine a schedule (see previous slide) Getting all the aspects of a schedule rightly concerted is a very difficult task – even for relatively small projects Scheduling is of paramount importance in project management Therein lies the problem!

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 4 A Solution Techniques and supporting tools

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 5 Activity Network Diagrams Practically the same A more modern variation of PERT and CPM Available in two flavours Activity-On-Arrow (AOA) Activity-On-Node (AON) Diagram type names PERT (Program Evaluation Review Technique) CPM (Critical Path Method) PN (Precedence Network) AOA: PERT and CPM AON: Precedence Networks Not part of the NCC BCIS syllabus

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 6 AOA Diagrams Diagram components (symbols) Nodes (drawn as circles) Links (drawn as directed arcs) Symbol meanings Nodes: Start/Stop events (points) Links: Activities

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 7 AOA Diagrams Construction Rules Must contain only one start and one end node A link has duration (optionally shown) A node has no duration (simply start/stop point) Time flows from left to right Nodes are numbered sequentially Loops are not allowed (by concept) Dangles are not allowed (except in the case of the one and only end node)

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 8 AOA Diagram Example (1/2) 123 4 56 A B C D F E G H Explanation: The above project (or part of) consists of eight activities (“A”~“H”). The duration of each activity is not indicated. The project starts at node one and ends at node six. The derived duration of activity “A” is the time difference between node two and node one; the derived duration of activity “B” is the time difference between node four and node 1; and so on.

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 9 AOA Diagram Example (2/2) 1 3 2 4 5 Read sources Start word processor Type personal notes Write some rev. questions... Explanation: There are four activities in all. A student reads from various sources and starts a word-processor to then type in some personal notes and furthermore, manually writes some questions on paper to remember to ask the lecturer. IN PRACTICE reading and writing questions can proceed separately from starting the word processor to type in some personal notes. THEREFORE…

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 10 Separating Activity Paths (from example on previous slide) 1 3 2 4 5 Read sources Start word processor Type personal notes Write some rev. questions... 3a Dummy link Please note, that a dummy link has zero duration time and uses absolutely no resources.

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 11 Lagged Parallel Activities To show the delayed start/finish of parallel activity sequences. 13 2 Get client feedback on first prototype Develop second prototype 5 3 days1 day...

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 12 Labelling Activities (PERT Style) One way: A simpler way: ID Earliest date Latest date Slack Earliest date Latest date

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 13 Scheduling Analysis (using PERT) Example (taken from Hughes) Initial activity network: 1 ? ?? 2 ? ?? 3 ? ?? 4 ? ?? 6 ? ?? 5 ? ?? A B C D E F G H ActivityDuration (weeks)Precedents A: H/W selection6 B: S/W design4 C: Install H/W3A D: Code/Test S/W4B E: Data input3B F: User manuals10 G: User training3E,F H: Install/Test sys.2C,D Project schedule specification table:

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 14 Rule: The earliest date for an event is the earliest finish date for all activities ending at that event. Where common ending activities are present, the latest of the earliest finish dates is taken. Start date for A, B, F = 0. If duration of A = 6 weeks (see project schedule specification table), then earliest date for event 2 is 6 weeks. If duration of B = 4, then earliest date for event 3 is 4 weeks. And so on, simply adding on the weeks from one event to the next on every path through the network This will produce the diagram on the next slide… Analysis: The “Forward Pass”

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 15 Resulting from the “Forward Pass” 1 ? ?0 2 ? ?6 3 ? ?4 4 ? ?9 6 ? ?13 5 ? ?10 A=6 B=4 C=3 D=4 E=3 F=10 G=3 H=2 This is the resulting diagram from a “forward pass”:

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 16 The “Backward Pass” Rule: The latest date for an event is the latest start date for all activities commencing from that event. Where common commencement from an even is present, the earliest of the latest start dates is taken. Latest finish date for H, G = their earliest finish date = 13. If duration of H = 2 weeks, then latest date for event 4 is latest date for event 6 – duration of H (i.e. 13-2) = 11. While the latest date for event 5 is latest for 6 – duration of G (i.e. 13-3) = 10. The latest for event 3 is the latest of (11-4) and (10-3), both giving the value 7. And so on, simply subtracting the duration of an activity from the latest date of the event it terminates at, for every path through the network (hence “backward pass”)

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 17 Resulting from the “Backward Pass” 1 ? 00 2 ? 86 3 ? 74 4 ? 119 6 ? 13 5 ? 10 A=6 B=4 C=3 D=4 E=3 F=10 G=3 H=2 This is the resulting diagram from a “backward pass”:

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 18 Calculating “Slack” (aka “Float”) Rule: “Slack” is the difference between the earliest and the latest start/finish dates of an event. This is the resulting diagram with “slack” included: 1 0 00 2 2 86 3 3 74 4 2 119 6 0 13 5 0 10 A=6 B=4 C=3 D=4 E=3 F=10 G=3 H=2

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 19 The “Critical Path” This is the longest time to project termination. The path through the PERT chart (activity network) that has no slack. Therefore… 1 0 00 2 2 86 3 3 74 4 2 119 6 0 13 5 0 10 A=6 B=4 C=3 D=4 E=3 F=10 G=3 H=2

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 20 AON Diagrams Diagram components (symbols) Nodes (drawn as circles or squares) Links (drawn as directed arcs) Symbol meanings Nodes: Activities with specific durations Links: Precedence (sequencing) These diagrams are not included in your (BCIS) syllabus. Feel free to research them individually for better background.

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 21 Project Planning Diagrams You should have already discussed this type of chart in earlier courses, so I will be very brief. Bar charts (aka Gantt charts) can be put to multiple uses. However in s/w development they are mainly used for… Staff allocation Who does what Activity schedule When activities begin and end (activity extent)

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 22 Gantt Chart Example 1 0 00 2 2 86 3 3 74 4 2 119 6 0 13 5 0 10 A=6 B=4 C=3 D=4 E=3 F=10 G=3 H=2 Time (weeks) A B C D E F G H Activity 103 2 54768109121113 Based on this PERT chart: Critical path

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Sep. 2003(C) 2003 - Dr. Ernest CachiaSlide 23 That’s it! No more personal slides on scheduling tools

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