Critical Path and Scheduling Using Priority Lists

This applet allows the user to create and edit all the inputs in a scheduling project (tasks, precedence relations, processing times). The user can also choose the number of processors and input a priority list. The applet will create the project digraph, show the critical path for the project and create a schedule for the project.

Instructions

  • The Project Table Tab

    Start by clicking on the Project table tab. Each row on the table represents a task. You can add or remove tasks by clicking on the Add task or Remove task button.

    For each task, you can input (and edit) the task name (it is recommended that you use single letter names), the processing time (in the Task duration column), and the list of tasks that immediately precede the task (in the Comes after column enter the task names separated by commas). If the Comes after field is left empty, the applet will automatically assume that the task follows Start. To input data, first click on the cell (its background turns white), then enter the data.

    When finished entering the data, click on the Apply button to update and store the information you entered. To start a new scheduling project, click on the New project button.

  • The Project Graph Tab

    After entering the project information on the Project table, clicking on the Project graph tab shows a digraph for the project. The applet is programmed to display a reasonable looking digraph, but this is not always possible. You can improve the looks of the digraph by changing the placement of the tasks (first click on the Drag nodes button and then click and drag the tasks to better positions). This change does not affect the digraph, only the way it looks!

    If you click on the Compute Critical Path button, the applet will display the critical path for the project in red.

  • The Project Schedule Tab

    Clicking on the Project Schedule tab will show the project digraph and a blank timeline for a schedule. (If the Compute critical path was selected, the timeline will display the schedule produced by the critical path algorithm). In this tab you can

    1. change the number of processors assigned to the project (click on the # of processors to edit the number- clicking a little right of center increases the number; clicking left of center decreases the number), and

    2. enter a priority list (enter the names of the tasks in order, separated by commas).

    After you have entered the tasks, processing times, and precedence relations; chosen the number of processors and entered the priority list for the tasks, click on the Schedule button. The timeline will show the schedule for the project.

    After the schedule is completed the state of the tasks at any particular instance can be observed by clicking anywhere in the timeline area.


This applet requires Sun's Java VM 2 which your browser may perceive as a popup. Which it is not. If you want to see the applet work, visit Sun's website at http://www.java.com/en/download/index.jsp, download and install Java VM and enjoy the applet.


What if applet does not run?

(A newer version of the applet is also available on the web.)


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