Consistency and tool abstraction: issues in the taskmaster environment

This thesis presents Taskmaster.2, a graphical environment for interactive task specification, execution and monitoring. Problem solving in the Taskmaster environment can be accomplished with top-down programming, bottom-up programming, or a mixture of the two. The use of top-down programming permits the user to start with a high level task and refine this task into successively lower level subtasks until, at the lowest level, each subtasks represents a software tool. Bottom-up programming is accomplished by beginning with the lowest level subtasks, software tools, and then combining these tools into successively higher level subtasks until, at the highest level, the high level subtask represents the original problem task. These programming methods provide the user with abstraction capabilities. Another abstraction capability within the Taskmaster.2 environment is the network tools. The user creates network tools by selecting several software tools that, combined, provide a certain functionality. These network tools can then be reused in solving other problem tasks. In fact, these tools appear no different to the user than the low level software tools: they are both single indivisible units. Providing complete abstraction capabilities, i.e., mixing programming styles (top-down and bottom-up) and network tools, maintains the consistency of the Taskmaster.2 environment. This makes the environment an easy one to learn, as well as remember.