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Software Project Management under Uncertainties
Event Chain Methodology: Event
Chains in Details
An event can activate other events immediately or with delay. Sometimes events can affect a future task. For instance, changes in requirements will lead to extra development in the future.
Sometimes, events can affect previous tasks in the project schedule. This is a common occurrence in software development, where an existing component requires refactoring to comply with a planned development. In this case, the refactoring task, which originally was not in the project schedule, will be automatically generated using the event “start task”. It leads to an important feature of the proposed methodology – the ability to reschedule activities using dynamically generated tasks.
Event chains can be modeled using circular relationships. Circular relationships are not just mathematical phenomena for the proposed methodology, they occur in the real world. For example, the development of a particular feature can fail because of a problem with software performance. To fix the performance problem, the developer must refactor an existing module. After this, the provability of failure of the performance test can be reduced. However, there is still a chance that the existing module must be refactored again. Project constraints such as deadlines and costs can be used to address the circular relationship problems.
In traditional methodologies, there are no relationships between tasks during the course of the task. In reality, synergies between tasks significantly affect project schedule. Event chains allow taking potential synergies into account. For example, if there is a delay in one task, other parallel tasks can be delayed. The scenario can be modeled by an event chain initiated by single event with an increased duration outcome.
In addition, event chains offer a possible solution to the resource allocation problem. This can be accomplished using the conditional events “Assign new resource” or “Reassign resource”, which are linked to the task deadline or an intermediate milestone. If there is a delay in a certain task caused by a specific event, new resources can be borrowed from another task and reassigned from the moment the event occurred. The task will then change its state and the project schedule will be recalculated with a new resource allocation. Simulation results will present the statistics of the resource allocations.
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