Analyzing Activities › Dependency Analysis › Some Additional Dependency Concepts

Some Additional Dependency Concepts

These are less obvious situations that arise in dependency analysis:

• A single process can be a prerequisite to several dependencies, which is based on different post-conditions.
• In this case, separate dependency lines are drawn. Consider the following illustration.

  

• Assume that Schedule Class in the illustration satisfy two post-conditions.
• Assume that Order Class Materials has the condition "class requirements are identified" as its precondition.
• Assume that Accept Class Reservation has the precondition "class roster opened." This condition is associated with a repetitive dependency, because Accept Class Reservation execute many times as a result of this condition.
• When multiple conditions are not mutually exclusive, multiple enabling dependencies appear in the diagram.
• If the dependent process in a dependency is a repetitive process, the dependency is named a repetitive dependency. This means that when the prerequisite process executes, its post-condition can satisfy the precondition of multiple executions of the dependent process. An example of this is in the following illustration.

  

• A single execution of Schedule Delivery satisfies the post-condition "product stock not available."
• Multiple executions of Schedule Production (one for each production period) can be executed based on the precondition of Schedule Production "product stock not available."
• There is mutually dependent processes, where each process depends the other process.
• The following illustration expands on the example in the previous illustration to show this situation.

  

• Assume that Schedule Delivery can result in a condition "product stock not available," which is a precondition of Schedule Production. If enough product stock is available when scheduling the order, it is possible to reserve product stock. If there is not, Schedule Production must be executed repeatedly until enough product is scheduled. When production is scheduled, it is possible to try to schedule the delivery again. In one situation, then, Schedule Production depends Schedule Delivery, while in another, Schedule Delivery depends Schedule Production.
• It is possible to specify a sequential dependency in which a process is dependent upon itself. Such a dependency is named a recursive dependency.
• This indicates that one execution of the process satisfies a post-condition that is a precondition of a subsequent execution of the process. This typically occurs when the process interacts with an entity type that has an involuted relationship, or whose entities are otherwise associated indirectly with other entities of the same entity type.
• Refer to the following illustration.

  

• Assume that Decompose Bill of Materials is a process that decomposes one level of a bill of material structure. Bill of material structures are discussed in the chapter "Building the Analysis Model." To decompose the entire bill of materials, Decompose Bill of Materials must execute one or more times for each level of t he structure.