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University of California, Davis

Application Development Methodology

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Concepts

Condition

A rule expressed in terms of predicates or constants that describes an aspect of the business that causes the business to decide to do some activity or to stop some activity.

Process conditions test the states of the business at the time of execution and change the business process depending on the results of the test.

Procedure conditions test the states of the attributes or fields or the actions of the operator at the time of execution and change the computer procedure depending on the result.

Condition Logic

The condition logic is an expression of a predicate condition that may be expressed in the form "If P then Q".

Conditional Statement

A unit of activity in an action diagram wherein a condition is expressed that controls a subsequent process, procedure or step execution.

Selection Condition

A rule expressed in terms of predicates and constants, used to select one or more entities of a given type for involvement during the execution of a process or a procedure step.

Selection conditions are used to describe which entity occurrences are to be acted on during an execution of a process or procedure. They consist of the criteria that are needed to select the required entities unambiguously.

Selection can occur by two methods:

* Selection by the existence of a grouping under a named relationship

* Selection by the range of values of a named attribute

That is, entities can be selected because they participate in a given relationship membership, and entities can be selected because some or all of their attribute values meet given criteria.

It is possible to combine both methods in a single selection condition. It is also possible to act on all entities of an entity type.

Conditional Membership

The membership of an entity in a pairing where that membership depends upon some predicate values.

Example of Selection Conditions

READ existing customer WITH name = "Smith"

READ account WHICH is owned by existing customer

Execution Condition

A rule expressed in terms of predicates or constants that states when an activity (process or action group) may or may not be executed.

Execution conditions are used to determine the combination of actions that will enable each execution of a process or procedure. Not all actions occur every time a process or procedure occurs; execution conditions specify the circumstances in which an action does occur.

Example of Execution Conditions

IF existing customer status IS EQUAL TO "priority" USE priority dispatch

Execution Preconditions and Post-conditions

Optionality, cardinality and exclusivity can all be affected by conditions that detail constraints on the execution of a process (i.e., preconditions) or on the possible outcomes of execution. Optionality conditions specify when a dependency may enable execution of a process, but its absence may not prevent execution.

Conditional Subprocess

A process whose execution depends on predicate values established by prior processes.

What Conditions Are and Are Not

Conditions are expressed in terms of entity states or time events. These conditions constrain the execution of the process and are defined for the process, but they are not part of the logic of the business process. They are part of the control logic, and can be documented within the process description. To define the conditions accurately, you must have analyzed the entity type life cycles and have been through some iteration between dependency and life cycle analysis.

Cardinality Conditions

Cardinality conditions determine the number of executions of a dependent process or the number of times a preceding process may execute for each execution of a dependent process.

Exclusivity Conditions

Exclusivity conditions determine which one of a number of possible alternative dependencies may either enable a process or be established by a process.

Compound Conditions

Simple conditions can be combined into a single, compound condition that defines all constraints upon executions or outcomes of a process. The constraints may be the presence or absence of dependencies associated with the process. They can be combined using logical operations. For example, the precondition of PAY SUPPLIER could be WHEN month ends AND received supplier invoice OR part-paid supplier invoice AND IF scheduled payment

Preconditions and Results

The set of conditions that constrain the execution of a process is known as its precondition; the set that constrains the outcome is known as its result.