Analyzing Activities › Process Decomposition › Identifying Elementary Processes

Identifying Elementary Processes

An elementary process is a process that is the smallest unit of business activity of meaning to the business and that, when complete, leaves the business in a consistent state.

The main challenge during process decomposition lies in taking a business perspective on activities that are typically described by users in terms of their current procedures. This perspective is drawn from the business purpose or value to first model the processes that are currently performed and then all the activities that serve the purpose. This identifies a comprehensive set of elementary processes to be performed.

This ideal or improved set of processes are simpler than what is performed. For example, current procedures are grouped into processes that are performed at a single time, as soon as an order is received, or when an order is due to be delivered.

Activities that add value is performed as soon as possible, activities that incur cost, or that do not add value is performed as late as possible ("just in time"), or even omitted altogether.

The project objectives may involve continuous process improvement or radical business process re-engineering. These objectives guide analysts and business managers in the extent of the change that is desirable from the current procedures and processes.

As expected, a process that is described as elementary cannot be further decomposed, at least not into subordinate processes using the Activity Hierarchy Diagram. So, each elementary process is a leaf in the hierarchy. When the activity hierarchy is complete, all leaves are elementary processes.

Identify elementary processes properly because they form the basis for an implementation as parts of a business system.

These guidelines are applied to test each process that is suspected of being elementary to ensure that it falls above or below the elementary process level.

• Each execution of the process must produce a result that, to the business, is complete and meaningful.
• Another way of saying this is that each execution must make all necessary changes to business data, and must leave all data in a consistent state, conforming to all data integrity rules.
• A process that violates this rule is below the elementary process level, indicating that decomposition has progressed to too low a level. Such a process is part of a higher-level activity that is an elementary process.
• The process operates on a set of data in common with its sibling processes to which it is closely related.
• The concept that is used to measure this degree of relatedness is named cohesion and is further described in the chapter "Building the Analysis Model."
• Each process must be included in the response of at least one event.
• It either itself be the first process that is directly enabled by the event, or it is indirectly connected to that first process through dependencies.
• None of the elements of process can be executed individually to leave the business data in a consistent state.
• This rule can be applied whenever event analysis has been performed. See the chapter "Event Analysis" for more information.
• A process that violates this rule is above the elementary process level, indicating that the process has elementary processes among its children.

A test for a complete result would check to see that all data actions that must be performed together are performed together. For example, creating an order must include creating at least one order item.

A test for a meaningful result is to ask if the business recognize whether a process has taken place for the entities affected. For example, it is of interest to know that an order has been canceled, but whether the business wants to know that it has been amended need further investigation.

For example, the following illustration shows an Activity Hierarchy Diagram in which all the subordinate activities are processes.

Assume that the fragment of the Entity Relationship Diagram in the following illustration has already been described in the business model.

Assume also that the following descriptions of the business are true:

• When a customer places an order, all the header information for the order is recorded, after which an Order Item is established for each different type of product ordered.
• When an order is corrected, or amended, a correction is typically made either to the header (for example, the customer changes the requested date of shipment) or to a single-line item (for example, the customer request a change to the quantity of product ordered) but not to both.

Is Record Order Header an Elementary Process?

Record Order Header is a process that captures the details of an order entity but none of its order items. Applying the guidelines in this section results in the following observations:

• An execution of Record Order Header by itself does not leave business data in a consistent state. An order cannot exist without order items. The relationship is fully mandatory.
• An execution of Record Order Header without an execution of Record Order Item is unlikely to produce a complete and meaningful result. More likely, the creation of an entire order and all its order items constitutes a result meaningful to the individual taking the order.
• Record Order Header has no elements that are individually executable. It is imaginable that a decomposition of Record Order Header would result in subordinates such as Identify Customer, Check Customer Credit, and Record Date Requested, but it is difficult to imagine the execution of those elements independently of one another.

Because it fails to satisfy the first two guidelines, Record Order Header is clearly not an elementary process; neither is Record Order Item. Since the first two guidelines are violated, the process is sub-elementary. An elementary process higher in the hierarchy is identified.

Now consider the process Customer Ordering. Applying the guidelines for identifying elementary processes yields the following results:

• Each execution of Customer Ordering in this example leaves business data in a consistent state.
• Each execution of Customer Ordering is likely to produce a newly taken order, an order cancellation notice, or an amended order, each of which are complete and meaningful to the user.
• The elements of Customer Ordering can be executed individually. For example, it is sensible to take an order without canceling one in the same execution.

Customer Ordering fails to comply with the last guideline, and so is above the level of being an elementary process. Also, Record Order Header is at too low a level. So Take Order is likely to be an elementary process.

Applying the guidelines to Take Order reveals:

• Each execution of Take Order leaves the data in a consistent state, because both an order and its order items are accepted during the same execution.
• Each execution of Take Order produces a result (that is, an order) that is complete and meaningful to the user in itself.
• Neither element of Take Order (Record Order Header and Record Order Item) can be executed independently of one another, as explained previously.

Since Take Order complies with every guideline, it is an elementary process.

Consider the Amend Order process. It decomposes in a similar way to Take Order, which was found to be an elementary process. However, based on the underlying set of assumptions, Amend Order Header and Amend Order Item can be executed independently of one another. Given that Amend Order Header and Amend Order Item each produce an amended version of the order, they are elementary processes, each produces meaningful results and leaves the business in a consistent state, even though Record Order Header and Record Order Item were not. This example illustrates that even when decomposition is similar, the designation of elementary processes are different.

The results of this analysis are shown in the following illustration.

The corrected activity hierarchy diagram in the illustration shows that the decomposition of Customer Ordering terminates at the elementary processes Take Order, Cancel Order, Amend Order Header, and Amend Order Item.

Since process decomposition stops at the elementary process level, the sub-elementary processes, Record Order Header, and Record Order Item, have been removed.