simplify your processes with decision modeling
TRANSCRIPT
Simplify Your Processes with Decision Modeling
Tom Debevoise
Chief Evangelist Business Decision Management, Signavio, Inc. Whitepaper January 2016
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Table of Contents
1. Introduction 3
2. Business Rules in BPMN - Step 1 3
3. Adding Business Rules - Step 2 5
4. Benefits of DMN 6
5. Contact 7
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1. Introduction
Business Process Model and Notation (BPMN) is the defacto standard for process modeling. However, BPMN is not truly meant to create business rules, statements that dictate what decisions should be made given a certain set of conditions. The new OMG standard Decision Model and Notation (DMN) 1.0 fills this gap in process modeling. DMN was designed as a graphical notation that models decisions and connects them to their related processes. With DMN, organizations finally have a standardized way to model and manage decisions and their business rules logic.
Decision modeling simplifies processes through the splitting of gateways and scripts into sepa- rate diagrams, thereby reducing the number of shapes and edges (lines). Decisions actually direct the flow of activities, allowing processes to respond dynamically to new business rules without the processes themselves changing. Process and decision diagrams have indepen- dent life cycles. Most business changes actually originate from the decision/rule level, so much can be achieved by focusing effort there.
Business rules are always evolving as a result of updates to best practices, regulatory changes, etc. This reality is reflected through decision modeling, allowing organizations to make consistent decisions and carry out end-to-end processes in the face of constant change.
2. Business Rules in BPMN - Step 1
The figure below presents a process fragment in BPMN with embedded business rules. The fragment defines how to determine a customer loyalty discount. The first activity computes the customer’s total purchases. Next, a gateway (the input data of the business rules) points to a loyalty discount, the activity that assigns the discount. Within each activity that assigns a discount is probably a script that assigns a discount value to a variable. Each branch of the gateway repre- sents the “outcome” of a business rule. For instance the top branch can be read: IF purchases > $10K then Discount = 6%. So in BPMN a business rule has at least three parts, the gateway, the sequence, and an activity (which may be comprised of multiple “task” elements.)
Figure 1: A BPM process model with simple business rules.
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The process in Figure 1 can be represented as the following decision diagram in DMN:
Figure 2: A decision diagram representing the rules in the process in Figure 1.
The logic of the business rules are described in a decision table attached to the decision. The deci- sion table for the rules is shown in Figure 3.
Figure 3: A decision table for the rules in Figure 1.
With this approach, the BPM process is now simplified with a rules shape Task type, as shown in Figure 4.
Figure 4: The discount process with a rule activity that invokes the decision in Figure 2.
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3. Adding Business Rules - Step 2
Now suppose a business decision is made to add another discount policy to the process: offer additional discounts for loyal customers who have made purchases over a period between two and five years. If we add this logic to the process diagram from Figure 1 without using DMN, we now see the added complexity required to describe this additional policy in Figure 5:
Figure 5: The discount decision with rules related to years of loyalty.
Now the rules read: IF purchases > $10K AND loyalty years > 5 THEN Discount = %5.
The logic adds additional gateways that must be checked after the total purchases are checked. It’s easy to see how additional discounting factors such as purchase guarantees would make this process diagram pretty unwieldy to manage and difficult to interpret. A process modeler might even be tempted to create sub-processes to model the discount logic. The approach of breaking decisions like this into numerous diagrams can make understanding and end-to-end process nearly impossible.
In Figure 6, the decision diagram in DMN is shown.
Figure 6. The decision diagram for computing a discount with the additional input of loyalty years.
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The decision table for the rules in Figure 5 is shown in Figure 7.
Figure 7: The business rules for Figure 5.
Clearly, it is much simpler to add rules to decision tables than to add gateways, sequences and activity (task) elements to process diagrams. Arguably the decision logic is easier to read and understand. In addition, if BPMN is used by itself, the code or scripts that calculates the discount must be added and maintained in multiple tasks. In our example, we used DMN to define the discount rules and determine a new discount, leaving the process shown in Figure 4 unchanged.
4. Benefits of DMN
DMN can be used to separate process logic and decision logic. As a result, management and mainte- nance of both are simplified. In many cases, the business rules will change more frequently than the process, causing significant problems when processes are “in-flight”. If a sub-process with busi- ness rules that need changing is in-flight, then it is difficult to change the rules in that process. Because DMN is de-coupled from the process, it is easier to deploy a new version of the decision.
Additionally, if you have created an executable version of your process model, there is no need to redo the technical implementation of the BPM process. The new rules are simply interpreted by the rules engine before the results are passed to the process. By eliminating the need to update process models, DMN creates large IT cost savings. Even when process models stay the same, and the only change is to decision logic, DMN drastically increases agility.
DMN can also be used to customize processes for “localized” practices. With one process it is possible to have independent rules supporting variants. Take for example, a company that provides an outsourcing service for the student application process to multiple universities. The process is the same for all universities, but the decision logic is completely different for each university and curriculum. While the process logic is defined centrally by the outsourcing provider, the decision logic can be defined and maintained in a decentralized manner by each university.
With the new DMN standard, organizations are now reaping all these benefits and unleashing the full potential of their processes.
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5. Contact
EMEA
Signavio GmbH
Nürnberger Straße 8
10787 Berlin
Germany
The Americas
Signavio, Inc.
440 N. Wolfe Rd.
Sunnyvale, CA 94085
USA
APAC
Signavio Pte. Ltd.
100 Cecil Street
#10-01/02 The Globe
Singapore 069532
+49 30 856 21 54-0
+49 30 856 21 54-19
+1 650 388 9251
+1 650 388 9252
www.signavio.com
Singapore: +65 6631 8334
Australia: +61 3 9008 4272