Detecting Duplicates Using Oracle Business Rules

Recently I was involved with a Business Process Management Proof of Concept (BPM PoC) where we wanted to show how customers could use Oracle Business Rules (OBR) to easily define some rules to detect certain conditions, such as duplicate account numbers, duplicate names, high transaction amounts, etc, in a set of transactions.

Traditionally you would have to loop through the transactions and compare each transaction with each other to find matching conditions. This is not particularly nice as it relies on more traditional approaches (coding) and is not the most efficient way.

OBR is a great place to house these types’ of rules as it allows users/developers to externalise the rules, in a simpler manner, externalising the rules from the message flows and allows users to change them when required. So I went ahead looking for some examples. After quite a bit of time spent Googling, I did not find much out in the blogosphere. In fact the best example was actually from...... wait for it...... Oracle Documentation! (http://docs.oracle.com/cd/E28271_01/user.1111/e10228/rules_start.htm#ASRUG228)

However, if you followed the link there was not much explanation provided with the example. So the aim of this article is to provide a little more explanation to the example so that it can be better understood.

Note: I won’t be covering the BPM parts in great detail.

Use case:

Payment instruction file is required to be processed. Before instruction file can be processed it needs to be approved by a business user. Before the approval process, it would be useful to run the payment instruction file through OBR to look for transactions of interest. The output of the OBR can then be used to flag the transactions for the approvers to investigate.

BPM Process

Example BPM Process


So let’s start defining the Business Rules Dictionary. For the input into our rules, we will be passing in an array of payments which contain some basic information for our demo purposes.

Input XSD

Input to Business Rules

And for our output we want to have an array of rule output messages. Note that the element I am using for the output is only for one rule message element and not an array. We will configure the Business Rules component later to return an array instead.

Output from Business Rules

Dictionary

Business Rule – Create Dictionary

Fill in all the details and click OK. Open the Business Rules component and select Decision Functions from the side.

Modify the Decision Function Configuration

Select the decision function and click on the edit button (the pencil), don’t worry that JDeveloper indicates that there is an error with the decision function. Then click the Ouputs tab and make sure the checkbox under the List column is checked, this is to tell the Business Rules component that it should return an array of rule message elements.

Updating the Decision Service

Next we will define the actual rules. Click on Ruleset1 on the side and then the Create Rule in the IF/THEN Rule section.

Creating new rule in ruleset

Ok, this is where some detailed explanation is required. Remember that the input to this Business Rules dictionary is a list of payments, each of those payments were of the complex type PaymentType. Each of those payments in the Oracle Business Rules engine is treated as a fact in its working memory.

Implemented rule

So in the IF/THEN rule, the first task is to grab two PaymentType facts from the working memory and assign them to temporary variable names (payment1 and payment2 in our example).

Matching facts

Once we have them in the temporary variables, we can then start comparing them to each other. For our demonstration we want to find payments where the account numbers were the same but the account name was different.

Suspicious payment instruction

And to stop the rule from comparing the same facts to each other, over and over again, we have to include the last test.

Stop rule from comparing endlessly

And that’s it! No for loops, no need to keep track of what you have or have not compared, OBR handles all that for you because everything is done in its working memory. And once all the tests have been satisfied we need to assert a new fact for the output.

Assert the output fact

Save your Business Rules. Next step is to complete the data association in the BPM process. Pay extra care to use Copy List instead of the default Copy when doing data association at an array level.

Input and output data association

Deploy and test.

Test data

Rule matched

Parting words:

Ideally you would then use the output of the Business Rules component to then display/flag the transactions which triggered the rule so that the approver can investigate.

Link: SOA Project Archive [Download]

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