woensdag 10 mei 2017

Oracle Process Cloud Service - Decision Model Notation part 2


In my previous blog, I showed how to get started with Decision Model Notation (DMN) in Oracle Process Cloud Service and how to create a simple Decision Table. Picking up from there, we will now look into creating If-Then-Else rules, which should also be familiar to people who know Oracle's old Business Rules. We will also create a service and call it from a process.

Creating an If Then Else Decision

As Input, I have created a TotalAmount object, which is the total amount of a Sales Order. Based on this TotalAmount, we are going to calculate a Discount Price, for which I have created a DiscountPrice type to make the service interface a bit prettier than just 'output'. To create an If-Then-Else rule, just click the + button next to Decisions, enter a name and set the output type to string, number or any other type, in this case DiscountPrice.


Now, Oracle will have created a rule for you, in which you only need to fill in the "if", "then" and "else". Since you've already decided your output object, we will not use that one in the expression, which is different from the old Oracle Business Rules. So just enter the value that you want for this object and you'll be fine. You can also create nested expressions, as shown below:

One thing that I don't like, is that all the nesting needs to be done in the "else" part. I hope for Oracle to acknowledge this and create a new "if" section (for example with indent), where I can happily nest away in a more user-friendly manner. However, it works (use the Test feature to verify) and if you don't make things too complicated, it's mainly a minor display issue.

Calling an If Then Else Decision

Calling any Decision from a process is super easy. Just make sure to have a service created for your Decision and deploy it, so the process can find it. In Oracle Process Cloud's Process Composer, you can then select "Decision" as a system task, select the Decision Model that you want to use and the service within that Decision Model that you want to call:


From here, you can make your data associations and you're done. Obviously, a process is generally not as simple as this one, but using Decisions within processes is.

So that's the second part of this blog series. The third part will be an overview of other DMN functionality: Expression, Relation, List, Function and Context. I still think that we will mostly be using If/Then/Else and Decision Tables though, so for most use cases, the information in this blog and the previous one should provide you with a nice kickstart.

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