DMN14 — DMN string join built-in function proposal

This is a proposal for a new DMN built-in function to join a list of strings, for which currently the specification does not offer any out-of-the-box support.

This is partially connected to OMG DMN RTF https://issues.omg.org/browse/DMN14-34, but it focuses only on a specific one, between of those functions.

Assessment

As of DMNv1.3 the specification is not offering any built-in support for the use-case of concatenating a list of strings into a final string.

Please notice this is not the use case of using the “+” operator as in:

first name + " " + last name

This is the use case of joining a list of strings, for example

[ "product 1", "product 2", ... ]

In the book “DMN Cookbook: 50 Decision Modeling Recipes to Accelerate Your Business Rules” by Bruce Silver and Edson Tirelli ISBN: 9780982368183, the authors are offering 3 working solutions in Chapter 4.2. This requires however the modeler to implement manually or in a “personal library” of BKMs the preferred solution.

The Signavio platform is offering it as a custom function (https://documentation.signavio.com/suite/en-us/Content/process-manager/userguide/dmn-literal-expressions.htm#concat) which however is only available on that specific platform.

It is likely other Vendors are offering this functionality in their own way.

This is an opportunity for the RTF to standardize what different people are doing differently, and not currently covered in the DMN spec.

Add String join function

This is a proposal for a new DMN built-in function to join a list of strings, for which currently the specification does not offer any out-of-the-box support.

This is partially connected to OMG DMN RTF https://issues.omg.org/browse/DMN14-34, but it focuses only on a specific one, between of those functions.

Assessment

As of DMNv1.3 the specification is not offering any built-in support for the use-case of concatenating a list of strings into a final string.

Please notice this is not the use case of using the “+” operator as in:

first name + " " + last name

This is the use case of joining a list of strings, for example

[ "product 1", "product 2", ... ]

In the book “DMN Cookbook: 50 Decision Modeling Recipes to Accelerate Your Business Rules” by Bruce Silver and Edson Tirelli ISBN: 9780982368183, the authors are offering 3 working solutions in Chapter 4.2. This requires however the modeler to implement manually or in a “personal library” of BKMs the preferred solution.

The Signavio platform is offering it as a custom function (https://documentation.signavio.com/suite/en-us/Content/process-manager/userguide/dmn-literal-expressions.htm#concat) which however is only available on that specific platform.

It is likely other Vendors are offering this functionality in their own way.

This is an opportunity for the RTF to standardize what different people are doing differently, and not currently covered in the DMN spec.