# Help needed with openEHR GDL

**URL:** <https://discourse.openehr.org/t/help-needed-with-openehr-gdl/1537>\
**Category:** Task Planning/GDL\
**Created:** [7 May 2021 15:55 UTC](https://discourse.openehr.org/t/help-needed-with-openehr-gdl/1537 "2021-05-07T15:55:40Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Rinke](https://discourse.openehr.org/letter_avatar_proxy/v4/letter/r/59ef9b/32.png) [@Rinke](https://discourse.openehr.org/u/Rinke)\
**Post date:** [7 May 2021 15:55 UTC](https://discourse.openehr.org/t/help-needed-with-openehr-gdl/1537/1 "2021-05-07T15:55:40Z")

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Hi all,

I’m a Dutch clinical informatics PDEng student. As part of my studies I am currently designing (and hopefully developing) a decision support tool to be used in a healthcare department.

What I would like to do is to translate a natural language clincal guideline (in the format: if patient had this in the past, then advice this/perform this) into a computer interpretable guideline, which can then be used in a decision support tool. Of course I could just program if-then-else-rules in any language, but I rather use an standardized approach for this, with reusable models, concepts etc.  
During my preliminary research I’ve read about a few languages (e.g. FHIR clinical reasoning module, Proforma, Asbru etc.) that could do that, but openEHR (with GDL) appeals to me the most because of it’s well-thought-out approach and available tools.

As a start I’ve been following this guideline: [GDL2 Guideline Tutorial I – BMI – Guideline Definition Language (GDL)](https://gdl-lang.org/the-project/guides-tutorials/gdl2/gdl2-guideline-tutorial-bmi-openehr/)  
I’ve followed every step and double checked everything, but unfortunately I do not get any Execution results. Does anyone have the same issue or knows what I am doing wrong? See image below and attached guideline file:

 ![image](https://discourse.openehr.org/uploads/default/original/2X/7/7d958bbd323e84d19240f9ca613c9b23e3bc8061.png)

Additional question:  
Once I’ve this working. What tools could I use to execute the guidelines? Ideally I would integrate this in a Python application, is that possible?

Thanks!

Regards,  
Rinke  
[Test\_BMI.v0.gdl2.json](https://discourse.openehr.org/uploads/short-url/rLDNYH32l81HUMtrGoDD8VdV1Td.json) (4.4 KB)

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**Author:** ![Rinke](https://discourse.openehr.org/letter_avatar_proxy/v4/letter/r/59ef9b/32.png) [@Rinke](https://discourse.openehr.org/u/Rinke)\
**Post date:** [8 May 2021 12:11 UTC](https://discourse.openehr.org/t/help-needed-with-openehr-gdl/1537/2 "2021-05-08T12:11:42Z")

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I discovered the answer to my first question. TLDR; null values aren’t allowed, check for them.

After trying to reupload the guideline file into the gdl2-editor I received the following error message:  
 ![image](https://discourse.openehr.org/uploads/default/original/2X/4/46f27717ea8acc53f13fb5cca302f08e45e89aa2.png)

After looking at the gdl file it turns out, somehow a predicate with _max(null)_ slipped in there, which is not allowed, causing the execution to fail:  
 ![image](https://discourse.openehr.org/uploads/default/original/2X/2/231cebc75ff45e5aaad9167ea80979e67865903d.png)  
Removing the predicate made the execution run succesfully.

Lesson learned: when execution in editor fails look for _null_ in the code or try re-loading the GDL

The latter question remains:

> [@Rinke](#):
>
> Additional question:  
> Once I’ve this working. What tools could I use to execute the guidelines? Ideally I would integrate this in a Python application, is that possible?

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**Author:** ![thomas.beale](https://discourse.openehr.org/user_avatar/discourse.openehr.org/thomas.beale/32/35_2.png) [@thomas.beale](https://discourse.openehr.org/u/thomas.beale)\
**Post date:** [8 May 2021 17:07 UTC](https://discourse.openehr.org/t/help-needed-with-openehr-gdl/1537/3 "2021-05-08T17:07:36Z")

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> [@Rinke](#):
>
> During my preliminary research I’ve read about a few languages (e.g. FHIR clinical reasoning module, Proforma, Asbru etc.) that could do that, but openEHR (with GDL) appeals to me the most because of it’s well-thought-out approach and available tools.

For academic purposes, you may want to have a look at the Task Planning and Decision Language (TP/DL) specs, in the [PROC component](https://specifications.openehr.org/releases/PROC/latest). The DL part is emerging, so it’s more to look at where we are going in the future. You might find [this discussion](https://discourse.openehr.org/t/dl-vs-gdl2-purpose-and-difference/1485) useful.

GDL is established and deployed, has tools etc, so for doing any real implementations, I’d use that.

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**Author:** ![Rinke](https://discourse.openehr.org/letter_avatar_proxy/v4/letter/r/59ef9b/32.png) [@Rinke](https://discourse.openehr.org/u/Rinke)\
**Post date:** [8 May 2021 17:40 UTC](https://discourse.openehr.org/t/help-needed-with-openehr-gdl/1537/4 "2021-05-08T17:40:29Z")

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Thanks for your repsonse Thomas. I’ll definitely have a look at it!

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**Author:** ![Rob](https://discourse.openehr.org/user_avatar/discourse.openehr.org/rob/32/2311_2.png) [@Rob](https://discourse.openehr.org/u/Rob)\
**Post date:** [1 November 2022 10:25 UTC](https://discourse.openehr.org/t/help-needed-with-openehr-gdl/1537/5 "2022-11-01T10:25:50Z")

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Cool! Ik kwam via via hier uit. Dit project nog steeds up and running?