Decision Toolkit

Overview

Decision Toolkit is a suite of tools designed to build, evaluate and test decision models.

Decision Toolkit is constructed based on the Decision Model and Notation (DMN™) specification, which is an industry standard governed by the Object Management Group (OMG®).

Decision Toolkit aims to be performant, reliable, and fully compliant with the DMN™ specification, ensuring accurate evaluation of decision models. All tools are implemented in Rust, a programming language known for its security, efficiency and reliability.

Decision Toolkit offers a range of features, including DMN™ model evaluation, decision table evaluation, and FEEL expression evaluation. It also includes functionality for parsing, validating, and recognizing DMN™ models, decision tables, and FEEL expressions. Users can test DMN™ models, decision tables, and FEEL expressions, and export them to HTML format.

Decision Toolkit provides a comprehensive set of tools for decision model evaluation and testing, leveraging the DMN™ specification and Rust programming language to ensure high performance, reliability and portability.

Main features:

Evaluation of DMN models
Evaluation of decision tables
Evaluation of FEEL expressions
Parsing and validating DMN models
Parsing and recognizing decision tables
Parsing and validating FEEL expressions
Testing DMN models
Testing decision tables
Testing FEEL expressions
Exporting DMN models to HTML
Exporting decision tables to HTML
Exporting FEEL expressions to HTML

📗 NOTE: Current version of this book assumes you’re using Decision Toolkit in version 0.0.4 or later. Please visit Installation chapter to learn how to install or update Decision Toolkit.

Project status

Decision Toolkit is production ready, but there are still some features that may be subject to change or refinement, based on testing and user feedback. We welcome users to try Decision Toolkit out and provide feedback or suggestions to improve its usability or performance.

Installation

Decision Toolkit ships as a single executable without any additional dependencies.

Binary version of Decision Toolkit may be obtained in the following ways:

downloaded directly from GitHub releases, or
built and installed from source using Cargo.

Downloading Decision Toolkit from released versions

Head to GitHub releases.
Expand the Assets section in selected release version.
Download the binary of your choice, according to the operating system you need.

💡 HINT: Names of released binary files contain version number and operating system name like dsntk-0.0.4-linux-x86_64. To proceed with the examples presented in this book, just rename the downloaded binary to:

dsntk for Linux and macOS,

dsntk.exe for Windows.

Installing Decision Toolkit using Cargo

Install Cargo and run:

$ cargo install dsntk

Getting started

Decision Toolkit provides a set of examples ready to play with.

To install examples in examples directory, enter:

$ dsntk exs examples

For a more detailed description of exs command, please refer to Saving examples.

Evaluate example FEEL expression

$ cd ./examples/e1
$ dsntk efe e1.ctx e1.feel

For a more detailed description of efe command, please refer to Evaluating FEEL expressions.

Evaluate example DMN model

$ cd ./examples/e2
$ dsntk edm e2.ctx e2.dmn -i "Greeting Message"

"Hello John Doe"

For a more detailed description of edm command, please refer to Evaluating DMN models.

Evaluate example decision table

$ cd ./examples/e3
$ dsntk edt e3.ctx e3.dtb

0.15

For a more detailed description of edt command, please refer to Evaluating decision tables.

Run Decision Toolkit as a service

$ cd ./examples/e2
$ dsntk srv -v -H 127.0.0.1 -D .

Found 1 model.
Loaded 1 model.
Deployed 1 invocable.

Deployed invocables:
  io/dsntk/2_0001/compliance-level-2-test-0001/Greeting%20Message

dsntk 127.0.0.1:22022

Switch to another terminal and enter:

$ curl -s -d "{\"Full Name\":\"John Doe\"}" \
       -H "Content-Type: application/json" \
       -X POST http://127.0.0.1:22022/evaluate/io/dsntk/2_0001/compliance-level-2-test-0001/Greeting%20Message

{"data":"Hello John Doe"}

For a more detailed description of srv command, please refer to Serving DMN models.

Command-line commands

-h --help

Print this message or the help of the given subcommand(s):

$ dsntk -h

$ dsntk --help

-V --version

Print version information.

$ dsntk -V

$ dsntk --version

srv

Runs Decision Toolkit as a service. To display all available options of the srv command, enter:

$ dsntk help srv

For a more detailed description of srv command, please refer to Serving DMN models.

edm

Evaluates DMN model. To display all available options of the edm command, enter:

$ dsntk help edm

For a more detailed description of edm command, please refer to Evaluating DMN models.

edt

Evaluates decision table. To display all available options of the edt command, enter:

$ dsntk help edt

For a more detailed description of edt command, please refer to Evaluating decision tables.

efe

Evaluates FEEL expression. To display all available options of the efe command, enter:

$ dsntk help efe

For a more detailed description of efe command, please refer to Evaluating FEEL expressions.

pdm

Parses DMN model. To display all available options of the pdm command, enter:

$ dsntk help pdm

For a more detailed description of pdm command, please refer to Parsing DMN models.

pdt

Parses decision table. To display all available options of the pdt command, enter:

$ dsntk help pdt

For a more detailed description of pdt command, please refer to Parsing decision tables.

pfe

Parses FEEL expression. To display all available options of the pfe command, enter:

$ dsntk help pfe

For a more detailed description of pfe command, please refer to Parsing FEEL expressions.

tdm

Tests DMN model. To display all available options of the tdm command, enter:

$ dsntk help tdm

For a more detailed description of tdm command, please refer to Testing DMN models.

tdt

Tests decision table. To display all available options of the tdt command, enter:

$ dsntk help tdt

For a more detailed description of tdt command, please refer to Testing decision tables.

tfe

Tests FEEL expression. To display all available options of the fte command, enter:

$ dsntk help tfe

For a more detailed description of tfe command, please refer to Testing FEEL expressions.

xdm

Exports DMN model. To display all available options of the xdm command, enter:

$ dsntk help xdm

For a more detailed description of xdm command, please refer to Exporting DMN models.

xdt

Exports decision table. To display all available options of the xdt command, enter:

$ dsntk help xdt

For a more detailed description of xdt command, please refer to Exporting decision tables.

xfe

Exports FEEL expression. To display all available options of the xfe command, enter:

$ dsntk help xfe

For a more detailed description of xfe command, please refer to Exporting FEEL expressions.

rdt

Recognizes decision table. To display all available options of the rdt command, enter:

$ dsntk help rdt

For a more detailed description of rdt command, please refer to Recognizing decision tables.

exs

Saves the examples. To display all available options of the exs command, enter:

$ dsntk help exs

For a more detailed description of exs command, please refer to Saving examples.

Serving DMN models

The core function of Decision Toolkit is serving DMN models. The DMN™ specification precisely defines XML interchange format of decision models. XML files containing decision models are loaded and processed by Decision Toolkit server and exposed as a set of JSON API endpoints. Each endpoint represents a single invocable defined in the decision model. Calling an endpoint is equivalent to executing a decision, business knowledge model or decision service.

To explain in details, how to run and use the Decision Toolkit server (a.k.a. DMN runtime), we assume that Decision Toolkit examples are saved in examples directory and the current directory contains ONLY examples directory:

$ ls
examples

Running Decision Toolkit server

To run Decision Toolkit server, enter the following command:

$ dsntk srv

Found 1 model.
Loaded 1 model.
Deployed 1 invocable.
dsntk 0.0.0.0:22022

Decision Toolkit server is started, accepts connections from all available network interfaces 0.0.0.0 (default) and listens on port 22022 (default). During startup, the Decision Toolkit server scans current working directory (default) and its subdirectories, and searches for decision models stored in XML files having .dmn extension.

During the scanning, in the current working directory, the Decision Toolkit server has found examples directory containing one subdirectory named e2 with decision model file named e2.dmn. This file was loaded and one invocable from this file was deployed — a decision named Greeting Message.

This invocable can be evaluated by calling the endpoint:

examples/e2/io/dsntk/2_0001/compliance-level-2-test-0001/Greeting%20Message

The list of all deployed invocables with endpoint names can be displayed during Decision Toolkit server startup by specifying the option -v or --verbose, like shown below:

$ dsntk srv -v

Found 1 model.
Loaded 1 model.
Deployed 1 invocable.

Deployed invocables:
  examples/e2/io/dsntk/2_0001/compliance-level-2-test-0001/Greeting%20Message

dsntk 0.0.0.0:22022

Evaluating the invocable

Having the Decision Toolkit server started, the deployed invocable can be evaluated by calling an endpoint with required input data, using curl for example:

$ curl -s -d "{\"Full Name\":\"John Doe\"}" \
       -H "Content-Type: application/json" \
       -X POST http://0.0.0.0:22022/evaluate/examples/e2/io/dsntk/2_0001/compliance-level-2-test-0001/Greeting%20Message

{"data":"Hello John Doe"}

The Decision Toolkit version of a hello world program could look like this:

$ curl -s -d "{\"Full Name\":\"world\"}" \
       -H "Content-Type: application/json" \
       -X POST http://127.0.0.1:22022/evaluate/examples/e2/io/dsntk/2_0001/compliance-level-2-test-0001/Greeting%20Message

{"data":"Hello world"}

Endpoint names

The common endpoint for evaluating invocables exposed by Decision Toolkit server is named:

evaluate

The full URL of the endpoint is built from the following parts:

protocol:

http:// or https://
host address, like:

0.0.0.0 or 127.0.0.1 or my.domain.com
common endpoint name:

evaluate
directory names where the file containing DMN model was found during scanning:

examples/e2
model namespace converted to RDNN-like path:

io/dsntk/2_0001/compliance-level-2-test-0001
invocable name:

Greeting Message

All parts put together, give the following URL of the endpoint:

http://127.0.0.1:22022/evaluate/examples/e2/io/dsntk/2_0001/Greeting%20Message

📗 NOTE: While not all characters are legal in URL, there is %20 between Greeting and Message, which in percent-encoding represents a space. See RFC3986 for more details.

Evaluating DMN models

🚧 work in progress 🚧

Evaluating decision tables

🚧 work in progress 🚧

Evaluating FEEL expressions

🚧 work in progress 🚧

Parsing DMN models

🚧 work in progress 🚧

Parsing decision tables

🚧 work in progress 🚧

Parsing FEEL expressions

🚧 work in progress 🚧

Testing DMN models

🚧 work in progress 🚧

Testing decision tables

🚧 work in progress 🚧

Testing FEEL expressions

🚧 work in progress 🚧

Exporting DMN models

🚧 work in progress 🚧

Exporting decision tables

🚧 work in progress 🚧

Exporting FEEL expressions

🚧 work in progress 🚧

Recognizing decision tables

🚧 work in progress 🚧

Saving examples

Decision Toolkit provides a set of examples ready to play with.

To install examples in examples directory, enter:

$ dsntk exs examples

The resulting structure of directories and files should be similar to the one shown below:

$ tree .
.
└── examples
    ├── e1
    │   ├── e1.ctx
    │   └── e1.feel
    ├── e2
    │   ├── e2.ctx
    │   └── e2.dmn
    └── e3
        ├── e3.ctx
        └── e3.dtb

5 directories, 6 files

Commands cheat sheet

	DMN MODEL	FEEL EXPRESSION	DECISION TABLE	EXAMPLES
EVALUATE	edm	efe	edt
PARSE	pdm	pfe	pdt
TEST	tdm	tfe	tdt
EXPORT	xdm	xfe	xdt
RECOGNIZE			rdt
SERVE	srv
SAVE				exs

Containerization

Docker

Dockerfile

FROM scratch

# copy the binary file of Decision Toolkit to container root directory
COPY ./target/x86_64-unknown-linux-musl/release/dsntk /

# copy example DMN model to container root directory
COPY ./dsntk/src/examples/e2/e2.dmn /

# start DSNTK as a service and display all deployed invocables
CMD ["/dsntk", "srv", "--verbose"]

docker.sh

#!/usr/bin/env bash

# container name
NAME=dsntk

# container version
VERSION=0.0.3

# stop existing Docker container
docker stop $NAME

# remove stopped Docker container
docker rm $NAME

# remove existing Docker image
docker rmi "$(docker images | grep "^$NAME " | awk '{print $3}')"

# build the Decision Toolkit
cargo +stable build --release --target x86_64-unknown-linux-musl

# build new Docker image
docker build -t $NAME:$VERSION .

# start new Docker container
docker run --name $NAME -d -p 22022:22022 $NAME:$VERSION

# display logs from running Docker container
docker logs -f $NAME

# press Ctrl+C to stop following the log file ;-)

command

$ ./docker.sh

  .
  . (log from executed commands)
  .
Found 1 model.
Loaded 1 model.
Deployed 1 invocable.

Deployed invocables:
  io/dsntk/2_0001/compliance-level-2-test-0001/Greeting%20Message

dsntk 0.0.0.0:22022

$ docker ps

result

CONTAINER ID   IMAGE        COMMAND                  CREATED         STATUS         PORTS                     NAMES
fcb45779ce7d   dsntk:0.0.3  "/dsntk srv --verbose"   2 minutes ago   Up 2 minutes   0.0.0.0:22022->22022/tcp  dsntk

Podman

🚧 work in progress 🚧

FEEL

Arithmetic

Addition

1 + 1

a + b

x + y

Subtraction

1 - 1

a - b

x - y

Multiplication

1 * 1

a * b

x * y

Division

1 / 1

a / b

x / y

Exponentiation

2 ** 3

a ** b

x ** y

Negation

- 1

- a

- x

Built-in functions

abs
after
all
any
append
before
ceiling
coincides
concatenate
contains
count
date
date and time
day of week
day of year
decimal
distinct values
duration
during
ends with
even
exp
finished by
finishes
flatten
floor
get entries
get value
includes
index of
insert before
is
list contains
log
lower case
matches
max
mean
meets
median
met by
min
mode
modulo
month of year
not
number
odd
overlaps
overlaps after
overlaps before
product
remove
replace
reverse
sort
split
sqrt
started by
starts
starts with
stddev
string
string length
sublist
substring
substring after
substring before
sum
time
union
upper case
week of year
years and months duration

License

Decision Toolkit is licensed under either of

MIT license (see LICENSE-MIT) or
Apache License, Version 2.0 (see LICENSE and NOTICE)

at your option.

Contributing

Any contributions to Decision Toolkit are greatly appreciated. If you would like to get involved, please don't hesitate to reach out to us. The source files from which the Decision Toolkit book is generated can be found on GitHub.

References

Versions

This document covers version 0.0.4 (or later) of Decision Toolkit.

This document covers version 1.4 of DMN™ specification.

This document version is 0.0.12.

The Decision Toolkit Book

Downloading Decision Toolkit from released versions

Installing Decision Toolkit using Cargo

Run Decision Toolkit as a service

Running Decision Toolkit server