Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/allen-ball/ganymede

The Ganymede Kernel is a Jupyter Notebook Java kernel based on the Java Shell tool, JShell.
https://github.com/allen-ball/ganymede

java jupyter-kernel jupyter-notebook

Last synced: about 1 month ago
JSON representation

The Ganymede Kernel is a Jupyter Notebook Java kernel based on the Java Shell tool, JShell.

Awesome Lists containing this project

README

        

[![Ganymede](README/ganymede.png)](https://images.nasa.gov/details-GSFC_20171208_Archive_e002091)

Ganymede: Jupyter Notebook Java Kernel
======================================

The [Ganymede Kernel] is a [Jupyter Notebook] Java [kernel][Jupyter Kernel].
Java code is compiled and interpreted with the Java Shell tool, [JShell].
This kernel offers the following additional features:

* Integrated Project Object Model (POM) for [Apache Maven] artifact
dependency resolution[1](#endnote1)

* Integrated support for [Structured Query Language] (SQL) through [JDBC]
and [jOOQ]

* Integrated support for [JSR 223] scripting languages including:

* [Groovy]
* [Javascript][2](#endnote2)
* [Kotlin]

* Templates (via any of [Thymeleaf], [Markdown] ([CommonMark]) with
[JMustache], [FreeMarker][Apache FreeMarker], and
[Velocity][Apache Velocity])

* Support for [Apache Spark] and [Scala] binary distributions

## Installation

The [Ganymede Kernel] is distributed as a single JAR
([download here][Ganymede Kernel download]).

> :warning:
> Only [Jupyter Notebook] versions before 7 (`<7`) are fully supported at this
> time. See the `Pipfile` in [ganymede-notebooks] for a minimal Python
> configuration.

Java 11 or later is required. In addition to Java, the [Jupyter Notebook]
must be [installed][Jupyter Notebook Installation] first and the `jupyter`
and `python` commands must be on the `${PATH}`. Then the typical (and
minimal) installation command line:

```bash
$ java -jar ganymede-2.1.2.20230910.jar -i
```

The [kernel][Ganymede Kernel] will be configured to use the same `java`
installation as invoked in the install command above. These additional
command line options are supported.

| Option | Action | Default |
| --- | --- | --- |
| --id-prefix=<prefix> | Adds prefix to kernel ID | <none> |
| --id=<id> | Specifies kernel ID | `ganymede-${version}-java-${java.specification.version}` |
| --id-suffix=<suffix> | Adds suffix to kernel ID | <none> |
| --display-name-prefix=<prefix> | Adds prefix to kernel display name | <none> |
| --display-name=<name> | Specifies kernel display name | Ganymede `${version}` (Java `${java.specification.version}`) |
| --display-name-suffix=<suffix> | Adds suffix to kernel display name | <none> |
| --env | Specify NAME=VALUE pair(s) to add to kernel environment | |
| --copy-jar=<boolean> | Copies the [Ganymede Kernel] JAR to the `kernelspec` directory | true |
| --sys-prefix
or --user | Install in the system prefix or user path (see the `jupyter kernelspec install` command). | --user |

The following Java system properties may be configured.

| System Properties | Action | Default(s) |
|-------------------|---------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------|
| maven.repo.local | Configures the local Maven repository | --sys-prefix${jupyter.data}/repository/--user${user.home}/.m2/ |

The following OS environment variables may be configured:

| Environment Variable | Option | Action |
|----------------------|---------------------------|---------------------------------------------------------------------------------------|
| SPARK_HOME | --spark-home=<path> | If configured, the kernel will add the [Apache Spark] JARs to the kernel's classpath. |
| HIVE_HOME | --hive-home=<path> | If configured, the kernel will add the [Apache Hive] JARs to the kernel's classpath. |

For example, a sophisticated configuration to test a snapshot out of a
user's local [Maven][Apache Maven] repository:

```bash
$ export JAVA_HOME=$(/usr/libexec/java_home -v 11)
$ ${JAVA_HOME}/bin/java \
-jar ${HOME}/.m2/repository/ganymede/ganymede/2.2.0-SNAPSHOT/ganymede-2.2.0-SNAPSHOT.jar \
-i --sys-prefix --copy-jar=false \
--id-suffix=spark-3.3.4 --display-name-suffix="with Spark 3.3.4" \
--spark_home=/path/to/spark-home --hive_home=/path/to/hive-home
$ jupyter kernelspec list
Available kernels:
...
ganymede-2.2.0-java-11-spark-3.3.4 /.../share/jupyter/kernels/ganymede-2.2.0-java-11-spark-3.3.4
...
```

would result in the configured
`${jupyter.data}/kernels/ganymede-2.2.0-java-11-spark-3.3.4/kernel.json`
kernelspec:

```json
{
"argv": [
"/Library/Java/JavaVirtualMachines/graalvm-ce-java11-22.3.0/Contents/Home/bin/java",
"--add-opens",
"java.base/jdk.internal.misc=ALL-UNNAMED",
"--illegal-access=permit",
"-Djava.awt.headless=true",
"-Djdk.disableLastUsageTracking=true",
"-Dmaven.repo.local=/Users/ball/Notebooks/.venv/share/jupyter/repository",
"-jar",
"/Users/ball/.m2/repository/dev/hcf/ganymede/ganymede/2.2.0-SNAPSHOT/ganymede-2.2.0-SNAPSHOT.jar",
"-f",
"{connection_file}"
],
"display_name": "Ganymede 2.2.0 (Java 11) with Spark 3.3.4",
"env": {
"JUPYTER_CONFIG_DIR": "/Users/ball/.jupyter",
"JUPYTER_CONFIG_PATH": "/Users/ball/.jupyter:/Users/ball/Notebooks/.venv/etc/jupyter:/usr/local/etc/jupyter:/etc/jupyter",
"JUPYTER_DATA_DIR": "/Users/ball/Library/Jupyter",
"JUPYTER_RUNTIME_DIR": "/Users/ball/Library/Jupyter/runtime",
"SPARK_HOME": "/path/to/spark-home"
},
"interrupt_mode": "message",
"language": "java"
}
```

The [kernel][Ganymede Kernel] makes extensive use of templates and POM
fragments. While not strictly required, the authors suggest that the
[Hide Input] extension is enabled so notebook authors can hide the input
templates and POMs for any finished product. This may be set from the
command line with:

```bash
$ jupyter nbextension enable hide_input/main --sys-prefix
```

(or `--user` as appropriate).

## Features and Usage

The following subsections outline many of the features of the
[kernel][Ganymede Kernel].

### Java

The Java REPL is [JShell] and has all the Java features of the installed
JVM. The minimum required Java version is 11 and subsequent versions are
supported.

The [JShell] environment includes builtin functions implemented through
methods that wrap the `public` methods defined in [NotebookContext] class
annotated with [@NotebookFunction][NotebookFunction]. These functions
include:

| Method | Description |
|---------------------------------------------------------------------------------------------------------------------------|----------------------------------------|
| [print(Object)](https://allen-ball.github.io/ganymede/ganymede/notebook/NotebookContext.html#print(java.lang.Object)) | Render the Object to a Notebook format |
| [display(Object)](https://allen-ball.github.io/ganymede/ganymede/notebook/NotebookContext.html#display(java.lang.Object)) | Render the Object to a Notebook format |
| [asJson(Object)](https://allen-ball.github.io/ganymede/ganymede/notebook/NotebookContext.html#asJson(java.lang.Object)) | Convert argument to JsonNode |
| [asYaml(Object)](https://allen-ball.github.io/ganymede/ganymede/notebook/NotebookContext.html#asYaml(java.lang.Object)) | Convert argument to YAML (String) |

The builtin functions are mostly concerned with "printing" or displaying
(rendering) Objects to multimedia formats. For example, `print(byte[])`
will render the byte array as an image. Integrated renderers for chart and
plot objects include:

* [JFreeChart]

* [Tablesaw] (wrapping [Plotly])

* [XChart]

The [trig.ipynb] notebook demonstrates rendering of an [XChart].

As discussed in the next section, the magic identifier for java is `%%java`.
A cell identified with `%%java` with no code will provide a table of variable
bindings in the context with types and values. The types are links to the
corresponding javadoc (if known).




NameTypeValue


$$ganymede.notebook.NotebookContextNotebookContext(super=ganymede.notebook.NotebookContext@af7e376)
by_stateorg.apache.spark.sql.Dataset<Row>[Country/Region: string, Province/State: string ... 1 more field]
chartorg.knowm.xchart.PieChartorg.knowm.xchart.PieChart@767f4a69
countries_aggregatedorg.apache.spark.sql.Dataset<Row>[Date: date, Country: string ... 3 more fields]
datesorg.apache.spark.sql.Dataset<Row>[Date: date]
intervalorg.apache.spark.sql.Row[2020-01-22,2022-04-16]
key_countries_pivotedorg.apache.spark.sql.Dataset<Row>[Date: date, China: int ... 7 more fields]
readerorg.apache.spark.sql.DataFrameReaderorg.apache.spark.sql.DataFrameReader@5a88849
referenceorg.apache.spark.sql.Dataset<Row>[UID: int, iso2: string ... 10 more fields]
sessionorg.apache.spark.sql.SparkSessionorg.apache.spark.sql.SparkSession@1b6683c4
snapshotorg.apache.spark.sql.Dataset<Row>[Country/Region: string, Deaths: int]
time_series_19_covid_combinedorg.apache.spark.sql.Dataset<Row>[Date: date, Country/Region: string ... 4 more fields]
us_confirmedorg.apache.spark.sql.Dataset<Row>[Admin2: string, Date: date ... 3 more fields]
us_deathsorg.apache.spark.sql.Dataset<Row>[Admin2: string, Date: date ... 3 more fields]
us_simplifiedorg.apache.spark.sql.Dataset<Row>[Date: date, Admin2: string ... 4 more fields]
worldwide_aggregateorg.apache.spark.sql.Dataset<Row>[Date: date, Confirmed: int ... 3 more fields]


### Magics

Cell magic commands are identified by `%%` starting the first line of a code
cell. The list of available magic commands is shown below. The default
cell magic is `java`.




Name(s)Description



!, script
Execute script with the argument command


bash
Execute script with 'bash' command


classpath
Add to or print JShell classpath


env
Add/Update or print the environment


freemarker
FreeMarker template evaluator


groovy
Execute code in groovy REPL


html
HTML template evaluator


java
Execute code in Java REPL


javascript, js
Execute code in javascript REPL


kotlin
Execute code in kotlin REPL


magics
Lists available cell magics


markdown
Markdown template evaluator


mustache, handlebars
Mustache template evaluator


perl
Execute script with 'perl' command


pom
Define the Notebook's Project Object Model


ruby
Execute script with 'ruby' command


scala
Execute code in scala REPL


sh
Execute script with 'sh' command


spark-session
Configure and start a Spark session


sql
Execute code in SQL REPL


thymeleaf
Thymeleaf template evaluator


velocity
Velocity template evaluator



`script`, `bash`, `perl`, etc. are executed by creating a [Process]
instance. [`groovy`][Groovy], [`javascript`][Javascript],
[`kotlin`][Kotlin], etc. are provided through their respective [JSR 223]
interfaces.[3](#endnote3) Dependency and classpath
management are provided with the `classpath` and `pom` magics and are
described in detail in a subsequent subsection. `thymeleaf` and `html`
provide [Thymeleaf] template evaluation.

The [kernel][Ganymede Kernel] does not implement any "line" magics.

### Dependency and Classpath Management

The `classpath` magic adds JAR and directory paths to the [JShell]
classpath. The `pom` magic resolves and downloads [Maven][Apache Maven]
artifacts and then adds those artifacts to the classpath.

The [trig.ipynb] notebook demonstrates the use of the `pom` magic to resolve
the `org.knowm.xchart:xchart:LATEST` artifact and its transient dependencies.

```yaml
%%pom
dependencies:
- org.knowm.xchart:xchart:LATEST
```

The POM is expressed in [YAML] and repositories and dependencies may be
expressed. The Notebook's POM may be split across multiple cells since each
repository and dependency is added or merged and dependency resolution is
attempted whenever a `pom` cell is executed. The default/initial Notebook
POM is:

```yaml
repositories:
- id: central
layout: default
url: https://repo1.maven.org/maven2
snapshots:
enabled: false
```

Dependencies may either be expressed in "expanded" YAML or in
`groupId:artifactId[:extension]:version` format:

```yaml
dependencies:
- groupId: groupA
artifactId: groupAartifact1
version: 1.0
- groupB:groupB-artifact2:2.0
```

The specific attributes for repositories and dependencies are defined by the
[Apache Maven Artifact Resolver] classes [RemoteRepository] (with
[RepositoryPolicy]) and [Dependency]. (Note that these classes are slightly
different than their [Maven][Apache Maven] settings counterparts.)

Whenever a JAR is added to the classpath, it is analyzed to determine if its
[Maven coordinates] can be determined and, if they can be determined, the
JAR is added as an artifact to the
[resolver][Apache Maven Artifact Resolver]. The following checks are made
before adding the JAR to the [JShell] classpath:

1. It is a new, unique path

2. No previously resolved artifact with the same `groupId:artifactId` on the
classpath

3. Special heuristics for logging configuration:

a. Ignore `commons-logging:commons-logging:jar`

b. Allow only one of `org.slf4j:jcl-over-slf4j:jar` or
`org.springframework:spring-jcl:jar` to be configured

c. Allow only one of `org.slf4j:slf4j-log4j12:jar` and
`ch.qos.logback:logback-classic:jar` to be configured

Artifacts that fail any of the above checks will be (mostly silently)
ignored. Because only the first version of a resolved artifact is ever
added to the classpath, the [kernel][Ganymede Kernel] must be restarted if a
different version of the same artifact is specified for the change to take
effect.

Finally, the [kernel][Ganymede Kernel] provides special processing to add
artifacts from [Apache Spark] binary distributions. The dependencies for
[Spark SQL][Apache Spark SQL] and corresponding [Scala] compiler artifacts
for currently available Spark binary distributions as resources. The kernel
searches the `${SPARK_HOME}` for JARs for which it has the corresponding
dependencies and then resolves the dependencies from the `${SPARK_HOME}`
hierarchy with the heuristics described above.

### SQL

The [SQL] [Magic] provides the client interface to database servers through
[JDBC] and [jOOQ]. Its usage is as follows:

```
Usage: sql [--[no-]print] [] [] []
[] JDBC Connection URL
[] JDBC Connection Username
[] JDBC Connection Password
--[no-]print Print query results. true by default
```

For example:

```sql
%%sql jdbc:mysql://127.0.0.1:33061/epg?serverTimezone=UTC
SELECT * FROM schedules LIMIT 3;
```

airDateTimestationIDjsondurationmd5programID153394560010139{
"programID" : "EP009370080215",
"airDateTime" : "2018-08-11T00:00:00Z",
"duration" : 3600,
"md5" : "S1UDH1R60Eagc1E3V5Qslw",
"audioProperties" : [ "cc" ],
"ratings" : [ {
"body" : "USA Parental Rating",
"code" : "TVPG"
} ]
}3600S1UDH1R60Eagc1E3V5QslwEP009370080215153394560010142{
"programID" : "EP006062993248",
"airDateTime" : "2018-08-11T00:00:00Z",
"duration" : 3600,
"md5" : "2FQ8y5PsXl1vtxcmUBeppg",
"new" : true,
"audioProperties" : [ "cc" ],
"ratings" : [ {
"body" : "USA Parental Rating",
"code" : "TVPG"
} ]
}36002FQ8y5PsXl1vtxcmUBeppgEP006062993248153394560010145{
"programID" : "EP022439260394",
"airDateTime" : "2018-08-11T00:00:00Z",
"duration" : 1800,
"md5" : "mUewfiqM8+dh24WQg2WfpQ",
"audioProperties" : [ "cc" ]
}1800mUewfiqM8+dh24WQg2WfpQEP022439260394

The [SQL] [Magic] accepts the `--print`/`--no-print` options to print or
suppress query results. If no JDBC URL is specified, the most recently used
connection will be used. The [List] of most recent [jOOQ] [Queries][Query]
are stored in [$$.sql.queries][NotebookContext.SQL.queries] with
[$$.sql.results][NotebookContext.SQL.results] containing the corresponding
[Result]s. For example:

```sql
%%sql --no-print
SELECT COUNT(*) FROM programs;
```

```java
%%java
print($$.sql.results.get(0));
```

count(*)
1024495

[MySQL][MySQL Connectors] and [PostgreSQL][PostgreSQL JDBC Driver] [JDBC]
drivers are provided in the [Ganymede][Ganymede Kernel] runtime.

### Spark

The `spark-session` magic is provided to initialize [Apache Spark]
[sessions][SparkSession].

```
Usage: spark-session [--[no-]enable-hive-if-available] [] []
[] Spark master
[] Spark appName
--[no-]enable-hive-if-available
Enable Hive if available. true by default
```

Its typical usage:

```
%%spark-session local[*] covid-19
# Optional name/value pairs parsed as Properties
```

is roughly equivalent to:

```java
var config = new SparkConf();
/*
* Properties copied to SparkConf instance.
*/
var session =
SparkSession.builder()
.config(config)
.master("local").appName("covid-19")
.getOrCreate();
```

The [SparkSession] can then be accessed in Java and other JVM code with the
[SparkSession.active()] static method.

### Other Laguages ([JSR 223])

The [kernel][Ganymede Kernel] leverages the [java.scripting API] to provide
[`groovy`][Groovy], [`javascript`][Javascript], [`kotlin`][Kotlin], and
[`scala`][Scala].[4](#endnote4)

### Shells

The `script` magic (with the alias `!`) may be used to run an operating
system command with the remaining code in the cell fed to the [Process]'s
standard input. `bash`, `perl`, `ruby`, and `sh` are provided as aliases
for `%%!bash`, `%%!perl`, etc., respectively.

### Templates

A number of templating languages are supported as magics:

* [Markdown] ([CommonMark] preprocessed with [JMustache])
* [Apache FreeMarker]
* [Apache Velocity]
* [JMustache]
* [Thymeleaf]

The following subsections provide examples of the `markdown` and `thymeleaf`
magics but the other template magics are similar. Please refer to the
installation instructions for discussion of enabling the [Hide Input]
extension so only the template output is displayed in the notebook.

### Markdown and JMustache

The template magic `markdown` provides [Markdown] processing with [JMustache]
preprocessing:

```java
%%java
import java.util.stream.Stream;

import static java.util.stream.Collectors.toList;

var fib =
Stream.iterate(new int[] { 0, 1 }, t -> new int[] { t[1], t[0] + t[1] })
.mapToInt(t -> t[0])
.limit(10)
.boxed()
.collect(toList());
```

```java
%%markdown
| Index | Value |
| --- | --- |
{{#fib}}| {{-index}} | {{this}} |
{{/fib}}
```


IndexValue


00
11
21
32
43
55
68
713
821
934

#### Thymeleaf

The template magics `thymeleaf` and `html` offer templating with
[Thymeleaf]. All defined Java variables are bound into the Thymeleaf
context before evaluation. For example (Java implementation detail
removed):

```java
%%java
...
var map = new TreeMap>(Ranking.COMPARATOR.reversed());
...
var rankings = Arrays.asList(Ranking.values());
...
```

```html
%%html






Remaining

```

Would generate:


RoyalFlushA-♤K-♤Q-♤J-♤10-♤


StraightFlushK-♡Q-♡J-♡10-♡9-♡


FourOfAKind8-♤8-♡8-♢8-♧2-♧


FullHouseA-♡A-♢A-♧K-♢K-♧


FlushQ-♢J-♢10-♢9-♢7-♢


Straight7-♤6-♤5-♤4-♤3-♤


ThreeOfAKind6-♡6-♢6-♧3-♧4-♧


TwoPair9-♤9-♧7-♡7-♧5-♧


Pair5-♡5-♢10-♧J-♧2-♢


HighCardQ-♧3-♢4-♢2-♡3-♡



Remaining4-♡2-♤

## Documentation

[Javadoc][Ganymede API Javadoc] is published at
.

## License

[Ganymede Kernel] is released under the
[Apache License, Version 2.0, January 2004].

## Endnotes

[1]
Implemented with [Apache Maven Artifact Resolver].
[↩](#ref1)

[2]
With the built-in Oracle Nashorn engine.
[↩](#ref2)

[3]
[`scala`][Scala] is special cased: It requires additional dependencies be
specified at runtime and is optimized to be used with [Apache Spark].
[↩](#ref3)

[4]
Ibid.
[↩](#ref4)

[Ganymede Kernel]: https://github.com/allen-ball/ganymede
[Ganymede Kernel download]: https://github.com/allen-ball/ganymede/releases/download/v2.1.2.20230910/ganymede-2.1.2.20230910.jar
[Ganymede API Javadoc]: https://allen-ball.github.io/ganymede/index.html?overview-summary.html
[Magic]: https://allen-ball.github.io/ganymede/ganymede/shell/Magic.html
[NotebookContext]: https://allen-ball.github.io/ganymede/ganymede/notebook/NotebookContext.html
[NotebookContext.SQL]: https://allen-ball.github.io/ganymede/ganymede/notebook/NotebookContext.SQL.html
[NotebookContext.SQL.queries]: https://allen-ball.github.io/ganymede/ganymede/notebook/NotebookContext.SQL.html#queries
[NotebookContext.SQL.results]: https://allen-ball.github.io/ganymede/ganymede/notebook/NotebookContext.SQL.html#results
[NotebookFunction]: https://allen-ball.github.io/ganymede/ganymede/notebook/NotebookFunction.html
[SQL]: https://allen-ball.github.io/ganymede/ganymede/shell/magic/SQL.html

[ganymede-notebooks]: https://github.com/allen-ball/ganymede-notebooks
[trig.ipynb]: https://github.com/allen-ball/ganymede-notebooks/blob/trunk/trig.ipynb

[Apache License, Version 2.0, January 2004]: https://www.apache.org/licenses/LICENSE-2.0

[Apache FreeMarker]: https://freemarker.apache.org/

[Apache Hive]: https://hive.apache.org/

[Apache Maven]: https://maven.apache.org/
[Maven coordinates]: https://maven.apache.org/pom.html#Maven_Coordinates

[Apache Maven Artifact Resolver]: https://maven.apache.org/resolver/index.html
[RemoteRepository]: https://maven.apache.org/resolver/maven-resolver-api/apidocs/org/eclipse/aether/repository/RemoteRepository.html?is-external=true
[RepositoryPolicy]: https://maven.apache.org/resolver/maven-resolver-api/apidocs/org/eclipse/aether/repository/RepositoryPolicy.html
[Dependency]: https://maven.apache.org/resolver/maven-resolver-api/apidocs/org/eclipse/aether/graph/Dependency.html?is-external=true

[Apache Spark]: http://spark.apache.org/
[Apache Spark SQL]: https://spark.apache.org/sql/
[SparkSession]: https://spark.apache.org/docs/latest/api/java/org/apache/spark/sql/SparkSession.html
[SparkSession.active()]: https://spark.apache.org/docs/latest/api/java/org/apache/spark/sql/SparkSession.html#active--

[Apache Velocity]: https://velocity.apache.org/

[Groovy]: https://groovy-lang.org/

[Java API]: https://docs.oracle.com/en/java/javase/11/docs/api
[JShell]: https://docs.oracle.com/en/java/javase/11/docs/api/jdk.jshell/jdk/jshell/JShell.html?is-external=true
[List]: https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/List.html?is-external=true
[Process]: https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Process.html

[Javascript]: https://www.oracle.com/technical-resources/articles/java/jf14-nashorn.html

[JDBC]: https://docs.oracle.com/javase/8/docs/technotes/guides/jdbc/

[JFreeChart]: https://github.com/jfree/jfreechart

[JMustache]: https://github.com/samskivert/jmustache

[jOOQ]: https://www.jooq.org/doc/latest/manual
[Query]: https://www.jooq.org/javadoc/latest/org.jooq/org/jooq/Query.html?is-external=true
[Result]: https://www.jooq.org/javadoc/latest/org.jooq/org/jooq/Result.html?is-external=true

[JSR 223]: https://jcp.org/en/jsr/detail?id=223
[java.scripting API]: https://docs.oracle.com/en/java/javase/11/docs/api/java.scripting/module-summary.html

[Jupyter Notebook]: https://jupyter-notebook.readthedocs.io/en/stable/index.html
[Jupyter Notebook Installation]: https://jupyter.readthedocs.io/en/latest/install/notebook-classic.html
[Hide Input]: https://jupyter-contrib-nbextensions.readthedocs.io/en/latest/nbextensions/hide_input/readme.html

[Jupyter Kernel]: https://jupyter-client.readthedocs.io/en/stable/kernels.html

[Kotlin]: https://kotlinlang.org/

[Markdown]: https://en.wikipedia.org/wiki/Markdown
[CommonMark]: https://commonmark.org/

[MySQL Connectors]: https://www.mysql.com/products/connector/

[Plotly]: https://github.com/plotly

[PostgreSQL JDBC Driver]: https://jdbc.postgresql.org/

[Scala]: https://www.scala-lang.org/

[Structured Query Language]: https://en.wikipedia.org/wiki/SQL

[Tablesaw]: https://github.com/jfree/jfreechart

[Thymeleaf]: https://www.thymeleaf.org/index.html

[XChart]: https://github.com/knowm/XChart

[YAML]: https://yaml.org/