Run code as a Neo4j extension with GraalVM

Neo4j extension to execute various languages with Cypher.

Setup steps (basic GraalVM and Neo4j install):

1. Download Neo4j community server from neo4j.com.

2. Follow download instructions to set up the database and start it.

3. Download and install GraalVM SDK. GraalVM docs shows one way, but I used SDKMAN! to install it and set GraalVM’s Java (currently 20.3.0.r11-grl) as my default SDK.

4. Install any GraalVM languages you intend to use with the GraalVM Updater (gu). Use command syntax gu install <language>. Note: there may be a couple of other steps for dependencies to run a language, see the docs for each language.

5. Create and start an instance of Neo4j (bin/neo4j start).

Steps to run the examples:

1. Open the file folder where you installed the database (we’ll use this in a minute).

2. Clone this repository, open in your preferred IDE.

3. Build the project, then run mvn clean package (either at command line or through your IDE). This will create a .jar file in the target folder.

4. In your IDE or project folder, copy the .jar file (neo4j-graalvm-polyglot-1.0-SNAPSHOT.jar) and paste it in the /plugins folder where Neo4j is installed.

5. If already started, restart Neo4j.

6. Open a Neo4j Browser window (web browser and go to localhost:7474).

7. Run some test commands to see how it works!

   • Example 1: CALL polyglot.run('js', '"hello"')

   • Example 2: CALL polyglot.run('js','print("hello")') (print messages go to neo4j.log output)

   • Example 3: CALL polyglot.run('python','CALL polyglot.run('python', 'import math; totalEntities = 3000; callsNeeded = int(math.ceil(totalEntities / 100)); callsNeeded');')

   • Languages accepted as first parameter: llvm, R, js, python, ruby