Core+ Java Client Example

This repository contains an example Deephaven Core+ Java client application, for use with a Deephaven Enterprise installation.

Gradle configuration

The build.gradle file includes all the required dependencies. Be sure to update the versions in the gradle.properties file in this repository to match the version of your Deephaven installation — the version numbers specified in gradle.properties determine which version of Deephaven libraries are retrieved by Gradle. Additionally, your credentials for Deephaven Artifactory must be available to Gradle. Typically, these are stored in a ~/.gradle/gradle.properties file like the following:

% cat ~/.gradle/gradle.properties
artifactoryUser=<Deephaven Artifactory username>
artifactoryAPIKey=<Deephaven Artifactory password or API key>

Example application

The example class in this repository (org.example.ClientExample) connects and authenticates to a Deephaven cluster ( using either a username and password or a private key file for authentication), then starts a new query worker to run a basic operation and retrieve its result. It also demonstrates connecting to an existing persistent query and retrieving a snapshot of one of the persistent query's tables.

This example serves to demonstrate connecting and authenticating to a Deephaven cluster and obtaining API connections to both new workers and existing persistent queries, but does not cover the extensive functionality of the client API. For further examples of operations supported with Barrage and the Deephaven APIs, please see the example in the basic-java-client repository.

Running the example program

The example application can be run using Gradle, which will set the required JVM arguments. To start the example using a username and password for authentication, run the following command:

./gradlew run --args="https://<Deephaven server address>:<Deephaven port> <username>:<password>"

To retrieve a snapshot of a table from a persistent query, include the <query name> and <table name> arguments as in the following example:

./gradlew run --args="https://<Deephaven server address>:<Deephaven port> <username>:<password> <query name> <table name>"

Instead of providing a username and password, the example can be run with private key authentication by specifying a path to a private key file in place of the <username>:<password> argument, as in the examples below. ( For more information on creating and adding private keys, see How to Create Deephaven Authentication Keys.)

./gradlew run --args="<Deephaven server address>:<Deephaven port> </path/to/keyfile> <query name> <table name>"

./gradlew run --args="https://deephaven.mycompany.net:8123 /home/myusername/my-dh-private-key.txt MyTestQuery table_123"

JVM arguments

When creating your own clients, be sure to set the following JVM arguments:

-DConfiguration.rootFile=dh-defaults.prop
-DDeephavenEnterprise.rootFile=iris-common.prop
--add-opens=java.base/java.nio=ALL-UNNAMED org.example.ClientExample

• The -DConfiguration.rootFile property is used when initializing the application. This is included in the Deephaven dependencies.
• The -DDeephavenEnterprise.rootFile property specifies the Deephaven property file to retrieve from the configuration server, after the client opens its initial connection to the Deephaven server and authenticates.
• The --add-opens option is a JVM argument required to enable the use of certain required Java APIs by reflection.

For example, when running your own Deephaven client, the command will look similar to the following:

java -classpath <classpath> -DDeephavenEnterprise.rootFile=iris-common.prop -DConfiguration.rootFile=dh-defaults.prop --add-opens=java.base/java.nio=ALL-UNNAMED org.example.ClientExample org.example.ExampleClient https://deephaven-prod.mycompany.net:8123 </path/to/keyfile> <query name> <table name>

Please see the Deephaven Enterprise documentation or contact Deephaven support for more information.