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Version: Java (Groovy)

Use Application Mode libraries

This guide shows you how to use the two main libraries for Application Mode scripts, ApplicationContext and ApplicationState. These libraries give you more control over Deephaven's state during launch.

ApplicationContext is a gateway to the application state used during the initial startup of a Deephaven server using Application Mode. This is useful when using complicated scripts that require multiple Python/Groovy files, defined by the file_N fields in the *.app file. Deephaven maintains the state of these classes between each file through the ApplicationContext class.

ApplicationState is used to interact with the Deephaven server within Application Mode. The setField(str: name, T: value) and getField(str: name).value() methods are used to interact with fields on the Deephaven server.

Example​

The following example uses ApplicationContext and ApplicationState to create tables within Deephaven through Application Mode. We use ApplicationContext to grab the current ApplicationState, and then use setField to set the tables within Deephaven.

note

The tables created below are not bound to a global variable. Because of this, they are only useable within an Application Mode script, and not within the Deephaven Console.

If you want to use the tables within the Deephaven Console, you must bind them to a global variable.

import io.deephaven.appmode.ApplicationContext
import io.deephaven.appmode.ApplicationState

def start = { ApplicationState app ->
    size = 42
    app.setField("hello", emptyTable(size))
    app.setField("world", timeTable("00:00:01"))
}

ApplicationContext.initialize(start)