LinkScript

Introduction

A LinkScript is a reusable, named Groovy script that can be chained with other LinkScripts to build composable server-side logic. Each LinkScript holds a Groovy body and a set of arcs that connect it to other LinkScripts, so that complex behavior can be assembled from small, independently testable units instead of one large script.

LinkScripts are managed from the App > LinkScript menu.

LinkScript grid view

Creating a LinkScript

Open the LinkScript menu and click New.

LinkScript form

Main Fields

Field Type Description

Name

String (required, unique)

Technical name used to reference and run the LinkScript.

Transactional

Boolean switch (default: false)

When enabled, the script runs within a transaction.

Description

HTML

Free-text documentation of what the script does.

Body

The Body tab holds the Groovy code of the script, edited with a syntax-highlighting code editor.

LinkScript body editor

If the body does not end with an explicit return on its last line, all variables of the current context plus every variable defined in the body are implicitly returned. Whether returned implicitly or explicitly, the result is injected into the context under the name defined on the arc that called the script.

Arcs

Arcs connect a LinkScript to other LinkScripts and control how results are composed. A LinkScript has two arc panels:

Panel Role

Dependency arcs

LinkScripts that are run before this script. Their results are injected into the context under the arc’s name and made available to the body.

Output arcs

LinkScripts that are run after this script, taking this script’s result as part of their context.
LinkScript dependency arcs

Each arc has the following fields:

Field Description

Name

The binding name under which the called script’s result is injected into the context. Must match the pattern ^[a-z][a-zA-Z0-9]*$ (defaults to result when left empty).

Condition

An optional Groovy condition. The arc is only followed when the condition evaluates to true.

To LinkScript

The target LinkScript to run. A new LinkScript can be created inline from this field.

Dependency arcs are evaluated in ascending Sequence order (set by reordering the rows in the grid).

Running and Testing

A Test button is available both on the grid and on the form toolbar. It opens a test dialog where you provide bindings for the script.

Test LinkScript dialog

  • Each binding has a Parameter name and an Expression.

  • An expression is evaluated as a Groovy expression if it starts with eval:; otherwise it is treated as a plain string.

  • The parameter list can be pre-filled from the variables detected in the script body.

When you click Test, the LinkScript is executed with the provided bindings and the result is displayed.

Built-in Functions

Inside a LinkScript body, the following helper functions are available:

Function Description

echo(objects…​)

Concatenates the string representation of the given objects, separated by spaces.

inject(serviceClass)

Returns the managed bean for the given service class, so a LinkScript can call application services.

run(linkScriptName, argument)

Runs another LinkScript by name with the given argument map and returns its final result.

Recursion Limit

LinkScripts can call each other (directly through run() or transitively through arcs). To guard against runaway recursion, the engine stops with a "Too many recursions." error once the configured maximum recursion depth is exceeded. The limit is read from the Studio application settings (AppSettingsStudioService.getMaximumRecursion()).

Technical Details

LinkScripts are stored in the following entities:

Entity Field Description

LinkScript

name

Unique technical name

LinkScript

transactional

Whether the script runs in a transaction

LinkScript

body

Groovy script body

LinkScript

dependencyArcs / outputArcs

One-to-many links to LinkScriptArc

LinkScriptArc

name / conditionScript / toLinkScript / sequence

Binding name, optional condition, target script and ordering

LinkScriptBinding

parameter / expression

Transient bindings used by the test dialog

Key backend components:

  • LinkScriptService.run(name, context) — Entry point that runs a LinkScript by name

  • LinkScriptServiceImpl — Resolves dependency arcs by sequence, evaluates arc conditions, injects results into the context, and applies the recursion limit

  • LinkScriptGroovyEvaluator — Groovy evaluation of script bodies and arc conditions

  • LinkScriptController — Handles the test dialog (setBindings, run)

  • LinkScriptFunctions — Built-in echo, inject, and run helpers