Defines the Service Provider Interface for pluggable JShell execution engines. The JShell core tracks and compiles Snippets then sends them (represented in a wrapper class) to the execution engine for loading, and in the case of executable Snippets, execution. The JShell implementation includes a default execution engine (currently a remote process which is JDI controlled). By implementing the ExecutionControl interface and its generating class, an implementation of the ExecutionControlProvider interface, and installing it with JShell.Builder.executionEngine(String) other execution engines can be used. Where the passed String is an ExecutionControl spec.

The ExecutionControl spec is the ExecutionControlProvider name optionally followed by a parameter specification. The syntax of the spec is:

 spec   := name : params
        | name
 name   := identifier
 params := param , params
        | param
        |
 param  := identifier ( value )
 

Where 'name' is the ExecutionControlProvider name. Where 'param' is a Map key from ExecutionControlProvider.defaultParameters() and the parenthesized value; See, for example, JdiExecutionControlProvider. Where 'identifier' is a sequence of Java identifier part characters from the Basic Multilingual Plane.

For example:

• local
• jdi:hostname(localhost)
• failover:1(jdi),2(jdi:launch(true),timeout(3000)),3(local)