javax/script/package.html

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903N/A<p>The scripting API consists of interfaces and classes that define
903N/AJava <font size=1><sup>TM</sup></font> Scripting Engines and provides
903N/Aa framework for their use in Java applications. This API is intended
903N/Afor use by application programmers who wish to execute programs
903N/Awritten in scripting languages in their Java applications. The
903N/Ascripting language programs are usually provided by the end-users of
903N/Athe applications.
903N/A</p>
903N/A<p>The main areas of functionality of <code>javax.script</code>
903N/Apackage include
903N/A</p>
903N/A<ol>
903N/A    <li><p><b>Script execution</b>: Scripts
903N/A    are streams of characters used as sources for  programs executed by
903N/A    script engines. Script execution uses
903N/A        {@link javax.script.ScriptEngine#eval eval} methods of
903N/A    {@link javax.script.ScriptEngine ScriptEngine} and methods of the
903N/A        {@link javax.script.Invocable Invocable} interface.
903N/A    </p>
903N/A    <li><p><b>Binding</b>: This facility
903N/A    allows Java objects to be exposed to script programs as named
903N/A    variables. {@link javax.script.Bindings Bindings} and
903N/A        {@link javax.script.ScriptContext ScriptContext}
903N/A    classes are used for this purpose.
903N/A    </p>
903N/A    <li><p><b>Compilation</b>: This
903N/A    functionality allows the intermediate code generated by the
903N/A    front-end of a script engine to be stored and executed repeatedly.
903N/A    This benefits applications that execute the same script multiple
903N/A    times. These applications can gain efficiency since the engines'
903N/A    front-ends only need to execute once per script rather than once per
903N/A    script execution. Note that this functionality is optional and
903N/A    script engines may choose not to implement it. Callers need to check
903N/A    for availability of the {@link javax.script.Compilable Compilable}
903N/A        interface using an <I>instanceof</I> check.
    </p>
    <li><p><b>Invocation</b>: This
    functionality allows the reuse of intermediate code generated by a
    script engine's front-end. Whereas Compilation allows entire scripts
    represented by intermediate code to be re-executed, Invocation
    functionality allows individual procedures/methods in the scripts to
    be re-executed. As in the case with compilation, not all script
    engines are required to provide this facility. Caller has to check
    for {@link javax.script.Invocable Invocable} availability.
    </p>
    <li><p><b>Script engine discovery and Metadata</b>: Applications
    written to the Scripting API might have specific requirements on
    script engines. Some may require a specific scripting language
    and/or version while others may require a specific implementation
    engine and/or version. Script engines are packaged in a specified
    way so that engines can be discovered at runtime and queried for
    attributes. The Engine discovery mechanism is based on the Service
    discovery mechanism described in the <b>Jar File Specification</b>.
    Script engine implementing classes are packaged in jar files that
    include a  text resource named
    <b>META-INF/services/javax.script.ScriptEngineFactory</b>. This
    resource must include a line for each
        {@link javax.script.ScriptEngineFactory ScriptEngineFactory}
    that is packaged in the jar file.
        {@link javax.script.ScriptEngineManager ScriptEngineManager}
    includes
        {@link javax.script.ScriptEngineManager#getEngineFactories getEngineFactories} method to get all
    {@link javax.script.ScriptEngineFactory ScriptEngineFactory} instances
        discovered using this mechanism. <code>ScriptEngineFactory</code> has
        methods to query attributes about script engine.
    </p>
</ol>

@since 1.6

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