/*

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

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 *

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 */

/**

<p>The scripting API consists of interfaces and classes that define

Java™ Scripting Engines and provides

a framework for their use in Java applications. This API is intended

for use by application programmers who wish to execute programs

written in scripting languages in their Java applications. The

scripting language programs are usually provided by the end-users of

the applications.

</p>

<p>The main areas of functionality of <code>javax.script</code>

package include

</p>

<ol>

<li><p><b>Script execution</b>: Scripts

are streams of characters used as sources for  programs executed by

script engines. Script execution uses

{@link javax.script.ScriptEngine#eval eval} methods of

{@link javax.script.ScriptEngine ScriptEngine} and methods of the

{@link javax.script.Invocable Invocable} interface.

</p>

<li><p><b>Binding</b>: This facility

allows Java objects to be exposed to script programs as named

variables. {@link javax.script.Bindings Bindings} and

{@link javax.script.ScriptContext ScriptContext}

classes are used for this purpose.

</p>

<li><p><b>Compilation</b>: This

functionality allows the intermediate code generated by the

front-end of a script engine to be stored and executed repeatedly.

This benefits applications that execute the same script multiple

times. These applications can gain efficiency since the engines'

front-ends only need to execute once per script rather than once per

script execution. Note that this functionality is optional and

script engines may choose not to implement it. Callers need to check

for availability of the {@link javax.script.Compilable Compilable}

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</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-provider

loading facility described in the {@link java.util.ServiceLoader} class.

{@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

*/

package javax.script;