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31 <p>The scripting API consists of interfaces and classes that define
32 Java <font size=1><sup>TM</sup></font> Scripting Engines and provides
33 a framework for their use in Java applications. This API is intended
34 for use by application programmers who wish to execute programs
35 written in scripting languages in their Java applications. The
36 scripting language programs are usually provided by the end-users of
37 the applications.
38 </p>
39 <p>The main areas of functionality of <code>javax.script</code>
40 package include
41 </p>
42 <ol>
43 <li><p><b>Script execution</b>: Scripts
44 are streams of characters used as sources for programs executed by
45 script engines. Script execution uses
46 {@link javax.script.ScriptEngine#eval eval} methods of
47 {@link javax.script.ScriptEngine ScriptEngine} and methods of the
48 {@link javax.script.Invocable Invocable} interface.
49 </p>
50 <li><p><b>Binding</b>: This facility
51 allows Java objects to be exposed to script programs as named
52 variables. {@link javax.script.Bindings Bindings} and
53 {@link javax.script.ScriptContext ScriptContext}
54 classes are used for this purpose.
55 </p>
56 <li><p><b>Compilation</b>: This
57 functionality allows the intermediate code generated by the
58 front-end of a script engine to be stored and executed repeatedly.
59 This benefits applications that execute the same script multiple
60 times. These applications can gain efficiency since the engines'
61 front-ends only need to execute once per script rather than once per
62 script execution. Note that this functionality is optional and
63 script engines may choose not to implement it. Callers need to check
64 for availability of the {@link javax.script.Compilable Compilable}
65 interface using an <I>instanceof</I> check.
66 </p>
67 <li><p><b>Invocation</b>: This
68 functionality allows the reuse of intermediate code generated by a
69 script engine's front-end. Whereas Compilation allows entire scripts
70 represented by intermediate code to be re-executed, Invocation
71 functionality allows individual procedures/methods in the scripts to
72 be re-executed. As in the case with compilation, not all script
73 engines are required to provide this facility. Caller has to check
74 for {@link javax.script.Invocable Invocable} availability.
75 </p>
76 <li><p><b>Script engine discovery and Metadata</b>: Applications
77 written to the Scripting API might have specific requirements on
78 script engines. Some may require a specific scripting language
79 and/or version while others may require a specific implementation
80 engine and/or version. Script engines are packaged in a specified
81 way so that engines can be discovered at runtime and queried for
82 attributes. The Engine discovery mechanism is based on the Service
83 discovery mechanism described in the <b>Jar File Specification</b>.
84 Script engine implementing classes are packaged in jar files that
85 include a text resource named
86 <b>META-INF/services/javax.script.ScriptEngineFactory</b>. This
87 resource must include a line for each
88 {@link javax.script.ScriptEngineFactory ScriptEngineFactory}
89 that is packaged in the jar file.
90 {@link javax.script.ScriptEngineManager ScriptEngineManager}
91 includes
92 {@link javax.script.ScriptEngineManager#getEngineFactories getEngineFactories} method to get all
93 {@link javax.script.ScriptEngineFactory ScriptEngineFactory} instances
94 discovered using this mechanism. <code>ScriptEngineFactory</code> has
95 methods to query attributes about script engine.
96 </p>
97 </ol>
98
99 @since 1.6
100
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