<?xml version="1.0" encoding="UTF-8"?><!-- -*- sgml-indent-step: 1 -*- -->
<!--
The contents of this file are subject to the terms of the Common Development
and Distribution License (the License). You may not use this file except in
compliance with the License.

You can obtain a copy of the License at http://www.netbeans.org/cddl.html
or http://www.netbeans.org/cddl.txt.

When distributing Covered Code, include this CDDL Header Notice in each file
and include the License file at http://www.netbeans.org/cddl.txt.
If applicable, add the following below the CDDL Header, with the fields
enclosed by brackets [] replaced by your own identifying information:
"Portions Copyrighted [year] [name of copyright owner]"

The Original Software is NetBeans. The Initial Developer of the Original
Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
Microsystems, Inc. All Rights Reserved.
-->
<!DOCTYPE api-answers PUBLIC "-//NetBeans//DTD Arch Answers//EN" "../../nbbuild/antsrc/org/netbeans/nbbuild/Arch.dtd" [
  <!ENTITY api-questions SYSTEM "../../nbbuild/antsrc/org/netbeans/nbbuild/Arch-api-questions.xml">
]>

<api-answers
  question-version="1.25"
  module="Utilities"
  author="jtulach@netbeans.org"
>

  &api-questions;

 <answer id="arch-overall">
  <p>
    This module contains general classes needed in NetBeans, extensions to
    basic JRE contepts, useful methods and other 
    <api group="java" name="UtilitiesAPI" category="official" type="export" url="@TOP@/org/openide/util/doc-files/api.html" /> 
    classes.
  </p>
  
  <p>
    Also this module defines the <a href="@TOP@/org/openide/util/Lookup.html">
    Lookup</a> which the NetBeans way for dynamic registration 
    and lookup of 
    components in our modularized component system. It allows lookup and discovery 
    of features by description of their interfaces. The classes are devided 
    into two parts. The 
    <api group="java" name="LookupAPI" type="export" category="official" url="@TOP@/org/openide/util/lookup/doc-files/lookup-api.html">
    allows the discovery</api> and the 
    <api group="java" name="LookupSPI" type="export" category="official" url="@TOP@/org/openide/util/lookup/doc-files/lookup-spi.html">
    simplifies creation and registration of own lookup objects</api>.
  </p>
 </answer>


 <answer id="arch-quality">
  <p>
   There is a lot of unit tests in 
   <a href="http://www.netbeans.org/source/browse/openide/util/test/unit/src/">CVS</a>.
  </p>
 </answer>

 <answer id="arch-time">
  <p>
   The module has been around since 1997 and is stilly improved
   from time to time.
  </p>
 </answer>



 <answer id="arch-usecases">
  
    There is a great introduction to Lookup and its usage in its 
    <a href="@TOP@/org/openide/util/Lookup.html">javadoc</a>. Here is just
    a list of frequently asked or interesting questions slowly expanding as
    people ask them:
    
    <h3>Lookup faq:</h3>
    
    <usecase id="lookup-on-certain-platform" name="How to specify that a service in Lookup should be available only on Windows?" >
<em><b>Q:</b>
Most of the time I specify interfaces that I want to add to the Lookup class in the layer.xml file. 
But, let's say I have a platform-specific interface (something on Windows only, for instance).</em>
<p>
<em>
How can I specify (in the xml, or programmatically) that this service should only be added to the Lookup if the platform is Windows?
</em>>
</p>
In general there are three ways to achieve this.
<ul>
    <li><p>It is possible to write a specific module and enable it only on windows.
    See <a href="@org-openide-modules@/org/openide/modules/doc-files/api.html#how-os-specific">os specific modules</a> documentation.
    Then you can put a registration of your instance into your module's 
    <a href="@TOP@/org/openide/util/doc-files/api.html#service-lookup">META-INF/services</a> directory and it 
    will be available only on Windows.</p>
    </li>
    
    <li><p>Another possibility that does not require new module, but which executes 
    a code on startup (which may have performance implications) is to use <code>methodvalue</code>
    attribute. Register your instance in layer using <code>your-Object.instance</code> file
    as described at 
    <a href="@TOP@/org/openide/util/doc-files/api.html#ido-methodvalue">services
    </a> documentation and in your factory method either return the instance 
    your want or <code>null</code> depending on result of <a href="@TOP@/org/openide/util/Utilities.html#isWindows()">
    Utilities.isWindows()</a> call.</p>
    </li>
                <li>
                    <p>
                        In some cases, the interface for which you will register an implementation permits a
                        no-operation semantics. For example, <code>InstalledFileLocator.locate(...)</code> can
                        return a valid <code>File</code>, or null. You could always register an
                        <code>InstalledFileLocator</code> instance yet disable it on non-Windows platforms
                        (always returning null).
                    </p>
                </li>
</ul>

    </usecase>
    
    <usecase id="lookup-extension-point" name="How shall I write an extension point for my module?" >
    <p>
        <em><b>Q:</b>
        I have more modules one of them providing the core functionality and
        few more that wish to extend it. What is the right way to do it?
        How does the Netbeans platform declare such extension point? 
        </em>
    </p>

    <p>
    
    Start with declaring an extension interface in your
    core module and put it into the module's <em>public packages</em>. Imagine
    for example that the core module is in JAR file <code>org-my-netbeans-coremodule.jar</code>
    and already contains in manifests line like 
    <code>OpenIDE-Module: org.my.netbeans.coremodule/1</code> and wants 
    to display various tips of the day provided by other modules and thus defines:
    </p><pre> 
<span class="java-keywords">package</span> <span class="java-identifier">org</span><span class="java-operators">.</span><span class="java-identifier">my</span><span class="java-operators">.</span><span class="java-identifier">netbeans</span><span class="java-operators">.</span><span class="java-identifier">coremodule</span><span class="java-operators">;</span>

<span class="java-keywords">public</span> <span class="java-keywords">interface</span> <span class="java-identifier">TipsOfTheDayProvider</span> <span class="java-operators">{</span>
    <span class="java-keywords">public</span> <span class="java-identifier">String</span> <span class="java-layer-method">provideTipOfTheDay</span> <span class="java-operators">(</span><span class="java-operators">)</span><span class="java-operators">;</span>
<span class="java-operators">}</span>
</pre><p>
    And in its manifest adds line 
    <code>OpenIDE-Module-Public-Packages: org.my.netbeans.coremodule.*</code>
    to specify that this package contains exported API and shall be 
    accessible to other modules.
    </p>
    <p>
    When the core module is about to display the tip of the day it can ask
    the system for all registered instances of the <code>TipsOfTheDayProvider</code>,
    randomly select one of them:
    </p><pre>
<span class="java-keywords">import</span> <span class="java-identifier">java</span><span class="java-operators">.</span><span class="java-identifier">util</span><span class="java-operators">.</span><span class="java-identifier">Collection</span><span class="java-operators">;</span>
<span class="java-keywords">import</span> <span class="java-identifier">java</span><span class="java-operators">.</span><span class="java-identifier">util</span><span class="java-operators">.</span><span class="java-identifier">Collections</span><span class="java-operators">;</span>
<span class="java-keywords">import</span> <span class="java-identifier">org</span><span class="java-operators">.</span><span class="java-identifier">openide</span><span class="java-operators">.</span><span class="java-identifier">util</span><span class="java-operators">.</span><span class="java-identifier">Lookup</span><span class="java-operators">;</span>

<a href="@TOP@org/openide/util/Lookup.Result.html"><span class="java-identifier">Lookup</span><span class="java-operators">.</span><span class="java-identifier">Result</span></a> <span class="java-identifier">result</span> <span class="java-operators">=</span> <a href="@TOP@org/openide/util/Lookup.html"><span class="java-identifier">Lookup</span></a><span class="java-operators">.</span><span class="java-layer-method">getDefault</span> <span class="java-operators">(</span><span class="java-operators">)</span><span class="java-operators">.</span><span class="java-layer-method">lookup</span> <span class="java-operators">(</span><span class="java-keywords">new</span> <a href="@TOP@org/openide/util/Lookup.Template.html"><span class="java-identifier">Lookup</span><span class="java-operators">.</span><span class="java-layer-method">Template</span></a> <span class="java-operators">(</span><span class="java-identifier">TipsOfTheDayProvider</span><span class="java-operators">.</span><span class="java-keywords">class</span><span class="java-operators">)</span><span class="java-operators">)</span><span class="java-operators">;</span>
<span class="java-identifier">Collection</span> <span class="java-identifier">c</span> <span class="java-operators">=</span> <span class="java-identifier">result</span><span class="java-operators">.</span><a href="@TOP@org/openide/util/Lookup.Result.html#allInstances()"><span class="java-layer-method">allInstances</span></a> <span class="java-operators">(</span><span class="java-operators">)</span><span class="java-operators">;</span>
<span class="java-identifier">Collections</span><span class="java-operators">.</span><span class="java-layer-method">shuffle</span> <span class="java-operators">(</span><span class="java-identifier">c</span><span class="java-operators">)</span><span class="java-operators">;</span>
<span class="java-identifier">TipsOfTheDayProvider</span> <span class="java-identifier">selected</span> <span class="java-operators">=</span> <span class="java-operators">(</span><span class="java-identifier">TipsOfTheDayProvider</span><span class="java-operators">)</span><span class="java-identifier">c</span><span class="java-operators">.</span><span class="java-layer-method">iterator</span> <span class="java-operators">(</span><span class="java-operators">)</span><span class="java-operators">.</span><span class="java-layer-method">next</span> <span class="java-operators">(</span><span class="java-operators">)</span><span class="java-operators">;</span>
</pre><p>    
    and then display the tip. Simple, trivial, just by the usage of 
    <a href="@TOP@org/openide/util/Lookup.html">Lookup</a> interface once 
    creates a registry that other modules can enhance. But such enhancing 
    of course requires work on the other side. Each module that would like
    to register its <code>TipsOfTheDayProvider</code> needs to depend on the 
    core module - add 
    <code>OpenIDE-Module-Module-Dependencies: org.my.netbeans.coremodule/1</code>
    into its manifest and write a class with its own implementation of the
    provider:</p><pre>
<span class="java-keywords">package</span> <span class="java-identifier">org</span><span class="java-operators">.</span><span class="java-identifier">my</span><span class="java-operators">.</span><span class="java-identifier">netbeans</span><span class="java-operators">.</span><span class="java-identifier">extramodule</span><span class="java-operators">;</span>

<span class="java-keywords">class</span> <span class="java-identifier">ExtraTip</span> <span class="java-keywords">implements</span> <span class="java-identifier">TipsOfTheDayProvider</span> <span class="java-operators">{</span>
    <span class="java-keywords">public</span> <span class="java-identifier">String</span> <span class="java-layer-method">provideTipOfTheDay</span> <span class="java-operators">(</span><span class="java-operators">)</span> <span class="java-operators">{</span>
        <span class="java-keywords">return</span> <span class="java-string-literal">"Do you know that in order to write extension point you should use Lookup?"</span><span class="java-operators">;</span>
    <span class="java-operators">}</span>
<span class="java-operators">}</span>
</pre><p>
    Then, the only necessary thing is to register such class by using the 
    J2SE standard <api name="ProviderRegistrationMechanism"
  type="import"
  category="standard"
  group="java" /> into plain text file
    <code>META-INF/services/org.my.netbeans.coremodule.TipsOfTheDayProvider</code>
    in the module JAR containing just one line: </p><pre>
org.my.netbeans.extramodule.ExtraTip
</pre><p>    
    and your modules are now ready to communicate
    using your own <em>extension point</em>.
    </p>
    
    </usecase>
    

 </answer>



 <answer id="arch-what">
  <p>
    Described in the <a href="@TOP@/architecture-summary.html#answer-arch-overall">overall</a> answer.
  </p>
 </answer>



 <answer id="compat-i18n">
  <p>
   There is not much things to localize in this module, so it is properly localized.
   But it is good to note that the module adds <api name="BrandingSupport" category="official" group="property" type="export" url="@TOP@/org/openide/util/NbBundle.html">
   which is similar to localization but also supports changes of resorces 
   for application build on top of NetBeans. This is handled by our
   class <a href="@TOP@/org/openide/util/NbBundle.html">NbBundle</a> which 
   reimplements the JDK's standard <a href="@JDK@/java/util/ResourceBundle.html">ResourceBundle</a>
   to to take branding into the consideration.
   </api>. 
  </p>
 </answer>



 <answer id="compat-standards">
  <p>
    The default lookup registration follows the JDK's 
    <api name="ProviderRegistrationMechanism"
      type="import"
      category="standard"
      url="http://java.sun.com/j2se/1.3/docs/guide/jar/jar.html#Provider%20Configuration%20File"
      group="java" 
    />
    but enhances it to also support the 
    <api 
      name="ProviderRegistrationRemoval" 
      type="export" 
      category="devel" 
      url="@TOP@/org/openide/util/doc-files/api.html#service-lookup"
      group="java" 
    />. 
  </p>
 </answer>

 <answer id="compat-version">
  <p>
   This module has no settings. 
  </p>
 </answer>



 <answer id="dep-jre">
  <p>
   Currently JRE 1.4 is needed.
  </p>
 </answer>



 <answer id="dep-jrejdk">
  <p>
   JRE is enough.
  </p>
 </answer>


 <answer id="dep-nb">
  <p>
   This module is independent of other NetBeans modules and can be used 
   independently. For better interaction with UI parts of NetBeans it however
   indirectly communicates with <a href="@org-openide-awt@/overview-summary.html">UI Utilities</a>
   module using <api name="AWTBridge" category="private" group="java" type="export" 
   url="http://www.netbeans.org/source/browse/openide/util/src/org/netbeans/modules/openide/util/AWTBridge.java">
   a class that is looked up in <a href="@TOP@/org/openide/util/Lookup.html#getDefault()">Lookup.getDefault()</a>
   and if registered can provide better UI elements for <a href="@JDK@/javax/swing/Action.html">Action</a>s.
   </api>
   
  </p>
 </answer>

 <answer id="dep-non-nb">
  <p>
   Reexports XML APIs so needs some XML parser implementation, but as one 
   is provided in any 1.4 java, it in fact has no dependencies except on JRE. 
  </p>
 </answer>

 <answer id="dep-platform">
  <p>
   Platform independent.
  </p>
 </answer>


 <answer id="deploy-dependencies">
  <p>
  OpenIDE-Module-Module-Dependencies: org.openide.util > @SPECIFICATION-VERSION@
  </p>
 </answer>



 <answer id="deploy-jar">
  <p>
   <api category="devel" group="java.io.File" name="FileLocation" type="export" >
   the JAR file is located in platform cluster under <code>lib/org-openide-util.jar</code>
   </api>.
  </p>
 </answer>



 <answer id="deploy-nbm">
  <p>
   No reason to not deploy nbm.
  </p>
 </answer>


 <answer id="deploy-packages">
  <p>
   Yes, public packages declared.
  </p>
 </answer>



 <answer id="deploy-shared">
  <p>
   Module is on real java classpath and as such it has to be in the shared directory.
  </p>
 </answer>


 <answer id="exec-ant-tasks">
  <p>
   No.
  </p>
 </answer>



 <answer id="exec-classloader">
  <p>
   No, we do not create own classloader.
  </p>
 </answer>



<!--
        <question id="exec-component" when="impl">
            Is execution of your code influenced by any (string) property
            of any of your components?
            
            <hint>
            Often <code>JComponent.getClientProperty</code>, <code>Action.getValue</code>
            or <code>PropertyDescriptor.getValue</code>, etc. are used to influence
            a behavior of some code. This of course forms an interface that should
            be documented. Also if one depends on some interface that an object
            implements (<code>component instanceof Runnable</code>) that forms an
            API as well.
            </hint>
        </question>
-->
 <answer id="exec-component">
  <ul>
    <li><api name="HelpID" category="standard" group="property" type="export" url="@TOP@/org/openide/util/HelpCtx.html">
        read from <a href="@JDK@/javax/swing/JComponent.html">JComponent</a>.getClientProperty
        to simulate the standard javahelp behaviour and extract the help id for given component.
        </api>
    </li>

    <li><api name="iconBase" category="standard" group="property" type="import" >
        <a href="@TOP@/org/openide/util/actions/SystemAction.html">SystemAction</a> 
        reacts to expected requests from <a href="@org-openide-awt@/overview-summary.html">UI Utilities</a>
        module for <code>iconBase</code> property by returning value based on its
        result of its <code>iconResource()</code> method.
        </api>
    </li>
        
    <li>
        <api name="org.openide.util.SharedClassObject.initialize" category="private" group="property" type="export">
        For purposes of 
        <a href="@org-openide-options@/org/openide/options/SystemOption.html">SystemOption</a>
        the
        <a href="@TOP@/org/openide/util/SharedClassObject.html">SharedClassObject</a>
        handles
        <code>getProperty ("org.openide.util.SharedClassObject.initialize")</code> 
        in a special way, by returning 
        <code>null</code> if initialization is not running and <code>Boolean.TRUE</code> if 
        it is.
        </api>
    </li>
    
    <li><api name="OpenIDE-Transmodal-Action" category="devel" group="property" type="export" >
        <a href="@TOP@/org/openide/util/actions/CallbackSystemAction.html">CallbackSystemAction</a> 
        checks whether <code>action.getValue("OpenIDE-Transmodal-Action")</code>
        returns <code>Boolean.TRUE</code> to enable it in dialogs, otherwise
        the action is disabled when there is an open dialog.
        </api>
    </li>
    
    
  </ul>
 </answer>



<!--
        <question id="exec-introspection" when="impl">
            Does your module use any kind of runtime type information (<code>instanceof</code>,
            work with <code>java.lang.Class</code>, etc.)?
            <hint>
            Check for cases when you have an object of type A and you also
            expect it to (possibly) be of type B and do some special action. That
            should be documented. The same applies on operations in meta-level
            (Class.isInstance(...), Class.isAssignableFrom(...), etc.).
            </hint>
        </question>
-->
 <answer id="exec-introspection">
  <p>
   <a href="@TOP@/org/openide/util/Utilities.html">Utilities</a> provide wrapper
   for java beans introspection. <api category="private" group="java" name="ParserFactory" type="import" >
       The <a href="@TOP@/org/openide/xml/XMLUtil.html">XMLUtil</a> class is loading
       a class from <code>core/core.jar</code> to initialize the correct parser factory.
       This is a fix for <a href="http://www.netbeans.org/issues/show_bug.cgi?id=68942">issue 68942</a>.
   </api>
   </p>
 </answer>



 <answer id="exec-privateaccess">
  <p>
  No.
  </p>
 </answer>

 <answer id="exec-process">
  <p>
   No external processes executed.
  </p>
 </answer>


 <answer id="exec-property">
  <ul>
    <li><api type="export" group="property" name="netbeans.screen.insets" category="private">
    Influences results of Utilities.getUsableScreenBounds</api>.</li>
    <li><api type="export" group="property" name="netbeans.taskbar.height" category="private">
    Influences results of Utilities.getUsableScreenBounds</api>.</li>
    <li>
        <api type='import' group="property" name="line.separator" category="standard" >
        used on few places
        </api>.
    </li>
    
    <li>
    <api type="export" group="property" name="org.openide.util.Lookup" category="devel">
        checked by the initialization of the 
        <a href="@TOP@/org/openide/util/Lookup.html#getDefault()">Lookup.getDefault()</a>
        and can
        contain name of a class that extends <code>org.openide.util.Lookup</code> and
        has public constructor, that should be instantiated and returned from 
        <a href="@TOP@/org/openide/util/Lookup.html#getDefault()">Lookup.getDefault()</a>
        the class will be loaded by 
        <a href="@JDK@/java/lang/Thread.html#getContextClassLoader()">
        Thread.currentThread().getContextClassLoader()</a>
        classloader the first time <code>Lookup.getDefault</code> is invoked.
        <p/>
        The property can also contain value <code>"-"</code> which means to completely
        disable the lookup instantiation and return <a href="@TOP@/org/openide/util/Lookup.html#EMPTY">Lookup.EMPTY</a>
        from <a href="@TOP@/org/openide/util/Lookup.html#getDefault()">Lookup.getDefault()</a>.
        <p/>
        If the property is unspecified, the default <code>MetaInfServicesLookup</code>
        is constructed for <code>Thread.currentThread().getContextclassLoader()</code>
        that implements the <a href="architecture-summary.html#answer-compat-standards">JDK's standard</a>. If, by 
        a chance an instance of 
        <a href="@TOP@/org/openide/util/Lookup.Provider.html">Lookup.Provider</a>
        is found
        in there, its lookup is returned as result. Otherwise the <code>MetaInfServicesLookup</code>
        is the result of <a href="@TOP@/org/openide/util/Lookup.html#getDefault()">Lookup.getDefault()</a>.
    </api>
    </li>
    
  </ul>
 </answer>



<!--
        <question id="exec-reflection" when="impl">
            Does your code use Java Reflection to execute other code?
            <hint>
            This usually indicates a missing or insufficient API in the other
            part of the system. If the other side is not aware of your dependency
            this contract can be easily broken.
            </hint>
        </question>
-->
 <answer id="exec-reflection">
  <p>
   <api category="devel" group="java" name="SharedClassObject.setAccessible" type="export" url="@TOP@/org/openide/util/SharedClassObject.html">
   used to instantiate subclasses. 
   </api>. 
   <api category="devel" group="java" name="WeakListener.setAccessible" type="export" url="@TOP@/org/openide/util/WeakListeners.html">
   used to call the remove method using reflection
   </api>. 
   <api category="devel" group="java" name="Lookups.metaInfServices" type="export" url="@TOP@/org/openide/util/lookup/Lookups.html#metaInfServices(java.lang.ClassLoader)">
   calls constructor of registered classes using reflection
   </api>. 
   <api category="private" group="lookup" name="ActionManagerInvocation" type="export" >
    because of the API separation, <a href="@TOP@/org/openide/util/actions/CallableSystemAction.html">CallableSystemAction</a> uses lookup for <code>ActionsBridge</code>
    provided by <code>org-openide-actions</code> module
    when looking for <a href="@org-openide-actions@/org/openide/actions/ActionManager.html">org.openide.actions.ActionManager</a> implementation.
    </api>.

  </p>
 </answer>



<!--
        <question id="exec-threading" when="impl">
            What threading models, if any, does your module adhere to?
            <hint>
                If your module calls foreign APIs which have a specific threading model,
                indicate how you comply with the requirements for multithreaded access
                (synchronization, mutexes, etc.) applicable to those APIs.
                If your module defines any APIs, or has complex internal structures
                that might be used from multiple threads, declare how you protect
                data against concurrent access, race conditions, deadlocks, etc.,
                and whether such rules are enforced by runtime warnings, errors, assertions, etc.
                Examples: a class might be non-thread-safe (like Java Collections); might
                be fully thread-safe (internal locking); might require access through a mutex
                (and may or may not automatically acquire that mutex on behalf of a client method);
                might be able to run only in the event queue; etc.
                Also describe when any events are fired: synchronously, asynchronously, etc.
                Ideas: <a href="http://core.netbeans.org/proposals/threading/index.html#recommendations">Threading Recommendations</a> (in progress)
            </hint>
        </question>
-->
 <answer id="exec-threading">
  <p>
   XXX no answer for exec-threading
  </p>
 </answer>



 <answer id="format-clipboard">
  <p>
    <a href="@TOP@/org/openide/util/datatransfer/MultiTransferObject.html">MultiTransferObject</a> can be 
    used in <a href="@JDK@/java/awt/datatransfer/Transferable.html">Transferable</a> to represent content
    composed of multiple independent 
    <a href="@JDK@/java/awt/datatransfer/Transferable.html">Transferable</a>s.
  </p>
 </answer>



 <answer id="format-dnd">
  <p>
  The same as for clipboard.
  </p>
 </answer>

 <answer id="format-types">
  <p>
    The <a href="http://java.sun.com/j2se/1.3/docs/guide/jar/jar.html#Provider%20Configuration%20File">META-INF/services/...</a> files.
    <api name="TranslateNames" category="official" type="export" group="java.io.File" 
    url="@TOP@/org/openide/util/Utilities.html#translate(java.lang.String)">
    <a href="@TOP@/org/openide/util/Utilities.html#translate(java.lang.String)">Utilities.translate</a> 
    reads <code>META-INF/netbeans/translate.names</code> files from JARs</api>.
  </p>
 </answer>



 <answer id="lookup-lookup">
    <ul>
    <li><api name="LookupInitializationLookup" category="devel" group="lookup" type="export" url="#property-org.openide.util.Lookup">
    during 
    initialization of the <a href="@TOP@/org/openide/util/Lookup.html#getDefault()">Lookup.getDefault()</a>
    the <a href="@TOP@/org/openide/util/Lookup.Provider.html">Lookup.Provider</a>
    is being searched</api>.
    </li>
    
    <li><api name="LookupSharedClassObject" category="devel" group="lookup" type="export">
    singleton subclasses of <a href="@TOP@/org/openide/util/SharedClassObject.html">SharedClassObject</a> 
    are searched for using Lookup.
    </api>.</li>

    <li><api name="LookupContextGlobalProvider" category="stable" group="lookup" type="export">
    <a href="@TOP@/org/openide/util/Utilities.html#actionsGlobalContext()">actionsGlobalContext</a>
    searches for <a href="@TOP@/org/openide/util/ContextGlobalProvider.html">ContextGlobalProvider</a> in 
    <a href="@TOP@/org/openide/util/Lookup.html#getDefault()">Lookup.getDefault()</a>.
    The provider is usually provided by <a href="@org-openide-windows@/overview-summary.html">window 
    system implementation</a>.
    </api>.</li>

    <li><api name="LookupEntityCatalog" category="devel" group="lookup" type="export">
    <a href="@TOP@/org/openide/xml/EntityCatalog.html">EntityCatalog</a> 
    delegates its methods to all instances of <a href="@TOP@/org/openide/xml/EntityCatalog.html">EntityCatalog</a>s
    found in Lookup
    </api>.</li>
    
    <li><api name="LookupErrorManager" category="devel" group="lookup" type="export">
    <a href="@TOP@/org/openide/ErrorManager.html">ErrorManager</a> 
    delegates its methods to all instances of <a href="@TOP@/org/openide/ErrorManager.html">ErrorManager</a>s
    found in Lookup
    </api>.</li>
            
    <li><api name="LookupClassLoader" category="devel" group="lookup" type="export">
    Nearly all resource looking functions and reflective code
    uses <a href="@JDK@/java/lang/ClassLoader.html">ClassLoader</a>
    obtained from <a href="@TOP@/org/openide/util/Lookup.html#getDefault()">Lookup.getDefault()</a>
    for loading system wide resources.
    </api>.</li>
    
    </ul>
 </answer>



<!--
        <question id="lookup-register" when="final">
            Do you register anything into lookup for other code to find?
            <hint>
            Do you register using layer file or using <code>META-INF/services</code>?
            Who is supposed to find your component?
            </hint>
        </question>
-->
 <answer id="lookup-register">
  <p>
   No.
  </p>
 </answer>



<!--
        <question id="lookup-remove" when="final">
            Do you remove entries of other modules from lookup?
            <hint>
            Why? Of course, that is possible, but it can be dangerous. Is the module
            your are masking resource from aware of what you are doing?
            </hint>
        </question>
-->
 <answer id="lookup-remove">
  <p>
   No.
  </p>
 </answer>



<!--
        <question id="perf-exit" when="final">
            Does your module run any code on exit?
        </question>
-->
 <answer id="perf-exit">
  <p>
   Nothing.
  </p>
 </answer>



<!--
        <question id="perf-huge_dialogs" when="final">
            Does your module contain any dialogs or wizards with a large number of
            GUI controls such as combo boxes, lists, trees, or text areas?
        </question>
-->
 <answer id="perf-huge_dialogs">
  <p>
   No.
  </p>
 </answer>



<!--
        <question id="perf-limit" when="init">
            Are there any hard-coded or practical limits in the number or size of
            elements your code can handle?
        </question>
-->
 <answer id="perf-limit">
  <p>
    The default implementation of the <code>MetaInfServicesLookup</code> just 
    keeps hashmap between queried classes and their implementations. The amount
    of memory is linear to amount of registered classes, but of course we 
    are not counting the memory occupied by the instances which the lookup 
    creates, that can be arbitrary.
  </p>
 </answer>



<!--
        <question id="perf-mem" when="final">
            How much memory does your component consume? Estimate
            with a relation to the number of windows, etc.
        </question>
-->
 <answer id="perf-mem">
  <p>
   There are no big data structures. The amount of memory occupied by
   instances of <a href="@TOP@/org/openide/util/lookup/AbstractLookup.html">AbstractLookup</a> 
   is measured by unit tests.
  </p>
 </answer>



<!--
        <question id="perf-menus" when="final">
            Does your module use dynamically updated context menus, or
            context-sensitive actions with complicated and slow enablement logic?
            <hint>
                If you do a lot of tricks when adding actions to regular or context menus, you can significantly
                slow down display of the menu, even when the user is not using your action. Pay attention to
                actions you add to the main menu bar, and to context menus of foreign nodes or components. If
                the action is conditionally enabled, or changes its display dynamically, you need to check the
                impact on performance. In some cases it may be more appropriate to make a simple action that is
                always enabled but does more detailed checks in a dialog if it is actually run.
            </hint>
        </question>
-->
 <answer id="perf-menus">
  <p>
   There are no menus.
  </p>
 </answer>



<!--
        <question id="perf-progress" when="final">
            Does your module execute any long-running tasks?
            
            <hint>Long running tasks should never block 
            AWT thread as it badly hurts the UI
            <a href="http://performance.netbeans.org/responsiveness/issues.html">
            responsiveness</a>.
            Tasks like connecting over
            network, computing huge amount of data, compilation
            be done asynchronously (for example
            using <code>RequestProcessor</code>), definitively it should 
            not block AWT thread.
            </hint>
        </question>
-->
 <answer id="perf-progress">
  <p>
   Actions declared as <a href="@TOP@/org/openide/util/actions/CallableSystemAction.html#asynchronous()">CallableSystemAction.asynchronous()</a> 
   are executed outside of AWT thread on a dedicated request processor one.
  </p>
 </answer>



<!--
        <question id="perf-scale" when="init">
            Which external criteria influence the performance of your
            program (size of file in editor, number of files in menu, 
            in source directory, etc.) and how well your code scales?
            <hint>
            Please include some estimates, there are other more detailed 
            questions to answer in later phases of implementation. 
            </hint>
        </question>
-->
 <answer id="perf-scale">
  <p>
   Lookup code scales linearily.
  </p>
 </answer>



<!--
        <question id="perf-spi" when="init">
            How the performance of the plugged in code will be enforced?
            <hint>
            If you allow foreign code to be plugged into your own module, how
            do you enforce that it will behave correctly and quickly and will not
            negatively influence the performance of your own module?
            </hint>
        </question>
-->
 <answer id="perf-spi">
  <p>
   No enforcing is done.
  </p>
 </answer>



<!--
        <question id="perf-startup" when="final">
            Does your module run any code on startup?
        </question>
-->
 <answer id="perf-startup">
  <p>
   No.
  </p>
 </answer>



<!--
        <question id="perf-wakeup" when="final">
            Does any piece of your code wake up periodically and do something
            even when the system is otherwise idle (no user interaction)?
        </question>
-->
 <answer id="perf-wakeup">
  <p>
   No. 
  </p>
 </answer>



<!--
        <question id="resources-file" when="final">
            Does your module use <code>java.io.File</code> directly?
            
            <hint>
            NetBeans provide a logical wrapper over plain files called 
            <code>org.openide.filesystems.FileObject</code> that
            provides uniform access to such resources and is the preferred
            way that should be used. But of course there can be situations when
            this is not suitable.
            </hint>
        </question>
-->
 <answer id="resources-file">
  <p>
   No.
  </p>
 </answer>



<!--
        <question id="resources-layer" when="final">
            Does your module provide own layer? Does it create any files or
            folders in it? What it is trying to communicate by that and with which 
            components?
            
            <hint>
            NetBeans allows automatic and declarative installation of resources 
            by module layers. Module register files into appropriate places
            and other components use that information to perform their task
            (build menu, toolbar, window layout, list of templates, set of
            options, etc.). 
            </hint>
        </question>
-->
 <answer id="resources-layer">
  <p>
   No.
  </p>
 </answer>



<!--
        <question id="resources-mask" when="final">
            Does your module mask/hide/override any resources provided by other modules in
            their layers?
            
            <hint>
            If you mask a file provided by another module, you probably depend
            on that and do not want the other module to (for example) change
            the file's name. That module shall thus make that file available as an API
            of some stability category.
            </hint>
        </question>
-->
 <answer id="resources-mask">
  <p>
   No.
  </p>
 </answer>



<!--
        <question id="resources-read" when="final">
            Does your module read any resources from layers? For what purpose?
            
            <hint>
            As this is some kind of intermodule dependency, it is a kind of API.
            Please describe it and classify according to 
            <a href="http://openide.netbeans.org/tutorial/api-design.html#categories">
            common stability categories</a>.
            </hint>
        </question>
-->
 <answer id="resources-read">
  <p>
   No.
  </p>
 </answer>



<!--
        <question id="security-grant" when="final">
            Does your code grant additional rights to some other code?
            <hint>Avoid using a class loader that adds extra
            permissions to loaded code unless really necessary.
            Also note that your API implementation
            can also expose unneeded permissions to enemy code by
            calling AccessController.doPrivileged().</hint>
        </question>
-->
 <answer id="security-grant">
  <p>
   No security permitions manipulated.
  </p>
 </answer>



<!--
        <question id="security-policy" when="final">
            Does your functionality require modifications to the standard policy file?
            <hint>Your code might pass control to third-party code not
            coming from trusted domains. This could be code downloaded over the
            network or code coming from libraries that are not bundled
            with NetBeans. Which permissions need to be granted to which domains?</hint>
        </question>
-->
 <answer id="security-policy">
  <p>
   No security permissions manipulated.
  </p>
 </answer>

</api-answers>
