<?xml version="1.0" encoding="UTF-8"?>
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-->
<!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="1.12"
  module="Settings"
  author="rmatous@netbeans.org"
>

  &api-questions;


<!--
        
     <question id="arch-what">
            What is this project good for?
            <hint>
            Please provide here few lines describing the the project, 
            what problem it should solve, provide links to documentation, 
            specifications, etc.
            </hint>
        </question>
-->
<answer id="arch-what">
Settings are persistent objects with a set of properties, that should be available via lookup.  
Properties are expected to be changed. Implementation of setting doesn't care about persistence issues, which
is responsibility of settings infrastructure.  XML persistence support is provided in a standalone autoload module core-settings.jar.
But a typical setting is a system option, which uses serialization at the moment. Also service types must be mentioned here.
Service type can be desribed as typed a named settings.
<ul>
<li>
<api group="java" name="SettingsAPI" type="export" category="official" url="@org-openide-util@/org/openide/util/doc-files/api.html#settings"/>
</li><li>
<api group="java" name="ServicesAPI" type="export" category="official" url="@org-openide-util@/org/openide/util/doc-files/api.html#service-lookup"/>
</li><li>
<api group="java" name="OptionsAPI" type="export" category="official" url="@org-openide-options@/org/openide/options/doc-files/api.html"/>
</li><li>
<api group="java" name="XmlSettingsPersistence" type="export" category="official" url="@org-netbeans-modules-settings@/org/netbeans/spi/settings/doc-files/api.html"/>
</li>
</ul>
</answer>


<!--
        
     <question id="compat-i18n">
            Is your module correctly internationalized?
            <hint>
            Correct internationalization means that it obeys instuctions 
            at <a href="http://www.netbeans.org/devhome/docs/i18n/index.html">
            NetBeans I18N pages</a>.
            </hint>
        </question>
-->
<answer id="compat-i18n">
Yes
</answer>



<!--
        
     <question id="compat-standards">
            Does the module implement or define any standards? Is the 
            implementation exact or does it deviate somehow?
        </question>
-->
<answer id="compat-standards">
No
</answer>



<!--
        
     <question id="compat-version">
            Can your module coexist with earlier and future
            versions? Can you correctly read all old settings? Will future
            versions be able to read your current settings? Can you read
            or politely ignore settings stored by a future version?
            
            <hint>
            Very helpful for reading settings is to store version number
            there, so future versions can decide whether how to read/convert
            the settings and older versions can ignore the new ones.
            </hint>
        </question>
-->
<answer id="compat-version">
Yes. 
</answer>



<!--
        
     <question id="dep-jre">
            Which version of JRE do you need (1.2, 1.3, 1.4, etc.)?
            <hint>
            It is expected that if your module runs on 1.x that it will run 
            on 1.x+1 if no, state that please. Also describe here cases where
            you run different code on different versions of JRE and why.
            </hint>
        </question>
-->
<answer id="dep-jre">
JRE 1.3
</answer>



<!--
        
     <question id="dep-jrejdk">
            Do you require the JDK or is the JRE enough?
        </question>
-->
<answer id="dep-jrejdk">
JRE is enough
</answer>



<!--
        
     <question id="dep-nb">
            What other NetBeans projects does this one depend on?
            <hint>
            If you want, describe such projects as imported API using
            the <code>&lt;api name="identification" type="import or export" category="stable" url="where is the description" /&gt;</code>
            </hint>
        </question>
-->
<answer id="dep-nb">
<defaultanswer generate='none' />    
It uses various kinds of API's:
<ul>
<li>
    <api 
        name="FilesystemsAPI"
        type="import"
        category="official"
        url="@org-openide-filesystems@/org/openide/filesystems/doc-files/api.html"
				group="java"     />
</li>
<li>
    <api 
        name="LoadersAPI"
        type="import"
        category="official"
        url="@org-openide-loaders@/org/openide/loaders/doc-files/api.html"
        group="java" 
    />
</li>
<li>
    <api 
        name="UtilitiesAPI"
        type="import"
        category="official"
        url="@org-openide-util@/org/openide/util/doc-files/api.html"
        group="java" 
    />
</li>
<li>
    <api 
        name="NodesAPI"
        type="import"
        category="official"
        url="@org-openide-nodes@/org/openide/nodes/doc-files/api.html"
        group="java" 
    />    
</li>
<li>
    <api 
        name="ModulesAPI"
        type="import"
        category="official"
        url="@org-openide-modules@/org/openide/modules/doc-files/api.html"
        group="java" 
    />
</li>
<li>
    <api type='import' 
    group='java' 
    category='official' 
    name='org.openide.options' 
    url='@org-openide-options@/overview-summary.html'/>    
</li>            
<li>
    <api type='import' 
    group='java' 
    category='official' 
    name='org.openide.windows' 
    url='@org-openide-windows@/overview-summary.html'/>
</li>            
<li>
    <api type='import' 
    group='java' 
    category='official' 
    name='org.openide.actions' 
    url='@org-openide-actions@/overview-summary.html'/>
</li>            
</ul>
</answer>

<!--
        
     <question id="dep-non-nb">
            What other projects outside NetBeans does this one depend on?
            
            <hint>
            Some non-NetBeans projects are packaged as NetBeans modules
            (see <a href="http://libs.netbeans.org">libraries</a>) and
            it is prefered to use this approach when more modules may
            depend on such third-party library.
            </hint>
        </question>
-->
<answer id="dep-non-nb">
SAX parser.
</answer>



<!--
        
     <question id="dep-platform">
            On which platforms does your module run? Does it run in the same
            way on each?
            <hint>
            If your module is using JNI or deals with special differences of
            OSes like filesystems, etc. please describe here what they are.
            </hint>
        </question>
-->
<answer id="dep-platform">
Platform independent. 
</answer>



<!--
        
     <question id="deploy-jar">
            Do you deploy just module JAR file(s) or other files as well?
            <hint>
            If your module consist just from one module JAR file, just confirm that.
            If it uses more than one JAR, describe where there are located, how
            they refer to each other. 
            If it consist of module JAR(s) and other files, please describe
            what is their purpose, why other files are necessary. Please 
            make sure that installation/deinstallation leaves the system 
            in state as it was before installation.
            </hint>
        </question>
-->
<answer id="deploy-jar">
<code>SystemOption</code> and <code>ServiceType</code> are inside <samp>openide.jar</samp>;
But the settings infrastructure is distributed 
between <samp>openide.jar</samp> and <samp>core.jar</samp>;
Instead of <code>SystemOption</code> or <code>ServiceType</code>  can be used arbitrary object , that 
cooperate with convertor. Infrastracture for convertos is in <samp>core-settings.jar</samp>;
</answer>



<!--
        
     <question id="deploy-nbm">
            Can you deploy an NBM via the Update Center?
            <hint>
            If not why?
            </hint>
        </question>
-->
<answer id="deploy-nbm">
<samp>openide.nbm</samp> and <samp>core.nbm</samp>) are reachable via the Update Center .
</answer>



<!--
        
     <question id="deploy-packages">
            Are packages of your module made inaccessible by not declaring them
            public?
            
            <hint>
            NetBeans module system allows restriction of access rights to
            public classes of your module from other modules. This prevents
            unwanted dependencies of others on your code and should be used
            whenever possible (<a href="http://www.netbeans.org/download/apis/org/openide/doc-files/upgrade.html#3.4-public-packages">
            public packages
            </a>). 
            </hint>
        </question>
-->
<answer id="deploy-packages">
<code>SystemOption</code>  and <code>ServiceType</code> are publicly accessible.  
The settings infrastructure for <code>SystemOptions</code> resides in   <samp>core.jar</samp> 
and is considered private except <code>InstanceDataObject</code> which is in <samp>openide.jar</samp>, which
is public.  Infrastracture for convertos is in <samp>core-settings.jar</samp> exposes some  packages  explicitly declaring them in manifest, 
 which means that all other packages are  inaccessible.
</answer>



<!--
        
     <question id="deploy-shared">
            Do you need to be installed in the shared location only, or in the user directory only,
            or can your module be installed anywhere?
            <hint>
            Installation location shall not matter, if it does explain why.
            Consider also whether <code>InstalledFileLocator</code> can help.
            </hint>
        </question>
-->
<answer id="deploy-shared">
<samp>openide.jar</samp> and <samp>core.jar</samp> must be in the shared location as it is part of the core of NetBeans.
<samp>core-settings.jar.jar</samp> can be anywhere.
</answer>



<!--
        
     <question id="exec-classloader">
            Does your code create its own class loader(s)?
            <hint>
            A bit unusual. Please explain why and what for.
            </hint>
        </question>
-->
<answer id="exec-classloader">
No.
</answer>



<!--
        
     <question id="exec-component">
            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 behaviour 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">
No.
</answer>

<!--
        <question id="exec-introspection">
            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">
No answer
</answer>

<!--
        <question id="exec-process">
            Do you execute an external process from your module? How do you ensure
            that the result is the same on different platforms? Do you parse output?
            Do you depend on result code?
            <hint>
            If you feed an input, parse the output please declare that as an API.
            </hint>
        </question>
-->
<answer id="exec-process">
No external process.
</answer>

<!--
        
     <question id="exec-privateaccess">
            Are you aware of any other parts of the system calling some of 
            your methods by reflection?
            <hint>
            If so, describe the "contract" as an API. Likely private or friend one, but
            still API and consider rewrite of it.
            </hint>
        </question>
-->
<answer id="exec-privateaccess">
There are method invocations between parts of setting infrastructure.
<ul>
<li>
If there is created new persistent instance of setting object in the runtime, 
then <code>InstanceDataObject</code> that comes from <samp>openide.jar</samp>, calls 
method responsible for storing setting on disk. This method is expected to have 
following decaration <code>public void methodName (java.io.Writer w, Object inst)</code>. Which
method and from which module is invoked depends on configuration. 
</li>
<li>
If new persistent instances of setting was created, then infrastructure must be notified about it, to be able to listen
on changes and ensure , that all changes will be stored. Then from <code>InstanceDataObject</code>
is used  <code>Lookup</code> to find <code>InstanceCookie</code>. Then method <code>setInstance</code>
is invoked on instance of <code>InstanceCookie</code>. This binds instance of setting to setting infrastructure.
Which <code>Lookup</code> and then also which <code>InstanceCookie</code> is used depends again on cofiguration.
<a href="@org-netbeans-modules-settings@/org/netbeans/spi/settings/doc-files/api.html">description of  configuration</a>.
</li>
<li>
Also org.openide.util.SharedClassObject.reset is called from org.netbeans.modules.settings.convertors.XMLSettingsSupport.SettingsRecognizer.
</li>
</ul>


</answer>



<!--
        
     <question id="exec-property">
            Is execution of your code influenced by any environment or
            Java system (<code>System.getProperty</code>) property?
            
            <hint>
            If there is a property that can change the behaviour of your 
            code, somebody will likely use it. You should describe what it does 
            and the stability category of this API. You may use
            <pre>
                &lt;property name="id" category="private" &gt;
                    description of the property, where it is used, what it influence, etc.
                &lt;/property&gt;            
            </pre>
            </hint>
        </question>
-->
<answer id="exec-property">
Neither java system nor  (<code>System.getProperty</code>) property. But attributes 
attached to <code>FileObject</code> are used for configuration. This configuration is too complex
and can't be separated from entity registration and so on.  So, here is 
 <a href="@org-netbeans-modules-settings@/org/netbeans/spi/settings/doc-files/api.html#use-own">
  description of  configuration</a>.
<api name="org.openide.util.SharedClassObject.initialize" category="private" group="property" type="import">
<code>SystemOption</code> needs to know whether the <code>SharedClassObject</code>
is just performing initialization and this is done using 
<code>this.getProperty ("org.openide.util.SharedClassObject.initialize")</code> 
which returns null if initialize is not called and <code>Boolean.TRUE</code> if 
it is.
</api>
</answer>



<!--
        
     <question id="exec-reflection">
            Does your code use Java Reflection to execute other code?
            <hint>
            This usually indicates a missing or unsufficient 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">
Yes reflection is used heavily. 
<ul>
<li>
There is used reflection to create new instance of setting. Either direcltly <code>newInstance</code> or factory method, that
is defined in setting  <a href="http://www.netbeans.org/dtds/sessionsettings-1_0.dtd"> file</a>.
</li>
<li>
 Setting infrastructure registers its 
own PropertyChangeListener to know about changes and calls <code>addPropertyChangeListener </code> on 
setting instances.  There is also called pair method <code> removePropertChangeListener</code>. 
</li>
<li>
For synchronization of file name with instance name is called on setting instance method <code>getDisplayName</code> and 
<code>getName</code>.
</li>
<li>
If settings is implemented as <code>SystemOption</code>, then there is necessary to know if is project specific or global, to
be able to reset it to default value after another project was chosen. Then there is called method <code>isGlobal</code> by reflection on
instance of setting.
</li>
<li>
If <code>XMLPropertiesConvertor</code> is used for settings based on xml with grammar defined by 
<a href="http://www.netbeans.org/dtds/properties-1_0.dtd">
<code>-//NetBeans org.netbeans.modules.settings.examples//DTD XML ProxySettings 1.0//EN</code></a>, then methods
<code>readProperties</code> and <code>writeProperties</code> is used on instance of setting.
</li></ul>
</answer>



<!--
        
     <question id="format-clipboard">
            Which data flavors (if any) does your code read from or insert to
            the clipboard?
        </question>
-->
<answer id="format-clipboard">
No special implementation.
</answer>



<!--
        
     <question id="format-dnd">
            Which protocols (if any) does your code understand during Drag &amp; Drop?
        </question>
-->
<answer id="format-dnd">
No special implementation. 
</answer>



<!--
        
     <question id="format-types">
            Which file formats (if any) does your code read or write on disk?
        </question>
-->
<answer id="format-types">
<ul>
<li><api group="dtd" category="stable" type="export" name="sessionsettings-1_0.dtd" url="http://www.netbeans.org/dtds/sessionsettings-1_0.dtd"><samp>-//NetBeans//DTD Session settings 1.0//EN</samp></api></li>
<li><api group="dtd" category="devel" type="export" name="properties-1_0.dtd" url="http://www.netbeans.org/dtds/properties-1_0.dtd"><samp>-//NetBeans org.netbeans.modules.settings.examples//DTD XML ProxySettings 1.0//EN</samp></api></li>
</ul>
</answer>



<!--
        
     <question id="lookup-lookup">
            Does your module use <code>org.openide.util.Lookup</code>
            to find any components to communicate with? Which ones?
            
            <hint>
            Please describe the interfaces you are searching for, where 
            are defined, whether you are searching for just one or more of them,
            if the order is important, etc. Also clasify the stability of such
            API contract.
            </hint>
        </question>
-->
<answer id="lookup-lookup">
<ul>
<li>
In <code>InstanceDataObject.createSettingsFile</code> is looked up <code>ServiceType.Registry</code> to be sure, 
that ServiceType is unique.
</li>
<li>
Also <code>ClassLoader</code> is looked up often to find <code>ModuleManager.SystemClassLoader</code> .
</li>
<li>
Hack for system options implemented in <code>SharedClassObject.findObject</code> lookes 
for instance of setting class in the active session to find serialized state of the option, if such state exists it is deserialized before 
the object is returned from lookup, then all SystemOptions are deserialized at this place  the first time anybody asks for the option.
</li></ul>
</answer>



<!--
        
     <question id="lookup-register">
            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">
Yes. There is registered <code>Environment.Provider</code> which is ultimately
used to provide <code>Lookup</code>, that provides <code>InstanceCookie</code>. 
This is a second way how can mainly <code>InstanceDataObject</code> call
outside  implementation (first one are method calls by reflection).
</answer>



<!--
        
     <question id="lookup-remove">
            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">
No.
</answer>



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



<!--
        
     <question id="perf-huge_dialogs">
            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">
No.
</answer>



<!--
        
     <question id="perf-limit">
            Are there any hardcoded or practical limits in the number or size of
            elements your code can handle?
        </question>
-->
<answer id="perf-limit">
No.
</answer>



<!--
        
     <question id="perf-mem">
            How much memory does your component consume? Estimate
            with a relation to the number of windows, etc.
        </question>
-->
<answer id="perf-mem">
Hardly to estimate.
</answer>



<!--
        
     <question id="perf-menus">
            Does your module use dynamically updated context menus, or
            context-sensitive actions with complicated enablement logic?
        </question>
-->
<answer id="perf-menus">
No
</answer>



<!--
        
     <question id="perf-progress">
            Does your module execute any long-running tasks?
            <hint>Typically they are tasks like connecting over
            network, computing huge amount of data, compilation.
            Such communication should be done asynchronously (for example
            using <code>RequestProcessor</code>), definitively it should 
            not block AWT thread.
            </hint>
        </question>
-->
<answer id="perf-progress">
No. Perhaps if ToolsOption is showed, then createing of nodes defined 
in UI/Services may take relatively enough time, but not sure if this should be
considered as part of setting infrastructure.
</answer>



<!--
        
     <question id="perf-scale">
            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?
            Please include some estimates.
        </question>
-->
<answer id="perf-scale">
Not completely relevant questin in this case. There is not  so much important how many settings will be defined,
but how heavily will be used.
</answer>



<!--
        
     <question id="perf-startup">
            Does your module run any code on startup?
        </question>
-->
<answer id="perf-startup">
No. Instances are provided on request, the same is true for activity of infrastructure.
</answer>



<!--
        
     <question id="perf-wakeup">
            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">
No. 
</answer>



<!--
        
     <question id="resources-file">
            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 prefered
            way that should be used. But of course there can be situations when
            this is not suitable.
            </hint>
        </question>
-->
<answer id="resources-file">
No.
</answer>



<!--
        
     <question id="resources-layer">
            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></p>
Provided layers:
<ul>
<li><samp>core-settings.jar  org/netbeans/modules/settings/resources/mf-layer</samp> </li>
<li>In <samp>core.jar</samp> in org/netbeans/core/resources/mf-layer.xml</li> 
</ul>

<p></p>
Provided folderes: 
<ul>
<li><api name="RuntimeInstancesRegistry" group="layer" type="export" category="official" url="@org-netbeans-modules-settings@/org/netbeans/spi/settings/doc-files/api.html#use-memory">
<b>xml/memory</b>: Associates runtime instance with environment provider. </api><p></p></li>
<li><api name="ServicesDisplayRegistry" group="layer" type="export" category="official" url="@org-openide-util@/org/openide/util/doc-files/api.html#lookup-ui">
<b>UI/Services</b>: The root folder for displaying options. </api><p></p></li>
</ul>
</answer>



<!--
        
     <question id="resources-mask">
            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">
Yes <samp>core-settings.jar</samp> override <samp>xml/lookup/Netbeans/DTD_Session_settings_1_0.instance</samp> in 
<samp>core.jar</samp> and mainly its attributes.  So, if is <samp>core-settings.jar</samp> present, then take over functionality of settings 
infrastructure implemented in <samp>core.jar</samp>.
</answer>



<!--
        
     <question id="resources-read">
            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 clasify according to 
            <a href="http://openide.netbeans.org/tutorial/api-design.html#categories">
            common stability categories</a>.
            </hint>
        </question>
-->
<answer id="resources-read">
Many times mentioned in this document. See 
<a href="@org-netbeans-modules-settings@/org/netbeans/spi/settings/doc-files/api.html"> this document</a>.
</answer>

</api-answers>
