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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="1.29"
  author="tor@netbeans.org"
>

  &api-questions;


<!--
        <question id="arch-overall" when="init">
            Describe the overall architecture. 
            <hint>
            What will be API for 
            <a href="http://openide.netbeans.org/tutorial/api-design.html#design.apiandspi">
                clients and what support API</a>? 
            What parts will be pluggable?
            How will plug-ins be registered? Please use <code>&lt;api type="export"/&gt;</code>
            to describe your general APIs and specify their
            <a href="http://openide.netbeans.org/tutorial/api-design.html#category-private">
            stability categories</a>.
            If possible please provide simple diagrams.
            </hint>
        </question>
-->
    <answer id="arch-overall">
        <p>
      GSF is a set of APIs to make it easier to provide editing support for new languages.
      The goal is to make it as easy as possible to write first-rate support, such that
      language developers can focus only on aspects of their language, not on infrastructure
      tasks.  Language plugin developers don't write editor actions, event listeners, and so on.
      Instead, they implement their own lexers, parsers, and narrow feature APIs where they
      use their own lexer token sequences and parse trees to implement the language-specific
      aspects of features like code completion, go to declaration, semantic highlighting and so on.
        </p>
        <p>
            GSF can be seen as a layer on top of some of the existing NetBeans editing APIs.
            It directly uses the Lexer API, and while it has its own parsing API, the plan
            is to replace that with the upcoming NetBeans Parsing API.  It defines a number
            of additional feature APIs, such as "keystroke handler", and "code completion handler",
            which lets modules go and implement for example logic that should be run when
            the user presses Return, without the need to go in and implement a custom
            data loader, editor kit, default editing actions, and so on.
        </p>
        <p>
            Here's an illustration of this:
            <br/>
            <br/>
            <img class="inline" src="@TOP@/gsf-architecture.png" alt="Diagram showing GSF's architecture" />
            <br/>
            <br/>
            The language plugins shown above (Ruby, Groovy, etc.) are the targets of the
            GSF API.   GSF provides interfaces (and in many cases, optional default
            abstract class implementations) that the language plugins implement and
            register. These implementations are then invoked as part of feature
            implementations provided by GSF. All the generic work and UI involved
            in writing various language features are handled by GSF, and it delegates
            to language plugins for the actual language-specific logic.
        </p>
        <p>
            The key thing here is that the GSF implementation provides implementations for
            a lot of the non-language-specific code that is currently required to implement
            language features. For example, semantic highlighting involves writing an
            editing highlighting layer, scheduling parsing jobs when the editor is
            modified, and iterating the parse tree to pull out interesting information,
            and then mapping this to the editing highlighting layer.  Only the parse
            tree analysis part here is specific per language, so GSF handles all the
            other aspects and simply delegates to the language plugin for this
            specific part.
        </p>
        <p>
            Here's another example of this, for the Instant Rename feature:
            <br/>
            <br/>
            <img class="inline" src="@TOP@/instant-rename.png" alt="Diagram showing instant rename operation" />
            <br/>
            <br/>
            This diagram shows the division of labor, with GSF on the left hand side
            and the language plugin on the right. The parser task handled by the language
            plugin is reused for nearly all features. The language plugin implements
            a lexer, an optional parser, and an optional indexer, and these are then
            invoked as necessary before asking the language plugin to provide answers
            for specific features like go to declaration, code completion, and so on.
        </p>
        <p>
            Language plugins register their services via the default file system layer.
            This is described in more detail in the
            <a href="@TOP@/registration.html">Registration Document</a>.
            NOTE - many details of registration are still TBD. There
            are some significant implementation problems with the current approach
            and I'd really like to find a better way to do it.
        </p>
    </answer>


<!--
        <question id="arch-quality" when="init">
            How will the <a href="http://www.netbeans.org/community/guidelines/q-evangelism.html">quality</a>
            of your code be tested and 
            how are future regressions going to be prevented?
            <hint>
            What kind of testing do
            you want to use? How much functionality, in which areas,
            should be covered by the tests? How you find out that your
            project was successful?
            </hint>
        </question>
-->
    <answer id="arch-quality">
<p>
    Unit tests.  GSF needs more. GSF provides unit testing support for its clients,
    which makes it really trivial to test that your (say) code completion handler
    works correctly. You just subclass GSF's <code>TestCase</code> implementation (which in
    turn is a subclass of <code>NbTestCase</code>), and then there are a number
    of feature specific assertion methods you can call. To test your semantic highlighter,
    or your keystroke handler, or your code completion handler, you typically just
    have to write a single line, such as "checkCompletion", and hand it a test file
    and a caret location, and GSF handles calling your parser, calling your
    feature handler, golden file generation and diffing, etc.
</p>
<p>
    This is call described in more detail in the <a href="@TOP@/unit-testing.html">unit testing document</a>.
</p>
<p>
    However, GSF <b>itself</b> needs more testing. GSF is all about infrastructure,
    and UI, so it's much trickier to test. I've been relying on a lot of manual testing
    at this point; e.g. unit tests cover Ruby and JavaScript's correct result computation
    of say code completion data, and I've manually tested that these code completion
    results show correctly on the screen.
</p>
<p>
    I'd really like to get some help in writing infrastructure tests to ensure
    that all of this is correct.
</p>
    </answer>


<!--
        <question id="arch-time" when="init">
            What are the time estimates of the work?
            <hint>
            Please express your estimates of how long the design, implementation,
            stabilization are likely to last. How many people will be needed to
            implement this and what is the expected milestone by which the work should be 
            ready?
            </hint>
        </question>
-->
    <answer id="arch-time">
<p>
    There are a lot of unknown factors involved here; fixing GSF registration, adapting
    to the Parsing API (which will require a number of API and implementation changes),
    as well as competing resources for the Ruby and JavaScript editor maintenance as well
    as consulting on other language support projects like the Python one. 
</p>
<p>
    However, an educated guess would be something along the order of six months.
</p>
    </answer>


<!--
        <question id="arch-usecases" when="init">
            <hint>
                Content of this answer will be displayed as part of page at
                http://www.netbeans.org/download/dev/javadoc/usecases.html 
                You can use tags &lt;usecase name="name&gt; regular html description &lt;/usecase&gt;
                and if you want to use an URL you can prefix if with @TOP@ to begin
                at the root of your javadoc
            </hint>
        
            Describe the main <a href="http://openide.netbeans.org/tutorial/api-design.html#usecase">
            use cases</a> of the new API. Who will use it under
            what circumstances? What kind of code would typically need to be written
            to use the module?
        </question>
-->
    <answer id="arch-usecases">
        <p>
   XXX no answer for arch-usecases
        </p>
    </answer>


<!--
        <question id="arch-what" when="init">
            What is this project good for?
            <hint>
            Please provide here a few lines describing the project, 
            what problem it should solve, provide links to documentation, 
            specifications, etc.
            </hint>
        </question>
-->
    <answer id="arch-what">
        <p>
GSF attempts to make adding deep editing support for new languages in NetBeans as easy as
possible, attempting to reuse existing lexers and parsers, and making it possible to
add advanced features like quickfixes, code completion, semantic highlighting, and so on.
GSF also attempts to let language plugin developers focus <b>only</b> on the language
specific aspects of the editing support. GSF handles infrastructure tasks like
parser scheduling, editor kit, loader and action implementations, UI, and so on.
As a language plugin developer, "all" you have to do is implement (usually via
delegation) your own lexer, parser, indexer, and then implement thin feature APIs
like a keystroke handler, a code completion handler, a declaration finder, and so on,
based on your own lexing, parser, and indexed data.
        </p>
        <p>
There is a lot of additional documentation for GSF in its
<a href="@TOP@/overview-summary.html">overview document</a>.
            </p>
    </answer>


<!--
        <question id="arch-where" when="impl">
            Where one can find sources for your module?
            <hint>
                Please provide link to the Hg web client at
                http://hg.netbeans.org/
                or just use tag defaultanswer generate='here'
            </hint>
        </question>
-->
    <answer id="arch-where">
        <defaultanswer generate='here' />
    </answer>


<!--
        <question id="compat-deprecation" when="init">
            How the introduction of your project influences functionality
            provided by previous version of the product?
            <hint>
            If you are planning to deprecate/remove/change any existing APIs,
            list them here accompanied with the reason explaining why you
            are doing so.
            </hint>
        </question>
-->
    <answer id="compat-deprecation">
        <p>
            GSF will not deprecate any existing APIs, but it provides a much
            simpler way to implement functionality that is covered by other
            APIs.  Instead of implementing your own DataLoader, DataObject,
            EditorKit, various editor actions etc., you can simply reuse
            GSF's default implementations of these, which will delegate to
            your plugin only for the language-specific aspects.
        </p>
        <p>
            In some cases, not all the functionality in the existing APIs are
            exposed through GSF, so there may be cases where developers want
            to register with the base editing API instead of the GSF layer
            on top.
        </p>
    </answer>


<!--
        <question id="compat-i18n" when="impl">
            Is your module correctly internationalized?
            <hint>
            Correct internationalization means that it obeys instructions 
            at <a href="http://www.netbeans.org/download/dev/javadoc/org-openide-modules/org/openide/modules/doc-files/i18n-branding.html">
            NetBeans I18N pages</a>.
            </hint>
        </question>
-->
    <answer id="compat-i18n">
        <p>
            Yes, GSF is properly i18n'ized. Any exceptions are unintentional bugs.
        </p>
    </answer>


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


<!--
        <question id="compat-version" when="impl">
            Can your module coexist with earlier and future
            versions of itself? 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">
<p>
GSF was included in 6.0 (as part of the Ruby cluster), and in 6.1 (as part of the GSF
cluster used by JavaScript, HTML and Ruby), and probably in 6.5. In each version,
GSF has changed incompatibly. 
</p>
<p>
    GSF doesn't have any settings that need to be preserved compatibly (that I can
    think of).  There is a tricky area around editor kit settings (for things like
    indentation size, tab versus space selection, etc). For architectural reasons,
    this has been a problem for GSF, where a single EditorKit is shared by multiple
    mime types, which isn't compatible with the old BaseOptions approach (where
    each mimetype needed its own editor kit). This is being addressed in NetBeans 6.5
    and will hopefully not be an issue in the future.
</p>
<p>
    One area of concern is the way GSF registers editing services. In order to
    implement various editing (and navigation and tasklist) functionality, it needs
    to expose its implementations of various services to other modules that are
    doing system file system lookup. It does this by actually writing into the system
    file system at startup. This is persisted in the user directory, under
    <code>config/Editors/<i>mimetype</i></code>. This hardcodes in for example
    the full package and class name of the implementation classes for GSF. I have
    dealt with this in the past by having various logic in my code go and look
    for old registration files and removing them. And furthermore, the settings migration
    wizard for 6.1 had specific rules to block these files.
</p>
<p>
    This mechanism (registering services with the editor, navigation api and
    tasklist api) is one I'd <b>really</b> like to improve. I had hoped to 
    use the pluggable system file system (see 
    <a href="http://ruby.netbeans.org/issues/show_bug.cgi?id=26338">issue 26338</a>),
    but I couldn't get it to work. Hopefully the GSF inception review will 
    come up with some advise for this area.
</p>
    </answer>


<!--
        <question id="dep-jre" when="final">
            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">
        <p>
I'm using JRE 5.0+ features and APIs.
        </p>
    </answer>


<!--
        <question id="dep-jrejdk" when="final">
            Do you require the JDK or is the JRE enough?
        </question>
-->
    <answer id="dep-jrejdk">
        <p>
I believe the JRE is enough but I haven't tested this.
        </p>
    </answer>


<!--
        <question id="dep-nb" when="init">
            What other NetBeans projects and modules does this one depend on?
            <hint>
            Depending on other NetBeans projects influnces the ability of
            users of your work to customize their own branded version of
            NetBeans by enabling and disabling some modules. Too
            much dependencies restrict this kind of customization. If that
            is your case, then you may want to split your functionality into
            pieces of autoload, eager and regular modules which can be
            enabled independently. Usually the answer to this question
            is generated from your <code>project.xml</code> file, but
            if it is not guessed correctly, you can suppress it by
            specifying &lt;defaultanswer generate="none"/&gt; and
            write here your own. Please describe such projects as imported APIs using
            the <code>&lt;api name="identification" type="import or export" category="stable" url="where is the description" /&gt;</code>.
            By doing this information gets listed in the summary page of your
            javadoc.
            </hint>
        </question>
-->
    <answer id="dep-nb">
        <defaultanswer generate='here' />
    </answer>


<!--
        <question id="dep-non-nb" when="init">
            What other projects outside NetBeans does this one depend on?
            
            <hint>
            Depending on 3rd party libraries is always problematic,
            especially if they are not open source, as that complicates
            the licensing scheme of NetBeans. Please enumerate your
            external dependencies here, so it is correctly understood since
            the begining what are the legal implications of your project.
            Also please note that
            some non-NetBeans projects are packaged as NetBeans modules
            (see <a href="http://libs.netbeans.org/">libraries</a>) and
            it is preferred to use this approach when more modules may
            depend and share such third-party libraries.
            </hint>
        </question>
-->
    <answer id="dep-non-nb">
        <p>
None.
        </p>
    </answer>


<!--
        <question id="dep-platform" when="init">
            On which platforms does your module run? Does it run in the same
            way on each?
            <hint>
            If you plan any dependency on OS or any usage of native code,
            please describe why you are doing so and describe how you envision
            to enforce the portability of your code.
            Please note that there is a support for <a href="http://www.netbeans.org/download/dev/javadoc/org-openide-modules/org/openide/modules/doc-files/api.html#how-os-specific">OS conditionally
            enabled modules</a> which together with autoload/eager modules
            can allow you to enable to provide the best OS aware support
            on certain OSes while providing compatibility bridge on the not
            supported ones.
            Also please list the supported
            OSes/HW platforms and mentioned the lovest version of JDK required
            for your project to run on. Also state whether JRE is enough or
            you really need JDK.
            </hint>
        </question>
-->
    <answer id="dep-platform">
        <p>
GSF should work on all platforms and all versions of Java, for JDK 5.0 and higher.
        </p>
        <p>
There is only one OS-specific item in GSF: The code which chooses the delay for 
parse jobs defaults to 2 seconds on Windows and 1 second elsewhere. I'm not
sure why this was done; this is code copied from Retouche (and is still there
in the <code>java.source RepositoryUpdater.java</code> file.)
        </p>
    </answer>


<!--
        <question id="deploy-dependencies" when="final">
            What do other modules need to do to declare a dependency on this one,
            in addition to or instead of the normal module dependency declaration
            (e.g. tokens to require)?
            <hint>
                Provide a sample of the actual lines you would add to a module manifest
                to declare a dependency, for example OpenIDE-Module-Requires: some.token.
                If other modules should not depend on this module, or should just use a
                simple regular module dependency, you can just answer "nothing". If you
                intentionally expose a semistable API to clients using implementation
                dependencies, you should mention that here (but there is no need to give
                an example of usage).
            </hint>
        </question>
-->
    <answer id="deploy-dependencies">
        <p>
None.
        </p>
    </answer>


<!--
        <question id="deploy-jar" when="impl">
            Do you deploy just module JAR file(s) or other files as well?
            <hint>
            Usually a module consist of one JAR file (perhaps with Class-Path
            extensions) and also a configuration file that enables it. If you
            have any other files, use
            &lt;api group="java.io.File" name="yourname" type="export" category="friend"&gt;...&lt;/api&gt;
            to define the location, name and stability of your files (of course
            changing "yourname" and "friend" to suit your needs).
            
            If it uses more than one JAR, describe where they 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/uninstallation leaves the system 
            in state as it was before installation.
            </hint>
        </question>
-->
    <answer id="deploy-jar">
        <p>
            GSF does not have any extra files or jars.
        </p>
    </answer>


<!--
        <question id="deploy-nbm" when="impl">
            Can you deploy an NBM via the Update Center?
            <hint>
            If not why?
            </hint>
        </question>
-->
    <answer id="deploy-nbm">
        <p>
        Yes
        </p>
    </answer>


<!--
        <question id="deploy-packages" when="init">
            Are packages of your module made inaccessible by not declaring them
            public?
            
            <hint>
            By default NetBeans build harness treats all packages are private.
            If you export some of them - either as public or friend packages,
            you should have a reason. If the reason is described elsewhere
            in this document, you can ignore this question.
            </hint>
        </question>
-->
    <answer id="deploy-packages">
        <p>
            Yes. The API packages in the <code>gsf.api</code> module
            will be exposed as public (they are currently
            friend only until GSF is API reviewed and approved). 
            The implementation classes in the <code>gsf</code> module
            will not be made public.
        </p>
    </answer>


<!--
        <question id="deploy-shared" when="final">
            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">
        <p>
            GSF can be installed anywhere.
        </p>
    </answer>


<!--
        <question id="exec-ant-tasks" when="impl">
            Do you define or register any ant tasks that other can use?
            
            <hint>
            If you provide an ant task that users can use, you need to be very
            careful about its syntax and behaviour, as it most likely forms an
	          API for end users and as there is a lot of end users, their reaction
            when such API gets broken can be pretty strong.
            </hint>
        </question>
-->
    <answer id="exec-ant-tasks">
        <p>
            No
        </p>
    </answer>


<!--
        <question id="exec-classloader" when="impl">
            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">
        <p>
            No
        </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">
        <p>
            No
        </p>
    </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>
No
        </p>
    </answer>


<!--
        <question id="exec-privateaccess" when="final">
            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">
        <p>
No
        </p>
    </answer>


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        <question id="exec-process" when="impl">
            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">
        <p>
No
        </p>
    </answer>


<!--
        <question id="exec-property" when="impl">
            Is execution of your code influenced by any environment or
            Java system (<code>System.getProperty</code>) property?
            On a similar note, is there something interesting that you
            pass to <code>java.util.logging.Logger</code>? Or do you observe
            what others log?
            <hint>
            If there is a property that can change the behavior of your 
            code, somebody will likely use it. You should describe what it does 
            and the <a href="http://openide.netbeans.org/tutorial/api-design.html#life">stability category</a>
            of this API. You may use
            <pre>
                &lt;api type="export" group="property" name="id" category="private" url="http://..."&gt;
                    description of the property, where it is used, what it influence, etc.
                &lt;/api&gt;            
            </pre>
            </hint>
        </question>
-->
    <answer id="exec-property">
<table border="1">
<tr>
    <th>Property</th><th>Default</th><th>Purpose</th>
</tr>
<tr>
    <td>no-ruby-camel-case-style-navigation</td><td>false</td><td>Ability to turn off camel case navigation.</td>
</tr>
<tr>
    <td>org.netbeans.javacore.ignoreDirectories</td><td>SCCS CVS .svn</td><td>Directories to skip during indexing. Copied from Retouche.</td>
</tr>
<tr>
    <td>org.netbeans.modules.gsf.enableMBeans</td><td>false</td><td>Turn on to enable MBeans to introspect memory usage and settings etc.</td>
</tr>
<tr>
    <td>gsf.im_feeling_lucky</td><td>false</td><td>Tell the Go To Declaration code to skip ambiguous results popup and just jump to first match</td>
</tr>
<tr>
    <td>LuceneIndex.debugIndexMerge</td><td>false</td><td>Enable Lucene index merging debugging. Not sure what this is for (copied code).</td>
</tr>
<tr>
    <td>gsf.preindexing</td><td>false</td><td>Tell GSF it's running as part of pre-indexing. This is used to compute indexes for libraries in advance for startup speedup. 
        Used as part of various scripts in the Ruby support which also look at this flag.</td>
</tr>
<tr>
    <td>netbeans.javacore.noscan</td><td>false</td><td>Turn off file system scanning. Inherited from Java support.</td>
</tr>
<tr>
    <td>perf.refactoring.test</td><td>false</td><td>Set by performance tests?</td>
</tr>
<tr>
    <td>org.netbeans.napi.gsfret.source.Source.reportSlowTasks</td><td>false</td><td>If set, times source tasks and reports tasks that take more than 250 ms</td>
</tr>
</table>
    </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>
There is one instance of this, inherited from Retouche, where the code is using
<code>Class.forName</code> to get access to some code which is hidden from the API.
The class is called <code>SourceAccessor</code> and it provides access to the <code>Source</code> class.
        </p>
    </answer>


<!--
        <question id="exec-threading" when="init">
            What threading models, if any, does your module adhere to? How the
            project behaves with respect to threading?
            <hint>
                Is your API threadsafe? Can it be accessed from any threads or
                just from some dedicated ones? Any special relation to AWT and
                its Event Dispatch thread? Also
                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>
Most GSF code isn't interesting from a threading perspective, but there is one exception:
The <code>Source</code> and <code>RepositoryUpdater</code> classes. These correspond to
the <code>JavaSource</code> and <code>RepositoryUpdater</code> classes in the Java Source
module, and they perform task schedling etc. in very carefully crafted multi threaded code.
I plan to replace this code with the Parsing API, which should make this all go away.
        </p>
    </answer>


<!--
        <question id="format-clipboard" when="impl">
            Which data flavors (if any) does your code read from or insert to
            the clipboard (by access to clipboard on means calling methods on <code>java.awt.datatransfer.Transferable</code>?
            
            <hint>
            Often Node's deal with clipboard by usage of <code>Node.clipboardCopy, Node.clipboardCut and Node.pasteTypes</code>.
            Check your code for overriding these methods.
            </hint>
        </question>
-->
    <answer id="format-clipboard">
        <p>
            None. 
            </p>
            <p>
                In the future, I'd like to automatically supply an HTML transferable when the
                user copies text in the editor, such that the clipboard contains a fully syntax 
                highlighted (including semantic colors) copy of the code they can paste
                into for example open office or a mail program. It would be even better if 
                this could be done in the editor itself without language plugin support,
                but if it will require specific EditorKit support, GSF will have it.
        </p>
    </answer>


<!--
        <question id="format-dnd" when="impl">
            Which protocols (if any) does your code understand during Drag &amp; Drop?
            <hint>
            Often Node's deal with clipboard by usage of <code>Node.drag, Node.getDropType</code>. 
            Check your code for overriding these methods. Btw. if they are not overridden, they
            by default delegate to <code>Node.clipboardCopy, Node.clipboardCut and Node.pasteTypes</code>.
            </hint>
        </question>
-->
    <answer id="format-dnd">
        <p>
            None.
        </p>
    </answer>


<!--
        <question id="format-types" when="impl">
            Which protocols and file formats (if any) does your module read or write on disk,
            or transmit or receive over the network? Do you generate an ant build script?
            Can it be edited and modified? 
            
            <hint>
            <p>
            Files can be read and written by other programs, modules and users. If they influence
            your behaviour, make sure you either document the format or claim that it is a private
            api (using the &lt;api&gt; tag). 
            </p>
            
            <p>
            If you generate an ant build file, this is very likely going to be seen by end users and
            they will be attempted to edit it. You should be ready for that and provide here a link
            to documentation that you have for such purposes and also describe how you are going to
            understand such files during next release, when you (very likely) slightly change the 
            format.
            </p>
            </hint>
        </question>
-->
    <answer id="format-types">
        <p>
            The only persistence GSF is involved with is the Lucene index it creates for each
            language that wants indexing and querying services. In this case, it creates
            a separate Lucene index for each combination of a language and a source or library
            root. These are all located under <code>var/cache/gsf-index</code>. This is similar
            to the Java Source module, except in GSF's case there is an extra directory
            per language such that languages have their own unique and isolated Lucene index.
            Each Lucene database is also indexed by two version numbers: one supplied by
            GSF, which is incremented when GSF changes the Lucene data format (for example
            by upgrading to a new version of GSF) and another supplied by each language
            (when they change their stored data incompatibly).
            For example, in my user dir I see these directories:
            </p>
<pre>
var/cache/gsf-index/1.118/php/0.4.2/
var/cache/gsf-index/1.118/ruby/6.103/
var/cache/gsf-index/1.118/scala/6.118/
</pre>
<p>
Here, <code>1.118</code> is the current GSF data format version, and
<code>0.4.2</code> is the current version of the data supplied by PHP, 
<code>6.103</code> by the Ruby plugin, and so on.
        </p>
    </answer>


<!--
        <question id="lookup-lookup" when="init">
            Does your module use <code>org.openide.util.Lookup</code>
            or any similar technology to find any components to communicate with? Which ones?
            
            <hint>
            NetBeans is build around a generic registry of services called
            lookup. It is preferable to use it for registration and discovery
            if possible. See
            <a href="http://www.netbeans.org/download/dev/javadoc/org-openide-util/org/openide/util/lookup/doc-files/index.html">
            The Solution to Comunication Between Components
            </a>. If you do not plan to use lookup and insist usage
            of other solution, then please describe why it is not working for
            you.
            <br/>
            When filling the final version of your arch document, 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 classify the stability of such
            API contract. Use &lt;api group=&amp;lookup&amp; /&gt; tag, so
            your information gets listed in the summary page of your javadoc.
            </hint>
        </question>
-->
    <answer id="lookup-lookup">
        <p>
            GSF uses lookup to communicate between the API module and the implementation
            module.  For example, the GSF API interfaces            
<code>org.netbeans.modules.gsf.api.EditRegions</code>,
<code>org.netbeans.modules.gsf.api.EditorOptionsFactory</code>,
<code>org.netbeans.modules.gsf.api.HintsProvider$Factory</code>,
and <code>org.netbeans.modules.gsf.api.SourceModelFactory</code>
are provided in the GSF API and implemented by the GSF module. The
<code>org.netbeans.modules.gsf.api.TypeSearcher</code> interface can be implemented
by language clients and is looked up by GSF.
</p>
    </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>
            Yes. GSF provides implementations for a wide variety of editing APIs as well
            as the tasklist and navigation APIs.

     <api group="lookup" name="org.openide.loaders.CreateFromTemplateAttributesProvider" type="export" category="official">
       Attributes provider is registered in <code>META-INF/services</code>. It provides
       <code>package</code> attribute for java templates using scripting support.
     </api>


        </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>
            None
        </p>
    </answer>


<!--
        <question id="perf-exit" when="final">
            Does your module run any code on exit?
        </question>
-->
    <answer id="perf-exit">
        <p>
            Yes. On <code>ModuleInstall.closing()</code>, the module closes the open Lucene indices,
            unregisters file system listeners and cancels scheduled parsing jobs.
        </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>
            Define "large number" please :)   There aren't many dialogs in GSF,
            but GSF does provide an Options panel for quickfixes (for language
            clients that request it, currently only Ruby), which will add
            a checkbox for every available hint.
        </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?
            <hint>
                Most of algorithms have increasing memory and speed complexity
                with respect to size of data they operate on. What is the critical
                part of your project that can be seen as a bottleneck with
                respect to speed or required memory? What are the practical
                sizes of data you tested your project with? What is your estimate
                of potential size of data that would cause visible performance
                problems? Is there some kind of check to detect such situation
                and prevent "hard" crashes - for example the CloneableEditorSupport
                checks for size of a file to be opened in editor
                and if it is larger than 1Mb it shows a dialog giving the
                user the right to decide - e.g. to cancel or commit suicide.
            </hint>
        </question>
-->
    <answer id="perf-limit">
        <p>
            None that I can think of.
            </p>
            <p>
                There may be performance problems supporting really huge
                source files. There was a bug with huge HTML files in the navigator,
                where GSF's code which expands all nodes caused some problems. 
                when there are thousands and thousands of nested elements.
                
        </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>
            GSF itself shouldn't need to hold much memory. Typically, the memory
            consumption will come from GSF's language clients, which will create
            lexing hierarchies and parsing trees which may require a fair bit of space.
        </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>
            GSF adds some actions to editor context menus which are enabled/disabled on the fly.
            There aren't many of these.
        </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>
            Yes, GSF runs parsing tasks which can often take a while. The most visible
            such task is the startup indexing task, which iterates over all the source
            folders in the user's project, checks each timestamp to see if the file
            has changed since last indexing operation, and if not, indexes the file.
        </p>
        <p>
            This should all be occurring in proper background threads.
        </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>
            The performance of GSF typically depends on the size of the
            source file, and the speed of the lexer and parser for each
            language (which is supplied by the language plugins). For example,
            most bottlenecks I've seen in Ruby development have come from
            JRuby parsing. Another slow operation I've seen is type analysis,
            which is performed by the JavaScript language plugin. GSF itself
            shouldn't cause performance problems.
        </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>
            GSF doesn't do this. Arguably, it should. There is a flag (documented
            in the properties section) which when set will complain about long
            running parsing tasks.
        </p>
    </answer>


<!--
        <question id="perf-startup" when="final">
            Does your module run any code on startup?
        </question>
-->
    <answer id="perf-startup">
        <p>
Yes. It initializes the parsing task scheduler (called RepositoryUpdater) which
will listen for project opening events, kick off background indexing tasks, etc.
        </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>
Yes. The startup indexing code is (like the Java Source module) using the 
java.io.File API to quickly scan files during startup to look for files
that should be indexed. This was deliberately using java.io.File in the Java
module for performance reasons, and I'm doing the same thing for GSF.
Once a file is identified as a source file to be indexed, it will have its
FileObject looked up and the parser proceeds from there.
        </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>
Yes, GSF writes entries into the layer on behalf of all the language clients which registers
GSF implementations that provide implementations for Editor APIs, Navigation APIs, Tasklist APIs, etc.
        </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-preferences" when="final">
            Does your module uses preferences via Preferences API? Does your module use NbPreferences or
            or regular JDK Preferences ? Does it read, write or both ? 
            Does it share preferences with other modules ? If so, then why ?
            <hint>
                You may use
                    &lt;api type="export" group="preferences"
                    name="preference node name" category="private"&gt;
                    description of individual keys, where it is used, what it
                    influences, whether the module reads/write it, etc.
                    &lt;/api&gt;
                Due to XML ID restrictions, rather than /org/netbeans/modules/foo give the "name" as org.netbeans.modules.foo.
                Note that if you use NbPreferences this name will then be the same as the code name base of the module.
            </hint>
        </question>
-->
    <answer id="resources-preferences">
        <p>
Yes. The GSF hints implementation uses the Preferences API to store persistent state for
hints that should be enabled/disabled.   When a GSF quickfix offers a solution, it also
adds a fix named something like "Disable this hint", and if you select that, the Preferences API
will be called to turn off that hint. This setting is consulted by the hints infrastructure
as well as the options UI code in GSF.
        </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
        </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
        </p>
    </answer>
</api-answers>