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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="1.23"
author="dsimonek@netbeans.org, mkleint@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.
If possible please provide
simple diagrams.
</hint>
</question>
-->
<answer id="arch-overall">
<api name="MultiView" group="java" type="export" category="stable"
url="@TOP@/overview-summary.html">
Provides support for creation of editors composed from
multiple (independent) elements. One can either specify
the <a href="@TOP@/org/netbeans/core/spi/multiview/MultiViewFactory.html">
elements directly</a>
or read them from a
<a href="@TOP@/org/netbeans/core/api/multiview/MultiViews.html">
declarative registration</a> for a particular mime type.
</api>
</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?
</hint>
</question>
-->
<answer id="arch-quality">
We are going to use standard unit tests. Unit tests should include tests of
MultiViewElement implementation method calls sequence, number of calls. Further
way tests of whole MultiViewTopComponent loading/storing, tests of proper config
xml reading.
</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">
Total time estimate is 4 months. First two months is design and implementation phase,
other two months are reserved for stabilization phase. One developers will work
on the project. Final milestones are aligned with milestones of cdp promotion D
product.
</answer>
<!--
<question id="arch-usecases" when="init">
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">
There is an introduction to MultiView and its usage in its
<a href="@TOP@/overview-summary.html">javadoc</a>. It covers the major part
of available usecases.
Here is just
a list of frequently asked or interesting questions slowly expanding as
people ask them:
<h3>MultiView faq:</h3>
<usecase id="serialization" name="How does serialization work?" >
<em><b>Q:</b>
How does serialization of multiviews work and what needs to be serializable?
</em>
<p>
First of all, you don't need to worry about serialization if all your <code>MultiViewDescription</code> instances
contained in the multiview state to be non serializable.
Meaning they all return <code>TopComponent.PERSISTENCE_NEVER</code> in <code>MultiViewDescription.getPersistenceType()</code>.
</p>
<p>
If at least one of the views requires serialization, you have no choice but to make all
<code>MultiViewDescription</code> implementors serializable.
You also can persist the MultiViewElement instances that the multiview contains. The algorithm here is a bit complicated for
performance reasons. Only those Elements are stored that were created during the session and which are Serializable.
So if the user never switches to the 4rd tab, and it's corresponding element and visual component never get created, then
it won't be stored. (We would have to create it just for the sake of persistance).
So if your visual component needs some inital context for creation, you should store it in the description instance, and if the visual component
wants to store it's state (location of cursor, selected field, something else that makes sense for the opened component) you should store it in the MultiViewElement.
So basically if you are always able create the Element from Description without any persisted data, you don't need to persist anything.
</p>
<p>
If you define your own <code>CloseOperationHandler</code> implementation for the multiview component, then you also ought to define it
Serializable. Otherwise it will be silently replaced by the default handler on restoration of the multiview component.
</p>
</usecase>
<usecase id="displayName" name="How to set the display name?" >
<em><b>Q:</b>
How do I set the display name for the multiview component?
</em>
<p>
Each <code>MultiViewDescription</code> defines display name and icon. While the icon
is meant for the whole document/view tab, the display name is just for the inner switching button.
So how does one set the name for the whole MultiView component? It can be done when creating the component.
</p>
<pre>
TopComponent mvtc = MultiViewFactory.createMultiView(myDescriptions);
mvtc.setDisplayName("My static mvtc displayName");
</pre>
<p>
Later in the lifecycle of the component, it can be also influenced from within the individual
multiview visual elements using the <code>MultiViewElementCallback.updateTitle()</code> method.
</p>
</usecase>
</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">
Multi views are general mechanism for displaying several perspectives, or views of data,
which will be used consistently across whole IDE window system. Using multi views
will enable modules to visually represent data document or object in unified manner
at one specific place in the system, yet still allowing for different perspectives
of data viewing.
</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">
The module itself doesn't expose anything brandable (at least to my knowledge.)
</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">
No.
</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">
XXX no answer for compat-version
</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">
XXX no answer for dep-jre
</answer>
<!--
<question id="dep-jrejdk" when="final">
Do you require the JDK or is the JRE enough?
</question>
-->
<answer id="dep-jrejdk">
XXX no answer for dep-jrejdk
</answer>
<!--
<question id="dep-nb" when="init">
What other NetBeans projects and modules does this one depend on?
<hint>
If you want, 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>
</hint>
</question>
-->
<answer id="dep-nb">
MultiViews project depends on Window System API, namely org.openide.windows.TopComponent
API.
It also depends on some new APIs in openide, namely NbDocument.CustomToolbar and CloneableEditorSupport.Pane
</answer>
<!--
<question id="dep-non-nb" when="init">
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 preferred to use this approach when more modules may
depend on such third-party library.
</hint>
</question>
-->
<answer id="dep-non-nb">
This project doesn't depend on any outside Netbeans projects.
</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 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">
Module MultiViews should run on all platforms IDE is able to run, no restrictions
are planned. It runs the same on all platforms expect LF code. It's expected that
look and feel code will have to be slightly different for supported OS. Chnages
are expected to be as small as possible, touching only drawing, not behaviour.
</answer>
<answer id="deploy-dependencies">
Nothing.
</answer>
<!--
<question id="deploy-jar" when="impl">
Do you deploy just module JAR file(s) or other files as well?
<hint>
If your module consists of just one module JAR file, just confirm that.
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">
Just one module jar.
</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">
Yes.
</answer>
<!--
<question id="deploy-packages" when="init">
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/javadoc/OpenAPIs/org/openide/doc-files/upgrade.html#3.4-public-packages">
public packages
</a>). If you do not restrict access to your classes you are
making it too easy for other people to misuse your implementation
details, that is why you should have good reason for not
restricting package access.
</hint>
</question>
-->
<answer id="deploy-packages">
Yes, they will be.
</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">
XXX no answer for deploy-shared
</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">
No.
</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">
XXX no answer for exec-component
</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">
Action.getClass() is called in MultiViewTopComponent on actions from the element to check for Window system
related actions, if these are found, the element itself is a topcomponent and we need to replace it's actions with the MultiViewTopComponent ones.
Otherwise the action will not be trigger on the whole MVTC.
</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">
No.
</answer>
<!--
<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">
Nothing is executed.
</answer>
<!--
<question id="exec-property" when="impl">
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 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">
<api name="multiview.toolbarVisible" category="devel" group="preferences" type="export">
<p>
The visibility of
<a href="@TOP@/org/netbeans/core/spi/multiview/MultiViewElement.html#getToolbarRepresentation--">toolbar</a>
is controlled by a preference shared with editor module.
The multiview implementation listens and uses following property:
</p>
<pre>
MimeLookup.getLookup(MimePath.EMPTY).lookup(Preferences.class).getBoolean("toolbarVisible", true);
</pre>
<p>
to find out whether all toolbars in all multiviews should be visible or not. Also,
since 1.25, the toolbar is hidden completely. There is a tab switching action
in multi view component popup menu to compensate this.
</p>
</api>
</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">
No.
</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">
All calls are expected to be made from Swing AWT event thread.
</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">
No Clipboard operations.
</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">
No DND.
</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?
</question>
-->
<answer id="format-types">
Standard topcomponent serialization is used.
</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>
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.
</hint>
</question>
-->
<answer id="lookup-lookup">
No.
</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">
No.
</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">
No.
</answer>
<!--
<question id="perf-exit" when="final">
Does your module run any code on exit?
</question>
-->
<answer id="perf-exit">
No.
</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">
No.
</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">
Yes, there are practical limits enforced in visual design. Number of different
view elements for one tab (MultiViewTopComponent) must not exceed 7 or 8,
according to the HIE.<br></br>
Data model underneath will not have such limit, will use standard java collections.
</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">
XXX no answer for perf-mem
</answer>
<!--
<question id="perf-menus" when="final">
Does your module use dynamically updated context menus, or
context-sensitive actions with complicated enablement logic?
</question>
-->
<answer id="perf-menus">
XXX no answer for perf-menus
</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">
XXX no answer for perf-progress
</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">
Perfomance of MultiViewTopComponent is influenced by performance of components
that will act as individual MultiViewElements. From what we know today that means
performance of Editor, Form Editor, Component Palette, Property Sheet, VCS Outputs,
To Do list. Also number of view elements affect performance of MultiViewTopComponent.
<br/>
The separation of MultiViewElement and MultiViewDescription interfaces is meant to allow lazy creation of not
visible components and providing them on demand. This should influence first usage performance.
</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">
MultiViewTopComponent probably should load just active MultiViewElement completely,
loading inactive view elements lazily.
Javadoc comments in MultiViewElement interface will notify developers to keep
perf-important methods fast executed.
</answer>
<!--
<question id="perf-startup" when="final">
Does your module run any code on startup?
</question>
-->
<answer id="perf-startup">
No. Except for deserialization of opened components.
</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">
No.
</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">
No.
</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">
No.
</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">
No.
</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>
<api category="devel" group="branding" name="MultiViewElement.Spliting.Enabled" type="export">
By default a MultiViewElement allows the containing TopComponent to split it.
Some systems may however find this not of any use. Then they should brand the
<code>MultiViewElement.Spliting.Enabled</code> to <code>false</code>. NetBeans IDE
by default does allow spliting.
</api>
</p>
</answer>
<!-- Copy this above the </api-answers> tag! -->
<!--
<question id="security-grant" when="final">
Does your code grant addition rights to some code?
<hint>Avoid using a classloder that adds some extra
permissions to loaded code unless realy necessary.
Also note that your API implementation
can also expose unneeded permissions to enemy code by
AccessController.doPrilileged() calls.</hint>
</question>
-->
<answer id="security-grant">
XXX no answer for security-grant
</answer>
<!--
<question id="security-policy" when="final">
Does your functionality require standard policy file modification?
<hint>Your code may pass control to third party code not
coming from trusted domain. It covers code downloaded over
network or code coming from libraries that are not bundled
with NetBeans. Which permissions it needs to grant to which domain?</hint>
</question>
-->
<answer id="security-policy">
XXX no answer for security-policy
</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>
XXX no answer for exec-ant-tasks
</p>
</answer>
</api-answers>