NetBeans Architecture Answers for Component Palette module

General Information

Question (arch-what): What is this project good for?
Answer:

The project implements a new component palette that will be reused by other projects. The new palette should provide a common look and feel for Form editor, Mobility, J2EE and possible other modules as well. UI draft specification is available here.

Question (arch-overall): Describe the overall architecture.
Answer:

The API provides access to the common component palette. The palette clients can use this API to define content to be displayed in the common palette TopComponent when their editors are active. The module will autoload. At the moment (June 10th 2005) Java API and SPi are specified in JavaDoc in the Form editor module. See packages org.netbeans.modules.palette.api and org.netbeans.modules.palette.spi in CVS branch 'palette_58859'.

Question (arch-usecases): Describe the main use cases 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?
Answer:

Basic usage

The following steps must be taken if an editor module wants to display a palette of items that can be dropped to editor window:

• Define palette's root folder in editor's layer and also define subfolders for categories and file objects for palette items.
  Another option is to create a hierarchy of Nodes (root - categories - items).
• Extend PaletteActions class that provides custom Actions for palette's popup menus.
• Use PaletteFactory to create an instance of PaletteController. The editor module keeps a reference to this object and registers a PropertyChangeListner to it to be notified of palette's selection changes.
• Add the instance of PaletteController to the lookup of editor's TopComponent.

When an item is selected in the palette and user clicks into the editor window then the module can ask for selected item by calling PaletteController.getSelectedItem(). This method returns a Lookup that holds object(s) representing the selected item. After the item is inserted into the editor window the module may clear palette's selection (ProgressController.clearSelection()) or leave the item selected to implement 'multi drop' insertion scenario.

Filtering

It is possible to filter palette content and hide some categories and/or items from the user by implementing PaletteFilter interface. Calling PaletteController.setPaletteFilter() updates palette content and repaints the palette window.

Default Settings

The initial state of the palette can be overridden by setting appropriate attributes to palette model. The list of supported attributes is defined in PaletteController class. If the palette model is create from Nodes then the attributes are extracted by calling Node.getValue() method on the root Node and category and item nodes. If the palette model is defined as folders and files in the layer then the attributes are extracted by calling FileObject.getAttribute().

Question (arch-time): What are the time estimates of the work?
Answer:

The remaining work is about 2 man/weeks (July 8th 2005).

Question (arch-quality): How will the quality of your code be tested and how are future regressions going to be prevented?
Answer:

There will be unit tests for Palette's model implementation and assertions will be used where appropriate.

Project and platform dependencies

Question (dep-nb): What other NetBeans projects and modules does this one depend on?
Answer:

OpenAPIs -

For acces to Nodes, winsys TopComponent, lookups, resource bundles etc.

Question (dep-non-nb): What other projects outside NetBeans does this one depend on?
Answer:

None

Question (dep-platform): On which platforms does your module run? Does it run in the same way on each?
Answer:

No platform dependencies.

Question (dep-jre): Which version of JRE do you need (1.2, 1.3, 1.4, etc.)?
Answer:

1.4 or greater

Question (dep-jrejdk): Do you require the JDK or is the JRE enough?
Answer:

JRE should be enough.

Deployment

Question (deploy-jar): Do you deploy just module JAR file(s) or other files as well?
Answer:

Just the module jar file: org-netbeans-modules-palette.jar

Question (deploy-nbm): Can you deploy an NBM via the Update Center?
Answer:

Yes

Question (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?
Answer:

Install location should not matter.

Question (deploy-packages): Are packages of your module made inaccessible by not declaring them public?
Answer:

Yes, non-API packages are not declared public.

Question (deploy-dependencies): What do other modules need to do to declare a dependency on this one?
Answer:

OpenIDE-Module-Module-Dependencies org.netbeans.modules.palette.api/1 > 1.0

Compatibility with environment

Question (compat-i18n): Is your module correctly internationalized?
Answer:

Yes (any uninternationalized text will be fixed during implementation).

Question (compat-standards): Does the module implement or define any standards? Is the implementation exact or does it deviate somehow?
Answer:

The palette's user inteface should match the look and feel of comparable components in competitive IDEs as defined in the UI specification document.

Question (compat-version): 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?
Answer:

API should be backwards compatible, old settings can be ignored if needed. All user settings are stored in an XML file that can be easily extended.

Access to resources

Question (resources-file): Does your module use java.io.File directly?
Answer:

No

Question (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?
Answer:

Yes, it creates folder PaletteSettings where a file is created for user settings for each palette model.
There's also Window System definition of palette's TopComponent group and mode.
Palette clients (editor modules) may define palette contents in their layers.

Question (resources-read): Does your module read any resources from layers? For what purpose?
Answer:

The default palette model is based on Nodes that may be defined in layer hierarchy.

Question (resources-mask): Does your module mask/hide/override any resources provided by other modules in their layers?
Answer:

No

Lookup of components

Question (lookup-lookup): Does your module use org.openide.util.Lookup or any similar technology to find any components to communicate with? Which ones?
Answer:

activated_node -

Palette listens to system activated node changes. The palette TopComponent opens when an editor TopComponent with a PaletteController instance in its Lookup is opened or activated. Palette window closes when the editor window is closed or deactivated and no other visible editor window supports the palette.
The palette window always shows the content from the last active editor window regardless where the input focus is. The palette content is updated when user activates a different editor window that supports the palette.

Question (lookup-register): Do you register anything into lookup for other code to find?
Answer:

No

Question (lookup-remove): Do you remove entries of other modules from lookup?
Answer:

No

Execution Environment

Question (exec-property): Is execution of your code influenced by any environment or Java system (System.getProperty) property?
Answer:

No

Question (exec-component): Is execution of your code influenced by any (string) property of any of your components?
Answer:

No

Question (exec-ant-tasks): Do you define or register any ant tasks that other can use?
Answer:

No

Question (exec-classloader): Does your code create its own class loader(s)?
Answer:

No

Question (exec-reflection): Does your code use Java Reflection to execute other code?
Answer:

No

Question (exec-privateaccess): Are you aware of any other parts of the system calling some of your methods by reflection?
Answer:

No

Question (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?
Answer:

No external processes.

Question (exec-introspection): Does your module use any kind of runtime type information (instanceof, work with java.lang.Class, etc.)?
Answer:

No

Question (exec-threading): What threading models, if any, does your module adhere to?
Answer:

All API classes are thread safe.

Question (security-policy): Does your functionality require modifications to the standard policy file?
Answer:

No

Question (security-grant): Does your code grant additional rights to some other code?
Answer:

No

Format of files and protocols

Question (format-types): 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?
Answer:

There's a private XML file for user settings for each palette model.

Question (format-dnd): Which protocols (if any) does your code understand during Drag & Drop?
Answer:

Palette extends the default drag'n'drop implementation from Nodes. When an item is being dragged from the palette to editor window the Transferable is provided by the default Node.drag() method and a another data flavor is added (see PaletteController.ITEM_DATA_FLAVOR) which contains the Lookup of dragged item's Node.
When user drags anything from editor and drops it to palette to create a new item then the dropped Transferable must provide appropriate PasteType (see Node.getDropType()).

Question (format-clipboard): Which data flavors (if any) does your code read from or insert to the clipboard (by access to clipboard on means calling methods on java.awt.datatransfer.Transferable?
Answer:

Palette extends the default clipboard implementation from Nodes. When a palette item (Node) is copied/cut to clipboard it adds another data flavor to Transferable created by the default Node implementation, see PaletteController.ITEM_DATA_FLAVOR. The transfer data for this flavor is the Lookup of item's Node.

Performance and Scalability

Question (perf-startup): Does your module run any code on startup?
Answer:

No

Question (perf-exit): Does your module run any code on exit?
Answer:

No

Question (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?
Answer:

The default palette model implementation is based on Nodes, therefore the performance criteria are the same as those for Nodes.

Question (perf-limit): Are there any hard-coded or practical limits in the number or size of elements your code can handle?
Answer:

No

Question (perf-mem): How much memory does your component consume? Estimate with a relation to the number of windows, etc.
Answer:

Depends on the palette contents provided by palette clients. The Palette module provides only user interface for the palette contents.

Question (perf-wakeup): Does any piece of your code wake up periodically and do something even when the system is otherwise idle (no user interaction)?
Answer:

No

Question (perf-progress): Does your module execute any long-running tasks?
Answer:

Depends on the palette contents provided by palette clients. When the palette contents is being switched (i.e. user activates a different editor) the palette UI must display icons and/or names for items in expanded categories. This is being done in AWT thread. On the other hand the palette can show only a limited number of items according to screen resolution so there will be only a limited number of of requests for item's name and icon during this switch.

Question (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?
Answer:

There's a 'Palette Customizer' dialog window that displays hierarchy of palette contents (categories and their items) and contains some buttons to customize the palette contents. The Palette Customizer window design depends on the final version of the UI specification.

Question (perf-menus): Does your module use dynamically updated context menus, or context-sensitive actions with complicated and slow enablement logic?
Answer:

No

Question (perf-spi): How the performance of the plugged in code will be enforced?
Answer:

Just javadoc recommendations.