NetBeans Architecture Answers for Nodes API module

General Information

Question (arch-what): What is this project good for?
Answer: Nodes API serves as the main aparatus for visualisation of objects in NetBeans. Nodes augment objects with standard aspects used for visualisation (e.g. name, displayName, icons, set of proerties, subnodes hierarchy, etc.) Once a Node is defined for given object it can be visualised using diferent views e.g. trees, lists, tables etc. Descripion of nodes can be found here.
Question (arch-overall): Describe the overall architecture.
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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:

For general overview of the concepts related to nodes and explorers, together with code samples, see chapter 7, of NetBeans Platform for Beginners by Jason Wexbridge and Walter Nyland.

Question (arch-time): What are the time estimates of the work?
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Question (arch-quality): How will the quality of your code be tested and how are future regressions going to be prevented?
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Question (arch-where): Where one can find sources for your module?
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Project and platform dependencies

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

The default answer to this question is:


These modules are required in project.xml:

• org.openide.awt - The module is needed for compilation. The module is used during runtime. Specification version 7.33 is required.
• DialogsAPI - The module is needed for compilation. The module is used during runtime. Specification version 6.2 is required.
• FilesystemsAPI - The module is needed for compilation. The module is used during runtime. Specification version 9.0 is required.
• UtilitiesAPI - The module is needed for compilation. The module is used during runtime. Specification version 9.3 is required.
• WeakListener.setAccessible - The module is needed for compilation. The module is used during runtime. Specification version 9.3 is required.
• LookupAPI - The module is needed for compilation. The module is used during runtime. Specification version 8.0 is required.
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: Any
Question (dep-jre): Which version of JRE do you need (1.2, 1.3, 1.4, etc.)?
Answer: 1.3
Question (dep-jrejdk): Do you require the JDK or is the JRE enough?
Answer: JRE

Deployment

Question (deploy-jar): Do you deploy just module JAR file(s) or other files as well?
Answer: The API portion is inside openide.jar
Question (deploy-nbm): Can you deploy an NBM via the Update Center?
Answer: Yes (as part of openide.nbm and core.nbm).
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: Must be installed in the shared location as it is part of the very core of NetBeans.
Question (deploy-packages): Are packages of your module made inaccessible by not declaring them public?
Answer: NodesAPI is a public package.
Question (deploy-dependencies): 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)?
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Compatibility with environment

Question (compat-i18n): Is your module correctly internationalized?
Answer: Yes
Question (compat-standards): Does the module implement or define any standards? Is the implementation exact or does it deviate somehow?
Answer: Defines and implements NetBeans NodesAPI.
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: Nodes API itself does not use any kind of settings. Displayed nodes are persisted using serialization by default, but this can be changed by developers by providing own persistence mechanism.
Question (compat-deprecation): How the introduction of your project influences functionality provided by previous version of the product?
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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: No
Question (resources-read): Does your module read any resources from layers? For what purpose?
Answer: No
Question (resources-mask): Does your module mask/hide/override any resources provided by other modules in their layers?
Answer: No
Question (resources-preferences): 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 ?
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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: Nodes use lookup to communicate with other components. Each node contains own lookup wich is used for augmenting nodes with extended functionality and data. Nodes do not depend on content of other Lookups.
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? On a similar note, is there something interesting that you pass to java.util.logging.Logger? Or do you observe what others log?
Answer: No
Question (exec-component): Is execution of your code influenced by any (string) property of any of your components?
Answer: BeanNode which serves for default visualisation of JavaBeans uses the "helpID", "propertiesHelpID" and "expertHelpID" form BeanDescriptor of given bean. to link with help files. helpID - For providing help sets for JavaBeans propertiesHelpID - For providing help sets for JavaBeans proerties expertHelpID - For providing help sets for JavaBeans properties
Question (exec-ant-tasks): Do you define or register any ant tasks that other can use?
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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:

BeanNode obviously depends on reflection to get values of beans properties, which shouldn't be considered lack of API. Same applyies to PropertySupport and IndexedPropertySupport.

ProjectManagerMutex -

A test in Children checks that org.netbeans.api.project.ProjectManager.mutex() is not held by the current thread when acquiring Children.MUTEX. Since this module cannot depend on the module providing ProjectManager, the test uses reflection to retrieve the ProjectManager.mutex() instance.

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
Question (exec-introspection): Does your module use any kind of runtime type information (instanceof, work with java.lang.Class, etc.)?
Answer: Yes.
• instanceof: 37 occurences
• isAssgnableFrom: 5 occurences
• isInstance: 3 occurences
Question (exec-threading): What threading models, if any, does your module adhere to? How the project behaves with respect to threading?
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Question (security-policy): Does your functionality require modifications to the standard policy file?
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Question (security-grant): Does your code grant additional rights to some other code?
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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: None
Question (format-dnd): Which protocols (if any) does your code understand during Drag & Drop?
Answer: Nodes provide default implementation of d'n'd operations on nodes. This can be extendeded by specific implementation of nodes by overloading: Node.drag() Node.getDropTye() Default Transferables for nodes can be obtained using. NodeTransfer class The NodeTransfer.Paste interface serves as an intelligent source of paste types for a target node.
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: Nodes provide default implementation of clipboard operations on nodes. This can be extendeded by specific implementation of nodes by overloading: Node.clipboardCopy(), Node.cliboardCut(), Node.getPasteTypes() Default Transferables for nodes can be obtained using. NodeTransfer class

IndexedCustomizer provides own DataFlavor transfering indices.

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: Not directly. State of nodes can be serialized as result of window system serialization.
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: Number of visiualized objects and complexity of the visualised objects.
Question (perf-limit): Are there any hard-coded or practical limits in the number or size of elements your code can handle?
Answer: All nodes are held in memory during the IDE runtime, there is no swap/cache mechanism for nodes.
Question (perf-mem): How much memory does your component consume? Estimate with a relation to the number of windows, etc.
Answer: Fully initialized node can contain relatively big amount of other objects e.g. objects in lookups, properties, etc. Depending on th Node's subclass.
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: No
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: No
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?
WARNING: Question with id="perf-spi" has not been answered!