Provides common APIs to execute external process in the IDE to handle its streams and present the output to the user. Input/line processing can be used as separate part.Question (arch-overall): Describe the overall architecture. Answer:
The External Execution module provides the ExternalExecutionAPI that contains support for execution of external processes in the IDE. It also provide support class for the actual creation of the external process and support for destroying the process tree. There is also abstraction of process builder.
Another exported API ExternalExecutionInputAPI define interfaces for input processing (character or line based) and provides common implementations of these with factory methods.
Natural extension to input processing API is printing API
that defines interfaces transforming lines to lines printed to
org.openide.windows.OutputWriter. API provides common implementations too.
The SPI ExternalExecutionSPI allows different implementations of process builder.
There is also SPI allowing to register support for destroying the process tree ExternalExecutionDestroySPI.
The ExternalExecutionOpenSPI allows implementation module to determine particular way of file or HTTP URL opening in predefined covertors. It also makes options dialog opening pluggable.
There is also API to provide additional startup arguments to interested clients such as projects and servers ExternalExecutionStartupAPI. Th corresponding SPI for plugins which need to provide such additional arguments is also available as ExternalExecutionStartupSPI.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:
Client needs to execute an external process and handle process streams and display the output in the output tab.
In order to achieve this client creates the ExecutionDescriptor. Via this object client configures all the UI behaviour of the subsequent execution. As a next step client creates the ExecutionService itself and calls run to execute the job. Run can be called multiple times. The output and input streams are presented in output tab. Additional processing and printing conversion can be configured in descriptor through interfaces described in following usecases.
The creation of the external process is supported by ExternalProcessBuilder to make things easier.
Client needs to process character data coming from stream, file or other source.
To abstract the source of the data client must implement InputReader. To abstract the data processing client must implement InputProcessor or LineProcessor. For all three interfaces there are prepared common implementations (and bridge from character based to line based processing) at these three factory classes:
To configure additional functionality specific to
see the next usecase.
Once the data source and processing objects are prepared client creates InputReaderTask. Factory methods of the InputReaderTask can create either common task exiting on interruption or cancellation or draining task which is trying to drain out all available data before exiting.
Client intends to process input lines and print them to
In addition printed lines should be transformed (converted) somehow
and enriched by line listeners.
The both default printing processors provide factory method accepting LineConvertor. Namely InputProcessors.printing(org.openide.windows.OutputWriter out, LineConvertor convertor, boolean resetEnabled) and LineProcessors.printing(org.openide.windows.OutputWriter out, LineConvertor convertor, boolean resetEnabled). Convertor is then used to convert received lines to printed ones. Common convertors (file, http) are provided in factory class LineConvertors.
Third party wants to implement custom process builder to provide additional functionality, such as remote execution.
Client wants to destroy the process, trying to kill whole process tree. Method ExternalProcessSupport.destroy(java.lang.Process process, Map<String,String> env) is designed for that. It will use a ProcessDestroyPerformer registered in default lookup to do so.
The third party plugin may want to be able provide additional arguments for the process startup in a standardized way. In order to do so it will register a implementation of StartupExtenderImplementation to the layer folder StartupExtender. The annotation StartupExtenderImplementation.Registration can be used for that.
The clients (for exmaple project or server) may query the extenders via the API class StartupExtender and use the additional arguments for the process.
Some default LineConvertors returned by LineConvertor needs to open file or URL. A bit special case is also options dialog opening required by ExecutionService to open options dialog specified by ExecutionDescriptor. To cover this three usecases in a pluggable way while keeping dependencies minimal there are three corresponding SPI classes one may implement. So there is FileOpenHandler to handle file opening, HttpOpenHandler to deal with HTTP URLs and OptionOpenHandler to open proper options dialog.Question (arch-time): What are the time estimates of the work? Answer:
Written and functional. Compatible changes can occur in future.Question (arch-quality): How will the quality of your code be tested and how are future regressions going to be prevented? Answer:
Most of the API functionality is covered by unit tests. Same applies to future enhancements.Question (arch-where): Where one can find sources for your module? Answer:
The sources for the module are in the NetBeans Mercurial repositories.
These modules are required in project.xml:
None.Question (dep-platform): On which platforms does your module run? Does it run in the same way on each? Answer:
No known platform dependencies. In future there could be need for native code in order to terminate the whole process tree created by execution of external process.Question (dep-jre): Which version of JRE do you need (1.2, 1.3, 1.4, etc.)? Answer:
1.5Question (dep-jrejdk): Do you require the JDK or is the JRE enough? Answer:
JRE is enough.
Just the single JAR file.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:
Anywhere.Question (deploy-packages): Are packages of your module made inaccessible by not declaring them public? Answer:
Only API packages are exported.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)? Answer:
Yes.Question (compat-standards): Does the module implement or define any standards? Is the implementation exact or does it deviate somehow? Answer:
No.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:
Yes. No settings stored.Question (compat-deprecation): How the introduction of your project influences functionality provided by previous version of the product? Answer:
The module languages.execution should be removed as it provides not well stabilized subset of the same functionality.
Yes.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 ? Answer:
org.openide.util.Lookupor any similar technology to find any components to communicate with? Which ones? Answer: 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:
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:
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:
Yes. The API provides support to do so. The result code, input and output stream content does not define API as this is forwarded to the client of this module.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? How the project behaves with respect to threading? Answer:
Each class and factory method defines the thread safety of the class. If this is missing by accident method can be called from any thread.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:
None.Question (format-dnd): Which protocols (if any) does your code understand during Drag & Drop? Answer:
None.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
No.Question (perf-exit): Does your module run any code on exit? Answer:
On JVM shutdown module tries to terminate any running process executed through the API.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 threads depending on number of spawned processes (n) increases lineary (4n the worst case, 2n the best case).Question (perf-limit): Are there any hard-coded or practical limits in the number or size of elements your code can handle? Answer:
Any spawned process needs 4 threads (the worst case). One as the process handler, one for the standard input, one for the standard output and one for the standard error output. The minimal number of threads to handle a process is 2 (process handler and standard output handler - standard error output is redirected to the output, no thread for the standard input).
Typically the IDE should not run more than 10 external processes concurrently.Question (perf-mem): How much memory does your component consume? Estimate with a relation to the number of windows, etc. Answer:
The small amount of the memory is consumed by caching data structures like available output tabs and currently executed processes.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:
Executing external processes. Always scheduled to dedicated thread.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? Answer:
No enforcement. SPI code may be used to terminate whole process tree.
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