Slicer3:EventBroker - Revision history

Grundlett: Text replacement - "http://www.slicer.org/slicerWiki/index.php/" to "https://www.slicer.org/wiki/"

2017-07-10T17:15:22Z

Text replacement - "http://www.slicer.org/slicerWiki/index.php/" to "https://www.slicer.org/wiki/"

Marianna: Protected "Slicer3:EventBroker" [edit=sysop:move=sysop]

2008-05-22T16:27:11Z

Protected "Slicer3:EventBroker" [edit=sysop:move=sysop]

Marianna: Replacing page with ''''Note:''' We are migrating this content to the slicer.org domain - The newer page is [http://www.slicer.org/slicerWiki/index.php/Slicer3:EventBroker...'

2008-05-22T16:27:06Z

Replacing page with '<big>'''Note:''' We are migrating this content to the slicer.org domain - <font color="orange">The newer page is [http://www.slicer.org/slicerWiki/index.php/Slicer3:EventBroker...'

Marianna: Reverted edits by Marianna (Talk); changed back to last version by Pieper

2008-05-22T13:44:20Z

Reverted edits by Marianna (Talk); changed back to last version by Pieper

Marianna: Replacing page with ''''Note:''' We are migrating this content to the slicer.org domain - The newer page is [http://www.slicer.org/slicerWiki/index.php/Slicer3:EventBroker...'

2008-05-19T19:22:02Z

Pieper at 14:20, 24 April 2008

2008-04-24T14:20:27Z

Pieper: /* References */

2008-04-07T13:58:30Z

References

Pieper: /* EventBroker Solution */

2008-04-07T13:57:48Z

EventBroker Solution

Pieper: /* EventBroker Solution */

2008-04-04T20:28:38Z

EventBroker Solution

Pieper: /* EventBroker Solution */

2008-04-04T20:27:53Z

EventBroker Solution

← Older revision		Revision as of 17:15, 10 July 2017
Line 1:		Line 1:
−	<big>'''Note:''' We are migrating this content to the slicer.org domain - <font color="orange">The newer page is [~~http~~://www.slicer.org/~~slicerWiki/index.php~~/Slicer3:EventBroker here]</font></big>	+	<big>'''Note:''' We are migrating this content to the slicer.org domain - <font color="orange">The newer page is [https://www.slicer.org/wiki/Slicer3:EventBroker here]</font></big>

← Older revision		Revision as of 16:27, 22 May 2008
Line 1:		Line 1:
−	~~== Currently ==~~	+	<big>'''Note:''' We are migrating this content to the slicer.org domain - <font color="orange">The newer page is [http://www.slicer.org/slicerWiki/index.php/Slicer3:EventBroker here]</font></big>
−	~~The basic idea of the EventBroker is to avoid the following kind of code that shows up in GUIs and other classes that depend on events generated by other classes:~~
−
−	~~node-~~>~~AddObserver(vtkCommand::ModifiedEvent, callbackCommand)~~
−
−	~~== Problems ==~~
−
−	~~The problems with this:~~
−
−	* node 'owns' the observer, but the callbackCommand is opaque so it doesn'~~t know anything about what will happen when the event is invoked~~
−
−	* the GUI needs to explicitly remove the observer before it is destroyed
−
−	* node is not introspectable; you cannot get a list of observers on the node (all data and methods are private)
−
−	* there'~~s no easy way to know what side effects will happen for any Set call (either a priori or experimentally).~~
−
−	* there'~~s no way to collapse events or disable them~~
−
−	~~== EventBroker Solution ==~~
−
−	~~The EventBroker is a singleton, available as~~:
−
−	~~vtkEventBroker *broker = vtkEventBroker::GetInstance();~~
−
−	~~with the broker, you can make a call like the following:~~
−
−	~~broker->AddObservation(node, vtkCommand::ModifiedEvent, this, callbackCommand);~~
−
−	~~where~~ '~~'node'' is the subject of the observation.~~
−
−	~~The broker does the following:~~
−
−	* adds DeleteEvent observers to both ''node'' and ''this~~'' so it can remove the observation automatically when either side is destroyed~~
−
−	* keeps an introspectable list of all observers it knows about
−
−	* has an option to ~~keep a log of all event invocations for debugging and performance analysis~~
−
−	* has an option to turn off all event invocations
−
−	* has an ''asynchronous'' option to queue all event invocations and invoke them later (off by default)
−
−	* has option to collapse redundant events in the ~~queue~~
−
−	~~The broker is also available for use from tcl~~. ~~For convenience in slicer there's a global variable for the broker so you can use a code snippet like:~~
−
−	~~$::slicer3::Broker AddObservation $node ModifiedEvent {puts~~ "~~the node was modified~~"}
−
−	~~Another nice feature~~ is that you can use a numerical value for the event argument, which works around the limitation in VTK's native wrapping of event types. So, if you look in the header for a widget or object and know the custom event number, you can use it as an argument:
−
−	~~$::slicer3::Broker AddObservation $node 1 {puts "got an AnyEvent notification from the node"}~~
−
−	~~Future options include:~~
−
−	* add a timer to log the amount of time taken to process each event
−
−	* specify that some observations must be handled synchronously (e.g. for progress events that shouldn't be collapsed)
−
−	~~See the file~~ [http://www.~~na-mic~~.org/~~Slicer/Documentation/Slicer3/html/classvtkEventBroker.html Libs/MRML/vtkEventBroker.h] for more information on logging options and introspection features.~~
−
−	~~==References==~~
−
−	~~The following reference provided insight on requirements and design precedents.~~
−
−	* [http://java.sun.com/products/jms/javadoc-102a/index.~~html Java Message Service (JMS) API]~~
−	* [http:/~~/en.wikipedia.org/wiki/Observer_pattern Wikipedia definition of Observer Pattern]~~
−	* [http:~~//xlobject.sourceforge.net/ A C++ implementation]~~
−	* [http://sigslot.sourceforge.net/ Another C++ implementation]
−	* [http://doc.trolltech.com/4.3/signalsandslots.html The Qt implementation]
−
−	~~==Dependency Graphs==~~
−
−	EventBroker code should have the option to put out log files that are compatible with [http://www.graphviz.org graphviz] .dot file format. This can be rendered with a variety of programs, or even pasted directly in the wiki:
−
−	~~=== Simple Dependency ===~~
−	~~<graphviz border='frame' format='svg'>~~
−	~~digraph G {~~
−	~~vtkImageViewer -> vtkImageEllipsoidSource[ label = ModifiedEvent~~ ]
−	;}
−	</~~graphviz~~>
−
−	~~=== Subset of Slicer Dependencies ===~~
−	~~<graphviz border='frame' format='svg'>~~
−	~~strict digraph G {~~
−	~~vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLScalarVolumeDisplayNode -> vtkMRMLScalarVolumeDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLLabelMapVolumeDisplayNode -> vtkMRMLLabelMapVolumeDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLDiffusionWeightedVolumeDisplayNode -> vtkMRMLDiffusionWeightedVolumeDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLDiffusionTensorVolumeDisplayNode -> vtkMRMLDiffusionTensorVolumeDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLFiberBundleLineDisplayNode -> vtkMRMLFiberBundleLineDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLFiberBundleTubeDisplayNode -> vtkMRMLFiberBundleTubeDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLFiberBundleGlyphDisplayNode -> vtkMRMLFiberBundleGlyphDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLCameraNode -> vtkOpenGLCamera [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLUnstructuredGridDisplayNode -> vtkMRMLUnstructuredGridDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLCameraNode -> vtkOpenGLCamera [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLCameraNode -> vtkOpenGLCamera [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkImageData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkImageData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkImageData [ label = "ModifiedEvent" ]~~
−	;}
−	</~~graphviz~~>
−
−	~~== Issues ==~~
−
−	* how to work with the vtkObserverManager?

← Older revision		Revision as of 13:44, 22 May 2008
Line 1:		Line 1:
−	~~<big~~>'''~~Note~~:''' ~~We are migrating~~ this ~~content~~ to the slicer.~~org domain - <font color=~~"~~orange~~"~~>The newer page is~~ [http://www.~~slicer~~.org/~~slicerWiki~~/index.~~php~~/~~Slicer3~~:EventBroker ~~here~~]</~~font~~></~~big~~>a	+	== Currently ==
		+	The basic idea of the EventBroker is to avoid the following kind of code that shows up in GUIs and other classes that depend on events generated by other classes:
		+
		+	node->AddObserver(vtkCommand::ModifiedEvent, callbackCommand)
		+
		+	== Problems ==
		+
		+	The problems with this:
		+
		+	* node 'owns' the observer, but the callbackCommand is opaque so it doesn't know anything about what will happen when the event is invoked
		+
		+	* the GUI needs to explicitly remove the observer before it is destroyed
		+
		+	* node is not introspectable; you cannot get a list of observers on the node (all data and methods are private)
		+
		+	* there's no easy way to know what side effects will happen for any Set call (either a priori or experimentally).
		+
		+	* there's no way to collapse events or disable them
		+
		+	== EventBroker Solution ==
		+
		+	The EventBroker is a singleton, available as:
		+
		+	vtkEventBroker *broker = vtkEventBroker::GetInstance();
		+
		+	with the broker, you can make a call like the following:
		+
		+	broker->AddObservation(node, vtkCommand::ModifiedEvent, this, callbackCommand);
		+
		+	where ''node'' is the subject of the observation.
		+
		+	The broker does the following:
		+
		+	* adds DeleteEvent observers to both ''node'' and ''this'' so it can remove the observation automatically when either side is destroyed
		+
		+	* keeps an introspectable list of all observers it knows about
		+
		+	* has an option to keep a log of all event invocations for debugging and performance analysis
		+
		+	* has an option to turn off all event invocations
		+
		+	* has an ''asynchronous'' option to queue all event invocations and invoke them later (off by default)
		+
		+	* has option to collapse redundant events in the queue
		+
		+	The broker is also available for use from tcl. For convenience in slicer there's a global variable for the broker so you can use a code snippet like:
		+
		+	$::slicer3::Broker AddObservation $node ModifiedEvent {puts "the node was modified"}
		+
		+	Another nice feature is that you can use a numerical value for the event argument, which works around the limitation in VTK's native wrapping of event types. So, if you look in the header for a widget or object and know the custom event number, you can use it as an argument:
		+
		+	$::slicer3::Broker AddObservation $node 1 {puts "got an AnyEvent notification from the node"}
		+
		+	Future options include:
		+
		+	* add a timer to log the amount of time taken to process each event
		+
		+	* specify that some observations must be handled synchronously (e.g. for progress events that shouldn't be collapsed)
		+
		+	See the file [http://www.na-mic.org/Slicer/Documentation/Slicer3/html/classvtkEventBroker.html Libs/MRML/vtkEventBroker.h] for more information on logging options and introspection features.
		+
		+	==References==
		+
		+	The following reference provided insight on requirements and design precedents.
		+
		+	* [http://java.sun.com/products/jms/javadoc-102a/index.html Java Message Service (JMS) API]
		+	* [http://en.wikipedia.org/wiki/Observer_pattern Wikipedia definition of Observer Pattern]
		+	* [http://xlobject.sourceforge.net/ A C++ implementation]
		+	* [http://sigslot.sourceforge.net/ Another C++ implementation]
		+	* [http://doc.trolltech.com/4.3/signalsandslots.html The Qt implementation]
		+
		+	==Dependency Graphs==
		+
		+	EventBroker code should have the option to put out log files that are compatible with [http://www.graphviz.org graphviz] .dot file format. This can be rendered with a variety of programs, or even pasted directly in the wiki:
		+
		+	=== Simple Dependency ===
		+	<graphviz border='frame' format='svg'>
		+	digraph G {
		+	vtkImageViewer -> vtkImageEllipsoidSource[ label = ModifiedEvent ]
		+	;}
		+	</graphviz>
		+
		+	=== Subset of Slicer Dependencies ===
		+	<graphviz border='frame' format='svg'>
		+	strict digraph G {
		+	vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLScalarVolumeDisplayNode -> vtkMRMLScalarVolumeDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLLabelMapVolumeDisplayNode -> vtkMRMLLabelMapVolumeDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLDiffusionWeightedVolumeDisplayNode -> vtkMRMLDiffusionWeightedVolumeDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLDiffusionTensorVolumeDisplayNode -> vtkMRMLDiffusionTensorVolumeDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLFiberBundleLineDisplayNode -> vtkMRMLFiberBundleLineDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLFiberBundleTubeDisplayNode -> vtkMRMLFiberBundleTubeDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLFiberBundleGlyphDisplayNode -> vtkMRMLFiberBundleGlyphDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLCameraNode -> vtkOpenGLCamera [ label = "ModifiedEvent" ]
		+	; vtkMRMLUnstructuredGridDisplayNode -> vtkMRMLUnstructuredGridDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLCameraNode -> vtkOpenGLCamera [ label = "ModifiedEvent" ]
		+	; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLCameraNode -> vtkOpenGLCamera [ label = "ModifiedEvent" ]
		+	; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]
		+	; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]
		+	; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLModelDisplayNode -> vtkImageData [ label = "ModifiedEvent" ]
		+	; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]
		+	; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLModelDisplayNode -> vtkImageData [ label = "ModifiedEvent" ]
		+	; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]
		+	; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]
		+	; vtkMRMLModelDisplayNode -> vtkImageData [ label = "ModifiedEvent" ]
		+	;}
		+	</graphviz>
		+
		+	== Issues ==
		+
		+	* how to work with the vtkObserverManager?

← Older revision		Revision as of 19:22, 19 May 2008
Line 1:		Line 1:
−	~~== Currently ==~~	+	<big>'''Note:''' We are migrating this content to the slicer.org domain - <font color="orange">The newer page is [http://www.slicer.org/slicerWiki/index.php/Slicer3:EventBroker here]</font></big>a
−	~~The basic idea of the EventBroker is to avoid the following kind of code that shows up in GUIs and other classes that depend on events generated by other classes:~~
−
−	~~node->AddObserver(vtkCommand::ModifiedEvent, callbackCommand)~~
−
−	~~== Problems ==~~
−
−	~~The problems with this:~~
−
−	* node 'owns' the observer, but the callbackCommand is opaque so it doesn't know anything about what will happen when the event is invoked
−
−	* the GUI needs to explicitly remove the observer before it is destroyed
−
−	* node is not introspectable; you cannot get a list of observers on the node (all data and methods are private)
−
−	* there's no easy way to know what side effects will happen for any Set call (either a priori or experimentally).
−
−	* there's no way to collapse events or disable them
−
−	~~== EventBroker Solution ==~~
−
−	~~The EventBroker is a singleton, available as:~~
−
−	~~vtkEventBroker *broker = vtkEventBroker::GetInstance();~~
−
−	~~with the broker, you can make a call like the following:~~
−
−	~~broker-~~>~~AddObservation(node, vtkCommand::ModifiedEvent, this, callbackCommand);~~
−
−	~~where '~~'~~node~~'' ~~is the subject of the observation.~~
−
−	~~The broker does the following~~:
−
−	* adds DeleteEvent observers to both '~~'node'' and~~ ''this~~'' so it can remove the observation automatically when either side is destroyed~~
−
−	* keeps an introspectable list of all observers it knows about
−
−	* has an option to keep a log of all event invocations for debugging and performance analysis
−
−	* has an option to turn off all event invocations
−
−	* has an ''asynchronous'' option to queue all event invocations and invoke them later (off by default)
−
−	* has option to ~~collapse redundant events in~~ the ~~queue~~
−
−	~~The broker is also available for use from tcl~~. ~~For convenience in slicer there's a global variable for the broker so you can use a code snippet like:~~
−
−	~~$::slicer3::Broker AddObservation $node ModifiedEvent {puts~~ "~~the node was modified~~"}
−
−	~~Another nice feature~~ is that you can use a numerical value for the event argument, which works around the limitation in VTK's native wrapping of event types. So, if you look in the header for a widget or object and know the custom event number, you can use it as an argument:
−
−	~~$::slicer3::Broker AddObservation $node 1 {puts "got an AnyEvent notification from the node"}~~
−
−	~~Future options include:~~
−
−	* add a timer to log the amount of time taken to process each event
−
−	* specify that some observations must be handled synchronously (e.g. for progress events that shouldn't be collapsed)
−
−	~~See the file~~ [http://www.~~na-mic~~.org/~~Slicer/Documentation/Slicer3/html/classvtkEventBroker.html Libs/MRML/vtkEventBroker.h] for more information on logging options and introspection features.~~
−
−	~~==References==~~
−
−	~~The following reference provided insight on requirements and design precedents.~~
−
−	* [http://java.sun.com/products/jms/javadoc-102a/index.~~html Java Message Service (JMS) API]~~
−	* [http:/~~/en.wikipedia.org/wiki/Observer_pattern Wikipedia definition of Observer Pattern]~~
−	* [http://xlobject.sourceforge.net/ A C++ implementation]
−	* [http://sigslot.sourceforge.net/ Another C++ implementation]
−	* [http:~~//doc.trolltech.com/4.3/signalsandslots.html The Qt implementation]~~
−
−	~~==Dependency Graphs==~~
−
−	EventBroker ~~code should have the option to put out log files that are compatible with [http://www.graphviz.org graphviz] .dot file format.~~ ~~This can be rendered with a variety of programs, or even pasted directly in the wiki:~~
−
−	~~=== Simple Dependency ===~~
−	~~<graphviz border='frame' format='svg'>~~
−	~~digraph G {~~
−	~~vtkImageViewer -> vtkImageEllipsoidSource[ label = ModifiedEvent~~ ]
−	;}
−	</~~graphviz~~>
−
−	~~=== Subset of Slicer Dependencies ===~~
−	~~<graphviz border='frame' format='svg'>~~
−	~~strict digraph G {~~
−	~~vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLScalarVolumeDisplayNode -> vtkMRMLScalarVolumeDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLLabelMapVolumeDisplayNode -> vtkMRMLLabelMapVolumeDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLDiffusionWeightedVolumeDisplayNode -> vtkMRMLDiffusionWeightedVolumeDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLDiffusionTensorVolumeDisplayNode -> vtkMRMLDiffusionTensorVolumeDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLFiberBundleLineDisplayNode -> vtkMRMLFiberBundleLineDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLFiberBundleTubeDisplayNode -> vtkMRMLFiberBundleTubeDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLFiberBundleGlyphDisplayNode -> vtkMRMLFiberBundleGlyphDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLCameraNode -> vtkOpenGLCamera [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLUnstructuredGridDisplayNode -> vtkMRMLUnstructuredGridDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLCameraNode -> vtkOpenGLCamera [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLCameraNode -> vtkOpenGLCamera [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkImageData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkImageData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelNode -> vtkPolyData [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkMRMLModelDisplayNode [ label = "ModifiedEvent" ]~~
−	~~; vtkMRMLModelDisplayNode -> vtkImageData [ label = "ModifiedEvent" ]~~
−	;}
−	</~~graphviz~~>
−
−	~~== Issues ==~~
−
−	* how to work with the vtkObserverManager?

@@ Line 1: / Line 1: @@
 == Currently ==
-The basic idea of the EventBroker is that currently we have a lot of this kind of code in GUIs:
+The basic idea of the EventBroker is to avoid the following kind of code that shows up in GUIs and other classes that depend on events generated by other classes:
   node->AddObserver(vtkCommand::ModifiedEvent, callbackCommand)
@@ Line 12: / Line 12: @@
 * the GUI needs to explicitly remove the observer before it is destroyed
-* node is not introspectable; you cannot get a list of observers on the node
+* node is not introspectable; you cannot get a list of observers on the node (all data and methods are private)
 * there's no easy way to know what side effects will happen for any Set call (either a priori or experimentally).
@@ Line 46: / Line 46: @@
 The broker is also available for use from tcl.  For convenience in slicer there's a global variable for the broker so you can use a code snippet like:
-  $::slicer3::broker AddObservation $node ModifiedEvent {puts "$node was modified"}
+  $::slicer3::Broker AddObservation $node ModifiedEvent {puts "the node was modified"}
 Future options include:
 * add a timer to log the amount of time taken to process each event
 See the file [http://www.na-mic.org/Slicer/Documentation/Slicer3/html/classvtkEventBroker.html Libs/MRML/vtkEventBroker.h] for more information on logging options and introspection features.

← Older revision	Revision as of 16:27, 22 May 2008
(No difference)

← Older revision		Revision as of 13:58, 7 April 2008
Line 55:		Line 55:

	==References==		==References==
		+
		+	The following reference provided insight on requirements and design precedents.

	* [http://java.sun.com/products/jms/javadoc-102a/index.html Java Message Service (JMS) API]		* [http://java.sun.com/products/jms/javadoc-102a/index.html Java Message Service (JMS) API]

@@ Line 52: / Line 52: @@
 * add a timer to log the amount of time taken to process each event
-See the file Libs/MRML/vtkEventBroker.h for more information on logging options and introspection features.
+See the file [http://www.na-mic.org/Slicer/Documentation/Slicer3/html/classvtkEventBroker.html Libs/MRML/vtkEventBroker.h] for more information on logging options and introspection features.
 ==References==

← Older revision		Revision as of 20:28, 4 April 2008
Line 51:		Line 51:

	* add a timer to log the amount of time taken to process each event		* add a timer to log the amount of time taken to process each event
		+
		+	See the file Libs/MRML/vtkEventBroker.h for more information on logging options and introspection features.

	==References==		==References==

← Older revision		Revision as of 20:27, 4 April 2008
Line 43:		Line 43:

	* has option to collapse redundant events in the queue		* has option to collapse redundant events in the queue
		+
		+	The broker is also available for use from tcl. For convenience in slicer there's a global variable for the broker so you can use a code snippet like:
		+
		+	$::slicer3::broker AddObservation $node ModifiedEvent {puts "$node was modified"}

	Future options include:		Future options include: