Language & Concepts - Revision history

Smadar at 11:02, 23 September 2014

2014-09-23T11:02:39Z

Smadar: /* Additional Information */

2014-09-23T08:30:18Z

‎Additional Information

Smadar: /* Additional Information */

2014-09-23T08:29:07Z

‎Additional Information

Smadar: /* Additional Information */

2014-09-23T08:28:19Z

‎Additional Information

Smadar: /* Additional Information */

2014-04-29T07:04:02Z

‎Additional Information

Smadar: /* Play-Out */

2014-02-11T15:11:49Z

‎Play-Out

Smadar: /* System Model */

2014-01-02T11:25:12Z

‎System Model

Smadar: /* System Model */

2013-12-29T07:46:24Z

‎System Model

Smadar: /* Live Sequence Charts (LSC) */

2013-11-25T07:29:33Z

‎Live Sequence Charts (LSC)

Smadar: /* Live Sequence Charts (LSC) */

2013-11-25T07:29:20Z

‎Live Sequence Charts (LSC)

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 [[Image:LSCExample.png | frame | <span style="color: rgb(0, 128, 128);"><span style="font-family: Tahoma;">Figure 1: An LSC describing the basic move of a memory game. Note the red and blue elements in the diagram, indicating hot and cold LSC messages and conditions.</span> </span>]]
-PlayGo is built around the language of [http://www.wisdom.weizmann.ac.il/~harel/ live sequence charts (LSC)] and its Java derivative.
+PlayGo is a development environment for the language of [http://www.wisdom.weizmann.ac.il/~harel/ live sequence charts (LSC)] and its Java derivative.
-LSC is a visual language that extends classical message sequence charts mainly with a universal interpretation and must/may and  monitor/execute modalities. A full description of the language is given in the book [http://www.wisdom.weizmann.ac.il/~playbook/Updates/ComeLetsPlay.pdf D. Harel and R. Marelly, Come, Let's Play:  Scenario-Based Programming Using LSCs and the Play-Engine].
+LSC is a visual language that extends classical message sequence charts mainly with a universal interpretation and must/may and monitor/execute modalities. A full description of the language is given in the book [http://www.wisdom.weizmann.ac.il/~playbook/Updates/ComeLetsPlay.pdf D. Harel and R. Marelly, Come, Let's Play:  Scenario-Based Programming Using LSCs and the Play-Engine]. A language reference for the Java derivative implemented in PlayGo can be found [[Media:LSC Language Reference PlayGo.pdf | here]].
-Objects in LSCs are represented by vertical lines, called lifeline. A lifeline can represent a concrete object or can stand for a set of objects that participate in the scenario. A special type of lifeline represents the user or the environment.
+An LSC system consists of scenarios, each of which describes a facet of the system’s behavior. Every scenario is described in a live sequence chart (an LSC). The overall system behavior is the result of concurrent execution of all LSCs.
-Messages in LSCs are represented by horizontal arrows between the participating lifelines. Conditional guards, showing up as elongated hexagons, specify statements that are to be true when reached. In addition LSCs may contain assignments and structural constructs (e.g. loops).
+Objects in LSCs are represented by vertical lines, called lifelines. A lifeline can represent a concrete object or can denote a set of objects that participate in the scenario. Special kinds of lifelines represents the user and the environment.
-The overall effect of a chart is to specify a scenario of behavior, consisting of messages flowing between objects and things having to be true along the way.
+Messages in LSCs are represented by horizontal arrows between the participating lifelines. Messages can be tagged as to whether they must occur or may occur (hot vs. cold) and whether they are to be executed at that point of the scenario or only waited for (execute vs. monitor).
 == Play-In ==
 Play-in is the process introduced in [http://www.wisdom.weizmann.ac.il/~playbook/ Come, Let's Play] for creating (specifying) scenarios by directly manipulating objects in the GUI of the system under development. Thus, play-in is the means for '''programming''' a scenario-based system.

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 To learn how to create a system model, click [[How_to_create_a_system_model | here]].
-== Additional Information ==
+== Language Reference and Additional Information ==
 Additional links and papers on the underlying languages and ideas, as well as on on-going relevant research, can be found on [http://www.wisdom.weizmann.ac.il/~harel David Harel's website]
 An LSC Language reference is available for download [[Media:LSC Language Reference PlayGo.pdf | here]].

← Older revision		Revision as of 08:29, 23 September 2014
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	Additional links and papers on the underlying languages and ideas, as well as on on-going relevant research, can be found on [http://www.wisdom.weizmann.ac.il/~harel David Harel's website]		Additional links and papers on the underlying languages and ideas, as well as on on-going relevant research, can be found on [http://www.wisdom.weizmann.ac.il/~harel David Harel's website]

−	An LSC Language reference ~~manual~~ is available for download [[Media:LSC Language Reference PlayGo.pdf \| here]].	+	An LSC Language reference is available for download [[Media:LSC Language Reference PlayGo.pdf \| here]].

← Older revision		Revision as of 08:28, 23 September 2014
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	Additional links and papers on the underlying languages and ideas, as well as on on-going relevant research, can be found on [http://www.wisdom.weizmann.ac.il/~harel David Harel's website]		Additional links and papers on the underlying languages and ideas, as well as on on-going relevant research, can be found on [http://www.wisdom.weizmann.ac.il/~harel David Harel's website]

−	An LSC Language reference manual is available for download [[~~LSC_Reference~~ \| here]].	+	An LSC Language reference manual is available for download [[Media:LSC Language Reference PlayGo.pdf \| here]].

← Older revision		Revision as of 07:04, 29 April 2014
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	== Additional Information ==		== Additional Information ==
	Additional links and papers on the underlying languages and ideas, as well as on on-going relevant research, can be found on [http://www.wisdom.weizmann.ac.il/~harel David Harel's website]		Additional links and papers on the underlying languages and ideas, as well as on on-going relevant research, can be found on [http://www.wisdom.weizmann.ac.il/~harel David Harel's website]
		+
		+	An LSC Language reference manual is available for download [[LSC_Reference \| here]].

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 == Play-Out  ==
-Play-out is the method introduced in [http://www.wisdom.weizmann.ac.il/~playbook/ Come, Let's Play] for executing LSC specifications. Thus, play-out is the means for '''running''' a scenario-based program. Every execution of an operation is considered a step. Following a user action, the system executes a superstep - a sequence of the steps that follows the user action, and which terminates either at a stable situation where the next event is a user action, or when the entire execution terminates. <br><br>During play-out, the current state of each LSC is represented by a cut. Given the scenario-based nature of the specification, a cut may induce multiple events to be simultaneously enabled for execution. In this case, the play-out mechanism chooses the event to execute based on some strategy. In the "naïve" play-out technique, such choices are made nondeterministically, and may lead to violations. In the smarter play-out algorithms, the next step is carefully computed, using model checking or planning, in order to help avoid violations. <br><br>The current version of PlayGo implements naïve play-out, and does so via compilation. PlayGo uses a variant of the [http://www.wisdom.weizmann.ac.il/~maozs/s2a/ S2A Compiler], which transforms LSCs into AspectJ code. During compilation, each LSC is statically analyzed, and is translated into a scenario aspect that simulates an automaton whose states represent cuts and whose transitions are triggered by aspect pointcuts. Scenario aspects are locally responsible for listening out for relevant events and advancing the cut state accordingly. The compilation scheme generates a coordinator, implemented as a separate aspect, which observes the cut state changes of all active scenario aspects, chooses a method, and executes it. Also, S2A follows the "strategy" design pattern to enable integration of various strategies. [[PlayGo Demos#Play-Out|Watch a Play-Out demo]]
+Play-out is the method introduced in [http://www.wisdom.weizmann.ac.il/~playbook/ ''Come, Let's Play''] for executing LSC specifications. Thus, play-out is the means for '''running''' a scenario-based program. Every execution of an operation is considered a step. Following a user action, the system executes a superstep - a sequence of the steps that follows the user action, and which terminates either at a stable situation, where the next event is a user action, or when the entire execution terminates. <br><br>During play-out, the current state of each LSC is represented by a cut. Given the scenario-based nature of the specification, a cut may induce multiple events to be simultaneously enabled for execution. In this case, the play-out mechanism chooses the event to execute based on some strategy. In the "naïve" play-out technique, such choices are made nondeterministically, and may lead to violations. In the smarter play-out algorithms, the next step is carefully computed, using model checking or planning, in order to help avoid violations. <br><br>PlayGo implements play-out via compilation. It uses a variant of the [http://www.wisdom.weizmann.ac.il/~maozs/s2a/ S2A Compiler], which transforms LSCs into AspectJ code. During compilation, each LSC is statically analyzed, and is translated into a scenario aspect that simulates an automaton whose states represent cuts and whose transitions are triggered by aspect pointcuts. Scenario aspects are locally responsible for listening out for relevant events and advancing the cut state accordingly. The compilation scheme generates a coordinator, implemented as a separate aspect, which observes the cut state changes of all active scenario aspects, chooses a method, and executes it. Also, S2A follows the "strategy" design pattern to enable integration of various [[PlayGo Feature List#Play-out_strategies|strategies]]. [[PlayGo Demos#Play-Out|Watch a Play-Out demo]]
 == Debugging  ==

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 During play-out the system model objects are "linked" to the real application objects, thus showing real runtime values of object's properties.
-PlayGo provides various ways for creating the system model: manually create a new system model from the system model view, import the system model from an existing running application and import the system model from a set of LSCs.
+With PlayGo you can create the system model either manually by creating a new system model from the system model view or by importing the system model from a set of LSCs.
 == Additional Information ==
 Additional links and papers on the underlying languages and ideas, as well as on on-going relevant research, can be found on [http://www.wisdom.weizmann.ac.il/~harel David Harel's website]

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 The system model is a centralized view from which one can observe and manage the object instances participating in the LSCs.
-The system model provides details on the classes and instances that participate in the LSCs. It consists of three parts: classes, instances, including details on each (such as its type - the class it represents), and types, which can be used when defining properties of classes and instances (e.g., a state type that may have the values 'ON' and 'OFF').
+The system model provides details on the classes and objects that participate in the LSCs. It consists of three parts: classes, objects, including details on each (such as its type - the class it represents), and types, which can be used when defining properties of classes and objects (e.g., a state type that may have the values 'ON' and 'OFF').
 [[Image:SystemModel.png|800px | System Model]]

← Older revision		Revision as of 07:29, 25 November 2013
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	The overall effect of a chart is to specify a scenario of behavior, consisting of messages flowing between objects and things having to be true along the way.		The overall effect of a chart is to specify a scenario of behavior, consisting of messages flowing between objects and things having to be true along the way.
−
−	~~[[LSC Reference]]~~

	== Play-In ==		== Play-In ==

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 The overall effect of a chart is to specify a scenario of behavior, consisting of messages flowing between objects and things having to be true along the way.
-[[LSCReference]]
+[[LSC Reference]]
 == Play-In ==