Changes for page Overview

From 4.1 to 3.1

From version 3.1

edited by Andrea Omicini
on 10/08/2021 16:41

Change comment: Document converted from syntax xwiki/1.0 to syntax xwiki/2.1

To version 1.1

edited by Andrea Omicini
on 08/10/2020 00:28

Change comment: Imported from XAR

Raw
Rendered

Summary

Page properties (2 modified, 0 added, 0 removed)

Details

Page properties

Syntax

@@ -1,1 +1,1 @@
--XWiki 2.1
++XWiki 1.0

Content

@@ -1,63 +1,58 @@
--{{include document="Main.MacroSheet"/}}{{include document="ReSpecT.MacroSheet"/}}
++#includeMacros("Main.MacroSheet")
--{{velocity filter="none"}}
--{{html clean="false" wiki="true"}}
--= #respect() Overview =
++1 #respect() Overview
--#respect() (**Re**action **Spec**ification **T**uples) is a logic-based language for the coordination of complex software systems.
++#respect() (*Re*action *Spec*ification *T*uples) is a logic-based language for the coordination of complex software systems.
  ##
  #respect() promotes a coordination model providing tuple centres as programmable, general-purpose coordination media.
  ##
  The behaviour of #respect() tuple centres is programmed through the #respect() first-order logic language.
--== The #respect() Tuple Centre Coordination Model ==
++1.1 The #respect() Tuple Centre Coordination Model
  A tuple centre is a tuple space enhanced with the possibility to program its behaviour in response to interactions.
  ##
--First of all, coordinated entities (//#respect() agents//, henceforth, or simply //agents//) can operate on a #respect() tuple centre in the same way as on a standard Linda tuple space: by exchanging //tuples// &mdash; which are ordered collection of knowledge chunks &mdash; through a simple set of coordination primitive.
++First of all, coordinated entities (~~#respect() agents~~, henceforth, or simply ~~agents~~) can operate on a #respect() tuple centre in the same way as on a standard Linda tuple space: by exchanging ~~tuples~~ &mdash; which are ordered collection of knowledge chunks &mdash; through a simple set of coordination primitive.
  ##
  So, an agent can write a tuple in a tuple centre with an #code("out") primitive; or read a tuple from a tuple centre with primitives such as #code("in"), #code("rd"), #code("inp"), #code("rdp") specifying a tuple template - that is, an identifier for a set of tuples, according to some tuple matching mechanism.
  ##
  Reading tuples can be
--* //destructive// &mdash; #code("in"), #code("inp") remove the matching tuple &mdash; or //non-destructive// &mdash; #code("rd"), #code("rdp") simply read the matching tuple
--* //suspensive// &mdash; #code("in"), #code("rd") wait until a matching tuple is found &mdash; or //non-suspensive// &mdash; #code("inp"), #code("rdp") immediately return either the matching tuple or a failure result
--<p/>
--but is anyway always //non-deterministic//: when more than one tuple in a tuple centre are found that match a tuple template, one is non-deterministically chosen among them and returned.
--<p/>
--Accordingly, a tuple centre enjoys all the many features of a tuple space, which can be classified along three different dimensions:
++* ~~destructive~~ &mdash; #code("in"), #code("inp") remove the matching tuple &mdash; or ~~non-destructive~~ &mdash; #code("rd"), #code("rdp") simply read the matching tuple
++* ~~suspensive~~ &mdash; #code("in"), #code("rd") wait until a matching tuple is found &mdash; or ~~non-suspensive~~ &mdash; #code("inp"), #code("rdp") immediately return either the matching tuple or a failure result
++but is anyway always ~~non-deterministic~~: when more than one tuple in a tuple centre are found that match a tuple template, one is non-deterministically chosen among them and returned.
++Accordingly, a tuple centre enjoys all the many features of a tuple space, which can be classified along three different dimensions:
  * generative communication
  * associative access
  * suspensive semantics
--<p/>
--The main features of //generative communication// (where information generated has an independent life with respect to the generator) are the forms of uncoupling (space, time, name) based on mediated interaction: sender and receiver do not need to know each other, to coexist in the same space or at the same time in order to communicate (to exchange a tuple, in particular), and more generally, to interact.
++
++The main features of ~~generative communication~~ (where information generated has an independent life with respect to the generator) are the forms of uncoupling (space, time, name) based on mediated interaction: sender and receiver do not need to know each other, to coexist in the same space or at the same time in order to communicate (to exchange a tuple, in particular), and more generally, to interact.
  ##
--//Associative access// (access based on structure and content of information exchanged, rather than on location, or on name) based on tuple matching promotes synchronisation based on tuple structure and content: thus, coordination is data-driven, and allows for knowledge-based coordination patterns.
++~~Associative access~~ (access based on structure and content of information exchanged, rather than on location, or on name) based on tuple matching promotes synchronisation based on tuple structure and content: thus, coordination is data-driven, and allows for knowledge-based coordination patterns.
  ##
--Finally, //suspensive semantics// promotes coordination patterns based on knowledge availability, and couples well with incomplete, partial knowledge.
--<p/>
--Even more, while the basic tuple centre model is independent of the type of tuple, #respect() tuple centres adopt logic tuples &mdash; both tuples and tuple templates are essentially Prolog //facts// &mdash; and logic //unification// is used as the tuple-matching mechanism.
++Finally, ~~suspensive semantics~~ promotes coordination patterns based on knowledge availability, and couples well with incomplete, partial knowledge.
++
++Even more, while the basic tuple centre model is independent of the type of tuple, #respect() tuple centres adopt logic tuples &mdash; both tuples and tuple templates are essentially Prolog ~~facts~~ &mdash; and logic ~~unification~~ is used as the tuple-matching mechanism.
  ##
  So, for instance, an agent #code("ag1") performing operation #code("we ? in(activity(ag1,CaseID))") on tuple centre #code("we") containing tuples #code("activity(ag1,c16)") and #code("activity(ag2,c22)") will be returned tuple #code("activity(ag1,c16)") &mdash; the one unifying with the template &mdash; removed from #code("we").
  ##
--Since the overall content of a tuple centre is a multiset of logic facts, it has a twofold interpretation as either a collection of messages, or a (logic) //theory of communication// among agents &mdash; thus promoting in principle forms of //reasoning about communication//.
--<p/>
--Finally, a tuple centre is a programmable tuple space, so as to add //programmability// of the coordination medium as a new dimension of coordination.
++Since the overall content of a tuple centre is a multiset of logic facts, it has a twofold interpretation as either a collection of messages, or a (logic) ~~theory of communication~~ among agents &mdash; thus promoting in principle forms of ~~reasoning about communication~~.
++
++Finally, a tuple centre is a programmable tuple space, so as to add ~~programmability~~ of the coordination medium as a new dimension of coordination.
  ##
  While the behaviour of a tuple space in response to interaction events is fixed &mdash; so, the effects of coordination primitives is fixed &mdash;, the behaviour of a tuple centre can be tailored to the system needs by defining a set of specification tuples, or reactions, which determine how a tuple centre should react to incoming / outgoing events.
  ##
  While the basic tuple centre model is not bound to any specific language to define reactions, #respect() tuple centres are obviously programmed through the #respect() logic-based specification language.
--== #respect() as a Core Coordination Language ==
++1.1 #respect() as a Core Coordination Language
  The original #respect() is a logic-based language for the specification of the behaviour of tuple centre.
  ##
  As a behaviour specification language, #respect():
--
  * enables the definition of computations within a tuple centre, called reactions, and
  * makes it possible to associate reactions to events occurring in a tuple centre.
--<p/>
++
  So, #respect() has both a declarative and a procedural part.
  ##
  As a specification language, it allows events to be declaratively associated to reactions by means of specific logic tuples, called specification tuples, whose form is #code("reaction(E,R)").
@@ -69,7 +69,7 @@
  A reaction as a whole succeeds if all its reaction goals succeed, and fails otherwise.
  ##
  Each reaction is executed sequentially with a transactional semantics: so, a failed reaction has no effect on the state of a logic tuple centre.
--<p/>
++
  All the reactions triggered by an event are executed before serving any other event: so, agents perceive the result of serving the event and executing all the associated reactions altogether as a single transition of the tuple centre state.
  ##
  As a result, the effect of a coordination primitive on a logic tuple centre can be made as complex as needed by the coordination requirements of a system.
@@ -77,12 +77,10 @@
  Generally speaking, since #respect() has been shown to be Turing-equivalent, any computable coordination law could be in principle encapsulated into a #respect() tuple centre.
  ##
  This is why #respect() can be assumed as a general-purpose core language for coordination: a language that could then be used to represent and enact policies and rules for coordination systems of any sort.
--<p/>
--Adopting the declarative interpretation of logic tuples, a #respect() tuple centre has then a twofold nature a //theory of communication// (the set of the ordinary tuples) and a //theory of coordination// (the set of the specification tuples).
++
++Adopting the declarative interpretation of logic tuples, a #respect() tuple centre has then a twofold nature a ~~theory of communication~~ (the set of the ordinary tuples) and a ~~theory of coordination~~ (the set of the specification tuples).
  ##
  In principle, this allows intelligent agents to reason about the state of collaboration activities, and to possibly affect their dynamics.
  ##
  Furthermore, the twofold interpretation (either declarative or procedural) of #respect() specification tuples allows knowledge and control to be represented uniformly (as Prolog-like facts) and encapsulated within the same coordination artefact.
--{{/html}}
--{{/velocity}}