C.E. Hewitt. Viewing control structures as patterns of message passing. Technical Report AI MEMO 410, MIT, Decemder 1976.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... a coherent aggregation of autonomous entities, namely agents, that interact together and with the environment in order to achieve their design goals[Fer95, JW95] In contrast with DS, early MAS systems consider only logical distribution of the control among the software components [EHRLR80, Len75, Hew76] However, with advances in network technologies, the physical distribution of the entities becomes inescapable. Within MAS framework, interaction is considered as a fundamental concept just as agent, environment and organisation[Dem95] Several works have contributed in the study of interaction ....

C.E. Hewitt. Viewing control structures as patterns of message passing. Technical Report AI MEMO 410, MIT, Decemder 1976.

.... computation is the oldest having been introduced independently in (Fogel, 1962; Holland, 1962; Rechenberg, 1965; Schwefel, 1965; Rechenberg, 1973; Holland, 1975; Goldberg, 1989) A collection of the seminal papers in the area is available in (Fogel, 1998) Multi agent systems have their origins in (Hewitt, 1977), while tabu search was introduced in (Glover, 1986) Simulated annealing is the youngest method, having been developed in (Kirkpatrick et al. 1983) although traces of simulated annealing can be found in (Metropolis et al. 1953) The focus of this chapter is on design synthesis using ....

Hewitt, C. (1977). Viewing control structures as patterns of message passing. Artificial Intelligence, 8(3):323--374.

....this creates a distinction between active (i.e. those objects which have a body) and passive objects (i.e. those which do not have a body) 51 cf. e.g. the answer statement in POOL2[Ame89, Section 3. 2] 52 This is adopted in many object oriented languages, such as for example actor languages[Hew77, Agh86, Lie87] ABCL 1[YBS86] ConcurrentSmalltalk[YT86] and suggested adaptations of Eiffel to cover concurrent programming[Mey90, Car90, Mey93] 53 This has been adopted in languages such as for example ConcurrentSmalltalk[YT86] Act [KL89] and ofi[Jon93b] 54 Like, for example, with the ....

C. Hewitt. Viewing control structures as patterns of message passing. Journal of Artificial Inteligence, 8(3):323--364, 1977.

....programming, it is tempting to integrate support for these two issues in the object model. Integrating the first issue into the object model leads to the concept of an active object that embodies a concurrent thread of control. This approach is taken to the extreme by actors languages [Hew77, HB77] where every data item is represented by an active object. While being conceptually clean, actors make it difficult to write sequential programs, which limits their applicability in practice. Less radical is the actors like language ABCL [YBS86] in which the behavior of active objects is ....

Carl Hewitt. Viewing control structures as patterns of message passing. Journal of Artificial Intelligence, 8(3):323--364, 1977.

....cooperation, the system of constraints is split into different subsets of constraints according to the capabilities of the available solvers; Each solver manages its own constraint store 3 and has its own solving strategies. The architecture of our system is based upon the concept of agents [Hew77, Agh86] that communicate via asynchronous message passing. Messages propagate failures as well as new derived constraints. Our model is inspired from works on Concurrent Constraint Logic Programming languages (cc) which are based on communication and synchronization by Ask and Tell messages ....

Carl Hewitt. Viewing control structures aspatterns of message passing. Artificial Inteligence, 8, 1977. 18

....part can be examined and altered by the methods in the behavior part. The monitor part is used to achieve synchronization when required. Orient84 K supports multiple inheritance. Mutual execution are realized through changing the interface of the object. 2. 2 Actor Based Languages The actor model [65, 1, 2, 3, 66] is not object oriented as it does not support inheritance or delegation; rather it is more appropriately considered to be object based. However, it may serve as the foundation for an actor based OOP language. An actor is simply an object which responds to messages, but it can only respond to a ....

....new(CarGenerator) # car generator(CarWasher,Random,Scheduler) init CarGenerator. car( 5,0] 1) car( 7,2] 2) car( 13,8] 3) car( 20,15] 4) car( 23,18] 5) car( 25,20] 6) car( 28,23] 7) car( 36,31] 8) car( 42,37] 9) car( 44,39] 10) car( 52,47] 11) car( 54,49] 12) car( 63,58] 13) car([65,60],14) car( 71,66] 15) car( 71,66] 16) car( 73,68] 17) car( 79,74] 18) car( 81,76] 19) car( 85,80] 20) car( 93,88] 21) car( 95,90] 22) car( 96,91] 23) car( 100,95] 24) car( 107,102] 25) car( 116,111] 26) car( 125,120] 27) car( 131,126] 28) car( 135,130] 29) car( 143,138] 30) 7.1 A Car Washer ....

Hewitt C., Viewing Control Structures as Patterns of Message Passing, Journal of Artificial Intelligence, 8(3):323--364, 1977.

....systems listed under the general category are considered general because the architecture or language which they espouse is not targeted towards any particular application domain. They either provide a language with which a system can be constructed (eg AGORA or the family of ACTOR languages [20] [21]) or a shell which the application developer is able to instantiate with the appropriate cooperation and control knowledge (eg MACE and ABE) In the former case the application designer has complete flexibility over the system to be built, but expends a substantial amount of effort imposing the ....

HEWITT,C.E.: "Viewing Control Structures as Patterns of Message Passing", Artificial Intelligence, 8 (3), 1977, pp 323-364.

....to specify and implement knowledge sharing. But the preeminence of inheritance among the majority of OOP languages gave this term a generic meaning. Delegation [Lieberman 86b] is another strategy we discuss as well. Delegation is discussed in the framework of the Actor model of computation [Hewitt 76, Lieberman 81] Other models presenting various knowledge sharing and classification mechanisms include frames languages (e.g. FRL [Roberts Goldstein 77] and KRL [Bobrow Winograd 77] and (parallel) semantic network languages (e.g. NETL [Fahlman 79] We note that there are many different ....

....a greater degree of flexibility. Our main comment is that this inheritance scheme using hard wired links is not suitable for distributed memory models. 3 Delegation The delegation scheme has been proposed in the Act 1 language [Lieberman 81] An object (called an actor in this computation model [Hewitt 76] where the class concept is absent) knows about another object called a proxy. The object will (at runtime) delegate to its proxy the messages that it cannot recognize. This proxy can in turn delegate the message to its own proxy. The proxy will handle the message in place of the initial receiver ....

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Hewitt, C.E., Viewing Control Structures as Patterns of Message Passing, AI Memo, No 410, MIT, Cambridge MA, USA, December 1976.

....a recasting of the problem can no longer be performed automatically. 3 of constraints according to the capabilities of the available solvers. Each solver manages its own constraint store 4 and has its own solving strategies. The architecture of our system is based upon the concept of agents [Hew77, Agh86] that communicate via asynchronous message passing. Messages propagate failures as well as new derived constraints. The underlying model we propose here is inspired from works on Concurrent Constraint Logic Programming languages (cc) which are based on communication and synchronization by ....

Carl Hewitt. Viewing control structures aspatterns of message passing. Artificial Inteligence, 8, 1977.

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