A. Yonezawa, ABCL: An object-oriented concurrent system: MIT Press, 90.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....original programs. Assume the annotation for latency hiding has the following form. This annotated expression is interpreted as follows. Before evaluation of the expression e, the expression e a is evaluated. When e a is a synchronous method invocation form (i.e. present type messages in ABCM[130]) it is executed as an asynchronous (i.e. future type) one. When the method invocation form that has the same method name and parameters values to e a appears during the subsequent evaluation of e, it performs the touch operation to the reply box that is generated by the asynchronous invocation ....

Akinori Yonezawa, editor. ABCL: An Object-Oriented Concurrent System. MIT Press, Cambridge, MA, 1990. 136

....via message passing. The predominant approach to concurrent object based systems is that of the actor model of computation [17, 1] This model has not only been implemented directly [19] but has also been used as the basis for combining objects and concurrency in other languages, such as ABCL [27] and Concurrent Prolog [24, 18] The metaphor used in the actor model is of a mail system, with messages being addressed and sent directly to individual actors. Thus, actor systems are based upon point to point message passing and message driven computation. Concurrent METATEM is based on a ....

A. Yonezawa, editor. ABCL: An Object-Oriented Concurrent System. MIT Press, 1990.

....representation of objects is xed. In a similar way, stubs, which are designated as remote, can be dynamically sent to a farmer module, the client, thus aiding in con guration of the data farm pipeline. These re ection facilities have previously been available only in actor systems, e.g. ABCL [ 39 ] and Merle IV [ 40 ] designed before the onset of mobile stations. In e ect, re ectance is a form of code reuse or inheritance for dynamic systems. 5 Code generation Code generators (CG) 41 ] enable application code to be entered in a schematic manner in a graphical format. 42 ] for Linda ....

A. Yonezawa, editor. ABCL: An Object-oriented Concurrent System. MIT, Cambridge, MA, 1990.

....object. For instance some methods may need to be executed in mu tual exclusion or may need to be ordered to ensure the coherence of some instance variables. This level is similar to the meta level of reflective languages and metaobject protocols (e.g. Open C [9] ACT [16] CLOS [6] or ABCL R [27]) An object state is a mapping from the set of instance variables to a set of values. A transition between two object states is associated with a synchronized method. A group behavior factorizes several object behaviors. So the object model is a particular refinement of the group level. In a ....

A. Yonezawa. ABCL: An Object-Oriented Concurrent System. Computer Systems Series. MIT Press, 1990.

....schemes can be derived from classical concurrent programming, and a general distinction can still be made depending on whether synchronization specifications are centralized or not. Such constructs, however, suffer from several characterizing drawbacks; e.g. the inheritance anomaly [8] and the so called code tangling problem [9] Solutions to the former problem have been proposed by [10] 11] and [12] whereas the latter could be faced by adopting an approach that separates synchronization issues from operational issues, according to the proposal of [9] We decided to ....

A. Yonezawa, "ABCL: An Object-Oriented Concurrent System", 1990.

.... development of Java based environment, distributed and mobile computation seems to emerge as the leading edge of computing (for example, see [BC96, Car96, Car95a, Wad97] Concurrent objects provide an interesting basis for the use of this emerging type of computation (for example, see [Ame89, Yon90, Car95b] 1 Yet, uniform behavior concurrent objects (i.e. a direct extension of sequential objects in which objects have an eternal life time and a constant interface) lack some essential features to model some parts of this type of computation. Objects with changing interfaces (non uniform ....

A. Yonezawa. ABCL: An Object-Oriented Concurrent System. MIT Press, 1990. 10

....libraries which implement the Actor model of computation have been developed in di erent object oriented languages. Three examples of these frameworks are the Actor Foundry [29] Actalk [7] and Broadway [33] Several actor languages have also been proposed and implemented to date, including ABCL [39], Concurrent Aggregates [12] Rosette [34] and Thal [25] There are several advantages associated with directly using an actor programming language, as compared to using a library for actors: Semantic constraints: Certain semantic properties can be guaranteed at the language level. For ....

....a thread manipulating that state is more appropriate than a passive object oriented programming language (even with an actor library) for implementing concurrent and distributed systems to be executed on the Internet. The ABCL family of languages has been developed by Yonezawa s research group [39] to explore an object oriented concurrent model of computation, based on Actors. ABCL has been developed in Common Lisp. One signi cant di erence is that the order of messages from one object to another is preserved in their model. There are also three types of message passing mechanisms: past, ....

A. Yonezawa, editor. ABCL An Object-Oriented Concurrent System. MIT Press, Cambridge, Mass.,

....The object level describes the behavior of a member object of the group. It gives the synchronization policy for the object methods. This level is similar to the meta level of reflective languages and meta object protocols (e.g. Open C [Chi95] Act [KL89] CLOS [BDB 88] or ABCL R [WY88, Yon90] The object level behavior is defined with a state transition automaton. As we need to consider intra object parallelism its semantics, that is presented in [SDF96] differs from the usual semantics of finite state automata theory. Finally the method level describes the algorithmic structures ....

A. Yonezawa. ABCL: An Object-Oriented Concurrent System. Computer Systems

....code that each class inherits from its superclass. Most of existing COOLs allow concurrency among different objects only (interobjects concurrency) Examples of such languages are CEIFFEL [13] POOL I [14,15] Eiffel [16] C [17] ConcurrentSmalltalk 90 [18] Hybrid [19] and ABCL [20]. Conversely, CJava exploits concurrency even within a single object (intra object concurrency) Each CJava concurrent object may answer to several messages in parallel. This greatly increases parallelism in CJava applications. The ability of separately reusing a method s implementation and the ....

A. Yonezawa, ABCL: an Object-Oriented Concurrent System. MIT Press., 1990.

.... a key distinction between them is that organizations usually have got a key motivation for their very existence 2 cf. Matsuda (1992) and Steiner et al. 1990) 3 cf. O Hare and Jennings (1994) 4 cf. Bond and Gasser (1988) 5 cf. Hern (1988) 6 cf. Shoman (1993) 7 cf. Masini et al. 1991) and Yonezawa (1990). 7 (e.g. maximizing profit) Consequently these organizations exhibit a clearly defined framework within which departments and workgroups have to operate, and they provide a strict portfolio of services with an associated set of business procedures. In current multi agent systems such ....

Yonezawa, A., (ed.): ABCL An Object-Oriented Concurrent System, MIT Press, Cambridge, Mass., 1990.

....of computations into parallel subcomputations, while the compiler choses which decompositions to ignore, and keeps track of data and control dependences to generate parallel tasks from the chosen decompositions. Fine grained concurrent languages, such as Concurrent Aggregates [28, 29] and ABCL [30] also fall in this category. 7. Finally, domain specific packages allow the users to specify their problems, and possibly select solution strategies from the system s repertoire. These are also as high in the hierarchy as the automatic parallelizing compilers. However, they are obviously not ....

Akinori Yonezawa. ABCL: an object oriented concurrent system. The MIT Press, 1990.

....language optimizing compiler Figure 1: Types of implicit programming: a) traditional implicit programming; b) expose and then reduce implicit programming. OOP provides a natural approach to parallel programming in which objects are considered as concurrency units, to be executed in parallel (Yonezawa 1990). Consequently, many concurrent object oriented programming (COOP) languages have been developed in recent years, most of them derived either from models of sequential languages, such as C and SMALLTALK, or from the Actor model (Agha 1986) All COOP languages comprise an extension of these ....

....is computed and sent back from the get value method and not from the eval method, two additional instance variables must be used. The father variable saves the address of the sender object to which the reply value should be sent. The value variable is used to accumulate the reply values. The ABCL (Yonezawa 1990) version is based on future type messages that is an extension to the basic Actor model. Every asynchronous message is associated with a special future object that is created explicitly to save its reply value. The execution of the current eval method is suspended, by a special built in ....

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Yonezawa, A. (1990) ABCL: An Object-Oriented Concurrent System. MIT Press, Boston, MA.

....models and programming languages based on the actor concept. These extensions use inheritance to re ne the semantics of the Actalk kernel. For example, we simulate Agha s Actor computation model through the class AghaActorBehavior as a subclass of ActorBehavior. We also simulate Yonezawa s Abcl 1 [11] language constructs through the class AbclActor subclass of Actor. This shows the merits of modularity for our kernel. Because the kernel and its extensions are related by inheritance, one could easily compare them. Inheritance helps not only to classify various actor models, but also to clearly ....

Yonezawa A., ABCL: An Object-Oriented Concurrent System, Series in Computer Science, MIT Press, Cambridge MA, USA, 1990. 10

....buffer. When the buffer is empty the out method is inapplicable and its execution due to a request message can be delayed by an explicit test in the method itself. While this is a plausible solution it introduces a problem called the Inheritence Anomaly [ Matsuoka et al. 90, America 87, Briot and Yonezawa 90, Kafura and Lee 89 ] Due to the anomaly, when the Bounded Buffer class is subclassed, problems arise due to the state dependent synchronization code in the body of out one has to provide a complete redefinition of the out method in the subclass. This renders the out method in the superclass ....

Yonezawa, A., (ed), ABCL: An Object-Oriented Concurrent System, MIT Press, Cambridge, MA, 1990.

....first described by Hewitt [82] and then further developed by Agha [2] Actors are concurrent objects which communicate with each other via messages. Actors execute in response to messages, and each actor object may contain several concurrently executing tasks. Actor based languages include ABCL [145], Cantor [11] and Charm [90] Implementations of actor languages require complicated compilation strategies and sophisticated run time support libraries, such as the Concert system [91] for fine grain object management. Because of this complexity, we have not based the LPARX run time system on ....

A. Yonezawa, ABCL: An Object Oriented Concurrent System, MIT Press, 1990.

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A. Yonezawa, ABCL: An object-oriented concurrent system: MIT Press, 90.

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Akinori Yonezawa, editor. ABCL: An Object-Oriented Concurrent System. MIT Press, 1990. ISBN 0-262-24029-7.

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A. Yonezawa, editor. ABCL An Object-Oriented Concurrent System. MIT Press, Cambridge, Mass., 1990.

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A. Yonezawa, editor. ABCL An Object-Oriented Concurrent System, chapter Re ection in an ObjectOriented Concurrent Language, pages 45-70. MIT Press, Cambridge, Mass., 1990.

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A. Yonezawa, editor. ABCL An Object-Oriented Concurrent System. MIT Press, Cambridge, Mass., 1990.

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Akinori Yonezawa. ABCL: An Object-Oriented Concurrent System. MIT Press, 1990.

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Yonezawa, A., ed. (1990), ABCL: An Object-Oriented Concurrent System, The MIT Press, Cambridge, Mass., USA.

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Yonezawa, A., (ed.), ABCL: An Object-Oriented Concurrent System, MIT Press, Cambridge, Mass., 1990.

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Yonezawa A. (ed), ABCL : An Object-Oriented Concurrent System, MIT Press, 1990.

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Akinori Yonezawa, editor. ABCL: An Object-Oriented Concurrent System. Computer Systems Series. MIT Press, 1990.

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