HARIDI, S. et al. Efficient Logic Variables for Distributed Computing. ACM Transactions on Programming Languages and Systems, v. 21, n.3, p.569-626, May 1999.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....calls a cell . In Mozart these, previously opposing concepts, complement each other and are joined in the effective and efficient implementation of Mozart s distributed, global variable store. Mozart as Agent Platform The design of Mozart facilitates agent based programming [11] Mobile objects [6] may be used to implement mobile agents. An interesting agent based warehouse to shop delivery system simulation is available from the demo section of the Mozart Oz web site [5] A large agent based info cities simulation project was launched in February 2000 [7] There is no widely accepted ....

Haridi Seif, Van Roy Peter, Brand Per, Mehl Michael, Scheidhauer Ralf, Smolka Gerd, "Efficient logic variables for distributed computing", ACM Transactions on Programming Languages and Systems, May (1999)

....However, their main contribution may be in their introduction of a simple concept of computation tailored to distributed computing, termed, in recognition of its origin, the logic variable . The value of the logic variable to distributed computing is discussed in more detail by Haridi et al. [Hari 99] There is a growing realisation that computing needs to escape from the sequential von Neumann model. At the time of the Fifth Generation project the main reason for wishing to consider alternatives was one of efficiency. Declarative languages were considered more efficient to program with, ....

S.Haridi, P van Roy, P.Brand, M.Mehl, R.Scheidhauer and G.Smolka. Efficient logic variables for distributed computing. To appear in ACM Trans. on Programming Languages and Systems. http://www.mozart-oz.org/papers/abstract/TOPLAS99.html

....value written to a location. This allows for implementation in a distributed system where it is the responsibility of a location to inform processes suspended waiting its value of that value. Logic Variables and Futures The single assignment variable is often referred to as the logic variable [Hari 99] as the first extensive use of the concept occurred in logic programming. Another form of single assignment variable is the future of parallel functional programming [Hals 85] and concurrent object oriented programming [Lieb 87] a placeholder for a value being computed concurrently which may ....

....language, Janus, in which logic variables had exactly one reader as well as exactly one writer [Sara 90] We propose a model which is less restrictive than this, so multicasting is not lost. We also avoid the introduction of additional constructs such as the cells and procedure references of Oz [Hari 99] which are not describable using logic variables and the logic programming model. So we develop a language which relies heavily on derived forms, but has a direct translation to concurrent logic programming [Shap 89] There are no direct higher order procedures, unlike Oz. A program consists of a ....

S.Haridi, P van Roy, P.Brand, M.Mehl, R.Scheidhauer and G.Smolka. Efficient logic variables for distributed computing. To appear in ACM Trans. on Programming Languages and Systems .

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S. Haridi, P. Van Roy, P. Brand, M. Mehl, R. Scheidhauer, and G. Smolka. Efficient logic variables for distributed computing. ACM Transactions on Programming Languages and Systems, 21(3):569--626, May 1999.

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S. Haridi, P.-V. Roy, P. Brand, M. Mehl, R. Scheidhauer, and G. Smolka. Efficient logic variables for distributed computing. ACM Transactions on Programming Languages and Systems, 21(3):569--626, 1999.

....a functor is used to set up the right active services and to get access to native resources. Further Reading An overview on the design of Distributed Oz is [48] A tutorial account on distributed programming with Mozart is [150] The distributed semantics of logic variables is reported in [47]; the distributed semantics of objects is discussed in [151] More information on functors, dynamic linking, and module managers in Mozart can be found in [37] 9.3 Architecture The concurrent search engine consists of a single manager and several workers. The manager initializes the workers, ....

Seif Haridi, Peter Van Roy, Per Brand, Michael Mehl, Ralf Scheidhauer, and Gert Smolka. Efficient logic variables for distributed computing. ACM Transactions on Programming Languages and Systems, 21(3):569--626, May 1999.

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Seif Haridi, Peter Van Roy, Per Brand, Michael Mehl, Ralf Scheidhauer, and Gert Smolka. Efficient logic variables for distributed computing. ACM Transactions on Programming Languages and Systems, 21(3), May 1999. 17

....Figure 2, statements are denoted by hSi and hGi, space operations by hSpacei (see Figure 4) and logic variables by italic capitals such as X and Y . The variable P references a procedure and the variable C references a cell. The semantics of the kernel language are given in [70] 64] 86] and [25]. Some syntactic sugar is added to Figure 2 to make it more intuitive. In particular, Figure 2 includes four redundant statements: local, if, case, and dis. The local, if, and case statements can all be expressed with cond. The dis statement can be programmed with cond and computation spaces. The ....

....within method definitions. It allows a simple debugging model and it makes it easy to add exception handling to the language. The current Oz language, Oz 3, conservatively extends Oz 2 with support for a firstclass module concept, called functor [20] and for open, robust, distributed programming [26, 85, 25, 83, 73]. Distribution is transparent, i.e. the language semantics is unchanged independent of how the program is distributed. With respect to logic programming, the distributed extension has two properties: ffl The top level space is efficiently distributed over multiple processes. In particular, the ....

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Seif Haridi, Peter Van Roy, Per Brand, Michael Mehl, Ralf Scheidhauer, and Gert Smolka. Efficient logic variables for distributed computing. ACM Transactions on Programming Languages and Systems, 21(3):569--626, May 1999.

....in which the declaration occurs. This is important because Oz is fully compositional (all statements can be nested) Oz has syntactic support to make the explicit declarations less verbose. 2. 1 The Browser Here s one way to execute Append and display the result: declare A in Append [1 2 3] [4 5 6] A Browse A which can also be written as follows: Browse Append [1 2 3] 4 5 6] This uses the same syntactic short cut as the definition of Append. Note that elements of Oz lists are not separated by commas as in Prolog. This code displays the output of Append in the Browser, a graphic ....

....(all statements can be nested) Oz has syntactic support to make the explicit declarations less verbose. 2. 1 The Browser Here s one way to execute Append and display the result: declare A in Append [1 2 3] 4 5 6] A Browse A which can also be written as follows: Browse Append [1 2 3] [4 5 6] This uses the same syntactic short cut as the definition of Append. Note that elements of Oz lists are not separated by commas as in Prolog. This code displays the output of Append in the Browser, a graphic tool for examining data structures and observing their evolution [10] The Browser is ....

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Seif Haridi, Peter Van Roy, Per Brand, Michael Mehl, Ralf Scheidhauer, and Gert Smolka. Efficient logic variables for distributed computing. ACM Transactions on Programming Languages and Systems, 2000. To appear.

....means that concurrent programming becomes very easy. For example, synchronizing on data availability is completely invisible. This is one of the most common concurrent operations. Because of dataflow synchronization, many concurrent and distributed programming idioms become very simple [3]. They are also efficient. For example, we have measured a producer consumer example that generates a stream of 1000000 integers and sums them [1] This does asynchronous FIFO communication between the producer and consumer. We compared Java 2 (JDK 1.2) with Mozart 1.0.1 on an UltraSPARC 2 running ....

....ticket. Show E2 10000 Call function In addition to records and functions, the ticket can also be used to pass unbound variables. Such variables can be bound to exactly one value. Any operation that needs the value will wait; this is how Mozart does dataflow synchronization [3]. The first process creates the variable and makes it globally accessible: declare X Show Connection.offerUnlimited X But the process does not bind the variable yet. Other processes can get a reference to the variable: declare X= Connection.take . X s ticket. Browse X Unlike ....

Seif Haridi, Peter Van Roy, Per Brand, Michael Mehl, Ralf Scheidhauer, and Gert Smolka. Efficient logic variables for distributed computing. ACM Transactions on Programming Languages and Systems, May 1999.

....mean entities that do not change over time. These entities are replicated, and the incidence of both the locality scalability and fault tolerance properties on them is minor. 2. Single assignment entities: these are logic variables. The binding process is done by a distributed unification protocol [5], that implements their distributed semantics. The incidence of the locality scalability and fault tolerance properties on them is of medium importance. 3. Statefull entities: these are cells, objects and threads. Threads reduction statements are done at the thread home site. A cell is a mutable ....

Seif Haridi, Peter Van Roy, Per Brand, Michael Mehl, Ralf Scheidhauer, and Gert Smolka. Efficient logic variables for distributed computing. TOPLAS, To appear.

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HARIDI, S. et al. Efficient Logic Variables for Distributed Computing. ACM Transactions on Programming Languages and Systems, v. 21, n.3, p.569-626, May 1999.

No context found.

S. Haridi, P. Van Roy, P. Brand, M. Mehl, R. Scheidhauer, and G. Smolka, "Efficient logic variables for distributed computing", ACM Transactions on Programming Languages and Systems, 21(3), May 1999.

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