Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, SE-11(1):43--59, January 1985.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Extensions to the work, such as anycast [143] provide more e#cient resource location mechanisms but do not support selection of services based on other attributes. As with other distributed object systems, the focus in the DISCWorld ORB system is on LAN based location rather than network topology [2, 77]. The information flow throughout the directory system is shown in Figure 22. Part (i) of Figure 22 shows a single registry domain consisting of two base level registries and a single primary registry. When a server registers or deregisters at a base level registry, the registration information ....

Guy T. Almes, Andrew P. Black, Edward D. Lazowska and Jerre D. Noe. The Eden system: A technical review. IEEE Transactions on Software Engineering, Volume SE-11, Number 1, pages 43--59, January 1985.

....object sharing among remote users. Although remote objects are reactive, two objects on different hosts may not share the same class (since classes and instances must be co resident) Distributed Smalltalk does not support persistent objects. There is no mechanism analogous to the Eden checkpoint [Almes 85] that snapshots the active state of an object into a passive, long lived representation, although such a mechanism could be readily developed. 10 ffl Smalltalk is a powerful programming environment that provides careless users with enough flexibility to shoot themselves in the foot. ....

....methodology has also been applied to more tightly coupled multiprocessor systems. Examples of such systems include Sloop [Lucco 87] and Presto [Bershad 87] In this section we will examine several of these systems including Eden, Argus, Sloop, and Emerald. 27 Eden Eden [Lazowska 81, Almes 85, Black 85] was a distributed, object oriented operating system developed at the University of Washington over the five year period 1980 1985. One of Eden s design goals was to support a logically integrated computer system on a physically distributed hardware base, thus providing a midpoint in ....

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Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, SE-11(1):43--59, January 1985.

....capable of specifying a system object, but there are several cases where the language object model differs from the system object. For example, one language may not provide any object oriented support. In such a system, the user must be conscious of a system object that is coarse grained. Eden [Almes et al. 85] Argus [Liskov 88] and Clouds [Dasgupta 86] Wilkenloh et al. 89] can be classified into this type, which we call the different object single language model. System Objects Space Language Space system object procedures, functions, objects, etc. Figure 2.1 Different Object Single Language ....

....by using user defined primitives [PP 89] in Smalltalk 80 context. Proxy in our framework is applicable to a multi language environment shown in Figure 3.2. We do not define how proxy should be implemented, but an approach similar to that in Distributed Smalltalk or the bridge object in Eden [Almes et al. 85] is possible. proxy object Language Objects Space System Objects Space Figure 3.2 Proxy (multi language environment) 3.2 Export Previously, we laid down the requirement that any user should be able to describe a system object using that user s favorite language. To achieve such a ....

Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, Vol. SE-11, No. 1, pp.43--59, January 1985.

....and good performance. GC algorithms found in the literature are not adequate for a cached distributed shared store such as Larchant (see Chapter 2 for more details) This is due to the fact that Larchant is different from most other systems with the same overall goal (support for sharing) [2, 66, 96, 110, 114] because it extends caching with PBR. In particular, the coherence interference problem, and the issue of safety in presence of replicated data, possibly incoherent, were never addressed before. 1.2 Thesis Main Contributions This thesis contains three main contributions. The first one is a ....

....OODBs are limited by their client server architectures: no fine grained client to client transfers. In addition they do not support large scale sharing. 3.2. 3 RPC based Systems Remote Procedure Call (RPC) 17] is a basic communication mechanism that forms the basis for the client server model [2, 66, 110, 114]. RPC solves the problems of identification and remote access. However, every remote data access is burdened with communication to the server, which becomes a performance and availability bottleneck. This makes the client server architecture inadequate for interactive CAD and cooperative ....

Guy Almes, Andrew Black, Edward Lazowska, and Jerry Noe. The Eden system: a technical review. IEEE Transactions on Software Engineering, SE-11(1), January 1985.

....when it was introduced, but added Insiders, however, know that under the covers of every AS 400 lurks a System 38 . Discussion here is therefore limited to the System 38, except to note that the AS 400 is the only commercially successful capability based system. 2.4. 6 Eden Eden [LLA 81, ABLN85] is an object based system. Objects in Eden are called ejects. Each eject has a unique identifier. Ejects communicate with each other using invocation. The ability to invoke an eject is conferred by capabilities. Each capability has the id of the target eject and a set of access rights. The list ....

G.T. Almes, A.P. Black, E.D. Lazowska, and J.D. Noe. The Eden system: a technical review. IEEE Transactions on Software Engineering, SE-11(1):43--59, January 1985.

....in secondary storage. Argus does not free the programmer from worrying about the details of concurrency. The programmer must think about deadlocks and starvation and implement the code to avoid them when possible. Moreover, there is no notion of classes and inheritance in Argus. 1.4. 4 Eden Eden[1] is a system and a programming language developed to build distributed object based applications. Eden supports the static variation of the active object model. Each Eden object or Eject has a long term state that contains the persistent information, a short term state that contains the volatile ....

Almes, G., Black, A., Lazowska, E., and Noe, J. The Eden system: A technical review. IEEE Transactions on Software Engineering 11, 1 (Jan 1985).

....Many research projects have explored operating systems issues within the context of programming languages. For example, Argus [33] and Clouds [16] explored the use of transactions within distributed programming languages. Other important systems that studied issues of distribution include Eden [3], Emerald [11] and Amber [12] These systems explored the concepts underlying object migration, but did not investigate resource management. Language based operating systems have existed for many years. Most of them were not designed to protect against malicious users, although a number of them ....

G. T. Almes, A. P. Black, E. D. Lazowska, and J. D. Noe. The Eden system: A technical review. IEEE Transactions on Software Engineering, SE-11(1):43--59, Jan. 1985.

....Emerald also demonstrates that the object based model of programming can be incorporated both elegantly and efficiently in distributed systems. Emerald draws heavily upon the experience gained from Smalltalk [GR83] the Argus Language and System [Lis84] and, in particular, the Eden system [ABLN85, Bla85a] and the Eden Programming Language (EPL) Bla85b] Featuring an object oriented style of programming, Emerald presents a unified semantic view of objects appropriate for private, local, data only objects as well as shared, remote, concurrently executing objects. The nature of objects in ....

Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, SE-11(1):43--59, January 1985.

....orientation and dependency layering. The relationship between these traditionally disjoint methods of decomposition is considered here. The virtues of object orientation are so well known that they need no repeating. Although kernel support for user objects has been well covered, such as Eden [2] and Argus [11] the use of O O for OS implementation has received little attention. Chorus [13] and Spring [9] are composed of objects internally (C ) but internal object orientation is not exposed nor exploited. The most extensive use of O O in OS implementation is Choices [4] which ....

G. T. Almes, A. P. Black, E. D. Lazowska, J. D. Noe, The Eden System: A Technical Review, IEEE Transactions on Software Engineering, Jan 1985.

....language level mechanisms. In Argus which is an object based language for distributed programming, the support for object management is entirely at the language level [Liskov 1988] Eden provided operating system level support for object naming, protection, and network transparent access [Almes et al. 1985]. Support for new object definitions and synchronization of concurrent operations on objects was supported at the language level. Amoeba associates with each object a server process; an object is accessed through a capability, which contains the address for a communication port of the server ....

G. T. Almes, A. P. Black, E. D. Lazowska, and J. D. Noe. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, SE-11:43--59, January 1985.

....prepare for the next state. This adds an extra degree of complexity; the straightforward control flow of fig. 1.1 must be systematically transformed. In an application where there is little control flow, such as a drawing procedure rubber(players playerArray[4] returns integer array gamesWon[2] of integer; do contract : 0; declarer : 0; leader : 0; array game[13] 4] of card; for player : 0 to 3 do playerArray[player] deal(cards) od do get the next player s bid if the bid is higher than contract then contract : the new bid declarer : the current bidder leader : the current bidder ....

....will also examine Sun Microsystem s Java, which promises to have significant impact, despite its novelty. When development first started on Dreme, the only significant languages explicitly supporting physical mobility of objects in a network were Emerald [50, 41, 28] and, to a lesser extent, Eden [2, 6], which we will examine first. A number of systems have come into existence contemporaneously with Dreme. Excluding Telescript [26] about which so little is known, the most sophisticated, and the most similar to Dreme is Obliq [10, 9] an object oriented language which also uses lexical scoping ....

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G. T. Almes et al. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, 11(1):43--58, 1985.

....sharing. Although remote objects are reactive, two objects on different hosts may not have the same class (since classes and instances must be co resident) Distributed Smalltalk does not provide an object server for persistent objects. There is no mechanism analogous to the Eden checkpoint [Almes et al. 85] that snapshots the active state of an object into a passive, long lived representation. Such a mechanism is not found in current Smalltalk implementations, but would be useful in Distributed Smalltalk. ffl Smalltalk is a powerful programming environment that provides users with enough ....

....ffl Vegdahl identified some of the difficulties associated with moving object structures between Smalltalk systems [Vegdahl 86] Distributed Smalltalk uses techniques similar to his to handle complex structures. ffl Distributed Smalltalk shares many historical and philosophical roots with Eden [Almes et al. 85] and Emerald [Black et al. 86] Local experience with these systems provided the yeast for many of the ideas presented here. 5.3 Future Research Directions Distributed Smalltalk provides fertile ground for further research in several areas: ffl There is considerable room for improving the ....

Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, SE-11(1):43--59, January 1985.

....of milliseconds to be invoked. Small data objects are virtually costless and invocations are achieved in tenths of microseconds. One can say that a gap of thousand times both in resources and CPU timing dissociates both types of objects. As both types of objects are useful, systems such as Eden [Almes 85, Black 85] and Argus [Liskov 87] support both, but require different definition mechanisms for each type of objects. The Emerald [Black 86, Jul 87] system manages to hide objects dissimilarities from the programmer offering a single program paradigm. Although lightweight entities, data objects ....

Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, SE-11(1):43--58, January 1985.

....space and support for local invocation. References: 51, 52] 5.3 Emerald Emerald is an object oriented language and run time system (kernel) developed at the University of Washington. It combines the uniform object model of Smalltalk [53] with the distributed object model presented by Eden [54, 55]. Two major design goals were the provision of object mobility and the treatment at the language level of all objects within the system in a uniform manner. Implementations are reported for VAX, HP 9000 300, Sun 3 and Sun SPARC machines, running on top of UNIX 4.2 BSD and compatible versions ....

G. T. Almes, A. P. Black, E. D. Lazowska, and J. D. Noe. The Eden system: A technical review. IEEE Transactions on Software Engineering, SE-11(1):43--58, January 1985.

....actually implemented. 2 Languages for Distributed Programming Many object oriented programming languages for distributed programming have been designed either as completely new languages or as extensions to existing languages. Early object support operating systems such as Argus [36] and Eden [1] typically mapped every remotely accessible object onto a single process making such objects rather heavyweight when compared to the fine grained objects supported by conventional object oriented programming languages. The result was that the supported programming languages the Argus ....

Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden system: A technical review. IEEE Transactions on Software Engineering, SE-11(1):43--58, January 1985.

....is necessary to define a generic architecture that supports a large spectrum of existing object oriented models. Existing distributed objectoriented systems can be roughly divided in two trends: 1. Systems that do not provide a uniform object model, such as Argus [19, 20, 21] Clouds V2 [14] Eden [3, 11, 18], Hermes [12] and SOS [24, 25, 26] 2. Systems that do provide a uniform object model, such as Amber [13] Emerald [9, 10, 16] and Guide [7, 8, 17] Systems with a non uniform object model are typically designed for specialized distributed applications with, for example, strong requirements in ....

Guy Almes, Andrew Black, Edward Lazowska, and Jerry Noe. The Eden system: a technical review. IEEE Transactions on Software Engineering, SE-11(1), January 1985.

....consistent system state into another consistent system state, regardless of concurrent executions of other transactions and crashes. Despite the recognition given to the concept, however, OS researchers have refrained from adopting transactions in practice. Some exceptions such as Argus [10] Eden [1], and Clouds [6] only prove the rule. The main advantage of programs encapsulated in transactions is their simple structure. Such programs do not have to deal with interleaving of other concurrent programs or worry about system crashes. In other words, the programmer can concentrate on the program ....

G.T. Almes, A.P. Black, E.D. Lazowska, and J.D. Noe. The Eden system: A technical review. IEEE Transactions on Software Engineering, SE-11(1):43--58, January 1985.

....fast access to server data is generalized in Porc by the use of read only methods, which let clients access server data directly without the need for RPC calls. Object based RPC has been used in numerous operating systems and distributed programming systems. Systems such as Hydra[Wulf 74] Eden[Almes et al. 85] Clouds[Allchin McKendry 83] and Choices[Dave et al. 92] have all built object support into the operating system kernel. Objects are protected from each other with hardware protection boundaries. In Eden and Clouds, objects are represented as separate address spaces making them inappropriate ....

G. T. Almes, A. P. Black, E. D. Lazowska, and J. D. Noe. The Eden system: A technical review. IEEE Transactions on Software Engineering, SE11 (1):43--59, January 1985.

....checkpoints must be coordinated in order to be able to recover the system. Some systems have used ad hoc rules to determine when to checkpoint each process, effectively causing each process to checkpoint each time it communicates with another process. Examples of these systems include Eden [Almes85, Lazowska81] and the Tandem NonStop system [Bartlett81, Dimmer85] These systems force processes 12 to checkpoint frequently, creating a large overhead for the provision of fault tolerance, as has been recognized in these two systems [Black85, Bartlett87] A different style of using checkpointing alone is ....

Guy T. Almes, Andrew P. Black, and Edward D. Lazowska. The Eden system: A technical review. IEEE Transactions on Software Engineering, SE-11(1):43--59, January 1985.

....Emerald also demonstrates that the object based model of programming can be incorporated both elegantly and efficiently in distributed systems. Emerald draws heavily upon the experience gained from Smalltalk [GR83] the Argus Language and System [Lis84] and, in particular, the Eden system [ABLN85, Bla85a] and the Eden Programming Language (EPL) Bla85b] Featuring an object oriented style of programming, Emerald presents a unified semantic view of objects appropriate for private, local, data only objects as well as shared, remote, concurrently executing objects. The nature of objects in ....

Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, SE-11(1):43--59, January 1985.

....considerations, language design for distributed systems is strongly influenced by the underlying distributed operating system. Consequently, Emerald draws heavily upon the experience gained from Smalltalk [Goldberg 83] the Argus Language and System [Liskov 84] and, in particular, the Eden system [Almes 85, Black 85a] and the Eden Programming Language (EPL) Black 85b] Featuring an object oriented style of programming, Emerald presents a unified semantic view of objects appropriate for private, local, data only objects as well as shared, remote, concurrently executing objects. The nature of ....

Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, SE-11(1):43--59, January 1985.

....only through messages. This strict model of fully disjoint protection accommodates distribution, is tempting in its simplicity, and is central to both server structured [Young et al. 87, Rozier et al. 88, Mullender Tanenbaum 86, Custer 93] and object oriented [Allchin McKendry 83, Almes et al. 85] systems. However, we believe it is too simplistic and confining for several reasons: ffl Asymmetric trust relationships are common and can be exploited: A might accept inputs (or memory segments) from B even when B does not trust A. For example, a name server could provide read only access to ....

....of these capability based systems without their costs. Our performance and generality are comparable to standard page based systems, but with improved support for sharing. 7. 4 Object Based Operating Systems and Languages Early object based operating systems, such as Hydra [Wulf et al. 75] Eden [Almes et al. 85] and Clouds [Allchin McKendry 83] support operating system objects addressed via capabilities. Objects in Eden and Clouds are coarse grained, meaning that they are implemented as separate virtual address spaces; object encapsulation is enforced by hard protection boundaries. While these ....

Almes, G. T., Black, A. P., Lazowska, E. D., and Noe, J. D. The Eden system: A technical review. IEEE Transactions on Software Engineering, SE-11(1):43--59, January 1985.

....systems typically lie at the ends of a spectrum: object based languages such as Smalltalk [10] and CLU [17] provide small, local, data objects; object based operating systems, like Hydra [25] and Clouds [1] provide large, active objects. Distributed systems such as Argus [16] and Eden [2] that support both kinds of object have a separate object definition mechanism for each. Choosing the right mechanism requires that the programmer know ahead of time all uses to which an object will be put; the alternative is to accept the inefficiency and inconvenience of using the wrong ....

Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, SE-11(1):43--59, January 1985.

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Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden System: A Technical Review. IEEE Transactions on Software Engineering, SE-11(1):43--59, January 1985.

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Guy T. Almes, Andrew P. Black, Edward D. Lazowska, and Jerre D. Noe. The Eden system: a technical review. IEEE Transactions on Software Engineering, SE-11(1):43-59, January 1985.

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