J. Elliot B. Moss. Nested transactions: an approach to reliable distributed computing. Ph.D. thesis, Massachusetts Institute of Technology, 1981. Available as Technical Report MIT/LCS/TR-260.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....computing systems is maintaining data integrity in the presence of concurrency and failures. Atomic transactions, or actions, are a widely accepted solution to these two problems; they are serializable and recoverable, thus hiding concurrency and failures. Nested transactions ( Reed 1978, Moss 1981, Liskov Scheifler 1983] are a generalization of the model of atomic transactions. Nested transactions, or subactions, provide a uniform mechanism for coping with failures and obtaining concurrency within an action. Execution of actions in a nested action model is synchronized in a manner ....

....Bjork 1973] The first detailed design for a model that uses nested atomic actions was developed by Reed ( Reed 1978] Reed proposed a multi version, timestamp based algorithm to ensure serialization of concurrent actions. A locking based model of a nested atomic action system was developed by Moss ( Moss 1981]) Several research projects have designed and implemented a nested atomic action system: Argus ( Liskov Scheifler 1983] uses Moss s model with small modifications (e.g. no distinction between lock holding and lock retaining) The Camelot project ( Spector, et al. 1987] uses a model of ....

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J. Elliot B. Moss. Nested transactions: an approach to reliable distributed computing. Ph.D. thesis, Massachusetts Institute of Technology, 1981. Available as Technical Report MIT/LCS/TR-260.

....have already been explored [Daynbs 95, Daynbs and Gruber 94, Atldnson et al. 96] Only preliminary studies of their performance in real applications have been undertaken so far. Because of the recursive structure of computations in a modem language like Java, some form of nested transaction [Moss 81, H mder and Rotherme193] will be required as a result of program composition and calls of code that contain transactions. There is, however, a choice of nested transaction semantics, for example: the effects of inner transactions may be propagated to parents and only made durable when the top ....

J.E.B. Moss. Nested Transactions: An Approach to Reliable Distributed Computing. PhD thesis, Massachussets Institute of Technology, April 1981.

....control provided little implementation advice for general applications, and early work on transactions, though influenced by Davies, was much less ambitious in its goals. 7 Basic transaction systems do not allow for subtransactions or support concurrency within a transaction. Nested transactions [Moss 1981] extend the flat transaction model by providing the independent failure property for subtransactions, and supporting competitive concurrency within a containing transaction. A number of generalized transaction models have been developed recently in order to overcome some of the limitations of ....

J.E.B. Moss, "Nested Transactions: An Approach to Reliable Distributed Computing," Ph.D. Thesis (Tech. Report 260), MIT Lab. for Computer Science, Cambridge, MA., 1981.

....; s) df (8C) 8t)C(t; t; s) s) transConf lict(t serializable(s) df (8t) do(Commit(t) s ) s oe :transConf lict Theorem 7 (Isolation) Suppose D is a relational theory. Then D j= legal(s) oe serializable(s) 5 Closed Nested Transactions Nested transactions ([17]) are the best known example of ATMs. A nested transaction is a set of transactions (called subtransactions) forming a tree structure, meaning that any given transaction, the parent, may spawn a subtransaction, the child, nested in it. A child commits only if its parent has committed. If a parent ....

J. Moss. Nested Transactions: An Approachto Reliable Distributed Computing. Information Systems Series. The MIT Press, Cambridge, MA, 1985.

....in Venezuela 2 A. Doucet, S. Gancarski, C. Le on, M. Rukoz data in a multidatabase environment. In this approach, when a transaction is sent to a local database, a set of related transactions should be scheduled by the system in order to preserve consistency. Since they were proposed by Moss [13], nested transactions (NT) have been the subject of many studies. Research prototypes [5, 14] and products such as Versant [3] and Encina [1] supporting nested transactions have been developed. However, few works address the issue of integrity constraint checking in the context of nested ....

....[17] 2. We use a nested transactions model where only leaf transactions can perform updates. Each leaf is totally executed on a single site and only accesses objects on that site. This allows to simplify the constraint checking process and does not decrease the expressiviness of the model (see [13]) The assignment of the sub transactions of a NT to the different sites is induced by the localization of the objects in the network. When a global transaction is initiated on a site, its sub transactions are recursively initiated on the same site, until a sub tree containing leaves that are all ....

J. E. B. Moss. Nested Transactions: An Approach to Reliable Distributed Computing. MIT Press, Cambridge, MA, 1985.

....single new object whose state correctly reflects the combination of those updates. Reconciliation complexity ranges from very simple to extremely complex. The complexity of reconciliation is partly determined by the object operation s execution model. We assume the closed nested transaction model [7] is applied to method invocations on objects. This research was partially supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada under Operating Grant OGP 0105566. 1 2 The Execution Model A correctness criterion must be selected by which to measure the ....

.... of S[O i ] is correct only if the resulting state is S 0 (O i ) f(g(S[O i ] or S 0 (O i ) g(f(S[O i ] Conflict serializability must apply between concurrently executing transactions [2] Since methods can invoke other methods (possibly on other objects) a nested transaction system [7] is utilized 1 . Therefore, methods invoked on an object require executing a transaction. Should such a method invoke another method, the resulting execution is a sub transaction of the first. Two types of objects exist in our model. First, network based objects are always on the network so ....

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J.E.B. Moss. Nested Transactions -- An Approach to Reliable Distributed Computing. The MIT Press, 1985.

....of fine grained objects, and on increase in concurrency by running multiple objects. This solution is attractive, and may be suitable for core concepts of concurrent objects. The problem is that it would require the restructuring of systems, software, and programming techniques. Nested transactions[5] is another approach used to increase concurrency, in which the sending of multiple concurrent message (asynchronous sends) are emulated as subtransactions. This technique increases concurrency in the system, but the problem of blocking still remains. Response time does not improve for an object, ....

J. Eliot B. Moss. Nested Transaction: An approach to reliable distributed computing. MIT Press, 1985.

.... these problems we propose a top down oriented evaluation strategy similar to the wellknown SLD resolution of Prolog [MW88a] Our operational model features the immediate execution of operations in combination with backtracking, recovery by compensation [KLS98] and nested transactions [BBG89, Mos85, WS92] It is conceived w.r.t. the pomset based ULTRA instance, which has been presented in Section 3.4. During the evaluation of update queries within a top level transaction, requests for basic operations are immediately executed based on transaction processing techniques, rather than deferring ....

....is the integration of a sequential composition with the rule formalism. Essentially, the ideas of DLP are subsumed by the ULTRA approach and (Concurrent) Transaction Logic [BK94, BK96] Operations written in a DLP like update language can be performed as sequential or nested transactions [Mos85] Cronau [Cro90] has collected some methods for an adequate transaction processing. Chen defines an update calculus and a corresponding update algebra [Che95] The latter is an extension of the relational algebra and deals with deferred updates, concurrent sequential composition of these ....

J. E. B. Moss. Nested Transactions: An Approach to Reliable Distributed Computing. MIT Press, 1985.

....desirable to have more general control structures supporting reliable and distributed computing more effectively. Major concerns are more decomposable and finer grained control of concurrency and recovery. As a solution to these problems, the concept of nested transactions was proposed by Moss [Moss85] where single level transactions are enriched by an inner control structure. Such a mechanism allows for the dynamic decomposition of a transaction into a hierarchy of subtransactions thereby preserving all properties of a transaction as a unit and assuring atomicity and isolated execution for ....

....issues. Recovery problems are dealt with in [Moss87, Hrder87, Rothermel89] To facilitate our discussion, we introduce a model for nested transactions; it is designed so as to not prohibit parent child nor sibling parallelism. In Sec. 3, the basic concurrency control model invented by Moss [Moss85] is discussed. In some systems, it has been extended and refined by the concept of downward inheritance enabling transactions to pass on locks to their child transactions. In Sec. 4, we propose a number of generalizations and extensions for concurrency control in nested transactions. The concept ....

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Moss J.E.B.: Nested Transactions: An Approach to Reliable Distributed Computing. M.I.T. Press, Cambridge, 1985.

....are atomic are called atomic objects. Argus provides both conventional and atomic objects. Atomic objects use locks and a two phase commit protocol [Gray 79] to ensure object consistency. Argus provides a mechanism for constructing a hierarchy of actions called nested actions or subactions [Moss 81] Actions such as we have described thus far are called top level actions. All subactions have some action that 8 The Argus model of the distributed system state assumes that all objects have a stable representation on secondary storage and that any change to an object must by reflected in this ....

J. Eliot B. Moss. Nested Transactions: An Approach to Reliable Distributed Computing. PhD thesis, Massachusetts Institute of Technology, April 1981. Laboratory for Computer Science Tech. Report MIT/LCS/TR-260.

....Distributed atomic commit protocols are used to ensure the atomicity of a distributed transaction. Transactions can be nested, that is, a transaction can be started within another transaction. Top level transactions are those not enclosed within other transactions. Nested transactions [2] or subtransactions are useful for two reasons. First, they allow additional concurrency within a transaction (particularly in distributed systems) by running concurrently nested independent subtransactions. Second, the failure of a subtransaction does not force the parent transaction to fail, ....

J. E. B. Moss. Nested Transactions: An Approach to Reliable Distributed Computing. MIT Press, Cambridge, MA, 1985.

....specification S . 5.8 Nested transactions A nested transaction is a transaction that next to invoking read and write operations can invoke other transactions, called subtransactions. Of course, these subtransactions can in turn be nested transactions. Nested transactions were introduced by Moss [Mos85]. Van Rein [Rei97] argues that nested transactions are introduced by repeatedly refining an abstract action. A refinement of an abstract action introduces a transaction. When an action of that transaction is refined, another transaction is introduced and a nesting of transactions arises. A few ....

J.E.B. Moss. Nested Transactions: an approach to reliable distributed computing. MIT Press, 1985.

....to send consistency maintenance messages [23, 22, 6] and on the underlying networks themselves (e.g. Gigabit Ethernet, Myrinet [5] 2.2. LOTEC Sui and Graham [20] described a DSM based object programming system that uses a transactional execution model based on Moss closed nested transactions [16]. The consistency of their DSM is maintained using a modified form of Entry Consistency (EC) 4] Their consistency protocol, LOTEC, uses the synchronization operations defined by the nested object two phase locking (O2PL) concurrency protocol to drive its operation and the well defined semantics ....

....properties) Unlike conventional database transactions which are flat, the transactions in this system are nested. Each time a method invokes another method (normally on another object) a sub transaction is created. This transaction model is an extension of Moss closed nested transaction model [16] so the updates of sub transactions are invisible to other transactions until the sub transaction commits. Further, when a sub transaction commits, its updates become visible only to its parent transaction (and the parent s children) Only when all the sub transactions originating from an original ....

J. Moss. Nested Transactions: An Approach to Reliable Distributed Computing. MIT Press, 1985.

....To ensure simplicity of use, a transactional execution 1 Generally speakingitissafetoallowacopy of a shareddatum to be inconsistent when weknowitwill not be accessed. For example, because a lockrequiredtopermitaccess to thedata cannot be acquired. model based on Moss closed nested transactions [Mos85] is used. This ensures the correctness of concurrentexecutions based on the serializability of the transactions. The consistency of the DSM is then maintained usingamodified form of Bershad s Entry Consistency (EC) protocol [BZS93] Our new DSM consistency protocol, LOTEC, is both simple and ....

....data structuring in transaction processing systems, and as a required enabling technology for the integration of DSMand transactions on cluster based systems. 3 Nested Object Transactions and Nested Object 2PL We define nested object transactions as an extension of Moss nested transactions [Mos85] The use of nested object transactions directly supports the automation of consistency maintenance in our system. The start and end of methods define the boundaries of transactions and allowa compiler to insert synchronization operations (lockacquisition and release) automatically. Consistency ....

J.E.B. Moss. Nested Transactions -- An Approach to Reliable Distributed Computing. The MIT Press, 1985.

....sphere. Since transaction 2 has updated y, it is enclosed in both W x and W y spheres. In (3) the agt sphere of transaction 3 has been removed, but since the transaction aborted, its updates are not released to the system. 3.1. 2 Nested transaction systems In the nested transaction model [Mos85] transactions may contain sub transactions. Each sub transaction has a unique parent transaction and may commit or abort without forcing its parent to do so. When a sub transaction commits, it releases its updates only to its parent transaction, not to the entire system. A transaction may commit ....

J. Eliot Moss. Nested Transactions: An Approach to Reliable Distributed Computing. MIT Press, 1985.

....is straightforward to handle. Much of the TMF [Borr 81] implementation is within the operating system, although there is no support for nesting. Transactions which are composed of other transactions, or nested transactions, have been the subject of much current literature [Moss 81] Liskov 82] Reed 78] Svob 81] A transaction invoked from within a transaction, or subtransaction, appears atomic to its caller. That is, the operations it performs take place indivisibly with respect to both failures and concurrent computations, just as for traditional transactions. Thus a ....

....[Walker 83] To our knowledge, this is the first actual implementation of nested transactions on a distributed system. So far, others have produced only a preliminary, centralized implementation as part of the Argus language [Liskov 82] and a centralized simulation of a distributed implementation [Moss 81] Further, as discussed in the next section, LOCUS nested transactions provide additional functionality beyond that which is usually proposed. This paper summarizes the work reported in [Mueller 83] The implementation builds on simple nested transactions, reported in [Moore 82a] and [Moore ....

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Moss, J. Eliot B., "Nested Transactions: An Approach to Reliable Distributed Computing", Technical Report MIT/LCS/TR-260, Laboratory for Computer Science, M.I.T., 1981.

....of the implementation of rule processing on top of ObjectStore. Since event detection and rule processing need appropriate support from transaction management, we shortly discuss SAMOS transactions first. 2.4.2. 1 SAMOS Transactions SAMOS uses ObjectStore s model of closed nested transactions [54], which allows conditions and actions to be executed as subtransactions. Transaction management must be extended for three reasons: transaction events must be signalled, primitive event rule name : string cMode : couplingMode aMode : couplingMode priority : int time event method event ....

J.E.B. Moss. Nested Transactions: An Approach to Reliable Distributed Computing. MIT Press, 1985.

.... library provides undoability and persistence as orthogonal features, however they do not give a semantics for these features (while acknowledging that there is interaction between the features) The transaction model adopted in distributed programming languages is that of nested transactions [34, 37]. This is motivated by considerations of nested remote procedure calls in client server systems. For example, as depicted in Fig. 5, a request from Client A to Server B gives rise to further requests from Server B to Servers C and D. To make transactions scalable in a distributed environment where ....

J. E. B. Moss. Nested Transactions: An Approach to Reliable Distributed Computing. MIT Press, 1985.

....2 Concurrency Control in Nested Transactions 2.1 An Overview of Nested Transactions Nice Properties When executing more complex transactions, it turns out that single level transactions do not achieve optimal flexibility and performance. As a solution, the concept of NTs was popularized by Moss [13], where single level transactions are enriched by an inner control structure 3 . Such a mechanism allows for the dynamic decomposition of a transaction into a hierarchy of subtransactions thereby preserving all properties of a transaction as a unit and assuring atomicity and isolated execution ....

....of ancestors and descendants. The ancestor (descendant) relation is the reflexive transitive closure of the parent (child) relation. We use the term superior (inferior) for the nonreflexive version of the ancestor (descendant) The set of descendants of a transaction 2. The Moss CC method for NTs [13] allows only for upward inheritance of locks. 3. The ideas underlying the concept of NTs stem from Davies spheres of control [5, 6] 3 together with their parent child relationships is called the transaction s hierarchy. In the following, unless otherwise noted, we use the term transaction to ....

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Moss J.E.B.: Nested Transactions: An Approach to Reliable Distributed Computing. M.I.T. Press, 1985.

....Lightweight Transactions can commit a transaction in roughly five to ten microseconds, three orders of magnitude faster than a traditional implementation of standard transactions. These are by no means the only possible variants of the standard transaction model. For example, nested transactions [Moss85] allow a transaction to create sub transactions whose success or failure does not necessitate the success or failure of the enclosing transaction. VINO nests transactions when one extension invokes another. Sagas [Garcia Molina87] break a longrunning transactional process (saga) into a series of ....

....is minimal (a handful of instructions per log record) 6.3.2 Nested Transactions The purpose of the VINO transaction mechanism is to make it safe for a graft to call into the kernel. What if the kernel then causes another graft to be invoked When this happens, VINO creates a nested transaction [Moss85]. Unlike two unrelated transactions, a nested child transaction operates inside the context of its parent transaction. If a child transaction attempts to obtain a lock that is already held by its parent, the acquisition succeeds. In the case of two unrelated transactions, this is not the case: if ....

Moss, J. E. B., Nested Transactions: An Approach to Reliable Distributed Computing, MIT Press, Cambridge, MA (1985).

....the semantics of transactions across the multiple servers. Each server would have its own concept of a transaction and there would be no unifying concept of a global transaction. We do not see this as being difficult to add, indeed we could use nested, distributed, transactions as defined in [Mos85]. Figure 1 shows the architecture that we have implemented. A client server model requires communication between the client and the server. We have built what amounts to a special purpose Remote Procedure Call mechanism on top of the Berkeley socket mechanisms to handle this. We only support ....

J. Eliot B. Moss. Nested Transactions: An Approach to Reliable Distributed Computing. MIT Press Series in Information Systems. MIT Press, Cambridge, Mass., 1985.

....base de datos [12, 17] ninguno de ellos considera el modelo de transacciones anidadas como base para las aplicaciones de los usuarios. El modelo de transacci ones anidadas (TA) una transacci on compuesta de una jerarqu ia de subtransacciones, despu es de haber sido propuesto por Moss (ver [14]) ha sido objeto de vastos estudios. Se han desarrollado m ultiples sistemas que las soportan [15, 4] y algunos SMBD las proveen entre sus funcionalidades [1, 9] Sin embargo, pocos trabajos tratan el problema de verificaci on de restricciones en TA. Aunque parezca natural que para tales ....

....la verificaci on a un conjunto minimal de objetos, que es determinado en tiempo de ejecuci on y consiste unicamente de los objetos modificados por las transacciones que tocan la restricci on. 3 Transacciones anidadas y verificaci on de restricciones de integridad. Las transacciones anidadas [14] se ajustan a los sistemas de multi base de datos donde las transacciones largas pueden descomponerse en varias tareas l ogicamente independientes [19, 1, 4, 15] Una transacci on anidada (TA) es un arbol de transacciones de profundidad arbitraria donde los componentes son sub transacciones. La ....

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J. E. B. Moss. NestedTransactions: An Approach to Reliable Distributed Computing. MIT Press, Cambridge, MA, 1985.

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J. Moss. Nested Transactions: An Approach to Reliable Distributed Computing. Information Systems Series. The MIT Press, Cambridge, MA, 1985.

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J.E.B.Moss. Nested Transactions: An Approach to Reliable Distributed Computing. PhD thesis, MIT Press, Cambridge, MA, 1985.

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Moss, Eliot, [1985] Nested Transactions: An approach to reliable distributed computing, MIT Press, Cambridge.

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