Abstract: Transactional database replication techniques are disclosed that do not require altering of the database management system implementation. A replicator module includes a dynamic membership manager, which is configured to manage the persistent membership of a coordination group. The persistent membership can be, for example, a durable set of sites that can replicate changes amongst themselves. Changes from sites not in the persistent membership are discarded. The set of recovered members is a subset of the persistent membership. The persistent membership changes incrementally by either removing or adding members. Failed members may still be part of the persistent membership. The dynamic membership manager module manages the modification of the persistent membership, initialization of replicas, and propagation of membership information.

Abstract: Transactional database replication techniques are disclosed that do not require altering of the database management system implementation. A replicator module includes a dynamic membership manager, which is configured to manage the persistent membership of a coordination group. The persistent membership can be, for example, a durable set of sites that can replicate changes amongst themselves. Changes from sites not in the persistent membership are discarded. The set of recovered members is a subset of the persistent membership. The persistent membership changes incrementally by either removing or adding members. Failed members may still be part of the persistent membership. The dynamic membership manager module manages the modification of the persistent membership, initialization of replicas, and propagation of membership information.

Abstract: Transactional database replication techniques are disclosed that do not require altering of the database management system implementation. A replicator module includes a dynamic membership manager, which is configured to manage the persistent membership of a coordination group. The persistent membership can be, for example, a durable set of sites that can replicate changes amongst themselves. Changes from sites not in the persistent membership are discarded. The set of recovered members is a subset of the persistent membership. The persistent membership changes incrementally by either removing or adding members. Failed members may still be part of the persistent membership. The dynamic membership manager module manages the modification of the persistent membership, initialization of replicas, and propagation of membership information.

Abstract: Transactional database replication techniques are disclosed that do not require altering of the database management system implementation. A replicator module includes a dynamic membership manager, which is configured to manage the persistent membership of a coordination group. The persistent membership can be, for example, a durable set of sites that can replicate changes amongst themselves. Changes from sites not in the persistent membership are discarded. The set of recovered members is a subset of the persistent membership. The persistent membership changes incrementally by either removing or adding members. Failed members may still be part of the persistent membership. The dynamic membership manager module manages the modification of the persistent membership, initialization of replicas, and propagation of membership information.

Abstract: Transactional database replication techniques are disclosed. The techniques can be realized in many ways, such as in a replicator module that can be instantiated at each site in a distributed system. The techniques support a variety of data storage technologies such as traditional durable transactional databases as well as in-memory data storage systems, and a variety of data types such as relational, flat file, XML, and object-oriented data. Guaranteed levels of distributed transactional data consistency for both reads and writes are enabled for database applications. The techniques also support the ability of applications distributed across a network to perform updates concurrently, and the ability to replicate many standard database systems without needing to modify their intrinsic behavior or needing them to be aware of the replicator, and the ability to tolerate network and process failures without any change to the data consistency guarantees provided to the applications.

Abstract: Transactional database replication techniques are disclosed that do not require altering of the database management system implementation. A replicator module includes a dynamic membership manager, which is configured to manage the persistent membership of a coordination group. The persistent membership can be, for example, a durable set of sites that can replicate changes amongst themselves. Changes from sites not in the persistent membership are discarded. The set of recovered members is a subset of the persistent membership. The persistent membership changes incrementally by either removing or adding members. Failed members may still be part of the persistent membership. The dynamic membership manager module manages the modification of the persistent membership, initialization of replicas, and propagation of membership information.

Abstract: Transactional database replication techniques are disclosed that do not require altering of the database management system implementation. A replicator module includes a dynamic membership manager, which is configured to manage the persistent membership of a coordination group. The persistent membership can be, for example, a durable set of sites that can replicate changes amongst themselves. Changes from sites not in the persistent membership are discarded. The set of recovered members is a subset of the persistent membership. The persistent membership changes incrementally by either removing or adding members. Failed members may still be part of the persistent membership. The dynamic membership manager module manages the modification of the persistent membership, initialization of replicas, and propagation of membership information.

Abstract: Distributed transaction and lock management techniques are disclosed that manage and regulate access to distributed data. A lock manager module is provided for regulating access to resources by applications in a system having a number of nodes each communicatively coupled to a network. The module can be configured to be fault tolerant. In one embodiment, the module uses a totally ordered transport that imposes total ordering protocols on messaging between nodes. The module can exploit the multicast ability of the network (e.g., Ethernet or other network features that enable multicast). The module includes a queue for each resource, the queue identifying the node that owns distributed lock for that resource. Each queue can be replicated across the nodes in a distributed configuration.

Abstract: Distributed transaction and lock management techniques are disclosed that manage and regulate access to distributed data. A lock manager module is provided for regulating access to resources by applications in a system having a number of nodes each communicatively coupled to a network. The module can be configured to be fault tolerant. In one embodiment, the module uses a totally ordered transport that imposes total ordering protocols on messaging between nodes. The module can exploit the multicast ability of the network (e.g., Ethernet or other network features that enable multicast). The module includes a queue for each resource, the queue identifying the node that owns distributed lock for that resource. Each queue can be replicated across the nodes in a distributed configuration.

Abstract: Transactional database replication techniques are disclosed that do not require altering of the database management system implementation. A replicator module includes a dynamic membership manager, which is configured to manage the persistent membership of a coordination group. The persistent membership can be, for example, a durable set of sites that can replicate changes amongst themselves. Changes from sites not in the persistent membership are discarded. The set of recovered members is a subset of the persistent membership. The persistent membership changes incrementally by either removing or adding members. Failed members may still be part of the persistent membership. The dynamic membership manager module manages the modification of the persistent membership, initialization of replicas, and propagation of membership information.

Abstract: A two-stroke internal combustion engine 7 is provided. The engine 7 has a first piston 12 with a head 16 and a second piston 28 with a head 30 which faces the first piston 12. First and second pistons 12, 28 have valved exhaust lines 20 intersecting with the piston heads 16, 30. A sleeve 32 encircles the first piston 12. The sleeve 32 has a closed end 36 forming a first intake space 40. A second sleeve 44 encircles the second piston 28 and has a closed end 50 forming a second intake space 54. Check valves 56 are provided for allowing flow of air into the intake spaces 40, 54. A cylinder 60 is slidably mounted on the pistons 12, 28 for reciprocal movement thereon. The cylinder 60 is H-shaped having an internal pressure boundary 64 forming separate combustion chambers 70, 72 with the pistons 12, 28. The cylinder 60 has ends 76, 86 sealed with the pistons 12, 28 and the sleeves 32, 44 forming a variable volume induction/compression area in the intake spaces 40, 54.