Search results
Results From The WOW.Com Content Network
The Data Distribution Service (DDS) for real-time systems is an Object Management Group (OMG) machine-to-machine (sometimes called middleware or connectivity framework) standard that aims to enable dependable, high-performance, interoperable, real-time, scalable data exchanges using a publish–subscribe pattern.
Distributed Data Management Architecture (DDM) is IBM's open, published software architecture for creating, managing and accessing data on a remote computer. DDM was initially designed to support record-oriented files; it was extended to support hierarchical directories, stream-oriented files, queues, and system command processing; it was further extended to be the base of IBM's Distributed ...
Remote procedure call middleware enables a client to use services running on remote systems. The process can be synchronous or asynchronous. Object request broker With object request broker middleware, it is possible for applications to send objects and request services in an object-oriented system. SQL-oriented data access
Unlike parallel systems, in which the processors are tightly coupled and constitute a single database system, a distributed database system consists of loosely coupled sites that share no physical components. System administrators can distribute collections of data (e.g. in a database) across multiple physical locations.
In a centralized database system, the only available resource that needs to be shielded from the user is the data (that is, the storage system). In a distributed DBMS, a second resource needs to be managed in much the same manner: the network. Preferably, the user should be protected from the network operational details.
The Object Management Group's Data Distribution Service (DDS) provides message-oriented Publish/Subscribe (P/S) middleware standard that aims to enable scalable, real-time, dependable, high performance and interoperable data exchanges between publishers and subscribers. [7] The standard provides interfaces to C++, C++11, C, Ada, Java, and Ruby.
Every site in the system is assigned a vote V i. Let us assume that the total number of votes in the system is V and the abort and commit quorums are V a and V c, respectively. Then the following rules must be obeyed in the implementation of the commit protocol: V a + V c > V, where 0 < V c, V a V.
In practice most commercial database systems use strong strict two phase locking (SS2PL) for concurrency control, which ensures global serializability, if all the participating databases employ it. A common algorithm for ensuring correct completion of a distributed transaction is the two-phase commit (2PC).