A distributed transaction operates within a distributed environment, typically involving multiple nodes across a network depending on the location of the data. A key aspect of distributed transactions is atomicity, which ensures that the transaction is completed in its entirety or not executed at all. It's essential to note that distributed transactions are not limited to

database In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and a ...

The Open Group The Open Group is a global consortium that seeks to "enable the achievement of business objectives" by developing " open, vendor-neutral technology standards and certifications." It has 900+ member organizations and provides a number of services ...

, a vendor consortium, proposed the X/Open Distributed Transaction Processing Model (X/Open XA), which became a de facto standard for the behavior of transaction model components. Databases are common transactional resources and, often, transactions span a couple of such databases. In this case, a distributed transaction can be seen as a

database transaction A database transaction symbolizes a unit of work, performed within a database management system (or similar system) against a database, that is treated in a coherent and reliable way independent of other transactions. A transaction generally rep ...

that must be synchronized (or provide

ACID An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...

properties) among multiple participating

s which are distributed among different physical locations. The isolation property (the I of ACID) poses a special challenge for multi database transactions, since the (global) serializability property could be violated, even if each database provides it (see also global serializability). In practice most commercial database systems use strong strict two-phase locking (SS2PL) for

concurrency control In information technology and computer science, especially in the fields of computer programming, operating systems, multiprocessors, and databases, concurrency control ensures that correct results for concurrent operations are generated, whil ...

, which ensures global serializability, if all the participating databases employ it. A common

algorithm In mathematics and computer science, an algorithm () is a finite sequence of Rigour#Mathematics, mathematically rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algo ...

for ensuring correct completion of a distributed transaction is the

two-phase commit Two-phase may refer to: * Two-phase electric power * Two-phase commit protocol * Two-phase flow * Two-phase locking * Binary phase, chemical compounds composed of two elements {{Disambig ...

(2PC). This algorithm is usually applied for updates able to commit in a short period of time, ranging from couple of milliseconds to couple of minutes. There are also long-lived distributed transactions, for example a transaction to book a trip, which consists of booking a flight, a rental car and a hotel. Since booking the flight might take up to a day to get a confirmation, two-phase commit is not applicable here, it will lock the resources for this long. In this case more sophisticated techniques that involve multiple undo levels are used. The way you can undo the hotel booking by calling a desk and cancelling the reservation, a system can be designed to undo certain operations (unless they are irreversibly finished). In practice, long-lived distributed transactions are implemented in systems based on

web services A web service (WS) is either: * a service offered by an electronic device to another electronic device, communicating with each other via the Internet, or * a server running on a computer device, listening for requests at a particular port over a n ...

. Usually these transactions utilize principles of compensating transactions, Optimism and Isolation Without Locking. The X/Open standard does not cover long-lived distributed transactions. Several technologies, including Jakarta Enterprise Beans and

Microsoft Transaction Server Microsoft Transaction Server (MTS) was software that provided services to Component Object Model (COM) software components, to make it easier to create large distributed applications. The major services provided by MTS were automated transaction ...

fully support distributed transaction standards.

Synchronization

event-driven architecture Event-driven architecture (EDA) is a software architecture paradigm concerning the production and detection of Event (computing), events. Event-driven architectures are Continuous design, evolutionary in nature and provide a high degree of fault to ...

s, distributed transactions can be synchronized through using

request–response In computer science, request–response or request–reply is one of the basic methods computers use to communicate with each other in a network, in which the first computer sends a ''request'' for some data and the second ''responds'' to the req ...

paradigm and it can be implemented in two ways: * Creating two separate queues: one for requests and the other for replies. The event producer must wait until it receives the response. * Creating one dedicated ephemeral queue for each request.

References

* * *

Synchronization

See also

References

Further reading