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Topic: Distributed transactions

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	Distributed Transactions
		XA resources--These are used by a transaction manager in coordinating the transaction branches of a distributed transaction.
		It associates and disassociates distributed transactions with the transaction branch operating in the XA connection instance that produced this XA resource instance.
		, disassociating the transaction branch from its distributed transaction.
	www.stanford.edu /dept/itss/docs/oracle/9i/java.920/a96654/xadistra.htm (3504 words)

	Distributed Transactions Concepts
		A session tree is a hierarchical model of the transaction that describes the relationships among the nodes that are involved.
		Consequently, distributed transaction processing is more complicated, because Oracle must coordinate the committing or rolling back of the changes in a transaction as a self-contained unit.
		The distributed transaction commits with the highest global SCN among all the databases involved.
	download-west.oracle.com /docs/cd/A87860_01/doc/server.817/a76960/ds_txns.htm (4769 words)

	Avoiding Distributed Transactions
		It queries the transaction journal and finds a number of transactions which were committed to it.
		These transactions may be old, so the transaction journal needs to be persistent up to some checkpoint in the past.
		I tend to associate a transaction log with the middle-tier, which is conveniently at the 'center of things' anyway.
	c2.com /cgi/wiki?AvoidingDistributedTransactions (842 words)

	Chapter 21 Distributed Transactions
		The transaction is managed from the node at which it is submitted, the "home node".
		When the transaction is ready to commit, the home node is responsible for ensuring that commitment is atomic over all the objects involved.
		On restart, the recovery procedures must ascertain the transactions for which commitment was in progress when the crash occurred and the decision reached, if any.
	www.cl.cam.ac.uk /Teaching/2000/ConcSys/csig2/59.html (1021 words)

	Managing Distributed Transactions (Site not responding. Last check: 2007-09-18)
		Figure 32-1, illustrates a failure during the commit of a distributed transaction.
		Determining the Global Transaction ID The global transaction ID is the common transaction ID that is the same on every node for a distributed transaction.
		The SCNs in a distributed transaction are synchronized at the end of each remote SQL statement and at the start and end of each transaction.
	www.cs.umb.edu /cs634/ora9idocs/server.920/a96521/ds_txnman.htm (4532 words)

	Distributed Transaction Processing (Site not responding. Last check: 2007-09-18)
		Distributed transaction processing has become a very important part of distributed computing.
		Such issues were the need for reconciling chained and unchained transactions, context management, multiprotocol and transaction-model independent transaction managers and the manipulation of transactional objects.
		Distributed transactions require transaction processing support either from their communications protocols or from protocols at some higher layer.
	www.cs.ucy.ac.cy /~cssamara/samaras/distr_transaction.htm (1027 words)

	DBAsupport.com : Oracle 9i Central : Autonomous and Distributed Transactions in Oracle 8i/9i
		Unlike the non-distributed transactions that involve SQL statements against a single node of a database (the local node where the user is logged in), the Distributed transaction involves all DML (Data Manipulation Language) operations on two or more nodes of a distributed database.
		As the autonomous transaction is an independent transaction, you cannot rollback to a savepoint defined in the main transaction.
		Consider a scenario where you have a distributed transaction in which you require to commit or rollback a change in a remote table followed by an insert/update/query on your local database, or vice versa.
	www.dbasupport.com /oracle/ora9i/autonomoustrans.shtml (1242 words)

	JDBC: Distributed Transactions (Site not responding. Last check: 2007-09-18)
		Although beans with container-managed transactions require less coding, they have one limitation: When a method is executing, it can be associated with either a single transaction or no transaction at all.
		This article describes the principles of transaction management in an EJB from the perspective of a Java developer; that is, it explains what the developer has to do to take advantage of the transaction management facilities offered by the EJB1.1 specification.
		When a transaction is rolled back all changes are lost and the database reverts back to the state of the last successfully committed transaction.
	www.javaolympus.com /J2SE/Database/JDBC/JDBCDistributedTransactions.jsp (1041 words)

	Distributed Transactions Overview
		Implementing robust applications in a distributed environment is difficult because these applications are subject to many types of failures, including failures of the client, the servers, and the network.
		The transaction manager reads its log file to determine the outcomes of transactions for which it was the commit coordinator.
		For outgoing transactions, the transaction manager contacts each subordinate transaction manager to which it sent the transaction and informs them of the transaction outcome.
	www.microsoft.com /windows2000/en/advanced/help/addtccpt_88fr.htm (680 words)

	Managing Distributed Transactions (Site not responding. Last check: 2007-09-18)
		Because the commit point site stores information about the status of the transaction, the commit point site should not be a node that is frequently unreliable or unavailable in case other nodes need information about the transaction's status.
		Determining the Global Transaction ID The global transaction ID is the common transaction ID that is the same on every node for a distributed transaction.
		The SCNs in a distributed transaction are synchronized at the end of each remote SQL statement and at the start and end of each transaction.
	saturn.uab.es /server.920/a96521/ds_txnman.htm (4532 words)

	Distributed Transactions Are Evil
		The problem is that by distributing a transaction, you create a very tight dependency between two independent physical devices.
		The advantage of using a distributed transactions is that they are a workable solution to a concrete problem.
		Distributed transactions have the commonly used meaning of distributed database transaction, and they are not evil.
	c2.com /cgi/wiki?DistributedTransactionsAreEvil (3983 words)

	32 Distributed Transactions Concepts
		As the statements in a distributed transaction are issued, the database defines a session tree of all nodes participating in the transaction.
		Consequently, distributed transaction processing is more complicated, because the database must coordinate the committing or rolling back of the changes in a transaction as a self-contained unit.
		The first phase in committing a distributed transaction is the prepare phase.
	www.stanford.edu /dept/itss/docs/oracle/10g/server.101/b10739/ds_txns.htm (4482 words)

	Distributed Transactions
		The transactions that constitute a distributed transaction might be in the same database, but more typically are in different databases and often in different locations.
		In the JDBC 2.0 extension API, distributed transaction functionality is built on top of connection pooling functionality, described under "Connection Pooling".
		XA resources--These are used by a transaction manager in coordinating the transaction branches of a distributed transaction.
	www.boku.ac.at /oradoc/ias/1.0.2/buslog.102/a83724/xadistr1.htm (1009 words)

	Using WebLogic jDriver for Oracle/XA in Distributed Transactions
		The reason for the last two differences is because when the WebLogic jDriver for Oracle/XA participates in a distributed transaction, it is the external Transaction Manager that is demarcating and coordinating the distributed transaction.
		Transactions use the transaction isolation level set on the connection or the default transaction isolation level for the database.
		Listing 4-3 shows a distributed transaction involving two database connections and implemented as a business method within a session bean.
	e-docs.bea.com /wls/docs81/oracle/trxjdbcx.html (1334 words)

	Distributed Transactions (.NET Framework Developer's Guide)
		Distributed transaction processing (TP) systems are designed to facilitate transactions that span heterogeneous, transaction-aware resources in a distributed environment.
		Supported by a distributed TP system, your application can combine into a transactional unit such diverse activities as retrieving a message from a Message Queuing queue, storing the message in a Microsoft SQL Server database, and removing all existing references to the message from an Oracle Server database.
		Because they span multiple data resources, it is important that distributed transactions enforce the ACID properties to maintain data consistency across all resources.
	msdn.microsoft.com /library/en-us/cpguide/html/cpcondistributedtransactions.asp (380 words)

	ONJava.com -- Using Global/Distributed Transactions in Java/JDBC with Oracle Real Application Clusters
		A global transaction is a mechanism that allows a set of programming tasks, potentially using more than one resource manager and potentially executing on multiple servers, to be treated as one logical unit.
		Once a process is in transaction mode, any service requests made to servers may be processed on behalf of the current transaction.
		Problems occur when connections participating in a distributed transaction are routed to different instances of an RAC cluster.
	www.onjava.com /pub/a/onjava/2005/12/21/global-distributed-transactions-with-oracle-rac.html (736 words)

	Distributed Transactions (Stefan Tilkov's Random Stuff)
		I have been involved in quite a few projects where some technology or other was being evaluated, and distributed transactions (2PC style) always were deemed to be a critical component.
		Although distributed transactions are deemed the holy grail of enterprise computing by some, I think they are used rarely, and if they are used, it’s absolutely never in a scenario where the resource managers being coordinated are not very tightly related.
		In fact, I believe that in any loosely-coupled system, transactions can’t be pushed into the supporting framework or infrastructure at all — you need to implement the logic for handling failed commits with at least the same effort as your success cases.
	www.innoq.com /blog/st/2004/05/distributed_transactions.html (258 words)

	Distributed Transactions (Site not responding. Last check: 2007-09-18)
		It associates and disassociates distributed transactions with the transaction branch operating in the XA connection instance that produced this XA resource instance.
		, disassociating the transaction branch from its distributed transaction.
		The transaction manager calls this method during recovery to obtain the list of transaction branches that are currently in prepared or heuristically completed states.
	www.di.unipi.it /~ghelli/bdl/A97329_03/web.902/a90211/xadistra.htm (3320 words)

	Mobile and Pervasive Computing Research at the University of Florida (Site not responding. Last check: 2007-09-18)
		They are long live transactions whose logic is coupled to several mobility parameters such as location, direction of movement and speed.
		Classical atomicity, concurrency and recovery solutions orginially designed for distributed transactions must be revisited to accommodate the new nature and requirements for mobile transactions.
		We are currently working on several transaction models with recent focus on the disconnected (also known in the literature as two-tier) transaction case.
	www.harris.cise.ufl.edu /projects/mobile-transactions.htm (297 words)

	ZeroC Forums - How to handle distributed transactions
		It can however not commit the database transaction as within that same transaction other database operations are executed via other interfaces to create other objects which may be associated with the file.
		As for your question about distributed transactions, this is one of the most complicated topics, regardless of what middleware you use.
		Distributed transactions are only really needed if you actually have physically seperate objects cooperating on multiple operations that should together have one atomic result.
	www.zeroc.com /vbulletin/showthread.php?t=917 (781 words)

	Electronic Commerce Fuels Need for Distributed Transactions
		That is not the case with a two-phase commit, because both transactions are committed as one unit - either both updates are committed or both get rolled back as a unit.
		Also, a two-phase commit transaction's actions are taken as a group and do not violate any of the integrity constraints associated with a system.
		Companies now have to perform transaction processing across the Internet; so there is currently a need to be more open with the operational data that, in the past, has been managed on the large back-end repositories.
	www.dmreview.com /article_sub.cfm?articleId=1499 (1869 words)

	INF: Resolving Deadlocks With Distributed Transactions
		In distributed transactions, deadlocks can occur and application developers planning to implement distributed transactions with SQL Server 6.5 need to understand their options.
		If the application has tight control over what distributed transactions are being performed, it can serialize access to common resources such that any deadlocks that might occur would be contained within a single SQL Server where they could be detected and dealt with as normal deadlocks are handled.
		For instance, if the intention is to maintain transactional integrity between three tables on three different SQL Servers (T1 on SERVER1, T2 on SERVER2, and T3 on SERVER3), you should always issue the table modification queries in the same table order for any distributed transaction that affects these tables.
	support.microsoft.com /kb/149935 (469 words)

	Transactions in Distributed Environments
		Transactions are important to create atomicity for a set of otherwise distinct actions.
		On the other hand, message queuing is usually not an appropriate IPC mechanism for transactions, as there may be no reply, or the timeliness of a reply might not be guaranteed.
		Transaction support is also being defined for DCOM and CORBA, which will give these technologies a huge advantage over vanilla RPCs and direct socket I/O. Whether the transaction technology built into these mechanisms is XA compliant remains to be seen.
	mywebpages.comcast.net /scottnichol/disttran.htm (715 words)

	33 Managing Distributed Transactions
		A pending transaction can be forced to commit at the discretion of a database administrator.
		The automatic recovery features of the database transparently complete any in-doubt transaction so that the same outcome occurs on all nodes of a session tree (that is, all commit or all roll back) after the network or system failure is resolved.
		Figure 33-1, illustrates a failure during the commit of a distributed transaction.
	www.stanford.edu /dept/itss/docs/oracle/10g/server.101/b10739/ds_txnman.htm (4682 words)

	Distributed Commerce Transactions with Timing Deadlines and Direct Trust - Ketchpel, Garcia-Molina (ResearchIndex) (Site not responding. Last check: 2007-09-18)
		Abstract: In a multi-party transaction such as fulfilling an information request from multiple sources (also called a distributed commerce transaction), agents face risks from dealing with untrusted agents.
		These risks are compounded in the face of deadlines, e.g., an agent may fail to deliver purchased goods by the time the goods are needed.
		We present a distributed algorithm that mitigates these risks, showing that it is sound (produces only safe multi-agent action sequences) and complete (finds a safe...
	citeseer.ist.psu.edu /ketchpel97distributed.html (261 words)

	Special Edition Using Microsoft® Visual Studio for Enterprise Development -- Ch 24 -- Deploying Distributed ...
		Before the transfer, each account is internally consistent (all transactions sum to the current balance), and all accounts are collectively consistent (account balances for a depositor sum to his total balance with the bank).
		Because the intermediate states of a transaction aren't visible outside the transaction and because each transaction is "all or nothing," transactions appear to execute separately and sequentially.
		Transaction Server provides all the needed additional capabilities to make the application multiuser and leverages DTC to provide distributed transaction processing.
	cma.zdnet.com /book/visualstudio/ch24/ch24.htm (7232 words)

	Distributed Transactions with Indigo and WS-AT
		In my opinion, if you need to flow a transaction between two services then your services aren't really services in that their autonomy is compromised.
		As all we know, from a SOA perspective, services should be autonomous and if you coordinate them within a distributed transaction, they are not so autonomous.
		Last but not least: Indigo supports distributed transactions greatly, in a way that is compliant with a common specification (made by Microsoft, IBM and BEA).
	weblogs.asp.net /paolopia/archive/2005/06/23/414412.aspx (812 words)

	Managing Transactions in a Distributed Environment
		In the world of distributed objects, a transaction is a unit of work composed of a set of operations on objects.
		The ITS Transaction Service includes logging and recovery, and provides the recovery information necessary to ensure that a transaction can always be restored to its rightful state-ensuring consistency between resources, even in the event of system failure.
		Since ITS works in distributed environments, the number of physical servers to implement the application may be 1, 2, 3 or more—depending on customer requirements such as transaction volume or system availability.
	community.borland.com /article/0,1410,26388,00.html (5019 words)

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