barcode font vb.net Understanding transactions in Java

Generate Data Matrix in Java Understanding transactions

Understanding transactions
Create Data Matrix In Java
Using Barcode creator for Java Control to generate, create ECC200 image in Java applications.
www.OnBarcode.com
ECC200 Scanner In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
manager to start, commit, and roll back transactions. The transaction manager coordinates these requests among multiple resource managers, and each transaction phase may translate to numerous low-level resource commands issued by the resource managers. Next, we ll discuss how transactions are managed across multiple resources. In EJB, this is done with two-phase commits.
Making PDF417 In Java
Using Barcode generation for Java Control to generate, create PDF 417 image in Java applications.
www.OnBarcode.com
UPC - 13 Encoder In Java
Using Barcode printer for Java Control to generate, create GS1 - 13 image in Java applications.
www.OnBarcode.com
6.1.4 Two-phase commit
Create Matrix 2D Barcode In Java
Using Barcode creation for Java Control to generate, create Matrix Barcode image in Java applications.
www.OnBarcode.com
Encode USS Code 128 In Java
Using Barcode generation for Java Control to generate, create Code 128 image in Java applications.
www.OnBarcode.com
How transactions are managed in a distributed environment involving more than one resource is extremely interesting. The protocol commonly used to achieve this is called the two-phase commit. Imagine what would happen if no special precautions were taken while attempting to commit a transaction involving more than one database. Suppose that the first database commits successfully, but the second fails. It would be difficult to go back and undo the finalized changes to the first database. To avoid this problem, the two-phase commit protocol performs an additional preparatory step before the final commit. During this step, each resource manager involved is asked if the current transaction can be successfully committed. If any of the resource managers indicate that the transaction cannot be committed if attempted, the entire transaction is abandoned (rolled back). Otherwise, the transaction is allowed to proceed and all resource managers are asked to commit. As table 6.1 shows, only distributed transactions use the two-phase commit protocol. We have just reviewed how transactions work and what makes them reliable; now let s take a look at how EJB provides these services for the application developer.
Encode Code 128A In Java
Using Barcode encoder for Java Control to generate, create Code 128 Code Set A image in Java applications.
www.OnBarcode.com
Making Postnet In Java
Using Barcode creation for Java Control to generate, create USPS POSTal Numeric Encoding Technique Barcode image in Java applications.
www.OnBarcode.com
Table 6.1 A transaction may be either local or global. A local transaction involves one resource and a global transaction involves multiple resources. Property Number of resources Coordinator Commit protocol One Resource Manager Single-Phase Local Global Transaction Multiple Transaction manager Two-phase
Data Matrix Encoder In C#.NET
Using Barcode drawer for .NET Control to generate, create Data Matrix 2d barcode image in VS .NET applications.
www.OnBarcode.com
Drawing ECC200 In Visual Basic .NET
Using Barcode encoder for .NET Control to generate, create Data Matrix ECC200 image in Visual Studio .NET applications.
www.OnBarcode.com
Transactions and security
Making EAN 128 In Java
Using Barcode printer for Eclipse BIRT Control to generate, create UCC-128 image in Eclipse BIRT applications.
www.OnBarcode.com
Creating Matrix Barcode In Visual Basic .NET
Using Barcode encoder for .NET framework Control to generate, create 2D image in Visual Studio .NET applications.
www.OnBarcode.com
The XA protocol
Recognizing EAN13 In None
Using Barcode reader for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Print USS-128 In Objective-C
Using Barcode maker for iPad Control to generate, create UCC-128 image in iPad applications.
www.OnBarcode.com
To coordinate the two-phase commit across many different kinds of resources, the transaction manager and each of the resource managers must talk the same tongue, or use a common protocol. In the absence of such a protocol, imagine how sophisticated even a reasonably effective transaction manager would have to be. The transaction manager would have to be developed with the proprietary communication protocol of every supported resource. The most popular distributed transaction protocol used today is the XA protocol, which was developed by the X/Open group. Java EE uses this protocol for implementing distributed transaction services.
UCC - 12 Recognizer In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
Denso QR Bar Code Creation In Visual Basic .NET
Using Barcode generator for Visual Studio .NET Control to generate, create QR-Code image in .NET applications.
www.OnBarcode.com
6.1.5 Transaction management in EJB
Making European Article Number 13 In None
Using Barcode encoder for Software Control to generate, create EAN 13 image in Software applications.
www.OnBarcode.com
Painting Denso QR Bar Code In Java
Using Barcode generation for Eclipse BIRT Control to generate, create QR Code image in Eclipse BIRT applications.
www.OnBarcode.com
Transaction management support in EJB is provided through the Java Transaction API (JTA). JTA is a small, high-level API exposing functionality at the distributed transaction manager layer, typically provided by the application server. As a matter of fact, for the most part, as an EJB developer you will probably need to know about only one JTA interface: javax.transaction.UserTransaction. This is because the container takes care of most transaction management details behind the scenes. As an EJB developer, you simply tell the container where the transaction begins and ends (called transaction demarcation or establishing transaction boundaries) and whether to roll back or commit. There are two ways of using transactions in EJB. Both provide abstractions over JTA, one to a lesser and one to a greater degree. The first is to declaratively manage transactions through container-managed transaction (CMT); this can be done through annotations or the deployment descriptor. On the other hand, bean-managed transaction (BMT) requires you to explicitly manage transactions programmatically. It is important to note that in this version of EJB, only session beans and MDBs support BMT and CMT. The EJB 3 Java Persistence API is not directly dependent on either CMT or BMT but can transparently plug into any transactional environment while used inside a Java EE container. We ll cover this functionality when we discuss persistence in upcoming chapters. In this chapter, we ll explore CMT and BMT as they pertain to the two bean types we discussed in chapter 3 (session beans) and chapter 4 (MDBs).
Painting Code 3/9 In None
Using Barcode drawer for Online Control to generate, create Code 39 Extended image in Online applications.
www.OnBarcode.com
QR-Code Creator In C#.NET
Using Barcode creator for VS .NET Control to generate, create QR Code ISO/IEC18004 image in VS .NET applications.
www.OnBarcode.com
Copyright © OnBarcode.com . All rights reserved.