Method extension assembly settings

Method extensions are IBM extensions to the standard J2EE deployment descriptors for EJBs Version 1.x-compliant beans. Method extension settings define transaction isolation levels for methods and control the delegation of a principal's credentials.

 

Method type

Specifies the type of the enterprise bean method.

Data type String
Range Valid values are Home , Remote , and Unspecified .

 

Name

Specifies the name of an enterprise bean method, or the asterisk character (*). The asterisk is used to denote all methods of an enterprise bean's remote and home interfaces.

 

Parameters

Contains a list of fully qualified Java type names of the method parameters. Used to identify a single method among multiple methods with an overloaded method name.

 

Isolation level attributes

The transaction isolation level determines how isolated one transaction is from another. This can be set for individual methods in an enterprise bean or for all methods in the enterprise bean. An asterisk is used to indicate all methods in the bean. This setting is not applicable for EJB 2.x-compliant beans.

Within a transactional context, the isolation level associated with the first method call becomes the required isolation level for all methods called within that transaction. If a method is called with a different isolation level from that of the first method, the java.rmi.RemoteException exception is thrown.

 

Isolation level

Specifies the level of transactional isolation.

The container uses the transaction isolation level attribute as follows:

Data type String
Range Valid values are Serializable , Repeatable read , Read committed , and Read uncommitted

 

Serializable

This level prohibits the following types of reads:

  • Dirty reads, in which a transaction reads a database row containing uncommitted changes from a second transaction.

  • Nonrepeatable reads, in which one transaction reads a row, a second transaction changes the same row, and the first transaction rereads the row and gets a different value.

  • Phantom reads, in which one transaction reads all rows that satisfy an SQL WHERE condition, a second transaction inserts a row that also satisfies the WHERE condition, and the first transaction applies the same WHERE condition and gets the row inserted by the second transaction.

 

Repeatable read

This level prohibits dirty reads and nonrepeatable reads, but it allows phantom reads.

 

Read committed

This level prohibits dirty reads but allows nonrepeatable reads and phantom reads.

 

Read uncommitted

This level allows dirty reads, nonrepeatable reads, and phantom reads.

 

Access intent - Intent type

Specifies whether to load the enterprise bean as read-only or for update. This setting is applicable only for EJB 1.x-compliant beans.

This setting is applicable for the following types of beans:

  • EJB 1.x-compliant entity beans

  • Enterprise beans with CMP version 1.x that are packaged in EJB 2.x-compliant modules

To specify the access intent for EJB 2.x-compliant beans, select an access intent policy.

Data type String
Range Valid values are Read or Update

 

Finder descriptor - User

Specifies that the user has provided a finder helper class in the entity bean's home interface. The class contains specialized finder methods. This setting is applicable only for EJB 1.x-compliant entity beans.

 

Finder descriptor - EJB QL

Describes the semantics of a finder method that uses EJB QL (Enterprise JavaBeans query language). This setting is applicable only for EJB 1.x-compliant entity beans.

EJB QL is a declarative, SQL-like language that is intended to be compiled to the target language of the persistent datastore used by a persistence manager. The language is independent of the bean's mapping to a relational datastore and is therefore portable. The EJB query specifies a search based on the persistent attributes and relationships of the bean. An EJB query can contain the following clauses:

  • SELECT (optional), which specifies the EJB objects to return

  • FROM (required), which specifies the collections of objects to which the query is to be applied

  • WHERE (optional), which contains search predicates over the collections

  • ORDER BY (optional), which specifies the ordering of the resulting collection

 

Finder descriptor - Full SELECT

Describes the semantics of a finder method that uses an SQL SELECT clause. For information on restrictions, see the documentation for the Deployment Tool for EJBs.

 

Finder descriptor - WHERE clause

Describes the semantics of a finder method that uses an SQL WHERE clause. This clause restricts the results that are returned by the query. For information on restrictions, see the documentation for the Deployment Tool for EJBs.

 

Security identity

Specifies whether a principal's credential settings are to be handled as indicated in the Run-As mode setting. If this is enabled, the Run-As mode setting can be edited.

 

Description

Contains further information about the security instructions.

 

Run-As mode

Specifies the credential information to be used by the security service to determine the permissions that a principal has on various resources.

At appropriate points, the security service determines whether the principal is authorized to use a particular resource based on the principal's permissions. If the method call is authorized, the security service acts on the principal's credential settings according to the Run-As mode setting of the enterprise bean.

Data type Enumerated integer
Range Valid values are Use identity of caller , Use identity of EJB server , and Use identity assigned to specified role

Additional information about valid values for this setting follows:

 

Use identity of caller

The security service makes no changes to the principal's credential settings.

 

Use identity of EJB server

The security service alters the principal's credential settings to match the credential settings associated with the EJB server.

 

Use identity assigned to specified role

A principal that has been assigned to the specified security role is used for the execution of the bean's methods. This association is part of the application binding in which the role is associated with a user ID and password of a user who is granted that role.

 

Role name

Specifies the name of a security role. If Run-As mode is set to Use identity assigned to specified role , a principal that has been granted this role is used.

 

Description

Contains further information about the security role.

Assembling EJB modules
Access intent assembly settings
Application assembly performance checklist
Tuning parameter index

 

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