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6.6.5.0.1: Assembly properties for entity beans

6.6.5.0.1: Assembly properties for entity beans

EJB name (Required, String)
Specifies a logical name for the enterprise bean. This name must be unique within the EJB module. There is no relationship between this name and the JNDI name.

Display name
Specifies a short name that is intended to be displayed by GUIs.

Description
Contains text describing the entity bean.

Home Interface (Required, String)
Specifies the full name of the enterprise bean's home interface class--for example, com.ibm.ejs.doc.account.AccountHome.

Remote Interface (Required, String)
Specifies the full name of the enterprise bean's remote interface class--for example, com.ibm.ejs.doc.account.Account.

EJB class (Required, String)
Specifies the full name of the enterprise bean class--for example, com.ibm.ejs.doc.account.AccountBean.

Persistency
Specifies whether an entity bean manages its own persistent storage or whether storage is managed by the container. The valid values are Bean-managed and Container-managed.

Primary key field
Specifies the name of a simple primary key. Simple primary keys map to a single field in the entity bean class and are made up of primitive Java data types (such as integer or long). If exactly one CMP field is the primary key, it can be specified here.

Primary key class (Required, String)
Specifies the full name of the bean's primary key class--for example, com.ibm.ejs.doc.account.AccountKey. Composite primary keys map to multiple fields in the entity bean class (or to data structures built from the primitive Java data types), and must be encapsulated in a primary key class. More complicated enterprise beans are likely to have composite primary keys, with multiple instance variables representing the primary key. A subset of the container-managed fields is used to define the primary key class associated with each instance of an enterprise bean.

Reentrant
Specifies whether the entity bean is reentrant or not. If an enterprise bean is reentrant, it can invoke methods on itself or call another bean that invokes a method on the calling bean. Only entity beans can be reentrant. If an entity bean is not reentrant and a bean instance is executing a client request in a transaction context and another client using the same transaction context makes a request on the same bean instance, the EJB container throws the java.rmi.RemoteException exception to the second client. If a bean is reentrant, the container cannot distinguish this type of illegal loopback call from a legal concurrent call and the bean must be coded to detect illegal loopback calls.

Small icon
Specifies a JPEG or GIF file containing a small image (16x16 pixels). The image is used as an icon to represent the entity bean in a GUI.

Large icon
Specifies a JPEG or GIF file containing a large image (32x32 pixels). The image is used as an icon to represent the entity bean in a GUI.

Inheritance root
Specifies whether or not the enterprise bean is at the root of an inheritance hierarchy.

Bean Cache -- Activate at
Specifies the point at which an enterprise bean is activated and placed in the cache. Removal from the cache and passivation is also governed by this setting. Valid values are Once and Transaction. Once indicates that the bean is activated when it is first accessed in the server process, and passivated (and removed from the cache) at the discretion of the container--for example, when the cache becomes full. Transaction indicates that the bean is activated at the start of a transaction and passivated (and removed from the cache) at the end of the transaction. The default value is Transaction.

Bean Cache -- Load at
Specifies when the bean loads its state from the database. The value of this property implies whether the container has exclusive or shared access to the database. Valid values are Activation and Transaction. Activation indicates that the bean is loaded when it is activated (Once or Transaction) and implies that the container has exclusive access to the database. Transaction indicates that the bean is loaded at the start of a transaction and implies that the container has shared access to the database. The default is Transaction.

The settings of the Activate at and Load at properties govern which commit options are used. The commit options are described in detail in the Enterprise JavaBeans specification, version 1.1.

  • For Commit Option A (implies exclusive DB access), use Activate at = Once and Load at = Activation. This option reduces database I/O (avoids calls to the ejbLoad function) but serializes all transactions accessing the bean instance. Option A can increase memory usage by maintaining more objects in the cache, but could provide better response time if bean instances are not generally accessed concurrently by multiple transactions.

  • For Commit Option B (implies shared DB access), use Activate at = Once, Load at = Transaction. Option B can increase memory usage by maintaining more objects in the cache. However, because each transaction creates its own copy of an object, there can be multiple copies of an instance in memory at any given time (one per transaction), requiring that the database be accessed at each transaction. If an enterprise bean contains a significant number of calls to the ejbActivate function, using Option B can be beneficial because the required object is already in the cache. Otherwise, this option does not provide significant benefit over Option A.

  • For Commit Option C (implies shared DB access), use Activate at = Transaction and Load at = Transaction. This option can reduce memory usage by maintaining fewer objects in the cache, however, there can be multiple copies of an instance in memory at any given time (one per transaction). This option can reduce transaction contention for enterprise bean instances that are accessed concurrently but not updated.

Locale location
Specifies the language used when the enterprise bean retrieves and displays message catalogs: the local language of the client that invoked the bean method or the local language of the server where the bean is running. Valid values are server and caller.

Local Transactions -- Boundary
Specifies when a local transaction begins. The default behavior is that the local transaction begins when the method begins and ends when the method ends.

Local Transactions -- Unresolved action
Specifies the action the container must take if resources are uncommitted by an application in a local transaction. A local transaction context is created when a method executes in what the EJB specification refers to as an unspecified transaction context. Valid values are Rollback and Commit. The default is Rollback.

Local Relationship Roles - Name
Information is not available.

Local Relationship Roles - Source EJB Name
Information is not available.

Local Relationship Roles - is Forward
Information is not available.

Local Relationship Roles - is Navigable
Information is not available.

JNDI name
Specifies the JNDI name of the bean's home interface. This is the name under which the enterprise bean's home interface is registered and therefore is the name that must be specified when an EJB client does a lookup of the home interface.

Data Source - JNDI name
Specifies the JNDI name for the bean's data source.

Default Authorization - User ID
Specifies the default user ID for connecting to a data source.

Default Authorization - Password
Specifies the default password for connecting to a data source.
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