Managing Enterprise Java Beans Metadata

In this section:

When the server accesses a data source, it needs information on how to interpret the data stored there. For each data source the server will access, you create a synonym that describes the structure of the data source and the server mapping of the Enterprise Java Beans data types.


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Creating Synonyms

How to:

Reference:

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Synonyms define unique names (or aliases) for each Java Bean (EJB) table or view that is accessible from the server. Synonyms are useful because they hide the underlying data source's location and identity from client applications. They also provide support for extended metadata features of the server such as virtual fields and additional security mechanisms.

Using synonyms allows an object to be moved or renamed while allowing client applications to continue functioning without modification. The only modification required is a redefinition of the synonym on the server. The result of creating a synonym is a Master File and Access File, which represent the server's metadata.



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Procedure: How to Create a Synonym

To create a synonym, you must have previously configured the adapter. You can create a synonym from the Applications or Adapters pages of the Web Console.

  1. From the Web Console menu bar, click Applications.

    The Applications page opens.

  2. Click the New button and select Synonym from the drop-down menu.

    The Select adapter to configure or Select connection to create synonym pane opens.

  3. Click a connection for the configured adapter.

    The first of a series of synonym creation panes opens.

  4. Enter values for the parameters required by the adapter as described in the synonym creation parameters reference.
  5. After entering the parameter values, click Create Synonym.

    The Status pane indicates that the synonym was created successfully.

The synonym is created and added under the specified application directory.

Note:



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Reference: Synonym Creation Parameters for Enterprise Java Beans

The following list describes the parameters for which you will need to supply values, and related tasks you will need to complete in order to create a synonym for the adapter. These options may appear on multiple panes. To advance from pane to pane, click the buttons provided, ending with the Create Synonym button, which generates the synonym based on your entries.

Filter by Full or Partial JNDI Name

Select this check box to filter the collections for which you wish to create synonyms.

Application

Select an application directory. The default value is baseapp.

Prefix/Suffix

If you have tables with identical table names, assign a prefix or a suffix to distinguish them. For example, if you have identically named human resources and payroll tables, assign the prefix HR to distinguish the synonyms for the human resources tables. Note that the resulting synonym name cannot exceed 64 characters.

If all tables and views have unique names, leave the prefix and suffix fields blank.

Overwrite Existing Synonyms

To specify that this synonym should overwrite any earlier synonym with the same fully qualified name, select the Overwrite existing synonyms check box.

Note: The connected user must have operating system write privileges in order to recreate a synonym.

Select the EJBs

Select the EJBs for which you wish to create synonyms:

  • To select all EJBs in the list, select the check box to the left of the Default Synonym Name column heading.
  • To select specific EJBs, select the corresponding check boxes.
Default Synonym Name

This column displays the name that will be assigned to each synonym. To assign a different name, replace the displayed value.



Example: Creating a Synonym

CitiesEJB interfaces:

public interface CitiesEJBRemote extends javax.ejb.EJBObject { 
     public String getData() throws RemoteException;
     public int getIndex() throws RemoteException;
     public void setData(int num) throws RemoteException;
     public void setIndex(int ind) throws RemoteException; 
 }
public interface CitiesEJBHomeRemote extends javax.ejb.EJBHome { 
       public CitiesEJBRemote create()
         throws RemoteException,CreateException;
       public CitiesEJBRemote findByPrimaryKey(Integer primaryKey)
         throws FinderException, RemoteException; 
}

To create a synonym for the variable "Cities" from the Web Console or the Data Management Console:

  1. Optionally, filter the collection from which you wish to create synonyms and proceed to the second Create Synonym pane. If you leave this field blank, all EJBs will be displayed.
  2. Select CitiesEJB from the displayed list of EJBs, and click Create Synonym.

    The synonyms is created and added under the specified application directory (baseapp is the default).

    A status window displays the message: All Synonyms Created Successfully

  3. From the message window, click Applications on the menu bar.
  4. Open the baseapp application folder in the navigation pane and click the synonym CitiesEJB.
  5. Choose Edit as Text from the menu to view the generated Master File, then choose Edit Access File as Text to view the corresponding Access File.

Generated Master File cities.mas

FILENAME=CITIESG, SUFFIX=EJB     , $
$ ====================================================================
$ MFD generated for JNDI:CitiesEJB
$=====================================================================
  SEGMENT=PRIMARY_KEY, SEGTYPE=S0, $
$=====================================================================
$ constructors and parameters for PRIMARY_KEY:Integer
$=====================================================================
   GROUP=, ALIAS=K1, USAGE=A4, ACTUAL=A4, $
    FIELDNAME=K1F1, ALIAS=c0p0, USAGE=I11, ACTUAL=A4, $
  SEGMENT=OBJ01_CITIESEJBREMOTE, SEGTYPE=S0, PARENT=PRIMARY_KEY, $
$=====================================================================
$ OBJECT01, CitiesEJBRemote
$=====================================================================
    FIELDNAME=DATA, ALIAS=Data, USAGE=A256V, ACTUAL=A256V, MISSING=ON, $
    FIELDNAME=INDEX, ALIAS=Index, USAGE=I11, ACTUAL=A4, MISSING=ON, $

Generated Access File cities.acx

JNDINAME=CitiesEJB,
CONNECTION=MYCON,$
SEGNAME=PRIMARY_KEY,OBJECTNAME=Integer,$
SEGNAME=OBJ01_CitiesEJBRemote,OBJECTNAME=CitiesEJBRemote,$

The Master File root segment describes EJB Primary Keys. Each Primary Key is represented by a GROUP. Each KEY component is represented by an elementary FIELD in the GROUP. Only one active Primary Key is allowed in the request.

All other segments in the Master File describe the hierarchy of the OBJECTS that can be returned by EJB. Each GET Method of the OBJECT is represented by an elementary FIELD in the segment.



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Reference: Managing Synonyms

Once you have created a synonym, you can right-click the synonym name in the Adapter navigation pane of either the Web Console or the Data Management Console to access the following options.

Option

Description

Open

Opens the Master File for viewing and editing using a graphical interface. If an Access file is used it will be also available.

Edit as Text

Enables you to view and manually edit the Master File synonym.

Note: To update the synonym, it is strongly recommended that you use the graphical interface provided by the Open option, rather than manually editing the Master File.

Edit Access File as Text

Enables you to view and manually edit the Access File synonym.

Note: This option is available only when an Access File is created as part of the synonym.

Sample Data

Retrieves up to 20 rows from the associated data source.

Data Profiling

Data Profiling provides the data characteristics for synonym columns.

Alphanumeric columns provide the count of distinct values, total count, maximum, minimum, average length, and number of nulls.

Numeric columns provide the count of distinct values, total count, maximum, minimum, average value, and number of nulls.

Refresh Synonym (if applicable)

Regenerates the synonym. Use this option if the underlying object has been altered.

Data Management

Followed by these options, if applicable:

Recreate DBMS Table. Recreates the data source table. You are asked to confirm this selection before the table is regenerated. (Note that the table will be dropped and recreated. During the process, data may be lost.)

Delete All Data. Deletes all existing data. You are asked to confirm this selection before the data is deleted.

Insert Sample Data. Inserts specified number of sample records, populating all fields with counter values.

Reorganize. Recreates the data source table preserving original data.

Note: This option is not available in the Web Console.

Impact Analysis

Generates reports on procedures, synonyms, and columns that provide information on the flows/stored procedures available on a particular server, and the synonyms and columns they use. These reports enable you to evaluate changes before they are made by showing which components will be affected. See the Server Administration for UNIX, Windows, OpenVMS, IBM i, and z/OS manual for details about Impact Analysis reports.

Copy

Copies the synonym to the clipboard.

Delete

Deletes the synonym. You are asked to confirm this selection before the synonym is deleted.

Cut

Deletes the synonym and places it on the clipboard.

Properties

Displays the properties of the synonym, including physical location, last modified date, description, and privileges.



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Reference: Access File Keywords

Keyword

Description

JNDINAME

EJB JNDI name.

CONNECTION=connection_name

Indicates access to the specified Web Application Server.

Absence of CONNECTION=

Indicates access to the default Web Application Server.



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Data Type Support

The following chart provides information about the default mapping of Enterprise Java Beans data types to server data types:

 

EJB Data Type

Data Type

ACTUAL

USAGE

VOID

A1

A1

BYTE

A4

I4

SHORT

A4

I6

INT

A4

I11

LONG

A20

P20

FLOAT

A12

F12.2

DOUBLE

A20

D20.2

CHAR

A1

A1

STRING

A256V

A256V

BOOLEAN

A5

A5


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