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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.
How to: Reference: |
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.
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.
The Applications page opens.
The Select adapter to configure or Select connection to create synonym pane opens.
The first of a series of synonym creation panes opens.
The Status pane indicates that the synonym was created successfully.
The synonym is created and added under the specified application directory.
Note:
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.
Select this check box to filter the collections for which you wish to create synonyms.
Select an application directory. The default value is baseapp.
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.
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 for which you wish to create synonyms:
This column displays the name that will be assigned to each synonym. To assign a different name, replace the displayed value.
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:
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
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.
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. |
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 |
iWay Software |