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• distributed anywhere on the network and are accessible to any CORBA-compliant client. Up to three levels of security and RSA encryption ensure the privacy of all data passed between the client and the server.

• Manageability: New components stand alone and easily are added to the repository, which makes them available to the Object Factory immediately (without having to restart the server).
• Reusability: You can build new applications entirely from existing components. Also, because the AIS Web Development Suite is based on standard IDL, you can write client applications in any language that supports interface definition language (IDL) mapping, including C/C++ and SmallTalk.
• Maintainability: Components developed with the AIS Web Development Suite are not tightly bound with the server or each other. Repository management allows individual components to be temporarily disabled while modifications are applied, without affecting other components. The Client Configuration Manager provides the capability to automatically update client configurations.
• Flexibility: Numerous deployment options enable you to distribute and redistribute ORB components across the network. The independent Locator service and Repository Replication service simplify the process of reorganizing distributed services.
• Extensibility: The component-based architecture of the server enables developers to integrate custom Object Factories, authentication services, and external interfaces.

Tools

The AIS Web Development Suite provides a number of tools and utilities, including the Database Application Support and Object Interface Generator, Server Configuration Manager, Repository and Replication Manager, Security Manager, and Client Configuration Manager.

The Database Application Support and Object Interface Generator greatly simplifies the development process of online transaction processing (OLTP) and online analytical processing (OLAP) applications by producing IDL, object implementations, and client interfaces that encapsulate communication between implementations and data sources; it also supports interaction between client objects and the ORB. You can use this feature to generate application support for Oracle databases as well.

To understand the power of the AIS Web Development Suite, take a look at the famous scott/tiger Oracle schema. The suite supports full OLTP application interface over the Web or an intranet by generating four files that are the key links between your RDBMS applications and your new Web-based objects.

The following four files would be created if you used this tool with the scott/tiger database:

deptpack.sql: A script to create a view, sequence, and package used to access dept data
dept.idl: An IDL submitted to JavaIDL to generate helpers, holders, and so on

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DeptController.java: A server implementation of an object to manipulate dept data
DeptClient.java: A client wrapper to operate on DeptController references

Listing 50.1 shows the declarations the generated package specification would contain.

Listing 50.1. PL/SQL package containing functions for OLTP processing.

 CREATE OR REPLACE PACKAGE DeptPack AS     FUNCTION DeleteRow(     deptnoIn    IN NUMBER) RETURN NUMBER;     FUNCTION InsertRow(     dnameIn        IN CHAR,     locIn        IN CHAR,     deptnoOut    OUT NUMBER) RETURN NUMBER;     FUNCTION LockRow(     deptnoIn    IN NUMBER,     dnameOut    OUT CHAR,     locOut        OUT CHAR) RETURN NUMBER;     FUNCTION UpdateRow(     deptnoIn    IN NUMBER,     nameIn        IN CHAR,     locIn        IN CHAR) RETURN NUMBER;     PROCEDURE ReleaseLock; END DeptPack; / 

For performance reasons, as well as ease of use, the Database Application Support and Object Interface Generator separates data from operations. This separation enables applications to construct and manipulate the objects that contain the data directly and to access the ORB only when necessary. Listing 50.2 demonstrates this feature by showing the IDL generated for the DEPT interface.

Listing 50.2. Generated IDL for the DEPT transactions.

 #include "aisoci.idl" module DEPT {     struct DeptData {         long     deptno;         string     dname;         string      loc;     };       const long BLOCK_SIZE = 5; 

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 struct DeptBlock{            DeptData vals[BLOCK_SIZE];               long     numvals;        };        enum FilterType {LIKE, EQUALS};     interface DeptControl { DeptData openList(in DeptData filter, in FilterType mode) raises(AISOCI::AISOCIException);         DeptData fetchNext() raises(AISOCI::AISOCIException);               DeptBlock fetchBlock() raises(AISOCI::AISOCIException);         void closeList() raises(AISOCI::AISOCIException);         void insert(in DeptData dept) raises(AISOCI::AISOCIException);         void lockRow(in long deptno) raises(AISOCI::AISOCIException);         void delete(in long deptno) raises(AISOCI::AISOCIException);         void update(in DeptData dept) raises(AISOCI::AISOCIException);         void releaseLock() raises(AISOCI::AISOCIException);     }; }; 

Although this code looks complicated, it is generated for you and then is passed to the idltojava compiler to generate the supporting classes and interfaces. The Database Application Support and Object Interface Generator anticipates the output of idltojava and creates the object implementations and client wrappers appropriately. Suddenly, scott/tiger is a Web-enabled environment!

The source code in DeptController.java would contain the object implementation that communicates with the generated package. Listing 50.3 shows a portion of this class.

Listing 50.3. Java application code fragment that calls an Oracle package to lock a row.

 protected static final int OP_LOCK = 1; . . . protected static final int EMPNO_COL = 0; protected static final int ENAME_COL = 1; protected static final int JOB_COL = 2; . . . protected static final String LOCK_FUNC = "DeptPack.LockRow"; . . . public synchronized DeptModel lockRow(int deptno) throws AISOCI.AISOCIException { Vector     args = new Vector();           Vector     isOutput = new Vector();       Vector     quotes = new Vector();           Vector     outParms = new Vector();           DeptModel DeptOut = new DeptModel(); 

 continues 

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Listing 50.3. continued

 try {               AddAllArgs(OP_LOCK, args, isOutput, quotes, DeptOut);              outParms = DBConn.callFuncWithOutput(LOCK_FUNC, args, isOutput, quotes);             DeptOut.deptno = Integer.parseInt((String)outParms.elementAt(DEPTNO_COL));         DeptOut.dname = (String)outParms.elementAt(DNAME_COL);           DeptOut.loc = (String)outParms.elementAt(LOC_COL); }           catch (DBException e1) {           HandleDBException(e1);                  throw new AISOCIException(e1.getErrorCode(), e1.getErrorText());     }           catch (Exception e2) {               HandleJavaException(e2);                  throw new AISOCIException(0, e2.getMessage());           }     return DeptOut; } . . . 

The client wrapper to communicate with the server object is the only object that client applications use to communicate with the server implementation. This feature prevents developers from having to repeatedly perform tasks associated with accessing the ORB to obtain object references. All they need to do is ask once by using a few simple program calls. Listing 50.4, from the generated DeptClient.java class definition, demonstrates this point.

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Listing 50.4. Using simple program calls.

 public class DeptClient {     protected final static String                     CName = "DeptClient";     protected final static String                     CType = "DeptClient";     protected DEPT.DeptControl         ControlRef = null;     protected int                CRefID = 0;        public DeptClient(        AISORBClient Session) throws AISOCIException, Exception { try {                   ControlRef = Session.getObjectRef(Cname, Ctype, CRefID);         }         catch (AISORBException e1) {                   throw e1;         }               catch (Exception e2) {           throw e2;         }     } 

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