Object-Oriented Software • How does it differ from procedural? • How is it similar to procedural? • Why has it become so popular? • Does it replace or supplement procedural? • What is the point? • Why bother? • Is it here to stay or gone tomorrow?
An Object-Oriented Program (OOP) • Is composed of a collection of individual units called objects which package data and functionality together, rather than of lists of instructions which act on external data. • Each object is capable of: • receiving calls from other objects to run methods, • executing its own methods, and • sending calls to run methods in other objects.
What is an Object in OOP? • An object is a softwareconstruct that bundles together data (state) and function (behavior) which, taken together, represent an abstraction of a thing, event, service, etc. • An object is an instance of a class. A class models a group of things, events, services, etc.; an object models a particular member of that group.
What is in a Class (or Object)? • A class contains attributes and methods. • Attributes describe state; methods perform actions. • Attributes may be Java primitives, or objects (strings, dates, arrays, other objects, etc). • Methods may be instance methods, which only work when the class is instantiated as an object, or static methods, which may be used independently of class instantiation.
Objected-Oriented vs. Procedural • Both types of language use structured programming logic; the logical architecture of a Java method will resemble that of an ILE RPG procedure. • The main difference is macro-architecture: • With OO, logic and data reside together in objects • OO design focuses on object relationships and interactions rather than code block relationships
Java Source and Object Files • Compilation Units (.java files) • With a main method • Without a main method • Java Bytecode (.class files) • Compilation-level class files • Nested class files
Glazers Interfaces Package • What is a Java package? • com.glazers.interfaces package • Five compilation units: • GetOpenPO – import open POs • GetInterCo – import intercompany transfers • GetOpenCO – import open customer orders • Function – class of static methods • LogMaker – class to make log object
Examples of Java Files Function.java Function.class GetOpenPO.java GetOpenPO.class ImportOpenPO.class
More Examples of Java Files LogMaker.java LogMaker.class LogMaker$PrintEnding.class LogMaker$PrintHeading.class LogMaker$PrintLine.class LogMaker$PrintMethods.class
Integration ETL Program Structure • Five Basic Steps • Open log file and database connections • Extract the result set from source system • Transform any data items • Load the data batch in target system • Close log file and database connections
What are the Objects? • Log Object • Database Connection Objects • SQL Statement Objects • Result Set Objects • BatchInsert Objects • String and Date Objects
The Code Environment package com.glazers.interfaces; import java.io.*; import java.sql.*; import java.util.*; import com.ibm.as400.access.*; import com.javaranch.common.GDate; import com.javaranch.common.JDate; import com.glazers.interfaces.*;
GetOpenPO Class and main public class GetOpenPO { public static void main(String args[]) { // Create an ImportOpenPO object ImportOpenPO impObj = new ImportOpenPO();
Full main method // Create an ImportOpenPO object ImportOpenPO impObj = new ImportOpenPO(); // Call the mainLine and receive its return code System.exit(impObj.mainLine(args[0],args[1], args[2],args[3],args[4],args[5]));
Comments // The main method for class GetOpenPO takes six parameters: // 1) Log File Directory Path (ex. Home/JavaApps/Manu) // 2) Oracle Database Name (SCPODEV, SCPOTEST, etc.) // 3) Oracle UserID // 4) Oracle Password // 5) AS/400 UserID // 6) AS/400 Password // After creating an ImportOpenPO object, these parameters are // passed to its mainLine method.
ImportOpenPO Class & mainLine class ImportOpenPO { public int mainLine (String dirPath, String oraSID, String oraUser, String oraPwd, String as400User, String as400Pwd) {
ImportOpenPO Code Structure • try [outer try/catch block] [start the log] • try [inner try/catch block] • open database connections • extract result set from source system • perform any data transformations • load data batch into target system • close database connections • catch [catch inner exceptions] • catch [catch outer exceptions]
Outer try statements try { // Create LogMaker object and begin logging LogMaker log = new LogMaker(dirPath,"OpenPO.log"); log.printHeading("Open PO Import Log"); // If run interactively, display running message System.out.println ("Open PO Import is running");
Inner try block job steps • Open database connections • Create Sql statement objects • Extract the result set • Loop throught the result set: • Extract the data items from result set object • Perform any data transformation • Set the data into the batchInsert object • Check error table for any rejects • If any rejects, print rejects to log • Close result sets and database connections
Connect to the iSeries // Register the AS400 JDBC Driver DriverManager.registerDriver(new AS400JDBCDriver()); // Create a properties object and connect to the database Properties as400Prop = Function.getAS400Prop(as400User,as400Pwd); conn400 = DriverManager.getConnection ("jdbc:as400://GLAZERS",as400Prop);
Connect to Oracle // Load the Oracle JDBC driver Class.forName("oracle.jdbc.driver.OracleDriver"); // Get the Oracle connection string String oraConnStr = Function.getOraConnStr(oraSID,oraUser,oraPwd); // Connect to the database server connOra = DriverManager.getConnection(oraConnStr); connOra.setAutoCommit(false);
Extracting the Result Set // Get the SQL statement to assign to the stmt400 sqlQuery string String sqlQuery = getSQL(); // Create a Statement object (stmt400) stmt400 = conn400.createStatement(); // Execute the SQL Select and obtain the ResultSet object (rs) rs = stmt400.executeQuery(sqlQuery);
The Batch Insert Prepared Statement // Construct the Insert Prepared Statement before entering the loop PreparedStatement sqlInsert = connOra.prepareStatement( "INSERT INTO INTINS_SCHEDRCPTS " + "(item, loc, scheddate, qty, expdate, ponum, " + "startdate, dateship, masterloadid, loadid," + "integration_stamp, integration_jobid)" + "VALUES (?,?,?,?,?,?,?,?,?,?,?,?)");
