Front cover Modernizing IBM Eserver iSeries Application Data Access - A Roadmapmap Cornerstone Learn how to move your data definition of your applications from DDS to SQL Discover the ways to enhance your data access using SQL Understand the iSeries developers roadmap Hernando Bedoya Daniel Cruikshank Birgitta Hauser Sharon Hoffman Rolf André Klaedtke Warawich Sundarabhaka ibm.com/redbooks International Technical Support Organization Modernizing IBM Eserver iSeries Application Data Access - A Roadmap Cornerstone February 2005 SG24-6393-00 Note: Before using this information and the product it supports, read the information in “Notices” on page vii. First Edition (February 2005) This edition applies to Version 5, Release 3, Modification 0 of i5/OS, Program Number 5722-SS1. © Copyright International Business Machines Corporation 2005. All rights reserved. Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Notices . vii Trademarks . viii Preface . ix The team that wrote this redbook. ix Become a published author . xi Comments welcome. xi Part 1. Introduction and background . 1 Chapter 1. iSeries Developer Roadmap - The big picture . 1 1.1 Introduction to the iSeries Developer Roadmap . 2 1.1.1 Why a roadmap. 2 1.1.2 Why care about it . 3 1.1.3 The goal . 4 1.2 What is in the roadmap . 4 1.2.1 Better tools . 5 1.2.2 Better user interface . 6 1.2.3 Better architecture. 7 1.2.4 Better portability . 8 1.2.5 Better scalability . 8 1.3 What is in this book . 9 Chapter 2. Why modernize with SQL and DB2 UDB for iSeries . 11 2.1 Background . 12 2.1.1 A short look at the history of SQL . 12 2.1.2 The main parts of SQL . 12 2.2 Reasons to modernize . 12 2.2.1 Standard compliancy . 12 2.2.2 Openness . 13 2.2.3 Performance . 13 2.2.4 Available skills. 15 2.2.5 Functionality . 16 2.2.6 Data integrity. 17 Part 2. Data definition. 19 Chapter 3. Approaches and options . 21 3.1 Data definition considerations . 22 3.2 Accessing the database data . 23 3.2.1 Native record level access . 23 3.2.2 Data access with SQL. 23 3.3 Methodology for the modernization. 25 3.3.1 Reverse engineering DDS to SQL DDL (stage 1). 25 3.3.2 Creating I/O modules to access DB data (stage 2). 26 3.3.3 Moving business rules into the database (stage 3). 26 3.3.4 Externalizing data access (stage 4) . 26 Chapter 4. Modernizing database definitions. 29 4.1 Reverse engineering DDS to SQL DDL . 30 © Copyright IBM Corp. 2005. All rights reserved. iii 4.1.1 Classify the existing environment . 30 4.1.2 Establishing a list of all DDS files to be converted . 31 4.1.3 Establishing naming conventions for SQL objects . 32 4.1.4 Converting the DDS to SQL DDL . 34 4.1.5 Reviewing the generated SQL DDL . 36 4.1.6 Creating the new DB2 schema on the iSeries server . 40 4.1.7 Create all existing DDS logical files over the new SQL tables . 43 4.1.8 Migrate data and test existing programs. 46 4.2 Comparing the SQL objects and the DDS files . 48 4.2.1 SQL tables compared with physical files. 48 4.2.2 SQL indexes compared with keyed logical files . 48 4.2.3 SQL views compared with logical files . 49 4.2.4 SQL data types . 49 4.3 SQL system catalogs: Definitions . 50 4.3.1 SQL system catalogs: Example . 52 4.4 Partitioned tables . 53 Part 3. Data access . 55 Chapter 5. Creating I/O modules to access SQL objects . 57 5.1 Introduction . 58 5.2 Establish naming conventions. 58 5.3 Create SQL views based on business requirements . 59 5.4 Create service programs to access data from the SQL views . 62 5.5 Convert legacy programs to use service programs. 63 Chapter 6. Moving business rules to the database . 65 6.1 Database normalization . 66 6.2 Referential integrity . 67 6.3 Constraints . 67 6.4 Constraint coexistence considerations . 68 6.5 Column-level security . ..