Enabling Applications written for transactional databases to work with Oracle databases without source level changes

Transcription

1 ISAM TO ORACLE RDBMS MIGRATION Enabling Applications written for transactional databases to work with Oracle databases without source level changes White Paper M ERTECH D ATA S YSTEMS, INC SW 107 th Ave, Suite 200 Miami, Florida 33176, USA

2 This document is for informational purposes only. MERTECH MAKES NO WARRANTIES, EXPRESSED OR IMPLIED, IN THIS DOCUMENT. Copyright 2002 Mertech Data Systems, Inc. All rights reserved. Oracle is a trademark of Oracle Corporation. MS SQL Server is a trademark of Microsoft Corporation. Btrieve and Pervasive.SQL are registered trademarks of Pervasive Software. Other trademarks and trade names mentioned herein are the property of their respective owners.

3 CONTENTS I. INTRODUCTION...1 BACKGROUND...1 A NEW APPROACH...1 II. A CASE FOR RELATIONAL DATABASES...2 III. DILEMMA FOR BTRIEVE DEVELOPERS AND USERS...2 ISSUES FACING CORPORATE USERS...2 ISSUES FACING BTRIEVE DEVELOPERS...2 MERTECH S SOLUTION...3 BTR2SQL DATA MIGRATION TOOL...3 MERTECH ISDBC DRIVER FOR ORACLE...3 IV. THE MIGRATION PROCESS...4 STEP 1: DATA MIGRATION USING BTR2SQL...4 Identify the File.DDF file and the Specific Data to Migrate... 4 Migrating the Data... 5 STEP 2: REPLACING THE PERVASIVE DLLS WITH MERTECH DLLS...6 DRIVER MECHANICS...6 V. BENEFITS OF USING MERTECH S SOLUTION...8 BENEFITS TO DEVELOPERS...8 BENEFITS TO CORPORATE USERS...9 VI. CONTACT INFORMATION...9 APPENDIX SUPPORTED PERVASIVE-API FUNCTIONS...10

4 I. INTRODUCTION The objective of this white paper is to familiarize the reader with Mertech Data System s latest product offering a set of data migration tool and high-performance database drivers that allow quick and efficient migration of applications developed around Pervasive Software s Btrieve transactional engine to an Oracle backend. B ACKGROUND The Internet revolution has underscored the importance of making data available reliably and at a high speed to an ever-growing user base. Corporations continue to consolidate their data into single, corporate-wide database so that information about its customers, products, and market can be easily extracted and manipulated and at the same time allow customers and mobile work force to update and retrieve information anytime, anywhere These new, data-intensive demands of today s businesses requires a database server that is robust, is scalable, gives excellent response time in extracting and manipulating data, has great disaster recovery features and above all provides excellent security features and guarantees 24X7 availability. IDC estimates that SQL-based relational databases hold a 90% market share. In the Windows market, Oracle and Microsoft have 80% of the market share while in the Unix market, Oracle alone has 67% of the market share Relational or SQL (Structured Query Language) based databases from companies like Oracle, Microsoft, IBM and others meet these criteria. Indeed the features of these databases, combined with the marketing might of the software heavyweights have helped make relational database engines a de facto standard in the business application market. Companies using or developing applications written around the Btrieve data manager, which utilizes the Index Sequential Access Method (ISAM) or transactional approach to data storage and retrieval, find that moving their applications to the industry leading SQL database engines presents significant challenges. There are two obvious migration paths; 1) rewriting entire applications written around the transactional paradigm to support relational approach using SQL or set paradigm 2) write a new application from scratch. Both require significant resources and time and may not be feasible for many companies. A NEW A PPROACH Mertech is offering a third option that is both flexible and cost efficient to handle this migration issue. Mertech s new product offering will allow developers using ISAM-based transactional data sources to deploy their applications with Btrieve and newer Pervasive.SQL engines as well as with Oracle back-end without requiring recompilation or code rewrite. This means that an application currently working exclusively with Btrieve or Pervasive engines will be able to work with an Oracle database server in very little time, following a few easy steps! Mertech already offers a similar solution for the DataFlex market. Over 1000 companies on five continents have saved millions of dollars by using Mertech s solution. Mertech s ISAM To SQL Database Connectivity Driver for Btrieve(R) to MS SQL Server connectivity is explained in depth, beginning with a holistic look at how the solution works followed by a detailed analysis of its major components. 1

5 II. A CASE FOR RELATIONAL DATABASES The case for relational databases can be made on two fronts. First, the relational model for data storage and retrieval has proven to be superior at handling large amounts of data and turning that data into useful information without requiring special programming techniques. The reason for that superiority is the Structured Query Language (SQL). This relatively simple language allows complex data manipulation using only a few simple commands. Second, because of that superiority and simplicity as well as the standardization of the SQL language, almost all major software providers support SQL-based back-ends through Open Database Connectivity (ODBC), OLEDB or native programming interfaces. Companies switching to a SQL database not only get a robust, more efficient enterprise-wide data solution, but they also get access to a variety of tools and applications that work seamlessly with these SQL databases. III. DILEMMA FOR DEVELOPERS AND USERS I SSUES F ACING C ORPORATE U SERS To meet the stringent demands placed on database servers due to data consolidation, corporate users of database applications want the power, scalability and reliability offered by industry leading relational database engines. Corporations who have their data scattered over disparate databases often face difficulties in using business analysis, reporting and other business tools that are crucial from a corporate perspective. In many cases, companies may already be using an SQL-based database with newer applications and yet still may have some applications using Btrieve and Pervasive.SQL transactional data sources. This lack of standardization often presents integration issues to the IT department. Applications can be modified or rewritten to support a single corporate database standard. However, this can be an expensive and time-consuming option. In an effort to consolidate data quickly, companies maybe willing to pull the plug on their existing applications and opt for an off-the-shelf solution that integrates well with mainstream database engines. But adopting a new application is more than just buying a piece of software and installing it. IT departments have to contend with implementing the new product, testing it, rolling it out to select users, further testing, Q&A, and, finally, deploying it. And then there is the cost associated with retraining end-users on the new software. I SSUES F ACING D EVELOPERS The developer is faced with two hurdles in the SQL-standardizing market. First, their already established customers often want the ability to run their applications on a mainstream database server. Second, to expand their customer base these developers need to find new customers. Since 90% of the customers buying database servers chose an SQL-based solution, it is imperative that application 2

6 developers who are looking to attract new customers support RDBMS database servers. These hurdles have left the developers with only one option roll up their shirtsleeves and learn to program with SQL and potentially recode thousands of lines of code to accommodate the set-based paradigm of SQL. Not an easy task! M ERTECH S SOLUTION Recognizing the enterprise demand for Oracle and the hurdles that developers must overcome to transition from and ISAM to set-oriented data sources, Mertech has created a family of middle-ware applications designed to: Mertech s solution allows developers to still effectively program with their transactional API, thus keeping the same sourcebase for multiple back-ends Alleviate the costs associated with migrating applications working against existing Btrieve or Pervasive.SQL transaction data sources to Oracle databases Provide developers with a cost-effective, efficient, and platform independent solution to use their existing code with Oracle database servers Create the opportunity for the developer to leverage existing applications with an Oracle backend immediately Accomplish all of the above without compromising the stability or speed of the application. Mertech accomplishes these objectives with a family of high performance database drivers designed to translate calls made to the Btrieve and Pervasive.SQL transactional API into SQL statements that work with the target SQL-backend. With this solution, Mertech has successfully provided both corporate users and developers of applications based on ISAM-based engines, like Btrieve and Pervasive.SQL engines, the most cost-effective and efficient method to work with an Oracle database. Apart from significant cost and time savings, developers can use this efficient solution to make their applications database independent they can deploy the same application using Btrieve engines, or new versions of Pervasive Software s Pervasive.SQL engines or with Oracle. No source code changes are needed! BTR2SQL DATA M IGRATION T OOL To handle migration of existing Btrieve file structures and data to Oracle, Mertech provides a database migration tool to simplify the data migration, table, and index creation process. The tool, BTR2SQL, is an integral part of the product bundle and is included with the purchase. BTR2SQL is a standard 32-bit application that runs on the Microsoft Windows platform. M ERTECH ISDBC DRIVER FOR O RACLE Mertech's ISDBC Driver for Oracle uses Oracle's Oracle Call Interface (OCI) for communicating and accessing the Oracle database. Mertech s Driver communicates directly with the Oracle server through Oracle s network interface SQL*Net. Mertech s Driver supports Oracle version 8.0x and higher 3

7 IV. THE MIGRATION PROCESS The entire migration process of a Btrieve -based application to an SQL back-end can be broken down into two distinct steps: 1. Set up the target backend and migrate data from Btrieve to the SQL data source using BTR2SQL 2. Replace wbtrv32.dll and wbtrv7.dll with Mertech s dynamic link library of the same name The illustration below, The Mertech Road to Migration, depicts how these components work together to achieve the migration. S TEP 1: DATA M IGRATION U SING BTR2SQL Before the drivers can be used, the existing data must be converted into SQL. This is accomplished by using BTR2SQL migration tool. To start the migration process, the user Identifies the existing file.ddf files to migrate Chooses which data files will be migrated, Initiates the migration process Identifying the File.DDF file and the Specific Data to Migrate BTR2SQL works with the.ddf files. BTR2SQL allows the user to locate and select the.ddf file and display the file entries in a file list dialog. The user can select any number of files to migrate by highlighting the file names (as illustrated in Picture 1). 4

8 Picture 1 The user can select one file or multiple files from the list dialog. Migrating the Data After selecting the files, the user can perform a number of operations such as Convert Database, which creates a corresponding table in the target SQL backend and moves the Btrieve data to the newly created table. The Convert Database option brings up another dialog that allows the user to set migration options (Picture 2 below). These selections are stored in auxiliary files, called the.int (intermediate) and the.td (table definition) file. Picture 2 Users can select whether they want to fetch a record at a time or fetch a set of record in one network roundtrip. 5

9 The physical migration of data is quick and efficient. BTR2SQL is designed to move data at very high speeds using native tools for fast data loading for example, SQL*Loader for Oracle. BTR2SQL also provides the ability to generate SQL scripts to create tables and indexes outside the tool. A driver prefix is added to the file name, ORA_BTR for Oracle, to identify that the files have been migrated to the target backend. STEP 2: REPLACING T HE P ERVASIVE DLLS WITH M ERTECH DLLS Mertech s database drivers are dynamic link libraries that replace or work side-by-side 1 with the Pervasive dlls. Mertech s product bundle provides Oracle enabled w3btrv7.dll and wbtrv32.dll, which can replace the Pervasive dlls of the same name. D RIVER M ECHANICS To understand how the various components interact with each other, the migrated application can be broken down into four separate layers. 1. The application code (VB, Delphi, C/C++ etc) 2. The Pervasive API layer 3. Mertech s Internal API layer 4. SQL Native API layer This is depicted in Illustration 2. 1 The developer does not always have to replace the drivers. Rather, they can make explicit calls in the source code to the Mertech Data driver rather than the Pervasive.dll. This provides the developer the opportunity to work with both data sources (i.e., if migration will take some time, the application can work on the Btrieve data source for production and the SQL data source for testing). 6

10 Illustration 2: Application Layers Layer 1: The Application Code There is no change required in the application if the developer simply replaces the Pervasive dlls with the Mertech dlls of the same name. However, the developer can access both Oracle and Pervasive data sources from the same application by using the same Mertech driver but deployed under a different name. In that case the developer will make the following change to the source code to call Mertech s drivers. For example, the following changes will be made to an application written in Visual Basic: Declare Function BTRCALL Lib "ora_btr.dll Alias "orabtrcall" (ByVal OP, ByVal Pb$, Db As Any, DL As Integer, ByRef Kb As Any, ByVal Kl, ByVal Kn) As Integer 7

11 Using C/C++ Programs The "C" programs using Pervasive s Btrieve or Pervasive.SQL s wbtrv32.dll will have to be linked to use ora_btr.dll (.lib). In a global file, the following has to be defined for correct function mapping: #define BTRCALL orabtrcall Layer 2: The Pervasive API Calls All applications using Btrieve s transactional engine use BTRV() function calls. These functional interfaces reside in Pervasive s dynamic link libraries, wbtrv32.dll or w3btrv7.dll. The application will make its usual calls to the transactional API functions passing Btrieve function codes. Layer 3: Mertech s Internal API Because Mertech s Driver has replaces the Pervasive s dlls, calls to the Pervasive API (from the application) are trapped and translated into SQL statements and sent to Oracle using OCI calls. Layer 4: SQL Back-End Native API With a translated set of commands to the data source, the application can now transparently interact with the SQL back-end through the native API calls in Mertech s drivers. Furthermore, the SQL statements generated by the drivers are optimized for the best possible performance. V. BENEFITS OF USING MERTECH S SOLUTION As described in this white paper, Mertech s product provides a number of critical benefits for both businesses and developers. B ENEFITS TO D EVELOPERS Cut down implementation time run existing application against Oracle databases immediately. Continue to program in a familiar environment because no changes are required to the source code, the developer can continue to program in Btrieve and Pervasive.SQL transactional API using their existing development tools and then deploy on multiple databases. Open doors to new markets With Mertech s approach, the developer will be able to continue to support Btrieve -based applications and still have flexibility to offer solutions for multiple back-ends on multiple Operating System platforms: from Windows to mainframes running Oracle. Speed and reliability every developer is concerned about the speed and efficiency of applications. With Mertech s highperformance drivers, all translated functions are optimized to work as effectively as possible with an Oracle backend. 8

12 B ENEFITS TO C ORPORATE U SERS Easy Migration the fact that the Btrieve -based applications can work concurrently with Oracle and Btrieve databases ensures that customers and employees won t be severed from the data while the migration moves forward Corporate wide data consolidation with the scalability provided by Oracle, data from Btrieve engine can now be moved to a single corporate wide database. Faster reporting by using Crystal Reports or other reporting tools directly with Oracle. Integration with other applications access data from other applications. Zero retraining cost users can continue to use familiar applications. VI. CONTACT INFORMATION If you would like to know more about Mertech s products, please visit our web site at or contact us at: Corporate Headquarters: Mertech Data Systems, Inc SW 107 Ave. Suite 200 Miami FL USA Tel: +001 (305) Fax: +001 (305) sales@mertechdata.com Brazilian Subsidiary: Al. Rio Negro 1105, cj 63 Alphaville Barueri, SP Brazil Tel: +55 (11) / Fax: +55 (11) mertechbrasil@mertechdata.com 9

13 APPENDIX 1 S UPPORTED P ERVASIVE-API FUNCTIONS Constant Status Version B_OPEN Implemented2 Release 1 B_CLOSE Implemented Release 1 B_INSERT Implemented Release 1 B_UPDATE Implemented Release 1 B_DELETE Implemented Release 1 B_GET_EQUAL Implemented Release 1 B_GET_NEXT Implemented Release 1 B_GET_PREVIOUS Implemented Release 1 B_GET_GT Implemented Release 1 B_GET_GE Implemented Release 1 B_GET_LT Implemented Release 1 B_GET_LE Implemented Release 1 B_GET_FIRST Implemented Release 1 B_GET_LAST Implemented Release 1 B_CREATE B_STAT Implemented Release 1 B_EXTEND B_BEGIN_TRAN Implemented Release 1 B_END_TRAN Implemented Release 1 B_ABORT_TRAN Implemented Release 1 B_GET_POSITION Implemented Release 1 B_GET_DIRECT Implemented Release 1 B_STEP_NEXT Implemented Release 1 B_STOP Implemented Release 1 B_VERSION Implemented Release 1 B_UNLOCK Implemented Release 1 B_RESET Implemented Release 1 B_SET_OWNER B_CLEAR_OWNER B_BUILD_INDEX Ready to be implemented Release 2 B_DROP_INDEX Ready to be implemented Release 2 B_STEP_FIRST Implemented Release 1 B_STEP_LAST Implemented Release 1 B_STEP_PREVIOUS Implemented Release 1 B_GET_NEXT_EXTENDED Implemented Release 1 B_GET_PREV_EXTENDED Implemented Release 1 B_STEP_NEXT_EXT B_STEP_PREVIOUS_EXT B_EXT_INSERT B_SEEK_PERCENT Implemented Release 1 B_GET_PERCENT Implemented Release 1 KEY_BIAS B_CHUNK_UPDATE B_EXTENDED_STAT S_WAIT_LOCK Implemented Release 1 S_NOWAIT_LOCK M_WAIT_LOCK M_NOWAIT_LOCK NOWRITE_WAIT 2 Functions not implemented are either not required anymore or are not considered critical at this time. The calls can still be made to the driver but no value or a fixed pre-defined value might be returned. 10