Legacy Software Modernization
G&G’s AS400 iSeries RPG, ILE, Synon, COBOL Programmers-Developers helping in AS/400 Modernization & Migration
The System i (including AS400, iSeries) platform is one of the most reliable and cost effective platform. Its stability and features have made it a mainstay in many corporations, running some of the world’s most demanding applications. Still, businesses with System i RPG applications often find that supporting their applications is increasingly costly and cumbersome with an uncertain future. G&G’s RPG, ILE, Synon and COBOL programmers and developers are engaged in migration and modernization of AS/400 applications. Legacy modernization projects are performed to resolve the current challenges facing organizations operating critical business functions on legacy platforms.
The reasons businesses want to migrate are as follows:
- To reduce the costs of supporting their iSeries RPG application software and hardware
- To move away from RPG, with its shrinking pool of resources, to a modern approach using .Net
- To integrate .Net capabilities with their iSeries
Companies have the option to choose from a wide variety of target architectures like non-web based client server architecture, open source frame works and technologies such as PHP and others. The most common target platforms are that of Microsoft .NET and Java.
The Windows and Internet environment and the latest programming languages available in .NET provide modern Web/Windows-based interfaces to the legacy systems. The end result is a robust, modern and intuitive application running on the Windows platform with an iSeries application and database providing data processing support. The advantage of this approach is to harness the performance capabilities of the iSeries, while taking advantage of the power of Windows and .NET.
User Interface – Screen Modernization of AS400 / iSeries RPG Applications
New interfaces are the most visible result of most modernizations. There are mainly two types of screen modernization approaches:
Screen Scraping: The screen-scrapping concept gained popularity in the iSeries world way back in the early 90’s when developing scalable client server applications for the iSeries was quite difficult. It was the most effective method for putting a front end on iSeries applications in MS Windows. Over time, the screen scraper vendors evolved to a new model. The 5250 I/O stream between your application and your browser was intercepted, analyzed and mapped to new web based screen components. Although this approach was quite popular several years ago it is no longer a common approach as it is very complex to maintain and inflexible.
True Web Pages: This approach creates true web pages (ASP, JSP, PHP) by analyzing display files and RPG application code and creating true web pages that run in a web (or client server) environment such as Microsoft .NET or Java. These use web and application servers just like any other newly developed applications. Their advantage is they are flexible, highly maintainable and use standard technologies and development techniques that can be maintained by any developer.
Converting Synon, CL, RPG Application Programs
Existing RPG programs and iSeries applications like CL, COBOL and Synon applications have a dramatically different structure than modern object oriented applications in C#, Visual Basic and Java. While the new architecture may still contain some artifacts of the old architecture, it is typically vastly improved and more maintainable.
DB2/400 Database Conversion
Several options exist for database conversion:
Native Relational Database: Here the native DB2/400 schema is mapped to a true relational database schema. Existing physical and logical files are mapped onto appropriate relational database tables and mapping relationships using primary and foreign keys. During this conversion a mapping of the DB2/400 to relational model is kept to which acts as a guide when the appropriate SQL codes are generated.
As part of this conversion process, the appropriate database creation code (DDL) would automatically be generated. This DDL could then be run to create the new relational database prior to transferring of data from the DB2/400 database to the new relational database.
Database Gateway: In some cases, it may be desirable to leave the DB2/400 database intact, and provide a gateway that interfaces with the iSeries database on one side, and provides a full relational access model (using standard SQL statement) on the other. This enables modernized applications to access the DB2/400 database without any modifications to the database – leaving it running on the iSeries and using it as a powerful database server. The advantages of this approach are several:
- You continue to harness the power and stability of the iSeries as a database server
- No changes to the database or reloading are required, eliminating any downtime during conversion
- The modernized RPG code can continue to use standard iSeries data access methods such as record level access to data.
System i developers considering migration – conversion to Unix, Unix & Windows
Customers worldwide are evaluating contemporary and scalable modernization approaches for iSeries servers. Through migration to HP systems running UNIX, Linux and Windows, organizations can utilize open computing platforms that can increase their business performance, agility and competitiveness while reducing legacy operating costs.