How does CORE use MyBatis for Legacy Applications?

Precision Mapping Between SQL and Java.

MyBatis is a lightweight open-source Object-Relational Mapping (ORM) Java component that enables the developer to work less easily with relational databases in a more flexible manner. MyBatis itself is simply a Java-to-SQL mapping tool and is ideally suited to any applications that need to manage data persistence without the complexity or overhead of a heavyweight ORM engine like Hibernate.

MyBatis does not take care of creating SQL on your behalf; rather you create your own SQL and then bind the results directly into your Java classes. This allows you to have complete control and freedom of database queries, but at the same time being blessed with the features of powerful mapping and code structuring.

MyBatis is a reliable and solid solution if you need a close control of how your application communicates with the database, when using Java.

MyBatis in the Modern Three-Layer Architecture

In the CORE Migrated Solution, MyBatis resides in the Data Access Layer, completely separated from the Presentation and Business Logic Layers. User interface components—developed in React, Angular, or WPF—communicate exclusively with REST APIs in the Business Logic Layer. Those APIs, service components, and workflow modules interact with MyBatis Mappers rather than embedding SQL directly.

This separation ensures that all SQL tuning, performance enhancements, and schema modifications occur in a centralized location without impacting the UI or business workflows. MyBatis becomes the single, consistent mechanism for interacting with the database, enabling easier maintenance, unit testing, and long-term extensibility.

How MyBatis Supports Modernized Batch Jobs

Legacy applications often rely heavily on batch processing, whether through PowerHouse QTP, COBOL jobs, Uniface batch routines, or Natural processes. During modernization, these jobs are migrated into Spring Batch Jobs, with each legacy “step” becoming a Spring Batch Step. MyBatis is used to read and write data throughout these batch flows.

Because MyBatis supports streaming, large result sets, and parameterized execution, it is ideal for high-volume data processing typical in batch workloads. The migrated solution behaves like the original system while leveraging modern frameworks that offer improved reliability, monitoring, and performance.

How MyBatis Supports Reporting Processes

Many legacy systems include reporting modules such as Quiz programs, COBOL print routines, or custom extraction scripts. In the migrated solution, MyBatis is used to retrieve the underlying data in a way that reproduces the logic, filters, grouping behaviour, and output characteristics of the original system.

Reports can be generated as flat files, PDFs, or integrated with tools like JasperReports depending on project requirements. MyBatis ensures that the data extraction logic is consistent, accurate, and aligned with the original business expectations.

What Happens to Operational Scripts During the Migration?

Legacy environments rely on scripting languages such as VMS DCL, Unix Shell Scripts, JCL, or Windows Batch files to coordinate jobs and processes. These scripts are migrated into Spring Boot scheduled components, CronJobs, or enterprise orchestration tools such as Jenkins. The new scripts and schedulers invoke Spring Batch jobs, file processing modules, and MyBatis-driven data interactions. This creates a modern operational environment that is fully observable, maintainable, and compatible with today’s DevOps pipelines.

Conclusion

MyBatis is a critical component of CORE’s modernization methodology. It provides a balanced approach that preserves SQL transparency while introducing structure, maintainability, and enterprise-grade reliability. By supporting REST APIs, batch jobs, reporting modules, and modern database interactions, MyBatis enables legacy systems to be faithfully reproduced in a modern, scalable, and fully maintainable architecture.

How MyBatis is Used

MyBatis is commonly applied in enterprise applications, web services, and Java backend systems where work teams should achieve accuracy and speed in dealing with the database.

MyBatis is used for:

SQL Mapping

You use either external XML files to write your SQL queries in, or you write the annotations directly in your Java code. With this, MyBatis connects those queries with your Java classes. MyBatis simplifies the development process with converting the rows of results into Java objects and back.

Data Access Layer

MyBatis is ideal for building a clean and maintainable data access layer. You can separate database logic from business logic, and work with plain old Java objects (POJOs) instead of relying on heavy ORM abstractions.

CRUD Operations

MyBatis makes common database operations like Create, Read, Update, and Delete (CRUD) simple and consistent. You can write custom SQL for each case and still benefit from clean code organization.

Integration with Spring

MyBatis integrates smoothly with Spring Batch and Spring Boot, which makes it a popular choice for teams using the Spring ecosystem. It works well with dependency injection, transaction management, and application context configuration.

MyBatis is a reliable and solid solution if you need a close control of how your application communicates with the database, when using Java.

Key Features of MyBatis

Custom SQL: You have full control over your SQL, which is great when you need to optimize queries or write complex joins.

Mapping Flexibility: You can map query results to Java objects manually or automatically, supporting nested objects and collections.

Annotation Support: Use annotations in Java classes instead of XML if you prefer a code-centric approach.

Dynamic SQL: Write flexible queries using MyBatis’s built-in scripting language to handle conditional logic.

Multiple Database Support: Works with any relational database that supports JDBC, such as MySQL, PostgreSQL, Oracle, or SQL Server.

Pros and Cons of MyBatis

Pros

More control over SQL: You write exactly what you need, which often results in better performance and more predictable behavior.

Lightweight and fast: MyBatis is minimal compared to full ORM frameworks and has a smaller learning curve for teams familiar with SQL.

Flexible mapping: Easily map complex result sets to custom Java classes, without jumping through hoops.

Good integration with Spring: Works well in Spring-based applications, which are common in the enterprise Java world.

Easier debugging: Since you are writing the SQL yourself, it is easier to trace issues and optimize queries when needed.

Cons

Manual SQL maintenance: You need to write and maintain all SQL manually, which can be time-consuming in large applications.

No automatic object relationships: Unlike Hibernate, MyBatis does not automatically handle things like lazy loading or cascading relationships.

More boilerplate: Even though it avoids ORM complexity, MyBatis still requires extra configuration (XML or annotations) for each query or mapping.

Limited abstraction: You are closer to the database, which is great for performance but can mean more work in terms of structuring and testing your queries.

Final Thoughts

MyBatis sits in a sweet spot between raw JDBC and full ORM tools like Hibernate. It gives Java developers fine-grained control over how they interact with the database, while still providing useful features like mapping and query organization. If you value performance, clarity, and hands-on control over your SQL, MyBatis is a strong choice.

MyBatis is especially useful in systems where SQL complexity is high, or where developers want to avoid the unpredictable behavior that can come from more abstract ORMs like Hibernate. And because MyBatis integrates well with Spring and other enterprise frameworks, it is a reliable option for serious backend development.