Previously in DBL Talks, we examined “I/O Basics” and “The Select Class.” Episode 3 delves into “I/O Hooks,” a powerful feature that allows you to intercept and extend standard I/O operations like READ and WRITE without modifying your core application logic. 

DBL Talks is an educational video podcast series that explores key DBL concepts through focused, code-driven discussions. Each episode walks through real examples, explains the “why” behind the syntax, and shows how the pieces fit together. The goal is to make it easier for developers to understand how Synergy works under the hood and how to use it effectively in real-world applications.

Episode 3 investigates how I/O hooks enable you to execute custom logic before and after file operations, making them ideal for logging, validation, and other cross-cutting concerns. You’ll learn how to create your first hook, attach it to a file channel, and scale the approach using global hooks across your application.

We cover

• What I/O hooks are and how they work in Synergy DBL
• Intercepting READS operations with pre- and post-operation hooks
• Creating a custom LoggingIOHooks class
• Attaching hooks to file channels
• Using global hooks with SYN_GLOBALHOOKS_OPEN
• Applying hooks selectively based on filename or open mode
• Performance considerations and best practices for hook implementation

Throughout the episode, we show practical code examples and explain how these pieces work together in real Synergy DBL applications. You’ll find links to the example code and relevant documentation in the video description to help you follow along or explore topics further.

Watch DBL Talks Episode 3: I/O Hooks on YouTube.

Coming Next

In Episode 4 of DBL Talks, we’ll discuss working with ISAM utilities.

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