Java Agent Dynamic Bytecode Instrumentation Update
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Solution Overview
Problem
Existing Java Agent technologies do not allow for seamless updates without restarting the Java Virtual Machine (JVM) or the application, limiting the ability to deploy updates or roll back to previous versions while the application is running.
Innovation Solution
The solution involves dynamic bytecode instrumentation, where the Agent's code can be updated while it is locked and running within the JVM, allowing the updated Agent to be deployed without stopping the application or JVM, and enabling rollback to previous versions without restarting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Agent's code is locked in the JAR file to ensure integrity and proper loading by the Bootstrap Classloader, then the Agent can be reliably loaded and executed, but the code cannot be modified or updated without restarting the JVM
Solution Approach 1:
The patent segments the Agent code into two parts: the locked JAR file that is loaded by the Bootstrap Classloader for reliability, and a separate update mechanism that can modify the Agent code in memory. The JAR file contains the original locked code, while updates are applied through bytecode instrumentation that creates modified versions of the Agent classes without changing the original locked file.
Solution Approach 2:
The patent introduces an intermediary mechanism - a code transformer or instrumentation module - that sits between the locked JAR file and the running Agent code. This intermediary allows the original locked code to remain intact while enabling dynamic updates through bytecode manipulation, thus resolving the contradiction between locking for reliability and allowing updates for adaptability.
2Adaptability or versatility
If the JVM and Application are restarted to update the Agent, then the Agent can be updated to a new version, but the Application experiences downtime and service disruption
Solution Approach 1:
The patent makes the Agent code dynamic by enabling it to be updated in memory while the JVM and Application continue to run. The system dynamically loads new Agent code versions, applies bytecode transformations, and activates updated classes without requiring a restart, thus achieving dynamic updates with zero downtime.
Solution Approach 2:
The patent ensures continuous operation of the Application and JVM during Agent updates. The update mechanism is designed to work alongside the running system, allowing the useful action of the Application to continue uninterrupted while the Agent code is being updated in the background and activated.
3Adaptability or versatility
If the Agent code is made modifiable to allow updates, then the Agent can be updated dynamically, but the integrity and security of the Agent code may be compromised
Solution Approach 1:
The patent creates copies of the original Agent classes from the locked JAR file and applies modifications to these copies in memory. The original locked code remains unchanged and serves as the source of truth, while the copied and modified versions are used for dynamic updates. This copying mechanism preserves the integrity of the original code while enabling modifiable updates.
Solution Approach 2:
The patent uses an intermediary bytecode instrumentation layer that mediates between the locked original code and the modified update code. This intermediary ensures that modifications are applied systematically and safely, maintaining code integrity by preserving the original locked file as the authoritative source while enabling controlled modifications through the instrumentation layer.
Data Source
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AI summary
A method is disclosed herein for updating an Agent that is instrumenting the byte code of an application. The code of the Agent can be updated (112) by self-instrumenting its byte code without being disruptive to the application it is instrumenting. Each code version of the Agent is written in a particular Class acting like a Shim. Custom class loaders insure that there is no conflict between the reloaded classes.