11. Release Handling

11 Release Handling

11.1 Release Handling Principles

An important feature of the Erlang programming language is the ability to change module code in runtime, code replacement, as described in the Erlang Reference Manual.

Based on this feature, the OTP application SASL provides a framework for upgrading and downgrading between different versions of an entire release in runtime. This is called release handling.

The framework consists of:

• Offline support - systools for generating scripts and building release packages
• Online support - release_handler for unpacking and installing release packages

The minimal system based on Erlang/OTP, enabling release handling, thus consists of the Kernel, STDLIB, and SASL applications.

Release Handling Workflow

Step 1) A release