There are many circular dependencies between Zabbix components (the attached screenshot shows Levelized Structure Map of our product).

It is costly to maintain and add features to architecturally complicated codebase.

The purpose of this ZBX is to remove as much as possible of the incidental and unnecessary coupling between components early in the release cycle without affecting the functionality.

Few examples of unsound coupling:

• libraries including headers from agent and server;
• libraries calling functions from agent and server;
• functions defined or declared in the wrong places.

Most of these problems can be resolved by simple means: moving things around and adding a level of indirection through callbacks where it makes sense.