What is ECMA2?
One of the most important aspects of the sync engine is its ability to communicate with directories. There is some built-in connectivity to common directories, such as Active Directory, but there are more systems on the planet than Microsoft could possibly build connectors for.
In the sync engine, there is a public API that allows you to build your own custom connectors that work with the sync engine. Creating a connector is clearly a developer experience, but even as an IT-Pro you would need to understand these APIs when working with your developers to create custom connectors.
This section describes ECMA2 in detail from a theoretical detailed view and how certain scenarios should be solved with the framework. It does not contain sample code for connectors. There are several sites, for example on GitHub, where you can find sample code.
ECMA2 is available in FIM2010, MIM2016, and Azure AD Connect sync. The same connector can be used on all three systems.