Migration concepts

Enterprises often have their existing websites and systems, but they may wish to move onto Drupal. To accommodate this, Drupal has a core Migrate system to perform migration. Migration is then made easier through a common set of tools, practices, systems, and frameworks that offer repeatability, predictability, and consistency.

Migrate itself is built from a conventional ETL convention. This is a common design pattern in software engineering and not specific to Drupal. Drupal applies this concept through sources and destinations. Content is extracted from a source. Migrate’s tooling, including features within Drupal, processes that content into a raw data format. Finally, the raw data is loaded into the destination through serialization. This process maintains the foundational, underlying design of the Migrate system.

Migration brings a lot of complexity to both the sources and destinations involved in migrating content. Sources can be any content source...