The four phases you are referring to are:
- Readiness Phase
- Implementation Phase
- Go Live
- Post Go Live
Your specific query is about the third phase: Go Live.
Looking at your specific questions:
@aem_forum schrieb:
Two steps are described in this URL: Initial Production Migration and Incremental Top-Ups. What are we migrating in these? Code or Content?
Both migration types - initial and top-up migrations - are about content, not code.The difference of the two is about the migration methodology, not the coverage of what is being migrated. Simply speaking, initial migration is a full migration starting on a wiped repository while the top-up migration only covers diffs to the last migration run.
@aem_forum schrieb:
1. How and when is code migrated?
Source code (aka your application) needs to be refactored and updated to comply with AEM CS standards during the implementation phase. The "How" is covered by #1 in my initial post. The updated code will be pushed to Cloud Manager and Cloud Manager Pipelines will built the application and bake it into an AEM CS image.
@aem_forum schrieb:
2. Are we distinguishing between data and content?
No. In the context of AEM I don't see a differentiation between data and content. The most important differentiation here is between code and content. The key differentiator here is if it is part of a mutable (= content) or immutable path (= code) of the repository. (Please note: oftentimes both is being referred to as "content" because also your code will be stored on the content repository. A claim of AEM and it's predecessor CQ was that "Everything is content" which is somewhat changing with Cloud Services.) Also, I'm unable to find a reference to the migration of "data" in the documentation you linked so I'm unsure where this differentiation in your question comes from.
@aem_forum schrieb:
3. If so, How and when is each of these is migrated?
Your actual migration of production content will be part of the Go Live phase.
That being said, you will be running both, initial and top-up migrations, during your implementation phase already to gather data and experience as well as identify potential issues that you want to avoid during the actual go-live migration in this third phase.
I touched on the difference between both migration methods/steps in my initial response as well as my answer above to your question #1.
Hope this helps!