OK. This is a huge question with more than one correct answer, perhaps not suited for a simple Community thread (as opposed to working offline with someone who specializes in such things).
First thing to clarify is you will not be able visualize real-time data outside of Marketo. Marketo doesn't have a streaming API where events can be fed, over a persistent connection, to another system. Rather, data must be extracted periodically and imported into another system.
The "period" in "periodically" may in theory be as short as every hour, though it typically is most efficient to do a single daily export. But regardless of the frequency, the method is always a scheduled pull from Marketo. There are some vendors who perform the scheduled import-exports for you, which may make it seem like they have a direct/special connection from Marketo to your system, but they don't — they're using the same method under the hood.
Next, realize the Marketo API endpoints used differ greatly depending on exactly what data you need. Flat Person fields, Program Member data, Activity Log entries, and — very soon — Marketo Custom Object records can be exported to a CSV (generated on Marketo's side) and downloaded as a single file. Scheduling the CSV export is still a multi-step process, though.
In contrast, mirroring your Marketing Activities tree (including Program and Channel metadata), getting deeper information about LP and Email assets, and exporting List members use a very different set of APIs which are paginated (meaning you need to open a new connection for every, say, 300 records of a certain type). Also, those APIs aren't great at getting only updates since a current date, so there is more delicate work that needs to be done to have an up-to-date representation of Marketo.
There are also questions to answer about how to merge activities that were once anonymous as they become known. (Remember, a person's Activity Log is not static; it's continually backfilled, so Day 1 may look a certain way on Day 2, but when you check on Day 10, Day 1 can have tons more data.) And how to store each change to program status — choosing the right back end database & database schema is important. And how to merge assets whose name changes over time. That's not even getting into the question of which BI tool!
And the above is a very superficial treatment of the topic. 🙂
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