Federated architectures failed to live up to their promise because software is an opinion. The consequence: No matter how often vendors bandied about terms like "metadata," it was of no help when the corresponding data fields in different best-of-breed systems were semantically different -- when they meant something similar but not exactly the same.
When that happened -- for example, let's say one system stores color as RGB values, another as Pantone codes, a third with plain-language words like "red" -- metadata mappings didn't help because the source system data was a round peg, and only some fairly nasty code could hammer it into the square hole that was the target system.
Then there's the matter of redundant business logic. Because best-of-breed systems weren't designed to respect each other's boundaries, they have overlapping functionality. Magic pipe or no magic pipe, IT either ripped the logic out of one system, replacing it with a call to the other system -- an ugly process that meant tinkering with core code -- or used brute-force techniques to keep the redundant logic synchronized.
(Time for the screen image shimmer and harp again, as we return to the present.)
You don't hear the phrase "federated systems" very much anymore because in most situations they're a good bit harder to make work than the alternative, which is to use an ERP suite as the heart of the enterprise technical architecture. It's in the middle -- the master repository.
IT will implement satellite systems when the ERP suite's module just doesn't do what the business needs. The satellite systems don't communicate directly through a magic pipe, though. They all feed the ERP suite -- the single source of truth that then updates any other satellite systems as necessary. This by itself makes ERP guru-hood valuable. Now let's add two new trends to the mix.
The first is that there are no IT projects anymore -- none. Every project is about changing how the company operates, not delivering software that meets the specs. Business change usually involves software change, but as an enabler for the new way of working, not as the endpoint of the effort.
The end of IT projects will drive dawning awareness of the best Agile variant nobody ever heard of: Conference Room Pilot (CRP), the only application methodology that easily supports business change as well as software delivery. Here's how it works: The project manager reserves a conference room for a month or so, locking the ERP gurus in it with the company's smartest and most knowledgeable business managers and users. Everyone has access to the ERP system in its current configuration (or, if this is a new installation, in plain vanilla).
Also in the room is a big stack of test cases -- real-world situations the system will have to handle.