bertails

"REST" is our industry's most successful collective delusion: everyone knows it's wrong, everyone knows we're using it wrong, and somehow that works better than being right.

We have a little bit of runtime checks in the Java projections but it's still tied to SHACL/SPARQL through the Jena library. We are exploring ways to keep using SHACL at scale for advanced data profiling, and also try to identify a subset of SHACL constraints which would be able to compile down to SQL constraints for validating directly against the data warehouse.

It is important in UDA for the data models to be part of the same knowledge graph as the data container representations and the mappings, and eventually the instance data too. Our metamodel Upper is strongly inspired from RDFS, SHACL, and OWL in that respect.

Exactly. In UDA, each Movie entity belongs to a specific business domain. Universality isn't an inherent truth, it's a social alignment within a group, useful only to the extent that it helps solve shared problems.

This does look interesting. Does the Ash Framework yield a knowledge graph? How good is it a cataloging existing data containers?

UDA does not believe in the existence of universal data entities. We embrace the idea that 2+ teams may have different opinions on how to represent the world. We are focused on the discovery of existing entities across systems and their reusability through extensibility. We believe that automation of the projections will be key for teams to align on defining some entities, where it makes sense.

We joke internally that Upper is like "RDF: The Good Parts".

> The whole point of GraphQL is to create a unified view of something, not to have 23 different versions of "Movie".

GraphQL is great at federating APIs, and is a standardized API protocol. It is not a data modeling language. We actually tried really hard with GraphQL first.

Great question. It really depends on the projection. For example, the projections to GraphQL and Java are mostly limited to what can be expressed there. But the projection to SHACL has access to all of SPARQL Constraints, which is what's used for the bootstrapping knowledge graph. We are looking into being able to do more runtime validation for data in the warehouse.

> I wonder how they deal with versioning or breaking changes to the model.

Versioning is permission to break things.

Although it is not currently implemented in UDA yet, the plan is to embrace the same model as Federated GraphQL, which has proved to work very well for us (think 500+ federated GraphQL schemas). In a nutshell, UDA will actively manage deprecation cycles, as we have the ability to track the consumers of the projected models.

> Of course, details on "Upper", PDM, and Sphere are well - missing, but at least I have concepts to focus on :)

Definitely coming soon ;-)

The price is in the 500+ domain graph services federated into our GraphQL enterprise gateway, which will all be exposed to Sphere through UDA. That's real.

> How does this relate to domain-driven design?

The "Domain" in `upper:DomainModel` is the same D as in DDD (Domain-Driven Design) as the D in DGS (Domain Graph Service).

> in DDD it's kind of expected that the same concept will be represented in a different way by each system

In UDA, those concepts would explicitly co-exist in different domains. "Being the same" becomes a subjective thing.

> Would also be more than happy to skip the whole GraphQL end of it.

Netflix benefits from a large GraphQL ecosystem with federation, which is why it's so central in UDA from day 1. But adding a projection to "REST" would be very easy.

UDA embraces the duplication of models: it's a fact of life in the enterprise. That is why "domains" are first-class citizen. We believe that good discovery capabilities will increase reusability of the domain models. Our next article will dive more into the extensibility capabilities of the metamodel Upper.

> It is fundamentally a business problem, rather than a technical problem, but it has impact on development speed, so it's secondarily a technical problem.

Yes it is a "fundamentally a business problem" but we believe it can be solved with technology. We think we have a more systematic way to adopt and deploy model-first knowledge graphs in the enterprise.

> But think about the red tape that introduces.

We are very intentional about UDA not becoming more red tape. UDA lives alongside all the other systems. There will never be a mandate for everything to be in UDA.

But we sure want to make it easy for those teams who wants their business models to exist everywhere, to be connected to the business, and to make it easy to be discovered, extended, and linked to.

(I'm one of UDA's architects.)