Series 9 · Orchestration architecture · 9.1
Keys to interoperability.
Formats, protocols and interface contracts that let a signature travel between systems.
A signature that can only be verified inside the system that produced it is not interoperable, and a signature that is not interoperable is worth less than it seems. Interoperability is not a feature added at the end: it is a design decision made at every layer. Unlike the previous series, this one sets out the principles behind how we think about Signing Flows; here the product appears as an example, not as an argument.
Four layers of interoperability
| Layer | What must be able to travel | How it is achieved |
|---|---|---|
| The document | The signature, its timestamps and its validation data. | Standard advanced signature formats, such as the ETSI PAdES profiles, up to the long term level. |
| Trust | Which providers and roots are valid. | Machine readable official trusted lists from multiple countries. |
| Services | Signature requests, timestamps, revocation checks. | Open protocols: the Cloud Signature Consortium interface, RFC 3161, OCSP. |
| Integration | Commands and events between the platform and other systems. | An interface described in a public contract, with signed events and operations that can be repeated without duplicate effects. |
Principles that do not change
- Standards before proprietary formats. If a standard exists, use the standard, even if it costs more.
- Independent proof. Interoperability is demonstrated by validating with third party tools, not declared.
- Explicit contracts. Every interface has a published, versioned specification, so that no one depends on implicit behavior.
- An exit is always possible. Everything that goes in must be able to come out, with its evidence, in open formats.
To interoperate is to accept that another system, one we do not control, must be able to understand and verify what we did.
Key points
Interoperability is built in four layers: document, trust, services and integration. At every layer the rule is the same: open standards, independent verification, explicit contracts and an exit that is always possible.