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Protocols

Why Protocols Matter​

The insanely fast growth and adoption of the World Wide Web would not have been possible without common protocols like TCP/IP and HTTP, which enable software from different vendors, servers at different providers, and browsers on different devices to seamlessly work together.

Dataspaces rely on the same principle: standardized protocols that form the foundation for all technical communication between participants. These protocols are what make dataspaces interoperable — any conformant implementation can participate, regardless of vendor, cloud provider, or deployment model.

The Three Protocols​

Interoperability is achieved by standardizing three distinct problem spaces. A practical way to remember the split:

DCP proves the parties. DSP proves the agreement. DPS drives the execution.

After that, the actual bytes move over wire protocols (HTTP, S3, MQTT, industrial protocols) between data planes, based on what was negotiated.

DCP — Decentralized Claims Protocol​

What it connects: Credential Service ↔ Credential Service

What it does: Establishes who you are in a decentralized way. DCP enables the exchange and verification of identity material and claims (verifiable credentials) so that policy checks can be evaluated against participant attributes.

When it runs: Before and during contract negotiation. When a participant requests access to data, the provider's system requests proof of the consumer's attributes. DCP governs how those proofs are assembled, presented, and verified.

Key characteristics:

  • Peer-to-peer credential exchange — no central identity broker
  • Supports selective disclosure — present only the attributes needed
  • Cryptographic verification — proofs can be checked without contacting the issuer

Specification: DCP v1.0.1

DSP — Dataspace Protocol​

What it connects: Control Plane ↔ Control Plane

What it does: Establishes what is being shared and under which rules. DSP covers three stages:

  1. Catalog discovery — a consumer queries a provider's catalog to find available data offerings and their terms
  2. Contract negotiation — the consumer and provider negotiate a contract agreement, with policies evaluated against credentials
  3. Transfer coordination — once a contract agreement exists, DSP coordinates the initiation and management of data transfers

When it runs: DSP is the primary protocol for the business interaction between two participants. It governs everything from "what do you have?" to "I agree to your terms" to "start the transfer."

Key characteristics:

  • Machine-to-machine negotiation — no manual contract drafting
  • Policy-driven — access and contract decisions are based on verifiable attributes
  • State machine — negotiations follow defined state transitions with clear outcomes
  • Based on web technologies — uses HTTPS, JSON-LD

Specification: DSP 2025-1

DPS — Data Plane Signaling​

What it connects: Control Plane ↔ Data Plane

What it does: Establishes how the agreed sharing is executed at runtime. DPS defines the signaling interface between the control plane (which decides) and the data plane (which executes):

  • Lifecycle signals: START, SUSPEND, TERMINATE over a shared data flow state machine
  • Registration: data planes register their capabilities (supported source types, transfer types) with the control plane
  • Capability-based selection: the control plane selects the right data plane for each transfer based on capabilities, placement, and health
  • Endpoint Data References (EDRs): for pull transfers, the data plane returns endpoint coordinates plus an access token

When it runs: After a contract agreement is established and a transfer is initiated. The control plane signals the data plane to start, and the data plane executes the actual data movement.

Key characteristics:

  • Decouples decision from execution — control plane and data plane can be deployed, scaled, and evolved independently
  • Supports multiple data planes — different planes for different protocols, regions, or workloads
  • Transport-agnostic — the actual data movement uses wire protocols appropriate for the data type

Documentation: DPS interface

How They Work Together​

When two participants interact to share data, the protocols execute in sequence:

1. DCP  — Identity verification between Credential Services
         "Are you who you claim to be?"

2. DSP  — Catalog discovery and contract negotiation
         "What do you have? Under what terms? I agree."

3. DPS  — Control Plane signals Data Plane
         "Start the transfer. Here are the parameters."

4. Wire — Data moves between Data Planes
         (HTTP, S3, MQTT, OPC-UA, etc.)

The sequence is not always strictly linear — DCP exchanges can happen during DSP negotiation (when policies require additional credential checks), and multiple DPS-signaled transfers can execute under a single DSP contract agreement. But the logical flow is clear: prove identity → agree on terms → execute the transfer.

Interoperability Validation: TCKs​

To ensure that different connector implementations actually interoperate, the ecosystem provides Technology Compatibility Kits (TCKs):

  • DCP TCK — validates Credential Service implementations against the DCP specification
  • DSP TCK — validates Control Plane implementations against the DSP specification

Running the TCK against your implementation is the fastest baseline check before debugging partner-specific configuration.

Standardization​

These protocols are not proprietary inventions. They are developed under Eclipse Foundation governance and build on international standards:

  • ISO/IEC 20151 — Dataspace concepts and characteristics
  • W3C DID Core — Decentralized Identifiers
  • W3C Verifiable Credentials — Credential data model
  • CEN-CENELEC JTC 25 — European standardization for dataspaces

The strategic implication: organizations adopting this stack are choosing interoperability over lock-in. The protocol surface is stable, vendor-neutral, and standards-backed.

Go deeper: IDSA Rulebook — Decentralization Principles | IDSA Rulebook — Planes

Related concepts: Trust and Governance | Decentralized Identity | Data Sharing Lifecycle

Components: Connector (Control Plane) | Identity Hub | Data Planes