Protocol

Overview

This protocol is responsible for endpoint and process control as well as data transfer, and provides functionality that enables transactions to be established as the nexus connecting each layer.

The core component group of this protocol, referred to as the Transaction Component, serves as the junction point among protocols defined in ODP. It communicates with each layer and perspective (Common Functionalities, Fundamental Protocols, and Complementary Protocols).

This protocol defines the following transaction management.

• Data transfer

  Provides functionality to transfer data from a data store endpoint in response to requests from a Data Consumer.

  To support data transfers across different data structures (structured / unstructured) and processing modes (synchronous / asynchronous), the data plane modules are logically classified into the following four types:

  • Web API Transfer Module

    A data plane module specialized for transferring synchronous structured data (e.g., Web APIs).

  • Stream Transfer Module

    A data plane module specialized for transferring asynchronous structured data (streaming data).

  • File / Bulk Transfer Module

    A data plane module specialized for transferring synchronous unstructured data (large files or bulk data).

  • Media Stream Transfer Module

    A data plane module specialized for transferring asynchronous unstructured data (real-time streaming data such as video or audio).

• Authentication and Authorization Integration

  Provides request-level authentication and authorization control in coordination with a credential issuance service and the Identity & Trust（L3）.

• Logging Records historical information and information required for clearing and payment (DCS) in coordination with Logging (Common Functionalities).

Abstract Normative Specification

Concepts and Roles

The following concepts are required for this protocol:

Concept	Description
Data Provider	An entity that sends data stored in a data store to a Data Consumer
Data Consumer	An entity that receives data from a Data Provider

Scope

This specification defines the Web API Transfer Module as a minimum implementation example.

Normative Requirements

• Data transfer within Open Dataspaces SHALL be performed through a data plane module.

  • Rationale: To ensure reliability and interoperability within Open Dataspaces.

• The architecture SHOULD maintain extensibility to support multiple data structures and transfer methods.

  • Rationale: Data distribution in Open Dataspaces involves diverse use cases, including structured / unstructured and synchronous / asynchronous patterns, and a single method cannot ensure interoperability and implementation flexibility.

• A data plane module MAY be used directly without employing the Control Plane Orchestrator.

  • Rationale: To enable ease of adoption and phased deployment, and to preserve flexibility in implementation and operation.

Non-functional / Cross-layer Requirements

• The module SHOULD integrate with the Identity & Trust（L3) to perform request-level authentication and authorization control.

  • Rationale: To ensure consistent access control, security, and interoperability across Open Dataspaces.

• The module SHOULD be capable of recording the minimum data required by Dataspace Complementary Services (DCS).

  • Rationale: To enable information linkage with DCS.

Message Types

The protocol handles the following types of messages:

Type	Sender ⇒ Receiver	Description
Request	Data Consumer ⇒ Web API Transfer Module; Web API Transfer Module ⇒ L3 Identity Component; Web API Transfer Module ⇒ Data Provider	A message sent to request data operations or authentication and authorization. It includes required header information and request parameters.
Response	Identity & Trust（L3）⇒ Web API Transfer Module; Data Provider ⇒ Web API Transfer Module; Web API Transfer Module ⇒ Data Consumer	A message sent in response to a request. It includes operation results, authentication or authorization validation results, tokens, or error information.

Message Format

Messages exchanged in this protocol consist of the following elements:

Element	Description
Header	Located at the beginning of the message and contains metadata required for communication control.
Payload	Located in the body of the message and contains the business data.

Protocol Flow

Communication Flow

Detailed Description of Each Communication

No.	Name	Sender	Receiver	Field	Description
1	Consumer Request	Data Consumer	Web API Transfer Module	Request fields depend on the target system specification. Refer to the specification published by the relevant Data Provider.	A message sent by the Data Consumer to the Web API Transfer Module to request a specific operation or information. Includes authentication information and request parameters.
2	Authentication and Authorization Request	Web API Transfer Module	Identity & Trust（L3）	Request fields depend on the Identity & Trust（L3）specification. Refer to the Identity & Trust（L3）specification.	A message sent by the Web API Transfer Module to the Identity & Trust（L3）to request authentication and authorization. Includes authentication information and request parameters.
3	Authentication and Authorization Response	Identity & Trust（L3）	Web API Transfer Module	Response fields depend on the Identity & Trust（L3）specification. Refer to the Identity & Trust（L3）specification.	A result message sent by the Identity & Trust（L3）to the Web API Transfer Module in response to a request. Includes authentication and authorization results, tokens, or error information.
4	Transfer Request	Web API Transfer Module	Data Provider	Request fields depend on the target system specification. Refer to the specification published by the Data Provider.	A message sent by the Web API Transfer Module to the Data Provider to request a specific operation or information. Includes authentication information (e.g., API key) and request parameters.
5	Provider Response	Data Provider	Web API Transfer Module	Receives either a successful response or an error response returned by the Data Provider. Refer to the specification published by the Data Provider.	A result message sent by the Data Provider to the Web API Transfer Module in response to a request. Includes API execution results or error information.
6	Consumer Response	Web API Transfer Module	Data Consumer	The successful response or error response returned by the Data Provider is, in principle, passed through as-is. Refer to the specification published by the Data Provider.	A result message sent by the Web API Transfer Module to the Data Consumer in response to a request. Includes API execution results or error information.

State Machine

This section describes the states handled by this protocol.

States

State	Description
Idle	Waiting for a request
Receiving	Receiving a request
Authenticating	Performing authentication
Authorizing	Performing authorization
Processing	Routing or proxying to the upstream system
Rejecting	Generating an error due to authentication or authorization failure
Responding	Returning a response (success or error) to the client

State Machine Diagram

Error Handling

This section describes the error handling used in this protocol.

Error Type	Description	Occurrence Timing	Handling
External System Error (Transparent)	Errors returned by an external system (4xx / 5xx specific to the external service)	Web API Transfer Module ⇒ External System	The external system response is returned as is.
Invalid Request	Request cannot be processed due to missing required headers or invalid values	Data Consumer ⇒ Web API Transfer Module	The request is validated and an error response is generated and returned if invalid.
API Key Error	API key validation failure	Data Consumer ⇒ Web API Transfer Module	The API key is validated within the module and an error response is generated and returned if invalid.
API Key Error (L3 Side)	API key validation failure at the Identity & Trust（L3）	Web API Transfer Module ⇒ Identity & Trust（L3）	The response from the Identity & Trust（L3）is returned as is.
Token-related Error (Authentication)	Access token invalid or expired	Web API Transfer Module ⇒ Identity & Trust（L3）	Based on the token validation result, an error response is returned as is if invalid or expired.
Insufficient Authorization	Access denied by authorization decision	Web API Transfer Module ⇒ Identity & Trust（L3）	Based on the authorization decision result, an authorization error response is returned as is.
Routing or Endpoint Error	Destination cannot be determined due to unregistered route or path/method mismatch	Web API Transfer Module	An error response is generated and returned.
External Connection Error	Failure to connect to L3 or external system, or invalid response received	Web API Transfer Module ⇒ Identity & Trust（L3）/ External System	Upon detecting connection failure or invalid response, an error response is generated and returned.
Timeout	No response received from L3 or external system within the defined time	Web API Transfer Module ⇒ Identity & Trust（L3）/ External System	Upon detecting timeout, an error response is generated and returned.
Internal Processing Failure	Processing cannot be completed due to internal exception	Web API Transfer Module	The exception is handled and an error response is generated and returned.