a2a_http_server

Tip

WASM-compatible — compiles to both wasm32-wasip1 and native targets. Uses Spin SDK on WASM, Axum on native.

Crate: a2a_http_server · Path: crates/a2a_http_server
Description (Cargo.toml): A2A HTTP server - WASM default, native testing support

Role

Target-adaptive A2A HTTP server: uses Spin SDK on WASM and Axum on native, with identical APIs. Handles JSON-RPC dispatch for all A2A v1.0 methods, SSE streaming, and agent card serving. Protocol instance injection with no global state.

Feature flags

From crates/a2a_http_server/Cargo.toml:

Feature	Purpose
default	Enables core
core	Core A2A functionality (standard methods); enables a2a_protocol_core/core
observability	Emit OTEL spans/metrics + W3C trace propagation
schema	JSON schema generation via schemars; enables a2a_protocol_core/spec-compliant
discovery	Extended agent discovery; enables a2a_protocol_core/extended-discovery
event-stream	SSE streaming support; enables a2a_protocol_core/event-stream
streaming	Alias for event-stream
files	File handling; enables a2a_protocol_core/file-handling
push	Push notifications; enables a2a_protocol_core/push-notifications
all	Enables schema, discovery, event-stream, files, push, observability

Public API (from src/lib.rs)

Module method — A2A v1.0 JSON-RPC method name constants:

• PING, SEND_MESSAGE, SEND_STREAMING_MESSAGE, GET_AGENT_CARD, GET_EXTENDED_AGENT_CARD, GET_TASK, CANCEL_TASK, LIST_TASKS

Core types:

• A2AHttpServer — the server instance (target-adaptive: Spin SDK or Axum)
  • A2AHttpServer::new_with_a2a_methods(agent_card) — create with standard A2A routes
  • server.agent_id() — get agent identifier
  • server.can_serve() — check readiness (native)
• A2AAppPort trait — application port for delegating methods to SDK layer (re-exported from a2a_app_ports)
• A2AStreamingAppPort trait — streaming variant (native + event-stream feature)
• init_logging(component_name) — convenience logging initializer
• log_server_info(agent_id) — log server creation with target info

Re-exports:

• From a2a_protocol_core: A2AProtocol, AgentCard, A2A_PROTOCOL_VERSION
• From protocol_transport_core: JsonRpcIncoming, JsonRpcResponse, JSONRPC_VERSION

Example sketch

use a2a_http_server::{A2AHttpServer, AgentCard, init_logging};

init_logging("my-agent");

let card = AgentCard::new("my-agent".to_string());
let server = A2AHttpServer::new_with_a2a_methods(card);

// On WASM: pass Spin HTTP request to server
// On native: server exposes an Axum router

Full API reference: cargo doc -p a2a_http_server --no-deps --all-features