Struct A2aClient 

pub struct A2aClient { /* private fields */ }

A client for communicating with A2A-compliant agents.

All A2A protocol methods are available as async methods. Create a client via ClientBuilder or the A2aClient::from_card shorthand.

Example

use a2a_protocol_client::ClientBuilder;

let client = ClientBuilder::new("http://localhost:8080").build()?;

Implementations

impl A2aClient

pub fn from_card(card: &AgentCard) -> ClientResult<Self>

Creates a client from an AgentCard using the recommended defaults.

Selects the transport based on the agent’s preferred protocol.

Errors

Returns crate::error::ClientError::InvalidEndpoint if the agent card URL is malformed or the transport cannot be constructed.

pub const fn config(&self) -> &ClientConfig

Returns a reference to the active client configuration.

impl A2aClient

pub async fn get_extended_agent_card( &self, ) -> ClientResult<AuthenticatedExtendedCardResponse>

Fetches the full (private) agent card, authenticating the request.

Calls GetExtendedAgentCard. The returned card may include private skills, security schemes, or additional interfaces not exposed in the public /.well-known/agent.json.

The caller must have registered auth credentials via crate::auth::AuthInterceptor or equivalent before calling this method.

Errors

Returns ClientError on transport or protocol errors.

impl A2aClient

pub async fn set_push_config( &self, config: TaskPushNotificationConfig, ) -> ClientResult<TaskPushNotificationConfig>

Registers or replaces a push notification configuration for a task.

Calls CreateTaskPushNotificationConfig. Returns the configuration as stored by the server (including the server-assigned id).

Errors

Returns ClientError::Protocol with a2a_protocol_types::ErrorCode::PushNotificationNotSupported if the agent does not support push notifications.

pub async fn get_push_config( &self, task_id: impl Into<String>, id: impl Into<String>, ) -> ClientResult<TaskPushNotificationConfig>

Retrieves a push notification configuration by task ID and config ID.

Calls GetTaskPushNotificationConfig.

Errors

Returns ClientError on transport or protocol errors.

pub async fn list_push_configs( &self, params: ListPushConfigsParams, ) -> ClientResult<ListPushConfigsResponse>

Lists push notification configurations for a task with pagination.

Calls ListTaskPushNotificationConfigs.

Errors

Returns ClientError on transport or protocol errors.

pub async fn delete_push_config( &self, task_id: impl Into<String>, id: impl Into<String>, ) -> ClientResult<()>

Deletes a push notification configuration.

Calls DeleteTaskPushNotificationConfig.

Errors

Returns ClientError on transport or protocol errors.

impl A2aClient

pub async fn send_message( &self, params: MessageSendParams, ) -> ClientResult<SendMessageResponse>

Sends a message to the agent and waits for a complete response.

Calls the SendMessage JSON-RPC method. The agent may respond with either a completed Task or an immediate Message.

Client-level configuration (e.g. return_immediately, history_length) is automatically merged into the request parameters. Per-request values take precedence.

Errors

Returns ClientError on transport, serialization, or protocol errors.

pub async fn stream_message( &self, params: MessageSendParams, ) -> ClientResult<EventStream>

Sends a message and returns a streaming EventStream of progress events.

Calls the SendStreamingMessage JSON-RPC method. The agent responds with an SSE stream of a2a_protocol_types::StreamResponse events.

Errors

Returns ClientError on transport or protocol errors.

impl A2aClient

pub async fn get_task(&self, params: TaskQueryParams) -> ClientResult<Task>

Retrieves a task by ID.

Calls the GetTask JSON-RPC method.

Errors

Returns ClientError::Protocol with a2a_protocol_types::ErrorCode::TaskNotFound if no task with the given ID exists.

pub async fn list_tasks( &self, params: ListTasksParams, ) -> ClientResult<TaskListResponse>

Lists tasks visible to the caller.

Calls the ListTasks JSON-RPC method. Results are paginated; use params.page_token to fetch subsequent pages.

Errors

Returns ClientError on transport or protocol errors.

pub async fn cancel_task(&self, id: impl Into<String>) -> ClientResult<Task>

Requests cancellation of a running task.

Calls the CancelTask JSON-RPC method. Returns the task in its post-cancellation state.

Errors

Returns ClientError::Protocol with a2a_protocol_types::ErrorCode::TaskNotCancelable if the task cannot be canceled in its current state.

pub async fn subscribe_to_task( &self, id: impl Into<String>, ) -> ClientResult<EventStream>

Subscribes to the SSE stream for an in-progress task.

Calls the SubscribeToTask method. Useful after an unexpected disconnection from a SendStreamingMessage call.

Events already delivered before the reconnect are not replayed.

Errors

Returns ClientError::Protocol with a2a_protocol_types::ErrorCode::TaskNotFound if the task is not in a streaming-eligible state.

Trait Implementations

impl Debug for A2aClient

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.