Struct A2AClient 

pub struct A2AClient { /* private fields */ }

A2A client for communicating with remote agents

Implementations

impl A2AClient

pub async fn from_card_url(base_url: impl AsRef<str>) -> A2AResult<Self>

Create a new A2A client from an agent card URL

This will fetch the agent card from the specified URL and use the advertised v1 endpoints from the card for all subsequent requests.

Uses a default reqwest::Client for HTTP requests. For custom HTTP configuration, use from_card_url_with_client().

Example

use a2a_client::A2AClient;

let client = A2AClient::from_card_url("https://agent.example.com").await?;

Errors

Returns an error if the agent card cannot be fetched, parsed, or does not advertise a supported JSONRPC or HTTP+JSON interface.

pub async fn from_card_url_with_client( base_url: impl AsRef<str>, http_client: Client, ) -> A2AResult<Self>

Create a new A2A client from an agent card URL with a custom HTTP client

This allows you to provide a pre-configured reqwest::Client with custom settings like timeouts, proxies, TLS config, default headers, etc.

Example

use a2a_client::A2AClient;
use reqwest::Client;
use std::time::Duration;

let http_client = Client::builder()
    .timeout(Duration::from_secs(30))
    .build()?;

let client = A2AClient::from_card_url_with_client(
    "https://agent.example.com",
    http_client
).await?;

Errors

Returns an error if the agent card cannot be fetched, the response status is not successful, JSON parsing fails, or the card does not advertise a supported interface.

pub fn from_card(agent_card: AgentCard) -> A2AResult<Self>

Create a new A2A client directly from an agent card

This is useful when you already have an agent card and don’t need to fetch it. Uses a default reqwest::Client. For custom HTTP configuration, use from_card_with_client().

Example

use a2a_client::A2AClient;
use a2a_types::AgentCard;

let client = A2AClient::from_card(agent_card)?;

Errors

Returns an error if the agent card does not advertise a supported JSONRPC or HTTP+JSON interface.

pub fn from_card_with_client( agent_card: AgentCard, http_client: Client, ) -> A2AResult<Self>

Create a new A2A client from an agent card with a custom HTTP client

This allows you to provide a pre-configured reqwest::Client with custom settings like timeouts, proxies, TLS config, default headers, etc.

Example

use a2a_client::A2AClient;
use a2a_types::AgentCard;
use reqwest::Client;
use std::time::Duration;

let http_client = Client::builder()
    .timeout(Duration::from_secs(30))
    .default_headers({
        let mut headers = reqwest::header::HeaderMap::new();
        headers.insert("X-Custom-Header", "value".parse()?);
        headers
    })
    .build()?;

let client = A2AClient::from_card_with_client(agent_card, http_client)?;

Errors

Returns an error if the agent card does not advertise a supported JSONRPC or HTTP+JSON interface.

pub fn from_card_with_headers( agent_card: AgentCard, headers: HashMap<String, String>, ) -> A2AResult<Self>

Create a new A2A client from an agent card with custom headers

This is a convenience method that builds a reqwest::Client with the provided headers and uses it to create the A2AClient.

Example

use a2a_client::A2AClient;
use a2a_types::AgentCard;
use std::collections::HashMap;

let mut headers = HashMap::new();
headers.insert("Authorization".to_string(), "Bearer token123".to_string());
headers.insert("X-API-Key".to_string(), "my-api-key".to_string());

let client = A2AClient::from_card_with_headers(agent_card, headers)?;

Errors

Returns an error if the agent card is invalid, headers cannot be parsed, or the HTTP client cannot be built.

pub fn with_auth_token(self, token: impl Into<String>) -> Self

Set authentication token (builder pattern)

pub fn agent_card(&self) -> &AgentCard

Get the cached agent card

pub async fn fetch_agent_card( &self, base_url: impl AsRef<str>, ) -> A2AResult<AgentCard>

Fetch a fresh agent card from the base URL

Errors

Returns an error if the network request fails, the response status is not successful, or JSON parsing fails.

pub async fn fetch_extended_agent_card_if_available( &self, ) -> A2AResult<Option<AgentCard>>

Fetch the extended agent card if the agent advertises one.

Checks capabilities.extended_agent_card on the cached public card first. If the agent does not advertise an extended card, returns None immediately without making a network request.

Errors

Returns an error if the network request fails or the response cannot be parsed.

pub async fn send_message( &self, request: SendMessageRequest, ) -> A2AResult<SendMessageResponse>

Send a message using the A2A v1 surface.

pub async fn send_streaming_message( &self, request: SendMessageRequest, ) -> A2AResult<Pin<Box<dyn Stream<Item = A2AResult<StreamResponse>> + Send>>>

Send a streaming message using the A2A v1 surface.

pub async fn get_task(&self, request: GetTaskRequest) -> A2AResult<Task>

Retrieve a task using the A2A v1 surface.

pub async fn list_tasks( &self, request: ListTasksRequest, ) -> A2AResult<ListTasksResponse>

List tasks using the A2A v1 surface.

pub async fn cancel_task(&self, request: CancelTaskRequest) -> A2AResult<Task>

Cancel a task using the A2A v1 surface.

pub async fn subscribe_to_task( &self, request: SubscribeToTaskRequest, ) -> A2AResult<Pin<Box<dyn Stream<Item = A2AResult<StreamResponse>> + Send>>>

Subscribe to a task stream using the A2A v1 surface.

pub async fn get_extended_agent_card( &self, request: GetExtendedAgentCardRequest, ) -> A2AResult<AgentCard>

Fetch the extended agent card using the A2A v1 surface.

pub async fn create_task_push_notification_config( &self, request: TaskPushNotificationConfig, ) -> A2AResult<TaskPushNotificationConfig>

Create or replace a task push notification config using the A2A v1 surface.

pub async fn get_task_push_notification_config( &self, request: GetTaskPushNotificationConfigRequest, ) -> A2AResult<TaskPushNotificationConfig>

Fetch a task push notification config using the A2A v1 surface.

pub async fn list_task_push_notification_configs( &self, request: ListTaskPushNotificationConfigsRequest, ) -> A2AResult<ListTaskPushNotificationConfigsResponse>

List task push notification configs using the A2A v1 surface.

pub async fn delete_task_push_notification_config( &self, request: DeleteTaskPushNotificationConfigRequest, ) -> A2AResult<()>

Delete a task push notification config using the A2A v1 surface.

pub async fn call_extension_method<TParams, TResponse>( &self, method: &str, params: TParams, ) -> A2AResult<TResponse>

where TParams: Serialize, TResponse: for<'de> Deserialize<'de>,

Call a custom extension method

This allows calling custom JSON-RPC methods defined by agent extensions.

Errors

Returns an error if the RPC request fails or the remote agent returns an error response.

Trait Implementations

impl Clone for A2AClient

fn clone(&self) -> A2AClient

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.