Task Management

Beyond sending messages, the client provides methods for querying, listing, and canceling tasks.

Get a Task

Retrieve a task by ID:

#![allow(unused)]
fn main() {
use a2a_protocol_sdk::types::params::TaskQueryParams;

let task = client.get_task(TaskQueryParams {
    tenant: None,
    id: "task-abc".into(),
    history_length: Some(10),  // Include last 10 messages
}).await?;

println!("Task: {} ({:?})", task.id, task.status.state);

if let Some(artifacts) = &task.artifacts {
    println!("Artifacts: {}", artifacts.len());
}

if let Some(history) = &task.history {
    println!("Messages: {}", history.len());
}
}

List Tasks

Query tasks with filtering and pagination:

#![allow(unused)]
fn main() {
use a2a_protocol_sdk::types::params::ListTasksParams;

let response = client.list_tasks(ListTasksParams {
    tenant: None,
    context_id: Some("ctx-123".into()),       // Filter by context
    status: Some(TaskState::Completed),         // Filter by state
    page_size: Some(20),                        // 20 per page
    page_token: None,                           // First page
    status_timestamp_after: None,
    include_artifacts: Some(true),
    history_length: None,
}).await?;

for task in &response.tasks {
    println!("{}: {:?}", task.id, task.status.state);
}

// Paginate
if let Some(token) = &response.next_page_token {
    let next_page = client.list_tasks(ListTasksParams {
        page_token: Some(token.clone()),
        ..Default::default()
    }).await?;
}
}

Filtering Options

Cancel a Task

Request cancellation of a running task:

#![allow(unused)]
fn main() {
let task = client.cancel_task("task-abc").await?;

println!("Task state: {:?}", task.status.state);
// → Canceled (if the agent supports cancellation)
}

Cancellation is cooperative — the agent's executor must implement the cancel method. If the agent doesn't support cancellation, you'll get an error response.

Cancellation States

Next Steps

• Error Handling — Handling API errors
• Streaming Responses — Real-time event streams