Push Notifications

A long-running task does not require you to hold a connection open. Register a webhook against the task and the agent gateway will POST task updates to it as the task progresses. The agent card advertises this on its capabilities object:

{ "capabilities": { "streaming": true, "pushNotifications": true } }

Push notifications complement streaming rather than replacing it. Streaming is for a caller waiting on the result now; push is for a caller that wants to hang up and be told later.

Registering a target

Four methods manage push configs on a task. All are POST to the gateway root, with the method name in the JSON-RPC envelope.

Method	Purpose
`CreateTaskPushNotificationConfig`	Register a webhook against a task
`GetTaskPushNotificationConfig`	Read one config back
`ListTaskPushNotificationConfigs`	List every config on a task
`DeleteTaskPushNotificationConfig`	Remove one

curl -X POST https://agent-my-agent.noorle.com/ \
  -H "Authorization: Bearer eyJhbGc..." \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "CreateTaskPushNotificationConfig",
    "params": {
      "taskId": "0198f2c1-...",
      "url": "https://hooks.example.com/noorle/task-updates",
      "token": "a-verifier-you-generate",
      "authentication": {
        "scheme": "bearer",
        "credentials": "YOUR_WEBHOOK_CREDENTIAL"
      }
    }
  }'

Field	Required	Description
`taskId`	Yes	The task to watch
`url`	Yes	Where to `POST` the callback
`id`	No	Config identifier. Omit it and the server mints one
`token`	No	An opaque value echoed back on every callback so you can verify it came from Noorle
`authentication`	No	Credential the gateway attaches when calling your endpoint

authentication.scheme accepts bearer or basic. Any other scheme is refused rather than guessed at, so a credential is never sent under a scheme the gateway did not recognize.

URL rules

The callback URL is validated before anything is sent to it:

HTTPS only.
No credentials in the URL — no user:password@ userinfo section.
Public hosts only. Private-range and cloud metadata addresses are refused.

What arrives at your endpoint

The gateway sends a POST whose body is the full task snapshot, wrapped as an A2A stream response:

{
  "task": {
    "id": "0198f2c1-...",
    "contextId": "0198f2b0-...",
    "status": { "state": "TASK_STATE_COMPLETED" },
    "artifacts": [ /* ... */ ]
  }
}

This is byte-for-byte the shape GetTask returns for the same task, so an A2A SDK deserializes a callback body with the same type it uses for a task read. Your handler does not need a separate parser. Two headers matter:

Header	When	Value
`A2A-Notification-Token`	If you set `token`	The exact value you registered
`Authorization`	If you set `authentication`	`Bearer <credentials>` or `Basic <credentials>`

Verify the token before acting on a callback. Because the body is a full snapshot rather than a delta, a handler that processes callbacks out of order still converges — take the latest snapshot and discard the older one.

Delivery contract

Not every update is equally durable, and the difference is deliberate. Notifications are sorted into two lanes by the task state they carry.

Lane	States	Guarantee
Reserved	`TASK_STATE_COMPLETED`, `TASK_STATE_FAILED`, `TASK_STATE_CANCELED`, `TASK_STATE_REJECTED`, `TASK_STATE_INPUT_REQUIRED`, `TASK_STATE_AUTH_REQUIRED`	Never dropped to make room for other traffic. Gets its own capacity and one retry on failure
Best effort	Intermediate `TASK_STATE_WORKING` and artifact-only progress updates	May be dropped under load. No retry

The reasoning is that the notifications you build on are “the task finished” and “the task needs something from you.” Those get a lane that heavy progress traffic cannot starve. Progress chatter is useful when it arrives and safe to lose when the system is busy.

Do not build a progress bar that assumes every working update arrives. Treat intermediate updates as hints. If you need every intermediate step, use SendStreamingMessage or SubscribeToTask, which stream the full event sequence.

Delivery is best-effort overall, not transactional: a callback endpoint that is down for the duration of a task’s final notification will miss it even in the reserved lane. For work where missing a completion is unacceptable, treat push as the fast path and reconcile with GetTask on a slower timer.

Choosing between push and streaming

You want	Use
The result now, connection held open	`SendStreamingMessage`
Every intermediate event, reliably	`SendStreamingMessage` or `SubscribeToTask`
To disconnect and be called back when it matters	Push notifications
To reattach to a task you already started	`SubscribeToTask`

Tasks — GetTask, CancelTask, SubscribeToTask
SendStreamingMessage
A2A Protocol

Overview

REST API

MCP Protocol

A2A Protocol

Noorle CLI

Push Notifications

Registering a target

URL rules

What arrives at your endpoint

Delivery contract

Choosing between push and streaming

​Registering a target

​URL rules

​What arrives at your endpoint

​Delivery contract

​Choosing between push and streaming

​Related

Registering a target

URL rules

What arrives at your endpoint

Delivery contract

Choosing between push and streaming

Related