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Version: 8.9 (unreleased)

A2A Client Webhook connector

The A2A Client Webhook connector receives callbacks from remote A2A agents via HTTP webhooks.

It is typically paired with the A2A Client connector when using the Notification response retrieval method. This connector is based on the HTTP Webhook connector and shares most of its configuration options.

Create an A2A Client Webhook connector task​

  1. Start building your BPMN diagram. You can use the A2A Client Webhook connector with an Intermediate Catch Event or with a Receive Task.
  2. Select the applicable element and change its template to a A2A Client Webhook connector.
  3. Fill in all required properties.
  4. Complete your BPMN diagram.
  5. Deploy the diagram to activate the A2A Client Webhook connector.
  6. Navigate to the Webhooks tab in the properties panel to see the webhook URL.
warning

Use the URL from step 6 in the A2A Client connector configuration, then redeploy your BPMN diagram. There’s currently no automatic way to inject the webhook URL into the A2A Client connector configuration.

note

In Camunda 8 Self-Managed, you must construct the webhook URL manually. See HTTP webhook connector documentation for more information.

Make the A2A Client Webhook connector executable​

To make the A2A Client Webhook connector executable, fill out the mandatory fields highlighted in red in the properties panel on the right.

Configure the following:

  • Webhook ID (required): Unique identifier for the webhook endpoint. This ID becomes part of the webhook URL.
  • A2A Client Response (required): FEEL expression referencing the response from the A2A Client connector.
note

For authentication and authorization, see HTTP Webhook connector documentation for more information.

  • Activation condition: FEEL expression to determine if the payload meets the criteria to activate the intermediate catch event. In most cases, the default value is sufficient; it checks whether the received task is in a final state.
  • Message ID expression (optional): Extract the message ID from the incoming request. The message ID uniquely identifies the message, is evaluated in the connector runtime, and the result is used to correlate the message. In most cases you don’t need to configure this, but it’s useful for deduplication or specific correlation behavior. See Message correlation for more details.
  • Message TTL (optional): Sets the time-to-live (TTL) for correlated messages. TTL defines the time a message is buffered in Zeebe before correlation (if it can't be correlated immediately). The value is specified as an ISO-8601 duration. For example, PT1H sets the TTL to one hour. See Message buffering for more details.
note

Correlation key (process) and Correlation key (payload) are prefilled with the required values and hidden; there’s no need to modify them.

  • Result variable (optional): Typically leave empty.
  • Result expression: FEEL expression to extract the result from the payload. Typically, extract the request.body field using a FEEL expression such as = {a2aAgentResponse: request.body} or = {toolCallResult: request.body}.
tip

As in the HTTP Webhook connector, the payload is accessible via the request variable. Use the following references to access data:

  • Body: request.body..
  • Headers: request.headers..
  • URL parameters: request.params..