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A2A Client Sample

This sample project is a small ASP.NET Core Razor Pages app that connects to the A2A host served by CrestApps.OrchardCore.Cms.Web when running with Aspire. It provides a simple UI to explore A2A capabilities:

  • Home – Prerequisites and setup instructions.
  • Agents – List all available agents from the A2A host and send messages to them.

Run with Aspire​

The easiest way to run this sample is using the Aspire AppHost project:

  1. Make sure Docker Desktop is installed and running locally.
  2. Set CrestApps.Aspire.AppHost as your startup project.
  3. Run the project. The Aspire dashboard will open in your browser.
  4. From the Aspire dashboard, click on the endpoint for the resource you want to access:
    • orchardcore — Opens the Orchard Core CMS application (on port 5001).
    • a2aclientsample — Opens the A2A Client sample UI (on port 5003).
note

The Aspire AppHost orchestrates several services including Ollama (AI model host), Elasticsearch, Redis, and both the Orchard Core app and the sample clients. All service dependencies and environment variables are configured automatically.

A2A Host Feature Requirement​

If the A2A Host feature is not enabled, requests to /.well-known/agent-card.json will return 404. Enable the A2A Host feature in the default tenant:

  • Feature ID: CrestApps.OrchardCore.AI.A2A.Host
  • Admin UI: Tools → Features

After enabling the feature, refresh the sample UI to see available agents.

Configuration​

The A2A endpoint is configured via A2A:Endpoint. Aspire sets it automatically, but you can override it in appsettings.json:

{
  "A2A": {
    "Endpoint": "https://localhost:5001"
  }
}

The agent card is automatically discovered at /.well-known/agent-card.json relative to the endpoint.