Support signature type cloudevent

This signature type should support HTTP requests with CloudEvent objects delivered via either structured and binary CloudEvent objects. Usually a CloudEvents SDK can handle transforming the HTTP request to a language-native CloudEvent object.

New signature cloudevent in Functions Framework contract

The end-user should see the parameter cloudevent, which is a native CloudEvent object using the CloudEvent SDK if possible.

Example User Experience (in Node)

function handler(cloudevent) {
  console.log(cloudevent.id);
  console.log(cloudevent.data.message);
  console.log(cloudevent.custom_values_should_be_accepted);
  return "anything"
}

Example HTTP requests

The CloudEvents specification requires support for both "binary" and "structured" encodings for CloudEvents delivered via HTTP. The Function Framework must support both encodings. A CloudEvents SDK might make this easier, but most SDKs are not complete, so logic may exist within the Framework.

Examples:

Binary content mode

POST /any/url/is/accepted HTTP/1.1
Host: example.com
ce-specversion: 1.0
ce-type: com.example.someevent
ce-time: 2018-04-05T03:56:24Z
ce-id: 1234-1234-1234
ce-source: /mycontext/subcontext
x-google-custom-header: 77
Content-Type: <contentType>
Content-Length: 33
{
    "message": "Hello World!"
}

Structured content mode

POST /someresource HTTP/1.1
Host: example.com
Content-Type: <contentType>
Content-Length: 266
{
    "specversion": "1.0",
    "type": "com.example.someevent",
    "time": "2018-04-05T03:56:24Z",
    "id": "1234-1234-1234",
    "source": "/mycontext/subcontext",
    "datacontenttype": "application/json",
    "data": {
        "message": "Hello World!"
    },
    "custom_values_should_be_accepted": 42
}

A user should be able to access all of the HTTP headers.
A user should be able to access the body of the CloudEvent in the data field of an object.

• Example PRs:
  • Node
  • Go
  • .NET