First draft of Event Mesh definition (#5454)

* First draft of Event Mesh definition

Signed-off-by: Matthias Wessendorf <mwessend@redhat.com>

* Adding some clarification on the 'event broker' term, hopefully

Signed-off-by: Matthias Wessendorf <mwessend@redhat.com>

* formatting

Signed-off-by: Matthias Wessendorf <mwessend@redhat.com>

* Adding the Event Mesh to the Eventing nav bar, for now...

Signed-off-by: Matthias Wessendorf <mwessend@redhat.com>

---------

Signed-off-by: Matthias Wessendorf <mwessend@redhat.com>

config/nav.yml

@@ -177,6 +177,7 @@ nav:
 ###############################################################################
     - Eventing:
       - Knative Eventing overview: eventing/README.md
+      - Event Mesh: eventing/event-mesh.md
       - Resources:
         - Brokers:
           - About Brokers: eventing/brokers/README.md

docs/eventing/event-mesh.md

@@ -0,0 +1,17 @@
+# Event Mesh
+
+An Event Mesh is a dynamic infrastructure that is designed to smoothly transport events from producers to consumers via a network of interconnected _event brokers_ across any environment, and even between clouds in a seamless and loosely coupled way. In an Event Mesh both, producing and consuming application, can leverage their platform native event APIs. For instance a Phyton or Golang application can produce an event, using their native APIs, while a consuming application written in Java or Node.js can subscribe to it with their own native APIs as well.
+
+## Knative Event Mesh
+
+The above mentioned _event brokers_ are directly mapping to a key API in Knative Eventing: The `Broker` API offers a discoverable endpoint for event ingress and the `Trigger` API completes the offering with its event delivery capabilities. With these APIs Knative Eventing offers an Event Mesh as defined above:
+
+![Raw Trace](images/mesh.png)
+
+As visible in the above diagram, the Event Mesh is defined with the `Broker` and `Trigger` APIs for the ingress and the egress of events. Knative Eventing complements the Event Mesh with its Duck type APIs, offering a pool of connector for sending events to the `Broker` and routing events to subscribers using the `Trigger`:
+
+* **Events Ingress**: Support for a connectors API: Source duck type & Callable/Addressable Duck type. Even without any sources installed.
+* **Event routing**: Broker + Triggers
+* **Event egress** : Sinks API (i.e Callable)
+
+It is important to note that `Source` and `Sink` are not directly part of the Event Mesh. However they are complementary, and benefit from the good Ducktype APIs (`Callable`/`Addressable`) for a smooth integration or connection with the "Event Mesh".