howtooutputbinding (#36)

howto/send-events-with-output-bindings/Readme.md

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+# Send events to external systems using Output Bindings
+
+Using bindings, its possible to invoke external resources without tying in to special SDK or libraries.
+For a compelete sample showing output bindings, visit this [link](<PLACEHOLDER>).
+
+## 1. Create a binding
+
+An output binding represents a resource that Dapr will use invoke and send messages to.
+
+For the purpose of this guide, we'll use a Kafka binding. You can find a list of the different binding specs [here](../concepts/bindings//specs).
+
+Create the following YAML file, named binding.yaml, and save this to the /components sub-folder in your application directory.
+
+*Note: When running in Kubernetes, apply this file to your cluster using `kubectl apply -f binding.yaml`*
+
+```
+apiVersion: actions.io/v1alpha1
+kind: Component
+metadata:
+  name: myEvent
+spec:
+  type: bindings.kafka
+  metadata:
+  - name: brokers
+    value: localhost:9092
+  - name: publishTopic
+    value: topic1
+```
+
+Here, we create a new binding component with the name of `myEvent`.<br>
+Inside the `metadata` section, we configure Kafka related properties such as the topic to publish the message to and the broker.
+
+## 2. Send an event
+
+All that's left now is to invoke the bindings endpoint on a running Dapr instance.
+
+We can do so using HTTP:
+
+```
+curl -X POST -H  http://localhost:3500/v1.0/bindings/myEvent -d '{ data: { "message": "Hi!" } }'
+```
+
+As seen above, we invoked the `/binding` endpoint with the name of the binding to invoke, in our case its `myEvent`.<br>
+The payload goes inside the `data` field.