Add Azure SignalR documentation (#270)

Co-authored-by: Yaron Schneider <yaronsc@microsoft.com>

concepts/bindings/README.md

@@ -18,22 +18,23 @@ Every binding has its own unique set of properties. Click the name link to see t
 
 | Name  | Input Binding | Output Binding | Status
 | ------------- | -------------- | -------------  | ------------- |
-| [Kafka](./specs/kafka.md) | ✅ | ✅ | Experimental |
-| [RabbitMQ](./specs/rabbitmq.md) | ✅  | ✅ | Experimental |
-| [AWS SQS](./specs/sqs.md) | ✅ | ✅ | Experimental |
-| [AWS SNS](./specs/sns.md) |  | ✅ | Experimental |
-| [Azure EventHubs](./specs/eventhubs.md) | ✅ | ✅ | Experimental |
-| [Azure CosmosDB](./specs/cosmosdb.md) | | ✅ | Experimental |
-| [GCP Storage Bucket](./specs/gcpbucket.md)  | | ✅ | Experimental |
-| [HTTP](./specs/http.md) |  | ✅ | Experimental |
-| [MQTT](./specs/mqtt.md) | ✅ | ✅ | Experimental |
-| [Redis](./specs/redis.md) |  | ✅ | Experimental |
-| [AWS DynamoDB](./specs/dynamodb.md) | | ✅ | Experimental |
-| [AWS S3](./specs/s3.md) | | ✅ | Experimental |
-| [Azure Blob Storage](./specs/blobstorage.md) | | ✅ | Experimental |
-| [Azure Service Bus Queues](./specs/servicebusqueues.md) | ✅ | ✅ | Experimental |
-| [GCP Cloud Pub/Sub](./specs/gcppubsub.md) | ✅ | ✅ | Experimental |
-| [Kubernetes Events](./specs/kubernetes.md) | ✅ |  | Experimental |
+| [Kafka](./specs/kafka.md) | V | V | Experimental |
+| [RabbitMQ](./specs/rabbitmq.md) | V  | V | Experimental |
+| [AWS SQS](./specs/sqs.md) | V | V | Experimental |
+| [AWS SNS](./specs/sns.md) |  | V | Experimental |
+| [Azure EventHubs](./specs/eventhubs.md) | V | V | Experimental |
+| [Azure CosmosDB](./specs/cosmosdb.md) | | V | Experimental |
+| [Azure SignalR](./specs/signalr.md) | | V | Experimental |
+| [GCP Storage Bucket](./specs/gcpbucket.md)  | | V | Experimental |
+| [HTTP](./specs/http.md) |  | V | Experimental |
+| [MQTT](./specs/mqtt.md) | V | V | Experimental |
+| [Redis](./specs/redis.md) |  | V | Experimental |
+| [AWS DynamoDB](./specs/dynamodb.md) | | V | Experimental |
+| [AWS S3](./specs/s3.md) | | V | Experimental |
+| [Azure Blob Storage](./specs/blobstorage.md) | | V | Experimental |
+| [Azure Service Bus Queues](./specs/servicebusqueues.md) | V | V | Experimental |
+| [GCP Cloud Pub/Sub](./specs/gcppubsub.md) | V | V | Experimental |
+| [Kubernetes Events](./specs/kubernetes.md) | V |  | Experimental |
 
 ## Input Bindings
 

concepts/bindings/specs/signalr.md

@@ -0,0 +1,46 @@
+# Azure SignalR Binding Spec
+
+```yaml
+apiVersion: dapr.io/v1alpha1
+kind: Component
+metadata:
+  name: <name>
+spec:
+  type: bindings.azure.signalr
+  metadata:
+  - name: connectionString
+    value: Endpoint=https://<your-azure-signalr>.service.signalr.net;AccessKey=<your-access-key>;Version=1.0;
+  - name: hub  # Optional
+    value: <hub name>
+```
+
+The metadata `connectionString` contains the Azure SignalR connection string.
+The optional `hub` metadata value defines the hub in which the message will be send. The hub can be dynamically defined as a metadata value when publishing to an output binding (key is "hub").
+
+## Additional information
+
+By default the Azure SignalR output binding will broadcast messages to all connected users. To narrow the audience there are two options, both configurable in the Metadata property of the message:
+
+- group: will send the message to a specific Azure SignalR group
+- user: will send the message to a specific Azure SignalR user
+
+Applications publishing to an Azure SignalR output binding should send a message with the following contract:
+
+```json
+{
+    "data": {
+        "Target": "<enter message name>",
+        "Arguments": [
+            {
+                "sender": "dapr",
+                "text": "Message from dapr output binding"
+            }
+        ]
+    },
+    "metadata": {
+        "group": "chat123"
+    }
+}
+```
+
+For more information on integration Azure SignalR into a solution check the [documentation](https://docs.microsoft.com/en-us/azure/azure-signalr/)