Add priority for rabbitmq (#3282)

* add priority for rabbitmq

Signed-off-by: yaron2 <schneider.yaron@live.com>

* update subscription version

Signed-off-by: yaron2 <schneider.yaron@live.com>

---------

Signed-off-by: yaron2 <schneider.yaron@live.com>

daprdocs/content/en/reference/components-reference/supported-pubsub/setup-rabbitmq.md

@@ -183,14 +183,15 @@ Setting `exchangeKind` to `"topic"` uses the topic exchanges, which are commonly
 Messages with a `routing key` will be routed to one or many queues based on the `routing key` defined in the metadata when subscribing.
 The routing key is defined by the `routingKey` metadata. For example, if an app is configured with a routing key `keyA`:
 
-```
-apiVersion: dapr.io/v1alpha1
+```yaml
+apiVersion: dapr.io/v2alpha1
 kind: Subscription
 metadata:
-  name: order_pub_sub
+  name: orderspubsub
 spec:
   topic: B
-  route: /B
+  routes: 
+    default: /B
   pubsubname: pubsub
   metadata:
     routingKey: keyA
@@ -210,14 +211,15 @@ client.PublishEvent(context.Background(), "pubsub", "B", []byte("this is another
 Multiple routing keys can be separated by commas.  
 The example below binds three `routingKey`: `keyA`, `keyB`, and `""`. Note the binding method of empty keys.
 
-```
-apiVersion: dapr.io/v1alpha1
+```yaml
+apiVersion: dapr.io/v2alpha1
 kind: Subscription
 metadata:
-  name: order_pub_sub
+  name: orderspubsub
 spec:
   topic: B
-  route: /B
+  routes: 
+    default: /B
   pubsubname: pubsub
   metadata:
     routingKey: keyA,keyB,
@@ -226,6 +228,168 @@ spec:
 
 For more information see [rabbitmq exchanges](https://www.rabbitmq.com/tutorials/amqp-concepts.html#exchanges).
 
+## Use priority queues
+
+Dapr supports RabbitMQ [priority queues](https://www.rabbitmq.com/priority.html). To set a priority for a queue, use the `maxPriority` topic subscription metadata.
+
+### Declarative priority queue example
+
+```yaml
+apiVersion: dapr.io/v2alpha1
+kind: Subscription
+metadata:
+  name: pubsub
+spec:
+  topic: checkout
+  routes: 
+    default: /orders
+  pubsubname: order-pub-sub
+  metadata:
+    maxPriority: 3
+```
+
+### Programmatic priority queue example
+
+{{< tabs Python JavaScript Go>}}
+
+{{% codetab %}}
+
+```python
+@app.route('/dapr/subscribe', methods=['GET'])
+def subscribe():
+    subscriptions = [
+      {
+        'pubsubname': 'pubsub',
+        'topic': 'checkout',
+        'routes': {
+          'default': '/orders'
+        },
+        'metadata': {'maxPriority': '3'}
+      }
+    ]
+    return jsonify(subscriptions)
+```
+
+{{% /codetab %}}
+
+{{% codetab %}}
+
+```javascript
+const express = require('express')
+const bodyParser = require('body-parser')
+const app = express()
+app.use(bodyParser.json({ type: 'application/*+json' }));
+
+const port = 3000
+
+app.get('/dapr/subscribe', (req, res) => {
+  res.json([
+    {
+      pubsubname: "pubsub",
+      topic: "checkout",
+      routes: {
+        default: '/orders'
+      },
+      metadata: {
+        maxPriority: '3'
+      }
+    }
+  ]);
+})
+```
+
+{{% /codetab %}}
+
+{{% codetab %}}
+
+```go
+package main
+
+	"encoding/json"
+	"net/http"
+
+const appPort = 3000
+
+type subscription struct {
+	PubsubName string            `json:"pubsubname"`
+	Topic      string            `json:"topic"`
+	Metadata   map[string]string `json:"metadata,omitempty"`
+	Routes     routes            `json:"routes"`
+}
+
+type routes struct {
+	Rules   []rule `json:"rules,omitempty"`
+	Default string `json:"default,omitempty"`
+}
+
+// This handles /dapr/subscribe
+func configureSubscribeHandler(w http.ResponseWriter, _ *http.Request) {
+	t := []subscription{
+		{
+			PubsubName: "pubsub",
+			Topic:      "checkout",
+			Routes: routes{
+				Default: "/orders",
+			},
+      Metadata: map[string]string{
+        "maxPriority": "3"
+      },
+		},
+	}
+
+	w.WriteHeader(http.StatusOK)
+	json.NewEncoder(w).Encode(t)
+}
+```
+{{% /codetab %}}
+
+{{< /tabs >}}
+
+### Setting a priority when publishing a message
+
+To set a priority on a message, add the publish metadata key `maxPriority` to the publish endpoint or SDK method.
+
+{{< tabs "HTTP API (Bash)" Python JavaScript Go>}}
+
+{{% codetab %}}
+
+```bash
+curl -X POST http://localhost:3601/v1.0/publish/order-pub-sub/orders?metadata.maxPriority=3 -H "Content-Type: application/json" -d '{"orderId": "100"}'
+```
+
+{{% /codetab %}}
+
+{{% codetab %}}
+
+```python
+with DaprClient() as client:
+        result = client.publish_event(
+            pubsub_name=PUBSUB_NAME,
+            topic_name=TOPIC_NAME,
+            data=json.dumps(orderId),
+            data_content_type='application/json',
+            metadata= { 'maxPriority': '3' })
+```
+
+{{% /codetab %}}
+
+{{% codetab %}}
+
+```javascript
+await client.pubsub.publish(PUBSUB_NAME, TOPIC_NAME, orderId, { 'maxPriority': '3' });
+```
+
+{{% /codetab %}}
+
+{{% codetab %}}
+
+```go
+client.PublishEvent(ctx, PUBSUB_NAME, TOPIC_NAME, []byte(strconv.Itoa(orderId)), map[string]string{"maxPriority": "3"})
+```
+{{% /codetab %}}
+
+{{< /tabs >}}
+
 ## Related links
 
 - [Basic schema for a Dapr component]({{< ref component-schema >}}) in the Related links section