Subscribing to topics

Prerequisites

• You must have a secure WebSocket connection to the switch.
• Access to the switch REST API must be enabled. The REST API access mode can be either read-only or read/write.

Procedure

Using the WebSocket secure connection, send a subscribe message that contains the topics to which you want to subscribe and a poll interval hint, if any.

Some resource attributes—typically in the statistics category—are not populated until a client requests the information. The value ofhintspecifies how often—in seconds—the notification subsystem is to request information about the topics in the list.

For example:

{ "type": "subscribe", "topics": [ { "name": "/rest/v1/system/vrfs" }, { "name": "/rest/v1/system/vlans/1?attributes=admin,oper_state_reason" } ], "hint": 5 }

If the subscriber already has a subscription to the specified topic, the following error is returned:

{ "type":"error", "message":"The topic or combination of topics have been already subscribed." }

If the URI in the topic name specifies a resource that is not in the configuration and state database, the following error is returned:

{"type":"error","message":"Object not found."}

Example of a message returned by a successful subscription attempt:

{ "type": "success", "subscriber_name": "4bcf8uka90ki", "subscription_name": "ns83n58dky", "data": [ { "topicname": "/rest/v1/system/vlans/1?attributes=admin,oper_state_reason", "resources": [ { "operation": "", "uri": "/rest/v1/system/vlans/1", "values": { "admin": "up", "oper_state_reason": "no_member_port" } } ] }, { "topicname": "/rest/v1/system/vrfs", "resources": [ { "operation": "", "uri": "/rest/v1/system/vrfs/default", "values": {} }, { "operation": "", "uri": "/rest/v1/system/vrfs/mgmt", "values": {} } ] } ] }