CoAP Component

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An easy-to-use CoAP client and server implementation.

Syntax

TiotCoAP

Remarks

The CoAP component provides a lightweight, fully-featured CoAP client and server implementation.

Using the Component in Client Mode

While in client mode (i.e., the Listening property is disabled; its default setting), the component can be used to send requests to a CoAP server. It can also be used to register as an observer for various server-side resources, causing the server to send notifications anytime said resources change.

To send a request, populate the RequestData, RequestContentFormat, RequestETag, and RequestOption* properties (if necessary, and as applicable), then call one of the following methods:

• Get
• Post
• Put
• Delete
• SendCustomRequest

The methods above require a URI as a parameter. The format of the URI parameter is coap://hostname:port/resource. The port is optional, and if not specified will default to 5683. For instance coap://myserver/test and coap://myserver:5683/test are equivalent.

Once a response is received, the ResponseCode, ResponseData, ResponseContentFormat, ResponseETag, and ResponseOption* properties will be populated, and the RequestComplete event will fire. (If the request times out, the properties are not populated, but the event still fires.)

To observe a resource, call the StartObserving method. Assuming the server accepts the observer registration request, it will begin sending notifications for the resource anytime it changes. Each change notification will cause the ResponseCode, ResponseData, ResponseContentFormat, ResponseETag, and ResponseOption* properties to be populated, and the Notification event to fire.

To stop observing a resource, either call StopObserving with the same URI value used to call StartObserving, or set the Notification event's StopObserving parameter to True.

Using the Component in Server Mode

To operate in server mode, set the LocalPort to the port the component should listen on (typically 5683, the standard CoAP port), then enable the Listening property. Each time a request arrives, the RequestData, RequestContentFormat, RequestETag, and RequestOption* properties will be populated, and the Request event will fire.

A response can be sent by populating the ResponseCode, ResponseData, ResponseContentFormat, ResponseETag, and ResponseOption* properties as desired before the event finishes. Alternatively, the Request event's SendResponse parameter can be set to False in order to send a response back later. In this case, the RequestId value from the event should be used to call the SendResponse method later.

In server mode, the component can also support resource observation. When a client attempts to register itself as an observer of a resource, the Register event will fire; setting this event's Accept parameter to True will cause the component to accept the registration.

To notify clients that a resource has changed, populate the ResponseCode, ResponseData, ResponseContentFormat, ResponseETag, and ResponseOption* properties as desired, and then call the SendNotification method, passing it the URI of a resource that has registered observers.

When a client has unregistered from further change notifications, the Unregistered event will fire.