CoAP Class

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

Syntax

ipworksiot.CoAP

Remarks

The CoAP class provides a lightweight, fully-featured CoAP client and server implementation with DTLS support.

Using the Class in Client Mode

While in client mode (i.e., the Listening property is disabled; its default setting), the class 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.

By default, the component operates in NoSec mode as defined by RFC 7252. Certificate mode DTLS can be enabled by setting SSLEnabled to True. UseRawPublicKey can be used to enable Raw Public Key mode.

When DTLS is enabled, relevant handshake details will be reported by the SSLStatus event. Initially, the server will present its certificate to the client. The certificate is validated by the system and the status is provided within the SSLServerAuthentication event. If the Accept parameter of the SSLServerAuthentication event is false, the Status parameter will tell you why. You can then set the Accept parameter to true to manually force acceptance of the server certificate.

In some cases, the server requires the client to present a certificate as well. In this case, a valid certificate will need to be specified via the SSLCert property. This process may look like the following:

coapclient.OnSSLServerAuthentication += (o, e) => { if (e.Accept) return; Console.Write("Server provided the following certificate:\nIssuer: " + e.CertIssuer + "\nSubject: " + e.CertSubject + "\n"); Console.Write("The following problems have been determined for this certificate: " + e.Status + "\n"); Console.Write("Would you like to accept anyways? [y/n] "); if (Console.Read() == 'y') e.Accept = true; }; coapclient.SSLEnabled = true; coapclient.RemoteHost = "remote_ip"; coapclient.RemotePort = 1234; coapclient.Timeout = 30; // if client authentication is applicable coapclient.SSLCert = new Certificate("/path/to/cert.pfx", CertStoreTypes.cstPFXFile, "cert_password", "cert_subject"); To send a request, populate the RequestData, RequestContentFormat, RequestETag, and RequestOptions 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 ResponseOptions 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.) coap.OnRequestComplete += (s, e) => { Console.WriteLine("Request complete!"); Console.WriteLine(coap.ResponseCode); }; // Make a GET request to download a picture. coap.Get("coap://mycoapserver/pictures/animals/cats4.dat?format=png"); // Imaginary function which accepts PNG image data and displays the picture to the user. showPicture(coap.ResponseDataB);

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 ResponseOptions 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. coap.OnNotification += (s, e) => { // Notifications can arrive out of order; only print to the log if this is the latest one we've received. if (e.IsLatest) { Console.WriteLine("Received notification for the resource at: " + e.URI); Console.WriteLine("New Value: " + coap.ResponseData); } } // Start observing a temperature sensor's data. Assume temperature values are sent back in text format. coap.StartObserving("coap://mycoapserver/home/living_room/sensors/temperature?unit=fahrenheit"); // Assume the server accepts the request and starts sending notifications every so often. // ... // Later, stop observing the resource. coap.StopObserving("coap://mycoapserver/home/living_room/sensors/temperature?unit=fahrenheit");

Using the Class in Server Mode

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

By default, the component operates in NoSec mode as defined by RFC 7252. Certificate mode DTLS can be enabled by setting SSLEnabled to True. UseRawPublicKey can be used to enable Raw Public Key mode.

When DTLS is enabled, a valid certificate must be selected before the server can start listening for incoming connections. The certificate can be specified via the SSLCert property. Note the certificate must contain a private key.

After doing so, calling StartListening will cause the class to start listening for incoming connections. The class will listen on the interface defined by LocalHost and LocalPort, if specified. Otherwise, these values will be set by the class. If applicable, these values must be set before calling StartListening. For example:

//coapserver.LocalHost = "some_ip_address"; //coapserver.LocalPort = 1234; coapserver.SSLCert = new Certificate("/path/to/cert.pfx", CertStoreTypes.cstPFXFile, "cert_password", "cert_subject"); coapserver.StartListening(); Console.WriteLine("Listening on: " + coapserver.LocalHost + ":" + coapserver.LocalPort); while (coapserver.Listening) { coapserver.DoEvents(); }

A response can be sent by populating the ResponseCode, ResponseData, ResponseContentFormat, ResponseETag, and ResponseOptions 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. coap.OnRequest += (s, e) => { // For the purpose of this snippet, assume we only service GET requests, which have a method code of 1. if (e.Method == 1) { Console.WriteLine("GET request received for URI path: " + e.URIPath + " and URI query params: " + e.URIQuery); coap.ResponseCode = "2.05"; // "Content". // Imaginary methods that look up the data and content format of the resource based on the URI path and URI query parameters. coap.ResponseData = lookupResourceData(e.URIPath, e.URIQuery); coap.ResponseContentFormat = lookupResourceContentFormat(e.URIPath, e.URIQuery); } else { coap.ResponseCode = "4.05"; // "Method Not Allowed". coap.ResponseData = "Only GET requests are allowed."; // Include a diagnostic payload. coap.ResponseContentFormat = ""; } // Alternatively, this event could simply save the e.RequestId value somewhere, then some other code could fill in the Response* // properties and call the SendResponse() method later. }; coap.OnResponseComplete += (s, e) => { Console.WriteLine("Response sent for request with Id " + e.RequestId); };

In server mode, the class 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 class to accept the registration.

To notify clients that a resource has changed, populate the ResponseCode, ResponseData, ResponseContentFormat, ResponseETag, and ResponseOptions 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. coap.OnRegister += (s, e) => { Console.WriteLine("Client " + e.RemoteHost + ":" + e.RemotePort + " has registered for notifications for the URI " + e.URI); // Imaginary method that helps ensure the application keeps track of observed URIs. The class itself maintains the // list of observers for each URI, so the application just needs to know that there are observers in the first place. observerRegisteredForURI(e.URI); e.Accept = true; }; coap.OnUnregistered += (s, e) => { Console.WriteLine("Client " + e.RemoteHost + ":" + e.RemotePort + " has unregistered from notifications for the URI " + e.URI); // As above, imaginary method that helps ensure the application keeps track of observed URIs. observerUnregisteredForURI(e.URI); }; // Somewhere else in the application, this sort of code might get called after a resource changes to inform any observers of // the change. We use another imaginary method here to check if the changed resource is observed, and to get its information. if (isResourceObserved()) { coap.ResponseCode = "2.05"; // "Content". coap.ResponseDataB = getResourceContent(); coap.ResponseContentFormat = getResourceContentFormat(); coap.SendNotification(getResourceURI()); }

Property List

The following is the full list of the properties of the class with short descriptions. Click on the links for further details.

Method List

The following is the full list of the methods of the class with short descriptions. Click on the links for further details.

Event List

The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.

Config Settings

The following is a list of config settings for the class with short descriptions. Click on the links for further details.

Listening Property (CoAP Class)

Whether the class should operate in server mode by listening for incoming requests.

Syntax

public boolean isListening();


public void setListening(boolean listening);

Default Value

False

Remarks

This property indicates whether the class operates in server mode or client mode.

When this property is false (default), the class operate in client mode, allowing applications to send requests using the Get, Post, SendCustomRequest, etc. methods.

When this property is true, the class listens on LocalPort for incoming CoAP requests, firing the Request event anytime one arrives. Applications can service these requests directly during Request events, or send separate responses later using the SendResponse method.

Applications that wish to use the class in server mode should set the LocalPort property to the desired listening port (such as 5683, the standard CoAP port) before calling StartListening. Otherwise the system will choose a port at random.

Use the StartListening and StopListening methods to control whether the class is listening.

This property is not available at design time.

LocalHost Property (CoAP Class)

This property includes the name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax

public String getLocalHost();


public void setLocalHost(String localHost);

Default Value

""

Remarks

The LocalHost property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multihomed hosts (machines with more than one IP interface) setting LocalHost to the IP address of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface. It is recommended to provide an IP address rather than a hostname when setting this property to ensure the desired interface is used.

If the class is connected, the LocalHost property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multihomed hosts (machines with more than one IP interface).

Note: LocalHost is not persistent. You must always set it in code, and never in the property window.

LocalPort Property (CoAP Class)

This property includes the User Datagram Protocol (UDP) port in the local host where UDP binds.

Syntax

public int getLocalPort();


public void setLocalPort(int localPort);

Default Value

0

Remarks

The LocalPort property must be set before UDP is activated (Active is set to True). This instructs the class to bind to a specific port (or communication endpoint) in the local machine.

Setting it to 0 (default) enables the Transmission Control Protocol (TCP)/IP stack to choose a port at random. The chosen port will be shown by the LocalPort property after the connection is established.

LocalPort cannot be changed once the class is Active. Any attempt to set the LocalPort property when the class is Active will generate an error.

The LocalPort property is useful when trying to connect to services that require a trusted port on the client side.

PendingRequests Property (CoAP Class)

Collection of pending requests.

Syntax

public CoAPRequestMap getPendingRequests();

Remarks

This collection property holds a list of CoAPRequest items.

When the class is operating in client mode (i.e., the Listening property is disabled), each item represents an outgoing request for which a response has not yet been received.

When the class is operating in server mode (i.e., the Listening property is enabled), each item represents an incoming request for which a response has not yet been sent.

This property is read-only and not available at design time.

RequestContentFormat Property (CoAP Class)

The request content format.

Syntax

public int getRequestContentFormat();


public void setRequestContentFormat(int requestContentFormat);

Default Value

-1

Remarks

When the class is operating in client mode (i.e., the Listening property is disabled), this property specifies the content format that should be included in outgoing requests.

When the class is operating in server mode (i.e., the Listening property is enabled), this property is populated with the content format included in incoming requests (if any) anytime the Request event fires.

In either case, the valid set of values for this property is -1, or a value in the range 0 to 65535. -1 prevents a Content-Format option from being included when sending a request, or indicates that one was not included in a received response.

The following table provides a (non-exhaustive) list of some of the more common content formats; refer to the IANA's CoAP Content-Formats registry for a full list.

This property is not available at design time.

RequestData Property (CoAP Class)

The request data.

Syntax

public byte[] getRequestData();


public void setRequestData(byte[] requestData);

Default Value

""

Remarks

When the class is operating in client mode (i.e., the Listening property is disabled), this property specifies the data that should be included in requests sent using Post, Put, or SendCustomRequest.

When the class is operating in server mode (i.e., the Listening property is enabled), this property is populated with the data included in incoming requests (if any) anytime the Request event fires.

This property is not available at design time.

RequestETag Property (CoAP Class)

The request ETag.

Syntax

public byte[] getRequestETag();


public void setRequestETag(byte[] requestETag);

Default Value

""

Remarks

When the class is operating in client mode (i.e., the Listening property is disabled), this property specifies the ETag that should be included in outgoing requests. Leave it empty to prevent an Etag option from being included.

When the class is operating in server mode (i.e., the Listening property is enabled), this property is populated with the ETag included in incoming requests (if any) anytime the Request event fires. It will be empty if an Etag option was not included.

This property is not available at design time.

RequestOptions Property (CoAP Class)

Collection of request options.

Syntax

public CoAPOptionList getRequestOptions();


public void setRequestOptions(CoAPOptionList requestOptions);

Remarks

This collection property holds a list of CoAPOption items.

When the class is operating in client mode (i.e., the Listening property is disabled), each item represents an option that will be included in the next outgoing request.

When the class is operating in server mode (i.e., the Listening property is enabled), each item represents an option included in the most-recently-received request.

This property is not available at design time.

ResponseCode Property (CoAP Class)

The response code.

Syntax

public String getResponseCode();


public void setResponseCode(String responseCode);

Default Value

""

Remarks

When the class is operating in client mode (i.e., the Listening property is disabled), this property is populated with the response code included in incoming responses anytime the RequestComplete event fires.

When the class is operating in server mode (i.e., the Listening property is enabled), this property specifies the response code that should be included in outgoing responses (regardless of whether they are sent immediately after Request fires, or later using SendResponse or SendNotification).

In either case, the valid set of values for this property are strings of the format c.dd, where c is a class value in the range 2 to 7, and dd is a detail value in the range 00 to 31.

The following table provides a (non-exhaustive) list of some of the more common response codes; refer to the IANA's CoAP Response Codes registry for a full list.

This property is not available at design time.

ResponseContentFormat Property (CoAP Class)

The response content format.

Syntax

public int getResponseContentFormat();


public void setResponseContentFormat(int responseContentFormat);

Default Value

-1

Remarks

When the class is operating in client mode (i.e., the Listening property is disabled), this property is populated with the content format included in incoming responses anytime the RequestComplete event fires.

When the class is operating in server mode (i.e., the Listening property is enabled), this property specifies the content format that should be included in outgoing responses (regardless of whether they are sent immediately after Request fires, or later using SendResponse or SendNotification).

In either case, the valid set of values for this property is -1, or a value in the range 0 to 65535. -1 prevents a Content-Format option from being included when sending a response, or indicates that one was not included in a received response.

The following table provides a (non-exhaustive) list of some of the more common content formats; refer to the IANA's CoAP Content-Formats registry for a full list.

This property is not available at design time.

ResponseData Property (CoAP Class)

The response data.

Syntax

public byte[] getResponseData();


public void setResponseData(byte[] responseData);

Default Value

""

Remarks

When the class is operating in client mode (i.e., the Listening property is disabled), this property is populated with the data included in incoming responses (if any) anytime the RequestComplete event fires.

When the class is operating in server mode (i.e., the Listening property is enabled), this property specifies the data that should be included in outgoing responses (regardless of whether they are sent immediately after Request fires, or later using SendResponse or SendNotification).

This property is not available at design time.

ResponseETag Property (CoAP Class)

The response ETag.

Syntax

public byte[] getResponseETag();


public void setResponseETag(byte[] responseETag);

Default Value

""

Remarks

When the class is operating in client mode (i.e., the Listening property is disabled), this property is populated with the ETag included in incoming responses (if any) anytime the RequestComplete event fires. It will be empty if an Etag option was not included.

When the class is operating in server mode (i.e., the Listening property is enabled), this property specifies the ETag that should be included in outgoing responses (regardless of whether they are sent immediately after Request fires, or later using SendResponse or SendNotification). Leave it empty to prevent an Etag option from being included.

This property is not available at design time.

ResponseOptions Property (CoAP Class)

Collection of response options.

Syntax

public CoAPOptionList getResponseOptions();


public void setResponseOptions(CoAPOptionList responseOptions);

Remarks

This collection property holds a list of CoAPOption items.

When the class is operating in client mode (i.e., the Listening property is disabled), each item represents an option included in the most-recently-received response.

When the class is operating in server mode (i.e., the Listening property is enabled), each item represents an option that will be included in the next outgoing response.

This property is not available at design time.

SSLAcceptServerCert Property (CoAP Class)

This property instructs the class to unconditionally accept the server certificate that matches the supplied certificate.

Syntax

public Certificate getSSLAcceptServerCert();


public void setSSLAcceptServerCert(Certificate SSLAcceptServerCert);

Remarks

If it finds any issues with the certificate presented by the server, the class will normally terminate the connection with an error.

You may override this behavior by supplying a value for SSLAcceptServerCert. If the certificate supplied in SSLAcceptServerCert is the same as the certificate presented by the server, then the server certificate is accepted unconditionally, and the connection will continue normally.

Note: This functionality is provided only for cases in which you otherwise know that you are communicating with the right server. If used improperly, this property may create a security breach. Use it at your own risk.

SSLAuthenticateClients Property (CoAP Class)

If set to True, the server asks the client(s) for a certificate.

Syntax

public boolean isSSLAuthenticateClients();


public void setSSLAuthenticateClients(boolean SSLAuthenticateClients);

Default Value

False

Remarks

This property is used in conjunction with the SSLClientAuthentication event. Please refer to the documentation of the SSLClientAuthentication event for details.

SSLCert Property (CoAP Class)

This property includes the certificate to be used during Secure Sockets Layer (SSL) negotiation.

Syntax

public Certificate getSSLCert();


public void setSSLCert(Certificate SSLCert);

Remarks

This property includes the digital certificate that the class will use during SSL negotiation. Set this property to a valid certificate before starting SSL negotiation. To set a certificate, you may set the Encoded field to the encoded certificate. To select a certificate, use the store and subject fields.

SSLEnabled Property (CoAP Class)

This property indicates whether Transport Layer Security/Secure Sockets Layer (TLS/SSL) is enabled.

Syntax

public boolean isSSLEnabled();


public void setSSLEnabled(boolean SSLEnabled);

Default Value

False

Remarks

This property specifies whether TLS/SSL is enabled in the class. When False (default), the class operates in plaintext mode. When True, TLS/SSL is enabled.

TLS/SSL may also be enabled by setting SSLStartMode. Setting SSLStartMode will automatically update this property value.

This property is not available at design time.

SSLServerCert Property (CoAP Class)

This property includes the server certificate for the last established connection.

Syntax

public Certificate getSSLServerCert();

Remarks

SSLServerCert contains the server certificate for the last established connection.

SSLServerCert is reset every time a new connection is attempted. &

This property is read-only.

Timeout Property (CoAP Class)

A timeout for the class.

Syntax

public int getTimeout();


public void setTimeout(int timeout);

Default Value

60

Remarks

This property specifies the number of seconds that the class should wait, synchronously, for a response to be received. A value of 0 means that the class will send the request data (when operating in client mode) or the response data (when operating in server mode) asynchronously, and then wait indefinitely, firing the applicable event once complete.

The class will use DoEvents to enter an efficient wait loop during any potential waiting period, ensuring that all system events are processed immediately as they arrive. This ensures that the host application does not "freeze" and remains responsive.

If Timeout expires, and the response has not yet been received, the class throws an exception.

UseConfirmableMessages Property (CoAP Class)

Whether to use confirmable message.

Syntax

public boolean isUseConfirmableMessages();


public void setUseConfirmableMessages(boolean useConfirmableMessages);

Default Value

True

Remarks

This property specifies whether the class should send requests (if operating in client mode; i.e., when the Listening property is disabled) or responses (if operating in server mode; i.e., when the Listening property is enabled) using confirmable messages instead of unconfirmable messages.

Using confirmable messages increases reliability, since the class will automatically retransmit a message until it receives a confirmation from the remote host that the message was received. Note that the retransmission period is not infinite; eventually the class will assume that the message is undeliverable and time out the retransmission process.

Using non-confirmable messages reduces the amount of network traffic, but at the cost of reliability, since the class has no way to know whether a given message was received by the remote host, or lost in transit.

CancelRequest Method (CoAP Class)

Cancels a pending request.

Syntax

public void cancelRequest(String requestId);

Remarks

This method cancels the request in the PendingRequests collection identified by RequestId.

When the class is operating in client mode, the requests in the PendingRequests collection represent outgoing requests for which responses have not yet been received. Canceling one will cause the RequestComplete event to fire with an appropriate ErrorCode and ErrorDescription.

When the class is operating in server mode, the requests in the PendingRequests collection represent incoming requests for which responses have not yet been sent. Canceling one will cause the ResponseComplete event to fire with an appropriate ErrorCode and ErrorDescription.

Config Method (CoAP Class)

Sets or retrieves a configuration setting.

Syntax

public String config(String configurationString);

Remarks

Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Delete Method (CoAP Class)

Sends a DELETE request to the server.

Syntax

public String delete(String URI);

Remarks

This method sends the server a DELETE request for the resource identified by URI. If the RequestETag property is non-empty, its value will be used to include an Etag option in the request. Any additional options present in the RequestOptions collection will be included as well.

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.

If the UseConfirmableMessages property is enabled when this method is called, the class will automatically retransmit the request message (if necessary) until it receives confirmation from the server that it was received. Note that the retransmission period is not infinite; eventually the class will assume that the message is undeliverable and time out the request.

If the Timeout property is greater than 0, this method will block until either a response is received, the specified timeout interval elapses, or (if UseConfirmableMessages is enabled) the retransmission period elapses; whichever occurs first. It will then return empty string.

If the Timeout property is 0, a record of the request will be added to the PendingRequests collection, and this method will finish immediately, returning an Id for the request. Passing this Id to the CancelRequest method will cancel the request (assuming it is still pending at that time).

Once a response is received, or the request times out, the class will do the following:

• Populate the Response* properties (unless the request timed out).
• Remove the request record from the PendingRequests collection, if necessary.
• Fire the RequestComplete event.

Note: This method can only be called when the class is operating in client mode (i.e., when the Listening property is disabled).

DoEvents Method (CoAP Class)

This method processes events from the internal message queue.

Syntax

public void doEvents();

Remarks

When DoEvents is called, the class processes any available events. If no events are available, it waits for a preset period of time, and then returns.

Get Method (CoAP Class)

Sends a GET request to the server.

Syntax

public String get(String URI);

Remarks

This method sends the server a GET request for the resource identified by URI. If the RequestETag property is non-empty, its value will be used to include an Etag option in the request. Any additional options present in the RequestOptions collection will be included as well.

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.

If the UseConfirmableMessages property is enabled when this method is called, the class will automatically retransmit the request message (if necessary) until it receives confirmation from the server that it was received. Note that the retransmission period is not infinite; eventually the class will assume that the message is undeliverable and time out the request.

If the Timeout property is greater than 0, this method will block until either a response is received, the specified timeout interval elapses, or (if UseConfirmableMessages is enabled) the retransmission period elapses; whichever occurs first. It will then return empty string.

If the Timeout property is 0, a record of the request will be added to the PendingRequests collection, and this method will finish immediately, returning an Id for the request. Passing this Id to the CancelRequest method will cancel the request (assuming it is still pending at that time).

Once a response is received, or the request times out, the class will do the following:

• Populate the Response* properties (unless the request timed out).
• Remove the request record from the PendingRequests collection, if necessary.
• Fire the RequestComplete event.

Note: This method can only be called when the class is operating in client mode (i.e., when the Listening property is disabled).

Post Method (CoAP Class)

Sends a POST request to the server.

Syntax

public String post(String URI);

Remarks

This method sends the server a POST request for the resource identified by URI. The RequestData property specifies the data that will be sent in the request. If the RequestContentFormat and/or RequestETag properties are non-empty, their values will be used to include Content-Format and Etag options in the request (respectively). Any additional options present in the RequestOptions collection will be included as well.

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.

If the UseConfirmableMessages property is enabled when this method is called, the class will automatically retransmit the request message (if necessary) until it receives confirmation from the server that it was received. Note that the retransmission period is not infinite; eventually the class will assume that the message is undeliverable and time out the request.

If the Timeout property is greater than 0, this method will block until either a response is received, the specified timeout interval elapses, or (if UseConfirmableMessages is enabled) the retransmission period elapses; whichever occurs first. It will then return empty string.

If the Timeout property is 0, a record of the request will be added to the PendingRequests collection, and this method will finish immediately, returning an Id for the request. Passing this Id to the CancelRequest method will cancel the request (assuming it is still pending at that time).

Once a response is received, or the request times out, the class will do the following:

• Populate the Response* properties (unless the request timed out).
• Remove the request record from the PendingRequests collection, if necessary.
• Fire the RequestComplete event.

Note: This method can only be called when the class is operating in client mode (i.e., when the Listening property is disabled).

Put Method (CoAP Class)

Sends a PUT request to the server.

Syntax

public String put(String URI);

Remarks

This method sends the server a PUT request for the resource identified by URI. The RequestData property specifies the data that will be sent in the request. If the RequestContentFormat and/or RequestETag properties are non-empty, their values will be used to include Content-Format and Etag options in the request (respectively). Any additional options present in the RequestOptions collection will be included as well.

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.

If the UseConfirmableMessages property is enabled when this method is called, the class will automatically retransmit the request message (if necessary) until it receives confirmation from the server that it was received. Note that the retransmission period is not infinite; eventually the class will assume that the message is undeliverable and time out the request.

If the Timeout property is greater than 0, this method will block until either a response is received, the specified timeout interval elapses, or (if UseConfirmableMessages is enabled) the retransmission period elapses; whichever occurs first. It will then return empty string.

If the Timeout property is 0, a record of the request will be added to the PendingRequests collection, and this method will finish immediately, returning an Id for the request. Passing this Id to the CancelRequest method will cancel the request (assuming it is still pending at that time).

Once a response is received, or the request times out, the class will do the following:

• Populate the Response* properties (unless the request timed out).
• Remove the request record from the PendingRequests collection, if necessary.
• Fire the RequestComplete event.

Note: This method can only be called when the class is operating in client mode (i.e., when the Listening property is disabled).

Reset Method (CoAP Class)

This method will reset the class.

Syntax

public void reset();

Remarks

This method will reset the class's properties to their default values.

SendCustomRequest Method (CoAP Class)

Sends a custom request to the server.

Syntax

public String sendCustomRequest(String URI, int method);

Remarks

This method sends the server a custom request for the resource identified by URI. The Method parameter specifies the request's method code. The following table provides a (non-exhaustive) list of some of the more common method codes; refer to the IANA's CoAP Method Codes registry for a full list.

The RequestData property specifies the data that will be sent in the request. If the RequestContentFormat and/or RequestETag properties are non-empty, their values will be used to include Content-Format and Etag options in the request (respectively). Any additional options present in the RequestOptions collection will be included as well.

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.

If the UseConfirmableMessages property is enabled when this method is called, the class will automatically retransmit the request message (if necessary) until it receives confirmation from the server that it was received. Note that the retransmission period is not infinite; eventually the class will assume that the message is undeliverable and time out the request.

If the Timeout property is greater than 0, this method will block until either a response is received, the specified timeout interval elapses, or (if UseConfirmableMessages is enabled) the retransmission period elapses; whichever occurs first. It will then return empty string.

If the Timeout property is 0, a record of the request will be added to the PendingRequests collection, and this method will finish immediately, returning an Id for the request. Passing this Id to the CancelRequest method will cancel the request (assuming it is still pending at that time).

Once a response is received, or the request times out, the class will do the following:

• Populate the Response* properties (unless the request timed out).
• Remove the request record from the PendingRequests collection, if necessary.
• Fire the RequestComplete event.

Note: This method can only be called when the class is operating in client mode (i.e., when the Listening property is disabled).

SendNotification Method (CoAP Class)

Sends a notification to all clients observing a given resource.

Syntax

public void sendNotification(String URI);

Remarks

This method sends a notification to all clients observing the resource identified by URI, notifying them of its latest state. Clients should be notified whenever a resource's content changes (or periodically, if it changes very often) by sending a 2.xx response code; typically 2.03 "Valid" or 2.05 "Content". Clients should also be notified if a resource can no longer be observed (e.g., when it is deleted) by sending a notification with a non-2.xx response code (e.g., 4.04 "Not Found"). The class will automatically unregister all observers when a non-2.xx notification is sent.

The ResponseData property specifies the data that will be sent in the response, and the ResponseCode property specifies the response code. If the ResponseContentFormat and/or ResponseETag properties are non-empty, their values will be used to include Content-Format and Etag options in the response (respectively). Any additional options present in the ResponseOptions collection will be included as well.

If the UseConfirmableMessages property is enabled when this method is called, the class will automatically retransmit the response message (if necessary) until it receives confirmation from the client that it was received. Note that the retransmission period is not infinite; eventually the class will assume that the message is undeliverable and time out the response.

Note: This method can only be called when the class is operating in server mode (i.e., when the Listening property is enabled).

SendResponse Method (CoAP Class)

Sends a response for a given pending request to the corresponding client.

Syntax

public void sendResponse(String requestId);

Remarks

This method sends a response for the request in the PendingRequests collection identified by RequestId. The ResponseData property specifies the data that will be sent in the response, and the ResponseCode property specifies the response code. If the ResponseContentFormat and/or ResponseETag properties are non-empty, their values will be used to include Content-Format and Etag options in the response (respectively). Any additional options present in the ResponseOptions collection will be included as well.

If the UseConfirmableMessages property is enabled when this method is called, the class will automatically retransmit the response message (if necessary) until it receives confirmation from the client that it was received. Note that the retransmission period is not infinite; eventually the class will assume that the message is undeliverable and time out the response. The ResponseComplete event will fire once the message receipt is confirmed (or once the retransmission period elapses).

If the UseConfirmableMessages property is disabled, the ResponseComplete event will fire immediately instead, since there is no way to know whether the client received the response.

Note: This method can only be called when the class is operating in server mode (i.e., when the Listening property is enabled).

StartListening Method (CoAP Class)

This method starts listening for incoming connections.

Syntax

public void startListening();

Remarks

This method begins listening for incoming connections on the port specified by LocalPort. Once listening, events will fire as new clients connect and data are transferred.

To stop listening for new connections, call StopListening. To stop listening for new connections and to disconnect all existing clients, call Shutdown.

StartObserving Method (CoAP Class)

Registers the class as an observer for a given resource.

Syntax

public String startObserving(String URI);

Remarks

This method registers the class as an observer for the resource identified by URI. If the server accepts the registration, then it will periodically notify the class about any changes to the specified resource. These "change notifications" are exposed via the Notification event.

This method operates in the exact same manner as the Get method, with the exception of the two things listed below. Refer to the Get method's documentation for more information.

1. When constructing the request, the class automatically includes an Observe option. The presence of this option is what indicates to the server that the class wishes to register itself as an observer for the specified resource.
2. When the server receives the request, its response causes the Notification event to fire instead of the RequestComplete event. (Unless it decides to reject the registration, in which case it will handle the request just like a normal GET request, and the RequestComplete event will fire when its response is received, just like it would if Get had been called.)

Once the class has successfully registered itself as an observer, the server will continue to deliver change notifications for the specified resource until the class unregisters, or the resource can no longer be observed (e.g., if it is deleted). To unregister, either call the StopObserving method with the same URI value, or set the Notification event's StopObserving parameter to True.

Note: This method can only be called when the class is operating in client mode (i.e., when the Listening property is disabled).

StopListening Method (CoAP Class)

This method stops listening for new connections.

Syntax

public void stopListening();

Remarks

This method stops listening for new connections. After being called, any new connection attempts will be rejected. Calling this method does not disconnect existing connections.

To stop listening and to disconnect all existing clients, call Shutdown instead.

StopObserving Method (CoAP Class)

Unregisters the class as an observer for a given resource.

Syntax

public void stopObserving(String URI);

Remarks

This method unregisters the class as an observer for the resource identified by URI. This method operates in the exact same manner as the Get method, with the exception of the two things below; refer to the Get method's documentation for more information:

1. When constructing the request, the class automatically includes an Observe option with a value of 1. The presence of this option indicates to the server that the class wishes to unregister from further change notifications.
2. This method, unlike Get, does not return a request Id.

Note: This method can only be called when the class is operating in client mode (i.e., when the Listening property is disabled).

Error Event (CoAP Class)

Fired when information is available about errors during data delivery.

Syntax

public class DefaultCoAPEventListener implements CoAPEventListener {
  ...
  public void error(CoAPErrorEvent e) {}
  ...
}

public class CoAPErrorEvent {
  public int errorCode;
  public String description;
}

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class throws an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Log Event (CoAP Class)

Fires once for each log message.

Syntax

public class DefaultCoAPEventListener implements CoAPEventListener {
  ...
  public void log(CoAPLogEvent e) {}
  ...
}

public class CoAPLogEvent {
  public int logLevel;
  public String message;
}

Remarks

This event fires once for each log message generated by the class. The verbosity is controlled by the LogLevel setting.

LogLevel indicates the level of the Message. Possible values are:

Notification Event (CoAP Class)

Fires when a notification is received from the server.

Syntax

public class DefaultCoAPEventListener implements CoAPEventListener {
  ...
  public void notification(CoAPNotificationEvent e) {}
  ...
}

public class CoAPNotificationEvent {
  public String URI;
  public boolean isLatest;
  public boolean stopObserving; //read-write
}

Remarks

This event fires when the class receives a notification from that server that some observed resource has changed. Query the ResponseCode, ResponseData, ResponseContentFormat, ResponseETag, and ResponseOptions properties to obtain the new resource information.

Note that, in some cases, the server may no longer be able to deliver notifications for a resource (e.g., if it is deleted). In such cases, the ResponseCode property will be populated with a non-2.xx code (e.g., 4.04 "Not Found") to indicate why the resource can no longer be observed. No further notifications will be delivered for the resource after such a notification arrives.

The URI parameter identifies the resource that has changed.

The IsLatest parameter reflects whether this notification actually has the most recent resource information available, since it is possible for notifications to arrive out of order under certain circumstances.

The StopObserving parameter specifies whether the class should stop observing the resource identified by URI. This parameter is False by default, set it to True to have the class unregister itself from further notifications. (Note: in the event of a non-2.xx notification, this parameter will be True by default instead, and changing it to False will have no effect.)

Note: This event is only used when the class is operating in client mode (i.e., when the Listening property is disabled).

Register Event (CoAP Class)

Fires when a client wishes to register for notifications.

Syntax

public class DefaultCoAPEventListener implements CoAPEventListener {
  ...
  public void register(CoAPRegisterEvent e) {}
  ...
}

public class CoAPRegisterEvent {
  public String remoteHost;
  public int remotePort;
  public String URI;
  public String URIHost;
  public int URIPort;
  public String URIPath;
  public String URIQuery;
  public byte[] token;
  public boolean accept; //read-write
}

Remarks

This event fires anytime a client wishes to register itself as an observer for the resource identified by URI. Refer to the StartObserving and SendNotification methods, as well as the Notification event, for more information about observing resources and resource change notifications.

Any options included in the request can be obtained by querying the RequestOptions collection.

To correctly handle this event, populate the ResponseCode, ResponseData, ResponseContentFormat, ResponseETag, and ResponseOptions properties as desired before this event finishes. (This must be done regardless of the Accept parameter's final value; see below for more information on why).

The RemoteHost parameter reflects the client's IP address or hostname.

The RemotePort parameter reflects the client's port.

The URI parameter reflects the exact resource URI that the client wishes to observe (the CoAP specification states that the full URI must be used to track observers). This value must be passed exactly as-is to the SendNotification method to notify observers of changes to the resource.

The URIHost, URIPort, URIPath, and URIQuery parameters are provided for additional convenience

The Token parameter reflects the token included in the registration request.

The Accept parameter specifies whether the class should accept the registration. By default, it is False, and the request will be treated like a normal GET request. Setting it to True will cause the class to add the client to its internal list of registered observers for the specified URI.

Note: This event is only used when the class is operating in server mode (i.e., when the Listening property is enabled).

Request Event (CoAP Class)

Fires when a request is received from a client.

Syntax

public class DefaultCoAPEventListener implements CoAPEventListener {
  ...
  public void request(CoAPRequestEvent e) {}
  ...
}

public class CoAPRequestEvent {
  public String remoteHost;
  public int remotePort;
  public int method;
  public String URIHost;
  public int URIPort;
  public String URIPath;
  public String URIQuery;
  public byte[] token;
  public String requestId;
  public boolean sendResponse; //read-write
}

Remarks

This event fires anytime a request is received from a client. Information about the request is exposed both via this event's parameters and the following properties: RequestData, RequestContentFormat, RequestETag, and RequestOptions.

A response can either be sent back to the client immediately when the event finishes, or later using the SendResponse method. Refer to the RequestId and SendResponse parameters' documentation, below, for more information. If a response is to be sent back immediately, populate the ResponseCode, ResponseData, ResponseContentFormat, ResponseETag, and ResponseOptions properties as desired before this event finishes.

The RemoteHost parameter reflects the client's IP address or hostname.

The RemotePort parameter reflects the client's port.

The Method parameter reflects the request method code. The following table provides a (non-exhaustive) list of some of the more common method codes; refer to the IANA's CoAP Method Codes registry for a full list.

The URIHost, URIPort, URIPath, and URIQuery parameters, when taken together, identify the resource that the client is making a request against. This event exposes the URI in pieces for convenience.

The Token parameter reflects the token included in the request.

The RequestId parameter reflects the class-generated Id for the request. If the final value of the SendResponse parameter is False, this Id can be passed to the SendResponse method later to send a response. (Alternatively, it can be passed to the CancelRequest later to ignore the request.)

The SendResponse parameter specifies whether the class should send a response back to the client immediately; it is True by default. Set it to False to send the response later instead.

Note: This event is only used when the class is operating in server mode (i.e., when the Listening property is enabled).

RequestComplete Event (CoAP Class)

Fires when a request completes.

Syntax

public class DefaultCoAPEventListener implements CoAPEventListener {
  ...
  public void requestComplete(CoAPRequestCompleteEvent e) {}
  ...
}

public class CoAPRequestCompleteEvent {
  public int method;
  public String URI;
  public String requestId;
  public int errorCode;
  public String errorDescription;
}

Remarks

This event fires when a request completes. Usually, a request is considered complete when a response has been received. However, requests can also be considered "complete" if either of the following occurs:

• If the UseConfirmableMessages property is enabled, and the class did not receive confirmation that the request was received before the retransmission period elapsed.
• If Timeout property is greater than 0, and the class did not receive a response before the timeout period elapsed.

Assuming a response was received (i.e., the ErrorCode parameter is either 0 or 709; see below), then the response code, payload, and options can be obtained by querying the ResponseCode, ResponseData, ResponseContentFormat, ResponseETag, and ResponseOptions properties.

The Method parameter reflects the request method code. The following table provides a (non-exhaustive) list of some of the more common method codes; refer to the IANA's CoAP Method Codes registry for a full list.

The URI parameter reflects the requested resource's URI.

The ErrorCode parameter indicates whether the request encountered an error. If no error was encountered, it will be 0; if the server returned a non-2.xx response code, it will be 709; if some other error occurred (e.g., the request timed out), it will be another non-zero value.

The ErrorDescription parameter provides a description of the error that occurred (or, if ErrorCode is 709, a string version of the response code returned by the server). It will be empty if no error was encountered.

Note: This event is only used when the class is operating in client mode (i.e., when the Listening property is disabled).

ResponseComplete Event (CoAP Class)

Fires when a response has been sent to a client.

Syntax

public class DefaultCoAPEventListener implements CoAPEventListener {
  ...
  public void responseComplete(CoAPResponseCompleteEvent e) {}
  ...
}

public class CoAPResponseCompleteEvent {
  public String requestId;
  public int errorCode;
  public String errorDescription;
}

Remarks

This event fires anytime a response has been sent to a client. If the UseConfirmableMessages property is enabled, then the response is considered complete once the client has confirmed that it received the response (or once the retransmission period elapses). If the UseConfirmableMessages property is disabled, the response is considered complete immediately (since there is no way to know if the client received it).

The RequestId parameter reflects the class-generated Id of the request for which the response was sent.

The ErrorCode parameter indicates whether the response encountered an error (e.g., transmission timed out). If no error was encountered, it will be 0.

The ErrorDescription parameter provides a description of the error that occurred. It will be empty if no error was encountered.

Note: This event is only used when the class is operating in server mode (i.e., when the Listening property is enabled).

SSLClientAuthentication Event (CoAP Class)

This event is fired when the client presents its credentials to the server.

Syntax

public class DefaultCoAPEventListener implements CoAPEventListener {
  ...
  public void SSLClientAuthentication(CoAPSSLClientAuthenticationEvent e) {}
  ...
}

public class CoAPSSLClientAuthenticationEvent {
  public String connectionId;
  public byte[] certEncoded;
  public String certSubject;
  public String certIssuer;
  public String status;
  public boolean accept; //read-write
}

Remarks

This event enables the server to decide whether or not to continue. The Accept parameter is a recommendation on whether to continue or to close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string "OK").

SSLServerAuthentication Event (CoAP Class)

Fired after the server presents its certificate to the client.

Syntax

public class DefaultCoAPEventListener implements CoAPEventListener {
  ...
  public void SSLServerAuthentication(CoAPSSLServerAuthenticationEvent e) {}
  ...
}

public class CoAPSSLServerAuthenticationEvent {
  public byte[] certEncoded;
  public String certSubject;
  public String certIssuer;
  public String status;
  public boolean accept; //read-write
}

Remarks

During this event, the client can decide whether or not to continue with the connection process. The Accept parameter is a recommendation on whether to continue or close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string OK). If it is decided to continue, you can override and accept the certificate by setting the Accept parameter to True.

SSLStatus Event (CoAP Class)

Fired when secure connection progress messages are available.

Syntax

public class DefaultCoAPEventListener implements CoAPEventListener {
  ...
  public void SSLStatus(CoAPSSLStatusEvent e) {}
  ...
}

public class CoAPSSLStatusEvent {
  public String message;
}

Remarks

The event is fired for informational and logging purposes only. This event tracks the progress of the connection.

Unregistered Event (CoAP Class)

Fires when a client has unregistered from notifications.

Syntax

public class DefaultCoAPEventListener implements CoAPEventListener {
  ...
  public void unregistered(CoAPUnregisteredEvent e) {}
  ...
}

public class CoAPUnregisteredEvent {
  public String remoteHost;
  public int remotePort;
  public String URI;
  public String URIHost;
  public int URIPort;
  public String URIPath;
  public String URIQuery;
}

Remarks

This event fires anytime a client has unregistered itself from further notifications for the resource identified by URI. Refer to the StartObserving and SendNotification methods, as well as the Notification and Register events, for more information about observing resources and resource change notifications.

The RemoteHost parameter reflects the client's IP address or hostname.

The RemotePort parameter reflects the client's port.

The URI parameter identifies the resource that the client has stopped observing.

The URIHost, URIPort, URIPath, and URIQuery parameters are provided for additional convenience

Note: This event is only used when the class is operating in server mode (i.e., when the Listening property is enabled).

Certificate Type

This is the digital certificate being used.

Remarks

This type describes the current digital certificate. The certificate may be a public or private key. The fields are used to identify or select certificates.

Fields

Constructors

public Certificate();

public Certificate( certificateFile);

public Certificate( encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

CoAPOption Type

A CoAP option.

Remarks

This type represents a CoAP option.

Fields

Constructors

public CoAPOption();

public CoAPOption( number,  value);

CoAPRequest Type

A pending CoAP request.

Remarks

This type represents a pending CoAP request.

Fields

Config Settings (CoAP Class)

CoAP Config Settings

SSL Config Settings

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
... Intermediate Cert ...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
... Root Cert ...
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
... Intermediate Cert ...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
... Root Cert ...
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
... Intermediate Cert...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
... Root Cert...
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

UDP Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (CoAP Class)

CoAP Errors