UAOOI.Networking.UDPMessageHandler 4.0.2

Reactive Networking of Semantic-Data Underlying Transport over UDP

Motivation

The main goal of this document is to provide instruction on how to expand the transport layer for OOI Networking of the Semantic-Data over the User Datagram Protocol (UDP) to be compliant with the specifications mentioned in the section Normative references. Detailed description of this concept is covered by the document: Reactive Networking of Semantic-Data Library

A reference implementation of the Transport over UDP is provided by the project Networking.UDPMessageHandler. Because intentionally the SDK is designed to use any transport protocol, a custom external component implementing UDP connectivity can be seamlessly integrated with this SDK using dependency injection concept.

Normative References

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application.

• Internet Standard RFC 768: User Datagram Protocol (UDP)l
• Internet Standard RFC: 791 Internet Protocol (IP)
• Internet Standard RFC 1112 Host Extensions for IP Multicasting
• OPC Unified Architecture Specification Part 14: PubSub Release 1.04 February 06, 2018

Notices for Implementer

The article Reactive Networking of Semantic-Data Library contains a description covering instruction for the external UDP handling components. An example of how to implement the Transport layer for the UDP protocol is illustrated by the project UA Data Example Application. This library implements the IMessageHandlerFactory in the class MessageHandlerFactory used to create communication infrastructure for the Consumer and Producer role as well.

The JoinMulticastGroup method subscribes the UdpClient to a multicast group using the specified IPAddress. After calling the JoinMulticastGroup method, the underlying Socket sends an Internet Group Management Protocol (IGMP) packet to the router requesting membership to the multicast group. The multicast address range is 224.0.0.0 to 239.255.255.255. If you specify an address outside this range or if the router to which the request is made is not multicast enabled, UdpClient will throw a SocketException. Once the UdpClient is listed with the router as a member of the multicast group, it will be able to receive multicasted datagrams sent to the specified IPAddress. Publisher do not need to belong to a multicast group to send datagrams to a multicast IP address. To get more details visit the MSDN online documentation.