Hi and Welcome to Steve’s Internet Guide.
In 2011 over 2 billion people where connected to the Internet (Wiki),and over the past 10 years the Internet has become just as important as TV, radio, and the telephone.
Daily internet usage continues to grow and Internet access is vital to our daily lives.
The first wave of the Internet involved connecting people to each other and people to information.
The next wave of the Internet will involve connecting the physical world to the Internet and machines to each other.
Every object, both real and virtual, connected to, and accessible over the Internet is the basic idea of the Internet of Things
or the internet of Everything
About This Site
Although the existing network infrastructure will continue to used, the Internet of things is also going to require a new infrastructure consisting of new protocols, hardware and technologies.
What form this will take is currently unknown but it is likely to take shape over the next 5 years.
The aim of this website is to help you understand the basic technologies and protocols that are used, and that are being developed.
Best Regards Steve
If you have any questions please ask
Normally if a publisher publishes a message to a topic, and no one is subscribed to that topic the message is simply discarded by the broker.
However the publisher can tell the broker to keep the last message on that topic by setting the retained message flag.
This can be very useful, as for example, if you have door sensor publishing its status only when changed, what happens if a new subscriber subscribes to this status? Continue reading
The last will and testament message is used to notify subscribers of an unexpected shutdown of the publisher.
The basic process is.
- The publisher tells the broker to notify all subscribers to a topic, using the last will message , in the event that the connection breaks
- If the broker detects a connection break it send the last will message to all subscribers.
Again you will find more detail in this MQTT essentials article here Continue reading
When a client connects to a broker it can connect using a non persistent connection (clean session) or a persistent connection..
With a non persistent connection the broker doesn’t store any subscription information or undelivered messages for the client.
This mode is ideal when the client only publishes messages.
It can also connect as a durable client using a persistent connection. Continue reading