To use XMPP, you also need to select an XMPP broker. You have to choose if you want to host your own XMPP server under your own domain name or use a publicly available XMPP broker. There are many to choose from.
For a short list of XMPP server software, you can use to set up your own domain, visit https://xmpp.org/software/servers.html. To find a publicly available XMPP server, visit https://www.google.se/search?source=hp&q=public+xmpp+server.
In this book, we will use the XMPP broker available at waher.se. While not necessary for this chapter, it will help us in later chapters when we introduce provisioning.
Readers of this book can request an account at https://waher.se/Broker.md and https://waher.se/RequestAccount.md. Don't forget to mention this book in the registration. Classes and organizations can request API keys at https://waher.se/RequestApiKey.md. This will allow them to automatically generate a given number of accounts securely. Please allow some time for the application to be processed.