There are several major systems worth understanding from a higher level. Most of these are documented under specific functions that are critical in those subsystems.
REST calls can be anonymous (or public), or require third-party authentication, i.e. Firebase credentials.
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In the beginning, Tootsville I, the Hillside Demo, there was SmartFox Server. This was a chat server designed to work over an XML protocol with Adobe Flash clients. Tootsville I was built on this SmortFox Server and the SmartFox client software that went with it.
Unfortunately, SFS was not able to scale up with Tootsville's growth, and was very resource-intensive on the server side, so Bruce-Robert Pocock, the Chief Engineer at Res Interactive, brought in a Java-based chat server that he had written, named Braque. Braque was renamed Appius Claudius Caecus, and became the first Roman of the Romance Game System.
In order to convince the SmartFox Client software in the Tootsville Flosh client program (first Nightmare, and later Persephone) to communicate with Appius, we had to advertise a SmartFox version number --- so, in order to ensure that we had a sufficiently high version number, and since EcmaScript uses floating-point numbers, we chose Infinity.
The protocol gradually turned into a JSON-oriented library of functions, leaving behind the SFS protocols (although some SFS concepts remained, such as room variables and user variables, in various forms).
The modern version of Infinity Protocol over WebSockets and TCP streaming is known as version Alef-Null, which is a fascinating maths concept that refers to a certain kind of Infinity.
There are 3 types of authentication supported for Infinity mode: Adult Sign-In, Child Sign-In, and Server-to-Server.
Before authenticating, a very limited vocabulary is available; see TOOTSVILLE INFINITY-PRE-LOGIN for a discussion of what is available to end users. Server-to-server connections send their authentication in advance.
Once authenticated, the vocabulary grows extensively. See TOOTSVILLE DEFINFINITY for an overview of Infinity Mode commands and how they can also be called as REST endpoints. Commands begin with INFINITY-, and can be found alphabetically in Definitions.
Note that some of these are deprecated or no longer useful, but all commands since 1.0 are still included in the vocabulary, including some which were originally Res Interactive proprietary extensions.
See Appendix 6 for an index of Infinity Mode commands.