Move all functions and classes currently available through lib/name and
libName to be under a single flat namespace in lib. This make
reorganising the lib namespace much simpler as the location of symbols
can move without breaking the consumers of lib.
The multi-entrypoint design was already problematic for the web plugin
system which couldn't effectively use it due to how webpack's shared
module system is awkward to set up with multiple entrypoints per package.
Format arguments to have nested structures start on a new line instead
of inline to make it easier to see where the structures starts and what
structure it is.
Validate messages received on the controller from hosts and control
nodes before handling or forwarding them. This should prevent
performing actions that are not allowed by the role system and block
simple attacks such as spoofing the source address of a message.
Split up the action of registring an event or request data class to be
decoded by the Link class and the action of registring a handler for
those requests and events. This moves the validation work from Link
instantiation time to startup initialisation which makes logic errors
fail on startup instead of failing instantiation of the link when a
connection attempt is made.
Additionally implement a partial validation logic for messages received
using the newly refactored message registration. This unfortunately
ended up merged with the registration refactor.
Reverse the direction of the API for sending messages from
messageDefinition.send(link, { content });
to
link.send(new MessageClass(content));
and convert all message definitions to use the JSON serialisable class
pattern and explicit registration of message handlers, along with a
end-to-end based routing of messages instead of link to link.
The experience I gained from the existing way messages were defined and
sent over links was that it was difficult to understand for people
unfamiliar with the system. The automatic registration of message
handlers ment that code was being called as if by magic from nowhere
with no easy way to discover it. The manual forwarding and rules for
what can be sent where and how obscured its working.
The use of pure JSON as both input and output from message handlers made
it tedious to work with. Data had to be manually converted between the
program representation and the over the wire format, which made handler
code unplesant to write. Particularly because the over the wire format
used snake_case while the program code uses camelCase for variables.
The idea behind the decision to do it this way was to make it more clear
which data came from the wire and which from the program, and while this
worked it didn't make message handlers any nicer to write.
The direction of the API and magic registration of message handlers also
meant that a future migration to TypeScript would be troublesome. While
it may be possible to implement, the degree of TypeScript magic required
would go starkly against the principle of keep it simple stupid.
By refactoring to using the JSON serialisable class pattern most of
these issues go away. There is no longer a need to distinguish the on
wire format of messages with the program representation because the only
place that deals with the wire format of messages are the toJSON and
fromJSON methods on the classes themselves. Message handlers will work
with proper instances of classes instead of raw data, something that
makes them easier to write, and trivial to type with TypeScript.
End-to-end routing also simplifies sending messages that need to do
mulitple hops to reach the destination. And removes the need for having
all messages be specified in plugin's info module, as they can be routed
without having to be parsed completely.
The explicit registration of message handlers is something that I
thought would be tedious boilerplate code that could be automated away.
But experience now shows it to be the opposite. Allthough dull
repetition, the purpose it serves is to link together the code in a way
that humans can easily find. With explicit registration searching the
name of the message handler in the editor will show the registration that
ties it together with the type of message it handles and the kind of
registration. With implicit registration searching the name of the
message handler turns up only the handler with no clue as to what calls
it.
Use lib* prefix for the modules impored from the lib package to help
distinguish them more from ordinary variables. Fix up the naming
convention for files to be consistently lowercase_underscore for
JavaScript files.
Split up codebase into the packages @clsterio/lib, @clusterio/master,
@clusterio/slave, and @clusterio/ctl using lerna to manage them. This
will allow deployment to use only the parts needed reducing install
size, and better separate the code into shared library, master, slave
and control.
Remove connection and client subclasses of Link and put the connection
logic into a "connector" class. The connector deals with sending
and receiving messages, handling the connection and reconnection of lost
connections and giving sequence numbers to messages.
This move the logic of the actual connection away from the link
sub-classes, which in turn means the connection should be a lot easier
to mock in tests.
Rework client.js to support running multiple instances at once and be
managed remotely and implement the neccessary communication
infrastructure for this.
Due to circular dependencies on the implementation of this the master
branch is significantly broken after this.
Hornwitser