Summary:
Ref T4324. Currently, an Aphlict client (with a corresponding connection to the Aphlict Server) is created for every tab that a user has open. This significantly affects the scalability of Aphlict as a service. Instead, we can use `LocalConnection` instances to coordinate the communication of multiple Aphlict clients to the server.
Similar functionality existed prior to D2704, but was removed as the author was not able to get this functionality working as intended. It seems that the main issue with the initial attempt was the use of the `setTimeout` function, which seemed to be a blocking call which prevented messages from being received. I have instead used an event-based model using a `Timer` object.
Roughly this works as follows:
# The first instance will create an `AphlictClient` and an `AphlictMaster`. The `AphlictClient` will register itself with the `AphlictMaster` and will consequently be notified of incoming messages.
# The `AphlictClient` is then responsible for pinging the `AphlictMaster` at regular intervals. If the client does not ping the master in a given period of time, the master will assume that the client is dead and will remove the client from the pool.
# Similarly, the `AphlictMaster` is required to respond to pings with a "pong" response. The pong response lets the clients know that the `AphlictMaster` is still alive. If the clients do not receive a pong in a given period of time, then the clients will attempt to spawn a new master.
Test Plan: I have tested this on our Phabricator install with a few tabs opened and inspecting the console output. I will upload a screencast of my test results.
Reviewers: #blessed_reviewers, epriestley
Reviewed By: #blessed_reviewers, epriestley
Subscribers: epriestley, Korvin
Maniphest Tasks: T4324
Differential Revision: https://secure.phabricator.com/D9327
Summary: Provide a reasonable JS API for the Aphlict client. Provide an example behavior to invoke it.
Test Plan:
Ran "aphlict_server.js" with:
$ sudo node aphlict_server.js
Loaded /aphlict/. Opened console. Got "hello" from the server every second.
Got reasonable errors with the server not present ("Security exception", but this is because it can't connect to port 843 to access the policy server).
Reviewers: ddfisher, keebuhm, allenjohnashton, btrahan
Reviewed By: btrahan
CC: aran, epriestley
Maniphest Tasks: T944
Differential Revision: https://secure.phabricator.com/D1800
Summary:
This is purely a prototype at the moment, but the basic functionality sort of
works.
I'm not sure how far I want to go with this but I think we might be able to get
somewhere without it being gross.
The idea here is to build a notification server WITHOUT using Comet, since Comet
is extremely difficult and complicated.
Instead, I use Flash on the client. LocalConnection allows flash instances to
talk to each other and connect() can be used as a locking primitive. This allows
all the instances to elect a master instance in a race-safe way. The master is
responsible for opening a single connnection to the server.
On the server, I use Node.js since PHP is pretty unsuitable for this task.
See Github Issue #3: https://github.com/facebook/phabricator/issues/3
One thing I need to figure out next is if I can reasonably do SSL/TSL over Flash
(it looks like I can, in theory, with the as3crypto library) or if the server
needs to just send down version information and trigger a separate Ajax call on
the client.
Test Plan:
Created a client pool and connected it to the server, with election and failover
apparently working correctly.
Reviewed By: aran
Reviewers: Girish, aran, jungejason, tuomaspelkonen, davidrecordon
Commenters: Girish, davidrecordon
CC: aran, epriestley, Girish, davidrecordon
Differential Revision: 284
