A Tale of Cross-Tab
Chapter 1: The Problem
In which our multi-tabbed hero is pushed into a problem.
One site, six connections
- Modern web apps push data
- Push requires a persistant connection
- Browsers limit the number of concurrent connections to the same protocol-domain-port combo
- So when the site is opened in multiple tabs at the same time…
Chapter 2: The Idea
In which our protaginist realises the world would be a nicer place if we all shared with one another.
Thinking like a native
A native app would have a single push connection, shared between the windows.
Browser windows only have direct references to each other if one was opened by another :(
We therefore need some kind of shared memory or event system to communicate
Chapter 3: The Solution
In which our communication issues are resolved, but our hero gets a nasty headache from a missing lock.
Shared between all windows
Even fires a
storage event when something changes
Pick a key, and use that to send (JSON-encoded) messages
Unlike within a page, you can get interleaved execution of JS between windows.
This makes synchronisation slightly harder: you can't guarantee ordering of events.