How to Implement a Class/Database Listener?

Question

I am using the Parse.com database service for a PhoneGap app we are creating. We have users that can mark themselves (First User) "Available" for their friends (Second User), and I need a way to listen for that toggle in availability on the second user's side, so their friends list can update without having the refresh the page.

With Parse, your interaction with the database is monitored by # API calls and Burst Limit (Number of API calls per second) so I need to only call the database for the change in status when it is actually changed, I can't keep a setInterval on otherwise it will make the burst limit too small for other user, or it will cause to many API calls for no reason if the status isn't changing.

How can I got about this?

inf3rno · Accepted Answer · 2014-03-01 21:08:27Z

1

You should try socket.io with intercom.js. The first one does the pushing to the client, the second one ensures that only a single socket is open by multiple tabs. Socket.io has multiple fallbacks on client side, it can use websockets, flash, maybe even long-polling I guess...

The server side should support sockets. By nodejs it is very easy. By classical http languages, for example php+apache just the long-polling will work I think.

Be aware that your data pushing application will be socket based and not request-response based, so it won't be part of you webservice. Probably you should only push, that the user list must be refreshed. So there won't be any duplicated code...

answered Mar 1, 2014 at 21:08

inf3rno

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12 Comments

Cow Over a year ago

I'll take a look at this, I'll accept your answer in a bit if nothing else comes in. I appreciate it.

Cow Over a year ago

Looks like we are going to have to change to a service like Pubnub with real time capabilities... thanks!

inf3rno Over a year ago

Not necessarily. You can run 2 services, one for socket connection and one with a REST or webservice interface. So you don't have to drop your existing code, just write a simple socket api based on database triggers for example...

inf3rno Over a year ago

Are you sure that this small feature does worth the effort?

Cow Over a year ago

inf3rno, for the small feature I wanted to implement right now, no. But for our big feature, yes. GPS has to update constantly, and this will help.

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