Data Pull vs. Push OOP Approach

Question

When I design my system from scratch, I often face a dilemma whether my object should push information into another objects OR whether the objects should

Answer 1

Usually 'pulling data' means you're doing an ajax call and running a callback upon its successful response. This isn't bad, but it can be overly intensive if you're checking for data updates and are thus doing it on an interval.

But in the context of an online web application, an alternative to this is push with long polling. Since long polling isn't terribly different from the first method, I propose you do the following:

Create a long polling method that pulls data from a a semi public push url endpoint (aka a webservice for pubsub), and then update everything that needs to be updated via using a publisher-subscriber design pattern in your client. That way your updates are more decoupled from the data source.

Here's a white paper that was written on this topic by IBM. http://www.ibm.com/developerworks/library/specification/ws-pubsub/