Summary

In this chapter, you learned about various design patterns for Ajax solutions. You first learned about how to use Predictive Fetch to improve the user experience through preloading information that is likely to be used in the future. You created an example using Predictive Fetch to preload pages in an article after a few seconds, when it is likely that the user intends to read the entire article.

Next, you learned about Submission Throttling, which is a way of incrementally sending data to the server instead of doing it all at once. You learned how to use this pattern for data validation in a form. It's sibling pattern, Periodic Refresh, was also discussed, which periodically receives information from the server. You built an example using Periodic Refresh that displays a notification when a new comment has been posted to a blog or message board.

This chapter also introduced you to the Multi-Stage Download pattern, which is a way of continuing to download extra information after the page has loaded. You learned that this would lead to faster initial download time for pages and that you can control the frequency and sequence of requests in any way you see fit.

The last section discussed fallback patterns that are used to handle errors in client-server communication. You learned that there are two types of errors you may encounter: server errors (such as 404 not found) or communication errors (where the server cannot be contacted). Two patterns, Cancel Pending Requests and Try Again, were discussed as ways of dealing with these errors.