So far we have been working with local data and hard-coding our information to create a store of records. But in real world applications we have our data in a database or maybe we get the information using web services.
Ext JS uses proxies to send and retrieve the data to the source. We can use one of the available proxies to configure our store or model.
A proxy uses a reader to decode the received data and a writer to encode the data to the correct format and send it to the source. We have three available readers to encode and decode our data: the Array, JSON, and XML readers. But we have only two writers available, only for JSON and XML.
There are seven types of proxies at our disposal. If we want to change our source of data, we should only change the type of proxy and everything should be fine. For example, we may define an Ajax proxy for our store or model and then we can change it for a local storage proxy.