Dojo includes several new modules which open up new querying and caching capabilities for Dojo data stores. dojox.data.ClientFilter is available in Dojo 1.2, and provides the ability to cache queries, update the query results and cached queries based on local modifications, and performs sub-queries and sorting on the client-side. The JsonQuery is a new mixin class for Dojo 1.3 that converts Dojo query objects and sort objects to JSONQuery expressions; JSONQuery can be used for delivering complex queries to the server. JsonQueryRestStore is a new module (for Dojo 1.3) that extends the JsonRestStore and combines the ClientFilter and JSONQuery such that any query can be executed on the client or the server automatically based on what data has been locally cached on the client-side, utilizing dojox.json.query to execute queries on the client-side when appropriate.
Dojo‘s improved RPC and new REST services can be used with a wide array of web services. One particular use is Amazon’s Simple Storage Service (S3). Dojo can connect to Amazon S3’s with a trivial proxy and be used as a normal RPC service. Not only that, Amazon S3 is a REST service and therefore it can be used as a data store with Dojo’s new REST implementation of dojo.data, JsonRestStore. You can read and write to your S3 database using the convenient Dojo Data API, and use the data store in Dojo widgets.
NOTE: This post is very out of date. For more up to date information about RESTful JSON in Dojo applications there are a number of more recent tutorials are available, such as the Dojo Store introduction, as well as tutorials demonstrating store-driven grids and trees, among others. You should also take a look at dstore, the next generation Dojo store architecture, for an even more modern take on RESTful JSON. We have a series of tutorials introducing the concepts.
Complex database driven widgets can be utilized with minimal coding effort. RESTful JSON is an increasingly popular database interface, and in later posts we will look at how JsonRestStore can be used with Amazon S3, CouchDB, Persevere, and Ruby on Rails. The JsonRestStore fully implements the Dojo Data read, write, notification, and identity interfaces. Therefore it can be used with any widget that can utilize these data stores including widgets with editing and live auto-updating features.