Bundling is an approach to transferring files over a network that tries to combine the benefits of individual file downloading, Jar file downloading, and on-the-fly compression. The collection of files comprising the application is divided into groups, or bundles. Each bundle is then compressed cumulatively using either a general-purpose compression mechanism such as zlib, or a Java-specific archive format such as Pack.
As in individual file downloading, bundles are transferred in response to explicit client requests. Ideally, each bundle will consist entirely of files that are always loaded together. In addition, the files in the bundle should be ordered such that they match the order of requests by the client.
As in Jar file downloading, the bundles are precompressed, so no compression needs to be performed on the server at runtime. This allows the server to scale more easily to a large number of clients.
As in on-the-fly compression (and unlike Jar files), compression is performed on multiple files instead on individual files. This allows more opportunities to share redundant information between files, resulting in a better compression ratio than with individual compression.