Adding Additional Functionality and Enhancements to the Fetcher Module

A major goal for MDAnalysis 3.0 is the “support for streaming and cloud stor- age.”1. A natural extension of this object simply adding the ability to “fetch” more things for the internet. A typical molecular dynamics workflow involves using a shell script to programmatically retrieve online molecular dynamics ob- jects to save on disk, and then running an analysis script. This is rather inconvenient especially considering python strength as a “glue language.” While the user can always download an external library to perform the same functionality, the benefits of integrating downloaders or fetchers should be read- ily apparent. Integrating fetchers would provide a “batteries included” solution to this problem and such code would be inherently more readable and pythonic. Having code where every statement is readable and precise is one of the greatest strengths of Python compared to other languages. Rather than focusing on unfamiliar external libraries or nasty shell scripts, this approach would allow the user to focus on the impor- tant thing. The science! Thus, this proposal seeks to enhance the fetch module in three ways: live downloading of structures, live downloading of trajectories, and providing utilities to ensure file integrity.