#69 CQPweb: run corpus install without requiring browser connection to be maintained

[Andrew Hardie]

Suggested by Mike Lynch on the CWB list:

"Our university's firewall cuts off web connections after around 20 seconds, which means that indexing and installing corpora over a certain size via the admin interface gets interrupted.

The workaround for this so far has been to index and add metadata using command-line tools on the server, but I'd like to get installation working via the web interface."

AH: it would be good to move away from having the server/browser connection maintained throughout indexing. (Basically to make the process disconnect the browser once indexing starts). I'll add this as a feature request. However, it's a big re-engineering of the UI so it won't happen soon.

Implementation notes:

• standardise action buttons/forms/links to a single UI element controlled by templating class (UIButton / UIActionControl (?))
• have three modes of action:
  go (browser go to address),
  async (httprequest in javascript, UI waits for response then updates),
  ** poll (httprequest in javascript, UI gets response that action has started, another UI location can then poll the server to find out when it's finished).

Move all actions gradually to use this standardised UI class to minimise code duplication.