Abstracting backend

[TheYorkWei]

Features added:

• Abstract class backend with documentation
• Backend classes for myria, clang, grappa
• Separating out clang connection and clang catalog
• Moving myria multiway join as an option in drop down backend list
• Factoring out myriaconnection template variable to connection
• Make connection string, project site for backend dynamic
• Include dropdown list in queries page, change table dynamically
• Skipping query test on myria_up now that pages are loaded dynamically in js
• Clarify README in clang server to set up server and insert basic datasets
• Updating clang server to support the features above

[dhalperi]

This seems pretty neat! Shall we have another sit-down and talk about the code?

(Sorry for slow response -- I have been traveling).

[dhalperi]

ah.. I see this is not a merge into the master branch. Still would be willing to chat if it's useful!

[bmyerz]

It would be good to find a way to merge it into master, so we should chat. One way is to make it not change the frontend when the C/Grappa backend is not available in the deployment. This will let us merge the refactorings while avoiding confusing users of the Myria-demo.

[dhalperi]

I'm closing this for lack of activity.