Wednesday, September 29, 2010

Austin Java User's Group September 28th - Cassandra, MapReduce, and Roo

Forty people heard Jeremy Hanna present integrating Cassandra and MapReduce. My jumble of notes:
Cassandra, a horizontally scalable key-value database, was born at facebook.
It has no "master" node, just a bunch of peer databases.
Very fast for writting, fast for random reads, not good with ad hoc queries.
"Pig" is a scripting language used at yahoo that compiles down to MapReduce.
"Hive" used at Facebook is similar to "Pig", but more SQL like.

Ryan Stewart demoed Spring Roo, a scaffolding system that builds common code blocks like screens for create, edit, delete and data access functions for java; much like scaffolding pioneered by Ruby on Rails. I was very impressed by the intelligence built into Roo. My notes:
Roo accomplishes its magic by creating AspectJ files that are blended into the java objects. (C# has a more straight forward method with partial classes).
Roo is a process that runs in the background that can update its AspectJ files when it detects a change to a java object file.
Roo has a great help and guidence system.
Eclipse can be used to access Roo commands.

A few years ago our Java Users Group had demos of amazing code building tools shown by companies that charged thousands of dollars per seat for their software, now the amazing software is mostly free open source projects.

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