# HEAD
$ cat HEAD
ref: refs/heads/master

# master branch
$ cat refs/heads/master
f47f5c9f7c4fd8ab81a8285f07dd90796efd34f5

# commit object
$ tree 2fbccdcb39d49ddf6a9a76492575a457597f8433
parent 7dd3334c67ad1e6be1a9c7c8ca795f593f78ef9c
author John Doe <john.doe@yahoo.com> 1297434351 +0100
committer John Doe <john.doe@yahoo.com> 1297434415 +0100
bugfix (refs #123)

# tree object
$ git cat-file -p 2fbccdcb39d49ddf6a9a76492575a457597f8433
100644 blob f489719483633ec02e554bd23cf8616402a0e139	.gitignore
100644 blob fe398c7f4b31dd5d83e62567f17d1af343997428	MANIFEST.in
100644 blob a06e7371243eacab017a63026d8b7283095e795f	README
040000 tree b4039586f04ba4807d57af02d8da9390f177dc61	doc
100644 blob 20561c68d74669d7de55264b30fcd4132735a72a	setup.cfg
100755 blob bd391757f6cabd8d4aa6e5e5c8a1e7e7de762092	setup.py
040000 tree b701599a90608d46ed845453f1776caa935fc09c	src

[1] http://progit.org/book/ch9-3.html

• Consistency
• Availability
• Partition Tolerance

The CAP Theorem says that you can guarantee only one of the three. Most web-applications accept eventual consistency with the architectural approach BASE (Basically Available, Soft-state, Eventual consistency) [2], which is the logical opposite of ACID.

[1] Brewer’s CAP Theorem
[2] The Challenges of Latency

• Redis, In-Memory-DB: http://code.google.com/p/redis/
• Riak, written in Scala: https://wiki.basho.com/display/RIAK/Riak
• Cassandra, used at Digg, Facebook, Twitter: http://cassandra.apache.org/

[1] NoSQL-DB.org

Maybe the single most important productivity feature in Ringo is its auto-reloading module loader. It will pick up any changes as you code on a web applications without restarting. And while it is possible to disable reloading for deployment, it is so fast that you can usually leave it on if you want.

Another area we’ve put a lot of effort in is error reporting. In Ringo you will virtually always get file name and line number information as well as a full JavaScript stack trace with your errors. [...] In addition, you’ll get detailed descriptions of syntax errors and warnings for missing var declarations, which are hard to debug and can alter the behaviour of JavaScript code in bad ways.

Another major productivity boost is Ringo’s Java interoperability. Using the LiveConnect feature of the Rhino JavaScript engine gives you instant access to the gazillion of Java libraries out there. Just put it on your classpath and start using it. [2]

[1] RingoJS
[2] RingoJS Philosophy

A key feature of the Google Web Toolkit (GWT) is that it allows developers to write browser-hosted Web applications entirely in Java, and have GWT translate that Java code into browser-specific JavaScript. In this interview with Artima, Scott Blum, the Google software engineer behind GWT’s Java-to-JavaScript compiler, talks about the challenges of turning Java source code into JavaScript. [1]

[1] Compiling Java to JavaScript

In JavaScript, each Object can inherit properties from another object, called it’s prototype. When evaluating an expression to retrieve a property, JavaScript first looks to see if the property is defined directly in the object. If it is not, it then looks at the object’s prototype to see if the property is defined there. This continues up the prototype chain until reaching the root prototype. Each object is associated with a prototype which comes from the constructor function from which it is created. [1]

[1] Object Oriented Programming in JavaScript

Anyone who has studied or knows a second language knows that some things just don’t translate. The same applies to programming languages. Javascript has lots of features that Java doesn’t: first class functions, closures, extension methods, a vastly different “this” context, anonymous objects, dynamic typing and so on.
…
My position can be summed up as: GWT treats Javascript as a bug that needs to be solved.
…
The weaknesses and limitations of the end result are the combined weaknesses of both languages (or “A union B” in a maths context where A and B are the two languages);
…
GWT compiles are brutal, so much so that significant effort has gone into improving the experience with GWT 1.6+ and 2.0. Draft compiles, parallel compilation, optimized vs unoptimized Javascript and selected targeted browsers in development. These all can help but these are in part counteracted by increasing compile times with each version. [1]

[1] Lost in Translation or Why GWT Isn’t the Future of Web Development