Tag: Java

Rest, Json, Spring and Maven

Rest, Json, Spring and Maven

This text is about developing RESTful web services using Java, Maven, Json and Spring 3. You can read instructions on how to setup a development environment for this kind of project here. The source code is available on GitHub.

Rest

As stated in this text,

[With Rest], requests and responses are built around the transfer of representations of resources. Resources are identified by global ID’s that typically use a uniform resource identifier (URI). Client applications use Http methods (such as GET, Post, PUT, or Delete) to manipulate the resource or collection of resources. Generally, a GET method is used to get or list the resource or collection of resources, Post is used to create, PUT is used to update or replace, and Delete is for removing the resource.

The Amazing Salume Application™

You work at a small business, a supplier company specialized in the finest salumes in the world, with a few clients, mostly bistros and restaurants (actually, there are only two clients, one bistro and one restaurant, but describing the company that way makes it looks larger). They both are good clients and the sales of the company is quite impressive. As the sales are expected to continue to grow, it is time to use a software application to aid the sale process. You decided to provide a RESTful web service to allow clients to manipulate their salumes orders through requests/responses in Json format.

Continue reading “Rest, Json, Spring and Maven” →

Implementing a Feature With TDD

A few days ago, I heard somebody ask “How do I start developing a functionality with TDD?” and I thought immediately that it would be a good idea to write about it.

A History

Suppose you are really popular, with thousands of friends in the Facebook, everybody in your neighborhood knows you and enjoys your company. In fact everyone in your city does.

Continue reading “Implementing a Feature With TDD” →

Developing an Interpreter to Math Expressions

Developing an Interpreter to Math Expressions
The support vote symbol redrawn in the SVG format.
Image via Wikipedia

We’ll start slowly, only dealing with the four binary basic operations: addition, subtraction, multiplication and division. Even though we defined a concise set of operations, I need to be even more humble in order to achieve our goals, and that’s why I’ll choose one of these operations to get started with the fun.

How about we begin with the addition operation? Sounds easy good to me. Doing that will lead the way to the remainder operations (I mean subtraction, multiplication and division operations). We can represent our math expression with a limited context-free grammar like this:

MathExp -> VariableExp | Constant | AddExp | '(' MathExp ')'
AddExp -> MathExp + MathExp
VariableExp -> a | b | ... | z
Constant -> 0 | 1 | ... | 9

Let’s write a test first (using JUnit 4): if an ordinary ‘a + b’ expression with ‘a = 2’ and ‘b = 4’ must be solved, one could think in the following API (specially if you read about the GoF Interpreter pattern):

Continue reading “Developing an Interpreter to Math Expressions” →