Tag: REST

Building a content aggregation service with node.js

Fetching, aggregating and transforming data for delivery is a seemingly complex task. Imagine a service that serves aggregated search results from Twitter, Google and Bing where the response has to be tailored for mobile and web. One has to fetch data from different sources, parse and compose the results then transform them into the right markup for delivery to a specific client platform.
To cook this I’ll need:
– a web server
– a nice way to aggregate web service responses (pipelining would be nice)
– a component to transform the raw aggregated representation into a tailored client response.

I could take a stab at it and use Apache/Tomcat, Java (using Apache HttpClient 4.0), a servlet dispatcher (Spring WebMVC) and Velocity templating but it sounds too complex.

Enter Node.js. It’s an event-based web server built on Google’s V8 engine. It’s fast and it’s scalable and you develop on it using the familiar Javascript.
While Nodejs is still new, the community has built a rich ecosystem of extensions (modules) that greatly ease the pain of using it. If you’re unfamiliar with the technology, check-out the Hello World example, it should get you started.
Back to the task at hand, here are the modules I’ll need:
– Restler to get me data.
– async to allow parallelizing requests for effective data fetching.
– Haml-js for view generation

Continue reading “Building a content aggregation service with node.js”

Using Spring 3.0 MVC for RESTful web services (rebuttal)

Update Mar.04 Thanks to @ewolff some of the points described below are now official feature requests. One (SPR-6928) is actually scheduled in Spring 3.1 (cool!). I’ve updated the post and added all open tickets. Please vote!

This post is somewhat a response to InfoQ’s Comparison of Spring MVC and JAX-RS.
Recently I have completed a migration from a JAX-RS implementation of a web service to Spring 3.0 MVC annotation-based @Controllers. The aforementioned post on InfoQ was published a few days after my migration so I’m dumping below the list of problems I had, along with solutions.

Full list of issues:


Same relative paths in multiple @Controllers not supported
Consider two Controllers where I use a versioned URL and a web.xml file that uses two URL mappings:

@Controller
public class AdminController {
   @RequestMapping("/v1/{userId}")
   public SomeResponse showUserDetails(String userId) {
      ...
   }
}

@Controller
public class UserController {
   @RequestMapping("/v1/{userId}")
   public SomeOtherResponse showUserStreamtring userId) {
      ...
   }
}
In web.xml:
	<servlet-mapping>
	  <servlet-name>public-api</servlet-name>
	  <url-pattern>/public</url-pattern>
	</servlet-mapping>
	<servlet-mapping>
	  <servlet-name>admin-api</servlet-name>
	  <url-pattern>/admin</url-pattern>
	</servlet-mapping>

Continue reading “Using Spring 3.0 MVC for RESTful web services (rebuttal)”

Upgrading to Spring 3.0

In the spirit of beta I’m upgrading spincloud.com to Spring 3.0. I’m using version 2.5.6 currently but it’s missing REST support and I had to use Carbonfive’s REST library which worked like a charm. Now it’s time to get back under Spring’s fold and use their built-in REST support. Spring 3 opens the door to a lot of new features so I’m eager to try it.

I’m using Maven2 to get the jars and Ant to build the project. To fetch Spring 3.0 binaries, you have to add the following repository if you don’t have it:

<repository>
  <id>SpringSource Enterprise Bundle Repositorys</id>
  <url>http://repository.springsource.com/maven/bundles/milestone</url>
</repository>

and the spring packages that you need since the packaging has changed from 2.5.x. Instead of a single spring.jar file, now there is one per feature so you have to sort out what jars to include in the project. I ended up with the following:

  <properties>
      <spring.version>3.0.0.M2</spring.version>
  </properties>
  <dependencies>
   ...
  <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>org.springframework.core</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>org.springframework.web</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>org.springframework.transaction</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>org.springframework.orm</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>org.springframework.jdbc</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>org.springframework.web.servlet</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>org.springframework.context</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>org.springframework.aop</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>org.springframework.expression</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>org.springframework.test</artifactId>
      <version>${spring.version}</version>
    </dependency>
  </dependencies>

Once the jars are brought, I’ve replaced my old jarfiles with the all-new M2s then fired the build target.
The first issue I found was with the asm version.
Continue reading “Upgrading to Spring 3.0”

REST is DSL

I like RESTful URLs. They clearly express the intent of the provided resource. We humans speak a language close to REST when we talk to The Internet. 

Take a look at Google’s RESTful search query, probably the most used RESTful URL ever:

http://www.google.com/search?q=your-terms-of-choice

in freeform language this translates to: “Google, search for this term.”

How about the Flickr RESTful tag cluster search service:

http://api.flickr.com/services/rest/?method=flickr.tags.getClusters&
api_key=a6f11b67ae348a7b3f2da0d865b8bc1d&tag=Berlin

In Flickr lingo this means: “Fetch all tag clusters for the ‘Berlin’ tag”.

It doesn’t take much to understand RESTful URLs. They speak the language of the domain they represent and therefore in the Web Services provider-consumer world:

The collection of all RESTful services provided by a domain represents its web-oriented Domain Specific Language.  

DSLs have been around for a long time. For more information check Martin Fowler’s talk on the subject.