RESTing easy with Groovy’s HTTPBuilder

Interacting with RESTful web services couldn’t be easier with Groovy’s HTTPBuilder. This handy library has a slick extension dubbed RESTClient, which facilitates handling all aspects of REST (such as GET and POST) quite nicely; plus, parsing and building of both requests and responses in either JSON or XML is a breeze, baby!

Check it out– first, you must create an instance of RESTClient like so:

def zorillo = new RESTClient("<a href="https://acme.zorrillo.com/">https://acme.zorrillo.com/</a>")

Because it’s my bag, I’m interacting with a service whose base URI is acme.zorrillo.com. With this instance, I can easily obtain information via an HTTP GET like so:

def res = zorillo.get(path:"widget/1010081127")

In the above code, I’ve issued a GET request to <a href="https://acme.zorrillo.com/widget/1010081127">https://acme.zorrillo.com/widget/1010081127</a>, which returns an XML response that looks something like this:

<pre class="prettyprint"><code><widget id='1010081127'>
 <type>JPM</type>
</widget>

Interestingly, with an instance of a response (in my case, res), you can grab an instance of the returned XML via the data property, which is the root node returned via Groovy’s hip <a href="<a href="https://www.ibm.com/developerworks/java/library/j-pg05199/index.html">https://www.ibm.com/developerworks/java/library/j-pg05199/index.html</a>">XMLSlurper</a>. Thus, data points to the widget element; consequently, I can grab the attribute id and the corresponding element’s value quite easily:

<pre class="prettyprint"><code>assert <a href="mailto:res.data.@id.text">res.data.@id.text</a>() == '1010081127'
assert res.data.type.text() == 'JPM'

Need to post some data? That couldn’t be easier either, man — simply use RESTClient’s post method, which allows you to use a MarkupBuilder to construct corresponding XML like so:

<pre class="prettyprint"><code>def ans = zorillo.post(path:"widget/",
		requestContentType: XML,
         body: {
           widget(id:'129033'){
             type("TFR")
          }
        })

Note in this case, the POST URL is <a href="https://acme.zorrillo.com/widget/">https://acme.zorrillo.com/widget/</a> and I’m posting a document which looks like so:

<pre class="prettyprint"><code><widget id='129033'>
 <type>TFR</type>
</widget>

But, because I’m using Groovy’s MarkupBuilder I don’t have to deal with XML directly — not bad, eh? The /widget service returns an XML document of the created widget if everything works; thus, I can verify things are kosher like so:

<pre class="prettyprint"><code>assert ans.status == 200
assert <a href="mailto:ans.data.@id.text">ans.data.@id.text</a>() == '129033'
assert ans.data.type.text() == 'TFR'

How’s that for easy, man? The next time you need to interact with a RESTful web service, consider using Groovy’s HTTPBuilder — it’s a snap!