Tag Archives: Javascript

{jaggery.js}

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Is something I’ve been working on at wso2 for sometime, if you are following me I have tweeted the updates, releases etc. Jaggery went live with its fifth milestone, few weeks ago at jaggeryjs.org, its still young and has alot to improve.

Explaining a little bit about jaggery; Its NOT an alternative to node, its simply a toolkit to easily compose webapps and apis. Its a completely javascript way of writing all parts of the web application, and communicate throughout in json. Jaggery has out of the box features to create RESTfull applications, and its one of it’s value propositions. Jaggery can be easily extended via modules which can be written in javascript or java for that matter.

A very simple page that prints out some request properties in jaggery looks like,

<html>
   <body>
      <p>
      <%
          print("Method : " + request.getMethod() + "<br/>");
          print("Protocol : " + request.getProtocol() + "<br/>");
          print("User-Agent : " + request.getHeader("User-Agent"));
      %>
      </p>
   </body>
</html>

Jaggery docs site also provide a tool for you to try out some code and play around. So you can simply copy the above code and paste in jaggery try-it

I recently did a webinar on jaggery that explains the simple case, over looking its API and samples. Below is the recording hope it’ll help.

Web Scraping & Parsing HTML to XML in Javascript

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Today I was working on a customer POC and happened to create few Google gadgets to visualize selected data sets from *.gov.uk sites. The scenario which is implemented was, mixed with inter-gadget communication and content search over data.gov.uk sites. I created three simple gadgets which communicates with each other, and one acted as the controlling gadget which pushed the search parameters to other two gadgets. The two content gadgets showed UK (1) primary school information and (2) electoral information. The pushed parameter was the postal code of different parts of UK. The direct.gov.uk has a form based implementation of this.

The Requirements for the POC was, simple and we already had working samples of such a scenario at WSO2 library.

  1. Show how one gadget can pass the context to other gadgets
  2. How gadgets can harvest data in various formats (in my previous post I explained on how to get data from RDF endpoints, which are also available in *.gov.uk sites)

The building blocks for the implementation was the search url, which was quite straight forward. for all the requests based on postal codes the direct.gov site served in the same manner (because of this important fact, the automation process became trivial). for an instance the url for primary school information retrial was,

http://local.direct.gov.uk/LDGRedirect/LocationSearch.do?LGSL=13&searchtype=1&LGIL=8&Style=&formsub=t&text=SE1+7DU

Where the param “text” changed according to the postal code. So far everything seemed straight forward, however at implementation, while using Gadgets API for content retrial, I faced problems in parsing text with javascript. Hence the gadgets.io.makeRequest supported HTML as text and the API method returned the retrieved HTML document as string making it quite impossible to process.

With some thinking and advise, I brought the Mashup Server in to the picture and used it to retrieve the data from the gov site and returned the result in XML format. Using the Mashup Server web scraping seems to be a piece of cake, We created a simple mashup using the scraper host-object and captured the result set in the search result page. The mashup code as follows,

function search(searchUrl) {
	var scraper = new Scraper(
		
		    {searchUrl}
			
			    
				
				   
				
			     
			
		
	);
	return new XMLList(scraper.response);
}

And finally the two gadgets were making service calls to the mashup service and retrieved the data as an XML object, making the data processing painless. The final version at the Gadget Server looked quite appealing.

WSO2 Gadget Server with UK gov data

Gadget Server look - in the end

Special thanks goes to Ruchira for helping me out with the mashup service :) You can download the Gadget code and the Mashup service and try the scenario yourself.