четвер, 7 лютого 2013 р.

Resolving underscore templates and Java JSTL conflict

Front-end development has made a huge step for the last couple of year... Could you imagine backbone or underscore in earlier 2010? I'm not... now it has a lot of new possibilities, and new changeless for JSTL users.

Today you can create real cool application with using Rest and html/javascript. So, you can (and you have to) separate backend and frontend development. As for me, the real cool thing is a templating engine in javascript. I'm talking about frameworks like underscore.js and mustache.js. Both is awesome, both is cool and must to be used. In this article I'll discuss underscore templatting.

Let's imagine you consider use underscore and read about templates. The Underscore toolkit includes an easy-to-use templating feature that easily integrates with any JSON data source. For example, you need to repeat some fragment of html many times. For Example, you get list of employees in your AJAX request. With template you have to define place for inserting list of users (let's we want to have table).

Your restfull service returns json with name, position and set of phone numbers, you fetch it w/ backbone and create related DOM.

However there is one problem. In JSTL <% %> is using to mark scriplets... So, we have conflict: JSP vs underscore. And JSP wins!  Fortunately, there is solution - you can override underscore template symbols to use <@ @> instead of <% %> for underscore!

    // underscore templating
    $(document).ready(function ()
     _.templateSettings = {
      interpolate: /\<\@\=(.+?)\@\>/gim,
      evaluate: /\<\@(.+?)\@\>/gim,
      escape: /\<\@\-(.+?)\@\>/gim

So, html fragment:
<table id="employees">

We aim to insert list of employees here with the next information: employee's name, position, phone number(s). Ok, it's really easy. Our template is:
<script id="employee-template" type="text/template">

  <@ _.each(phones, function(i) {<@=i@>, }@>

Template is ready, know just let's init this template:

var template_html = _.template($('#employee-template').html());
var h = $(template_html({name: item.get("name"), position: item.get("position"), phones: item.get("phones")}))

$('#employees').append( h );

that's all!

середа, 6 лютого 2013 р.

Working with MongoDB using Kundera

When we are talking about JPA2 we usualy imaging relation database and one of ORM (Hibernate or EclipseLink). However, JPA is general approach not only for relation system. It covers NoSQL as well. And one of wonderful JPA implementation oriented on non-relation databases is Kundera.

Initially Kundera was developed for Cassandra. It seems to be a good idea, if you don't use relation you don't have the main problem of different ORM frameworks:) HBase was the next database supported by Kundera, and now is the time for MongoDB

Also, support for relation schema was anonced! Awesome! Be honest, I don't believe the it'll work well. Otherwise we'll get power competitor to Hibernate and K.
But, Kundera is awesome one to creating prototype, when you need base CRUD operations and just to want to try you application with Cassandra, HBase or MongoDB. The beautiful parts is possibility to write JPQL queries instead of native database structures.

Let's figure out how we can use Kundera with MongoDb... Mongo JPA