Read this before kick·off Sass

What is Sass?

Sass can be claimed as a most powerful CSS Extension language. It adds abundance of nice features to CSS, and helps the developers to build better stylesheets.

Sass is a CSS Preprocessor, How?

The developer writes Sass code in a .sass or .scss file and the Sass Preprocessor converts it to CSS format, that is .css file so that the browser understands the code and renders the page. The .scss format is the widely used one, because of its close to CSS syntax.

The advantage of Sass over css is that, it eradicates the monotonous code style of CSS and craft CSS easily.

How to install Sass on Windows?

Sass is a package provided by the programming language Ruby as one of its dependencies. All the packages of Ruby are called as Gems. Sass is one such Gem. To start with we need to install Ruby first on our machine.

Download and install the proper version of Ruby Installer that suits your computer from the below link.

http://rubyinstaller.org/downloads/

Please note that for a 64 bit Windows operating system, the below link works charm.

https://github.com/oneclick/rubyinstaller2/releases/download/rubyinstaller-2.5.0-2/rubyinstaller-2.5.0-2-x64.exe

 

Start using Sass

 

In your computer create a dummy folder to test, with couple of subfolders named, CSS and SCSS, and a .scss test file in the scss folder as below.

 

Now you can watch your .scss test file for any changes and tell the preprocessor to convert to .css file using an inbuilt watch program. 

In order to do this go to the Dummy folder in the command prompt and run the below command.

sass --watch scss:css

Hereupon when you do any change in your .scss file, the watcher detects the change and compile it into a .css file. Try adding code to .scss file, save and check for the compilation happening automatically.

Outline of Rest Architecture for Web Application

Rest (Representational State Transfer) is an architectural style for the web application.
A restful web service is nothing but a service that follows the below six important constraints that defines a rest architecture.

Client Server Separation

The Client and Server has individual responsibilities to do. The client's involvement is not needed for the server to perform any of its task and vice versa. So they are independently serviceable .

Stateless Communication between client and server

The client sends any request to the server with all the information embedded within the request itself
and the server provides the response based on the request and no state is maintained i.e no other information is retained by either the client or the server.

Cache-able

The response from server should indicate to the server if the information is cache able or not. This way the client can use the cached data and need not request the server for repetitive data.

Code on demand

The Server can optionally send piece of code to the client, where it can be executed in order to extend the functionality of the Client.

Layered System

The Rest based system can have multiple layers in it, including the client and many layers of server.
But each layer has knowledge as well as interaction only with the adjacent layers.

Uniform Interface

Interface separates from implementation and this is accomplished with the below four sub constraints of any rest architecture.

Resource Identification

The action of sending requests and receiving responses done by the client acts as an interface for the restful architecture. The request to get any resource is identified by the URI and the response is always received in any of the formats like HTML, JSON and XML. This doesn't have any dependency on how the data is stored or manipulated on the server side, which is considered as the implementation from server end. In this way, this constraint allows to achieve the Uniform interface constraint.

Operation control of resources by client

The client can perform any change to the resources on the server with the help of the HTTP methods and URI.

Independent messages

Any request sent by the client doesn't have any dependency on any other requests generated by the client. Each request is complete on its own to get the necessary response from the server.

HATEOAS (Hypermedia as the engine of application state)

This constraint provides a paradigm that whenever a client sends a request to the server, the server should provide not only the requested information, but all the possible related end points in the form of links to the client.

Outline of HTML 5 Semantic Structure

HTML5 has new semantic tags replacing the old conventional tags. The new semantic tags describe the content in a better way than the traditional ones with numerous advantages. Here is the pictorial representation of the major HTML5 structural tags.

HTML5 semantic elements are supported on all contemporary browsers like Chrome, Firefox, Safari etc. Let's have a look on the usage of important semantic tags.

<article>(Block) - Content such as blog post or Article.

<aside>(Block) - Content slightly related to the main content on page i.e the secondary content.

<figure>(Block) - Grouping static content like image/Video etc

<figcaption>(Text) - Use with <figure> tag to provide caption.

<footer>(Block) - Provide author information, Copyright data etc.

<header>(Block) - Include Navigation and introductory headings, logos.

<hgroup>(Block) - For grouping <H1> to <H6>

<nav>(Block) - Site level Navigation.

<mark>(Text) - To highlight or reference text.

<section>(Block) - Grouping of content with common headings (similar to chapters).

<time>(Text) - For Date/Time representation.

What are the main advantages of new semantic tags?

1. Maintenance of HTML page is easy as the new markups have extra information about the structure within their name itself.
2. Better Search Engine Optimization.

Comprehend the difference between Block and Inline Elements of HTML

There are three major types of HTML elements.

1. Structural Elements
2. Block Elements
3. Inline Elements

Structural Elements

The Structural Elements are <html>, <head> and <body> tags.

Block Level Elements

1. All Block elements occupy a rectangular space within the web page and the content before and after the element are separated with the help of line spacing (in other words line break) i.e they represent a separate section from the elements preceding and following them.
2. The block elements provide structure to a particular web page. 
3. Examples of Block Elements: Headings, Paragraphs, Body, <table>, <div> etc.
4. HTML5 introduced new block elements for every sections of the web page like section, header, footer etc.
5. A Block element should never be inside an inline element.
6. Many of the block elements can be nested. A block element can contain other block elements. But the exceptions are <p> and <pre> and they can contain only inline elements and plain text.
7. They never overlap or overlapped by other elements.
8. They change the content flow.
9. Block elements occupy the full width available and just enough height to accommodate the content.
10. They have the CSS box properties.

Inline Elements

1. They are the elements within a line. Examples: <span>, <em>, <img>, <a> etc.
2. Inline elements can contain inline elements but no block elements.
3. Inline Elements are mostly used to format words and characters.
4. Inline elements take only as much space as their content requires.
5. They do not change the content flow.

The below HTML and Image differentiates between block and inline elements.

<h1>Block Level Element - Heading</h1>

<p>Block Level Element - Paragraph1

<span>Inline Span Element</span>
<a href="">Inline Anchor Element</a>
</p>
<p>Block Level Element - Paragraph2</p>

 

The Java program doorway - main method

In any Java Application, there should be at-least one main method available and can be in any of the classes. The JVM starts the execution from the first statement of the main method and ends after the last statement. A Sample main method...

public class MyFirstApp

{

public static void main(String[] args)

{

System.out.println("Main method inside class MyFirstApp");

}

}

The keyword 'public' specifies that the main method can be accessed from anywhere. 

The 'static' keyword implies that the main method can be accessed without instantiation i.e objects are not needed to access the main method.

'void' denotes that the main method doesn't return any value.  

String[] is an array of strings (sequence of characters) and is named 'args' (This name "args" can vary"). In Java, the main method needs a single array of strings as parameter.

Queries:

Can we declare a main method as Private?

                               or

Can we remove static keyword from the main method?

                               or

Can we remove the argument String[] args from the main method?

If we do any of the above, the compiler will run properly. But at run time, the JVM throws the error message.

What will happen if I write "static public void" in place of "public static void"?

The program will run and execute properly with no errors.

Can I have many main methods in the same class?

No, Compiler error occurs.

Note:

The name of the class containing the main method must be the same as the name given to the program file itself.