I am new to Asp.net and i saw many tutorials talking about css and Html and Xml Style sheet so please can anyone tell me what is the difference between those 3 Languages and what they are used for ? Also i want to know if we need to know HTML since when i was training on visual studio i saw that it is automatically generated when we add a control from the tool box . Thc for any help .
HTML is a markup language for describing the semantics and structure of documents.
CSS is a language for describing how to present documents written in markup languages.
XSL is a collection of specifications for presenting and manipulating documents written in markup languages.
[Do] we need to know HTML since when i was training on visual studio i saw that it is automatically generated when we add a control from the tool box
Yes. Visual Studio generates pretty poor markup.
The WikiPedia pages for HTML, XML and CSS will have a ton of information, as well as links to a ton more information. So I'll just address the second part of the question...
If you're doing web development, it's definitely in your best interests to learn these things, especially HTML. Sure, Visual Studio will generate stuff for you and all you have to do is drag and drop widgets onto a form. However, if you don't actually know what it's doing for you or understand how the tool works then you're seriously limiting yourself.
Sometimes dragging an ASP .NET server control onto the form and setting a few properties is the best (as in quickest and easiest without significant side-effects) way to accomplish a particular task, sometimes it isn't. If you're familiar with only one tool then you can only do what that one tool is designed to do. You'll end up trying to fit other tasks into the scope of that tool, with potentially dismal results.
Visual Studio has a history of generating poor HTML. It's certainly improved over the years, but it's not something on which you want to rely. You can create simpler, more efficient, and ultimately easier to support code by having a better understanding of the underlying technologies involved and putting in a little work yourself.
I think you did not search for these:
HTML - Tutorial
HTML, which stands for HyperText
Markup Language, is the predominant
markup language for web pages. A
markup language is a set of markup
tags, and HTML uses markup tags to
describe web pages. HTML is written in
the form of HTML elements consisting
of "tags" surrounded by angle brackets
(like ) within the web page
content. HTML tags normally come in
pairs like and . The first tag
in a pair is the start tag, the second
tag is the end tag (they are also
called opening tags and closing tags).
Example:
<html>
<body>
<h1>My First Heading</h1>
<p>My first paragraph.</p>
</body>
</html>
Cascading Style Sheets - Tutorial
Cascading Style Sheets (CSS) is a
style sheet language used to describe
the presentation semantics (the look
and formatting) of a document written
in a markup language. Its most common
application is to style web pages
written in HTML and XHTML, but the
language can also be applied to any
kind of XML document, including SVG
and XUL.
Example:
<style type="text/css">
body {color:red;}
h1 {color:#00ff00;}
p.ex {color:rgb(0,0,255);}
</style>
XML - Tutorial
Extensible Markup Language (XML) is a
set of rules for encoding documents in
machine-readable form. It is defined
in the XML 1.0 Specification
produced by the W3C, and several other
related specifications, all gratis
open standards.
Example:
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
Related
I am working on HTML5 and i came across various HTML5 semantic tags like <article> <section> <aside> <nav> <header> <footer> <audio> <video> <source> <track> <embed> <canvas> etc.
I would like to what exactly is the advantage of using these semantic tags. is it for fast loading or any other feature?
Please share your thoughts.
It's to accurately describe the content of the tag.
For example this means when Google (or any search bot) crawls a page, it can more accurately dissect it and assign relevance scores to the various bits of content.
Wikipedia has a nice simple definition:
Semantic HTML is the use of HTML markup to reinforce the semantics, or meaning, of the information in webpages rather than merely to define its presentation or look. Semantic HTML is processed by regular web browsers as well as by many other user agents. CSS is used to suggest its presentation to human users.
So whether a browser takes special action upon tags like audio and video is purely up to the developer of the browser rendering engine, but they are there to be used.
Advantages of semantic tags
It's easier for computers to understand what content is in your document and how it is structured. For example, having article tags would make it easier for a tool like Safari Reader or Readability to find the content of a blog post.
Screen readers will also have more information about what is on the page. This is incredibly useful for vision impaired users, especially since they can more easily jump to navigation controls and article contents while skipping less important content.
It's easier for developers to logically sort out parts of HTML documents, and easier to semantically add CSS styles around your HTML.
Maybe this is a stupid question, but what is the difference between XSL and CSS? They are both styling sheets. When would you want to use one over the other. I looked around and saw that CSS is generally used before XSL when possible... but why?
XSL is used to refer to a family of languages used to transform and render XML documents.
CSS is a style sheet language used for describing the presentation semantics (the look and formatting) of a document written in a markup language.
Hence XSL and CSS are not the same and not interchangeable. While XSL languages are used to impact the structure of XML documents (i.e. the arrangement of the tags) CSS is used to impact the visual formatting of those tags.
Edit: There are no stupid questions, just badly researched ones ;)
Assuming you are talking about XSLT rather than "XSL" (the latter term should be avoided because it is used in different ways by different people):
CSS provides a great deal of capability for rendering content. This capability is increasing all the time.
XSLT focuses on transforming content.
For example, you can write a report that groups, sorts, and summarizes data in XSLT, but you can't do so in CSS. Until recently CSS couldn't alter the content in any way, for example by rendering <cite>3</cite> as [3].
You should use XSLT and CSS together. Use CSS for the pure rendering parts of the job, and XSLT for the transformation parts.
With the availability of Saxon-CE in the browser, you can also start to use XSLT for handling user interaction, such as responding to clicks by showing or hiding data: the kind of things you would otherwise have to do in Javascript.
It has been suggested that I use CSS for displaying XML. I know in my heart that this is wrong, but cannot find the words to adequately convince others. Can anyone provide me with a list of pros/cons of using CSS and XSLT for displaying XML.
Thanks!
What your heart tells you is correct. Though it is possible to use CSS for XML, XML itself does not have any semantics. CSS is meant for the web, for HTML and for giving semantic data a (good) look.
XML is way more general then that. XSLT is was invented for transforming one data format to another (XSLT 1.0 only XML, XSLT 2.0 any Unicode data format), i.e., XML to HTML or XML to XSL-FO or another XML or text format. XSL-FO was invented for laying out XML on paper or screen and is much more detailed then CSS.
Some pros and cons on CSS+XML
Mainly cons, esp. in the light of using XML in a browser. Skip to the overall advice below if you don't want all my babbling ;-)
CSS cons 1: no CSS+XML for internet
The cons: it depends a lot on the context, but if you want to use XML for display on the internet, think again: don't use XML, but transform it into HTML. Then use CSS + HTML to display your data. If you use XML on the internet, no search engine or crawler, will understand the difference between <x> and <y>, but they will understand the difference between <h1> and <h2>.
This alone is enough a reason for using XSLT to transform to HTML + CSS and avoid XML on its own.
CSS cons 2: CSS means lots more work
The other extremely big reason you can use: XML + CSS means defining each and every element in CSS. Using HTML + CSS means user agents already know the default layout properties for all elements. Using XML + XSLT means usually you create HTML + CSS. You should do this on server side, because client side XSLT is not very reliable and cross-browser compatible still.
CSS cons 3: accessibility
(sorry, I can't find pros) Unless XML has semantics (SVG, as mentioned by another user), it makes little sense to use CSS for layout. If the layout is supposed to be semantically understood by a user agent, XML + CSS is a no-go. Text-to-speech readers have no idea what to do, WAI (accessibility) validity will be impossible etc.
CSS cons 4: maintainability, understandability, scripting, trouble
Using XML makes it hard to do any client side scripting (yes, the DOM is available, but how do you tell the browser what the script-tag is? But perhaps it'll react to <script>, but hey, you need XSLT to get that tag in there) and makes it hard to make it cross-browser correct (some browsers have a hard time using XML per se). Anything HTML (like meta, title, body, script) will not be available. There's no way to add title attributes or to tell the browser what an image is (afaik).
No script in existence will work on you XML-only page (prototype.js? jquery.js? ajax? no no and no).
Anybody looking at your code will have to learn what each tag "means". Using XSLT to transform to HTML, prevents this. This extra step is beneficial and should be applied whenever you go from XML to browser display.
CSS pros 1: domain specific
If your domain is SVG, SMIL, OD or anything else, you probably already know this: CSS is an integral part of the specification and should be used. This is completely different from pure, possibly unstructured, data XML.
AJAX thought
Just for comparison: any asynchronous AJAX call (should) return XML. But any library working with it, will either interpret it as HTML, or will use XSLT or another means to transform it prior to injecting it in an existing page.
Overall advice
Based on the remark from the OP, we are looking at data XML (not SVG or OpenDocument) and it needs to be displayed in browsers. Accessibility and indexability are not important. But that doesn't really matter: you shouldn't use XML + CSS alone, unless you're really into some adventure and want to find out all the shortcomings of XML in browsers, want to invent every HTML tag again and define each and everything, only to give up after a while and revert to HTML (XML + XSLT == HTML + CSS).
Update: added cons 2
Update: added cons 3 and pros 1
Update: added cons 4, AJAX note and a conclusion
CSS:
Styling and overall visual presentation
XSLT:
Styling and visual presentation (if desired)
Allows complete and radical changes of the actual tree that's rendered
If your XML maps pretty nicely to individual layout elements then use CSS, if you need more work in adapting it for display, then use XSLT. Things like arbitrary re-orderings of content or collapsing multiple lists of values into a table, etc. don't lend themselves well to CSS. CSS really only works nicely if your overall structure of the document is already the same you want to display.
CSS seems to fail for XML in IE8: How to apply CSS to namespace prefixed elements in IE8?
There is nothing inherently wrong with using CSS to style XML, it's just not done very often (although I've done it in the past as an experiment).
Take SVG as an example: it's XML, and it can be styled with CSS. Also, have a look at section 3.1, "Definitions", of CSS 2.1:
Source document
The document to which one or more style sheets apply. This is encoded in some language that represents the document as a tree of elements. Each element consists of a name that identifies the type of element, optionally a number of attributes, and a (possibly empty) content. For example, the source document could be an XML or SGML instance.
Document language
The encoding language of the source document (e.g., HTML, XHTML, or SVG). CSS is used to describe the presentation of document languages and CSS does not change the underlying semantics of the document languages.
(My emphasis).
The primary possibilities to consider in deciding whether whether to use CSS as opposed to XSLT strike me as being:
Does it make sense to transform the XML document into a different structure (e.g. XHTML) the better to represent the semantics of the document?
Is the semantic structure of the document sufficient in itself, such that only presentational styling needs to be applied?
If you have some pretty arbitrary and meaningless XML - something like <data><column><row><value>1</value><value>foo</value></row></column></data> then the XSLT route would make sense. If however you have a document that has its own clearly defined semantics (e.g. an SVG file, or one of any number of XML applications) and all you want to do is make the headings stand out and the font look nice, then CSS is fine.
Ultimately, do the simplest thing that could possibly work. CSS - at least from version 2 onwards - was specifically designed to be language-agnostic (that is, not tied to HTML) so there's no good reason not to use it when it makes sense.
Did they mean a stylesheet? Any XML Stylesheet is different to a CSS stylesheet. XSL is sometimes refered to as a Stylesheet so you might both be right :)
Could someone give me a link, a tutorial or an already made css template for styling code snippet to add that feature to my blog ?
I seen examples in numerous blogs, but, now that i am searching for one, i can't put hands on it !
I want to be able to post a code snippet with keyword coloration, line numbers etc..
Many thanks in advance.
EDIT : i know there are some solution like prettify (thanks Developer Art) or SyntaxHighliter but i am on a platform and i can't use Javascript
Prettify is what you're looking for.
You include a bunch of JavaScript and CSS files to your pages and mark page sections that need to be prettified. Pretty much it.
manoli.net offers an online copy/paste syntax highlighter:
This tool allows you to format your
C#, VB, HTML, XML, T-SQL or MSH (code
name Monad) code for publishing on a
web site or in a blog.
The output conforms to the HTML 4.01
specification and is color-coded to
make it easier to read. The colors can
be changed by modifying the CSS style
sheet. See a sample.
And you may want to check out the Syntax Highlighter project on CodePlex (not sure how much activity it still has, though):
Syntax highlighter converts code text
to HTML where common language elements
are formatted using style sheet
classes such that the coloring scheme
can be switched or altered as simple
as replacing a CSS file. The primary
release ships as an extension for
BlogEngine.NET.
There are server side solutions for this as well, which of course depend on your server language. PHP is the ever popular choice for blogs, in which case you could use the equally popular GeSHi library.
Our Dev team had been developing enterprise web page more than 2 years ago. We are curious to know what is the best way to write a contract for CSS usage. For example, if we have a COMP, how we agree on a contract so our developers and our designers agree and we don't have to go back.
Is there a tool that is available for this type of technical writing?
What is the threadhold of information put in the CSS versus on the HTML page? Some of our designers thing that some things should go directly into the HTML page. The general opinion is that everything that is style should go in a CSS and all else in the html.
Thanks for your input.
Well, if a webpage has very specific CSS just for itself, I guess there is an argument for defining the CSS in the page, otherwise I would always have the CSS in an external file.
Try to avoid or at least minimise in-lining the CSS as a style attribute on HTML elements though, that would be a PITA to manage.
Most pages will be template driven with standard content styles, and thus the CSS styles will be defined in external files.
One thing you might want to think about are the number of CSS files - some people suggest that you should minimise this to just one file site-wide or per-template (or area of the site) to minimise HTTP requests to the server and avoid delayed CSS loading and funny looking styling up until that point.
So this "contract for CSS usage" is actually just a coding standard for HTML pages?
I'm a purist, so for me HTML is for content and structure and CSS is for layout & styling. That's really what each of them were created for.
See CSS Zen Garden for a great example of this. Same HTML and hundreds of different layouts & designs.
What are the reasons your designers give for styling to be in the HTML?
Edit: The main goal here is consistency across the site, correct? The more you have abstracted away from each page, the fewer changes you'll have to make.
The idea that the HTML should merely encode information and not style is called semantic markup. It has several advantages that you already know about, like separation of concerns, and a few that you probably haven't thought about.
If you stick to the web standards and separate your style and content you will also end up with a page that is more accessible to those with disabilities.
If you need to have some things styled differently for a specific page, use separate CSS include file for that page only and then use a CSS class on the element you want to style.
If I have style that is for a one time, single use page, I will consider putting it in the header of that page, as my templating system allows for that.
However you should never use inline styles. Even if you do a page with a block in it for a one off. That way should you find that you "one time" item becomes a site wide style, you can simply move the CSS into the external CSS file and not edit the content.