I am assuming a basic knowledge of web and web2 technologies;  these articles are intended to assist users in updating their projects to be ready for web3.

Basic concepts

URI

When using semantic information architectures,  any artifact may be addressed by a symbol known as a URI or “unique resource indicator”.  By artifact we mean any kind of information at all.

For example “rdf:type”  is a property that may exist for any meta data;  it is referenced by the following URI “http://www.w3.org/1999/02/22-rdf-syntax-ns#type”.  In this case, the URI is also a URL meaning that you can go to this address in your browser (unless you can  read xml/rdf or you are a machine, this will not make much sense).  However, there is no requirement for a URI to address anything over the internet. nor for it to return anything meaningful  if it does.

A URI is similar to a URL in that it has the same token structure.  However a URL is assumed to be directly addressable over the internet, whereas a URI is an identifier.  URIs will often start with “http:” – this is merely a convention and does not mean that any web content will exist at that location.

Meta-Data

Meta-data means information about information.   Humans do not generally use meta-data themselves, however to classify documents using machines, we need an easy way to identify which information is contained in which document.  We also need to be able to embed information in the document.

For example, say we have document X.  Within X, part of the text will represent the title of the document, part will represent for example the author, and so on.  A human may easily discern which part of the text refers to which type;  however, for a machine there exists no easy way to distinguish parts of the document.   For this reason we use meta-tags, either within the document or in a separate meta-document, to tell the machine that part A refers to the title, part B to the author, C to the date.

The semantic web exisits to define meta-data around data that we already have, and to create concept maps called ontologies, describing the various types of meta-data.

Ontologies

An ontology represents a classification system by which we may categorize meta-data.  For example, the Dublin Core ontology contains properties such as “dc:title” and “dc:author” which refer directly to the title and the author of the document respectively.

Ontologies, and meta-data, are arranged in structures known as graphs.  Within these structures we have two types of entity;  nodes and arcs.  Nodes represent individuals or items within the graph;  arcs represent the relations between them.  A node has an identifier (in RDF we use the URI to identify any unique instance);  an arc has two nodes (in RDF we call these Subject and Object) and a predicate which specifies the type of relation,.  For example, “rdf:instanceOf” represents a predicate which links an individual to the definition of the type that the individual represents.

A URI forms a functional identifier for a node;  that is, any two elements with the same URI, refer to the same node.

Types

Any individual in Web3 must have a type;  we specify the type using the “instanceOf” property (in rdf).  Basic types are simple definitions, for example we may create a type “car” which has a supertype “automobile”.  However the semantic web allows us to create more complex types using built-in rules; if our software has inferencing capabilities. we may make full use of these.  Here is an example:  we can define a type “4 wheeled objects” where the property “numberOfWheels” is equal to 4.  If we create an individual, and assign it the property “numberOfWheels” with the value 4,  our software will automatically infer that our individual is a member of the type “4 wheeled objects” with no further effort on our part.

Properties

Properties are assignments of some artifact, to another artifact.  Two types of properties exists;  object properties, where the value of the property represents another individual, and data properties, where the value of the property represents a known data type such as string or integer.  Much like types, properties may be arranged in a heirarchy with the more general properties higher in the graph.

Individuals

An individual represents an instance of a type;  this is similar to an “object” in oop.  Basically, it represents a single “thing” rather than a type of thing.

Core Ontologies

There now follows a list of the most common ontologies

Dublin Core

Basic meta-data such as author, copyright, and other document related artifacts.

FOAF – Friend-of-a-friend

This ontology deals with relationships between people.  For example, I could use “foaf:knows” in my document when linking to the homepages of people that I know.

SIOC Senantically Interlinked Online Communities

Similar to FOAF;  allows me to specify metadata relating to social networking.

SKOS Simple Knowledge Organization System

Deals with concepts, and allows classification by grouping concepts into schemas.  One may also specify semantic relationships between concepts; for exmaple,  the “skos:broader” property links to a conecpt more general that the concept it links from (ie trees->plants, kilogram->wieght measurement, fly->insect).

Hopefully this basic guide will start you off;   in the next part of the series, I will explain the various formats that may be used to express semantic meta data,  and show you how to start using these right away in your web content.

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WYSIWYG Editors

These editors include a preview of the web page, and allow you to edit page elements directly in-place on the page.

However, the previews are never quite the same as the actual page displayed by the browser and should only be used as a guide.  These editors are great for pages using html formating, generally composed of tables with fixed size rows and columns.  Formating is generally done inline with much less use being made of external stylesheets.  Use these editors if you are doing static html such as landing pages, click-throughs and small sites with only one or two articles.

Having said that, Amaya from W3C features extensive CSS editing capabilities and an inline editor.  The renderer however is specific to Amaya so you must preview your pages in firefox to see how they will look online.  This is always advisable anyhow.

Kompozer (formerly NVU)

This is from the mozilla authors and incorporates an embedded firefox preview.  An FTP uploader is included a-la dreamweaver; however I find these unecessary because they are never quite as easy to use as standalone FTP tools such as FileZilla and CuteFTP.

The in-place editor is great; its based on the gecko engine which powers firefox and others, and so it gives you an almost exact preview of your how your site will look online.

Unfortunately this software seems to be rather unstable on both linux and windows, and development seems to have ground to a halt.  This is OK if you dont mind saving your work as you edit, and restarting the editor every time it breaks.   You may find that the advantages of the embedded browser and the in-place editor make this worth your while.

Amaya

Source: Freebase

This one is from w3 (the www consortium) and has its own page renderer called libwww.  Pages built using this package may not look the same as in firefox – you should always check your pages in all browsers anyway before you upload them.

The great thing about Amaya is that you can edit any page whilst you are browsing.  You can switch between browse and edit modes.

Amaya makes a lot of use of inline CSS;  for example, when the user bolds some text, instead of using depracated tags such as “<b></b>” amaya will create a “<span></span>”  element and insert the style inline using the style attribute.  This makes it much easier to separate formatting from layout;  you can extract the inline styles and create css classes which you can then apply to any page element.

It has a UI unlike most other software,  which takes some getting used to,  designed for fast editing using keyboard shortcuts.

Amaya lacks any support for frames or javascript, but does support SVG, math, and scientific notation, on top of its support for html and css.

Amaya is published by the w3c (worldwide web consortium).  Binary releases are here, and the source code can be downloaded here.

The Eclipse Web Tool Platform

Eclipse WTP has a built in page editor but this is not as accessible as other software.  The html editor is much better and eclipse has a built in web browser, so these are better used together rather than the in-place editor, until the team release an improved version.

HTML Editors

These editors are for editing html source code and do not feature in-place editing;  they do however feature extensive html helper functions and are great for editing javascript, and dom-based pages which utilize css for the formating and html for the layout.

BlueFish

Bluefish is a fairly compact html editor providing all the functions you  need to edit html by hand.  It is great for advanced authors because of the lack of restrictions (you can include non-html code without difficulty) and its simplicity makes it great for small systems.  It has an extensive feature set, including suport for most common language protocols.

On linux you should install it using your distributions package manger, or you can download the sourcecode from the website here.

On windows you can download a port from Google Code here.

Eclipse Web Tools

The html editor is fine and makes full use of the eclipse UI features, such as code-complete, auto-suggest, outline and properties views, and is pretty much complete in terms of its html implementation.    Eclipse  WTP also contains a javascript editor with library support, and a php editor is available again with library support.  It is mainly a developers platform and is not directly set up for website creation. – you may have to download additional tools and do some configuring.  If you run your own servers or create software in any language, eclipse will do the bulk of the workload and is easy to extend with its system of features, plugins and web-based update sites.  FTP support is also available, as is shell access and a multitude of other services, using the RSE (Remote Systems Explorer) which is also fully extensible.

Eclipse does have an inline page editor but it is not really production ready – selecting areas is quite difficult because the autonavigation does not work as well as it could, and  the preview pane will often hide page elements and gets the sizes wrong.

Eclipse can be downloaded via the main site at eclipse.org.

Conclusions

All in all, amaya is the easiest to use out-of-the-box, and is great for creating simple pages very quickly especially when they are based on existing pages.  It has no dynamic capabilities or script support.

Amaya will get you going  fast and is small enough not to interfere with other processes;  it fails on certain code but not too often; when it fails it simply vanishes and does not seem to bring down the entire system.  And it keeps backups.  If you want to be sure of w3c compliance, check your pages in Amaya.

Komposer is great for testing html/javascript combinations, and for composing html tahle based pages; it is a “poor mans dreamweaver”.  Instability is the main failing point of this tool;  development seems to have become stagnant.

Bluefish will take you places no other editor can with its ability to open 3000+ files; regex find and replace with subexpressions; wildcard file open; inline pipes using external tools such sed, awk or your own bash script; custom dialogs and key bindings, and it is very compact fitting neatly into your backpack.  This link is to the full feature list.

I`ll stick with eclipse for my php and javascript, use amaya to create layouts, kompozer for my landing pages and for page templates, bluefish for fast and easy direct editing of the source code.

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