When was xml created

They present a method to generate DTDs from relational schemas in the presence of keys, foreign keys, and functional dependencies, which can preserve the semantics implied by functional dependencies, keys and foreign keys of relational schemas and can convert multiple tables to XML DTDs. While this is a forward step towards full semantic conversion of relational schemas to XML DTDs, they note there is still work remaining in converting further relational semantics such as multi-valued dependencies.

These do not allow a sufficient level of detail to be used in XML to relational mapping. For example, DTD can define a list to contain zero or more, or one or more elements, though it cannot define other limits.

This can specify a list to contain 2 to 5 elements for example, and can be used to ensure that an XML document is both well formed and valid against this schema. XML has proved hugely successful in the areas of document mark-up, data and meta-data sharing, enabling interoperability, and transparently transporting and storing data.

With the current level of interest in the next generation of enterprise systems, the use of XML is set to grow as it is a core technology to web services, portal development and service oriented architectures.

Wira Setiawan. Twitter LinkedIn. Widgets Connect Search. Like this: Like Loading May 28, at June 9, at The content can contain other elements, or can consist entirely of other elements, or might be empty. Attributes are named values which are given in the start tag, with the values surrounded by single or double quotations:.

There are a few other fundamentals in XML, such as processing instructions and namespaces, but elements and attributes are the heart of it.

If you are familiar with object-oriented programming, it might help to think of elements as objects and attributes as properties. When designing XML applications, it can be hard to decide what should be an element and what should be an attribute.

To some extent this is a matter of taste. Some XML is more element-centric, some more attribute-centric. A well-formed XML document is one that conforms to rules, such as having only one root element, all start tags have matching end tags, elements may not overlap, and so on. You can make up elements and attributes as you go along, and still end up with a well-formed document.

It is usually more useful to validate the document according to an agreed schema, of which XHTML is an example. A key advantage of XML Schema is support for strong data types, such as string, float, boolean, decimal and dateTime. Valid XML is both well-formed and validated by conformance to a specified schema. Markup is information inserted into a document that computers use; in the case of SGML, markup takes the form of tags inserted into documents to mark their structure.

Descriptive markup uses markup to label the structure and other properties of information in a way that is independent of both the system it's created on and of the processing to be performed on it. Meta-languages are languages used to create vocabularies that are relevant to their information.

User defined, processing-independent markup is easier to reuse and can be processed in new and often unexpected ways. Descriptive markup also makes information independent of any particular piece of software. System-dependent and proprietary formats hinder the reuse of information and make the data owner dependent on the vendors whose software can create and manipulate those formats.

With an SGML fit for the Web, it would be easy and reliable for computers and humans to use descriptive, structural markup in their documents. To our surprise , we did it. The page XML specification could be easily learned and implemented.

XML is a meta-language that allows you to design markup languages that describes what is important to you. XML provides elements and attributes to capture logical structure and enables semantic understanding. Before we knew it, all sorts of people started using XML — best of all, doing so without the permission or guidance of the Working Group.

Database people, transaction designers, system engineers, B2B developers all crashed our party. Why, an outsider even got an article on XML published in Time magazine!

People flocked to talks given about XML; tools were created, and not by just a few but also by the largest software companies in the world. The press reported, at first with lots of misunderstanding but later with growing insight into how XML could make its mark on the Information Age.

XSLT has become a general-purpose language for transforming one XML document into another, whether for web page display or some other purpose. At this point, it was noticed that both XPointer and XSLT were developing fairly sophisticated yet incompatible syntaxes to do exactly the same thing: identify particular elements in an XML document.

Consequently, the addressing parts of both specifications were split off and combined into a third specification, XPath. A little later yet another part of XLink budded off to become XInclude, a syntax for building complex documents by combining individual documents and document fragments.

The simplest API was merely to treat the document as an object that contained other objects. Expanding this effort to cover XML was not hard.

One of the surprises during the evolution of XML was that developers adopted it more for record-like structures, such as serialized objects and database tables, than for the narrative structures for which SGML had traditionally been used. DTDs worked very well for narrative structures, but they had some limits when faced with the record-like structures developers were actually creating.

In particular, the lack of data typing and the fact that DTDs were not themselves XML documents were perceived as major problems. A number of companies and individuals began working on schema languages that addressed these deficiencies. Many of these proposals were submitted to the W3C, which formed a working group to try to merge the best parts of all of these and come up with something greater than the sum of its parts.