Introduction to XML Week 8 – Lecture 1

Generalized Markup Language 80’s90’s 60’s Toda y 86’ SGML 89’ HTML 98’ XML ebXML XBRL RosettaNet etc. XML is a simplified markup language to facilitate the exchange of information: providing both format and content A group of standards (XML, XSL, XML Schema) Is different to HTML which is a presentation language which provides no semantic information. Accenture 2001

In HTML P266 Laptop Friendly Computer Shop $1438 In XML P266 Laptop Friendly Computer Shop $1438 Both of these may look similar in your browser, but HTML tells how the data should look, while XML tells you its structure. With XML, your browser knows there is a product, and it knows the model, dealer, and price. From a group of these it could show you the cheapest product or closest dealer without going back to the server. Comparing HTML and XML p = paragraph h1 = heading level 1 br = line break

XML is expected to: Revolutionise electronic publishing by allowing for a better indexing of data and the separation of content information from display information Improve business communication by facilitating the definition and sharing of common XML formats or vocabularies as well as the transformation of differing XML formats Help facilitate the adoption of eCommerce and as content will be displayed not only on desktop web browsers, but also PDAs, cellular telephones, and whatever other devices the future may bring us Accomplish all of the above items in a simpler and more maintainable way Accenture 2001

Document types An Instance of an XML record A XML schema (XSD) or Document Type Definition (DTD) eXtensible Stylesheet Language – XSL XSL Transformation (XSLT) is the language for transforming content only XML documents into alternate formats. Once processed by the XSL stylesheet processor, the result may be a new XML document or any other text-based document such as HTML XSL Formatting Objects (XSL-FO) specification is the language for specifying presentation of page content. This is possible via use of an extensive vocabulary allowing the detailed specification of things like pagination, layout, and styling information.

XML Document Instance Order 1

The schema defines the structure of the document The schema consists of a schema element and a variety of sub elements which can be of complexType or simpleType Elements which contain sub elements or carry attributes are said to be complex Elements which contain numbers, strings, dates, etc are said to be simple Simple elements can have rules attached to them such as constraints (e.g., length, permissible values, etc)

XML Schema Order 1

Big Monitor Instance: Schema for item: Schema for serialTypes:

How do we know this is in the “right” format? The sender and receiver need to work off a common schema or DTD

An XML document can be transformed into another XML document HTML document

XML Document Instance Order 2

XML Schema Order 2

XSL Transform Order 1 -> Order 2

Enrolment process Database server Database (Oracle) Database (Sybase) Marking system BIT add ISYS2007 Connector Remember the last solution from yesterday? We will now look at the connectors in more detail.

SQL extracts change from the log tables Enrolment Database Schema For interface file Process the extract data with the schema, to create an XML file Publish the XML file of change data Parse the change file with the schema to ensure it is well formed Transform the data Into the required format using XSLT Schema of required file format Process changes to Marking system IT School marking database Network

XSL Transform Order 1 -> HTML

Industry groups are developing their own schemas XBRL – Business Reporting Language Rosetta Net ebXML These allow data to be transferred across organisation boundaries

Traditional Responses Across Organisations Interfaces EDI or Custom “standard” (e.g. integrion, SWIFT) Reinventing “interchange data structures” Validation of data passed built into each “receiving” application Data structure changes require massive rebuild & retest Problems with today’s approach Difficulties to get people to agree Difficulties to get participants to agree on technical platforms and associated costs (e.g. MQ Series, other EAI tools, etc) Standards (e.g. EDIFACT) are inadequate for industry solutions so require customisation Administration of change across organisations

XML Response to the Problem Solutions Low cost mechanism which is easy to agree on Proliferation of industry bodies to define industry schema (Accord, FiXML,CML, etc) Interchange data semantics & validation rules ubiquitously available Data can be validated by the schema before information is accepted, removing the need for each receiving application to re code validations Ready availability of skills in the marketplace XML parsers & other tools available in most languages and on most platforms Ease of data transformation to adapt to needs of sending/receiving application data structures Reduced need for “big bang” synchronisation of change associated with new data structures Shortfalls/Challenges Performance concerns (verbose) Many XML standards (DirXML, UDDI, etc) Relatively young toolset

XML Distributes the Transformation Workload The XML approach also helps multiple applications share in common data on an “information backbone” A B C D hub xform A - C xform A - B A B C D Info Bus xform A - bus xform bus - B xform bus - c Hub and SpokeInformation Bus

Multi Device Delivery - the business problem… Key Issues Separation of business application logic from presentation; Personalisation of presentation (client specifics) Minimise duplication of logic such as presentation & validation Multi language delivery The migration towards server based computing and uptake of multiple mobile devices is fuelling the need to deliver business functionality to multiple channels/devices (PDA, mobiles, etc), tailored to the attributes of that device. Generic solution This problem is usually addressed by dividing up the solution into components, each with specific responsibilities

Traditional Responses to Multi Device Delivery Solution Layer a new delivery solution for each channel/device Maintain single “application” instance Typically multiple vendors’ software required to deliver end-end solution Problems with this approach Cost & complexity (effort & infrastructure) Duplication of logic/effort Typically multiple people required to maintain individual pieces because of specialisation

XML Response to the Problem Solutions Single channel/device processing infrastructure Use XSL-FO to transform the XML document into the target format for presentaion Generally the functions available under MSXML or JAXP Shortfalls/Challenges Limits your ability to cache data at client Practicality of “write once/display many times” with usability differences between platforms Still have to develop multple XSL transformations