Article about binary XML by David Geer

Page 1

Computer

I N D U S T R Y T R E N D S

Published by the IEEE Computer Society

ith its ability to enable

data interoperability be-

tween applications on dif-

ferent platforms, XML

has become integral to

many critical enterprise technologies.

For example, XML enhances e-com-

merce, communication between busi-

nesses, and companies’ internal inte-

gration of data from multiple sources,

noted analyst Randy Heffner with

Forrester Research, a market-analysis

firm.

XML use is thus increasing rapidly.

Analyst Ron Schmelzer with market-

research firm ZapThink predicted

XML will rise from 3 percent of global

network traffic in 2003 to 24 percent

by 2006, as Figure 1 shows, and to at

least 40 percent by 2008.

However, XML’s growing imple-

mentation raises a key concern:

Because it provides considerable meta-

data about each element of a docu-

ment’s content, XML files can include

a great deal of data. They can thus be

inefficient to process and can burden a

company’s network, processor, and

storage infrastructures, explained IBM

Distinguished Engineer Jerry Cuomo.

“XML is extremely wasteful in how

much space it needs to use for the

amount of true data that it is sending,”

said Jeff Lamb, chief technology offi-

cer of Leader Technologies, which uses

XML in teleconferencing applications.

Nonetheless, said Heffner, “XML

adds intelligence on top of data in

motion to make that data more man-

ageable across vast technical bound-

aries. XML is so important that the

industry is looking for ways to make

its data load more manageable.”

Proponents say a thinner binary

XML will help. XML currently uses

only a plain-text format.

The World Wide Web Consortium

(W3C), which oversees and manages

XML’s development as a standard, and

Sun Microsystems are working on

binary XML formats.

Some industry observers have

expressed concern that multiple for-

mats or proprietary implementations

of binary XML could lead to incom-

patible versions, which would reduce

the openness that makes the technol-

ogy valuable.

XML’S PROBLEMS

The W3C started work on XML in

1996 as a way to enable data interop-

erability over the Internet. The con-

sortium approved the standard’s first

version in 1998.

A key factor driving the standard’s

development was increased Internet

and network usage requiring compa-

nies on different platforms to be able

to communicate. Many businesses also

wanted to make legacy data available

to new Web-based applications.

How XML works

XML is a markup metalanguage

that can define a set of languages for

use with structured data in online doc-

uments. Any organization can develop

its own XML-based language with its

own set of markup tags. For example,

a group of retailers could agree to use

the same set of tags for categories of

data—such as “customer name” or

“price per unit”—on a product order

form.

A typical XML file also includes

information about a document unre-

lated to content, such as the encryption

used and the programs that must be

executed as a result of or as part of

processing the file.

The XML document type definition

describes a document’s metadata

rules—identifying markups, stating

which elements can appear, and noting

how they can be structured—to the

applications that must work with it.

XML documents are written and

stored as text, and documents are read

via either text editors or XML parsers.

By enabling cross-platform com-

munications, XML eliminates the need

to write multiple versions of docu-

ments or to use costly and complex

middleware. However, the files contain

considerably more information than

just the content they are communi-

cating.

XML is the basis for important tech-

nologies such as Web services and

important standards such as the Simple

Object Access Protocol, a way for a

program running in one operating sys-

tem to communicate with a program

running in another by using HTTP and

XML as the information-exchange

mechanisms.

Will Binary XML

Speed Network

Traffic?

David Geer

Published by the IEEE Computer Society

Page 2

April 2005

more complex and rich XML-based

applications.

Thus, the leading proposal to allevi-

ate XML’s performance hit is binary

XML, a format that optimizes docu-

ments for faster handling.

W3C specifications

The W3C has formed the Binary

Characterization Working Group

(www.w3.org/XML/Binary/) to study

binary XML. The working group has

issued three recommendations—

backed by software vendors such as

BEA Systems, IBM, and Microsoft—

designed to make handling XML files

more efficient.

“All three of these specifications

have reached the final stage of the

W3C recommendation track process,”

said Yves Lafon, a W3C XML proto-

col activity leader who also partici-

pates in the working group.

XML Binary Optimized Packaging.

XOP makes XML files smaller by

extracting binary parts such as images,

sending them as a separate package

with the document, and providing a

uniform resource identifier as a link

that recipient systems can use to access

the extracted material, explained

Lafon.

Currently, images and other binary

data in a standard XML document

must be encoded in base64 to be

processed with the rest of the file.

Performance hit

Standard XML is bigger and, more

importantly, less efficient to process

than a binary version would be,

thereby slowing the performance of

databases and other systems that han-

dle XML documents.

For example, IBM’s Cuomo said,

“You have information in a database

that is SQL compatible. You get result

sets out of the database and, in our

case, you put it into Java Object for-

mat, convert it to XML and then to

HTML before you send it to the end

user.” The process must be reversed

when the user sends back material,

Cuomo explained. “This consumes

MIPS,” he noted.

Using XML also causes Web services,

which are becoming increasingly pop-

ular, to generate considerable traffic.

In addition, said Glenn Reid, CEO

of Five Across, a Web development firm

that works with XML, “You can’t

really start to process an XML file until

you’ve received the entire thing.”

Because of the syntax, systems must

read to the end of an XML document

before determining the data structure.

On the other hand, systems can process

some file types as they receive them.

SOLVING THE PROBLEM

One approach to solving XML-