Saxonica specializes in XSLT and XQuery technology. If you're =
new to=20
these languages, this page tries to explain briefly what these =
languages=20
are and why you would want to use them. It also gives you some =
reasons for=20
choosing the Saxon product in preference to other=20
implementations.
XML is for publishing, =
XML is for=20
exchanging data=20
XML is now widely used both as a format for maintaining =
published=20
documents, and as a protocol for exchanging data between =
applications,=20
often between different organizations. It became successful =
because it can=20
handle information of arbitrary complexity, yet at the same time =
it is=20
essentially a very simple (and therefore inexpensive) technology. =
The=20
rules for particular kinds of XML message can be written and =
agreed by=20
means of an XML Schema, allowing errors to be detected =
automatically, and=20
because XML messages are human-readable, it is very easy to find =
and=20
resolve problems when they occur.
XML is also easy to integrate into business applications, =
thanks to the=20
wide availability of XML parsers on popular platforms such as Java =
and=20
.NET, and the increasing number of software packages (from =
relational=20
databases to office desktop applications) that are now XML-enabled =
"out of=20
the box".
XSLT: Styling and =
Transformation=20
XSLT stands for eXtensible Stylesheet Language - =
Transformation.=20
The language was designed primarily for writing stylesheets that =
enable=20
XML documents to be displayed to their readers. By writing more =
than one=20
stylesheet, you can display the same information in different ways =
to=20
different audiences, and tailor the presentation to the =
capabilities of=20
different display devices, including web browsers, conventional =
print=20
media, handheld devices, and digital TV. By authoring your =
information in=20
XML, and rendering it using XSLT, you separate the tasks of the =
content=20
author and the graphic designer, and you ensure that a uniform =
design is=20
achieved across all your content. This approach also allows you to =
change=20
the visual design without rewriting the content.
To see an example of this in action, compare the Saxon =
documentation on this site with the earlier=20
version of the same material: the only difference is a =
400-line=20
stylesheet written in XSLT.
XSLT is also used increasingly for transforming data. For =
example, if=20
you need to send electronic orders to your suppliers, then the XML =
message=20
used for this purpose will have to conform to a schema agreed with =
the=20
suppliers. If the data starts life in an Excel spreadsheet, you =
can export=20
it in XML using the built-in capabilities of Excel, and then =
transform it=20
to the format required by the agreed schema, by means of an XSLT=20
transformation.
XSLT 1.0 was defined by the World Wide Web Consortium (W3C) in =
1999.=20
Saxon was one of the first implementations. Many others followed,=20
including products from major vendors such as Microsoft, Oracle, =
and IBM.=20
Despite this competition, the Saxon XSLT 1.0 processor has been =
downloaded=20
nearly 200,000 times, as well as being bundled with many other =
software=20
products. It features regularly in the list of the top 100 =
open-source=20
software products.
XSLT 2.0 and =
Schema-Aware=20
Transformation=20
The specifications for XSLT 2.0 are now in the final stages of =
the W3C=20
development process. A Candidate Recommendation was issued =
on 3=20
November 2005. This is essentially the final stage of quality =
assurance=20
allowing any final errors to be corrected as a result of =
implementation=20
experience before the final Recommendation is published. =
Saxon is=20
the first and so far the only product to fully implement either of =
the=20
XSLT 2.0 or XQuery 1.0 Candidate Recommendations, let alone to =
implement=20
both in a single integrated package.
XSLT 2.0 adds many new features desperately needed by existing =
users.=20
These include more powerful facilities for handling text (regular=20
expressions) and structured data (grouping), which greatly =
increase the=20
range of tasks to which XSLT can be applied, especially when =
converting=20
legacy data and document formats to XML.
One of the most significant additions is that XSLT is now =
schema-aware.=20
This means that the XML Schema used to define the source and =
result=20
documents of a transformation can now be used to guide the =
compilation and=20
execution of the stylesheet. This makes stylesheet code more =
robust, it=20
speeds the debugging cycle, and it creates the potential for =
significant=20
performance improvements.
Saxon was the first processor to implement the XSLT 2.0 =
specification=20
and remains the only implementation that is anywhere near =
complete. Saxon=20
is now available in two versions: an open source product, Saxon-B, =
which=20
implements the conformance requirements for a Basic XSLT =
Processor,=20
and a commercial product, Saxon-SA, which adds the extra features =
of a=20
Schema-Aware XSLT Processor.
XQuery: The=20
Query Language for XML=20
XQuery is another language specification from W3C, produced in =
parallel=20
with XSLT 2.0. Whereas XSLT was designed primarily for document =
rendition,=20
and does data transformation almost as a sideline, XQuery was =
conceived as=20
a language for querying XML databases, in the same way as SQL is =
used for=20
querying relational databases. All the major relational database =
vendors=20
are adding XML support to their existing products, and new =
Native XML=20
Databases are also appearing. These products all use XQuery to =
access=20
the data.
Like XSLT, XQuery can also be used to transform XML messages =
from one=20
format to another. The language is less powerful than XSLT 2.0, =
but=20
usability studies have shown that it is easier for users to learn, =
and=20
there are also indications that it is easier for vendors to =
optimize.
XQuery and XSLT have much in common. Both languages make use of =
XPath,=20
a syntax for finding your way around the structure of an XML =
document.=20
Both languages share the same data model and type system, and the =
same=20
function library, which means that the two languages can work =
together=20
well in a single application. For example, you can use XQuery to =
extract=20
data from an XML database, and XSLT to present the results to =
users on the=20
web.
Why Saxon?=20
The Saxon-SA product includes within a single package:
A schema-aware XSLT 2.0 processor=20
A schema-aware XQuery 1.0 processor=20
An XPath processor that can be called from Java applications =
A free-standing XML Schema validator.
Saxon is written in 100% Java and therefore runs on any popular =
platform.
In the six years that Saxon has been available, it has =
established a=20
reputation for fast performance, the highest level of conformance =
to the=20
W3C specifications, excellent diagnostics, technical innovation, =
and=20
responsive technical support direct from the original =
developer.
XSLT 2.0 enables you to tackle more complex transformation =
problems,=20
and makes many routine tasks vastly simpler. This makes =
experienced=20
developers more productive, and enables new users to learn the =
language=20
more quickly. Although Saxon first provided XSLT 2.0 support over =
two=20
years ago, it remains the only implementation that is anywhere =
near=20
complete.
Saxon-SA completes the picture by offering the first =
schema-aware=20
transformation engine, allowing you to use the schemas for your =
source and=20
target XML documents to guide the transformation process both at =
compile=20
time and at execution time.
The Saxon XSLT engine supports standard Java application =
programming=20
interfaces, which means you only need to change a single =
environment=20
variable to use Saxon in place of the processor bundled with your =
Java=20
Development Kit. Many users have reported that this has speeded up =
applications tenfold.
Since mid-2003 Saxon has also included an XQuery 1.0 processor. =
This=20
gives you a choice of languages supported by the same underlying =
engine.=20
Saxon is the only product to offer XSLT and XQuery in an =
integrated=20
package, allowing you to use each language for the things it does =
best.=20
The two interfaces are complementary: for example you can write a =
function=20
library in XQuery, and call the functions from your XSLT =
stylesheets.=20
Saxon has established a reputation as the XQuery engine of choice, =
as=20
shown by the number of vendors who are integrating it into their =
XML=20
development environments.
A word of advice, though: Saxon is not an XML database. =
Users have=20
successfully used Saxon to process XML datasets up to 200Mbytes in =
size,=20
but the product does not attempt to offer the kind of facilities=20
associated with a traditional database, such as transactions, =
concurrency,=20
and recovery.
Finally, Saxon-SA offers an alternative choice of XML Schema =
processor.=20
XML Schema is a notoriously complex specification, and until now =
there=20
have been few implementations of the standard to choose from. =
Because the=20
standard is so complex, there are often discrepancies between the =
results=20
that these produce; the products are also notorious for the =
difficulty in=20
understanding their error messages when a document is found to be =
invalid.=20
If you are dissatisfied with your existing schema processor, Saxon =
provides an alternative. Use it alongside your existing processor =
to get a=20
second opinion on the validity of your documents, perhaps =
expressed in=20
language that is easier to understand. In time, you will probably =
find=20
yourself using Saxon as your first choice of schema =
processor.
What is Saxonica?=20
Saxonica is a company created by the developer of Saxon, =
Michael Kay,=20
to bring the technology to the commercial market. The existence of =
the=20
company will ensure continued investment in moving the Saxon =
technology=20
forwards, and remove the risk associated with using open-source =
software=20
that has no support infrastructure.
The development of Saxon has pioneered a new way of creating =
software:=20
solo development. Unlike conventional development techniques used =
both in=20
commercial and open-source projects, there is no development team, =
and=20
therefore no time wasted in meetings and coordination. The =
designer is the=20
implementor. The most important result is that there are no messy=20
compromises in the design. The approach shares many of the =
characteristics=20
popularized under the name Extreme Programming, but takes =
it a step=20
further. It's a high-risk approach to software development, but =
when it=20
works, the result is an unprecedented level of productivity,=20
responsiveness to new requirements, and software quality. The =
success of=20
Saxon is sufficient proof that the approach can indeed work. In =
software=20
as in other creative activities, the best results are often =
produced by=20
individuals working alone.
Michael Kay, the developer of Saxon, has nearly thirty years'=20
experience in the software industry, acting as lead designer on a=20
succession of software projects, most of which involved large =
development=20
teams. He held one of the most senior technical positions in ICL, =
a $4bn=20
software and services company, now part of Fujitsu. His knowledge =
of XSLT=20
and XQuery is second to none: he is the editor of the XSLT 2.0=20
specification, a joint editor of XPath 2.0, and an invited expert =
on the=20
XQuery Working Group. He is also the author of the best-selling =
XSLT=20
Programmer's Reference from Wrox Press, recently published in =
a new=20
edition (in two volumes) covering XSLT 2.0 and XPath 2.0.
Saxonica will preserve the unique characteristics that have =
made Saxon=20
so successful, notably the speed of development, the direct =
relationship=20
between developer and user, and the quality of the product. At the =
same=20
time it will put this on a commercial footing, enabling users of =
the=20
technology to have confidence in its stability and its=20
future.
![3D""=20](3D"http://www.saxonica.com/img/text_blue_dot.gif")