Program Executive Office
(PEO) Interchange XML Initiative (PIXIT)
By Dr. Joseph
J. Molitoris
Chair, PEO
Interchange XML Initiative
What
is the PEO Interchange XML Initiative (PIXIT)? It is a working group within the PEO Interchange. What is the PEO Interchange? This MITRE-enabled effort began with
meetings between the Army and Air Force C2 (Command and Control) Program
Executive Office (PEO) in late 1999.
Navy and DISA participation was added around May 2000, and the Marine
Corps joined the fray in December 2000.
The current executive participants are Army PEO C3S, Navy SPAWARSYSCOM,
USAF PEO for C2 Programs, DISA Information Engineering, and USMC Systems
Command. The PIXIT research described
here was performed over the past year and presented to the PEOs and MITRE
groups on several occasions.
What
is XML? XML, as a method of structuring data in a
text or Unicode character file, forms the potential common link between many
disparate and stove-piped systems that are now deployed by DOD, FAA, IRS, and other
government agencies. Since XML is text,
it can be edited by an ordinary text editor such as Microsoft Notepad or any
UNIX text editor [1].
Although now a “techie” thing, XML is rather
broad in its scope and promise as an emerging technology. After considerable debate, the PEO
Interchange XML Initiative (PIXIT) has concluded that the PEOs would benefit
from focusing on XML as an enabling technology to achieve better
interoperability [2]. This paves the
way for the pervasive use of XML within flagship programs over the next few
years, as well as the planned 2002 release of XML-MTF (message text format
[3]). Our conclusions and reasoning may
apply to other sponsors that MITRE supports, so we provide the business and
technical case for XML use here.
As Major General Steven Boutelle of PEO C3S
recently noted in an interview with Military IT magazine: “The Web browser is
here to stay. XML allows us to take the
next giant step in managing information.”
XML
is one of several web technologies that are emerging now, some of which can be
leveraged by the Army, Air Force, Navy, and within other government
agencies. The PEOs are just beginning
to feel the force of directives, policy, and mandates from the Pentagon that
relate to these Web technologies. The
reasoning behind this initiative is that what works effectively for so many
millions of users should help improve military interoperability as well. Furthermore, XML is a family of technologies
consisting of the basic XML specifications of 1998, as well as more recent
World Wide Web Consortium (W3C) and other recommendations on Schema,
StyleSheets (CSS and XSL), Namespaces, transformations (XSLT), and other
matters [4].
Is
XML ready for prime time? The basic XML specification of 1998 came from working group efforts of
1996. The second edition of that
specification was published in 2000.
There are a number of related recommendations that were released by W3C
over the 1996-2000 period. Major
software companies (Microsoft, Sun, IBM, etc.) have implemented the
specification in their systems. Only in
the encryption/security and query area are the specifications not fully mature,
but that development is expected sometime in 2001. Thus, XML is ready for prime time with respect to basic XML
functionality, style sheets for viewing, document object model for programming
access, wireless applications markup and protocols, and DTDs/schema for
data/information specification.
What
is the recent history of XML from the point of view of a MITREITE and refugee
scientist? In the
mid-1990’s, the Internet and World Wide Web became the hot technology for
everyone, including military and government personnel. One of the enablers there was HTML
(hypertext markup language). Because of
the simplicity of HTML—it is not a programming language, you only need a text
editor to write it, and you only need a browser to view the display—the Web
moved forward exponentially from a few million users to hundreds of millions of
users today.
XML, like HTML, is rather simple. XML is not a programming language, although
it may evolve many of those capabilities.
One needs only a text editor to write it and a browser to view the
display. Sure, the techies will extend
(read “improve”) it and add more complicated twists as they did with HTML (this
is already happening), but this need not take away from the simplicity and
utility of XML. XML is an extended
markup language which means that the programmer, developer, or a community of
parties define common tags (technically elements) that enable better
interoperability and easier information exchange [5].
When
should XML be used? XML should be used by
government programs and agencies where it is mandated and/or where it makes
sense. XML is not a silver bullet for
all information processing woes, but it has the potential to increase
interoperability if used intelligently.
Currently, XML is mandated for tagged data items by the JTA (joint
technical architecture) and JTA-A (JTA-Army) within DOD. There are at least one hundred people
working on XML projects throughout MITRE and even more efforts within other
companies and numerous government agencies [6].
XML
should be used in flagship programs, messaging, databases, office products, and
other processing where information transfer between disparate systems is
important and where interoperability requires improvement. XML need not be used in
all cases, but should be considered as a document/data definition format in the
same way that HTML is considered and utilized as a display format. Furthermore, XML can also help with the
display of data with the new XHTML specification and the transformation
properties of CSS, XSL, and XSLT.
What
is the potential impact of using XML? The proper use of XML can save the government money
in system deployment and increased interoperability. The potential benefits
include cost savings, reduced training time, interoperability within each
service (or agency), and interoperability between the services (or agencies).
The use of XML can occur at several levels:
§
Internal to a particular system
§
Between two or more single
service/department systems
§
Between two or more multiple
service/department systems.
The last two categories could be called the
external use of XML, and coordination between the affected programs/communities
of interest is important. This
coordination can occur informally or formally and is discussed later under the
topic of communities
of interest (COI). The current commercial models for
coordination (consortia, partnerships, and standardization groups) are all good
models for defense and government departments.
Do
you have to rewrite entire software systems to utilize XML? No. XML may be incorporated into the appropriate pieces of a
software system’s architecture in the same way that HTML and browsers were
incorporated in the 1990’s. Naturally,
if one were just beginning a software system or light (PC) version of an
existing system, then it would be easier to implement XML than with an existing
system that was not designed for Web technology. And the depth of penetration of XML into the architecture may
relate to the amount of interoperability achieved.
However,
flat files and database queries can be converted to XML and vice versa. Agencies that have an installed based of
SGML should have an easier time with transitioning to XML than those with only
HTML experience.
Can
One buy XML? No. One can buy many products that support
XML (and some are freely available), including browsers, operating systems,
office products, databases, and portals.
But someone has to produce the XML that a particular organization needs,
unless the specific XML already exists in a commercial or government
repository.
Would
one have a hard time using XML? Not
necessarily. The basics of XML are fairly simple. The hard part is the human
agreement between the developers or managers of disparate systems who need to
agree on the tag or element names.
Thus, within DOD, communities of interest (COI) need to form agreements
to use XML. These COIs parallel the
consortia, standards bodies, and corporate partnerships that occur in the
commercial marketplace to forge agreements about the common use of XML. A COI can be as small as a single program
within a PEO or as large as several PEOs working together with respect to a
particular mission area. If agreement
is not possible, then it is still easy and fairly cost effective to design
translators between different XML systems.
When
should XML not be used? When the system or group of
systems already operates acceptably and XML use is not mandated or considered
appropriate.
What
does one need to get started using XML? As with any Web or software development project, a
clear vision of requirements and data/information exchange needs is
helpful. In terms of tools, the
following items—at a minimum—are needed:
1.
Text
editor (e.g. Microsoft Notepad on Windows or a UNIX text editor on a UNIX
system)
2.
An
up-to-date browser (Internet Explorer, Netscape Navigator, or others with XML
support)
3.
Parser,
unless the parsing in the browser is sufficient (e.g. XML Spy, MSXML, Larval)
4.
DTD
or schema editor unless the DTD/schema checking of the browser is sufficient
(e.g. XML Authority)
5.
(optional)
XML enabled database tool for database work (from Oracle or other vendors)
6.
(optional)
XML programming language access (XML Document Object Model or other interface)
In
using XML, what text editor or development environment should be used? Microsoft Notepad or any
plain text editor will work. The user
creates XML files in accordance with the XML specification. HTML or SGML experience is particularly
useful for a new XML developer. There
are also more expensive development environments from several vendors
(Extensibility, SoftQuad, and i4i, to name a few). Some of these, such as the i4i product, are plug-ins to Microsoft
Word for ease of use.
In
using XML, which browser should be used? Different browsers have different levels of
support for XML. It is fairly safe to
use the latest version of Internet Explorer (version greater than 5.0) or
Netscape Navigator (version 6.0 or above).
Most modern browsers have at least limited support for XML.
In
using XMLs, should schemas or DTDs be used? This
is the choice of the developer. Many
products already use DTDs, but it is not hard to convert to schema should they be
needed. Schema are in general more
capable and more complicated, but light versions of schema such as the RELAX
(REgular LAnguage description for XML) approach are available as well. A recent space ontology schema [7] has been
developed for the Air Force by MITRE, and an evaluation of the different schema
products has also been completed [8].
Extensibility makes an XML DTD and schema editor called XML Authority
that is fairly easy to use and relatively inexpensive.
What
areas of XML activity are appropriate for DOD and government agencies?
Our
recommendations to the PEOs have potential application throughout DOD (and,
indeed, in other government departments and systems). In order for XML (a COTS technology) to be successfully adopted
(technology transition) for military use, four areas must be addressed:
1.
Policy - DOD, DISA, Army, Air Force, Navy,
Marine Corps, NATO or affected departments and agencies and agencies
2.
Cross-service interoperability
3.
Programmatic, e.g. PMs within Army, Navy,
Air Force, Marine Corps
4.
Technical – Actual technical implementation.
Success with XML (unless it occurs by
grassroots activities, as it did with HTML) must address these four problem
levels.
From
Stovepiped to Interoperable Systems. We have shown elsewhere [2] how military systems
are making use of browsers and Web markup languages such as HTML and XML. More universal browser use as a common
interface and the wider use of HTML and XML should be planned for. This will help complete the movement from
stovepiped and proprietary to Internet standard based systems, thereby enabling
greater ease of use and interoperability.
The defense and government departments
should plan to more efficiently use available limited bandwidth as systems are
fielded. As faster computers and
greater bandwidth become available, these should be deployed when and where
cost effective in order to ease the strain on processors and networks.
As lessons are learned from experimentation
with Web technologies like XML, the government should move from these
demonstrations and proofs of concept to fielding of the best and most cost
effective products. This is now in
progress with several programs.
Interoperability,
the Holy Grail. Interoperability is defined
in different ways by different agencies. Here, two definitions within the joint military community from
Joint Publication 1-02 are noted. Of
course, interoperability is important for companies and the consumer/user/warrior
as well.
At the simplest level, interoperability
means 1) providing and accepting services (data, messages, information) and 2)
exchanging information directly and satisfactorily between two or more systems.
The Internet and Web technology [5] have
allowed us to achieve considerable interoperability over the last decade. XML allows us to move a step further. XML is aimed most obviously, but
not exclusively, at the data level of interoperability [9]. Our challenge is to achieve better interoperability between government
systems for our sponsors.
Interoperability could encompass multiple message formats, file formats,
data and database formats, and operators.
XML is designed for this type of heterogeneous environment.
A
Multiyear Vision. XML is already being used in
prototype efforts in every community of interest, from the FAA [10] to the IRS
and DOD [11]. Within DOD, efforts range
from those within the intelligence community [12] to messaging standards bodies
[3].
Following
is a vision of XML’s place in PEO (and other agency) systems beyond the next
few months. The application of XML to
PEO systems over the next few years has great potential to improve information
exchange and interoperability. First,
it can work with message processing (CMP and IRIS). Then it can work with database exchange, beginning with mission
critical databases. Finally, it can
work with a potentially more integrated joint C3 architecture.
Major software companies—such as Microsoft, Sun, IBM, Sybase, Informix,
and Oracle—are integrating XML within their products in the same way that HTML
was integrated just a few years ago. This is because XML is a powerful method
of structuring data in a text or Unicode character file. XML files can handle data/text information,
as well as pointers to binary files. As
such, XML can be important for information exchange between applications and/or
between clients and servers.
Following
are recommendations for three areas where XML should be applied (where
appropriate):
§
Flagship
programs desiring to better synchronize and interoperate. This is a two-part recommendation: 1) messaging and 2) databases. Messaging is the easier task in XML,
enabling the CMP and IRIS products.
§
Leveraging
COTS XML software (browsers and parsers, operating system and databases, other
tools.
§
Developing,
supporting, and implementing XML policy and guidelines.
It is very important that the policy efforts
at the top (DOD and service CIO groups) are consistent with the intelligent
application of XML by developers to improve software products. This will only occur with good feedback and
communication between all stakeholders.
The PEO Interchange effort and the working groups can help make this
happen.
Acknowledgements. I want to thank and acknowledge contributions from Frank Ruscil,
MITRE Eatontown and Ed Masek and Dan Winkowski of MITRE Langley. At the executive level, I am grateful to
Beth Meinert, Danny Demarinis, MITRE Eatontown, and Dr. Joe DeRosa, MITRE
Bedford.
References
[1] XML
Elements of Style, Simon St. Laurent, NY: McGraw Hill, 2000.
[2] XML
Technology, Dr. Joe Molitoris, MITRE Eatontown, November 8, 2000, and other
more recent briefings and publications including the MITRE IT Adviser, March
2001.
[3] XML-MTF,
Mike Cokus, MITRE Langley, several briefings and documents.
[4] See www.w3.org for further information.
[5] Web Technology briefings by Bruce Binney
(MITRE San Diego), Lynne Spruill, and Dr. Joe Molitoris expand on this area.
[6] A listing of known XML efforts is
available on request.
[7] Space Ontology Schema, Dan Brandsma and
Mary Pulvermacher, MITRE Colorado Springs.
[8] Relational Databases and XML, Alan
Bernstein, MITRE Eatontown, January 2001.
[9] Mike Bean, MITRE Bedford.
[10] Jon Mack, MITRE Atlantic City, work in
progress.
[11] XML
Within Government, Dr. Joe Molitoris, MITRE Eatontown, December 2000.
[12] Tim Croy, MITRE Maryland, January 2001,
work in progress.
Acronyms
BFA Battlefield
functional area
CMP Common
message processor
COTS Commercial
off the shelf
CSS Cascading
style sheets
DISA Defense
information systems agency
DOD Department
of defense
DTD Document
type definition
HTML
Hypertext markup language
JTA Joint
technical architecture
JTA-A JTA-Army
PEO Program
executive office
PM Program
manager
RELAX Regular language description for XML
SGML Standard generalized markup language
XHTML Extensible HTML
XML Extensible
markup language
XSL Extensible
stylesheet language
XSLT Extensible
stylesheet language transformations
W3C Worldwide
web consortium
For more information, contact Dr. Joseph J. Molitoris by telephone at (732) 389 6705 or via e-mail at jmolitor@mitre.org