Download 1 - NetLab - George Mason University

Web Services Supporting
Simulation to Global Information Grid
Mark Pullen
George Mason University
with support from partners
Don Brutzman, NPS
Andreas Tolk, ODU
Katherine Morse, SAIC
DMSO Technical Exchange 3 Oct 03
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Extensible Modeling & Simulation Report
http://www.movesinstitute.org/xmsf
 Web-based technologies applied within an extensible framework
will enable a new generation of modeling & simulation (M&S)
applications to emerge, develop and interoperate.
 Support for operational tactical systems is a missing but essential
requirement for such M&S applications frameworks.
 The framework of Extensible Markup Language (XML)-based
languages can provide a bridge between forthcoming M&S
requirements and open/commercial web standards, while
continuing to support existing M&S technologies.
 Compatible and complementary technical approaches are now
possible for model definition, simulation execution, network-based
education, network scalability, and 2D/3D graphics views.
 The Web approach for technology, software tools, content
production and broad use provides best business cases from an
enterprise-wide (i.e. world wide) perspective.
DMSO Technical Exchange 3 Oct 03
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Web Services
• Definition: a self-contained, self-describing
unit of modularity for publishing and delivering
XML-based digital services over the Internet.
• natural extension of the concept of a resource
– sits on the network and does something we need
• accepts messages and returns replies
– encoded in XML
– peer-to-peer or client-server
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Specifying Web Services
• Externally visible behavior is described in terms
of the syntax, semantics, and sequencing of
messages exchanged between the service
provider and its client
• Described using an XML Schema vocabulary
• Web Service interface description document
specifies a contract between the service provider
and its client.
DMSO Technical Exchange 3 Oct 03
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Web Services Model
Service
Provider
Service
Consumer
Service
Registry
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XML
• Universal meta-language of the Web
• Used for data, content, messaging, and
computing to provide point-to-point
integration in a platform-neutral way
• Document structure, content and semantics
defined by XML schema
• Basis for a new generation of lightweight
application-level protocols now emerging
DMSO Technical Exchange 3 Oct 03
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Simple Object Access Protocol
(SOAP)
• XML-based, lightweight messaging protocol for
exchange of typed information in decentralized,
distributed environments
• Enables interoperability among (existing) distributed
applications running on disparate, heterogeneous
platforms using a modest infrastructure
• Guiding principles are simplicity and extensibility by
modularity.
• Does not define a programming model or require a
specific network transport.
• Simply consists of a modular packaging mechanism
and a set of encoding rules.
DMSO Technical Exchange 3 Oct 03
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Implementing Web Services
• Develop an ontology for data management
– use it to define an XML tagset
• Define the services to be provided
– any function is a candidate
– an example: digital terrain
• Provide software for each service
– new development: generally in Java
– legacy code easily wrapped to appear as a service
• Package the XML in SOAP for transmission
• Interoperate!
– examples: XDV via Web-Enabled RTI; XBML
DMSO Technical Exchange 3 Oct 03
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Critical Points
• XML is a mature technical standard for
information exchange
– and getting even better: compressed/binary form soon
– but it is useless without data management namespace
• SOAP is an effective means to transport XMLencoded data across networks
– but it is only a component of a larger system
• There is no magic here, just better technology
– software is still complex and expensive!
– but interoperation is simpler to achieve
– and technology development paid for commercially
DMSO Technical Exchange 3 Oct 03
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How Does This Relate to the GIG?
• XML/SOAP are great for data distribution
– support the Common Operating Picture
• But to get to the next level up, we still need to
deal with meta-information
– behavioral representation composability, as in XBML
• The simulation community has begun work on
Web Service Profiles to support this
• The same technologies empower the GIG
– we need to manage the namespaces and metainformation so they work together
– then M&S becomes a powerful C4I system capability
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One View of the Future
M&S
Service
Communities of Interest
Etc.
GIG
Enterprise
Services
M&S
Service
Comms
Backbone
ESM
Messaging
Discovery
Edge Users
Mediation
Collaboration
Storage
Security
User
Asst
App
M&S
Service
Net
Centric
Enterprise
Services
Notional only - does not imply one “box” per service etc.
DMSO Technical Exchange 3 Oct 03
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References
• Two key papers are available today as
handouts
• A collection of publications is at:
http://netlab.gmu.edu/xmsf/pubs
DMSO Technical Exchange 3 Oct 03
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