OWS-2 will address the issues of common architecture, image handling and decision-support tools, information interoperability, location-based services, and conformance and interoperability testing and evaluation.Addressing these issues represents an effort to create a consistent baseline of open geoprocessing services.
The Web Mapping Testbed (WMT), OGC's first
initiative, took place in 1999, culminating in a presentation on
1999.This initiative was a significant milestone for several reasons.
it introduced an innovative "coopetition" methodology that brought
competing vendors and their customers to work toward common objectives.
it demonstrated truly interoperable Web Services for the first time -
years before service-oriented architectures became the preferred form
distributed computing.In addition, WMT was the catalyst for explosive
in the OGC interoperability program.
The years between 1999 and 2003 were an exciting
great creative energy generating innovative open technologies.In this
timeframe, OGC technologies were validated through numerous pilot
implementations.At the same time, these experiences uncovered the need
integrate and harmonize service specifications, as well as update
standards and principles.
Since the 1999 pioneering experiments, Web
matured greatly from an IT perspective.Today major software platform
are aligned in support of standard infrastructures and technologies for
Services, and infrastructure support in the form of development tools
Architecture segment of OWS-2 will address the issue of bringing
specifications in line with today's IT standards.These standards,
include SOAP and WSDL, have matured under the sponsorship of
as W3C, OASIS, and WS-I.The Location-Based Services segment of
will expand and refine these services, as well as harmonize with
developed in various interoperability projects.OGC Location-Based
were created as a result of the OpenLS initiative in 2001 and 2002.The
Handling and Decision Support Tools portion will address the issue
integrating image processing services with other geospatial services.
section will also look at how to link together intermediate processing
to create a specific image product.
In a previous column, Interoperability
- Why it Makes Good Business Sense for Our Industry, dated Feb 13, 2004, we explored the issue of
information or semantic interoperability by examining the problems that
when we attempt to bring together GIS object models.In order to
a common communication infrastructure (set of protocols) is necessary,
is not sufficient.Standards for information structure and content must
These issues have emerged very clearly as
toward deployment of Web
Feature Servers and Geographic Markup
Language (GML) technology.The OWS-2 Information
Interoperability segment will research this topic in the context
of GML 3,
which is a powerful XML description of geospatial data model.The fact
can represent very sophisticated object models without any model
standardization has been an obstacle for interoperability.OWS-2 will
this problem by developing GML 3 schemas for various data products.
Note the term "application schema" used in the previous paragraph.An application schema describes an explicit data model, including objects, attributes, relationships, and temporality.This data model is usually bound to a specific application, such as a schema for road maintenance.On the other hand, a profile describes a subset of the full language capabilities.For example, a profile may contain simple features geometry (no arcs or parametric curves) and other simplifying assumptions.Profiles can be useful to describe the functionality that certain software applications support; for example, their ability to parse GML.
A final portion of OWS-2 deals with Conformance and Interoperability Testing and Evaluation, an issue that appears simple on the surface, but is quite complicated once you start looking at the details. Establishing that a software component is in conformance to an interface specification involves careful review of the specification and developing test suites.However, it is not easy to develop test suites that take into account sequence of operations, interface dependencies, validate interfaces independent of the test data set, and so forth.Even though conformance to the specifications will not guarantee interoperability, it is important to develop a conformance test baseline and begin addressing ways of testing interoperability.
In summary, OWS-2 is a significant initiative that will help to consolidate and harmonize the work done by OGC up to this point. Furthermore, it will bring OGC specifications in line with current IT standards, and it will advance interoperability by beginning to address the fundamental issue of semantic interoperability.