OGC Document 10-128

OGC Compliance Testing White Paper
By Luis Bermudez
Director of Interoperability Certification
Open Geospatial Consortium (OGC)This white paper describes the OGC Compliance Testing Program. It provides
information about:• The need for compliance testing to enable interoperability• How to obtain compliance certification• The difference between implementing and being certified• How compliance benefits providers and users of technology• The proper use of the “Certified OGC Compliant” mark• Suggested language for procurement documents• Trademark licensing fees
• An example of an OGC compliance test

Important Definitions:
OGC compliance test: A procedure that evaluates a software product for proper
implementation of an OGC standard. OGC compliance tests are available free andonline for use by developers preparing for OGC certification of their products.
OGC implementing product: A software product that uses an OGC standard. The
developer of this software product may not claim that their product is compliant withthe standard, even if their product has passed an OGC compliance certification test.
OGC compliant product: A software product that has passed the compliance test,
and that OGC has evaluated and approved as compliant. The compliance evaluation
process includes the developer submitting proper documentation to OGC(Compliance Test Package), the developer paying the appropriate Trademark
Licensing Fee, and the evaluation of the tests and documentation by OGC staff. The
developer then has the right to use the “Certified OGC Compliant” service markshown in Figure 1 and legally claim that a product is “OGC compliant”.

Figure 1. Certified OGC Compliant service mark with OGC logo
OGC Registered Compliant products: Many developers have implemented OGC
standards and many of these products are “OGC compliant”. To inform buyers, mostdevelopers offering OGC compliant products and most developers offering OGC
implementing products register their products on the OGC “Implementing” page(http://www.opengeospatial.org/resource/products).

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Standards compliance and interoperability
When properly implemented by developers, OGC standards enable different locationenabled software systems to interoperate, or work together, for improved decision
making. Widespread interoperability, a critical requirement in today’s networked world,
depends on users and providers having a way to know whether products and systems
comply with the standards that enable interoperability.
Interoperability is not just a promise. Today, dissimilar geoprocessing systems onenterprise networks and on the Web interoperate for many purposes through common
interfaces that implement OGC standards. The extent of interoperability enabled by
OGC standards and implemented in products is growing rapidly. By Sept 2010 there
were more than 600 Compliant or Implementing Products registered on the OGC web
site (http://www.opengeospatial.org/resource/products).
The new paradigm of interoperability based on correctly implemented open interface andencoding standards offers communities of users many advantages over the oldparadigm of software systems that were isolated by their proprietary interfaces andencodings:•

No single Geographic Information System (GIS), mapping tool, imaging solution, or
spatial database answers every need. Also the functions previously offered only bysuch products are now, thanks in large part to standards, becoming available asservices on the Web.

•

Geodata is everywhere. Any database record with a description of location canbecome spatial data or geodata. Any text can be parsed against a gazetteer tocapture location names and thus create geodata. Advances in remote sensing,location services, fast processors and broadband data pipes all contribute to a
growing geodata cornucopia.

•

The number of software developers offering components to deal with geographic
information is growing, not shrinking.

•It is efficient to collect data, maintain it in one place and use it many times. This isparticularly cost-effective if communities of users can find, access, and use thisinformation online. In this case they don’t need to access, retrieve and maintainwhole files and databases of information that others are responsible for.

•

The ability to seamlessly combine accurate, up-to-date data from multiple sources
opens up new possibilities for improved decision-making and makes data morevaluable.

•

The ability for multiple users, including those who are not geospatial experts, to use
data (perhaps at different levels with different permissions) also makes the data
more valuable.

•

Service Oriented Architectures (SOA), in which countless Web clients request andOGC Document 10-128

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can receive services from countless Web services, depend on open interfaces thatenable this “loose coupling” paradigm. In the SOA world, it usually isn’t enough to
say that clients can communicate with certain servers via those servers’ publishedinterfaces. It is also necessary for the interfaces to be properly implemented
according to standards. The Certified OGC Compliant service mark assures software
buyers that a server’s interfaces comply with OGC standards.
Forward-looking buyers of geospatial information systems who purchase products thatcomply with OGC standards look forward to:•

Establishment of shared information service options for their organizations and thosethey serve.

•

Streamlining of operations through online geo-information resources andimprovements in stewardship and sharing of those resources.

•

Faster, better service delivery resulting from standards-based technology delivering
the advantages of component approaches.

•

Fiscal benefits and risk reduction. Co-investing with partners in open technology
platforms and shared data reduces costs and improves information resource
manageability.

Compliance testing
An OGC compliance test is a procedure that evaluates a software product for proper
implementation of an OGC standard. OGC compliance tests are available free andonline for use by developers preparing for OGC certification of their products.

Procedure to become legally "Certified OGC Compliant"
A product’s advertising or packaging may legally carry the Certified OGC Compliant
service mark for compliance (Figure 1) if the product has passed the compliance test,
and if it has been evaluated and approved by OGC to be compliant. The complianceevaluation process includes the following steps:
1. The product developer tests a product and the product passes the online
compliance test.
2. The developer submits proper documentation to OGC (Compliance Test
Package). This includes a form with information about the passed online
compliance test.
3. OGC staff evaluates the test results and creates proper documentation.
4. The developer agrees to the OGC Trademark License Agreement.
5. The developer pays the appropriate Trademark Licensing Fee.
6. OGC grants the compliance certificate.
The mark will be valid for a particular version of a particular standard and it may only be
used if the product developer has paid for the OGC-supervised compliance test and theright to use the mark.
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Difference between implementing and being compliant
An OGC implementing product is a software product that uses an OGC standard. The
developer of this software product may not claim that their product is compliant with thestandard, even if their product has passed an OGC compliance certification test.
Implementing products might interoperate with other implementing products and with
OGC compliant products, but interoperability between two products is much more likely
when the products have both passed OGC-supervised compliance tests and carry the
Certified OGC Compliant service mark. This is because the Certified OGC Compliant
service mark certifies that the standard has been implemented correctly.
Figure 2 shows the process a developer goes through to implement and claim OGC
compliance. A developer can run an OGC compliance test (available free and online) fora particular OGC standard to determine whether or not they have correctly implemented
the standard. At this point the developer can claim that the software implements an
OGC standard. The developer can then continue the process of seeking formal OGC
certification of the product and the right to use the Certified OGC Compliant service
mark.

Figure 2: “Implementing” products and “Compliant” products.

Benefits for providers of OGC Compliant technology
For technology providers, compliance testing and use of service marks are importantbecause interoperability has become a high priority for users, who are increasingly
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insisting on formal standards compliance when they purchase software. Customers want
the Certified OGC Compliant service mark because it gives them assurance that theirproducts and solutions will be able to interoperate with other systems that have properly
implemented OGC standards. The Certified OGC Compliant service mark also gives
integrators confidence that they will be able to efficiently integrate developers' products
as components in the solutions the integrators provide.
The Certified OGC Compliant service mark gives software resellers a way to back up
their claims about compliance. OGC standards have been an important contributing
factor in the growth of the geospatial market because they have eliminated technologyimposed barriers to the wider use of geospatial data and processing. OGC compliance isincreasingly necessary for technology providers to participate in this expanded market
because more and more users understand what has happened and why it has
happened, and the users see the logic in demanding the Certified OGC Compliant
service mark. Ultimately independent software developers and resellers can increase
their market reach by delivering OGC Compliant solutions.

Benefits for buyers of OGC Compliant technology
For buyers, the Certified OGC Compliant service mark can save money and it can also
ensure user access to essential services and information. Making the user’s experience
as error-free as possible is important to maintaining the credibility of a business oragency. Accountability is also important: Who is responsible for a particular online
service? The Certified OGC Compliant service mark will probably never be seen by theagency’s or service provider’s users, but those users will get more reliable service, they
will spend less time and money manually converting between data formats, and they will
benefit from the earlier arrival of new products and services. These improvements will
provide them with more time to focus on other business-critical areas and improve
productivity associated with geospatial data management.
Interoperability – and the Certified OGC Compliant service mark – should be a major
consideration in an organization’s technology procurement policy. It provides confidence,
reduces risks, and increase systems interoperability.
Confidence in purchased products. An OGC service mark on a product gives buyers
the confidence that a product will work with another product that carries the same OGC
service mark, regardless of which company developed the product.
Reduction of technology risk. For purchasers of geospatial technology products andservices, reducing “technology risk” is an important goal, and the Certified OGC
Compliant service mark helps achieve that goal. Reducing technology risk is a software
lifecycle management issue. Organizations whose significant investments in technology
require rigorous product and system lifecycle management depend on OGC complianceto help them maintain business continuity and durability of their enterprise architectures.
In short, procurement of Certified OGC Compliant products “future-proofs” IT investment.
Increase of Systems interoperability. Certified OGC Compliant products help diverse,
distributed software components and systems to interoperate. The components may beelements of a new component-based solution, or they may be legacy systems that havebeen upgraded with interfaces that implement OGC standards. The components could
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be components purchased in the future from different developers to add functionality to asystem. Systems used by data sharing partners, now and in the future, interoperate
more reliably if those partners’ systems use Certified OGC Compliant products.

How does one know that a product is "Certified OGC Compliant"?
If a product legally carries the Certified OGC Mark in Figure 1 it is Certified OGC
Compliant.

Registry of OGC implementing and compliance products
A buyer can confirm whether the product is an “implementing product” or is “Certified
OGC compliant” by looking for the product name on the OGC Website at
http://www.opengeospatial.org/resource/products.

Proper use of the OGC Service MarkThe OGC service mark in Figure 1 must be used in conjunction with one or moreindividual OGC standard service marks such as those shown in Figure 3.
Version numbers are important – while the OGC strives to preserve backwards
compatibility, using the same version of a standard will optimize interoperability.

Figure 3. Certified OGC Compliant service marks for individual standards
Providers may use OGC service marks in product literature, on their web site, and inother sales and marketing materials to indicate that they have achieved official
compliance with one or more OGC standards.

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Enforcing standards in procurement language
Software and system buyers help their organizations, their information-sharing partners
and the larger industry when they insist on the Certified OGC Compliant service mark.
But how does one do this? How does one communicate to bidders that they must offer
OGC compliant products?
The best way to begin is to prepare a "notional architecture" document. One example ofsuch a document is the 2005 "Spatial Interoperability Demonstration Project (SIDP)
Notional Architecture Executive Summary"(http://portal.opengeospatial.org/files/?artifact_id=10687) prepared by the Open
Geospatial consortium – Australasia (OGC-A). Another example is the 2006 slide set,
"Enabling Framework - A Technical Architecture" by Martin Brewer, SLIP-EF Chief
Technical Officer at the Western Australia Department of Land Information(https://www2.landgate.wa.gov.au/slip/portal/home/latest-newsfiles/02_EFTechnicalArchitecture.pps).
A notional architecture is, to quote from the SIDP document, "... an idealized descriptionof the services and interfaces required to construct interoperable spatial infrastructure
systems. The architecture is notional in that it makes no assumptions about physicalimplementation and the only assumption made about vendors and institutions is thatthey accept and support open, non-proprietary standards.”
Such a document explains what kind of interoperability is necessary and which
standards must be implemented to provide that interoperability. Bidders must show, andbuyers must evaluate in their technical evaluations, whether or not the offerings
implement and/or are compliant with the necessary standards.
It may happen that certain desirable products have not yet implemented necessary OGC
standards, but the vendor claims that implementation and certification are pending. Or it
may be that OGC has not yet provided compliance tests for certain necessary
standards. In such cases, bidders may commit to providing the necessary
implementations and certifications as soon as these actions become possible. Suchcommitments can be negotiated and set forth in service level agreements.
Open standards are a result of demand for interoperability and requirements for dataand services to be shared across organizations and communities. The Certified OGC
Compliant service mark represents a level of professionalism that puts softwarepurchasers as well as solution providers on the most certain path to interoperability.

Suggested OGC Certification Language for Procurement texts
OGC compliance tests are available for many but not all OGC standards. The OGC isconstantly increasing the number and percentage of standards for which tests areavailable. The important thing to remember is this:Procurement language – the terms spelled out in tenders and requests for quotes(RFQs) – should require or strongly encourage vendors to offer Certified OGC Compliant
products when tests exist for OGC standards that apply to the functionality of those
products. When OGC compliance tests do not yet exist for a standard, procurement

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language should require or strongly encourage vendors to offer products that implement
OGC standards.

Digital nuts and bolts about compliance testing
To understand software compliance testing, it’s necessary to understand software
standards. Just as speakers and listeners of a human language must understand andagree to the same rules of vocabulary, grammar and pronunciation, computer systems
that exchange data and instructions must have matching interfaces that send andreceive data encoded according to strict rules. An OGC standard is a specification that
describes the matching software interfaces and data encodings necessary for aparticular kind of exchange of instructions or data. An OGC standard documents all thedetails a software developer needs to take into account when implementing softwarethat will “speak the same geospatial language” as other software programs that
implement that standard.
A compliance test determines whether a software program has correctly implemented astandard, in all its details.
Below is a brief example of a client request made to a server that implements an OGC
standard. We chose this “http://www….” example because most people use software
without ever seeing any actual software code other than that ever-present“http://www…”, which is itself one of the key standards that enable the World Wide Web.
One of the interfaces defined by the OGC Web Map Service (WMS) Standard is
GetMap, an interface to obtain a simple map image in a common image format (PNG,
JPEG, PPM, or TIFF) that can be displayed easily on a website or inserted into adocument. A standard Web browser can ask any developer's OGC compliant Web Map
Service to provide a map simply by submitting a WMS request in the form of a URL(Uniform Resource Locator, a W3C standard, well known because of the public visibilityof a URL’s http:// prefix.). Here is a GetMap request for a particular AVHRR(Advanced Very High Resolution Radiometer) image:
http://a-map-co.com/mapserver.cgi?VERSION=1.2.0&
REQUEST=GetMap&CRS=CRS:4326&BBOX=-97.105,24.913,78.794,36.358&WIDTH=560&HEIGHT=350&LAYERS=AVHRR-0927&STYLES=&FORMAT=image/png&EXCEPTIONS=INIMAGE“BBOX” is one of 11 parameters in this request. The OGC WMS standard tells
programmers that, in a WMS map request, "BBOX" means "bounding box" and thatBBOX must be followed by "=" and then by two points (corners of the bounding box)
expressed as latitude/longitude coordinate pairs. The WMS standard answers
programmers’ questions such as: Which corners of the bounding box do these points
define? What's the order of the coordinate pair? Are those miles or kilometers? Will
integers work or must the numbers be floating point numbers?
The WMS standard "captures consensus" on such questions. The world's interested
geospatial software experts agreed in OGC's consensus process that this is how a Webbased map request should work. As in all software programs, programmers need to getmany small details exactly right. If the client request correctly implements the WMS

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standard, and if the server correctly implements the standard, the client will get a map
from the server and display it.
The OGC WMS Compliance Test tests implementations of the OGC WMS Standard toensure that the implementers got all the details right.

Compliance testing program documentation
The Compliance Testing document on the OGC website (available as a pdf filedownloadable from http://portal.opengeospatial.org/files/?artifact_id=7586) describes the
OGC Compliance Testing Program in detail. The document defines the approach,including policies and procedures that the OGC uses for compliance testing of serverside implementations of specific OGC standards.
After the developer obtains the trademark license, when a visitor to the OGC website’s
Products page (http://www.opengeospatial.org/resource/products) moves the cursor
over the product name, a “Certified OGC Compliant” service mark appears. This service
mark indicates that compliance with a particular OGC standard has been achieved, andthis service mark provides an incentive for potential customers to preferentially purchasesuch products.
A fully executed OGC Trademark License Agreement, fully paid trademark license fees,
and full compliance with the Trademark License Agreement terms are mandatory for an
organization to use the "Certified OGC Compliant" mark with its product(s) in any way or
to claim "compliance" with OGC Implementation Standards.
There are currently hundreds of organizations worldwide who use the “Certified OGC
Compliant service mark as an integral part of their product marketing.

Trademark Licensing Fees
The OGC does not charge a fee for compliance testing under the Testing Procedure.
The OGC does charge a fee for trademark licensing for Candidate Products thatsuccessfully pass a compliance test under the Testing Procedure; this fee is called theTrademark Licensing Fee. This fee must be paid by providers that want to claim
compliance with OGC Implementation Standards. This fee is not required to initiate andcomplete a test. The current fee structure is available at
http://www.opengeospatial.org/compliance#trademark.
The governing information for Trademark Licensing Fees is available at
http://www.opengeospatial.org/ogc/policies/trademark.

Caveats
ICT standards are the backbone of the ICT industry, but they are usually complex andneed time to mature. OGC standards have matured to the point where they are widely
implemented and largely uncontested as the standards that developers employ to build
systems that can exchange geospatial data and geoprocessing commands with othersystems. But compliance testing is also complex and takes time to mature. We list below
a number of issues regarding compliance testing, because we believe that increased
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understanding of OGC’s compliance testing program, including an understanding of its
limitations, will lead to more participation in the program and more demand for the
Certified OGC Compliant service mark. The following are existing caveats as of
September 2010.
•

OGC compliance tests are available for some but not all OGC standards. The OGC
is continually enhancing and expanding the Compliance Testing Program, and we
encourage interested organizations to participate in this effort. If a software productincludes an interface (or if a data product is based on an encoding) that implementsa specific OGC standard, but the product has not passed a compliance test (perhaps
because no test is yet available), the product's developer can label the product as"implementing" a specific OGC standard. For example: "This product implements the
OGC Geography Markup Language (GML) Standard, version 2.1." The developer
may also say: "This product will be submitted to OGC for compliance testing."•

Compliance testing addresses the degree to which a product has properly
implemented the standard. Compliance testing does not ensure or test fullinteroperability between different software products. Applications that use compliant
interfaces and encodings usually interoperate well. As a standard matures and as
more organizations contribute requirements, comments and expertise, noninteroperability problems become less common. In the OGC, new compliance tests
are constantly being developed, and the testing program continues to evolve to meetthe needs of industry.

•

OGC is exploring the next level of compliance – interoperability certification. The firststep of this process is the conduct of plugfests where developers are invited to test
their OGC Certified Compliant products with other certified products. OGC
anticipates formalizing interoperability certification in the near future.

•

Currently the CITE program only tests server products. In other words, the program
can only test whether server products generate compliant responses to client-side
products. The program does not presently offer capability to test compliance of clientside products, although this capability is being considered for future compliancetesting.

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