Introduction

The OGC Process

The OGC exists to enable a fast, effective, inclusive, user-driven process to develop, test, demonstrate, and promote the use of geospatial information and services by using OpenGIS® Standards.

The OGC has defined the standards around different GIS cloud services by following the process of identifying and addressing existing problems in the GIS industry. The process is:

1. Identify the Problem
2. Craft a Solution
3. Evaluate the Proposed Solution
4. Implement Standards

One of the major problems identified and addressed is interoperability. The following topics have been discussed and prioritized as part of identifying and addressing the interoperability problem:

• Sharing maps on the Web
• Delivering data to different systems easily
• Deriving a common language to speak about geospatial data or services
• Finding and pulling together data from our automated sensors

Details About Interoperability

Interoperability at a technical level refers to the ability for a system or components of a system to provide information portability and inter-application as well as cooperative process control. Interoperability comprises intercommunication at communication level protocol, hardware, software, and data compatibility layers.

Interoperability, in the context of the OpenGIS Specification Program, is software components operating reciprocally to overcome tedious batch conversion tasks, import/export obstacles, and distributed resource access barriers imposed by heterogeneous processing environments and heterogeneous data.

Interoperability with respect to geoprocessing refers to the ability of digital systems to 1) freely exchange all kinds of spatial information and 2) cooperatively, over networks, run software capable of manipulating such information.

Organizations and companies have been providing online mapping services for years. These Web mapping systems have been implemented as a set of proprietary systems. As a result of this isolated development, online mapping services from different vendors are not interoperable. Thus, many technology islands are created and preserved, and many users are locked into single-vendor solutions. This situation is slowly improving but, unfortunately, most Web mapping applications today are still inseparably tied to a specific server implementation. In other words, the Web client is hard-coded to interact with a particular vendor's proprietary map server implementation.

Figure 2.1 shows a scenario where the user must run three different Web applications in order to access the data and functionality provided by three different server implementations. In this scenario, there is very little interoperability or reuse of the Web client and server implementations.

Only Web Client-1 allows access to more than one database. Unfortunately, Web Client-1 may not provide all the functionality that Web Client-2 and Web Client33 offer. Even with Web Client-1's ability to access data of interest from multiple databases, the user must still run three different applications from the different Web clients to perform a given task.

Interoperability

To address this problem, the OGC developed a non-proprietary Web mapping approach based on open interfaces, encodings and schemas. The OGC Specification Program and Interoperability Program provide an industry consensus process to plan, develop, review and officially adopt OpenGIS Specifications for interfaces, encodings and schemas that enable interoperable geoprocessing services, data, and applications.

With standards-based interoperable Web mapping, each map server implements a common interface, a messaging protocol such as the WMS interface for accepting requests and returning responses. Now, the same client has Web access to potentially all available map servers and multiple data sources, where each map server is accessed by a client through the common interface.

This approach allows, among other things, a way for the user to run a single client that accesses all the capabilities of each server. This allows a more open application environment where the best features of available Web services can be flexibly combined in innovative and previously unimagined ways to solve novel and increasingly complex problems.

Interoperable Distributed Mapping

OGC Standards and Specifications

OGC® Standards and Specifications are technical documents that detail interfaces or encodings. Software developers use these documents to build support for interfaces or encodings into their products and services. These specifications are the main "products" of the Open Geospatial Consortium and have been developed by the membership to address specific interoperability challenges. The OGC documents are offered at no cost and are available to everyone.

OGC Reference Model (ORM)

The OGC Reference Model (ORM) provides a framework for the ongoing work of the OGC. The ORM describes the OGC Standards Baseline (SB) focusing on the relationships between the OpenGIS Specification documents. The OGC SB consists of the approved OGC Abstract and Implementation Specifications as well as OGC Best Practices documents. Best Practices documents are official positions of the OGC members and are often provided as supporting technical information for the adopted Specifications.

The ORM has the following advantages and purposes:

• Provides an overview of OGC Standards Baseline
• Provides insight into the current state of the work of the OGC
• Serves as a basis for coordination and understanding of the documents in OGC SB
• Provides a useful resource for defining architectures for specific applications