Summer 2012 Edition
By Richard Kachelriess, Esri Product Marketing
It's a deceptively simple question. Open is a term that's thrown around in the GIS industry and in the technology industry in general: open systems, open source, open standards, open specifications. This can quickly become confusing. Fortunately, every variation on the open theme can be placed into one of three categories: open source, open data, or open systems. Hopefully, this article will clear up some of that confusion by explaining the differences of these open technologies, how they combine into the open technology approach, and how they relate to ArcGIS.
Open source software is just that—software. The only difference between open and closed (or proprietary) source software is that with open source, the code used to create the program is freely available for anyone to view, edit, and redistribute. Any type of software can be open source software. The type of license under which it is released determines if it is open source. Examples of open source licenses include the Apache 2.0 license, the Microsoft Public license, and the GNU General Public license.
Esri continues to increase its participation in the open source community with several open source products. Adding to Esri Geoportal Server and ArcGIS Editor for OpenStreetMap, Esri has made ArcGIS Viewer for Flex open source. The source code is now available on GitHub. Additionally, Esri is planning to release the source code for the ArcGIS for iOS and ArcGIS for Android mobile applications soon.
Open data is information that is freely available for anyone to use and reuse. Data is completely open if there are no restrictions on its use for public, private, nonprofit research, or commercial applications. OpenStreetMap is the quintessential open data GIS project. Its goal is the creation of a free, editable map of the entire world. The data from this project is available under the Creative Commons Attribution-ShareAlike 2.0 license that allows users to copy, edit, adapt, and transmit that data for any reason as long as OpenStreetMap is credited. Any edits can be redistributed under the same license. Many organizations use OpenStreetMap. While most organizations use it as a free basemap, a growing number of companies are building commercial solutions on top of OpenStreetMap data.
Just because data is open doesn't mean that it is easily accessible. Open data can still be stored in formats that are proprietary or rarely used and can be difficult to access. To be truly beneficial, open data should be stored using an open or established specification, such as shapefiles or file geodatabase specifications, or be accessible via an open or established standard service, such as the ArcGIS map service definition, Web Map Service (WMS), or Web Feature Service (WFS).
Standards and specifications are technologies, models, and procedures that help establish interoperability between programs, devices, and systems. They include file types and web services. In an open standard or specification, the information to create, modify, and interact with these formats and services is freely available for anyone to use, edit, and redistribute. This allows organizations to integrate these formats and services into their applications. Without established standards, interoperability between systems would be impossible.
The difference between open standards and open specifications is vague at best. Generally, an open standard is an open specification that allows users complete freedom in its use: they can read, create, edit, and transmit data using the specification as well as modify or redistribute the specification itself. While an open specification generally allows users to read, create, edit, and transmit data via the specification, it often does not allow them to modify or redistribute the specification.
The Open Geospatial Consortium, Inc. (OGC), is an international organization for developing and governing open standards for geospatial data, services, processes, and data sharing. Esri is a principal member of OGC and actively participates in the development and implementation of many of these standards.
Systems, also known as platforms, bring together software, data, and standards into one package to help solve problems and make decisions. Open systems are systems that easily connect to and integrate with external systems. A web browser application is an open platform. It can connect to and integrate with external applications and systems by using established standards such as TCP/IP protocols and HTML. Open standards and specifications are critical to the success of the Internet. The web browser can be closed source, and the data can be proprietary, but if the system uses established standards and specifications, it would be an open system.
The open technology approach means using the best combination of open source software, open data, and open standards and specifications with proprietary source software, data, and standards and specifications to build the best open system possible. This hybrid approach allows systems to be built that best fit specific needs and workflows.
ArcGIS is an open system. It works on a wide variety of operating systems and external software programs and technologies. ArcGIS is designed and engineered with interoperability and extensibility in mind and conforms to the open standards and specifications necessary to implement enterprise systems. This open technology approach allows ArcGIS to interact with CAD and raster data; geospatial files from third-party developers, such as ENVI EX; relational databases, such as Oracle, PostgreSQL, and SQL Server; and web services, such as WMS, WFS, and Web Coverage Service (WCS).
Esri's collection of developer tools also contributes to its open technology approach. ArcGIS Runtime is the latest product in Esri's line of developer solutions for creating and deploying focused, stand-alone GIS applications. It is a collection of GIS components and developer resources that allows GIS functionality, dynamic maps, and GIS capabilities to be embedded in existing applications or new custom ones to be built. ArcGIS Runtime allows users to build native applications for Java, Windows Presentation Foundation (WPF), Android, iOS, Windows Phone, and Windows Mobile. Technology like this allows Esri's partners to build custom solutions using the power of ArcGIS technology. For more information, visit esri.com/open.