Summary: How confident are you in your knowledge of open source geospatial software? How about a quick introduction or refresher? Executive Editor Adena Schutzberg offers 10 points that are important to understand about open source software.
1) Open Source Geospatial Software
Open source geospatial software refers to GIS, GPS, spatial data management and related developer tools and end user applications delivered with an open source license.
Some people use the term FOSS4G, meaning Free and Open Source Software for Geospatial, to describe this set of software. FOSS4G is the name of an event hosted by the Open Source Geospatial Foundation (OSGeo, more on this organization in #6 below).
2) Open Source Licensing
An open source license must meet the definition developed by the Open Source Initiative. This non-profit corporation details the 10 criteria in a very readable document. Two of the criteria are:
- free redistribution of the software
- inclusion of its source code
Licenses that comply with the definition are listed on the website. Software packages, libraries and other code distributed under these licenses are accurately described as open source. Some software products are free to download and freely distributed but not open source. For example, Google Earth, while free of charge for non-commercial use, is not open source because it is not distributed under an open source license.
3) Open Source Software is Written by a Community
Open source software is written by a community rather than a development team associated with a single software company. Participants from all over the world contribute via the Web. Some do this as part of their “day jobs,” while others volunteer.
A project steering committee or other group keeps order and manages contributions, bug lists and source control. Because the source is available, changes to a local implementation can be made immediately, though changes to the accepted current version may take time to be incorporated.
4) The Opposite of Open Source is Closed Source or Proprietary Software, not Commercial Software
Open source software is (among other things noted in the definition cited above) delivered with its source code. Closed source (aka proprietary) software does not necessarily provide source code, though it can. That does not make it open source; to be open source it must meet all the criteria and carry an approved license.
Both closed source (proprietary) software and open source software are commercial software. That is, they can both be used to make money. Open source providers offer services (such as training, installation and customization) or related software (installation packages, tutorials, etc.).
5) Open Source Software is “Just” Software
Open source software shares quite a lot with closed source software. Both can be buggy or stable, have a slick user interface or a clunky one, be well documented or poorly documented, be easy to use or difficult to use. Nothing about the development, licensing, distribution or cost of the software necessarily makes open source stronger or weaker on any of these criteria.
That said, open source advocates suggest that programmers are more diligent if they know the world will be seeing their code. They also suggest that open source innovations can proliferate more quickly among both open source and closed source packages.
6) OSGeo is the Body for Open Source Geospatial Software
Modeled after the Apache Foundation, the Open Source Geospatial Foundation (OSGeo), which dates back to 2005, “was created to support the collaborative development of open source geospatial software, and promote its widespread use.” It helps organize, manage and incubate selected FOSS4G projects (found on its homepage). Many open source geospatial projects also live and thrive outside of OSGeo.
7) Open Source and Open Standards-based Software are not the Same Thing
Open source geospatial software must be distributed under an open source license. Open standards-based geospatial software packages/projects implement one or more open standards (such as those from the Open Geospatial Consortium or the World Wide Web Consortium) but can be distributed under any type of license. That said, many open source geospatial projects work hard to implement standards to ensure the software can interoperate with proprietary packages and data types. OSGeo includes support of open standards as one of its goals. However, some confusion exists because the terms are similar, but as noted, they are distinctly different.
8) Implementing Open Source Software May Cost Money
Open source software is distributed for free. Just like some proprietary software, it can be acquired, installed and used easily (e.g., Angry Birds), or it may require specialized consulting (e.g., SAP). An individual may be able to install, learn and use Quantum GIS (QGIS, an open sourced desktop GIS with a short learning curve), but an organization may need weeks or months of consulting to implement an enterprise GIS built on GeoServer, PostGIS and OpenLayers. Again, open source software is “just” software.
9) Mixing and Matching Open Source and Proprietary Software
Software developers and software users mix and match open source and proprietary software all the time. Esri’s ArcGIS, for example, includes the open source GDAL (raster handling) library. The license for GDAL, X/MIT, allows it to be embedded in other products.
Some Web mapping apps (CrowdMap, for one) tap into Google’s proprietary Google Maps API but render the results via open source MapLayers. Open APIs and support for open standards technically enable hybrid solutions, while carefully thought-out licenses make them legal.
10) Geodata and Open Source Licensing Don’t Mix
Open source licenses are designed for software, not data. There are other licenses appropriate for data. For example, the OpenStreetMap Foundation has been moving from a Creative Commons license (a license for creative works) to the Open Database License, ODBL.
Special thanks to Peter Batty for reviewing this article for accuracy.