Nowadays, Geographic Information Systems (GIS) have succeeded in extending its practicality by including users with different training levels, due to the rise of web applications, increasingly focused on the end user and with enriched graphical interfaces. The purpose of this study is to provide decision elements to web GIS project analysts for choosing a client-side technology, according to the requirements of a particular project.
Web mapping clients are pieces of software (applications, libraries, frameworks) that either provide or extend a web-based mapping component to view and interact with maps from remote sources on the Internet. There are several Free and Open Source Software (FOSS) projects that make development, customization and management easier for these sorts of applications. Some of them use pure client-side technology whereas the vast majority rely on server-side features allowing advanced tasks to be performed. Such tasks involve security matters, user and group administration, advanced printing capabilities, spatial analysis support and customization of graphic user interface items and functionalities, among others.
This comparison deals with all of these projects from a basic perspective, as web clients that allow standard geographic data to be accessed and viewed. The Open Geospatial Consortium (OGC) has promoted the use of standards for web map services, which have helped to establish a common framework to access and display spatial data on the Internet (Web Map Service, Web Feature Service, Web Coverage Service), discover it (Catalog Service for the Web), present it by means of styles (Style Layer Descriptor), filter it (Filter encoding), store it, transport it (Geography Markup Language and Keyhole Markup Language) and process it (Web Processing Service). The Web Map Service (WMS) and Web Feature Service (WFS) are the mainly used services for web mapping purposes, therefore, support for one of them is a must for a client to be included here.
RELATION BETWEEN CLIENTS
Below is a graph showing the relation between FOSS web mapping clients.
Most projects revolve around two paradigms: UMN MapServer and OpenLayers. Clients using UMN MapServer as a basis were created years ago taking advantage of the features that this client provides: map scale, map reference, basic navigation tools, identification of geographic objects and its Application Programming Interface (API) called MapScript, which has been implemented in different programming languages such as PHP, Python, Java, Perl and Ruby, and continues being improved by adding features such as advanced labeling and bar and pie graphs generation. On the other hand, the new generation of clients use OpenLayers due to its optimal performance in rendering tasks on the web and to the wide variety of data sources it supports. Different companies contribute to its development and projects like MapBuilder have ended to accelerate its progress, which have become it a state-of-the-art library for building web mapping applications.
There are clients who do not have relied on others but have been created independently, as the case of Geomajas, iGeoPortal, Mapbender, TimeMap, MiraMon, Geoide, worldKit and Flamingo. Some clients optionally use UMN MapServer by means of MapScript (AppForMap, GeoMOOSE and msCross) and others allow to choose an additional way to render their maps with OpenLayers (AppForMap, Mapbender and i3Geo) and Flamingo (i3Geo).
It should be noted that there is a growing number of projects using Flash/Flex for building Rich Internet Applications (RIAs) such as Flamingo, worldKit, OpenScales and Geoide, providing a new experience for users intending to interact with maps on-line.
The comparison is based on free and open source software projects with capability to access OGC web services, showing a variety of parameters such as: license, origin country, internationalization, commercial support, supported programming languages and metadata management, among others.
The comparison is presented in three parts to facilitate its reading:
- General description: Gives an introduction about each project.
- Technical features: Presents some technical data of each project.
- Links of interest: Includes a screenshot showing the client's Graphical User Interface (GUI) and links for accessing useful pages and live demonstrations.
CONVENTIONS: Advantage, Disadvantage.
Officially abandoned client.
Client without recent version (over a year without a new version).
WHAT IS NEW IN THIS VERSION
- Italian client GisClient added.
- Other client's data updated.
RECOMMENDATION: It is recommended to use a web browser such as Mozilla Firefox, SeaMonkey, Opera or K-Meleon, in which correct arrangement of the tables has been proved.
There is plenty of FOSS projects to build web mapping clients, some of them very professional allowing a comprehensive management of information and receiving support from OGC because they involve efficiently a whole community, others, result of individual efforts that satisfy basic needs. Some have been disappearing because of duplicated efforts and others have been based on previous developments to expand its functional scopes.
NOTES ABOUT THE COMPARISON:
- The GisClient data was collected directly from its website and then validated through its developers group.
- Empty cells indicate unknown information.
I appreciate suggestions made by members of the OSGeo local chapter of the Spanish speaking community (Capítulo Local de la comunidad hispanohablante de OSGeo), Jorge Sanz, Lorenzo Becchi and Evaristo Gestoso, by Paolo Cavallini from Faunalia and by the GeoTux user Mavka, which have enriched the comparison.
Due to the constant innovation in this kind of projects, I expect to keep the comparison updated every six (6) months.
You can collaborate
If you find out a mistake in the comparison, please let me know and I will fix it. If you know any other web mapping client and you would like to see it in the comparison, write me to study it and add it.
This article is under license "Attribution 2.5 Colombia", look it at: http://creativecommons.org/licenses/by/2.5/co/deed.en
- Official website of each project (See Part 3, Links of interest)
- Emanuel Schütze. Current state of technology and potential of smart map browsing in web browsers. Germany. June 2007. Available at: http://www.smartmapbrowsing.org/html/index_en.html
- Open Source Geospatial Foundation (OSGeo). Official website: http://osgeo.org
- CSS for tables: http://icant.co.uk/csstablegallery/index.php
- Flags of the world: http://www.33ff.com