INTRODUCTION
Currently, the Geographic Information Systems (GIS) have succeeded in extending its practical utility including users with different levels of training, due to the rise of web applications, increasingly focused on the end user and with graphical interfaces enriched. The purpose of this study is to provide decision elements to web GIS projects analysts to choose one or other client side technology, according to the requirements of a particular project.
The web mapping clients are internet applications that allow to visualize and manipulate geographic information by means of basic tools of navigation and analysis. There are several free and open source software (FOSS) that make easier the management, development and customization of these sort of applications, which consume web services and communicate the user with advanced tasks to be performed on the server.
The Open Geospatial Consortium (OGC) has promoted the use of standards for web map services which have helped to establish a common framework to spatial data access in the internet (Web Map Service, Web Feature Service, Web Coverage Service), to present it by means of styles (Style Layer Descriptor), to filter it (Filter encoding), to store it, to transport it (Geography Markup Language and Keyhole Markup Language) and to process it (Web Processing Service).
DEPENDENCE BETWEEN CLIENTS
Below is a graph of dependence 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 features that this client provides: map scale, map reference, basic navigation tools, identification of geographic objects and their Application Programming Interface (API) called MapScript which has been implemented in different programming languages like PHP, Python, Java, Perl and Ruby, and continues its development by adding features such as advanced labeling and generation of bar and pie graphs. On the other hand, the new generation of clients uses OpenLayers due to its optimal performance in rendering tasks on the web. Different companies contributes to its development and projects like MapBuilder have ended to accelerate its progress.
There are clients that are not based on others but have been originated independently, as the case of Geomajas, iGeoPortal, Mapbender, TimeMap, MiraMon, Geoide and worldKit. Some clients use optionally 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 that use Flash for building Rich Internet Applications (RIAs) such as Flamingo, worldKit, OpenScales and Geoide, providing a new experience for users looking to view maps online.
THE COMPARISON
The comparison is based on free and open source projects with ability to access web services regulated by the OGC, showing in the form of advantages and disadvantages different parameters such as: license, country of origin, internationalization, commercial support, programming languages supported, its independence with respect to map servers programs and its metadata management, among others.
The comparison is presented in three parts to facilitate the visualization:
1. General description: Gives an introduction about each project.
2. Technical features: Presents technical data of the programs to facilitate a detail description.
3. Links of interest: Includes a screenshot showing the interface for each client and links for accessing pages of the same.
CONVENTIONS: Advantage, Disadvantage.
Client officially abandoned.
Client without recent version (over a year without a new version).
WHAT'S NEW IN THIS VERSION?
- The following clients have been added: Dracones, FlexLayers, HSLayers, kvwmap, MapFaces, OpenScales y Geoide (thanks to Herman Assink, who proposed it).
- The data the other clients was updated.
- The parameter "Support of tile-based maps" was added to distinguish the clients with the ability to load tiles.
- A new link was added for each project: Functionalities or a roadmap.
- Small images were included for some clients to show if they have been officially abandoned or they do not have a recent version.
- Most of acronyms were described using HTML to make the reading easier.
- The parameter "Map server dependence" was deleted because of its ambiguity.
SUGGESTION: Please avoid to use IE6 or IE7 to see the comparison, it seems the css support does not work as expected, you can use instead a browser like Mozilla Firefox, SeaMonkey, Opera or K-Meleon, in which the correct diagramming of the tables has been proved.
| [1] BSD compatible. [2] GPL compatible. [3] See: http://www.mapserver.org/copyright.html#license [4] Very quickly support from USA, Netherlands, Brazil and Italy. [5] Developed by Martin Hűgh. [6] City of Saint Paul, Minnesota. [7] Developed by Xavier Pons. [8] Developed by Armin Burger. [9] Incomplete documentation. [10] The only available documentation is related to the installation process. [11] The user interface is in spanish and in latvian as well. [12] Incipient documentation. [13] Currently there are translations to several languages: swedish, spanish, bulgarian, pole, italian, french, czech and slovene, among others. [14] OSGeo doesn't support it as an official project, but hosts their mailing list and Trac. [15] The copyright will be transferred to OSGeo. [16] There is an incubator application since 2007, but the answer is unknown. More information: http://trac.osgeo.org/osgeo/ticket/147 |
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| [1] When MapGuide Open Source is present, Fusion is able to use a PHP API. [2] The WFS only works for points. [3] Supports the GetCapabilities, GetFeatureOfInterest and GetObservation requests of the SOS specification. [4] As a server supports additionally the WCS and SOS services. [5] Takes this feature from OpenLayers. [6] In the last version was introduced an example with OSM but with no tiles. [7] Supports a large number of map sources based on tiles. [8] It only supports the TMS Global Geodetic profile. [9] Runs through a Java applet. [10] Camptocamp SA has added support for the GetDomain and GetRecords requests of the CSW specification to OpenLayers. [11] It has a search component that uses either a thesaurus or the CSW specification. [12] The HS – RS company offers it as a component of its solution for geoportals. [13] Currently there is a proposal to build a metadata catalogue client using GeoNetwork. (See: https://trac.mapfish.org/trac/mapfish/wiki/Proposals/Catalogue and http://www.camptocamp.com/fr/blog/2009/06/732/) [14] Supports the GetDomain and GetRecords requests of the CSW specification. [15] They will be available in a couple of months. [16] It has a mailing list for users and developers. [17] It does not have its own mailing lists, they are from the Deegree project. [18] It has mailing lists for: Users, developers, commits, announcements, tilecache and trac, among others. [19] There is a Google group for developers. [20] It has a mailing list in german. |
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NOTES ABOUT THE COMPARISON:
- The data for the new clients were collected directly from their websites, then validated through mailing list. Validation and some suggestions were received from all the new projects except FlexLayers, because it is abandoned.
- The empty cells indicate that it was not possible to obtain information.
- OSGeo support is given when the project graduates of the incubation process, so the projects that are in the incubator are not OSGeo official projects and do not receive the support. (See: http://www.osgeo.org/node/343 )
I appreciate the 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, and by Paolo Cavallini from Faunalia, which have enriched the comparison.
Due to the constant innovation and implementation of technologies in this type of projects, I expect to keep the comparison updated every six (6) months.
You can collaborate
If you see 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 add it.
LICENSE
This article is under license "Attribution 2.5 Colombia", watch it in this link: http://creativecommons.org/licenses/by/2.5/co/deed.en
CONCLUSION
There is plenty of FOSS projects to build web mapping clients, some of them allow a comprehensive management of information and receive support from OSGeo because they involve efficiently a whole community, whereas others are result of individual efforts that satisfy basic requirements. Some have been disappearing because of duplicated efforts whereas others have been based on previous developments to expand its functional scopes.
REFERENCES
- 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 on: http://www.smartmapbrowsing.org/html/index_en.html
- Open Source Geospatial Foundation (OSGeo). Official website: http://osgeo.org
- CSS Styles for tables: http://icant.co.uk/csstablegallery/index.php
- Flags of the world: http://www.33ff.com
comments
I've got some notes for you about GeoMoose that you may not be aware of, also a couple of corrections in a couple of spots. Just Email me and I'll send them along.
bobb (AKA blammo)
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