BOLETÍN OFICIAL DEL ESTADO
MÓDULO FORMATIVO 4
This section describes some of the most widespread geographic information web services currently available.
UMN MapServer30is the most successful web service today. It is implemented
with C++ and it can be used as a web service, using CGI, and as a library
(supporting PHP, Python, Perl, Ruby, Java and C#). Although it has been
developed for Linux, it can also be used within Windows following a much more complex installation and configuration process. MapServer web service allows the developer to use all types of data sources: ESRI datasources such as shapefiles or ArcSDE, different DBMS such as Oracle, PostGIS, or MySQL, and many other
data formats using the GDAL/OGR library31. This library allows reading, and
sometimes writing, information in a large number of formats. MapServer supports
the main standards of geographic information: WMS (client and server), WMC32,
SLD33, WFS (non-transactional), Filter Encoding34, WCS35and GML36.
Geoserver37 has a big advantage versus the previous alternative: it is the easiest geographic information web service to install and configure. Geoserver is implemented with Java and it can be used as a web service through its J2EE application. It can be configured through its own user interface in a simple way. However, one drawback in this web service is its limited performance, as it is slower than other competitors.
GeoServer uses OpenLayers as integrated viewer for visualization of the geographic data within the tool itself, and additionally it allows to generate maps in many formats: Google Earth KML, PDF or SVG.
30http://mapserver.org/ 31http://www.gdal.org/ 32http://www.opengeospatial.org/standards/wmc 33http://www.opengeospatial.org/standards/sld 34http://www.opengeospatial.org/standards/filter 35http://www.opengeospatial.org/standards/wcs 36 http://www.opengeospatial.org/standards/gml 37http://geoserver.org/
4.4. GIS software 39
Geoserver can use different data sources with different levels of integration. Among the sources of data that we can consider mature are the DBMS PostGIS, Oracle, DB2, ArcSDE or Shapefile formats. It also supports other WFS, MapInfo, or MySQL data sources. This service supports, like the previous one, most of the standards for the interoperability and communication of geographic information, including WMS, SLD, WFS, Filter Encoding, WCS and GML.
Deegree38 is probably the most complete web service discussed here. It is developed with Java and it can be used as a web service through its J2EE application. The main problem of Deegree is the complex configuration, in addition to having worse documentation than other tools. However, this web service provides good
performance and it is the one tool supporting more OGC standards. Deegree
includes its own GeoPortal. Data sources supported by Deegree include all types of DBMS (PostGIS, Oracle, and others such as SQL Server or DB2 that can be supported as generic SQL) as well as ESRI data sources (ArcSDE and Shapefile).
As we have already indicated, Deegree supports a multitude of standards. Like the previous ones, it supports WMS and SLD, WFS (transactional) and Filter Encoding, WCS or GML. It also provides functionalities in accordance with other
standards: catalogues according to the CSW standard39, interactions according to
the Web Processing Service (WPS40) protocol.
MapGuide41 is a tool released by Autodesk as open source software. This tool is part of the commercial software of Autodesk, and is implemented with C++. It can be used as a web service using CGI or as a library in PHP, Java or .NET. MapGuide provides ready-to-use web clients. MapGuide supports access to data
using the FDO library42. This allows you to use ESRI formats such as Shapefile or
ArcSDE, MySQL, ODBC or GDAL / OGR formats as data sources. You can also use it as a WMS and WFS client. This web service supports the basic standards of OGC WMS and WFS.
TileCache43 is an implementation of a WMS-C performed by MetaCarta. It is implemented in Python and it can be used as a CGI web service. Instead of generating the image with each request to the WMS, TileCache stores a tile cache. In this way, for each zoom level, the cartography is rendered in advance as a set of cells. TileCache acts as a WMS-C service that can be used on clients that support this standard. 38http://www.deegree.org/ 39http://www.opengeospatial.org/standards/cat 40http://www.opengeospatial.org/standards/wps 41https://mapguide.osgeo.org/ 42 http://fdo.osgeo.org/ 43http://tilecache.org/
40 Chapter 4. GIS: state of the art
FeatureServer44 is a feature server developed by MetaCarta, just like Tile- Cache. It is also implemented in Python and can be used as a CGI web service. FeatureServer supports DBM, BerkeleyDB and PostGIS DBMS data sources. It can also function as a WFS service client, and you can use other OGR data sources (Shapefile, GML, etc.) or even Flickr images. This web service provides services based on different formats. It allows the use of JSON, GeoRSS or KML in different services for both input and output data. It also provides services for sending data in HTML, WFS (GML) or OpenStreetMap format.
GeoNetwork45is a metadata catalogue implemented in Java, and available as a web service in a J2EE application. It allows to manage and publish metadata of the spatial data infrastructure. GeoNetwork can use data sources based on ISO 19115
and 19139 metadata standards [fSe,fSk]. It also supports FGDC standards [Com],
used in the United States, or the Dublin Core standard [KB07]. This server
provides catalogues compatible with the OGC CSW standard, specific for the availability of metadata catalogues. It also supports the OpenSearch standards (for the provision of search results) and the Open Archives Initiative standard for
content interoperability on the Web [LdS01].