Home Articles deegree – Components and Framework for SDI

deegree – Components and Framework for SDI

Dr. Markus Lupp
lat/lon, Kupang, Timor, Indonesia
[email protected]

deegree is a Java-based Open Source / Free Software framework for the implementation of Spatial Data Infrastructures. It contains the services needed for SDI (deegree Web Services) as well as portal components (deegree iGeoPortal), mechanisms for handling security and access control issues (deegree iGeoSecurity) and storage / visualization of 3D geodata (deegree iGeo3D).

deegree is based on the standards of the OGC and ISO / TC 211. Presently it is the most comprehensive implementation of those standards in one Open Source framework. The framework is component-based to a high degree, allowing the flexible creation of solutions for a wide variety of use cases. It is published under the GNU LGPL.

COMPONENTS
deegree comprises five groups of components that are briefly described in the following.

DEEGREE WEB SERVICES
These are the base components of any SDI. The list of implemented OGC Web Services includes WMS, WFS, WCS, CSW, Gazetteer, SOS, WPS and WTS/ WPVS. Besides, two security services (WAS/WSS), a printing service (WMPS) and a service monitor (owsWatch) are available.

DEEGREE IGEOPORTAL
iGeoPortal has a modular structure and is able to display maps, support searches using geographic identifiers, search for datasets using metadata, allow for controlled access to OGC Web Services and display of 3D geodata.

deegree iGeoPortal itself consists of different modules for separate, but combinable, functionalities. The list of modules includes: map, download, gazetteer, catalogue, security and 3D.

DEEGREE IGEOSECURITY
deegree iGeoSecurity can be used to define access mechanisms using authentication & authorization mechanisms, secure connections and filtering of geodata. A database for managing users, user groups, roles and rights called deegree U3R is the core component of the security components.

DEEGREE IGEO3D

deegree can be used to store 3D geodata such as digital terrain and building models in file-based systems and relational databases. Using different deegree web services, this data can be queried and displayed.

DEEJUMP
Using deegree components, the Open Source desktop GIS OpenJUMP (Java Unified Mapping Platform) was enhanced to support WMS and WFS. A number of additional modifications and extensions was also developed.

OVERALL ARCHITECTURE
The different deegree components can be combined with each other or with other standard-compliant software. iGeoPortal with its different modules

Open Source
CityGML A GML application schema for city models CS-W Catalogue Service – Web. An OGC standard for access to metadata GML Geopraphy Markup Language. An OGC standard for XMLbased encoding of geospatial data.

GNU LGPL
The library or lesser GNU public License. A Free Software license developed by the Free Software Foundation (https://www.fsf.org) OGC The Open Geospatial Consortium, an international standardization consortium for geospatial applications.

OWS OGC Web Services
SDI Spatial Data Infrastructure

SLD Styled Layer Descriptor. An XML grammar for styling information. In version 1.1.0 SLD is split into Symbology Encoding and SLD.

SOS Sensor Observation Service. A standard of the OGC for access to time-dependent sensor data U3R User Rights, Roles and Resources. A database schema used by deegree for storing access control information.

WCS Web Map Service. A standard of the OGC for data access (mainly raster data).

WFS Web Feature Service: A standard of the OGC for data access (vector data) WFS-G Web Feature Service – Gazetteer profile. A WFS specialized on placenames and addresses.

WMS Web Map Service. A standard of the OGC for data visualization. WPS Web Processing standard. A standard of the OGC describing a service able to process geospatial data.

WTS
Web Terrain Service. A standard by the OGC describing access to 3D visualizations using pictures. Newer version of thes specification are sometimes called Web Perspective View Service (WPVS).

XPlanGML A (German) GML application schema for urban and town planning information. acts as a web-based client to the different Web Services. Alternatively, dee- JUMP can be used to access WMS oder WFS services. If needed, security management can be implemented using iGeoSecurity. deegree can access different data sources, e.g. PostgreSQL /Post- GIS or Oracle databases, shapefiles, all kinds of relational databases using a deegree-specific spatial extension and different kinds of image formats such as PNG, GIF, JPEG or (Geo)TIFF.

APPLICATION AREAS
deegree technology can be used in all areas that benefit from SDI approaches. The three major application areas for deegree in the future will be urban and town planning, environmental information systems and natural disaster management, in more detail described in the following.

URBAN AND TOWN PLANNING
The processes of urban and town planning require integration of a variety of data sources as well as the distribution of planning information to a wide audience. Integration of data is possible using two methods, one being the usage of raster information that still is the rule, although much information is lost this way. The second method is the exchange of object-structured information that is theoretically superior but in practical projects still the exception. Distribution of the information can best be done using the Web, therefore application of geoportals and corresponding standards like WMS and WFS seem necessary. A number of deegreebased projects in Germany and the Netherlands address these issues.

Major problems were identified regarding the integration of data while applying the approaches described above. While raster integration seems technically unproblematic, existing data often does not satisfy basic requirement like proper georeferencing or common application of styling rules.

While an object-oriented approach seems much more satisfying and standards like GML are by now able to scope with the necessary complexity, the practical problems here are still hard to overcome. Using deegree a prototype implementation of an object-model (XPlanGML) based planning information system was developed under the name XPlanung Publishing Platform. In the future, the development and application of object models for planning purposes and the coupling of 2D data with 3D city models will be major themes handled by deegree.

ENVIRONMENTAL INFORMATION SYSTEMS
Almost all environmental information is geospatial information and can best be analyzed when displayed together with other georefenced data. Although environmental information systems include additional aspects ,they benefit greatly from an SDI approach. SDI allows integration of distributed data

PROJECT DESCRIPTION
Vietnam is the destination for the new century and Ho Chi Minh City is the biggest city in Vietnam. Because of its fast growth, tourists and explorers will find this website useful. There is a detailed map of Ho Chi Minh City with streets, land marks, rivers, buildings, hotels It’s possible, if you have an account, to bookmark your own points of interest on this map. There is also statistical information about the administrative unit of Ho Chi Minh City including population, area, education and other things. (Text taken from . org/pressroom/newsletters)

What is MIDAS?
MIDAS is a ‘one-stop shop’ for companies and online services needing easy and efficient online access to weather information.

What MIDAS Does
MIDAS provides online access to a rich set of dynamic weather forecast, satellite nowcast and marine environmental information for easy real-time integration into third-party end-user applications and web services. MIDAS provides two simple to use IP-based APIs to support the inclusion of its content: (i) a simple HTTP-based OGC-compliant interface, and (ii) an XML-based interface supporting more complex data retrieval requests.

ProSiN
The planning portal of Hamburg offers the public information about planning data – both the current legally binding development plans which can be downloaded as PDF files as well as development plans being still in process. The portal is based on WMS, WFS-G and WMC standards. The citizen can navigate via a gazetteer enabling a search via street and house number. The next step is the integration of participation module based on WFS.

o – dimaed s cess ed zabof View sources, their analysis and display. deegree- based systems can be coupled with tools such as iReport to handle environmental reporting tasks.

DISASTER AND RISK MANAGEMENT
The application SDI this technology to disaster management poses several challenges, the two most important being reliability of the overall system and integration of up-to-date sensor information. An approach to this is under development in a joint German- Turkish research project called EDIM (Earthquake Disaster Information System for the Marmara Region, Turkey), funded by the German Federal Ministry for Education and Research. The architecture of the system is based on standards developed by the OGC e.g. WMS, WFS and SOS. The software components used in the project will mainly be taken from deegree, so that transfer of project results to other regions with similar disasters will be easy and costeffective. Transferability and fail-proof strategies and dynamic integration of sensor data linked to cartographic display will be cornerstones of the project.

PROFESSIONAL SERVICES
deegree is a commercial Open Source project in the sense that lat/lon bases its business model mainly on services about deegree. Although a number of other institutions are contributing to the deegree project, the majority of its development still is done as part of lat/lon’s projects. The services offered by lat/lon include development of project solutions, consulting and coaching for institutions using deegree and support of businesses who want to develop solutions and products using deegree.

CURRENT STATUS
In June 2007 deegree day took place in Bonn Germany. At the same time, the 2.1 releases of deegree were published. The corresponding demo releases are extremely easy to install as they come as WAR-archives and can be deployed within seconds if a Tomcat Servlet engine is available. The demo releases include a WMS, a W Fs (with gazetteer), a WCS, a Catalogue Service-Web (for ISO metadata), a WTS. All demo releases come with preconfigured data sources and detailed documentation. The release 2.1 is a major step forward in deegree’s development. Visit https://www.deegree.org for news regarding deegree day 2007 and deegree releases.