Web based GIS as a Central Tool of an Information System for Interdisciplinary Research Projects C. Mückschel, C. Weist, and W. Köhler Biometry and Population Genetics, Justus-Liebig-University, 35392 Giessen, Germany, [email protected]

Abstract In heterogeneous working groups of interdisciplinary research projects a common data and information management forms the basis for integration and interconnectedness. Central data storage ensures consistent and efficient data management of the different disciplines. The data management must be able to represent adequately the research objects which are described by the data. Both timelines and spatial data must be presented and processed in environmental research projects which work on the ecosystemic level. Geographic information systems (GIS) proved of value for this purpose. Normally GIS applications are desktop specific and their use requires some expertise. The setup of a central Web-GIS in an interdisciplinary research project which can be accessed by a browser interface offers the advantage that even users with little or no experience with these systems can perform simple GIS based analysis. Scalable Web-GIS-approaches vary from the simple interactive presentation of maps to the implementation of models. They are of particular interest in the interdisciplinary research project ”Land use concepts for peripheral regions” (SFB 299) supported by the German Research Foundation (DFG). According to the tasks of the SFB and the ongoing development of information technology, the internet/intranet is becoming more and more important for the provision, transfer and analysis of geodata. Thus several GIS features are integrated and implemented in the existing web based information system. The information system is based on classic client/server-architecture. Several routine tasks of the data management are managed by the Open Source Content-Management-System (CMS) TYPO3. This has proved to be a good tool to improve effectively interdisciplinarity and exchange of research results in the SFB 299. This paper reports about the architecture with special consideration of the Web-GIScomponents, the implemented technique and the rationale underlying our information system. Keywords: Geodata Infrastructure, Data Management, Modular Information System, Client/ServerArchitecture, Typo3

1 Introduction Interdisciplinary research projects with environmental focus need information technology capable of describing the flow of minerals and other substances with respect to space and time. In many environmental studies, changes in the landscape can often be shown only via trend-analyses of time series. A suitable technology must also supply methods for processing of information in order to present project data and results in graphically as well as numerically meaningful ways. Geographical Information Systems (GIS) are the tools that meet these requirements best. In the DFG-Sonderforschungsbereich (SFB) 299, the Collaborative Research Center 299 (www.sfb299.de) of the German Research Foundation we implemented such web-based GIS successfully. These systems comprise at least two computers connected in a client/server-configuration. They

communicate through Internet technology, exchange geodata and offer GIS functionality. In the simplest case Web-GIS-technologies utilize static maps linked with graphics and HTML. All functionality must be designed explicitly on the server side. Any common web browser may serve as the client. More complex systems are based on distributed multi-user GIS. Proprietary Desktop-GIS software usually allows direct access via Internet protocols without the use of a web server. Especially Open-GIS standards as “Web Map Service” (WMS) or “Web Feature Service” (WFS) (OGC, 2007) are used in the development of Web-GIS-techniques. They facilitate the finding of highly portable solutions, which are mainly based on Open Source technologies. In this project several Web-GIS-systems are currently developed, ranging from tools for the simple depiction of maps to interactive connection of SFB-data with particular data of local users.

2 The SFB 299 information system Usually setting up an information system is less afflicted with difficulties and challenges than its permanent maintenance. For this reason information systems are mostly open systems which consist of different components and services (cf. Fig. 1). They offer a collection of comfortable query tools; especially concerning topical, temporal, spatial or context related aspects, whereas the query results can be presented in different ways. The SFB information system is based on WWW/Internet technology and is structured as distributed client/server-architecture. Data management in a closer sense is organized through the relational database management system (RDBMS) MySQL (http://dev.mysql.com/). The user interfaces access the data via Apache and Perl or PHP scripts. The scripts handle the data input and output, write notes, build record tables and thus are part of an expanded database management system. Structured metadata together with the described data are collected via web forms.

Fig.1 Modular composition of the SFB information system

One central component of the information system is Typo3 (http://typo3.org/). This is a content management framework based on PHP and MySQL and has a modular structure. Thus it is an appropriate completion since the existing database structures in the SFB have been realized with LAMP systems (Linux, Apache, MySQL, PHP/Perl) and different extensions. Significant advantages of this Open Source model are quality, scalability of the systems, high performance and stability (Altmann et al., 2004).

Typo3 is composed of two areas. The visible website is called frontend. It is accessed via a normal web browser. The main part of the SFB 299 website is accessible to the public. Typo3 supports the creation and management of frontend users. Thus an intranet service available to the co-workers operates as a project specific data and information platform with a bundle of features. On the intranet new publications can be entered via structured browser based masks. Furthermore SFB co-workers can input metadata which describe the primary data via consistent web forms. It is distinguished between meta information of documents, geo- point and other data. The search function of the meta database guarantees the clear listing of desired information, e.g. conditions of citation and use or creation methods of the scientific data in the SFB. In addition the metadata contain a link to the primary data. The management of the frontend users, the website maintenance as well as the whole database administration takes place in the so called backend. The backend is accessed via a web browser as well. The access rights vary depending on the role and working area of the respective co-worker. To use the extensive, spatial data of the SFB 299, a Web-GIS component was integrated into the information system which is linked to from the intranet area.

3 Web-GIS-components In the SFB nearly all datasets have got a spatial dimension. Spatial trends or processes can only be verified and analysed with GIS compatible tools. Visualization of the different data layers – e.g. land use data or climatic maps - is a first step of such analysis. Integration of GIS functionality into the internet based information systems offers the advantage of performing visualization or analysis without special software or software knowledge. The use of HTML and the graphical browser interface requires no special retrieval language. The browser based query is processed on the server side and is specified by the system administrator in conjunction with the SFB co-workers. 3.1 Composition of the geodata infra structure The core component of a Web-GIS capable geodata infrastructure (GDI) is a map server for the generation of dynamic map contents. In the SFB 299 there are mainly two approaches. First there is the use of the proprietary software ArcIMS of the ESRI company. Its advantage lies in a rather quick off the shelf setup and the system is ready for use straight away. ArcIMS supports the OGC compliant web mapping standard WMS. The high scalability of the system permits for a growing number of maps that can occur in the course of the project, which can be accessed by many users at the same time (ESRI, 2004). However the use of the software is dependent on the producer and is difficult to integrate individual functions. Furthermore viewer software needs to be installed on the client computers. The selection reaches from a simple HTML-viewer to a complex Java viewer with writing access and complex GIS functionality. In the latter case the Java 2 Runtime Environment has to be installed on client side for the execution of Java 2 applets (ESRI, 2004). SFB development focuses on an Open Source based architecture (cf. Kropla, 2005). On one hand there is a comparatively complex installation and the yet existing restrictions in terms of extensive GIS functionality; on the other hand there are numerous advantages. Besides low costs, especially the readily available Open Source code has to be mentioned. This allows a producer independent adaptation of the system according to changing requests in the course of the project. Also implementation of special functions and the creation of individual interfaces are not complex. Moreover, apart from a web browser the clients need no special software. Fig. 2 shows a schematical overview of the Web-GIS-components.

Fig.2 Schematical illustration of the Web-GIS-architecture

The shown geodata infrastructure is classical client/server-architecture. It consists of an Apache web server, the UMN MapServer (http://ms.gis.umn.edu), the server side scripting language PHP, the object relational database management system PostgreSQL (www.postgresql.org) including the spatial language extension PostGIS, the cartographic projections library Proj.4 and the geoportal solution Mapbender (www.mapbender.org), which forms the graphical user interface (GUI) with its browser based desktop. The UMN MapServer runs as CGI-program on the Apache web server. It is robust, stable, fulfils the standards of the Open GIS Consortium (OGC, 2007) and is under constant development through a large user community. Its task is to generate the maps requested by users. PHP function calls control the functionality of the UMN MapServer, which are forwarded to the map server by the dynamically loadable module PHP MapScript. The server side language PHP performs the interpretation of the PHP code as well as the connection to databases and networks. Its interpreter is not executed as CGI-program but runs as an Apache module. This leads to a better performance. The object relational database PostgreSQL serves as data server. Its spatial language extension PostGIS expands the database for geographical objects, supports common GIS analysis functions and permits spatial indexing of GIS objects. Essential advantages of the system are the noncomplex import of data in the popular ESRI-Shape-File-Format and the comfortable configuration of the database with the help of the graphical interface pgAdmin III (www.pgadmin.org). To overlay geodata with different reference systems in one map the coordinates have to be converted on the fly. This functionality is offered by the cartographic projections library Proj.4 and supported by the deployed database. The client suite Mapbender serves as graphical user interface of the Web-GIS. It provides customizable desktops (GUIs) for viewing, navigation and querying of OGC compatible services like WMS, WFS and WMC (web map context). In addition, the software contains different components for user management, access protection and catalogue services. Access to the interfaces, their inherent functionalities and services is restricted to registered users. They are created by the administrator and allocated to different user groups. The management of users and user groups, map services and desktops is handled like the data storage itself in the PostgreSQL-/ PostGIS-database. The Open Source system Mapbender is programmed in PHP and JavaScript and can at anytime be adapted to project specific requirements.

3.2 Functionalities of the Web-GIS-application Basic functionalities of the Web-GIS include the pure visualization of the base data in the form of topical map layers concerning land use data, political structures, nature reserves and geographic regions as well as physical geographic parameters like soil, relief and climate of the investigation area. Users can compose their individual maps by switching layers on or off. The WMS-standard allows the implementation of topics, background maps and satellite pictures of remote map servers. Furthermore simple point queries are possible with regard to the attribute data of the geometry data. For better performance, extensive datasets are divided into map sections, which are stored separately in the system. To get a quick overview of the existing data of a specific landscape section, a user friendly search function was implemented. You can zoom into a landscape section by drawing a bounding box over it. At the same time, all corresponding records are listed with their storage place in the file system. In addition, the correspondent link to the meta database is shown. To search the datasets for certain criteria, PHP and SQL based functions were integrated. They are based on the WFS standard and self programmed script adaptations. Consequently the desired objects can be selected by the logic combination of different themes and tables respectively. The selection follows the principle choice of topic (table) => choice of attributes (columns) => choice of criteria (conditions). With this kind of questioning the user needs no knowledge of the internal data structure or of a special retrieval language. He composes his queries with a few clicks on selection lists or drop down menus. The selected criteria are stored in variables of the PHP scripts and inserted into the predefined SQL statements. In doing so, data storage in a PostgreSQL-/ PostGIS- database supports the embedding of spatial functions like position relation or area calculation in the request. The calculated results are marked subsequently in the map. Before the termination of a Web-GIS-session, the current map composition can be saved permanently, including the last map section, the embedded WMS services and their layers, the used coordinate system and further adjustments. After logging in again and loading of the respective session, the working process can be continued at the same point. This is realized by the support of the WMC specification in Mapbender. The services can be generated, stored and reloaded by all client applications with implemented WMC standard. Thus an exchange of WMC documents between the subproject members is ensured and the work can be continued by different users. WMC calls equal XML documents, which contain metadata of the mentioned session settings and resemble workspaces or projects of a desktop GIS.

4 Summary and prospect The interdisciplinary environmental research project SFB 299 requires a flexible and straightforward system of data exchange among the subprojects. From the outset, a system of central data management was established in order to offer a transfer to all of the involved workgroups and encourage them to use the database. The information system is composed in classic client/server-architecture. The website is realized by the framework Typo3. In addition Typo3 offers the project members a number of functions for data and information exchange. These comprise standardised web forms for data input and data retrieval in literature and meta databases. The Open Source approach offers many advantages due to its systems which are largely platformindependent and its freely accessible source code. Open Source programs mean that the system can be programmed so as to modify or add any functions which are lacking, allowing other requirements and functionalities to be easily integrated in the future. The Open Source Web-GIS-component forms a central element of the information system. It contains the UMN MapServer and the client suite Mapbender. This software permits the browser based visualization and analysis of spatial data to all SFB co-workers without the use of a special GIS software and the respective software knowledge. The current feature list contains possibilities for creating and printing of maps of selected regions and topics as well as punctual attribute queries. Furthermore the existing datasets can be searched, which helps to find the required data. In addition, queries can be composed by selection lists; thus objects with special feature combinations can be found and marked. The integration of

WMC standard permits the saving and loading of current Web-GIS-sessions among different clients. In the course of large-scale environmental projects, all scientists should be able to access the data and metadata they need without difficulty, and today's technology makes this possible. The synergetic effects which result from such data transfer more than justify the modest effort and expense involved in creating such a system. The implementation of digitising and a feature editing function, which will allow writing back to the database, is planned in the further development of the Web-GIS-application. In this way features can be added and modified without the use of a desktop GIS. The new features are immediately available to all co-workers of the research project. After project finish selected research results should be presented to public with the Web-GIS-application. For example, interactive maps show different land use options and their ecological and economic impact in an overall map.

5 Literature Altmann, W., Fritz, R, Hinderink, D., 2003. Typo3 Enterprise Content Management. Open Source Press, München. ESRI, 2004. ArcIMS 9 Architecture and Functionality. ESRI White Paper. Kropla,, B., 2005. Beginning MapServer, Open Source GIS Developement. Apress, Berkeley. OGC, 2007. OpenGIS Specifications. Open GIS Consortium, Inc. http://www.opengeospatial.org/standards/ last accessed March 2007