M.S. (Informatics and Architecture),
Rensselaer Polytechnic Institute,
Residence: 151, Apartment # 1,
Troy, New York-12180
Abel and Rusdi
Rapid growth of the World Wide Web has proven its worth as medium of information transmission. With both audio and visual data dissemination capabilities, it has been accepted as an effective communication tool. Development of spatial information technologies over the past few decades (primarily the development of Geographic Information Systems (GIS) and raster image processing and modeling tools) have made the handling and manipulation of spatial data relatively simple.
Until the recent past, much of GIS data was manipulated and used predominantly by select few who had access to GIS data and were trained in handling spatial databases. With the increasing use of GIS technology in various fields and with the growing importance of information distribution, the World Wide Web provides an ideal medium to make these previously advanced GIS tools accessible to a wider audience. The development of HTML and associated client-server technologies has enabled the growth in information access and distribution.
The ‘Albany information warehouse’ acts as a platform for information exchange at city level as well as at community level by the members of that community or users hunting for information. By information, we specifically mean information that has spatial context to it. Geographic Information systems are the technology that is used to manipulate, store, retrieve and access spatial data. GIS stores data of objects in geographic locations and related descriptions of it in layers.
This project is structured with focus on the information exchange between cross platforms and cross applications, namely the GIS and the hypermedia. Remote clients use the web technology to get their queries across to the remote server, which has GIS application residing as tool to extract information from the spatial database and throwing the results on to the client. Started as a purely experimental project, based on technological limitations of the various components of the entire communication process, the project has been knit together using non-conventional data exchange methods and applications. The elegantly minimalized user interface (the webpage) is aimed at organizing information to the users in a comprehensible manner. This has been done keeping in mind the broad range of users (from different age groups, backgrounds, socio-economic backgrounds, etc.) that the site would cater to. Accommodating commercial, infrastructural and housing information, the most common use of this platform would be to aid users who are new to Albany, as well as the residents of Albany community in their search for information required in daily life.
Back end technology:
The Common gateway interface is comprised of a visually elegant interface layout using HTML. The information is stacked in sections for structuring purposes. When the user at the client end posts a query on the front end, the request invokes the associated dynamic link library (DLL) files, which communicate with the web server and parse the query into components. As in dynamic content approach, this DLL helps trigger the correct VB application to make a connection to the MapInfo Server. The Visual Basic files have a sequence of related commands in a GIS compatible format for the final data extraction and delivery.
The spatial database has data, which is geocoded to each location on the base map. For this project the GIS software package used was MapInfo. Integrating MapInfo to the commands sent out by the VB executables was done by using MapBasic (MapInfo’s programming language). The embedded MapBasic commands use dynamic data exchange (DDE) method to exchange data from the Visual Basic codes to MapInfo. MapBasic instructs MapInfo to perform required tasks in order to generate query results and save the final results as image maps (JPGS). Once the image is generated it is placed in a directory where the web pages can access it.
Thus to sum it up, the parameters passed over by the client to the DLL was passed on to the Visual Basic code, which had MapBasic code embedded in it. This Map Basic set of commands further instructed the GIS application MapInfo, using dynamic data exchange method, to exchange data and perform the queries and finally save the query results as JPEG maps. The graphical layout of this experimental technology setup is given below.
The action plan for the research was follows:
- Collection of the housing, land-use, topographical, commercial and available infrastructural data of Albany. Collection methods included collection from local governmental agencies. Some of the data was mocked up for unavailable data and thus this project should be considered as purely experimental.
- Creation of relevant database and normalization of data to avoid noise or misleading results.
- Conversion of data in GIS application importable data format and the creation of the spatial database.
- Researching a method of communicating with an application not designed for web use (MapInfo). In our case, Microsoft’s DDE was chosen.
- Researching and devising a method of engaging the queries from remote client (thorough the World Wide Web) to trigger off GIS application and perform the required queries and finally transfer results back to the client from the server.
- Interfacing the GIS application with the webpage to allow query from client to be implemented by the GIS application on the remote server.
- Display of the queried results in a simple and easy-to-understand webpage. Special emphasis has to be laid to the wide range of users that this web resource is expected to cater.