Within SA-ISIS, components of the previously separate initiatives which are now included in the project, and funded by the Innovation Fund, are identified as:

* Agriculture.

* Biodiversity and conservation.

* Coastal and marine.

The aim is to make both spatial and nonspatial data and information on the environment available and accessible to a wide stakeholder group through the connectivity of the Internet. The SA-ISIS Project is a multicollaboration, integrated initiative. The principal investigators include RC-ISCW (Agricultural Research Council - Institute for Soil, Climate and Water); CSIR Environmentek (Water, Environment and Forestry Division) and CSIR icomtek (Information and Communications Technology); and the University of Pretoria, Department of Zoology & Entomology and Centre for Environmental Studies.

Integrated solution

GMS's technological innovation goal for SA-ISIS was to integrate resources from various parties, without having to move all the resources to a central place. This would mean that resources would be available centrally, but with the added advantage that the resource is still residing at the custodian's site. This means that the custodian still has control over his data in terms of availability and maintenance.

One of the main technical challenges was to create a GIS map that is composed from multiple, geographically separated ArcIMS machines. Although this technology is available by using vector streaming, this is not viable over slow Internet connections. GMS could not find technology anywhere in the world that would enable them to serve maps from multiple ArcIMS servers without using vector streaming.

As a result, GMS had to create this new technology themselves. A new HTML viewer was created from scratch. This communicated with a central map server, which was also written by GMS. This map server in turn decided which layers would be rendered by which ArcIMS machines and instructs them to do so. It then retrieves all the separately rendered layers and combines them into one map, which is passed back to the client HTML viewer.

This means that ArcIMS machines sitting at the University of Pretoria, the University of Stellenbosch and in central Pretoria could render the map the client is seeing without him even knowing this. The map server keeps track of the state of the combined map project for each client, including layer visibilities, current extent, etc without having to store state information on the client browser. All this was accomplished without streaming vector data, thus enabling the geographically separated servers to be connected to the central map server with only an Internet-type link and still give reasonable response times.

The involved parties' data is now available from a central server without having to actually reside on the central server. This leaves the custodians of the data free to decide which layers they want to be available for the SA-ISIS portal and also to set up and maintain the layers at their own premises on their own hardware.

GMS

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