Which challenge is commonly associated with designing GIS web services?

The challenge commonly associated with designing GIS web services is that Geographic Information Systems (GIS) require heavy CPU usage. This is primarily due to the demanding computational tasks that GIS applications typically perform, such as complex spatial analysis, rendering large datasets, and processing high-resolution imagery.

These CPU-intensive operations can strain system resources, particularly when multiple users are accessing the service simultaneously. This strain can lead to performance bottlenecks, increased latency, and a subpar user experience if the system is not adequately designed or scaled to handle such computational loads.

On the other hand, lightweight clients of GIS services are designed to manage the interaction without requiring extensive computational resources, and the fact that GIS sometimes transmits small images does not inherently represent a design challenge for web services. Additionally, while GIS can be made scalable, doing so effectively requires careful planning and architecture, which indicates that scalability is not an inherent ease in design, but rather a goal that can be sought. Thus, the heavy CPU usage stands out as a notable challenge in the design of GIS web services.