Cached vs. Dynamic map service

Because a map service responds to visualization requests with an image of the features, it needs to generate that image server-side. A dynamic map service draws this image every time it receives a request. A cached map service, on the other hand, means that every image is generated and then saved ahead of time. Requests on a cached map service receive this saved image.

Draw time differences

Drawing the image takes time, so a dynamic map service will be slower than a cached map service to respond to requests. But creating the cached map service in the first place is generally much slower, because every image in the cache needs to be created up front.

Data update differences

Because a cached map service sends a saved image for every request, it may not reflect the most recent data. The cache would need to be recreated for the image to update. Dynamic map services, however, will always show the most recent edits to the data. For that reason, cached map services are typically best if the data are rarely updated, while dynamic map services are typically best for data that are frequently updated.

Questions

1. If you have a map service of parcels that are updated quarterly and is used as a basemap by many different users, should that service be cached?
2. If you have a feature service that is edited annually, should that service be cached?

Summary

	Cached Map Service	Dynamic Map Service
Geometry drawn	On cache creation	On every request
Service creation	Slower	Faster
Service response time	Faster	Slower
Reflects most recent edits	❌	✔️
Best for data that	Rarely change	Often change