I have a requirement to generate map images with polygons symbolized on data from an external source. The source is a REST API. The REST API is fairly elaborate and changing it is not desired.
I'd like to make a SOI which when requests are made against the MapServer will query the external API, get some more data, mash it together with the geodatabase data, then return the image. The image needs to be symbolized based on values from the external API.
Does this sound reasonable through a SOI? I've seen an example which adds new fields from an external database which looks close to what I want to do. https://youtu.be/gYmFarHEMgw?t=2639 In order to follow this example, but also symbolize, would I need to symbolize on an existing field in ArcMap and change the values of the field used for symbology with the SOI rather than add a new field?
Do I need to use an SOE instead of SOI if I'm interested in adding parameters to the request? As in I want to get the image, but with parameter A make call A to the API turning all the polygons red, with parameter B call B and turn all the polygons blue.
Some other options have been considered and rejected. Pulling the data from a feature service and the REST API and combining the data client side is not desired.