Map image layers

[mshanaghan]

What is the purpose of having map image layers in addition to hosted feature layers on the portal?

In what situations are map image layers more effective than hosted feature layers?

Thank you.

[NicolasGIS · Accepted solution]

To me, the main limitation of hosted feature layers are symbology and labels.

You can’t have hatch or symbologies like arrows on lines to represent slopes and other complex symbology. In the same way, the labelling engine is not as powerful as what can be done server side and result many times in overlapped labels.

For all those reasons, I can’t manage our GIS solely with hosted feature layers. 

Maps SDK 4.X solved the issue of renderering many features at the same time which could also have been one reason to choose Map image Layer over feature layer for some dataset.

There must be others but that the main ones on top of my head.

[TanuHoque · Accepted solution]

Thanks @NicolasGIS.

I'd like to add a few points and add some references to our docs for more info.

1. different types of data source - raster, TIN etc.
2. often folks have datasets across multiple databases (e.g. polygon feature class representing parcels in a geodatabase, but ownership information are stored in a separate database), and they want to join (or create relationship) them and serve them out as a map service
3. dynamic aggregation
4. by reference - since map service gets (most often) published by reference, as you update your data from any esri products (ArcGIS pro, arcmap etc.) or 3rd party app, they will be reflected on your app. No reason to do any additional steps to sync.
5. performance - since the service lives closer to the dataset, it often performs better to draw them on the server side as there is no need to send data across the wire to get drawn on the client app.
6. security - some cases authors don't want their end users to have full access to geometries or attributes. Since everything draws on the server, an author can configure a map service such a way that end users won't have access to download all data.

Ref:

• https://enterprise.arcgis.com/en/server/latest/publish-services/windows/what-is-a-map-service.htm
• https://enterprise.arcgis.com/en/server/latest/publish-services/windows/common-reasons-for-using-map...
• https://enterprise.arcgis.com/en/server/latest/publish-services/windows/supported-functionality-in-m... 

 hope this helps

[mshanaghan]

Thank you both. This is very helpful.

[TanuHoque · Accepted solution]

oh one other thing - there are cases when you want to add a layer as a feature layer in a web map for client side drawing and interactivity. You can still do that by using the url of a layer inside a map service. for example:

• https://sampleserver6.arcgisonline.com/arcgis/rest/services/SampleWorldCities/MapServer --> it gets added as a map image layer
• https://sampleserver6.arcgisonline.com/arcgis/rest/services/SampleWorldCities/MapServer/0 --> gets added as a feature layer

[TanuHoque]

Thanks @AlizaNaz for providing additional info.

Just a quick clarification -- Map image layer (aka map service) doesn't necessarily mean 'cached/tiled map service'.

There are two types of map services:

1. Dynamic map service (that is the default one)
   • as the name says, data don't get cached; it always gives you back the latest data
2. Cached/Tile map service