is there a way to adjust the transparency of each individual layer?

Question

Problem: In my viewer, the operational map is provided by a service based on a mxd which includes more than 20 layers(in different group). I like to dynamically adjust the transparency of each individual layer by slider.

Thought on this issue: I searched all the posts on the transparency issue in the forum and found that no good methods. Some posts said to load the same service in config.xml several times and each time set some layers visible. While this is not a good idea if have too many layers. I think this problem is resulted from the limitation of Flex API. Only the whole service is a dynamic layer object, while all the layers under the service are not treated as objects though we can get the layers information. Thus many operations based on each individual layer cannot be done if we dont have the object. Whether my understanding is right or not?

Thanks everybody who shares your ideas on this.

Yee

yeeouyang · Answer

Thanks, Robert.

You mean that the problem could be solved in ArcGIS Server 10 REST API? and I still need to load all the layers in the service one by one?

I will look at the new features of ArcGIS Server 10 REST API. 
Yee,

Well you are close but the issue is NOT the Flex API but the REST Endpoint that is used. A map service returns images of the maps extent from the server and is just one image so individual control of sublayers is not possible. Now with ArcGIS Server 10 this is a different ball game with the introduction of feature layers or feature services that are individual layer/sublayer control, but you are still in the situation where you would have to load all 20 of your layers individually and loose your groupings.

RobertScheitlin__GISP · Answer

Yee,

Well you are close but the issue is NOT the Flex API but the REST Endpoint that is used. A map service returns images of the maps extent from the server and is just one image so individual control of sublayers is not possible. Now with ArcGIS Server 10 this is a different ball game with the introduction of feature layers or feature services that are individual layer/sublayer control, but you are still in the situation where you would have to load all 20 of your layers individually and loose your groupings.