Dear Gerben,
The <LayerLimit> tag is set by default in ncWMS and THREDDS-WMS Capabilities
documents to 1. Have you found a server that doesn’t contain this tag?
Note that not all WMS clients respect this tag, so you sometimes get this error
even if the server is set up correctly. Also, I think this tag appeared in WMS
1.3.0, so if your client is “speaking” WMS 1.1.1 then you might see the error.
Hope this helps,
Jon
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 25 Jun 2014 13:00:23 +0000
> From: Gerben de Boer <Gerben.deBoer@xxxxxxxxxxx>
> To: "thredds@xxxxxxxxxxxxxxxx" <thredds@xxxxxxxxxxxxxxxx>
> Subject: [thredds] LayerLimit
> Message-ID:
> <A7673B992F62684F8D30874621A2599F452C3420@V-EXC-C01.DIRECTORY.INTRA>
> Content-Type: text/plain; charset="us-ascii"
>
> A TDS WMS GetMap request returns at most 1 WMS layer per request. If one
> requests more, by specifying a comma-separate list form layers= and styles=,
> TDS returns an error message
>
> <ServiceExceptionReport xmlns="http://www.opengis.net/ogc";
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; version="1.3.0"
> xsi:schemaLocation="http://www.opengis.net/ogc
> http://schemas.opengis.net/wms/1.3.0/exceptions_1_3_0.xsd";>
> <ServiceException>
> You may only create a map from 1 layer(s) at a time
> </ServiceException>
> </ServiceExceptionReport>
>
> However, the WMS 1.3.0 standard prescribes that in this case TDS should
> explicitly mention a <LayerLimit> element in the GetCapabilities:
>
> "The optional <LayerLimit> element in the service metadata is a positive
> integer indicating the maximum number of layers a client is permitted to
> include in a single GetMap request. If this element is absent, the server
> imposes no limit." (page 23, OpenGIS(r) Web Map Server Implementation
> Specification)
>
> This means that THREDDS should add this element to the GetCapabilities
> (LayerLimit=1) (or return more maps to be OGC compliant).
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> End of thredds Digest, Vol 65, Issue 15
> ***************************************
