AW: [MAPSERVER-USERS] Hiding overviews

[Eichner, Andreas - SID-NLK]

Ok guys. I examined the situation and came to the conclusion that it is
a bug in MapServer.
In the source of mapserver v5.0.2, file mapwms.c, line 1071:

> msOWSPrintEncodeParam(stdout, "LAYER.NAME", lp->name, OWS_WARN,
>                          "        <Name>%s</Name>\n", NULL);

should really be

> msOWSPrintEncodeMetadata(stdout, &(lp->metadata), "MO", "name",
OWS_NOERR,
>                         "        <Name>%s</Name>\n", NULL);

since the code conflicts with the comment in the code on line 1747 in
the same file which states:
  "Layer Name is optional but title is mandatory."
Which exactly agrees with the specs which states at page 25 of v1.3.0:

"7.2.4.6.2 Title
A <Title> is mandatory for all layers; ..." and

"7.2.4.6.3 Name
If, and only if, a layer has a <Name>, then it is a map layer that can
be requested by using that Name in the LAYERS parameter of a GetMap
request. A Layer that contains a <Name> element is referred to as a
"named layer" in this International Standard. If the layer has a Title
but no Name, then that layer is only a category title for all the layers
nested within. A server that advertises a Layer containing a Name
element shall be able to accept that Name as the value of LAYERS
argument in a GetMap request and return the corresponding map. A client
shall not attempt to request a layer that has a Title but no Name."

IMHO this means you can ommit the <Name> but have to provide the
<Title>. And if the layer has no name it can simply not be requested in
a GetMap-Request. If I change the code like above I have to provide a
"wms_name" in the METADATA part of the MAP file to make the layer
queryable. If I ommit "wms_name" then the layer get's no <Name> and can
therefore not be requested by the client. IMHO it's then up to the
server whether or not to render that layer which is exactly what I want.
For overviews I want multiple layers where only one is active for a
given scale but which one is up to the server. Therefore a client should
not be able to explicitly request one of them. Instead I group those
layers in a named layer by a GROUP clause.

So please check this out. May be we should file a bug report on that.
But I think someone else should confirm this...


Best regards,

Andreas Eichner