Thank Jukka
This helps a lot. I agree that if there are restrictions, this should be
included in the documentation.
Dominique Bessette
From: Rahkonen Jukka (Tike) [mailto:jukka.rahko...@mmmtike.fi]
Sent: Thursday, September 04, 2014 6:17 AM
To: 'Jody Garnett'; Bessette-Halsema, Dominique E
Cc: 'geoserver-users'
Subject: Re: [Geoserver-users] [Geoserver-devel] wms getCapabilities special
characters
Hi,
This may be TL;DR. However, names with special characters are an eternal
battle. If someone verifies that what I write makes sense it might be good to
include it in some place in Geoserver documentation.
Short version: WMS standard allows anything in layer names but WFS standard
puts strict rules for feature type names. By default Geoserver is using same
names in both WMS and WFS services which means sooner or later troubles if the
more strict rules are not followed. Wise people follow the rule: Name must
start with either a letter or underscore (_) and may contain only letters,
digits, underscores (_), hyphens (-), and periods (.).
Long story: I have been fighting with peculiar WMS layer names and WFS feature
type names sometimes and my current interpretation of what is valid and what is
not is as follows.
In WMS almost anything is allowed in layer names. I base this on WMS 1.3.0
schema http://schemas.opengis.net/wms/1.3.0/capabilities_1_3_0.xsd
It says:
<!-- ** Elements Used In Multiple Places. ** -->
<element name="Name" type="string">
<annotation>
<documentation>
The Name is typically for machine-to-machine communication.
</documentation>
</annotation>
</element>
AND:
<element name="Layer">
<annotation>
<documentation>
Nested list of zero or more map Layers offered by this server.
</documentation>
</annotation>
<complexType>
<sequence>
<element ref="wms:Name" minOccurs="0"/>
So a layer name in WMS is defined to be just a string. Thanks to Andreas
Eichner
http://osgeo-org.1560.x6.nabble.com/cascading-wms-and-layer-names-encoding-td5058504.html
I have learned that xs:string is a
"... finite-length sequence of characters that match the Char production
from [XML 1.0 (Second Edition)]" whereby Char is defined as:
Char ::= #x9 | #xA | #xD | [#x20-#xD7FF] |
[#xE000-#xFFFD] | [#x10000-#x10FFFF] /* any Unicode character,
excluding the surrogate blocks, FFFE, and FFFF. */
or in other words: almost every character.”
However, in WFS situation is different. WFS 1.1.0 schema
http://schemas.opengis.net/wfs/1.1.0/wfs.xsd specifies that feature type has a
name that is of type QName
<xsd:complexType name="FeatureTypeType">
<xsd:annotation>
<xsd:documentation>
An element of this type that describes a feature in an application
namespace shall have an xml xmlns specifier, e.g.
xmlns:bo="http://www.BlueOx.org/BlueOx";
</xsd:documentation>
</xsd:annotation>
<xsd:sequence>
<xsd:element name="Name" type="xsd:QName">
QName stands for qualified name
http://books.xmlschemata.org/relaxng/ch19-77287.html and it is xsd:NCName with
an optional prexif. Finally we get into NCName which has quite a many
restrictions http://www.datypic.com/sc/xsd/t-xsd_NCName.html
Therefore a WFS typeName must start with either a letter or underscore (_) and
may contain only letters, digits, underscores (_), hyphens (-), and periods
(.). WFS typeName which begins with a number is invalid, as well as names with
colons in any place in the body of the name because colon is reserved for the
namespace in the xsd:QName.
-Jukka Rahkonen-
Lähettäjä: Jody Garnett [mailto:jody.garn...@gmail.com]
Lähetetty: 3. syyskuuta 2014 23:19
Vastaanottaja: Bessette-Halsema, Dominique E
Kopio: geoserver-users
Aihe: Re: [Geoserver-users] [Geoserver-devel] wms getCapabilities special
characters
You should ask on the user list :) The devel-list is for those working on the
GeoServer application.
The WMS and WFS specifications dictate what is allowed as a layer name - in
particular the WFS specification should have some limitations based on the
structure of XML documents (which uses the format "prefix:identifier" - where
prefix is mapped to an XML schema namespace).
Check the specifications and let us know what you find? I expect in this case
that even if GeoServer lets you add additional characters XML parsers and WFS
clients will not be able to handle the situation.
(Note the GeoServer web application and REST API will often allow you to
configure setting that do not work, when you spot an example please report the
issue).
--
Jody
Jody Garnett
On Wed, Sep 3, 2014 at 10:28 AM, Bessette-Halsema, Dominique E
<dominique.besse...@gdit.com<mailto:dominique.besse...@gdit.com>> wrote:
I added a colon ‘:’ character to a grid name. Is this allowed in the WMS
getCapabilities? Or is this a special character? I know this isn’t the
recommended naming convention but it is required and I need to go back and
accurately explain why it may or may not work.
Where in the geoserver code is the WMS getCapabilities name set?
For example: imagery:goes_13.infrared.1km
In the WCS getCapabilities the identifier has the correct name
<wcs:CoverageSummary>
<ows:Title>infrared-goes_13 1km</ows:Title>
<ows:Metadata metadataType="other" xlink:type="simple"
xlink:href="/rest/metadata?request=getMetadata&layer=imagery:goes_13.infrared.1km"/>
<ows:WGS84BoundingBox>
<ows:LowerCorner>-120.0038771 -65.0093883</ows:LowerCorner>
<ows:UpperCorner>-44.9961229 65.0093883</ows:UpperCorner>
</ows:WGS84BoundingBox>
<wcs:Identifier>imagery:goes_13.infrared.1km</wcs:Identifier>
</wcs:CoverageSummary>
In the WMS getCapabilities the Name is not correct it cuts off after the colon
-<Layer opaque="0" queryable="1">
<Name>imagery</Name>
<Title>infrared-goes_13 1km</Title>
…..
</Layer>
The WCS describecoverage looks correct, just odd because of the naming
convention.
wcs:CoverageDescription>
<ows:Title>infrared-goes_13 1km</ows:Title>
<ows:Abstract/>
<ows:Keywords/>
<wcs:Identifier>imagery:imagery:goes_13.infrared.1km</wcs:Identifier>
………….
Dominique Bessette
Engineer, Software
General Dynamics Information Technology
Supporting Fleet Numerical Meteorology and Oceanography Center (FNMOC)
Office: 619-881-2748<tel:619-881-2748>
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