GeoWebCache 1.1.0 (finally) released

[Arne Kepp]

This release was originally planned for the end of February, and it is
therefore with great relief that I can announce 1.1.0

The artifacts have been uploaded to SourceForge, it may take another
hour or so until they are available for download. The following is a
copy of http://geowebcache.org/trac/wiki/Version1.1.0 , it may be more
readable on the web.

Outline:
  1. Major new features, details below:
    a. JDBC based storage of meta information, a solid investment in
GWC's future
    b. Modifiable parameters
    c. Basic WFS caching
    d. Automatic configuration merging
  2. Errata
  3. XML documentation
  4. Roadmap / Menu
  5. Upcoming license change
  6. GeoServer update
  7. Bugs?

1) Major new features
The major new feature in GWC 1.1.0 is the introduction of a very fast H2
database to store meta information. It is mainly an investment into
GWC's future, except for modifiable parameters the 1.1.0 release makes
very little use of the new backend. It will however be key for
collecting statistics, perform automatic pruning of tiles that are
rarely used and to efficiently find them without scanning millions of
filenames.

1.b Modifiable parameters
Normally a tile cache will only use the layer name and the bounding box
to determine what tile to return to the client, all other parameters are
typically ignored. GeoWebCache took this one step further by allowing a
separate set of tiles for each SRS. Modifiable parameters allow you to
specify a set of parameters and allowed values, each combination will
result in a separate, new set of tiles.

Sample definition of modifiable parameters, this is the last item in a
wmsLayer element:
  <regexParameterFilter>
    <key>STYLES</key>
    <defaultValue></defaultValue>
    <regex>^(|polygon|population)$</regex>
  </regexParameterFilter>

<key> is the query string key,  ?request=getmap&STYLES=....
<defaultValue> this is the default value GWC will send to the backend,
if the request from the user does not provide one.
<regex> the regular expression for the string between the "=" and the
"&" delimiting the next parameter. Leave this blank if you want to
accept anything.

Note that the example above overlaps with the wmsStyles configuration
directive. Be sure to remove the wmsStyles element if you want the user
to be able to modify it.

There is also a separate filter for floating point values, see the
default geowebcache.xml for details. It is also relatively easy to make
new filters.

1.c Basic WFS caching
GeoWebCache 1.1.0 supports very basic WFS caching. The results from
queries are stored to disk, there are currently no functions for
inspecting them or programmatically removing them. The algorithm relies
on computed hashes and does not check for uniqueness, so there is a
minute chance for collisions. The motivation for this development was
the SHP-ZIP (zipped shapefile) outputformat in GeoServer. These files
can be huge and tremendously expensive to compute. This WFS service is,
in its current state, not intended to be used for more complicated cases.

To use it:
You can edit the "gwcServiceWFS" bean in geowebcache-servlet.xml. It
allows you to specify the URL to a WFS backend, as well as a regular
expression filter for queries that you want to support. The WFS service
is then mirrored at http://localhost:8080/geowebcache/service/wfs


1.d Automatic configuration merging
geowebcache-servlet.xml is now setup so that it first reads
getcapabilities, if you use this feature, then geowebcache.xml. If the
same layer name is encountered in both configurations, attempts are made
to merge the two configurations. When this happens a statement is
written to the log.

This allows you to specify additional SRSs, or modifiable parameters,
for layers that already exist.

2) Errata:
Known issues in this release
  a. Tiles generated by 1.0.x will be ignored/overwritten. Please get in
touch if this is a major problem, we may be able to make conversion utility.
  b. There is currently no code for truncating the cache. Stop the
servlet and delete it manually.
  c. Hashes are used to generate the paths for the blobs. These are
currently not checked for uniqueness.
  d. H2 does not completely let go of all open files when the servlet is
stopped and undeployed. You may have to wait a few seconds and delete
them manually.
  e. The seeder does not support modifiable parameters. The default is
always used.

I hope to start working on 1.1.1 straight away, to fix b, c, d. Possibly
e as well.

3)  XML documentation

I have documented geoewebcache.xsd fairly well,  though I am not
entirely pleased with the way the documentation compiler renders the
comments. Nonetheless, it is available here:

http://geowebcache.org/schema/docs/1.1.0/

The XSD file itsels is available here:
http://geowebcache.org/schema/1.1.0/geowebcache.xsd , it may be just as
easy to read that, if your XML tool does not support the annotations.


4) Roadmap / Menu
I, and many of you, have lots of ideas for improving GeoWebCache.
Unfortunately, it does not look like there will be a lot of dedicated
time to work on GWC moving forward. After 1.1.0 I will probably focus on
improving WFS-T integration in GeoServer 2.0.

I have therefore started collecting fleshed-out ideas on the
[wiki:roadmap roadmap page]. Please get in touch if you are an OpenGeo
EE customer interested in any of these features, or can provide funding
through other means. Most of these things are based on ideas coming from
you or external sources, feel free to suggest more, preferably through
the mailinglist so that we can discuss them first.

5) License change
GeoWebCache was intended as a library for GeoServer, and consequently
released under the terms of the LGPL. However, it quickly evolved into a
freestanding application. For this reason, OpenGeo (and me, personally)
find the GPL more appropriate for this project. I have over the past two
months contacted contributors to get their opinion, no objections were
voiced. 1.1.1 will therefore be released under GPLv2, with the intention
of moving to GPLv3. I have carefully reviewed all code on trunk and I am
satisfied that The Open Planning Project, the non-profit organization
behind OpenGeo, holds all copyrights.

If you are building closed products off GWC then please get in touch, we
may be able to offer a dual-license. If this were to happen then any
resulting funds would be channeled directly back into GeoWebCache and
GeoServer.

6) GeoServer update
I will most likely distribute updated JARs after the developer meeting
on Tuesday.

7) Bugs?
If you find any bugs, please take a moment to report them through Trac
at http://geowebcache.org

-Arne

--
Arne Kepp
OpenGeo - http://opengeo.org
Expert service straight from the developers


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[DavidRobison]

Does GoeWebCache support tiling for EPSG:3338 NAD83 / Alaska Albers?
Thanks, David

--

David R Robison
Open Roads Consulting, Inc.
103 Watson Road, Chesapeake, VA 23320
phone: [phone]
e-mail: drrobison@...
web: http://openroadsconsulting.com
blog: http://therobe.blogspot.com
book: http://www.xulonpress.com/book_detail.php?id=2579


 



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[Arne Kepp]

GWC is agnostic to EPSG codes, but you have to configure it manually.

-Arne


David R Robison wrote:
> Does GoeWebCache support tiling for EPSG:3338 NAD83 / Alaska Albers?
> Thanks, David
>
>  


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OpenSolaris 2009.06 is a cutting edge operating system for enterprises
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Go to: http://p.sf.net/sfu/opensolaris-get
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