[mapserver-users] fast cgi MapServer (version 6.0.3) vs cgi with awms getmap request

thomas bonfort thomas.bonfort at gmail.com
Fri Nov 9 00:38:39 PST 2012


On Fri, Nov 9, 2012 at 9:16 AM, Eichner, Andreas - SID-NLKM <
Andreas.Eichner at sid.sachsen.de> wrote:

> >> Once the request is done the the connection
> >> will be closed.
> > I thought that setting allows to open the db connection only
> > once , keep it open until all layers data are read and will
> > prevent closing and opening connections in between layers ?
>
> That's right. You can query more than one layer per GetMap request and
> MapServer will open the database connection only once for all layers
> involved. But once the request is done AFAIK the database connection
> will be closed.
>
In CGI mode, a single connection will be reused across all layers of the
request.
In FastCGI mode, a connection will be kept open during the lifecycle of the
fastcgi process, i.e. the connection will not be closed at the end of a
request.


> > I searched the list and the MapServer doc about the Apache ? Module
> > mod_mapserver, however I could not find almost any reference
> > to it other than it is on the wish list for v 6.2 ? Does it already
> > exist in MapServer 6.0.3
>
> The module is only available in the 6-2 branch and should be build when
> supplying the --with-apache-module switch and configuration should be a
> snippet in the apache config:
>
>   <Location "/wms" >
>     Mapfile /path/to/wms.map
>   </Location>
>
> But I'm sure it's not well tested and only supports WxS services. You
> might ask Thomas Bonfort in what stage it is. Even if it's currently
> not suitable for productive use you might give it a try and provide some
> feedback. If it can solve your performance issues it might get more
> attention by the developers.
>
It's there in 6.2 but we will not be advertising it as being ready for
production. In practice the same mapfile is reused across requests, which
makes for very good performance but has the following implications:
- WFS requests with FILTERs set should not be used, as the
FILTERITEM/FILTER will continue to be applied to the subsequent requests,
even if FILTER was not supplied on the subsequent requests.
- CGI substitutions and mapfile url overrides should not be used, as they
would also be applied to subsequent requests
- WMS SLD requests should not be used, for the same reason.

Basically, the only safe usages are capabilities and plain GetMap or
mode=map requests. Overcoming the previous limitations isn't planned for,
so would need to be funded. It should be noted that these limitations would
also apply to a homemade mapscript script that reuses a mapObj for multiple
requests.

regards,
thomas

>
>
> HTH
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