[mapguide-internals] MapGuide Comments

Haris Kurtagic haris at sl-king.com
Tue Sep 11 19:07:59 EDT 2007

Yes, I was also thinking about returning all images at once, I read
about this Image strips (not familiar with those) but sounds like way to

Buffers, I forgot about those.

Thank you,

-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Robert
Sent: Wednesday, September 12, 2007 12:53 AM
To: MapGuide Internals Mail List
Subject: Re: [mapguide-internals] MapGuide Comments


I could not agree more on your first point. In fact I would love to 
optimize that to send some kind of legend image strip in one operation 
to avoid all the round-trips.

As for this comment:

 >>I am setting Map view parameters and request for image in one
 >>good or bad ?

I think your approach is good. In fact that is the way the DWF Viewer 
works as a client.

Sessions are necessary for other stuff, like temporary layers, data, 
etc. A buffer for example creates a temporary SDF and layer. You can 
then use that SDF for further geo-processing, etc.


Haris Kurtagic wrote:
> I am working on MapGuide RESTful service and digging deep into
> I have a lot of good words on what Autodesk guys did, good job.
> I would like to comment on things that I don't like or understand and
> hopefully to hear other opinions.
> 1.       Legend Image Icon creation is very paintfull and error prone.
> To request for Icon you need to send few parameters scale, theme rule
> index, geometry type,...
> What is happing is that viewer's are deciding on geometry type not on
> feature source geometry type but reading from XML ( PointStyle,
> LineStyle, Polygon, Combo ) by string tag.
> Then they will convert it into geometry type (and wrongly for
> - will go to Multi Point). Server rendering is expecting real geometry
> type to find appropriate feature style (getting feature source and
> correct geometry type would be even more overhead).
> I see several problems: here viewers have hard-coded schema elements,
> not correctly setting required geometry type, exception's on wrong
> scale, exception if data on server is changed.
> One of problems is if server can't figure out rule for example setting
> incorrect scale will crash web-tier badly ( null-pointer access).
> This can be repeated with Sheboygan example and if you send request
> District legend icon with scale=0, it will not find it and will return
> null image and agent crashes ( HttpGetLegendImage needs if in 134 line
> or throw exception in server).
> What I think would be right is to have Id for rule so you would simple
> request for image by id instead of ( scale, geometry type, rule index
> I wrote a lot about not so "important" thing but it took us a lot of
> time :)
> 2. Session - what are reasons for having session's ?
> To store Map runtime parameters ( center, scale layers show/hide,
> selection). Viewers are keeping this parameters of map and basically
> doing two requests one to set these properties to runtime map and
> another one to request image.
> To store user credentials - session as token, that I think is  OK.
> I am setting Map view parameters and request for image in one request,
> good or bad ?
> Thanks ,
> Haris
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