[Geotools-devel] gpx design questions

[Jody G. <jga...@re...>]

Thanks for bringing this to our attentions, I echo Adrian's words - 
great work and welcome!

Here is the list...
>
>     * The parser uses XppReader, which is part of the XStream^
>       <http://xstream.codehaus.org/>project, and which in turn uses
>       XPP^ <http://www.extreme.indiana.edu/xgws/xsoap/xpp/>, a pull
>       parser. [/pro: have experience in it, con: external dependency/]
>
Justin is very interested in the pull parser idea; you may also be 
interested in his binding framework thing - it streams data (so you are 
not limited by size). He has considered switching from SAX to a pull 
parser in the past. If you are familiar with XppReader you guys should 
probably grab an IRC session and talk shop. The best I can do is point 
you towards these docs 
(http://docs.codehaus.org/display/GEOTDOC/XML+Developers+Guide).
>
>     * The data container bean currently stores the geometry, name,
>       description, comment and date values from the file. [/these were
>       just enough for the other project, and as I saw, thees would
>       almost always be enough/]
>
If it is what you got then it is fine. You may want to consider a 
"bounds" for the entire file ... if the information is in a header?
>
>     * The DataStore when created, creates two FeatureClasses, which
>       describe the same features every time: a point class, and a
>       track class.
>
Okay.
>
>     * The DataStore parses the GPX file in the constructor, so if a
>       parser error occurs, the creation of the DataStore itself fails.
>       [/pro: prevents deferred errors/]
>
Sounds fine; sometimes we just parse the header in the constructor - and 
put off parsing the rest until the user actually calls the iterator for 
the first time.
>
>     * The FeatureReader implementations convert the data beans to
>       Feature instances. A waypoint's geometry becomes a Point with
>       lat/lon/elevation, and a track's becomes a MultiLineString with
>       lat/lon/elevation coordinates.
>
Good.
>
>     * The structure of the module is minimalistic in the sense that it
>       depends highly on the default implementations of the interfaces.
>       [/for the sake of fast development, and that is what default
>       implementations is there for. As this module assumes to work
>       with small data, this should cause no performance issues./]
>
Great.

All the best,
Jody

Adrian Custer wrote:
> Hey Peter,
>
> It looks good.
>
> Justin, Jody, anyone else,
>
> The bottom of the page has some design considerations. Perhaps you could
> take 10 minutes to add some comments and pointers. It seems like Peter
> has gotten amazingly far in getting things hooked up and now he could
> use your help.
>
> --adrian
>
> On Fri, 2007-07-20 at 23:43 -0500, Bolla Péter wrote:
>   
>> Hello,
>>
>> Thank you, for the cleanup, it certainly looks better. :)
>>
>> Also I reviewed it again, and separated the current state of the module 
>> and the planned developments, and wrote some words on design considerations.
>>
>> Comments and ideas still welcome!
>>
>> Best,
>> Peter
>>
>>
>> Adrian Custer wrote:
>>     
>>> Hello,
>>>
>>> Glad to see you are getting started. I will be cool to have your module
>>> working in Geotools.
>>>
>>> I made some edits to the layout to make the page, I hope, a bit clearer.
>>>
>>> I would encourage you to re-visit the last part where you discuss the
>>> design decisions you are considering. Specifically, perhaps you can talk
>>> about the tradeoffs or lack of knowledge that led to your decisions.
>>> Also drop the "I was thinking" kind of language in favour of what you
>>> were thinking about.
>>>
>>> cheers and, if I haven't said so before, welcome to the project,
>>>
>>> --adrian
>>>
>>>
>>> On Thu, 2007-07-19 at 20:05 -0500, Bolla Péter wrote:
>>>       
>>>> Hi,
>>>>
>>>> I've created the RnD page on my GPX module. You can read it here:
>>>> http://docs.codehaus.org/display/GEOTOOLS/GPX+module
>>>>
>>>> Any comments and ideas are welcome!
>>>>
>>>> Best,
>>>> Peter
>>>>
>>>>
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>
>