[DotNet-OSGeo] some random thoughts

Tue Jun 1 14:14:20 EDT 2010

I would recommend using Mono's IDE monodevelop.com<http://www.monodevelop.com>
This would guarantee that everyone has access to the same IDE.
Plus lately it has made some great progress and has all major features needed for an IDE.

Donny Velazquez | Civil Solutions, a division of ARH | Lead Software Developer
850 S. White Horse Pike, Hammonton, NJ 08037
': 800.924.0482 ext 215| Fax: 609.704.8011
• dvela at arh-us.com
www.civilsolutions.biz<http://www.civilsolutions.biz/>
________________________________
From: dotnet-bounces at lists.osgeo.org [dotnet-bounces at lists.osgeo.org] on behalf of Harold Dunsford [hadunsford at gmail.com]
Sent: Tuesday, June 01, 2010 2:06 PM
To: John Diss
Cc: dotnet at lists.osgeo.org
Subject: Re: [DotNet-OSGeo] some random thoughts

So this is a great conversation thread that you guys are starting.  I have a lot of experience with working more towards the pure windows forms application side of things, and less so as far as setting up web stuff, so we can use ideas about how we need to tweak things for optimal compatibility with as many folks as possible.  I agree with the principals outlined in the previous posts and much of this is simply good coding convention.  I have been using resharper in order to set up some formatting rules, but I suspect that people won't necessarily want to pay for it, so if you know of something else to help with that, I'm interested.  I like trying to set things up so that people can use C# express in order to work with the libraries, however, I am getting reports that people writing plug-ins might not be able to have their plug-in launch an external program for debugging from the express version.  Also, I'm not sure about the implications with trying to use system.Reflection for run-time referencing in other platforms.  Is it ok to use, for instance, a plug-in architecture for referencing OGR/GDAL, or should we be thinking in terms of porting content to C#?

So we currently have source code that is good for accessing shapefile data in C#, but it doesn't offer anything close to what OGR or other vector providers could do.  It also relies heavily on the unmanaged GDAL libraries in order to support various image/raster data formats, via a plug-in architecture.  Unfortunately, according to your comments, it also makes use of DataTables.  (It can either load all the data at once for small dbf files, or can set up a page query to take advantage of the virtual data tables in .Net, but it does not take advantage of the new IQueriable structures or linq)  I like linq, but what I have done with it tends to work extremely well for scenarios where the developer knows the schema ahead of time, and I'm not sure how well it works in situations where you were dealing with the unknown schema.  However, I'm sure there is a way to make all that work, I just haven't done much of it yet, but would not mind tailoring our data access libraries to move more in that direction.

Once Dan sets up an IRC line, I will be happy to get on it.  I'm not a current IRC user, (we used Windows Live Messenger).  However, I have no problem switching over to that.

I'm really looking forward to getting our libraries out there in a way that is more useable and more versatile for everyone.  I also appreciate the time that you guys are putting in in order to take this idea seriously.

Ted Dunsford (Shade1974)

On Tue, Jun 1, 2010 at 10:12 AM, John Diss <john.diss at newgrove.com<mailto:john.diss at newgrove.com>> wrote:
Hi Dan please see comments inline:

Also you may be interested in Mono.Addins and MEF for your plugin architecture consideration.. alternatively spin up new App Domains to host your plugins.

All external apis where possible should be parallelizable. E.g collections should be synchronized.
Cool, but not sure how feasible. Thoughts?

I am thinking along the lines of the new System.Collections.Concurrent namespace. Computers aren’t getting any faster - we need to make sure we can use as many cores as possible to get the speed gains we need.
Parallelization is also very hard to retrofit so if we can get a plan in early we will benefit.

Data access should be async.
Especially for web based data access. Maybe not for file based?

IMO all IO bound access should follow the same pattern : web, db or file. There is no point hitting datasources sequentially when you can do so in parallel.

There should be a caching block developed with multiple backends. Uses ranging from caching data/ partial screen renders, wms/wfs output etc.
Not sure exactly what the implications are... but interesting idea.

Basically have a generic caching block with rules for scavenging and a variable backing store which can be plugged into any part of the processing /rendering pipeline. It could be equally at home as an in-memory cache of features on a layer or as an image cache speeding up identical wms requests. – There is some work on this in the asp.net<http://asp.net> bits of SharpMap2 but it could be made more generic..

Supported frameworks should be considered up front - my personal preference would be to start with a clean slate at .Net 4 or at a minimum 3.5.
We were targeting 3.5 because it would be more likely to be mono compliant... (does MONO really support all of .NET 4 now?)

Miguel certainly seemed to think so in a vid I saw recently.. http://mono-project.com/Compatibility tells a slightly different story - but being an OSS project the documentation is out of date and probably wrong :) I will try and locate the vid.

If we hope to support MONO (which I think we should) we must ensure that any rendering api's have a potential replacement in Mono. Mono is currently compatible with .net 4.
 Any ideas on how much of .NET 4 is implemented in MONO now?

See above – I think they are also working on making the GC better.

Any class expecting to retrieve (vector/attribute) data from a datasource should demand IQueriable<I/TFeature> rather than a FeautureProvider or similar. DataTable / Dataset should be avoided. The query syntax should be either linq against TFeature and/or based on expressions taken from the OSGeo Filter spec.
Not sure I understand... can you explain further?

It was partly a spelling mistake on my part: should have been IQueryable<IFeature> which is basically the underpinning of Linq.
The OsGeo filter spec details a dialect for describing a query which is similar to the System.Expressions namespace used in defining Linq queries. Both would also provide an easy mechanism for serializing/persisting queries.
Datasets and DataTables are very heavy/ verbose and don’t exist on certain platforms. Pretty much all the trends as far as I can see, is to kill them off in favour of domain entities / ORM. DataTables / Datasets are also frowned upon in WCF which is another set of technology that could be very useful in this field. We have an expression model in SharpMap 2 but it is a bit clunky at the moment and disconnected from linq.

Silverlight/Moonlight has massive potential for browser based gis / mapping / processing / grid computing. Supporting it should definitely be planned for but it imposes its own forced async style which may have implications elsewhere. Also win phone 7 will be Silverlight based. Novell have MonoTouch and MonoDroid in progress for IPhone and Android respectively and www.KoushikDutta.com<http://www.KoushikDutta.com>  is working on another free Android/Mono platform.
What are all the implications of supporting Silverlight and Moonlight? Is it possible to have a standard .NET DLL that can be used in a Silverlight application?

The binaries are compatible at .net 4 not so previously afaik. Silverlight is both a super and sub set of  WPF so there are differences. System.Data is one key difference. IMO WPF and Silverlight will merge into one over the next couple of releases.

MS C#/dotspatial group style guidelines should be followed -  everyone’s code should look the same. Perhaps a developer R#/stylecop profile should be created and enforced by a CI server.
Agreed. Is it possible to do this kind of enforcement using Codeplex?

I don’t think codeplex allows this. I have heard good things about Jetbrains’ TeamCity  and lots of people use CruiseControl. BTW jetbrains give away R# licenses.

Source control should be backed with a CI / Test server.
Can this be done on Codeplex?

Not afaik.

Perhaps the logs should be taken and made available somewhere.
Yeah, any ideas on how to do this other than just through the codeplex log browser?

I actually meant the IRC logs.

Documentation should be easy to find and of high quality. Perhaps the group needs a sister website separated from codeplex where it is easier to manage the wiki/ public contribution etc. The codeplex wiki is very limited in this respect.
Yes agreed. This is the number one complaint I believe of any/every open source GIS project that there isn't adequate high quality documentation. We've registered "dotSpatial.org" so maybe that should point to a non-Codeplex server where we can maintain documentation and project description/etc. Then have pointers to the Codeplex site for source code, issues and forums. What do you think of this approach? Would you (John or others) be interested/willing to help decide what would go such a separate site? layout, etc?

I am happy to help out wherever I can..

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