[postgis] Re: PostGIS and ESRI

Paul Ramsey pramsey at refractions.net
Mon Sep 24 15:17:18 PDT 2001

"Matt.Wilkie" wrote:
> > also GeoMedia and MapInfo and AutoCAD) will eventually be able to work
> > with PostGIS as a spatial backend. And in the short term the answer is
> > "no", because ESRI holds an effective desktop monopoly on GIS
> > viewers/editors which they are using to push their own client/server
> > protocol: the protocol used by ArcSDE.
> Does this mean it would be too difficult (not worth the effort) to
> reverse engineer the protocol (a la SAMBA)? 

For the GIS community in general, it is entirely worth the effort to
break the ESRI client/server protocol lock. But for us in particular, it
is not: it would be a very expensive undertaking, far more that we can
support as a small company.

> Or that there is no point
> to developing an open source SDE-compatible server when there are
> no open source clients to speak of? 

I think there is definately a point, for the very reasons you point out
in your own workplace: there is a huge overburden of ESRI software on
the desktop, and the only client/server protocol that software speaks is
SDE. If non-ESRI servers are to make inroads, they realistically need to
speak the SDE protocol.

> (except that Mapserver can access
> SDE directly, yes?)

Yes, Mapserver can access SDE directly. Stephen Lime added that
functionality so that Mapserver could be used by the Minnesota DNR,
which is also heavily invested in ESRI. An SDE developers kit is
available which allows you to program your own SDE client. An SDE server
is another kettle of fish. :)

I have thought about trying to reverse the wire protocol ala Samba, and
it is very tempting. If we had no financial requirements it would be
cool to do "just because". My understanding of the Samba history is that
the original versions were done while the authors were either grad
students or university employees: ie, essentially subsidized by another
big organziation (which may not have really known what their dollars
were paying for). Once the original versions "proved the concept", UNIX
vendors hired some of the Samba team and made contributions. Basically,
there are a few large commercial organizations (Oracle? Intergraph?) for
whom such a piece of work would be desirable and worth paying the couple
hundred thousand dollars of seed money to get started. But for the rest
of us, the cost of reverse-engineering the protocol dwarfs the cost of
an SDE licence.

     | Paul Ramsey
     | Refractions Research
     | Email: pramsey at refractions.net
     | Phone: (250) 885-0632

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