[Zope-dev] questions about writing a DA

[Paul Everitt]

I just took a look at ODBC Socket Server, which I had never seen before. 
  Pretty interesting!  Here's some comments.

1) It looks like socket server opens a new socket for processing every 
request.  In this respect, it goes against one of the benefits of 
database adapters, which keep a persistent connection.

2) Architecturally, socket server is very similar to web services.  See 
the fishbowl proposal at dev.zope.org for more info.  Thus, the approach 
that Zope would do for web services might have some similarity to what 
you'd like to do.  Alternatively, take a look at the adapter for 
Ultraseek search engine at 
http://www.zope.org/Members/brianh/UltraseekDA.  It gives a model that 
might be useful to you.

3) Zope's approach of having separate objects that handle database 
connections provide the benefit that regular objects can't just fire up 
socket connections.  You want a model that helps prevent all of Zope's 
threads from being stuck waiting on responses to socket requests.

4) SQL Methods provide some useful and important machinery for your 
socket server approach.  First, I think you want site developers to 
think your thing is exactly the same as a regular SQL Method.  Also:

   - You likely want to keep the arguments list approach, to
   prevent people from inserting malicious data into the SQL requests.

   - Even more than with current database adapters, you want to
   retain the caching feature in SQL Methods.

   - Shoving the results into the Recordset code is something
   you might want to keep.

   - Etc.

Good luck, this looks like a useful project!

--Paul

StevenLee wrote:

> hi,all
> 
> I have got several questions here,and maybe you can give me some advice.
> 
> What I am trying to do  is write a product which can communicate with ODBC Socket Server,
> a win32 server application that allow applications to have access to Data Sources managed by Windows ODBC 
> DataSource Administrator. And now a class written in python can communicate with ODBC Socket Server.
> BTW,the class mentioned above  handles the connection to the server,sending SQL statement,and Receiving results.
> 
> As far as I know, in Zope,to access Data Sources,one must create a Database connection and  
> ZSQLMethods associated with it to get the results. (but I have doubt about this,
> IMHO,there must be some other way to do so,but what is it.).
> 
> Now,I am rather confused about how to solve the problem. 
> First,is what I need to write a DA? or just a common product?
> Second,if it's a DA, how can I use the existing class? I have read the article named "how to write a DA" in the how-tos,but it is quite abstract to me. 
> Third,where can I find more about the DataBase Connection and ZSQLMethod ? especially on how they work together to access databases.
> 
> OK,I am not sure whether I have made me understood, in fact,I am not quite clear myself. if you have any questions about that,I will reply ASAP.
> 
> thanks for your great patience,I will be grateful if you can give me some advice.
> thank you!
> 
> Best Wishes
> 
> yours sincerely
> Steven Lee  
> f?
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