Embedded Magma database

[Jerry Bell]

My understanding of Magma so far is very superficial, there is a lot  
of 'magic' happening right now.  I'm sure that will change as I get  
more experience with the system.  I've only seen the error I described  
a couple of times so far but I wanted to make sure I could handle it  
in a headless application, if it was not handled already.

I have not worked in Squeak very much, and  I've never seen that  
warning idiom.  It looks simple enough.  But, I'm using the Magma  
seasideHelper (specifically, I'm using WAMagmaSoloAuto.) , so I'm not  
sure where to put the warning handlers.   Any suggestions are welcome!

I believe I'd prefer to have my image start from a clean state with no  
existing Magma sessions.   I believe that is happening now, but I'm  
not sure.   I don't save the server image, I always either quit  
without saving the image, or the server might possibly be shutdown  
"dirty" without any warning.

Another question: I have a few "long running" operations which should  
be triggered from the web application, but which should run in their  
own background process without blocking the web interface.  For  
example, I generate RSS feeds for some of my database contents.   
What's the best way to handle this?   Currently i make a deepCopy of  
my target object, and fork the operation as a separate process with  
that copy.   If I need to access the database in that forked process,  
I use

(WAMagma forApp: 'appName') rootAs: MyServerRoot

Without the deepCopy, I believe I was attempting to access a Magma  
proxy outside of the Seaside session, and I would sometimes get magma  
proxy errors.

I think it might be better if I passed the unique ID of my target  
object to the new process, and let it use that ID to find the target  
object and access everything from the database through "direct access"  
instead of using a deepCopy.

Also, how should I handle the "direct access"?  Is it ok to do a

myDB := (WAMagma forApp: 'appName') rootAs: MyServerRoot

the first time I need it, and then use it over and over again?  If so,  
do I need to do an abortSession on it from time to time to keep it up  
to date with changes from the web interface?  Perhaps I should do an  
abortSession before each time I use it?   Do I need to do anything to  
close that session when the Squeak image quits?

Thanks,

Jerry








On Sep 14, 2008, at 11:04 AM, Chris Muller wrote:

> After more thinking, there is a (fairly common!) scenario where
> developers will not feel the need to wrap the MagmaServerConsole in
> their own application-server wrapper.  In other words, just a plain
> vanilla Magma server image.
>
> In these cases, a Magma server image is simply saved and exited while
> its running, and this can even be performed remotely ("mySession
> serverSaveAndExit").
>
> Under this case, when the server image is restarted, only Magma's own
> startUp: code re-establishes the files and sockets, your application
> code will not have the opportunity to handle any warnings if there are
> any.
>
> I will fix that..
>
> - Chris
>
>
> On Fri, Sep 12, 2008 at 7:12 PM, Chris Muller <asqueaker at gmail.com>  
> wrote:
>> Hi Jerry, yes Magma may signal warnings which you will need to handle
>> if you want to run headless.  Are you familiar with handling
>> exceptions in Squeak?  Here is the pattern:
>>
>> [ ..do some squeak code.. ]
>>   on: Warning
>>   do:
>>       [ : warning |
>>       ..log the warning somewhere if you want...
>>       warning resume ]
>>
>> Honestly, I'm curious why you would be receiving that particular  
>> warning..
>>
>>
>>
>> On Fri, Sep 12, 2008 at 4:15 PM, Jerry Bell <jdbell at oxfordmetamedia.com 
>> > wrote:
>>> Hi,
>>>
>>> I'm building a simple web application with an embedded Magma  
>>> database which
>>> will run on a headless Linux appliance.
>>>
>>> A few times while developing the system, I've had a dialog window  
>>> when
>>> starting Squeak which has asked me to OK a recovery of the Magma  
>>> database.
>>>
>>> Obviously I won't have a UI on this headless appliance.  What do I  
>>> need to
>>> do to make sure all of those types of interaction are handled by my
>>> application?
>>>
>>> Thanks,
>>>
>>> Jerry
>>>
>>>
>>> _______________________________________________
>>> Magma mailing list
>>> Magma at lists.squeakfoundation.org
>>> http://lists.squeakfoundation.org/mailman/listinfo/magma
>>>
>>