Application data management

Hi,

I am thinking of how application data is best persisted in squeak apps.
Probably I have problems in distinguishing the Squeak "platform" and  my
Application.

If I see my application as a part of squeak, then I guess there's no
need for custom resource management - as soon as a user does "save.."
all is saved automatically, including my app data (here its just a list
of filenames).

Is that the intended way? Or is "Save..." intended for developing only?
Gee squeak is really different.

Otherwise, I could do it all manually, persist my data to
somehomedir/.myappdata

How can I get the current user home?


Thanks for your comments.

Felix
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Hi,
filenames ?

The squeal image is a kind of cache. It can be used to save but it
shouldn't as not always reliable, threadsafe, etc...
There's plenty of option for persistence. One I tried recently is
Sandstone (in squeaksource), it's an active record like persistence
solution that save objects into files.

But there are plenty of persistence solution. Depends on your need.
>
> Is that the intended way? Or is "Save..." intended for developing only? Gee
> squeak is really different.
>
> Otherwise, I could do it all manually, persist my data to
> somehomedir/.myappdata

What kind of data ? records, objects...


>
> How can I get the current user home?

home directory ?  FileDirectory default


Cheers,

Cédrick
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On Thu, 10 Jul 2008 09:59:06 +0200
Felix Dorner <[hidden email]> wrote:

Well... that's referred to as "Image based persistence" :-). And yes, it is one way of persisting user's data. Some people here store lots of information in their images - presentations, stuff they type up, small prototype apps, etc. It's certainly not just for developers.

> Otherwise, I could do it all manually, persist my data to
> somehomedir/.myappdata

If you want to get serious, there are other options for persisting image data. Google for Magma and GOODS.

> How can I get the current user home?

Er... that's a hard one. I actually don't know. I'd probably start by installing the OSProcess package which might have something like that. I've had a quick look in my image and can't find anything.

Anybody else know?

Gulik.

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Michael van der Gulik <[hidden email]>
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Hi Cedric,
>> here its just a list of
>> filenames).
>>    
>
> filenames ?
>  
Hehe, Strings I should say...
> The squeal image is a kind of cache. It can be used to save but it
> shouldn't as not always reliable, threadsafe, etc...
> There's plenty of option for persistence. One I tried recently is
> Sandstone (in squeaksource), it's an active record like persistence
> solution that save objects into files.
>  

> What kind of data ? records, objects...
>
>  
What do you mean by a record? As I am currently just exploring the
Squeak world, i have no need for interchange, Objects would be fine if
that is the easiest.
> home directory ?  FileDirectory default
>  
Ok, thanks.
Felix

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In a deployed app I like to lock up the image and use class ReferenceStream (which is, for once, nicely documented) to write/read app data, or any of the availabe XML packages, if the app data is intended to be also processed by other non-Squeak apps.

Felix Dorner wrote

Hi,

I am thinking of how application data is best persisted in squeak apps.
Probably I have problems in distinguishing the Squeak "platform" and  my
Application.

If I see my application as a part of squeak, then I guess there's no
need for custom resource management - as soon as a user does "save.."
all is saved automatically, including my app data (here its just a list
of filenames).

Is that the intended way? Or is "Save..." intended for developing only?
Gee squeak is really different.

Otherwise, I could do it all manually, persist my data to
somehomedir/.myappdata

How can I get the current user home?


Thanks for your comments.

Felix
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Can you give one or two examples. Strings are not usual. I mean, it's
better not to store objects as string ;) Unless you need to read your
persistence backups, it's better to store with stuff like
ImageSegment, SmartRefStream (look at the in your image - class
comment)... But you've tools for that.

These posts could help: http://onsmalltalk.com/category/databases/

If objects, before using a proper OODB, have a look at that:
http://www.squeaksource.com/SandstoneDb

Cheers,

Cédrick


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Am 10.07.2008 um 09:59 schrieb Felix Dorner:

Typically a user would not save the image of an app. This is a dev-
time feature only.

> Otherwise, I could do it all manually, persist my data to  
> somehomedir/.myappdata
>
> How can I get the current user home?


There is no way in regular Squeak. You can use FFI or pass it from the  
script running your app.

The shining example for this is Sophie:

        http://www.sophieproject.org/

They have a Files-Locations package using FFI to find out about system-
specific directories for app data, documents, images, desktop etc.

- Bert -


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On Thursday 10 Jul 2008 2:21:18 pm cdrick wrote:
> > How can I get the current user home?
>
> home directory ?  FileDirectory default
There are multiple directory paths involved in Squeak;

1. Path where VM binary is located:
 SmalltalkImage current vmPath  "directory containing VM executable"

2. Path containing image file
        SmalltalkImage current imagePath "directory containing image"
        SmalltalkImage current imageName "full path of image file"

If you are running projects within a browser, the imageName is
$HOME/.npsqueak/SqueakPlugin.image"

3. Current working directory ("home" directory) is $SQUEAK_USERDIR.
       FileDirectory default
   If $SQUEAK_USERDIR is not set, this defaults to "My Squeak/" sub-directory
of the image directory. But if
    Preferences startInUntrustedDirectory
     is false, then it is set to the image path, a trusted directory.

4. Security keys are generated in the directory $SQUEAK_SECUREDIR or
in "secure/" sub-directory under the image directory.
      SecurityManager default

5. Lastly, loaded Projects are cached in  "Squeaklets/" sub-directory in
current working directory (even if the project files come from a local
path :-():
        Project squeakletDirectory

Hope this helps,
Subbu
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