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Re: A session-aware kind of FileLibrary - how/where to start

Posted by jtuchel on Mar 30, 2021; 12:56pm
URL: https://forum.world.st/A-session-aware-kind-of-FileLibrary-how-where-to-start-tp5128139p5128146.html

Hi Karsten,


thanks for your ideas. This needs a little bit of fiddling and tweaking, but I think I found something that seems to work. I am not sure if this is going to break something, but it does what I want...

I am not sure if this is a good approach, but maybe somebody wants to comment on it:
  • Create a Subclass of WARequestHandler
  • Add an inst var @app and accessors to it
  • In the method where the root component et al. are registered with WAAdmin do: 
    •     attachmentsHandler := WAAdmin register: OfAttachmentsHandler at: 'att'.
          attachmentsHandler app: app.
  • In the handler's handleFiltered: method I do:
    • handleFiltered: aRequestContext
          | fName user |
          user := (self app sessions
              detect: [:s | s key = (aRequestContext request queryFields at: '_s' ifAbsent: [nil])]
              ifNone: [^nil])
                  user.
    • ...

Does this look like a workable solution? If so, is there a nicer way of searching for a session?

Bonus question:

... forget this one, Esteban just answered it in another answer and even answered the question about the nicer way of searching for the session ;-)



Joachim







Am 30.03.21 um 12:34 schrieb Karsten Kusche:
Hi Joachim,

the session idea is handled and added by the applications. When a request is dispatched to the application, it „somehow“ reads the session information (typically via _s parameter). Then it can find out the session object using its cache object, where the _s parameter happens to be a key.

If you want your file library to only respond to certain files in a certain session, you can transport the session-key in your url…maybe also as _s parameter. Then in your file-handler or in your file library you can take that parameter, ask the appropriate application (either always the same application or you pass the application name as another parameter) for the session and go from there.

Another alternative is that you simply use your sessions continuation registry and register the file there. I think <img> and <a> tags can both be fed with Document objects that are responded when needed. That way your files would be accessible via /blah/_s=123&_k=34324, which your apache will pass through anyway.

Kind Regards
Karsten

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Am 30. März 2021 um 12:11:22, [hidden email] ([hidden email]) schrieb:

Hi Sven,

I started with a WAFileLibrary subclass first. I couldn't get it to work the way I wanted.

One of the problems is that all FileLibraries added by addLibrary: end up as an endpoint in the /files path, unless I also register a WAFileHandler (subclass) at another endpoint. In my case, I'd like to separate things: /files is for "public" files, and then there should be /attachments for "private" stuff of my users. AFAIK there is no way to register an additional File Library in another path/endpoint then /files, or is there? (this really is a question, not an argument...). Why do I want that? Because I want to keep the configuration of the frontend web server (Apache in my case) simple. Redirecting all requests of /files and subdirectories to some folder is easy. Not sure whether redirecting all but one is just as easy...?

The other one is that a WAFileLibrary subclass doesn't know its session either. As an experimented I added this override to one of my FileLibraries:
handle: aRequestContext
   self session ifNotNil: [:s| s halt].
   super handle: aRequestContext

And it never halts. This makes some sense, because in order to save files, you don't need a session. Anybody can have these files. And that is what I don't want for some files...

So I started subclassing WAFileHandler and found out a FileHandler doesn't know the session either . But I want to have access to the logged-ob user in the session. So it seems I either have to subclass from something else or add "something" to my WAFileHandler in the Application configuration, like a Filter or whetever...

So either I need to know something more about FileLibraries (register at something else than /files, make them session aware) or FileLibrary is not what I  have to subclass...

Any more ideas?

Joachim






Am 30.03.21 um 11:51 schrieb Sven Van Caekenberghe:
Hi Joachim,

I would try to look at WAFileHandler, which is responsible for serving the files.

It seems to delegate most work to WAFileLibrary>>#handle:

Maybe you can subclass WAFileLibrary (insert your superclass before your concrete class) to check the session for a login.

Sven


On 30 Mar 2021, at 11:18, [hidden email] wrote:

Hi,


There are situations in which I feel like after 10+ years of using Seaside, I am still a newbie. (well, same for Smalltalk after 25+ years, so this may be normal).

I would like to implement some kind of FileLibrary that is aware of the current session and only delivers files to logged-on users.

It seems like the best starting point for this is to subclass WARequestHandler and register it with WAAdmin. So the first thing I did was implement handleFiltered: aRequestContext. Unfortunately, neither aRequestContext nor self return a WASession, although I entered _s and _k form a logged in session into the address bar of my Browser. This may be a naive approach, but as a fist test case this seemed like a good idea ;-)

Now the question I ask myself is: how do I teach my WARequestHandler subclass the trick of knowing/finding the current session. Do I add some Filter? Is subclassing WARequestHandler the wrong idea anyways? (I started my experiments with a subclass of WAFileLibrary, but that also didn't get me anywhere...).

I am not asking for a ready-made solution. I'd rather try to understand a little more about Seasides innards here...

Any pointers? Kick-off ideas what to look at?


tia,


Joachim




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