seaside-dev June 2012

seaside-dev@lists.squeakfoundation.org

3 participants
4 discussions

cookie based sessions, RESTful urls no _k
by Nick Ager 22 Nov '12

22 Nov '12

Hi, In RESTful applications which also generate continuation key (_k) links a problem can arise if you open multiple tabs all sharing the same session. To illustrate: 1) Enable cookies for http://localhost:8080/examples/counter. 2) Open the counter and increment the value. 3) Open http://localhost:8080/examples/counter in a new tab and decrement the counter. 4) Return to the first counter and increment the value - you will see "-1" rather then "2" ! What I think is happening: If Seaside finds a session but there is no continuation key (_k) then WASession>>#handleFiltered: calls WARenderLoopMain>>#start which in turn creates a new root presenter and calls #initialRequest on the presenter. When the second tab is opened a new WACounter is created and stored in the session's #presenter property. When you return to the first tab, the callback is executed on the first counter, but the second counter is rendered. Ideas for possible fixes: * I thought that #presenter was backtracked so don't understand why the original counter #presenter isn't restored for the callback. If the presenter was backtracked correctly then the counter example should work as anticipated.... however: * in Pier (and potentially other RESTful apps) you don't want to create a new presenter for every RESTful call within an active session. If you don't create a new presenter then #initialRequest currently won't be called, which then won't allow your RESTful app to derive state from the url. If Seaside is modified to call #initialRequest do you need to differentiate between a call on a newly created session and one on an existing session? You could differentiate with a call to a new method on WAPresenter, pass in a flag to #initialRequest, or set a WARequestContext property to indicate a new session had been created. What to do with backtracked state. Do you nil all state before handling the request, restore state from a stored "initial value" snapshot or just use the state of the components from their last handled state? I bought this issue up before [1], but didn't pursue it as I was struggling to understand the issues and ran out of time. Julian responded to my previous email when I was proposing a problematic fix with: I'm not sure it's a good fix in the general case. If you don't have a > continuation key, you shouldn't (by definition) have any existing > (backtracked) state. Relying on the root presenter currently in the > Session is problematic since that value is backtracked for each > request; you'll simply get whichever root happened to be used by > whatever request was last handled by that session. If you don't happen > to be ever changing the root, then it may well be what you want, but > it's not right in the general case. > Incidentally, this also touches on the flaw I was discussing the other > week with our snapshots: because we have no continuation key, we > really ought to nil out any backtracked data before processing the > request (at least that way we have a consistent state while handling > the request). We don't run into the problem with the root presenter > because #start reinitializes it, but for other backtracked state, > you'd just get random stuff in there based on the last-handled > request. > A more appropriate general fix (at least in this case) could be to > take the last-used continuation and apply its state before handling a > request with no _k. However, we don't always know the last-used > (depending on the caching mechanism in place) and I'm not convinced > that is actually always what people want. I still feel pretty > confident that the "right" semantics of an Application/Session request > with no _k is to start a new main/render-loop. Certainly for Pier as it is currently designed I don't think that creating a new render-loop for session requests with the _k is the right thing to do, as it created a new root #presenter. I think ideally Seaside would for existing session with no _k 1) Keep the existing #presenter 2) call #initialRequest with a flag to indicate that a new session hadn't been created. 3) restore the state to an "initial render state" which is snapshotted (?) when the initial render occurs on a new session. Thoughts Nick [1] http://forum.world.st/sessions-continuation-keys-restful-urls-and-component… If each tabs starts with a RESTful url then a new presenter will be created.

3 4

Moving Seaside-REST from Addons to "Core" in 3.1
by Philippe Marschall 01 Jul '12

01 Jul '12

Hi I want to move Seaside-REST from Addons to the "Core" repository in Seaside 3.1: The reasons are the following: - the code base has stabilized and has been jürgenized by Lukas - we have documentation in the book [1] - several people use it I'm aware this will probably cause problems for some people but I don't think leaving it in addons or having it in both places are good alternatives either. Is this absolutely terrible or somebody (Dale?)? Personally I think of the addons repository as something similar to Apache Incubator. A place where we can experiment. If things turn out well we can graduate them to the core repository. [1] http://book.seaside.st/book/advanced/restful Cheers Philippe

4 6

Odd inconsistency in Seaside One-Click 3.0.7
by Lawson English 30 Jun '12

30 Jun '12

I was reviewing the Seaside book while refreshing my skills, and I noticed this very strange, trivial, but fundamental bug/inconsistency: http://www.youtube.com/watch?v=2RyREN00Nok (less than 2 minute demo). The issue is hardly worth mentioning, except for totally new users, but I DO wonder what is going on that changes the behavior from the first right-click on the category pane to the second. L -- Squeak from the very start (introduction to Squeak and Pharo Smalltalk for the (almost) complete and compleate beginner). https://www.youtube.com/playlist?list=PL6601A198DF14788D&feature=view_all

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review Grease stream hierarchy
by Philippe Marschall 25 Jun '12

25 Jun '12

Hi To fix issue 733 I had to introduce yet another stream wrapper (we would be so dead without Cog). And now our stream hierarchy is about to share the same fate as it's brethren. Here's what I did: We already had GRCodec stream which had about several responsibilities: - It defined "our" stream protocol and was an "anchor" for several packages (JavaScript, Comet, …) to add their class extensions - It was sort of a stream decorator base class that delegated to a concrete stream implementation - It was sort of abstract, #nextPutAll: and other methods had to be implemented and did not delegate (!). But #greaseNext:putAll:startingAt: did delegate. - It was the base class for codec streams although nothing codec related was there What I did I create a superclass named GRDelegatingStream, moved all the behavior there. GRCodecStream is now an (empty) abstract base class for coded stream. GRCountingStream and GRSwitchableStream are subclasses of GRDelegatingStream instead of GRCodecStream. I did no further clean up. All is not well in the state of Denmark tough. I outlined several smells in Issue 734 [1]. I would welcome it if somebody could review the current hierarchy and suggest improvements before it becomes big pile of mud. [1] http://code.google.com/p/seaside/issues/detail?id=734 Cheers Philippe

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seaside-dev June 2012