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Re: [eclipse-incubator-e4-dev] E4 towards generic connection management (was: e4 beyond the ongoing UI conversations...)


Going back further, we had a different model again from what eventually appeared in Eclipse 1.0. In an earlier prototype, resources in the workspace were actually stubs for remote resources, with a UUID stored in the resource tree that could be used to fetch remote contents. The content of the remote resource would be lazily cached locally as needed. There are vestiges of this prototype in the current resource API, with methods such as IResource#isLocal/setLocal.  

As Kevin points out, one of the disadvantages of this model at the time was that it didn't interact well with external tools, since at any given time the local resource tree on disk could be empty or only semi-populated, and the external tools lacked the necessary hooks to invoke the IResource#setLocal call required to make the file or sub-tree appear in the local file system. However, there were also other disadvantages of this model. An obvious problem was lack of offline support. When you became unplugged from the network you could only work with the sub-set of resources already local. Also, by making local replication transparent there was no natural workflow for handling synchronization conflicts when multiple parties edited their local replicas of the remote resource concurrently. A final disadvantage was performance. The sparse local replica model worked great for browsing a large tree and selecting individual files to edit. However, when it came to "batch-processing" tasks that needed to traverse the entire tree, the entire workspace ended up being sucked down to the client anyway. In practice, the first time the user did a full build, or a workspace-level search, the entire remote tree had to be made local.

For these reasons we switched to a full replication model where the entire tree was always local, and the user performed explicit synchronization operations to synchronize with the remote resources.  This method supports offline editing well, has good performance characteristics, and has a clear model for handling and merging conflicting changes.  This model and some other remote development models are summed up here: http://www.eclipse.org/eclipse/platform-core/documents/2.0/remote-development.html.

I still think this local replication model is the best answer for a large number of development scenarios, and I wouldn't want to see it lost or compromised in e4. However, there are clearly several categories of development that are not well served this model, particularly in the areas of device development and mainframe development.  Here is one possible approach to addressing this in e4: rather than having a local workspace tree with resource stubs representing remote files, the entire workspace tree would reside on the remote system. An Eclipse instance on the remote system would be running a large portion of the traditional Eclipse "stack". Both the workspace tree and the UI model would live in this remote instance. The UI model would be replicated to the local workstation where it would be rendered either in a traditional-looking client with native widgets, or a browser (think X Windows).

My perhaps naive thinking is that it's much less expensive to replicate the UI model than the workspace, since the UI is typically only showing a small fraction of the workspace at any time. Tasks requiring intensive physical resource access such as search and build would run on the same remote machine as the workspace.  This would largely avoid having to reinvent the workspace and the massive eco-system of existing applications built on top of it.  It's true that since Eclipse has "taken over the world" the problem of integration with third party tools is not so great... the main challenge now is how e4 can interoperate with the "world" of plugins and apps built on the Eclipse 1.0 model.

John




Kevin McGuire/Ottawa/IBM@IBMCA
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08/24/2008 12:22 PM

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Re: [eclipse-incubator-e4-dev] E4 towards        generic        connection        management        (was: e4        beyond the ongoing UI conversations...)






Thanks Brian!


Stepping back a minute:


An initial fundamental decision we made way-back-when on Eclipse was that we'd be file system based.  It seemed the best way to ensure we could interoperate with non-Eclipse based applications, with the file system being the one thing in common.


Personally, I'm not sure that's so compelling anymore.  At the time, it was a world where there'd be a small number of Eclipse plugins trying to work with a huge amount of pre-existing applications.  The only way to work together is via the file system. So it was probably the right decision then.  But now that Eclipse has taken over the world <grin>, I don't think the scenarios still match.


Today the interesting scenarios are around data sharing, data syncing, remote access, remote computation, remote services ... that's the current pain point of interoperability.  I'm talking more than just common shared components for the transports and services (obviously an important pre-requisite), but rather a deep integration with what it means to be a resource.  Things like: you can't assume they're local, you can have a tremendous number of them, maybe each IResource has both a local storage and a remote URI, treating local storage as a cache, keeping track of sync state, transparently accessing the transports...


So take the Eclipse 1.0 thinking and replace "file system" with "network".  Maybe *this* is what the E4 platform needs to be.


Easier said then done though. The existing code is tied to the a file system based resource model with many subtle assumptions which complicate even more the problem of backwards compatibility of API and behaviour.


Nonetheless, I do believe that a rethinking of our resource model, with the view to remote data interop, could be the fundamental shift for E4 and is probably what we need to do to have any kind of forward thinking desktop presence.  It is however a ton of work (Jeff McAffer and John Arthorne will I'm sure attest to that).


Regards,

Kevin





brian.fitzpatrick@xxxxxxxxxx
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08/22/2008 11:42 AM

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Re: [eclipse-incubator-e4-dev] E4 towards generic        connection        management        (was: e4 beyond the ongoing UI conversations...)








Hey Kevin!


Those are definitely some cool ideas!

I think using URIs to map to remote resources (or local ones even) would give us a ton of flexibility, but would definitely present some interesting challenges. And the whole idea of remote servers and resources playing into a common UI for users (or multiple common UIs, all with a similar look and feel) would fit into our discussions nicely.

A "cloud" of Eclipse plug-ins and resources all accessible through a common UI. What a concept. :)


--Fitz


Brian Fitzpatrick
Eclipse Data Tools Platform PMC Chair
Eclipse Data Tools Platform Connectivity Team Lead
Staff Software Engineer, Sybase, Inc.


Kevin McGuire <Kevin_McGuire@xxxxxxxxxx>
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08/22/2008 09:31 AM

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Re: [eclipse-incubator-e4-dev] E4 towards generic connection        management        (was: e4 beyond the ongoing UI conversations...)










Hi gang,


> I fully agree that in a world where the "Network" is becoming more

> important than the local client, a generic approach for the user to

> manage connections of all kinds will simplify user experience

> (and help reducing code duplication and bloat).


About a year ago I was looking into an area they were terming "WebOS".  The notion was that for rich applications, you need some kind of lightweight platform pre-installed on the desktop from which you could serve up applications written against it (presumably in JS or PHP or whatever).  One platform service was of course a communication framework, since generally some or all of your data is going to be on the server. This included synchronization as a first class platform service so you can treat the local storage as a cache or offline access. There were a number of players in this area (approx. 4-5 companies).  I don't the current state.


At the time, my reaction was, "Hmm, we could be one of those!". We essentially have all the components they talked about, though not integrated to the same degree, and with p2 we have a first class provisioning route.


I view this issue as being intimately tied to the flexible resource model topic. For real data mobility, instead of assuming that resources map to files as we do now, we should assume they map to URIs, served up from anywhere (e.g. a MySQL database), with local proxies providing anything from summary information (name, size), enough say for navigation, to the full contents for editing purposes. Current desktop services such as Search then need to be changed since the number of resource can be huge, and searchable content could be remote.


So this is a very different notion of "the platform" than what we have now. A pretty cool one though!


There a more thoughts squirreled away in my brain somewhere ...


Regards,
Kevin "Not Just About Pretty UIs" McGuire_______________________________________________
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