Simple Sharing Extensions (SSE) for .NET

Source code checked in, #69709

Project Collection Service Accounts — Mon, 01 Oct 2012 22:10:56 GMT

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Source code checked in, #69708

Project Collection Service Accounts — Mon, 01 Oct 2012 22:06:45 GMT

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Source code checked in, #52373

_TFSSERVICE — Wed, 28 Jul 2010 17:08:20 GMT

Checked in by server upgrade

Updated Wiki: Home

dcazzulino — Sat, 17 Jul 2010 17:51:18 GMT

Project Description
SSE is an XML micro-format and corresponding sync algorithm that can be embedded in RSS or Atom feeds to allow for two-way synchronization among peers. More important: the algorithm allows for mesh-style synchronization between nodes, with no concept of a "master" copy. This can be game-changing for data-exchange and app-level data interop. But only the future will tell.

This projects provides an open-source implementation of the required behavior from the spec.

SSE was initially announced by Ray Ozzie (Microsoft's CTO). You can learn more about SSE by watching the MSDN TV video and reading the latest SSE spec and links above.

The library has 80%+ code coverage through unit tests.

What can you do with the library right now?

Create an adapter (repository) that talks to your underlying application data/business objects (your CRM system, data-entry app, whatever)
Export RSS feeds with synchronization information embeeded for merging with other feeds
Import RSS feeds from other peers
Synchronize a local feed via HTTP with a server feed
Do all this without changing any code in your app: this makes for a hassle-free way to add import/export/sync functionality to your application

The SSE spec takes care of defining a standard algorithm for detecting conflicts and updates in a merge operation, as well as the behavior for deleted and created items. This makes for a predictable behavior regardless of the actual implementation technology.

The library was created with the following goals in mind:

Have a minimal library that can be easily extended with adapters to accomodate simple synchronization scenarios
Provide a full .NET as well as .NET Compact Framework implementation
Interop with other SSE implementations as they come along

The following are non-goals:

Provide a full-blown and highly optimized synchronization engine (i.e., you can hardly use it for full database merge/replication, complex data/binary payload sync, etc.)
Provide a server-side story
Provide a service to periodically perform sync with a server and manage jobs (this means you have to manually sync from your app using the exposed SyncEngine API)

Included in the download is a sample application that is a very simple Customer CRUD application that provides a custom adapter to import/export feeds using its internal data-access component, and which syncs with a simple ASMX webservice via HTTP. This sample application uses a SQL Compact Edition database, so you'll need to install it, as well as the SQL Compact Edition Tools for VS 2005. If you don't want to, just exclude the Samples solution folder from the solution.

*Download it now!

Thanks John Crowley for dreaming up such a cool logo for SSE!

This project is sponsored by Clarius Labs.
This project is owned by the MVPXML Project.

Commented Issue: Bugs found in MergeItems()

dcazzulino — Mon, 27 Apr 2009 14:00:58 GMT

It looks like the actual issue is because of the null test for W as shown below. The test should check if there are no conflicts and if W is subsumed by localItem – this will handle the case when the localItem and incomingItem are the same item, such that MergeOperation.None is returned.

private MergeOperation MergeItems(Item localItem, Item incomingItem, out Item proposedItem)
{
Tracer.TraceData(this, TraceEventType.Verbose, "Applying SSE merge algorithm");
proposedItem = null;

//3.3.2
List<Item> L = new List<Item>();
L.AddRange(localItem.Sync.Conflicts);
localItem.Sync.Conflicts.Clear();
L.Add(localItem);

//3.3.3
List<Item> I = new List<Item>();
I.AddRange(incomingItem.Sync.Conflicts);
incomingItem.Sync.Conflicts.Clear();
I.Add(incomingItem);

//3.3.4
List<Item> M = new List<Item>();

//3.3.5
Item W = null;

//3.3.6 and 3.3.7
PerformStep7(ref L, ref I, M, ref W);
//3.3.8
PerformStep7(ref I, ref L, M, ref W);
// ****HERE****
if (W == null)
{
//There is no need to update the local item
return MergeOperation.None;
}

proposedItem = W;

//3.3.10
if (!W.Sync.NoConflicts)
{
//3.3.11
foreach (Item z in M)
{
if (!z.Equals(W) && !W.Sync.Conflicts.Contains(z))
{
W.Sync.Conflicts.Add(z);
}
}
}

if (W.Sync.Conflicts.Count > 0)
{
return MergeOperation.Conflict;
}
else
{
return MergeOperation.Updated;
}
}

Proposed Solution: Change the highlighted code to ‘if ((W == null) || ((M.Count == 1) && W.IsSubsumedBy(localItem)))’
Comments: ** Comment from web user: dcazzulino **

Can you please provide a test that asserts what's the expected output from the public API?
Without a failed unit test that showcases how the current logic is broken, we can't really take action on it as-is.

Created Issue: Bug found in UpdateSyncIfItemHashChanged()

psuthar — Mon, 20 Apr 2009 16:04:35 GMT

This bug is in CompoundRepository.cs::UpdateSyncIfItemHashChanged(). The call to update the repository is using the old sync value which means that the wrong metadata for an updated item is retained.

private Sync UpdateSyncIfItemHashChanged(IXmlItem item, Sync sync)
{
// TODO: check if this is correct.
if (item.Tag.ToString() != sync.Tag.ToString())
{
Tracer.TraceData(this, TraceEventType.Verbose, "Updating Sync for Item with ID {0} - Original Tag {1} / Current Tag {2}", sync.Id, sync.Tag, item.Tag);

Sync updated = Behaviors.Update(sync,
DeviceAuthor.Current,
DateTime.Now, sync.Deleted);
// **************HERE********************
sync.Tag = item.Tag;
// **************HERE********************
syncRepo.Save(sync);

return updated;
}

return sync;
}

Proposed Solution: Change the highlighted ‘sync’ references to ‘updated’.

Created Issue: Bugs found in MergeItems()

psuthar — Mon, 20 Apr 2009 16:02:53 GMT

Updated Release: SimpleSharing.NET 1.0 (Feb 11, 2008)

pcibraro — Mon, 09 Feb 2009 18:09:44 GMT

This release supports the final feedsync specification (1.0)

Highlights:

Compliance with final FeedSync 1.0 spec version.
Support for item filters at adapter and SyncEngine level.
Refactored database adapter to use hidden tables for sync metadata.
Several bug corrections

Released: SimpleSharing.NET 1.0 (Feb 11, 2008)

Mon, 09 Feb 2009 18:09:44 GMT

This release supports the final feedsync specification (1.0)

Highlights:

Compliance with final FeedSync 1.0 spec version.
Support for item filters at adapter and SyncEngine level.
Refactored database adapter to use hidden tables for sync metadata.
Several bug corrections

Source code checked in, #30678

dcazzulino — Mon, 26 Jan 2009 18:21:13 GMT

Preparation for interim release adding support for feedsync 1.0.1 spec review (datetimes are adjusted to UTC always). Temporarily removed CF support (moving to mesh4x.org).

Source code checked in, #30593

dcazzulino — Sat, 24 Jan 2009 20:56:48 GMT

Preparation for interim release adding support for feedsync 1.0.1 spec review (datetimes are adjusted to UTC always). Temporarily removed CF support (moving to mesh4x.org).

Source code checked in, #30590

dcazzulino — Sat, 24 Jan 2009 20:35:21 GMT

retiring vs2005 version

Source code checked in, #30589

dcazzulino — Sat, 24 Jan 2009 20:34:17 GMT

Retiring vs2005 support

Created Issue: Generalize processing of feeds so that any element with is parsed

psuthar — Tue, 18 Nov 2008 17:29:09 GMT

Right now the implementation only sees <item> elements with a <sx:sync> element as valid items. Since any element can syncable, it would be helpful if the implementation were changed to either include all elements with a <sx:sync> subelement as part of the Items collection, or to have an Items collection for <item> elements and SyncableItems collection for all syncable elements.

Reviewed: SimpleSharing.NET 1.0 (Oct 24, 2008)

markry — Sat, 25 Oct 2008 02:25:27 GMT

Rated 5 Stars (out of 5) - The simplicity of this idea may cause some people to dismiss it. But IMHO it is ground-breaking and awesome.

Reviewed: SimpleSharing.NET 1.0 (Oct 24, 2008)

markry — Sat, 25 Oct 2008 02:25:23 GMT

Rated 5 Stars (out of 5) - The simplicity of this idea may cause some people to dismiss it. But IMHO it is ground-breaking and awesome.

UPDATED RELEASE: SimpleSharing.NET 1.0 (Jan 22, 2008)

Tue, 29 Apr 2008 19:00:55 GMT

This release supports the final feedsync specification (1.0)

Highlights:

* Compliance with final FeedSync 1.0 spec version.
* Support for item filters at adapter and SyncEngine level.
* Refactored database adapter to use hidden tables for sync metadata.
* Several bug corrections

Source code checked in

pcibraro — Tue, 29 Apr 2008 18:30:14 GMT

New drop 1.1.0.0

Source code checked in

pcibraro — Tue, 29 Apr 2008 18:28:15 GMT

Updated assembly version

Source code checked in

pcibraro — Fri, 25 Apr 2008 19:40:51 GMT

Replaced _SSE by _FeedSync