Has anyone successfully implemented this MSDN solution for Sharepoint External Libraries using Silverlight/WCF?

Question

Has anyone successfully implemented this MSDN solution for Sharepoint external libraries?

http://msdn.microsoft.com/en-us/library/dd440954.aspx

Some background: We will be providing file upload/download capabilities to both Intranet and Extranet users. In some cases, user uploads will be very large : sometimes twice the WSS3/MOSS2007 2GB limit. This MSDN solution looked compelling because we can leverage much of what Sharepoint has to offer - versioning, metadata, authentication, authorization, and workflow - but still manage very large files.

Here are some specific questions I have about the MSDN solution: 1. The architecture shows file uploads/downloads passing through asmx web services in Sharepoint. Wouldn't these asmx services load entire uploads into memory? 2. Security. How granular is it? Can individual files in the external library be assigned explicit permissions, or are permissions only set at the list level?

Answer 1

I've delved into the implementation. Here are some initial observations:

Although file uploads are initiated from Silverlight, the client-side Silverlight code does not break files into chunks before sending to the server. This means the entire file is sent across the wire at once. To support large uploads with this architecture, you'd need to implement something similar to the chunking concepts used in this CodePlex Silverlight File Upload control project. For better performance with large uploads, it may be necessary for the Silverlight component to point directly to the WCF service responsible for writing the streamed file to disk.

Files stored in the external repository are not natively tied to Sharepoint security. Rather, the security model is patterned after the repository. For the sake of simplicity, the sample code stores the repository security model in xml files. Theoretically, you may be able to replace the calls to xml files with calls to Sharepoint web services. This would (again, theoretically) give you both external file storage and Sharepoint context for authorization, versioning, etc.