Sunday, July 05, 2009

Direct Access to Windows Live SkyDrive Files Has Weird Inconsistencies

This blog has used Windows Live SkyDrive for more than a year to insert Web-based *.png images into posts I write with Windows Live Writer. I’ve encountered no significant problems with specifying the direct access ID to files in a public folder, which appears in the address text box when you click an image selected from a folder:

or right-click the file icon for other than an image or *.txt file and choose Copy Shortcut:

I migrated image handling from a Flickr Professional account to GooglePages image storage because Flickr sent me a message that direct access to image files was a violation of its Terms of Service. GooglePages storage was inconvenient, so I moved storage and delivery to SkyDrive. SkyDrive’s Terms of Use had no restriction on direct file access that I could find. (The Terms of Use page appears to apply to most, if not all, Windows Live applications.)

Microsoft doesn’t offer a SkyDrive SDK.

Problems Accessing SkyDrive Files from a Windows Azure Service

My Windows Azure Blob Test Harness relies on *.bmp and *.zip files in a public SkyDrive folder as a data source for creating and displaying blobs. In this case, the user selects the file to upload to an Azure Blob from a list box:

Shortly after making the project available from Windows Azure in early 2009, I began to encounter HTTP 404 errors when attempting to add blobs from the second or third and higher items in the list. 

Following is part of the <asp:ListItem …> code in the Default.aspx page that shows some of the changes to the original direct access IDs that occurred overnight from 7/4/2009 to 7/5/2009 and cause 404 errors:


The items appear in the sequence in which I added them to the BlobFiles folder(s). Click here for a text file of the full ListItems (before and after).

What’s interesting about the unannounced changes to direct access IDs is the pattern of changed IDs:

  1. I can find no evidence that SkyDrive has changed the IDs of any files added to posts with Windows Live Writer.
  2. In some cases, changes occur to the second and later files added to the folder.
  3. Lately, changes occur to the third and later files added to the folder.

I’m in the process of testing other free storage solutions, such as DropBox and, which offer 2GB and 1GB free storage, respectively. Tests with DropBox indicate it doesn’t have SkyDrive’s 50MB file size limitation and solves the recent problem with failure to display a File Download Dialog for *.zip files from SkyDrive:

The last seven items (four BMPs and three ZIPs) are tests from DropBox storage into Development Storage; note the different Content Type values. This version is moving into Windows Azure production now.

An advantage of SkyDrive is its probable storage location—Microsoft’s US Northwest datacenter (Quincy, WA)—and thus good download performance to my Azure service. Tests show that DropBox is significantly slower than SkyDrive when upload blob files to Azure Blob Services.

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