Previous VRECI SharePoint site definitions, required the central system administrator of the SharePoint server farm to install and approve them, altering the security configuration of the system to allow them to run. This added an extra layer of bureaucracy, and required that the central system administrator was convinced that the extra code running on the server farm was not going to do any harm to that system. This is a huge burden, and unless the SharePoint system has been set up explicitly to host this particular site definition, this is not a risk that central system administrators are likely to take lightly.

There is another way to package up code for SharePoint that does not require the per-installation intervention of the central system administrator called a SharePoint Sandbox Solution. This is designed to enable code to be run on vanilla cloud-based SharePoint instances, where a standard SharePoint instance is provided as a hosted service. In these circumstances there is little chance that a user would be able to get the host to modify the underlying security settings to enable arbitrary user code to run.

These SharePoint Sandbox Solutions are analogous to apps which run on modern smart phones, users can upload them to their sites to enable them to run. To keep the central system administrators happy SharePoint Sandbox Solutions are heavily restricted in what they can do. See the MSDN article "Restrictions on Sandboxed Solutions in SharePoint 2010” for more details.

From the point of view of implementing a VRECI service using a SharePoint Sandbox Solution the following functionality is missing:

  • No calling native DLLs – this rules out the ITK libraries which previous versions has used
  • DLLs must have the AllowTrustedCallers attribute – this rules out the DeepZoomTools.DLL
  • No web-part connections – used to communicate the 'selected' image between components.

To resolve these issues the VRECI SharePoint Solution:

  • Uses a modified version of the mDCM library which is designed to run in the SharePoint Sandbox and has just enough functionality to get the image and the metadata from a DICOM file.
  • Has a built in generator which produces a minimally functional set of DeepZoom files from an image. So it does not need to link to DeepZoomTools.DLL
  • Built the selection of images into the Silverlight viewer, so that there is no need to communicate with external web-parts.

This means that the VRECI SharePoint Sandbox Solution can be run on cloud-based hosted SharePoint solutions.

Last edited Jan 24, 2012 at 9:33 PM by cancergrid, version 1


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