Resource Abstraction Layer

Code is being refactored after an enlightening code review from my mentor -> thanks! :)

While that is being done (for the evaluation I think), I have also started halfway on a resource abstraction layer - that will allow the application to share resources from other sources (other than a filesystem).

A sample of the code below. I didn't want to make it too lengthy - but I've included path resolving and live properties (including etags and all the "dav" properties except the locking properties) as part of the abstraction layer, since it made sense to put them in. For example this could allow someone to share a database with tables as collections, records as resources and attributes as live properties of those resources. Thought I include the interface here as for comments.

All the code is commented (prefixed with #) since it seems blogger doesn't handle indentation well without something in front.

#class abstractionlayer(interface):

#   

#   def getResourceDescription(respath):

#      """ returns a string containing resource description, e.g. "File", "Directory" """

#

#   def getContentType(respath):

#      """ returns the MIME Content-Type for resource: mimetypes.guess_type() """

#   

#   def getLastModified(respath):

#      """ gets the Last Modified time (num of secs since epoch). Return 0 if not supported """

#   

#   def getContentLength(respath):

#      """ gets the content length of the resource """   

#   

#   def getEntityTag(respath):

#      """ gets the entity tag for specified resource """

#

#   def isCollection(respath):

#      """ tests if this is a collection : os.path.isdir """

#   

#   def isResource(respath):

#      """ tests if this is a non-collection resource : os.path.isfile """

#   

#   def exists(respath):

#      """ tests if this resource exists : os.path.exists """

#   

#   def createCollection(respath):

#      """ creates a collection : os.mkdir """

#   

#   def deleteCollection(respath):

#      """ deletes a collection : os.rmdir """

#   

#   def openResourceForRead(respath):

#      """ opens a resource for reading, returns stream """

#   

#   def openResourceForWrite(respath):

#      """ opens a resource for writing, returns stream """

#   

#   def deleteResource(respath):

#      """ deletes a resource : os.unlink """

#   

#   def copyResource(respath, destrespath):

#      """ copies a resource : shutils.copy2 """

#   

#   def getContainingCollection(respath):

#      """ returns the path of the collection containg the resource : os.path.dirname """

#   

#   def getContentsList(respath):

#      """ returns a list of names of resources in this collection

#          it is based on the assumption that names returned can be joinPath() with

#          the specified path to form the path to the resource

#          : os.listdir 

#      """

#

#   def joinPath(rescollectionpath, resname):

#      """ Joins the two path components intelligently : os.path.join """

#

#   def splitPath(respath):

#      """ Splits a path returning a tuple (containg collection path, #          resource name) : os.path.split 

#      """

#

#   def getProperty(respath, propertyname, propertyns):

#      """ returns property value for resource. This should implement all the required

#          webdav properties except locking properties 

#      """

#   

#   def isPropertySupported(respath, propertyname, propertyns):

#      """ tests if the specified property is a live property supported. If it is not

#          supported, the application will look for it in the dead properties library 

#      """

#   

#   def resolvePath(resheadpath, urlelementlist):

#      """ resolves the given url sequence to a path. Example:

#          the directory c:\Test was shared as http://localhost/testing/.

#          Then user accessing http://localhost/testing/dir1/dir2/file1.txt

#          will require resolvePath to return a valid path to file1.txt from

#          resolvePath('c:\Test', ['dir1','dir2','file1.txt'].

#          

#          An exception exiting this function may result in return of a 404 File Not Found

#      """