-Modified interface of convertable to add new method that only returns

the authorized formats for conversion.
-Implement mixin for convertable, text_convertable,base_convertable,
html_convertable, metadata_discoverable and document



git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@34090 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/interfaces/convertable.py

@@ -109,3 +109,10 @@ class IConvertable(Interface):
     where format is an extension (ex. 'png') which can be 
     passed to IConvertable.convert or to IDownloadable.index_html
     """
+  def getPermittedTargetFormatItemList():
+    """
+    Returns the list of authorized formats for conversion
+    in the form of tuples. For each format, checks
+    if the current user can convert the current 
+    document into that format.
+    """
\ No newline at end of file

product/ERP5/mixin/base_convertable.py

+# -*- coding: utf-8 -*-
+##############################################################################
+#
+# Copyright (c) 2009 Nexedi SA and Contributors. All Rights Reserved.
+#                    Jean-Paul Smets-Solanes <jp@nexedi.com>
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# garantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+#
+##############################################################################
+
+import md5
+import string
+import xmlrpclib, base64, re, zipfile, cStringIO
+from xmlrpclib import Fault
+from xmlrpclib import Transport
+from xmlrpclib import SafeTransport
+from Acquisition import aq_base
+from AccessControl import ClassSecurityInfo
+from Products.ERP5Type import Permissions
+from Products.CMFCore.utils import getToolByName
+from Products.ERP5Type.Cache import DEFAULT_CACHE_SCOPE
+from Products.ERP5Type.Base import WorkflowMethod
+from zLOG import LOG
+from Products.ERP5Type.Cache import CachingMethod
+
+# Mixin import
+from Products.ERP5.mixin.convertable import ConvertableMixin
+
+
+
+
+class BaseConvertableMixin:
+  """
+  This class provides a generic implementation of IBaseConvertable.
+
+  """
+
+  # Declarative security
+  security = ClassSecurityInfo()
+
+
+  # Declarative security
+  security = ClassSecurityInfo()
+  security.declareObjectProtected(Permissions.AccessContentsInformation)
+  
+
+
+  security.declareProtected(Permissions.AccessContentsInformation, 'hasBaseData')
+  def hasBaseData(self):
+    """
+        A TextDocument store its data in the "text_content" property. Since
+        there is no such thing as base_data in TextDocument, having base_data
+        is equivalent to having some text_content.
+    """
+    return self.hasTextContent()
+
+  def convertFile(self, **kw): # XXX - It it really useful to explicitly define ?
+    """
+    Workflow transition invoked when conversion occurs.
+    """
+  convertFile = WorkflowMethod(convertFile)
+
+  security.declareProtected(Permissions.ModifyPortalContent, 'convertToBaseFormat')
+  def convertToBaseFormat(self, **kw):
+    """
+      Converts the content of the document to a base format
+      which is later used for all conversions. This method
+      is common to all kinds of documents and handles
+      exceptions in a unified way.
+
+      Implementation is delegated to _convertToBaseFormat which
+      must be overloaded by subclasses of Document which
+      need a base format.
+
+      convertToBaseFormat is called upon file upload, document
+      ingestion by the processing_status_workflow.
+
+      NOTE: the data of the base format conversion should be stored
+      using the base_data property. Refer to Document.py propertysheet.
+      Use accessors (getBaseData, setBaseData, hasBaseData, etc.)
+    """
+    if getattr(self, 'hasData', None) is not None and not self.hasData():
+      # Empty document cannot be converted
+      return
+    try:
+      message = self._convertToBaseFormat() # Call implemetation method
+      self.clearConversionCache() # Conversion cache is now invalid
+      if message is None:
+        # XXX Need to translate.
+        message = 'Converted to %s.' % self.getBaseContentType()
+      self.convertFile(comment=message) # Invoke workflow method
+    except NotImplementedError:
+      message = ''
+    return message
+
+  def _convertToBaseFormat(self):
+    """
+    """
+    raise NotImplementedError
+
+  security.declareProtected(Permissions.AccessContentsInformation,
+                            'getMetadataMappingDict')
+  def getMetadataMappingDict(self):
+    """
+    Return a dict of metadata mapping used to update base metadata of the
+    document
+    """
+    try:
+      method = self._getTypeBasedMethod('getMetadataMappingDict')
+    except KeyError, AttributeError:
+      method = None
+    if method is not None:
+      return method()
+    else:
+      return {}
+  
+  security.declareProtected(Permissions.ModifyPortalContent, 'updateBaseMetadata')
+  def updateBaseMetadata(self, **kw):
+    """
+    Update the base format data with the latest properties entered
+    by the user. For example, if title is changed in ERP5 interface,
+    the base format file should be updated accordingly.
+
+    Default implementation does nothing. Refer to OOoDocument class
+    for an example of implementation.
+    """
+    pass  
\ No newline at end of file

product/ERP5/mixin/convertable.py

+# -*- coding: utf-8 -*-
+##############################################################################
+#
+# Copyright (c) 2009 Nexedi SA and Contributors. All Rights Reserved.
+#                    Jean-Paul Smets-Solanes <jp@nexedi.com>
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# garantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+#
+##############################################################################
+
+import md5
+import string
+import xmlrpclib, base64, re, zipfile, cStringIO
+from xmlrpclib import Fault
+from xmlrpclib import Transport
+from xmlrpclib import SafeTransport
+from Acquisition import aq_base
+from AccessControl import ClassSecurityInfo
+from Products.ERP5Type import Permissions
+from Products.CMFCore.utils import getToolByName
+from Products.ERP5Type.Cache import DEFAULT_CACHE_SCOPE
+from Products.ERP5Type.Base import WorkflowMethod
+from zLOG import LOG
+from Products.ERP5Type.Cache import CachingMethod
+
+
+
+def makeSortedTuple(kw):
+  items = kw.items()
+  items.sort()
+  return tuple(items)
+
+
+class ConvertableMixin:
+  """
+  This class provides a generic implementation of IConvertable.
+
+    This class provides a generic API to store in the ZODB
+    various converted versions of a file or of a string.
+
+    Versions are stored in dictionaries; the class stores also
+    generation time of every format and its mime-type string.
+    Format can be a string or a tuple (e.g. format, resolution).
+  """
+
+  # Declarative security
+  security = ClassSecurityInfo()
+
+
+  # Declarative security
+  security = ClassSecurityInfo()
+  security.declareObjectProtected(Permissions.AccessContentsInformation)
+  
+  # Conversion methods
+  security.declareProtected(Permissions.AccessContentsInformation, 'convert')
+  def convert(self, format, **kw):
+    """
+      Main content conversion function, returns result which should
+      be returned and stored in cache.
+      format - the format specied in the form of an extension
+      string (ex. jpeg, html, text, txt, etc.)
+      **kw can be various things - e.g. resolution
+
+      Default implementation returns an empty string (html, text)
+      or raises an error.
+
+      TODO:
+      - implement guards API so that conversion to certain
+        formats require certain permission
+    """
+    # Raise an error if the format is not permitted
+    if not self.isTargetFormatPermitted(format):
+      raise Unauthorized("User does not have enough permission to access document"
+	      " in %s format" % (format or 'original'))
+    if format == 'html':
+      return 'text/html', '' # XXX - Why ?
+    if format in ('text', 'txt'):
+      return 'text/plain', '' # XXX - Why ?
+    raise NotImplementedError
+   
+  security.declareProtected(Permissions.View,'isTargetFormatAllowed')
+  def isTargetFormatAllowed(self,format):
+    """
+    Checks if the current document can be converted
+    to the specified target format.
+
+    format -- the target conversion format specified either as an
+              extension (ex. 'png') or as a mime type
+              string (ex. 'text/plain')
+    """
+    return format in self.getTargetFormatList()
+
+
+  security.declareProtected(Permissions.View,'isTargetFormatPermitted')
+  def isTargetFormatPermitted(self, format):
+    """
+      Checks if the current user can convert the current document
+      into the specified target format.
+    """
+    method = self._getTypeBasedMethod('isTargetFormatPermitted', 
+                 fallback_script_id='Document_isTargetFormatPermitted')
+    return method(format)
+  
+  security.declareProtected(Permissions.View,'getTargetFormatItemList') 
+  def getTargetFormatItemList(self):
+    """
+    Returns the list of acceptable formats for conversion
+    in the form of tuples which can be used for example for
+    listfield in ERP5Form. Each tuple in the list has the form
+    (title, format) where format is an extension (ex. 'png')
+    which can be passed to IConvertable.convert or to 
+    IDownloadable.index_html and title is a string which 
+    can be translated and displayed to the user.
+ 
+    Example of result:    
+        [('ODF Drawing', 'odg'), ('ODF Drawing Template', 'otg'), 
+        ('OpenOffice.org 1.0 Drawing', 'sxd')]
+    """
+    return self.getAllowedTargetItemList()
+
+  security.declareProtected(Permissions.View,'getTargetFormatTitleList')
+  def getTargetFormatTitleList(self):
+    """
+    Returns the list of titles of acceptable formats for conversion 
+    as a list of strings which can be translated and displayed 
+    to the user.
+    """
+    return map(lambda x: x[0], self.getTargetFormatItemList())
+
+  security.declareProtected(Permissions.View,'getTargetFormatList')
+  def getTargetFormatList(self):
+    """
+    Returns the list of acceptable formats for conversion
+    where format is an extension (ex. 'png') which can be 
+    passed to IConvertable.convert or to IDownloadable.index_html
+    """
+    return map(lambda x: x[1], self.getTargetFormatItemList())
+  
+  security.declareProtected(Permissions.View,'getPermittedTargetFormatItemList') 
+  def getPermittedTargetFormatItemList(self):
+    """
+    Returns the list of authorized formats for conversion
+    in the form of tuples. For each format, checks
+    if the current user can convert the current 
+    document into that format.
+ 
+    """
+    authorized_format_list = []
+    format_list = self.getTargetFormatItemList()
+    for format in format_list:
+      if self.isTargetFormatPermitted(format[1]):
+       authorized_format_list.append(format)
+    return authorized_format_list
\ No newline at end of file

product/ERP5/mixin/document.py

+# -*- coding: utf-8 -*-
+##############################################################################
+#
+# Copyright (c) 2009 Nexedi SA and Contributors. All Rights Reserved.
+#                    Jean-Paul Smets-Solanes <jp@nexedi.com>
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# garantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+#
+##############################################################################
+
+import md5
+import string
+import xmlrpclib, base64, re, zipfile, cStringIO
+from xmlrpclib import Fault
+from xmlrpclib import Transport
+from xmlrpclib import SafeTransport
+from Acquisition import aq_base
+from AccessControl import ClassSecurityInfo
+from Products.ERP5Type import Permissions
+from Products.CMFCore.utils import getToolByName
+from Products.ERP5Type.Cache import DEFAULT_CACHE_SCOPE
+from Products.ERP5Type.Base import WorkflowMethod
+from zLOG import LOG
+from Products.ERP5Type.Cache import CachingMethod
+
+#Mixin import
+from Products.ERP5.mixin.convertable import ConvertableMixin
+from Products.ERP5.mixin.cached_convertable import CachedConvertableMixin
+
+class DocumentMixin(ConvertableMixin, CachedConvertableMixin):
+  """
+  This class provides a generic implementation of IDocument.
+  """
+
+  # Declarative security
+  security = ClassSecurityInfo()
+
+
+  # Declarative security
+  security = ClassSecurityInfo()
+  security.declareObjectProtected(Permissions.AccessContentsInformation)
+  
+
+  security.declareProtected(Permissions.AccessContentsInformation,
+                            'isSupportBaseDataConversion')
+  def isSupportBaseDataConversion(self):
+    """
+    """
+    return False
+
+ 
\ No newline at end of file

product/ERP5/mixin/html_convertable.py

+# -*- coding: utf-8 -*-
+##############################################################################
+#
+# Copyright (c) 2009 Nexedi SA and Contributors. All Rights Reserved.
+#                    Jean-Paul Smets-Solanes <jp@nexedi.com>
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# garantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+#
+##############################################################################
+
+import md5
+import string
+import xmlrpclib, base64, re, zipfile, cStringIO
+from xmlrpclib import Fault
+from xmlrpclib import Transport
+from xmlrpclib import SafeTransport
+from Acquisition import aq_base
+from AccessControl import ClassSecurityInfo
+from Products.ERP5Type import Permissions
+from Products.CMFCore.utils import getToolByName
+from Products.ERP5Type.Cache import DEFAULT_CACHE_SCOPE
+from Products.ERP5Type.Base import WorkflowMethod
+from zLOG import LOG
+from Products.ERP5Type.Cache import CachingMethod
+
+# Mixin import
+from Products.ERP5.mixin.convertable import ConvertableMixin
+from Products.ERP5.mixin.cached_convertable import CachedConvertableMixin
+
+
+
+class HTMLConvertableMixin(CachedConvertableMixin):
+  """
+  This class provides a generic implementation of IHTMLConvertable.
+
+  """
+
+  # Declarative security
+  security = ClassSecurityInfo()
+
+
+  # Declarative security
+  security = ClassSecurityInfo()
+  security.declareObjectProtected(Permissions.AccessContentsInformation)
+  
+  security.declarePrivate('_asHTML')
+  def _asHTML(self, **kw):
+    """
+      A private method which converts to HTML. This method
+      is the one to override in subclasses.
+    """
+    if not self.hasBaseData():
+      raise ConversionError('This document has not been processed yet.')
+    try:
+      # FIXME: no substitution may occur in this case.
+      mime, data = self.getConversion(format='base-html')
+      return data
+    except KeyError:
+      kw['format'] = 'html'
+      mime, html = self.convert(**kw)
+      return html
+
+  security.declareProtected(Permissions.View, 'asEntireHTML')
+  def asEntireHTML(self, **kw):
+    """
+      Returns a complete HTML representation of the document
+      (with body tags, etc.). Adds if necessary a base
+      tag so that the document can be displayed in an iframe
+      or standalone.
+
+      Actual conversion is delegated to _asHTML
+    """
+    html = self._asHTML(**kw)
+    if self.getUrlString():
+      # If a URL is defined, add the base tag
+      # if base is defined yet.
+      html = str(html)
+      if not html.find('<base') >= 0:
+        base = '<base href="%s">' % self.getContentBaseURL()
+        html = html.replace('<head>', '<head>%s' % base)
+      self.setConversion(html, mime='text/html', format='base-html')
+    return html
+
+  security.declareProtected(Permissions.View, 'asStrippedHTML')
+  def asStrippedHTML(self, **kw):
+    """
+      Returns a stripped HTML representation of the document
+      (without html and body tags, etc.) which can be used to inline
+      a preview of the document.
+    """
+    if not self.hasBaseData():
+      return ''
+    try:
+      # FIXME: no substitution may occur in this case.
+      mime, data = self.getConversion(format='stripped-html')
+      return data
+    except KeyError:
+      kw['format'] = 'html'
+      mime, html = self.convert(**kw)
+      return self._stripHTML(str(html))
+  
+  def _guessEncoding(self, string):
+    """
+      Try to guess the encoding for this string.
+      Returns None if no encoding can be guessed.
+    """
+    try:
+      import chardet
+    except ImportError:
+      return None
+    return chardet.detect(string).get('encoding', None)
+
+  def _stripHTML(self, html, charset=None):
+    """
+      A private method which can be reused by subclasses
+      to strip HTML content
+    """
+    body_list = re.findall(self.body_parser, str(html))
+    if len(body_list):
+      stripped_html = body_list[0]
+    else:
+      stripped_html = html
+    # find charset and convert to utf-8
+    charset_list = self.charset_parser.findall(str(html)) # XXX - Not efficient if this
+                                         # is datastream instance but hard to do better
+    if charset and not charset_list:
+      # Use optional parameter is we can not find encoding in HTML
+      charset_list = [charset]
+    if charset_list and charset_list[0] not in ('utf-8', 'UTF-8'):
+      try:
+        stripped_html = unicode(str(stripped_html),
+                                charset_list[0]).encode('utf-8')
+      except (UnicodeDecodeError, LookupError):
+        return str(stripped_html)
+    return stripped_html  
\ No newline at end of file

product/ERP5/mixin/metadata_discoverable.py

+# -*- coding: utf-8 -*-
+##############################################################################
+#
+# Copyright (c) 2009 Nexedi SA and Contributors. All Rights Reserved.
+#                    Jean-Paul Smets-Solanes <jp@nexedi.com>
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# garantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+#
+##############################################################################
+
+import md5
+import string
+import xmlrpclib, base64, re, zipfile, cStringIO
+from xmlrpclib import Fault
+from xmlrpclib import Transport
+from xmlrpclib import SafeTransport
+from Acquisition import aq_base
+from AccessControl import ClassSecurityInfo
+from Products.ERP5Type import Permissions
+from Products.CMFCore.utils import getToolByName
+from Products.ERP5Type.Cache import DEFAULT_CACHE_SCOPE
+from Products.ERP5Type.Base import WorkflowMethod
+from zLOG import LOG
+from Products.ERP5Type.Cache import CachingMethod
+
+# Mixin import
+from Products.ERP5.mixin.convertable import ConvertableMixin
+from Products.ERP5.mixin.html_convertable import HTMLConvertableMixin
+
+
+
+
+class MetadataDiscoverableMixin(HTMLConvertableMixin):
+  """
+  This class provides a generic implementation of IMetadataDiscoverable.
+
+  """
+
+  # Declarative security
+  security = ClassSecurityInfo()
+
+
+  # Declarative security
+  security = ClassSecurityInfo()
+  security.declareObjectProtected(Permissions.AccessContentsInformation)
+  
+
+
+  security.declareProtected(Permissions.AccessContentsInformation, 'getContentInformation')
+  def getContentInformation(self):
+    """
+    Returns the content information from the HTML conversion.
+    The default implementation tries to build a dictionnary
+    from the HTML conversion of the document and extract
+    the document title.
+    """
+    result = {}
+    html = self.asEntireHTML()
+    if not html: return result
+    title_list = re.findall(self.title_parser, str(html))
+    if title_list:
+      result['title'] = title_list[0]
+    return result
+
+  
\ No newline at end of file

product/ERP5/mixin/text_convertable.py

+# -*- coding: utf-8 -*-
+##############################################################################
+#
+# Copyright (c) 2009 Nexedi SA and Contributors. All Rights Reserved.
+#                    Jean-Paul Smets-Solanes <jp@nexedi.com>
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# garantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+#
+##############################################################################
+
+import md5
+import string
+import xmlrpclib, base64, re, zipfile, cStringIO
+from xmlrpclib import Fault
+from xmlrpclib import Transport
+from xmlrpclib import SafeTransport
+from Acquisition import aq_base
+from AccessControl import ClassSecurityInfo
+from Products.ERP5Type import Permissions
+from Products.CMFCore.utils import getToolByName
+from Products.ERP5Type.Cache import DEFAULT_CACHE_SCOPE
+from Products.ERP5Type.Base import WorkflowMethod
+from zLOG import LOG
+from Products.ERP5Type.Cache import CachingMethod
+
+# Mixin import
+from Products.ERP5.mixin.convertable import ConvertableMixin
+
+
+
+
+class TextConvertableMixin:
+  """
+  This class provides a generic implementation of ITextConvertable.
+
+    This class provides a generic API to store in the ZODB
+    various converted versions of a file or of a string.
+
+    Versions are stored in dictionaries; the class stores also
+    generation time of every format and its mime-type string.
+    Format can be a string or a tuple (e.g. format, resolution).
+  """
+
+  # Declarative security
+  security = ClassSecurityInfo()
+
+
+  # Declarative security
+  security = ClassSecurityInfo()
+  security.declareObjectProtected(Permissions.AccessContentsInformation)
+  
+
+  security.declareProtected(Permissions.View, 'asText')
+  def asText(self, **kw):
+    """
+      Text Convertable interface specification
+      Documents which implement the ITextConvertable interface
+      can be converted to plain text.
+      Converts the content of the document to a textual representation.
+    """
+    kw['format'] = 'txt'
+    mime, data = self.convert(**kw)
+    return str(data)
+
+  
+  security.declareProtected(Permissions.View, 'asSubjectText')
+  def asSubjectText(self, **kw):
+    """
+      Converts the subject of the document to a textual representation.
+    """
+    subject = self.getSubject()
+    if not subject:
+      # XXX not sure if this fallback is a good idea.
+      subject = self.getTitle()
+    if subject is None:
+      subject = ''
+    return str(subject)
\ No newline at end of file