+CAS_TICKET_EXPIRATION - minutes to tickets expiration. Default is 5 minutes.
+
+CAS_CUSTOM_ATTRIBUTES_CALLBACK - name of callback to provide dictionary with
+extended user attributes (may be used in CAS v.2 or above). Default is None.
+
+CAS_CUSTOM_ATTRIBUTES_FORMAT - name of custom attribute formatter callback will be
+used to format custom user attributes. This package provide module `attribute_formatters`
+with formatters for common used formats. Available formats styles are `RubyCAS`, `Jasig`
+and `Name-Value. Default is Jasig style. See module source code for more details.
+
+CAS_AUTO_REDIRECT_AFTER_LOGOUT - If False (default behavior, specified in CAS protocol)
+after successful logout notification page will be shown. If it's True, after successful logout will
+be auto redirect back to service without any notification.
+
+
+PROTOCOL DOCUMENTATION
+=====================
+
+* `CAS Protocol <http://www.jasig.org/cas/protocol>`
+* `CAS 1 Architecture <http://www.jasig.org/cas/cas1-architecture>`
+* `CAS 2 Architecture <http://www.jasig.org/cas/cas2-architecture>`
+* `Proxy Authentication <http://www.jasig.org/cas/proxy-authentication>`
+* `CAS – Central Authentication Service <http://www.jusfortechies.com/cas/overview.html>`
+* `Proxy CAS Walkthrough <https://wiki.jasig.org/display/CAS/Proxy+CAS+Walkthrough>`
+
+PROVIDED VIEWS
+=============
+
+login
+---------
+
+It has not required arguments.
+
+Optional arguments:
+
+* template_name - login form template name (default is 'cas/login.html')
+* success_redirect - redirect after successful login if service GET argument is not provided
+ (default is settings.LOGIN_REDIRECT_URL)
+* warn_template_name - warning page template name to allow login user to service if he
+ already authenticated in SSO (default is 'cas/warn.html')
+
+If request.GET has 'warn' argument and user has already authenticated in SSO it shows
+warning message instead of generate Service Ticket and redirect.
+
+logout
+-----------
+
+This destroys a client's single sign-on CAS session. The ticket-granting cookie is destroyed,
+and subsequent requests to login view will not obtain service tickets until the user again
+presents primary credentials (and thereby establishes a new single sign-on session).
+
+It has not required arguments.
+
+Optional arguments:
+
+* template_name - template name for page with successful logout message (default is 'cas/logout.html')
+
+validate
+-------------
+
+It checks the validity of a service ticket. It is part of the CAS 1.0 protocol and thus does
+not handle proxy authentication.
+
+It has not arguments.
+
+service_validate
+-------------------------
+
+It checks the validity of a service ticket and returns an XML-fragment response via CAS 2.0 protocol.
+Work with proxy is not supported yet.
+
+It has not arguments.
+
+
+CUSTOM USER ATTRIBUTES FORMAT
+===========================
+
+Custom attribute format style may be changed in project settings with
+CAS_CUSTOM_ATTRIBUTES_FORMAT constant. You can provide your own formatter callback
+or specify existing in this package in `attribute_formatters` module.
+
+Attribute formatter callback takes two arguments:
+
+* `auth_success` - `cas:authenticationSuccess` node. It is `lxml.etree.SubElement`instance;
+* `attrs` - dictionary with user attributes received from callback specified in
+ CAS_CUSTOM_ATTRIBUTES_CALLBACK in project settings.
+
+Example of generated XML below::
+
+ <cas:serviceResponse xmlns:cas='http://www.yale.edu/tp/cas'>
+ <cas:authenticationSuccess>
+ <cas:user>jsmith</cas:user>
+
+ <!-- extended user attributes wiil be here -->
+
+ <cas:proxyGrantingTicket>PGTIOU-84678-8a9d2sfa23casd</cas:proxyGrantingTicket>
+ </cas:authenticationSuccess>
+ </cas:serviceResponse>
+
+
+* Name-Value style (provided in `cas_provider.attribute_formatters.name_value`)::
+
+ <cas:attribute name='attraStyle' value='Name-Value' />
+ <cas:attribute name='surname' value='Smith' />
+ <cas:attribute name='givenName' value='John' />
+ <cas:attribute name='memberOf' value='CN=Staff,OU=Groups,DC=example,DC=edu' />
+ <cas:attribute name='memberOf' value='CN=Spanish Department,OU=Departments,OU=Groups,DC=example,DC=edu' />
+
+
+* Jasig Style attributes (provided in `cas_provider.attribute_formatters.jasig`)::
+
+ <cas:attributes>
+ <cas:attraStyle>Jasig</cas:attraStyle>
+ <cas:surname>Smith</cas:surname>
+ <cas:givenName>John</cas:givenName>
+ <cas:memberOf>CN=Staff,OU=Groups,DC=example,DC=edu</cas:memberOf>
+ <cas:memberOf>CN=Spanish Department,OU=Departments,OU=Groups,DC=example,DC=edu</cas:memberOf>
+ </cas:attributes>
+
+
+* RubyCAS style (provided in `cas_provider.attribute_formatters.ruby_cas`)::
+
+ <cas:attraStyle>RubyCAS</cas:attraStyle>
+ <cas:surname>Smith</cas:surname>
+ <cas:givenName>John</cas:givenName>
+ <cas:memberOf>CN=Staff,OU=Groups,DC=example,DC=edu</cas:memberOf>
+ <cas:memberOf>CN=Spanish Department,OU=Departments,OU=Groups,DC=example,DC=edu</cas:memberOf>