Web-based file systems and WebDAV gateway services to CERN DFS file system Alexandre Lossent, Alberto Pace

Agenda  Cross platform File sharing issues  (from 2 years ago)  What is WebDAV ?  WebDAV software overview  Servers  Clients  WebDAV at CERN

Agenda  Cross platform File sharing issues  (from 2 years ago)  What is WebDAV ?  WebDAV software overview  Servers  Clients  WebDAV at CERN

Introductory reminder: a slide from a presentation made 2 years ago (June 2001)

Present values of the AFS file sharing services  Native to all UNIX platforms  Fully integrated in the environment, in the shell  Seen by all applications as a “native” file system  It is global on the internet  Files natively shareable across institutes  Good technical implementation (cache) minimizes internet traffic June 2001

AFS is a success in HEP  Lot of information is currently shared across HEP sites using AFS  An AFS file path, identifies universally a file or a directory content  AFS has become “the standard” for file and data sharing in the UNIX/HEP world  HEP users are used to share data across the internet using AFS June 2001

What we would like for the future  Native access, including …  Shell access, Access Control, Source control, versioning, offline files  Global internet sharing  Consolidated Standard  Multiple vendors, strong support, interoperability, outsourceable …  Cross platform  Windows, Linux, Mac OS X  Free  At least the client software  Better if source code is available An AFS/DFS-like solution ( ) A web based solution ( ) Difficult to have both … June 2001

A good news  A web based solution does no longer imply non-native  If the web based file system is implemented at the OS level, applications can access it natively ! Back to October 2003

The “Web” is part of the solution  Standard extensions to the HTTP protocol allow managing files on web servers as if these would be part of the local file system  HTTP Extensions for Distributed Authoring (WebDAV IETF RFC 2518) have been widely adopted on all major OS  Several commercial and public-domain implementations exists

Agenda  Cross platform File sharing issues  (from 2 years ago)  What is WebDAV ?  WebDAV software overview  Servers  Clients  WebDAV at CERN

WebDAV  Web Distributed Authoring and Versioning  IETF RFC 2518 (February 1999)   An extension to the HTTP protocol  New verbs (PROPFIND, MKCOL, LOCK...), headers and status codes  Uses XML to format information  Initially designed as a way to author web sites  Redundant with FPSE in the Windows world  Versioning is limited to file locking (check in/out)  Can be used as a low-end network filesystem  WebDAV Home page   See it also for related open-source projects

WebDAV today  File access:  Create / delete files and folders  Read / write files  Copy / Move / Delete / rename files and folders  Document locking  prevent the overwrite problem, where two or more collaborators write to the same resource without first merging changes  Allow implementation of offline folders  Properties  XML properties provide storage for arbitrary metadata

On Windows Nautilus- Gnome On Linux

Windows Console SSH session On Linux

WebDAV tomorrow ?  Access control  Set / View / Modify Access Control lists using http  Versioning and Configuration Management  The V in WebDAV means “Versioning”  Document check-out, check-in  Retrieval of the history list  Offline files and folders  Other advanced features  Symbolic links  Ordered collections  Aggregated operations

For the “advanced features” …  The standard is being discussed since few years  Without real consensus on a common standard  Proprietary implementations already available  Example: Microsoft Sharepoint services

Is this a solution ?  WebDAV is currently implemented at the “application” level  This means that applications that are WebDAV enabled can see files on web servers, otherwise not This is not a solution. The WebDAV client must be done at the operating system level as a “file redirector”. This means that any application is able access WebDAV servers. This feature is already available on MacOS X, Windows XP and partially Windows There are open source implementations on Linux being worked at. (see news)

Agenda  Cross platform File sharing issues  (from 2 years ago)  What is WebDAV ?  WebDAV software overview  Servers  Clients  WebDAV at CERN

WebDAV servers  Supported by all common web servers  Apache module mod_dav  WebDAV package in PHP PEAR  Built-in support in IIS 5 and 6  Need to activate appropriate HTTP verbs: PUT (write setting), PROPFIND (directory browsing setting)  Permissions are managed by NTFS ACLs  Microsoft adds a header to the WebDAV protocol for a HTTP GET to return a script’s output or its source (source access setting)

WebDAV clients  Clients exist on all major platforms  See again  3 flavors of clients with different usage:  Basic WebDAV clients or libraries  GUI or command-line to browse/download/upload files (but not edit them in-place); similar to FTP  E.g. IE5+, Nautilus, Perl / Java libraries...  WebDAV-enabled applications  Can access and edit files over WebDAV  E.g. Adobe, Macromedia, MS Office...  Operating system drivers  Allow to mount a WebDAV resource in a file system  Enables in-place edition for all applications  E.g. WinXP’s mini-redirector, Mac OS X built-in client, Linux davfs...

WebDAV clients: Windows (1)  Office Web Folders (msdaipp.dll)  Included in Office 2000/XP and Windows 2000 but NOT in XP/2003 (unless Office is installed)  Allows in-place edition of Office documents on web servers  Allows Internet Explorer to browse WebDAV and FPSE- enabled web sites (like FTP sites)  Supports HTTPS and all authentication methods  Implemented as an OLE DB data provider

WebDAV clients: Windows (2)  WinXP/2003 WebClient (WebDAV redirector)  You’ll find it in “Administrative Tools” – “Services”  A network file system driver  WebDAV folders transparently mounted as file system and made available to all applications using UNC paths !  Folders are viewed in Windows Explorer like usual folders, with same functionality  Limited to HTTP on port 80 and basic or Kerberos authentication (!)  We are in discussion with MS to void the http limitation

WebDAV clients: Windows (3) MS OfficeInternet ExplorerOther applications... Office Web Folders / MSDAIPP Ships with MS Office and W2k WebClient / WebDAV redirector Ships with Windows XP/2003 FPSE serverWebDAV server Windows XP/2003 only

WebDAV clients: Windows (4) Windows 2000 Windows XP/2003 Windows XP/2003 with Office HTTPWebFoldersRedirector HTTPS or custom port WebFoldersN/AWebFolders WebDAV client used by Internet Explorer when a WebDAV location is opened

WebDAV clients: Macintosh  Built-in filesystem driver in OS X  Similar to XP’s WebDAV redirector  Supports only HTTP and basic authentication (!)  Works ok will all Mac Applications tested so far, including Office  Open-source Goliath project (Mac OS > 8.6)  Supports HTTPS  GUI interface to check in/out files  Files are edited in a local folder  Then use the GUI to check out modified version  Plus an wide number of commercial applications with built-in WebDAV support (as for Windows)  Example: Adobe, Macromedia, …

WebDAV clients: Linux  Command-line and GUI utilities (FTP-like)  E.g. Cadaver is available in standard CERN distributions  Filesystem driver  Davfs (again, limited to HTTP and basic authentication) (!)  But source code available and HTTPS prototype exists  Many open-source libraries  KDE, PerlDAV, Jakarta Slide Project...  Plus all commercial applications with built-in WebDAV support (as for Macintosh and Windows)  Generally, not well integrated yet  The Davfs filesystem being the exception  This might change with KDE/Gnome projects

WebDAV on Windows

WebDAV on Macintosh (1)

WebDAV on Macintosh (2)

WebDAV on Linux

Agenda  Cross platform File sharing issues  (from 2 years ago)  What is WebDAV ?  WebDAV software overview  Servers  Clients  WebDAV at CERN

The WebDAV–DFS gateway  Built using IIS 6 / Windows 2003  Basically a WebDAV-enabled virtual folder that points to \\cern.ch\dfs\\cern.ch\dfs  All script mappings are disabled  no need for the Microsoft-specific SourceAccess flag  Basic authentication  The only method widely supported  http[s]://dfs.cern.ch/dfs http[s]://dfs.cern.ch/dfs

The WebDAV–DFS gateway (2)  Current issues and limitations:  Files Locked in WebDAV are also locked in DFS  If the client does not explicitly unlock them, restart IIS to free the lock (!!)  Some clients abusively create additional files/folders  Mac OS X  Permissions cannot be managed – not an issue for CERN – see below  Internet access limited to https  A web interface has been added   Enables access to the DFS from any browser  Complete file management capabilities  including permission management  Aggregate operations

Future: web site editing  Replace insecure FTP by a WebDAV service for web site editing  May Run on different port so that the security of the main site is not compromised  Remember the “source access setting” ?  Configuration similar to the gateway  Authentication mandatory  No script mappings  Or … cross mount local Web storage into DFS

WebDAV access to Exchange  WebDAV is “the” protocol for exchange / mail workflow automation  Many native Exchange clients use http instead of MAPI  Ximian connector on Linux  Outlook 2003 uses http instead of MAPI  After the “Blaster Worm” MAPI on the internet is dead (port 135 closed everywhere)  At CERN, prototype project to integrate Official Leave requests automatically in the Exchange calendar using WebDAV

WebDAV access to Exchange

Summary  Use of WebDAV as interoperable network filesystem possible today  Can be applied to collaborative tools as well (Exchange)  Takes advantage of HTTP and XML ubiquity  Excellent level of interoperability for file access  Really reachable from any device / anywhere  Very simple to implement  But...  Still few implementation glitches  https support is still limited  Not a high-performance file system  Not a replacement for native file system (eg NTFS)  Permission management still require custom implementations