Connecting web Applications with Desktop, confoo 2011

Connecting web and desktop: WebDAV ConFoo 2011 Tobias Schlitt <toby@qafoo.com> March 10, 2011

Connecting web and desktop: WebDAV 2 / 49 Outline Introduction HTTP & WebDAV Development challenges Zeta Webdav component

Connecting web and desktop: WebDAV 3 / 49 About me Degree in computer sience More than 10 years of professional PHP Open source enthusiast Apache Zeta Components Arbit PHPUnit ...

Connecting web and desktop: WebDAV 3 / 49 About me Degree in computer sience Co-Founder of More than 10 years of Qafoo GmbH professional PHP http://qafoo.com Open source enthusiast Apache Zeta Components Qafoo passion for software quality Arbit PHPUnit ...

Connecting web and desktop: WebDAV 3 / 49 About me Degree in computer sience Co-Founder of More than 10 years of Qafoo GmbH professional PHP http://qafoo.com Open source enthusiast Apache Zeta Components Qafoo passion for software quality Arbit We help people to produce PHPUnit ... high quality PHP code.

Connecting web and desktop: WebDAV 5 / 49 The concept GET /some/resource

Connecting web and desktop: WebDAV 5 / 49 The concept POST /some/resource ???

Connecting web and desktop: WebDAV 5 / 49 The concept PUT /some/resource ???

Connecting web and desktop: WebDAV 5 / 49 The concept Please ﬁle that document under /some/resource Done.

Connecting web and desktop: WebDAV 5 / 49 The concept Please create a new collection of documents under /some/more Done.

Connecting web and desktop: WebDAV 6 / 49 HTTP Network protocol driving the web Current version: 1.1 RFC 2616 (June 1999) http://tools.ietf.org/html/rfc2616 Inventor: Sir Tim Berners-Lee Client / server based Stateless communication Deﬁnes Request / response Headers / body Formats / actions

Connecting web and desktop: WebDAV 7 / 49 WebDAV HTTP Extensions for Distributed Authoring RFC 2518 (February 1999) http://tools.ietf.org/html/rfc2518 HTTP Extensions for Web Distributed Authoring and Versioning RFC 4918 (June 2007) http://tools.ietf.org/html/rfc4918 IETF Standard Extension to HTTP Allows distributed editing

Connecting web and desktop: WebDAV 7 / 49 WebDAV HTTP Extensions for Distributed Authoring RFC 2518 (February 1999) http://tools.ietf.org/html/rfc2518 HTTP Extensions for Web Distributed Authoring and Versioning RFC 4918 (June 2007) http://tools.ietf.org/html/rfc4918 IETF Standard Extension to HTTP Allows distributed editing WebDAV allows your users to edit web content easily.

Connecting web and desktop: WebDAV 8 / 49 Request methods HTTP WebDAV GET MKCOL POST COPY HEAD MOVE PUT PROPFIND DELETE PROPPATCH OPTIONS LOCK TRACE UNLOCK CONNECT

Connecting web and desktop: WebDAV 8 / 49 Request methods HTTP WebDAV GET MKCOL POST COPY HEAD MOVE PUT PROPFIND DELETE PROPPATCH OPTIONS LOCK TRACE UNLOCK CONNECT Signiﬁcant for WebDAV

Connecting web and desktop: WebDAV 9 / 49 Request headers HTTP WebDAV Accept[-*] Depth Authorization Destination If-[None-]Match If If-[Un]Modiﬁed-Since Overwrite User-Agent Timeout ...

Connecting web and desktop: WebDAV 9 / 49 Request headers HTTP WebDAV Accept[-*] Depth Authorization Destination If-[None-]Match If If-[Un]Modiﬁed-Since Overwrite User-Agent Timeout ... Signiﬁcant for WebDAV

Connecting web and desktop: WebDAV 10 / 49 Response headers HTTP WebDAV Accept-Ranges DAV Content-Length Lock-Token Content-Type Timeout ETag Location Retry-After Server WWW-Authenticate ...

Connecting web and desktop: WebDAV 10 / 49 Response headers HTTP WebDAV Accept-Ranges DAV Content-Length Lock-Token Content-Type Timeout ETag Location Retry-After Server WWW-Authenticate ... Signiﬁcant for WebDAV

Connecting web and desktop: WebDAV 11 / 49 Request / response bodies HTTP Request body mostly not signiﬁcant Only PUT method needs body (to be stored) Response body usually content to deliver (unspeciﬁed) Error responses may contain arbitrary content

Connecting web and desktop: WebDAV 11 / 49 Request / response bodies WebDAV Bodies are signiﬁcant Many methods require XML bodies Request Response PROPFIND PROPFIND PROPPATCH PROPPATCH COPY (optional) LOCK MOVE (optional) Potentially others LOCK (multi-status)

Connecting web and desktop: WebDAV 12 / 49 Properties Concept introduced by WebDAV Store meta information about content Usually not directly visible to the user Live properties Dead properties creationdate Arbitrary data displayname Custom namespace get* XML favored lockdiscovery ...

Connecting web and desktop: WebDAV 14 / 49 Development challenges Server development in general WebDAV RFCs are a BBOM Unstructured Ambiguous Design fails Misbehaving clients Ignore the speciﬁcation Diﬀerent interpretations of RFCs Proprietary BS Exchangeable back ends

Connecting web and desktop: WebDAV 15 / 49 Outline Development challenges RFC problems Client problems Back end ﬂexibility

Connecting web and desktop: WebDAV 16 / 49 COPY / MOVE methods Errors on COPY “[...] if an error occurs while copying an internal collection, the server MUST NOT copy any resources identiﬁed by members of this collection (i.e., the server must skip this subtree) [...]” [?] MOVE “[...] is the logical equivalent of a copy (COPY), followed by consistency maintenance processing, followed by a delete of the source,[...]” [?] MOVE errors “[...] after detecting the error, the move operation SHOULD try to ﬁnish as much of the original move as possible [...]” [?]

Connecting web and desktop: WebDAV 17 / 49 The If header Makes operations conditional. Apply operation only if all conditions are met no condition is met 1 No−tag − l i s t = L i s t 2 Tagged− l i s t = R e s o u r c e 1∗ L i s t 3 Resource = Coded−URL 4 List = ”(” 5 1 ∗ ( [ ” Not ” ] ( S t a t e −t o k e n | ” [ ” e n t i t y −t a g ” ] ” ) ) 6 ”)” 7 S t a t e −t o k e n = Coded−URL 8 Coded−URL = ”<” a b s o l u t e U R I ”>”

Connecting web and desktop: WebDAV 18 / 49 The If header Can contain lock tokens entity tags 1 I f : (< l o c k t o k e n : a−w r i t e −l o c k −t o k e n > 2 [ ” I am an ETag” ] ) ( [ ” I am a n o t h e r ETag” ] )

Connecting web and desktop: WebDAV 19 / 49 The If header Conditions can apply to single resources sets of resources all aﬀected resources 1 <h t t p : // e x a m p l e . com/ r e s o u r c e 1 > 2 (< l o c k t o k e n : a−w r i t e −l o c k −t o k e n > [W/ ”A weak ETag” ] ) 3 ( Not [ ” s t r o n g ETag” ] ) Required own parser implementation Parser is about 150 LOC

Connecting web and desktop: WebDAV 20 / 49 Locking 2 different types of locks Exclusive Shared Lock conditions must be validated before anything else Timeout refresh on every lock use (successful or not) (Fixed in RCF 4918) Not specified how to associate principles with lock tokens Lock-Null-Resources (Partly fixed in RFC 4918) Do not behave like real resources Must vanish when the lock is released A collection can be created on them

Connecting web and desktop: WebDAV 22 / 49 Konqueror / Nautilus Konqueror (KDE) Does not decode URLs properly Requires Apache like error messages for 404 Nautilus (Gnome) Cannot cope with charset="..." info in MIME types

Connecting web and desktop: WebDAV 23 / 49 Windows / InternetExplorer At least 3 diﬀerent WebDAV user agents in Windows Loaded depending on how you initialize connection Transparently switched occasionally Requires custom header MS-Author-Via on every response Requires custom namespaces set on live properties Requires special namespace shortcut to be used (sic!) Requires diﬀerent shortcuts for DAV: namespace

Connecting web and desktop: WebDAV 24 / 49 Windows / InternetExplorer II Cannot cope with non-signiﬁcant white spaces in XML bodies Requires newline at the end of every XML body Occasionally sends invalid PROPFIND requests

Connecting web and desktop: WebDAV 26 / 49 Back end ﬂexibility Exchangeable back end File system Memory (testing) SQL Database? Subversion? Independent of client issues Protocol enhancements back end independent Easy implementation

Connecting web and desktop: WebDAV 28 / 49 Outline Zeta Webdav component Background Usage Customization End note

Connecting web and desktop: WebDAV 29 / 49 eZ Components

Connecting web and desktop: WebDAV 29 / 49 Apache Zeta Components apache Zeta Components

Connecting web and desktop: WebDAV 30 / 49 History: eZ Components Developed since 2004 by eZ Systems AS Makers of enterprise OSS CMS eZ Publish http://ez.no Initial goal Refactor and cleanup core libs of eZ Publish Pull out standalone, general purpose library Objectives High quality code Well thought out API Backwards compatibility Extensive documentation

Connecting web and desktop: WebDAV 31 / 49 History: The break March 2010 All eZ Components developers left eZ Systems Still, we wanted to . . . put voluntary eﬀorts into the project push it further ensure it is not broken Discussion with eZ Systems Spin oﬀ the project to become independent Look for or create a foundation Result: Propose code to Apache Software Foundation

Connecting web and desktop: WebDAV 32 / 49 Apache Software Foundation http://apache.org Well knwon OSS foundation Home of OSS projects like Apache HTTP server Subversion CouchDB http://zeta-components.org

Connecting web and desktop: WebDAV 33 / 49 The Webdav component General purpose WebDAV server Easy integration and customization Work around client issues

Connecting web and desktop: WebDAV 34 / 49 Zeta Webdav architecture Transport layer Plugins Microsoft Nautilus RFC conform compatible Lock plugin compatible transport transport transport Your custom plugin Server layer Your authentication / Plugin API authorization Back end layer Simple backend (base class) File system eZ Publish Your custom back end back end back end

Connecting web and desktop: WebDAV 36 / 49 Setup a simple WebDAV server 1 $ s e r v e r = ezcWebdavServer : : g e t I n s t a n c e ( ) ; 2 $ b a c k e n d = new e z c W e b d a v F i l e B a c k e n d ( 3 dirname ( FILE ) . ’ / backend ’ 4 ); 5 6 $ s e r v e r − andle ( $backend ) ; >h

Connecting web and desktop: WebDAV 37 / 49 WebDAV server with locking 1 require once ’ c u s t o m l o c k a u t h . php ’ ; 2 3 $ s e r v e r = ezcWebdavServer : : g e t I n s t a n c e ( ) ; 4 5 $ s e r v e r − u t h = new myCustomLockAuth ( >a 6 // Some c o n f i g u r a t i o n d i r e c t o r y h e r e 7 dirname ( FILE ) . ’ / t o k e n s . php ’ 8 ); 910 $server− luginRegistry− e g i s t e r P l u g i n ( >p >r11 new e z c W e b d a v L o c k P l u g i n C o n f i g u r a t i o n ( )12 );1314 $ b a c k e n d = new e z c W e b d a v F i l e B a c k e n d (15 // Your WebDAV d i r e c t o r y h e r e16 dirname ( FILE ) . ’ / backend ’17 );1819 $ s e r v e r − andle ( $backend ) ; >h

Connecting web and desktop: WebDAV 38 / 49 Authentication 1 i n t e r f a c e ezcWebdavAnonymousAuthenticator 2 { 3 p u b l i c f u n c t i o n a u t h e n t i c a t e A n o n y m o u s ( ezcWebdavAnonymousAuth $ d a t a ) ; 4 } 1 i n t e r f a c e ezcWebdavBasicAuthenticator e x t e n d s ezcWebdavAnonymousAuthenticator 2 { 3 p u b l i c f u n c t i o n a u t h e n t i c a t e B a s i c ( ezcWebdavBasicAuth $data ) ; 4 } 1 i n t e r f a c e ezcWebdavDigestAuthenticator extends ezcWebdavBasicAuthenticator 2 { 3 p u b l i c f u n c t i o n a u t h e n t i c a t e D i g e s t ( ezcWebdavDigestAuth $data ) ; 4 }

Connecting web and desktop: WebDAV 39 / 49 Authorization 1 i n t e r f a c e ezcWebdavAuthorizer 2 { 3 c o n s t ACCESS READ = 1 ; 4 c o n s t ACCESS WRITE = 2 ; 5 6 p u b l i c f u n c t i o n a u t h o r i z e ( $ u s e r , $path , $ a c c e s s = s e l f : : ACCESS READ ) ; 7 } 1 i n t e r f a c e ezcWebdavLockAuthorizer extends ezcWebdavAuthorizer 2 { 3 p u b l i c f u n c t i o n assignLock ( $user , $lockToken ) ; 4 5 p u b l i c f u n c t i o n ownsLock ( $ u s e r , $ l o c k T o k e n ) ; 6 7 p u b l i c f u n c t i o n r e l e a s e L o c k ( $user , $lockToken ) ; 8 }

Connecting web and desktop: WebDAV 41 / 49 Path handling 1 $ s e r v e r = ezcWebdavServer : : g e t I n s t a n c e ( ) ; 2 3 $ p a t h F a c t o r y = new e z c W e b d a v B a s i c P a t h F a c t o r y ( 4 ’ h t t p : / / e x a m p l e . com/ webdav / i n d e x . php ’ 5 ); 6 7 foreach ( $server− o n f i g u r a t i o n s as $conf ) >c 8 { 9 $ c o n f− a t h F a c t o r y = $ p a t h F a c t o r y ; >p10 }1112 $ b a c k e n d = new e z c W e b d a v F i l e B a c k e n d (13 dirname ( FILE ) . ’ / backend ’14 );1516 $ s e r v e r − andle ( $backend ) ; >h

Connecting web and desktop: WebDAV 42 / 49 The back end ezcWebdavFileBackend ezcWebdavMemoryBackend Write your own ezcWebdavSimpleBackend ezcWebdavBackend ezcWebdavBackendPut ezcWebdavBackendChange ezcWebdavBackendMakeCollection ezcWebdavLockBackend

Connecting web and desktop: WebDAV 43 / 49 ezcWebdavSimpleBackend Proper method handling Authorization Handling of If[-*] headers about 1600 LOC No deeper knowledge on WebDAV required

Connecting web and desktop: WebDAV 44 / 49 New clients Adjust transport layer Needs some patience Use Wireshark! Extend one or more of ezcWebdavTransport ezcWebdavHeaderHandler ezcWebdavPropertyHandler

Connecting web and desktop: WebDAV 44 / 49 New clients Adjust transport layer Needs some patience Use Wireshark! Extend one or more of ezcWebdavTransport ezcWebdavHeaderHandler ezcWebdavPropertyHandler 1 $ n e w C l i e n t C o n f = new e z c W e b d a v S e r v e r C o n f i g u r a t i o n ( 2 ’ (My. ∗ Webdav s+C l i e n g t ) i ’ , 3 ’ myCustomTransportTransport ’ 4 // . . . 5 ); 6 7 $server− o n f i g u r a t i o n s − n s e r t B e f o r e ( $newClientConf , 0 ) ; >c >i

Connecting web and desktop: WebDAV 45 / 49 Plugins Hook into requests / responses Handle unknown requests Issue unknown responses Send requests to the back end

Connecting web and desktop: WebDAV 47 / 49 Join the team! Come and contribute! Highly technical discussions Open minded people Apache Software Foundation http://zeta-components.org

Connecting web and desktop: WebDAV 48 / 49 Q/A Are there any questions left?

Connecting web and desktop: WebDAV 49 / 49 Thanks for listening Please rate this talk at http://joind.in/2808 and / or give me some feedback right now!

Connecting web and desktop: WebDAV 49 / 49 Thanks for listening Please rate this talk at http://joind.in/2808 and / or give me some feedback right now! This is very important for . . . Speakers Organizers You!

Connecting web and desktop: WebDAV 49 / 49 Thanks for listening Please rate this talk at http://joind.in/2808 and / or give me some feedback right now! Stay in touch Tobias Schlitt toby@qafoo.com @tobySen / @qafoo Rent a PHP quality expert: http://qafoo.com

Connecting web Applications with Desktop, confoo 2011

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