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revision 1.202 by benja, Mon Nov 10 09:45:08 2003 UTC revision 1.203 by benja, Mon Nov 10 09:49:05 2003 UTC
# Line 114  from any host with a copy. This would sa Line 114  from any host with a copy. This would sa
114  and increase availability; pages would stay online as long as  and increase availability; pages would stay online as long as
115  any user keeps a copy of them on their local harddisk.  any user keeps a copy of them on their local harddisk.
116    
 .. XXX Mention "Name-based not possible as a suitable system  
    for names doesn't exist?"  
   
117  Such permanence is an important concern, as seen by the following example.  Such permanence is an important concern, as seen by the following example.
118  In 1997, NASA launched the Cassini-Huygens spacecraft  In 1997, NASA launched the Cassini-Huygens spacecraft
119  on a mission to Saturn. Before the launch, the mission  on a mission to Saturn. Before the launch, the mission
# Line 160  Off-line capability Line 157  Off-line capability
157         a change in the user interface or functionality,         a change in the user interface or functionality,
158         and to use a neighbouring computer's cache         and to use a neighbouring computer's cache
159         if the LAN is disconnected from the internet         if the LAN is disconnected from the internet
160    
161  Heterogeneity  Heterogeneity
162         The possibility to         The possibility to
163         use different P2P networks interchangeably, even         use different P2P networks interchangeably, even
# Line 169  Heterogeneity Line 167  Heterogeneity
167         exploits of single network; b) one size doesn't fit all         exploits of single network; b) one size doesn't fit all
168         (e.g. anonymity, efficiency); c) more people can use this         (e.g. anonymity, efficiency); c) more people can use this
169         (network effect)         (network effect)
170    
171    ..  XXX something that requires keeping info in one place
172        in one network will never be agreeable upon between
173        all networks
174    
175  Distributed archivability  Distributed archivability
176         The ability to         The ability to
177         keep a version originally published by         keep a version originally published by
# Line 177  Distributed archivability Line 180  Distributed archivability
180         (so that when the original publisher loses interest,         (so that when the original publisher loses interest,
181         a page does not fall off the Web).         a page does not fall off the Web).
182    
 .. To keep a version  
    of a page online, it does not suffice for one user  
    to download and store a copy; when the publisher  
    loses interest, the page disappears (except in the case  
    of Freenet, where pages disappear when they have not been  
    requested for a period of time).  
   
   
 ..  In conclusion, in a filesharing system, a file remains accessible  
     as long as there is a copy on any of the participating hosts;  
     none of the above versioning systems have this property. XXX not true  
   
     Thus, in these systems, when the original publisher loses interest  
     and stops publishing a page, it disappears, even if  
     someone else has kept a copy.  
   
183  In a P2P Web, pages could be  In a P2P Web, pages could be
184  linked using  permanent URIs  linked using  permanent URIs
185  based on the files' cryptographic  based on the files' cryptographic
# Line 211  systems that is vital for the Web to flo Line 198  systems that is vital for the Web to flo
198     infeasible to update all pages linking to it, and thus     infeasible to update all pages linking to it, and thus
199     all pages linking to *them*, and thus...     all pages linking to *them*, and thus...
200    
 ..  There are some non-filesharing P2P systems  
     that do offer an update mechanism. However, none of these  
     provides all the above benefits of a filesharing system:  
   
   
 .. <<<We don't propose that every byte of information ever published  
    on the Web has to be kept around forever. However,  
    we do believe that as long as someone does keep a copy,  
    data should remain accessible, like in a filesharing system,  
    and links should continue to work.>>>  
   
 .. <<<Other projects exploit some of the advantages of hash-based  
    (storage systems: CFS, PAST; web caching: Squirrel),  
    but don't address the Web.>>>  
   
 .. Possibility of desktop integration in ways that the location-dependent  
    Web cannot archieve, through the novel combination of  
    network transparency and location independence (ref ourselves).  
   
201  The main contribution of this paper is the use of *pointer records*,  The main contribution of this paper is the use of *pointer records*,
202  a versioning mechanism which is similar to OceanStore's heartbeats,  a versioning mechanism which is similar to OceanStore's heartbeats,
203  but allows the clients to download and store the pointer records  but allows the clients to download and store the pointer records
# Line 238  Instead of having a primary replica, we Line 206  Instead of having a primary replica, we
206  the whole P2P network for pointer records  the whole P2P network for pointer records
207  related to a document.  related to a document.
208    
 ..  XXX something that requires keeping info in one place  
     in one network will never be agreeable upon between  
     all networks  
   
209  An additional contribution is the Storm data model,  An additional contribution is the Storm data model,
210  an API formalizing the notion of searching for data  an API formalizing the notion of searching for data
211  by hash and content. The API is used by applications  by hash and content. The API is used by applications
# Line 364  will succeed remains to be seen. Line 328  will succeed remains to be seen.
328     semantics; for example, the NFS client for OceanStore only requests     semantics; for example, the NFS client for OceanStore only requests
329     new heartbeats less than 30 seconds old.     new heartbeats less than 30 seconds old.
330    
 ..  is unique among the versioned P2P systems  
     in that it  
331    
332  Pointer records  Pointer records
333  ===============  ===============
# Line 441  could be originally edited in OceanStore Line 403  could be originally edited in OceanStore
403  in Gnutella or a DHT-based system, using an anonymized system  in Gnutella or a DHT-based system, using an anonymized system
404  like Achord [hazel02achord]_ if it contains controversial content.  like Achord [hazel02achord]_ if it contains controversial content.
405    
 ..  - Carries over the four benefits from hash-based addressing:  
   
       - Version references movable between servers  
       - Past versions accessible as long as anyone keeps a copy  
       - Load balancing (download the pointer record from whoever has it)  
       - Can use one addressing scheme for *updateable* information,  
         searching different networks for versions  
   
406    
407  The Storm data model  The Storm data model
408  ====================  ====================
409    
 ..  XXX focus on the formalization of blocks and our  
     generalization of reverse indexing  
   
410  In this section, we introduce the Storm [#]_ data model,  In this section, we introduce the Storm [#]_ data model,
411  an API for storing and retrieving information using  an API for storing and retrieving information using
412  hash-based addressing. Storm provides a simple but powerful  hash-based addressing. Storm provides a simple but powerful
# Line 464  of P2P networks. The intent Line 415  of P2P networks. The intent
415  of this API is to decouple the application and network layers  of this API is to decouple the application and network layers
416  so that both can evolve independently.  so that both can evolve independently.
417    
 ..  The Storm API can be used  
     by P2P Web applications, which then do not have to deal  
     with each P2P network implementation independently.  
   
418  The Storm abstraction does not provide any new functionality;  The Storm abstraction does not provide any new functionality;
419  it merely provides a common API for the hash-based addressing  it merely provides a common API for the hash-based addressing
420  and content-based search present in many existing P2P systems.  and content-based search present in many existing P2P systems.
# Line 501  Reverse indices Line 448  Reverse indices
448      The server would publish the resulting mappings      The server would publish the resulting mappings
449      from words to block ids on the P2P network.      from words to block ids on the P2P network.
450    
 .. XXX kept out because of space constraints:  
   
    An index can also return additional information  
    to be placed in the hashtable along with the  
    block id. In the example, this could be the complete  
    metadata of the song, so that a client does not need  
    to download the complete audio file before being able  
    to show its artist, title etc. to its user.  
   
451  The pointer functionality is trivial to implement  The pointer functionality is trivial to implement
452  *on top of* this basic model. A pointer record  *on top of* this basic model. A pointer record
453  is simply a block with a special MIME type. A pointer record index  is simply a block with a special MIME type. A pointer record index
# Line 533  and Web namespaces can be unified; a doc Line 471  and Web namespaces can be unified; a doc
471  its address when published on the network, or when  its address when published on the network, or when
472  downloaded to the local harddisk [fallenstein03storm]_.  downloaded to the local harddisk [fallenstein03storm]_.
473    
 .. - can be made to work with peers that join and leave small  
      ad hoc networks often (and the global "net" less often)  
    -> XXX what does this mean?  
   
474    
475  Applications  Applications
476  ============  ============
# Line 552  is the implementation of a file-shared w Line 486  is the implementation of a file-shared w
486  in a distributed, decentralized and above all  in a distributed, decentralized and above all
487  *heterogeneous* way.  *heterogeneous* way.
488    
 .. XXX heterogeneous *how*?  
   
489  Using pointer records, we can provide the functionality  Using pointer records, we can provide the functionality
490  of static web pages. While dynamic web pages generated  of static web pages. While dynamic web pages generated
491  through server-side scripting and database connections  through server-side scripting and database connections

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