[Gzz-commits] manuscripts/pointers article.rst

[Tuomas J. Lukka]

CVSROOT:        /cvsroot/gzz
Module name:    manuscripts
Branch:         
Changes by:     Tuomas J. Lukka <address@hidden>        03/11/04 05:03:27

Modified files:
        pointers       : article.rst 

Log message:
        Intro

CVSWeb URLs:
http://savannah.gnu.org/cgi-bin/viewcvs/gzz/manuscripts/pointers/article.rst.diff?tr1=1.121&tr2=1.122&r1=text&r2=text

Patches:
Index: manuscripts/pointers/article.rst
diff -u manuscripts/pointers/article.rst:1.121 
manuscripts/pointers/article.rst:1.122
--- manuscripts/pointers/article.rst:1.121      Tue Nov  4 04:49:37 2003
+++ manuscripts/pointers/article.rst    Tue Nov  4 05:03:27 2003
@@ -63,13 +63,13 @@
 no central point of failure for a Web page; it could be downloaded
 from any host that has a copy. This would save bandwidth
 and increase availability. However, if the Web worked like
-a filesharing system, Web pages could never be updated.
-
-Some filesharing systems offer URIs for files 
-(e.g., [freenet-ieee-andalso-edonkey2kurl]_).
-These URIs are based on the files' cryptographic hashes.
+a filesharing system, Web pages could not be updated easily.
+Some filesharing systems offer permanent URIs for files 
+(e.g., [freenet-ieee-andalso-edonkey2kurl]_),
+based on the files' cryptographic hashes.
 A new version of a Web page would have a different hash,
-and thus a different URI.
+and thus a different URI. Others could be confused by
+finding two files with the same name but different content (XXX).
 
 There are some (non-filesharing) P2P systems 
 that do offer an update mechanism. *CFS* [dabek01widearea]_
@@ -84,7 +84,7 @@
 
 In *OceanStore* [kubiatowicz00oceanstore]_, 
 an Internet-scale distributed data store that 
-allows users to keep their files save and access them 
+allows users to access their files 
 from different locations, every document has a 
 *primary replica*, a small set of servers that
 maintain the current version of the document.
@@ -93,15 +93,17 @@
 containing a document id, the hash of a version,
 a timestamp and a serial version number.
 To obtain the most current version, one sends a request
-to the primary replica. Many applications, however,
-are believed to be able to cope with looser consistency
-semantics; the NFS client for CFS only requests
-new heartbeats less than 30 seconds old.
+to the primary replica [#consistencytime]_. 
 OceanStore is unique among the versioned P2P systems
 in that it implements non-destructive updates,
 allowing previous versions of documents to be accessed
 (by using their old heartbeats).
 
+.. [#consistencytime] Many applications
+   are believed to be able to cope with looser consistency
+   semantics; for example, the NFS client for CFS only requests
+   new heartbeats less than 30 seconds old.
+
 *Freenet*, a P2P network for anonymous publication [freenet-ieee]_,
 was originally planned to have an
 update mechanism where the network would remember
@@ -149,9 +151,9 @@
 
 Thus, in these systems, when the original publisher loses interest
 and stops publishing a page, it disappears, even if
-someone else would have kept a copy.
+someone else has kept a copy.
 
-This is an important concern.
+This is an important concern, as seen by the following example.
 In 1997, NASA launched the Cassini-Huygens spacecraft
 on a mission to Saturn. Before the launch, the mission
 was widely criticized for its use of radioisotope
@@ -162,16 +164,17 @@
 SpaceViews, a publication of the National Space Society,
 published a list of links to web pages of both
 Cassini opponents and supporters [#rtg-links]_.
+In the year 2003,
+only six years after the launch, 
+only 29 
+of the 83 links provided by SpaceViews continue to work.
+Almost two thirds of the debate
+has fallen off the Web. "If I have seen further it is by standing
+on the shoulders of giants;" but how can we do that today,
+if the shoulders keep rotting away?
 
 .. [#rtg-links] ``http://www.seds.org/spaceviews/cassini/ rtgpages.html``.
    All links dereferenced on October 27th, 2003.
-
-
-Of the 83 links provided by SpaceViews, only 29 continue to work in 2003.
-Only six years after the launch, almost two thirds of the debate
-have fallen off the Web. "If I have seen further it is by standing
-on the shoulders of giants;" but how can we do that today,
-if the shoulders keep rotting away?
 
 (The Internet Archive's Wayback Machine [waybackmachine]_
 alleviates these concerns, but it introduces