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File System

Henry Story edited this page Nov 23, 2013 · 1 revision

An initial implementation of the Linked Data Platform spec is implemented here. The same way as the Apache httpd server it servers resource from the file system and maps them to the web.

The file system

By default we map the test_www directory's content to https://localhost:8443/2013/.

The test_www directory starts with a few files to get you going

$ cd test_www
$  ls -al 
total 48
drwxr-xr-x   4 hjs  admin   340  9 Jul 19:04 .
drwxr-xr-x  15 hjs  admin  1224  9 Jul 19:04 ..
-rw-r--r--   1 hjs  staff   229  1 Jul 08:10 .acl.ttl
-rw-r--r--   1 hjs  admin   109  9 Jul 19:04 .ttl
lrwxr-xr-x   1 hjs  admin     8 27 Jun 20:29 card -> card.ttl
-rw-r--r--   1 hjs  admin   167  7 Jul 22:42 card.acl.ttl
-rw-r--r--   1 hjs  admin   896 27 Jun 21:41 card.ttl
-rw-r--r--   1 hjs  admin   102 27 Jun 22:32 index.ttl
drwxr-xr-x   2 hjs  admin   102 27 Jun 22:56 raw
drwxr-xr-x   3 hjs  admin   204 28 Jun 12:51 test

All files with the same initial name up to the . are considered to work together, (and in the current implementation are taken care of by the same agent).

Symbolic links are useful in that they:

  • allow one to write and follow linked data that works on the file system without needing to name files by their extensions. For example following the relation foaf:maker in the triple <> foaf:maker <card#me> will lead one to the <card> resource on the file system just as it does on the web.
  • they guide the web agent to which the default representation should be
  • currently they also help the web agent decide which are the resources it should serve.

There are three types of resources in this directory:

  • The symbolic links such as card distinguish the default resources that can be found by an http GET on http://localhost:8443/2013/card. Above the card -> card.ttl shows that card has a default turtle representation.
  • Each resource also comes with a Web Access Control List, in this example card.acl.ttl, which set access control restrictions on resources on the file system.
  • Directories store extra data (in addition to their contents) in the .ttl file. (TODO: not quite working)
  • Directories also have their access control list which are published in a file named .acl.ttl.

These conventions are provisional implementation decisions, and improvements are to be expected here . (TODO:

  • updates to the file system are not reflected yet in the server
  • allow symbolic links to point to different default formats )