Author: j16sdiz
Date: 2009-02-27 14:00:37 +0000 (Fri, 27 Feb 2009)
New Revision: 25853
Modified:
trunk/freenet/devnotes/specs/metadata-v0.txt
Log:
some (incomplete) doc update
Modified: trunk/freenet/devnotes/specs/metadata-v0.txt
===================================================================
--- trunk/freenet/devnotes/specs/metadata-v0.txt 2009-02-27 14:00:05 UTC
(rev 25852)
+++ trunk/freenet/devnotes/specs/metadata-v0.txt 2009-02-27 14:00:37 UTC
(rev 25853)
@@ -11,6 +11,7 @@
size, metadata of any conceivable size, ZIP manifests and ordinary
manifests. Limits will be imposed at the client level. Comments?
+All numbers are in java big-endian.
8 bytes - magic number for freenet metadata
Wasted bytes, just being paranoid.
@@ -19,78 +20,73 @@
0 for now.
1 byte - document type
-0 = simple redirect (including splitfiles)
-1 = multi-level metadata (fetch this key, then use it as metadata)
-2 = ordinary manifest
-3 = ZIP manifest
-4 = reserved for use in ZIP manifests, see below
-5+ = available
+ 0 = SIMPLE_REDIRECT - simple redirect (including splitfiles)
+ 1 = MULTI_LEVEL_METADATA - multi-level metadata (fetch this key, then
use it as metadata)
+ 2 = SIMPLE_MANIFEST - ordinary manifest
+ 3 = ARCHIVE_MANIFEST - ZIP/TAR manifest
+ 4 = ARCHIVE_INTERNAL_REDIRECT - reserved for use in ZIP/TAR manifests, see
below
-If multi-level metadata:
+If documentType == MULTI_LEVEL_METADATA:
1 byte - number of levels (must decrease by 1 on each level!)
1 byte - document type of final metadata
8 bytes - length of final data
-For a simple redirect, multi-level metadata, or a ZIP manifest:
+If documentType == SIMPLE_REDIRECT or SIMPLE_MANIFEST or ARCHIVE_MANIFEST or
ARCHIVE_INTERNAL_REDIRECT
+ 2 bytes - flags
+ bit 0 = FLAGS_SPLITFILE - splitfile
+ bit 1 = FLAGS_DBR - DBR (splitfile + DBR *is* valid, not
supported)
+ bit 2 = FLAGS_NO_MIME - no MIME type
+ bit 3 = FLAGS_COMPRESSED_MIME - compressed MIME type
+ bit 4 = FLAGS_EXTRA_METADATA - has extra metadata fields (ignored)
+ bit 5 = FLAGS_FULL_KEYS - redirects as full keys (invalid if
splitfile)
+ bit 6 = FLAGS_SPLIT_USE_LENGTHS - reserved/unused
+ bit 7 = FLAGS_COMPRESSED - compressed splitfile
-2 bytes - flags
-bit 0 = splitfile
-bit 1 = DBR (splitfile + DBR *is* valid)
-bit 2 = no MIME type
-bit 3 = compressed MIME type
-bit 4 = has extra metadata fields
-bit 5 = redirects as full keys (invalid if splitfile)
-bit 6 = unused
-bit 7 = compressed splitfile (might work with normal redirects but there
-is no point as single blocks are transparently gzipped anyway)
+If documentType == ARCHIVE_MANIFEST:
+ 2 bytes - ARCHIVE_TYPE
+ 0 = ZIP ("application/zip", "application/x-zip") /* eventually get rid of
ZIP support at some point */
+ 1 = TAR ("application/x-tar")
-If a ZIP manifest:
-2 bytes - archive ID (initially 0 = ZIP. We may in future support 1 =
-tar, with the compressed splitfile bit set, and then a codec specified
-below, for tar.gz, tar.bz2 etc)
+If flags |= FLAGS_SPLITFILE:
+ 8 bytes - real content length (compressed size, signed number)
-If a splitfile:
-8 bytes - real content length (uncompressed)
-Note no 2GB limit. :)
+If flags |= FLAGS_COMPRESSED:
+ 2 bytes - COMPRESSOR_TYPE
+ 0 = GZIP
+ 1 = BZIP2
+ 2 = LZMA
+ 8 bytes - decompressed content length (signed number)
-If compressed:
-2 bytes - codec ID
-Initially we only support gzip (0).
-8 bytes - decompressed content length
+If _NOT_ flags |= FLAGS_NO_MIME:
+ If flags |= FLAGS_COMPRESSED_MIME:
+ 2 bytes - compressedMIMEValue (base MIME type IDs)
+ See DefaultMIMETypes.java for the look up table
-If has a MIME type:
-If raw:
-1 byte - length (N)
-N bytes - string
+ If compressedMIMEValue & 0x7fff == 0x7fff:
+ 2 bytes - compressedMIMEParams
+ else
+ 1 byte - length (N)
+ N bytes - MIME Type (UTF-8 String)
-If compressed:
-2 bytes - base MIME type ID; index into lookup table; last bit is not
- part of the lookup index, and defines whether parameters are necessary.
-2 bytes - if parameters are expected, parameters ID (mostly charset= for
- text/ types; other types may define other parameters)
+If flags |= DBR: (not supported yet)
+ 4 bytes - period, in seconds
+ 4 bytes - offset, in seconds
+If flags |= FLAGS_EXTRA_METADATA: (ignored)
+ 2 bytes - number of extra metadata fields
+ For each extra metadata field:
+ 2 bytes - metadata field type
+ 1 byte - length
+ N bytes - metadata field specific information
-If DBR:
-4 bytes - period, in seconds
-4 bytes - offset, in seconds
-If has extra metadata fields:
-2 bytes - number of extra metadata fields
+If (!(flags |= FLAGS_SPLITFILE) && ((documentType == SIMPLE_REDIRECT) ||
(documentType == ARCHIVE_MANIFEST)):
+ If FLAGS_FULL_KEYS
+ 1 byte - length of binary key
+ N bytes - binary key (this is just a compressed FreenetURI, see
FreenetURI.java)
+ Else
+ 5+32+32 bytes - raw binary form of a CHK
-For each:
-2 bytes - metadata field type
-1 byte - length
-N bytes - metadata field specific information
-
-
-For a simple redirect:
-
-If bit 5 is set above:
-1 byte - length of binary key
-N bytes - binary key (this is just a compressed FreenetURI)
-Else:
-<fixed number yet to be determined> bytes - raw binary form of a CHK
-
For a splitfile redirect:
2 bytes - algorithm ID
0 = no redundancy. Invalid unless bit 6 or 5 above is set.
_______________________________________________
cvs mailing list
[email protected]
http://emu.freenetproject.org/cgi-bin/mailman/listinfo/cvs
