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| author | Frank Baker <fbaker@hdfgroup.org> | 1999-07-02 02:54:33 (GMT) |
|---|---|---|
| committer | Frank Baker <fbaker@hdfgroup.org> | 1999-07-02 02:54:33 (GMT) |
| commit | a129c4d54ee930cc1dd5472177035d94cab19def (patch) | |
| tree | 6e700705df31689d73eb9f1b57bc7ad4fc7e2180 /doc/html/H5.format.html | |
| parent | 2e69c87e6bb087451a1bd80c0274ff35ab5de340 (diff) | |
| download | hdf5-a129c4d54ee930cc1dd5472177035d94cab19def.zip hdf5-a129c4d54ee930cc1dd5472177035d94cab19def.tar.gz hdf5-a129c4d54ee930cc1dd5472177035d94cab19def.tar.bz2 | |
[svn-r1404]
H5.format.html
Copy edits
Beginning of revisions to bring the Specification up-to-date and
move it to present tense
Couple of new intro paragraphs, designed largely to offer the
user a bit more context
H5.user.html
Datatypes.html
Font correction and minor formatting changes.
H5.user.PrintGen.html
H5.user.PrintTpg.html
New files to enable creating a searchable and printable version
of the HDF5 User's Guide. These files enable the creation of a
PDF file containing the entire document. H5.user.PrintGen.html
controls the print job; H5.user.PrintTpg.html is the title page
for the PDF volume.
Diffstat (limited to 'doc/html/H5.format.html')
| -rw-r--r-- | doc/html/H5.format.html | 93 |
1 files changed, 90 insertions, 3 deletions
diff --git a/doc/html/H5.format.html b/doc/html/H5.format.html index a098deb..59bc28d 100644 --- a/doc/html/H5.format.html +++ b/doc/html/H5.format.html @@ -4,7 +4,7 @@ HDF5 Disk-Format Specification </title> </head> - <body> + <body bgcolor="#FFFFFF"> <center><h1>HDF5: Disk Format Implementation</h1></center> <ol type=I> @@ -81,10 +81,97 @@ <P>The format of a HDF5 file on disk encompasses several key ideas of the current HDF4 & AIO file formats as well as - addressing some short-comings therein. The new format will be - more self-describing than the HDF4 format and will be more + addressing some short-comings therein. The new format is + more self-describing than the HDF4 format and is more uniformly applied to data objects in the file. + <P>An HDF5 file can be thought of as a directed graph. + The nodes of this graph are the higher-level HDF5 objects, + including groups, datasets, datatypes, and dataspaces. + This document describes the lower-level data objects used by + the HDF5 library to represent those higher-level objects and + their properties. + + <P>At the lowest level, an HDF5 file is made up of the following + objects: + <ul> + <li>A bool block + <li>B-tree nodes (containing either symbol nodes or raw data chunks) + <li>Object headers + <li>Collections + <li>Local heaps + <li>Free space + </ul> + As indicated above, the HDF5 library uses and interprets these + low-level objects to describe the high-level HDF5 objects that + are revealed to the user, and to higher-level applications, + through the HDF5 APIs. + +<!-- +<blockquote> +<pre> + +---------- Edit from here... ------------- + + +Once you know about all these low-level objects you can build bigger +and better things, which is what most people are interested in and +which are the objects that the hdf5 library exposes in the API. They +are: + + * Groups + * Datasets + * Datatypes + * Data spaces + +For instance, a group is an object header that contains a message that +points to a local heap and to a B-tree which points to symbol nodes. +A dataset is an object header that contains messages that describe +data type, space, layout, filters, external files, fill value, etc +with the layout message pointing to either a raw data chunk or to a +B-tree that points to raw data chunks. + +Elena> Would it be more logical to discuss things in this order? + +Elena> Intro ( What is HDF5 file, etc.) +Elena> File Header +Elena> File Body +Elena> Objects +Elena> Object Header +Elena> Object Header Message Data +Elena> NOTE: give reference to the detailed discussion of the B-trees +Elena> when needed. Right now we do not have specification (only general one) +Elena> for the Symbol Table B-trees and B-trees used to manage chunked datasets. +Elena> B-trees +Elena> General Discussion +Elena> Object related discussions +Elena> Symbol Tables +Elena> Global heap +Elena> "Free-space object" + +That might be a good order for someone that's familiar with the API +but if you're trying to get all the way down to the file format level +it results in a lot of forward references in the documentation. It +might be better to do a bottom-up documentation similar to the order I +used above: + + * General file layout + * Boot block + * Format-level objects (B-trees, symbol nodes, object headers, etc). + * Object header messages + * High-level objects (datasets, groups, named types and spaces, etc) + +where "high-level objects" description mostly describes which object +header messages are required, optional, mutually exclusive, etc. for +each high-level object. + +---------- ...to here. ------------- + +</pre> +</blockquote> +--> + + <P>Three levels of information compose the file format. The level 0 contains basic information for identifying and |