perl-Digest-TransformPath - Implements the TransformPath concept

Property Value
Distribution ALT Linux Sisyphus
Repository Autoimports noarch
Package filename perl-Digest-TransformPath-1.00-alt1.noarch.rpm
Package name perl-Digest-TransformPath
Package version 1.00
Package release alt1
Package architecture noarch
Package type rpm
Category Development/Perl
Homepage -
License -
Maintainer -
Download size 30.40 KB
Installed size 30.40 KB
A TransformPath is a complex higher-order key that is designed for use with
chains of functions that sequentially transform a piece of data.
The concept starts with a sizable chunk of data, for example an image, for
which we can determine a unique identifier, and for which we can cheaply
determine if and when the source material has changed.
A series of resource-intensive transforms might be applied to this original
data to produce another piece of data. In the image example, we might
auto-level, crop, scale, rotate, colour-balance and then thumbnail the
image. This transformed data would be put into a cache.
If at some future point we wish to obtain the same image, but would
preferably like to use the cached version, we would have to take the original
image, reapply the transforms, and then compare to the result the first time
Alternatives to this general checking mechanism revolve around storing the
identifier in parellel to the data file, in a database or data file, or
similar schemes the involve similar amounts of complexity.
In the TransformPath concept, a structure is created which contains the
original source identifier, and a short, ordered and unique description of
all of the transformations in the sequence.
This description structure is then serialised and hashed to get a unique and
generally cryptographically secure identifier for the transformed image. This
identifier would typically be used as part of the file name/path for the
transformed image.
To check that the file is unchanged, we merely confirm that the original has
not changed, and then rebuilt the TransformPath digest. If the TransformPath
digest is unchanged, then the transformed image is unchanged, and we can use
the version in the cache, saving ourselves the high expense of running the
transforms again.
If we cannot cheaply tell that the source image has changed, there is a
clean fallback position. By including a digest of the original data inside
the TransformPath object, the final digest changes automatically whenever the
data inside the source file changes.
While this still costs us a digest run each time, this is relatively
affordable compared to doing the transforms as well.
This can be done by either using the initial digest as the source id, or by
adding it as the first transform step. The latter is recommended for most
situations, as this ensures that the source id is static, and won't change.
In many uses of Digest::TransformPath, this is likely to be highly preferable.


Package Version Architecture Repository
perl-Digest-TransformPath - - -


Name Value
/usr/share/perl5 -
perl(Digest/ >= 2.0
rpmlib(PayloadIsLzma) -


Name Value
perl(Digest/ = 1.0
perl-Digest-TransformPath = 1.00-alt1


Type URL
Binary Package perl-Digest-TransformPath-1.00-alt1.noarch.rpm
Source Package perl-Digest-TransformPath-1.00-alt1.src.rpm

Install Howto

  1. Add the following line to /etc/apt/sources.list:
    rpm [Sisyphus] noarch autoimports
    rpm [Sisyphus] noarch autoimports
  2. Update the package index:
    # sudo apt-get update
  3. Install perl-Digest-TransformPath rpm package:
    # sudo apt-get install perl-Digest-TransformPath



See Also

Package Description
perl-Digest-UserSID-1.05-alt1.noarch.rpm Managing of Session IDs for Users on CGI- and console-scripts
perl-Digest-combined-0.1-alt1.noarch.rpm Calculate multiple message digests simultaneously
perl-Digest-ssdeep-0.9.3-alt1.noarch.rpm Pure Perl ssdeep (CTPH) fuzzy hashing
perl-Digital-0.002-alt1.noarch.rpm Handling conversion of digital values towards physical units
perl-Digital-scripts-0.002-alt1.noarch.rpm Digital scripts
perl-DigitalOcean-0.14-alt1.noarch.rpm An OO interface to the Digital Ocean API
perl-Dios-0.002011-alt1.noarch.rpm Declarative Inside-Out Syntax
perl-Dir-Iterate-0.02-alt1.noarch.rpm map and grep for directory trees
perl-Dir-List-1.4-alt1.noarch.rpm perl module Dir-List
perl-Dir-ListFilesRecursive-0.05-alt1.noarch.rpm Static functions to find files in directories
perl-Dir-Manifest-0.2.0-alt1.noarch.rpm treat a directory and a manifest file as a hash/dictionary of keys to texts or blobs
perl-Dir-Project-3.026-alt1.noarch.rpm Determine utility paths relative to version controlled directories
perl-Dir-Project-scripts-3.026-alt1.noarch.rpm Dir-Project scripts
perl-Dir-Purge-1.02-alt1.noarch.rpm perl module Dir-Purge
perl-Dir-Rocknroll-0.34-alt1.noarch.rpm Rsync fOr baCKup and Roll