Versions Compared

Old Version 2

changes.mady.by.user Unknown User (akbar)

Saved on

compared with

New Version 3

changes.mady.by.user Unknown User (akbar)

Saved on

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

...

  1. FreezeThaw, written by Ilya Zakharevich, is a pure Perl module (no C extensions) and encodes complex data structures into printable ASCII strings.
  2. Data::Dumper, written by Gurusamy Sarathy, is similar in spirit to FreezeThaw, but takes a very different approach. Still implemented in Perl though. Also it basically pretty prints the data structure so it is not of much use for marshalling and unmarshalling.
  3. Storable is a C extension module for serializing data directly to files and is the fastest of the three approaches.

(For an indepth discussion of the streamed approaches you may refer to http://www.unix.org.ua/orelly/perl/advprog/ch10_02.htm)

For the Record-Oriented Approaches, once again there are three implementations:

  1. DBM is a disk-based hash table, originally written by Ken Thompson for the Seventh Edition Unix system.
  2. MLDBM (multilevel DBM) stores complex values in a DBM file. It uses Data::Dumper to serialize any data structures, and uses a DBM module of your choice.
  3. Berkeley DB - is a public-domain C library of database access methods, including B+Tree, Extended Linear Hashing, and fixed/variable length records. The latest release also supports concurrent updates, transactions, and recovery.

(For a more detailed discussion of these you of record based approached you may refer to http://www.unix.org.ua/orelly/perl/advprog/ch10_03.htm)

Choice of Technique:

Since I am implementing a simple checkpointing mechanism which is not only easy to implement but also efficient, I am currently working with the streamed approaches as I donot require the elaborate transaction recovery functionality present in the record based approaches.

Within the stream based approaches 'Storable' is an attractive option since:

  1. It is the only approach which allows you to directly serialize the nested hash strcture to file and back through a seamless interface.
  2. It is implemented in C which should give some performance advantage over the other two modules implemented in Perl.

 I have already tested this approach in JKFlow and it successfully marshalls the