constellation : Java Glossary

2008-08-09 by Roedy Green ©1996-2008 Canadian Mind Products
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constellation

A grouping of files to be processed, for example to be searched, indexed, tidied, macro-expanded…

A constellation has a way to specify which drives, directories, files and extensions to include and which drives, directories, files and extensions to exclude. This could be handled with lists, wildcards and/or regexes.

A constellation should have a name so that it can be specified and updated in one place, and referenced by a short name as a parameter to some utility.

Implementation

A constellation is a file itself. It is XML based to allow for extensions.

Unfortunately, the concept of constellation has not yet penetrated the programming world, so there is no uniform way to specify them, or reuse them in different programs. There is no standard DTD for the layout. This is primarily a political problem. Hint, hint. I invite you to share your ideas with me.

The definition of a standard constellation file format and constellation library would allow you to easily add filtering to any program designed to process just a single file. It would also the user to define a constellation once, and reuse it with a large number of different utilities.

How about some ideas on what the XML syntax for such a beast would look like? I could write a library to read it and let you then convert any single-file processing utility into a constellation-of-files processing utility. I will convert all my multi-file software to the new format and publish all source code. Maybe the idea will catch on. Here isz what a constellation file might look like:

It means, consider for backup the following files: All of the E:\mindprod directory tree. However, exclude the subtree kjv, and the subdirectory quadra (but not its subdirs). Exclude everything in the replicator subdirectory, however include all the *.html files except for the *log.html files which should be excluded. Also include all the z*.zip files in the replicator directory. Also consider the e:\com directory tree. Include all the *.java, *.html, *.txt and all the manifest.txt files. Finally include four files: E:/env/2008/taxreturn.xls, E:/env/secretpasswords.enc, E:/env/purchasedsoftwarekeys.txt and C:/personal/todo.txt.

Obviously the fine points of the grammar need to be sorted out, but that gives you the general picture.

Eventually you could have GUI tools to create them with check boxes. You could have a uniform pre-check to let you know just what files would be processed.

Constellation Utilities

If you use a standard constellation format, you can write some generic utilities to manipulate them:

checkbox: create a constellation by ticking off checkboxes of directories on Jtree of directories. You mark them as either include or exclude or individually. All the subdirs and files in a dir marked individually must be marked individually. If new dirs apper you must decide to make the constellion valid again. This lets non-technical people create constellations.
validate: check that the syntax is valid. It warns about missing files and directories. It is kosher to request files and directories be included on excluded that don’t exist yet.
explain: prints out what a constellation does in convoluted English.
union: join two constellations to extract the combined set of files.
intersection: join two constellations to extract what is common to both sets of files.
list: produce a sorted list of the files that are currently in the constellation.
backup: backup a list of files to DVD with a simple file-by-file copy.
sr: search/replace with regex.
space: tells you how many files and how much disk space a constellation takes.
zip: create/update a zip file with the constents of a constellation.

Examples of Existing Constellations

The Replicator requires a constellation of files to distribute to others. Compactor requires a constellation of files to compact. Untouch requires a constellation of directories to redate back if files have not really changed. HTML static macros requires a constellation of files composing a website that contain macros to be expanded. Xenu requires a constellation of files to be spidered to look for broken links. Funduc Search and Replace requires a constellation of files to search. Copernic Desktop Search requires a constellation of files to index. Backup progams need to define a constellation of file to back up. Typically they do it in an inept way so the raw list of files needs to be modified every time to account for new files is some of the directories.

FileDialog
JFileChooser
regex

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