This page documents how FreshPorts can use the 404 error process to serve up virtual pages.
It is assumed that the reader is familiar with the FreeBSD ports tree and how it works.
The FreeBSD ports tree contains several thousand port skeletons. These skeletons are used to download, compile, and installed software from source. For ease of use, these ports are divided into different directories called categories.
FreshPorts uses the PostgreSQL RDBMS.
FreshPorts allows a user to broswe through the website in much the same way as they might move around in a directory tree. In effect, the website mirrors what the user might find on disk but with enhanced information and presentation.
For example, on disk the user would find the following:
[dan@m20:/usr/ports] $ ls INDEX distfiles news INDEX-5 editors palm INDEX.db emulators picobsd LEGAL finance portuguese MOVED french print Makefile ftp russian Mk games science README german security Templates graphics shells Tools hebrew sysutils archivers hungarian textproc astro irc ukrainian audio japanese vietnamese benchmarks java www biology korean x11 cad lang x11-clocks chinese mail x11-fm comms math x11-fonts converters mbone x11-servers databases misc x11-toolkits deskutils multimedia x11-wm devel net [dan@m20:/usr/ports] $
Most of the above directories are categories. Exceptions include INDEX, Mk, and README. For this dicussion, we will ignore the non-categories which appear in the /usr/ports directory.
For example, the shells directory contains:
None of the above directories actually appear on the webserver. The website takes advantage of the ErrorDocument directive in the Apache webserver. This is the entry found within the FreshPorts website definition:[dan@m20:/usr/ports/shells] $ ls 44bsd-csh mudsh scponly Makefile nologinmsg tcsh bash1 osh vshnu bash2 pash wapsh es pdksh zsh esh perlsh zsh+euc_hack fd pkg zsh-devel flash rc ksh93 sash [dan@m20:/usr/ports/shells] $
Should an page be requested which is not found,ErrorDocument 404 /missing.php
missing.phpis invoked. The code within this page determines which category and/or port is being requested. This is accomplished using
$_SERVER['REQUEST_URI']and database queries to establish which category and/or port is being requested.
The process used to determine the category and/or port needs to be improved and simplified. The process can be express by this pseudo-code:
read list of categories IF category exists THEN IF port name is supplied THEN IF port exists THEN display details for port ELSE display 'port not found' page END IF ELSE display ports within this category END IF ELSE display 'category not found' page END IF
Here is entry from the Makefile for databases/zpygresqlda which specifies the categories for that port:
CATEGORIES= databases www zope
The first category listed is the subdirectory which contains the files for this port. The other categories may be either real or virtual, but the first category must always be the real or physical directory.
The physical directory for each port is stored within the ports table.
The table also contains a
categories field which contains the value
extracted from the Makefile (e.g. for this port, the field would contain
databases www zope). Have a look at
databases/zpygresqlda to see how this
information is used. Look for the entry titled Also listed in.
The proposed solution for
portstable and a
categoriestable. The system caters for a port which resides within one physical category but does not cater for virtual categories. In brief, these tables look like this:
Field name type id int name text is_primary boolean
Field name type id int category_id int
category_id field in the
ports table contains
a foreign key reference to the
ports_categorywhich will look similar to this:
Field name type referential integrity port_id int linked to ports table category_id id linked to categories table
For databases/zpygresqlda, there will be three entries in this table, one for each category.
This table will be populated via a rule (as opposed to a trigger) on the ports table. For each update, insert, and delete on the ports table, the rule will amend the ports_category table accordingly.
The same rule could be used to maintain the
categories table. This would
ensure that new virtual categories are added/removed as/when necessary.
This solution should make it fairly each to serve up virtual categories. More investigation is needed to consider the possible implications for other parts of the system.
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