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| HowTo Linux Zone | Linux Zone Home | E-Mail Me | A mSQL and perl Web Server Mini HOWTO Oliver Corff, corff@zedat.fu-berlin.de
v0.1, 17 September 1997
This Mini HOWTO, highly inspired by Michael Schilli's article
Gebunkert: Datenbankbedienung mit Perl und CGI, published in the ger­
man computer magazine iX 8/1997, describes how to build a SQL
client/server database using WWW and HTML for the user interface.
1. About this Document
1.1. Intended Audience
Everybody who wants to install a web server database but does not know
which software is necessary and how it is installed should benefit
from reading this text. This text provides all information necessary
to get a SQL database for a web server going; it does not go into any
detail of CGI programming, nor does it explain the SQL database
language. Excellent books are available on both topics, and it is the
intention of this text to provide a working platform based on which a
user can then study CGI programming and SQL.
For getting a small scale SQL system running (not the notorious
example of a major airline booking system, or space mission management
database) it will be sufficient to have the software described in this
text and the documentation accompanying it. The user manual of msql (a
database introduced in this text) provides sufficient information on
SQL for building your own database.
The reader of this text should have a working knowledge of how to
obtain files via ftp if he has no access to CD-ROMs, and a basic
understanding of how to build binaries from sources. Anyway, all steps
explained in this text were tested on a real life system and should
also work on the reader's system.
1.2. Conventions used in this text
A user command:
# make install
Screen output from a program:
Program installed. Read README for details on how to start.
Sample code of a file:
______________________________________________________________________
# My comment
char letter;
______________________________________________________________________
2. Introduction
It can be safely assumed that databases with a high volume of data or
a complicated relational setup (like, perhaps, a lexical database for
a living language) must be accessible to many users and operators at
the same time. Ideally, it should be possible to use existing
different hardware and software platforms that can be combined into
the actual system. In order to reduce the implementation cost, only
one system, the database server, needs to be powerful; the user
stations typically just display data and accept user commands, but the
processing is done on one machine only which led to the name client-
server database. In addition, the user interface should be easy to
maintain and should require as little as possible on the client side.
A system which meets these criteria can be built around the following
items of protocols, concepts and software:
Linux
supplies the operating system. It is a stable Unix
implementation providing true multi-user multi-tasking services
with full network (TCP/IP e. a.) support. Except from the
actual media and transmission cost, it is available free of
charge and comes in form of so-called distributions which
usually include everything needed from the basic OS to text
processing, scripting, software development, interface builders,
etc.
HTML
is the Hypertext Markup Language used to build interfaces to
network systems like Intranets and the WWW, the World Wide Web.
HTML is very simple and can be produced with any ASCII-capable
text editor.
Browsers
are text-based (e. g. Lynx) or graphical (e. g. Mosaic,
Netscape, Arena etc.) applications accepting, evaluating and
displaying HTML documents. They are the only piece of software
which is directly operated by the database user. Using browsers,
it is possible to display various types of data (text, possibly
images) and communicate with http servers (see next) on about
every popular computer model for which a browser has been made
available.
http servers
provide access to the area of a host computer where data
intended for public use in a network are stored. They understand
the http protocol and procure the information the user requests.
SQL
Structured Query Language is a language for manipulating data in
relational databases. It has a very simple grammar and is a
standard with wide industry support. SQL-based databases have
become the core of the classical client/server database concept.
There are many famous SQL systems available, like Oracle,
Informix etc., and then there is also msql which comes with a
very low or even zero price tag if it is used in academical and
educational environments.
CGI
Common Gateway Interface is the programming interface between
the system holding the data (in our case an SQL-based system)
and the network protocol (HTML, of course). CGIs can be built
around many programming languages, but a particularly popular
language is perl.
perl
is an extremely powerful scripting language which combines all
merits of C, various shell languages, and stream manipulation
languages like awk and sed. Perl has a lot of modularized
interfaces and can be used to control SQL databases, for
example.
3. Installation Procedure
3.1. Hardware Requirements
No general statement can be made about the hardware requirements of a
database server. Too much depends on the expected number of users, the
kind of application, the network load etc. In a small environment with
only a few users and little network traffic a i486-equivalent machine
with 16 MB of RAM can be completely sufficient. Linux, the operating
system, is very efficient in terms of resources, and can supply enough
horse-power for running a broad variety of applications at the same
time. Of course, faster processors and more RAM mean more speed, but
much more important than the processor is the amount of RAM. The more
RAM the system has the less it is forced to swap memory intensive
processes to disk in case a bottleneck occurs.
Given anything like 32 MB RAM and a PCI bus, searches and sorting
operations can be done without much resorting to swap files etc.,
resulting in lightening fast speed.
The model installation described in this article was made on a IBM 686
(133Mhz) with 32 MB RAM and a 1.2 GB IDE hard disk. Assuming that the
installation process starts from scratch, here is a list of the
necessary steps.
3.2. Software Requirements
The software described in this article is available from the Internet
or from CD-ROM. The following products were used:
· Red Hat Linux PowerTools: 6 CD's Complete Easy-to-Use Red Hat 4.2,
Summer '97; alternatively from http://www.redhat.com;
· msql SQL database server: it is now available in two versions. The
versions have differences in the number of transactions they can
handle, the administration interface, etc. The elder version,
1.0.16, is available from Sunsite mirrors. The ELF executable can
be found at sunsite:apps/database/sql/msql-1.0.16 or on CD-ROM
(here: disc 4 of InfoMagic Linux Developer's Resource, 6-CD set,
December 1996) or alternatively from the following URL:
http://www.infomagic.com.
The newer version, 2.0.1, can be directly obtained from Hughes'
homepage in Australia (http://www.hughes.com.au) or from numerous
mirror sites around the world;
· perl from CPAN: The Comprehensive Perl Archive Network. Walnut
Creek CDROM, ISBN 1-57176-077-6, May 1997;
· Michael Schilli's CGI example program from computer journal iX
8/1997, pages 150--152, available via ftp from ftp.uni-
paderborn.de:/doc/magazin/iX;
3.3. Installing the Operating System
Linux is installed in form of the Red Hat Linux Distribution 4.2. In
order to install successfully, the machine must either have a DOS-
accessible CD-ROM drive, a bootable CD-ROM drive, or else a boot disk
must be made following the instructions on the Linux CD.
During installation the user has the choice to select and configure
numerous software packages. It is convenient to select the following
items now:
· TCP/IP network support,
· the http server Apache, and
· the scripting language perl, and
· the X Window System, as well as
· the browsers Arena (graphical) and Lynx (text-based).
All these packages are provided with the Linux distribution. If you
do not install these packages now you still have the chance to do this
later with the assistance of glint, the graphical and intuitive
software package installation manager. Be sure to be root when
installing these packages.
It is beyond the scope of this article to describe the network
installation and initialization procedure. Please consult the online
(manpages, HTML, texinfo) and printed (Linux Bible, etc. etc.)
documentation.
The installation procedure of Red Hat is very mature and requires only
little user attention besides the usual choices (like providing host
names, etc.). Once the installation ends successfully, the system is
basically ready to go.
Installing the X Window System is not mandatory for a pure server but
it makes local access and testing much easier. The X installation
procedure is done by any of several programs; XF86Setup offers the
most extensive self-testing facilities and needs the least handling of
hairy details (like video clock programming, etc.). The only
requirement is that the software can detect the video adapter. A cheap
accelerated graphics adapter (like Trio S64 based cards prior to
S64UV+) usually works ``out of the box''.
At this point we assume that our system is up and running and that
Apache, Perl and the X Window System have been successfully installed.
We further assume that all standard structures like the file and
directory structure are kept as they are defined in the installation.
Last but not least we leave the host name as it is, and do at this
moment accept the name localhost. We'll use this name for testing the
installation; once the whole system works the true name can be added.
Please note that the network setup also requires editing the files
/etc/hosts, among others. Ideally this should be done with the
administration tools provided to user root.
3.4. The http Server
The http server supplied with Linux is known as Apache to humans and
as httpd to the system. The manpage (man httpd) explains how to
install and start the http daemon (hence httpd) but, as mentioned, if
the installation went without problems then the server should be
running. You can verify the directory tree: there must be a directory
/home/httpd/ with three subdirectories: ../cgi-bin/, be a file
index.html. Later we will manipulate or replace this file by our own
index.html. All configuration information is stored
in/etc/httpd/conf/. The system is well preconfigured and does not need
further setup provided the installation went without error.
3.5. The Browsers
There are essentially three types of browsers available for Linux:
pure text-based systems like Lynx, experimental and simple ones like
Arena (free!) and commercial ones like Netscape (shareware!) with Java
support. While Lynx and Arena come with Linux, Netscape must be
procured from other sources. Netscape is available as a precombiled
binary for Linux on ix86 architectures and will run ``out of the box''
as soon as the archive is unpacked.
3.5.1. Configuring Lynx
Once Lynx is started it will look for a `default URL' which is usually
not very meaningful if the system does not have permanent Internet
access. In order to change the default URL (and lots of other
configuration details) the system administrator should edit
/usr/lib/lynx.cfg. The file is big, around 57000 bytes and contains
occasionally contradicting information. It states its own home as
/usr/local/lib/. Not far from top is a line beginning with STARTFILE.
We replace this line by the following entry:
STARTFILE:http://localhost and make sure that no spacing etc. is
inserted:
______________________________________________________________________
# STARTFILE:http://www.nyu.edu/pages/wsn/subir/lynx.html
STARTFILE:http://localhost
______________________________________________________________________
After saving the file, Lynx should now reveal our index.html document
if started without arguments.
3.5.2. Configuring Arena
Arena first looks for its own default URL when started without
arguments. This URL is hard-wired into the executable but can be
overrun by the environment variable WWW_HOME. The system administrator
can place a line saying WWW_HOME="http://localhost" in /etc/profile.
The variable must then be exported, either by a separate statement
(export WWW_HOME) or by appending WWW_HOME to the existing export
statement:
______________________________________________________________________
WWW_HOME="http://localhost"
export WWW_HOME
______________________________________________________________________
After relaunching a login shell, the new default URL is now system-
wide known to Arena.
3.5.3. Installing and Configuring Netscape
Netscape is a commercial product and thus not included with the Linux
distributions. It is either downloadable from the Internet or
available from software collections on CDROM. Netscape comes in form
of precompiled binaries for every important hardware platform. For
installation purposes, it is useful to create a directory
/usr/local/Netscape/ where the archive is unpacked. The files can be
kept in place (except for the Java library: follow the instructions in
the README file that comes with the Netscape binary), and it is
sufficient to create a soft link in /usr/local/bin/ by issuing the
command
# ln -s /usr/local/Netscape/netscape .
from within /usr/local/bin/.
Netscape is now ready for use and can be configured via the
``Options'' menu. In ``General Preferences'' there is a card
``Appearance'' with the entry ``Home Page Location''. Enter
http://localhost here and do not forget to save the options (via
``Options'' --- ``Save Options'') before exiting Netscape. At the next
startup, Netscape will now show the Apache `homepage'.
3.6. Cooperation of Apache and Browsers
You can now conduct the first real test of both the browser and the
http server: simply start any of the available browsers and the
Apache: Red Hat Linux Web Server page will pop up. This page shows
the file locations and other basics of http server installation. If
this page is not displayed please check whether the files mentioned
above are in place and whether the browser configuration is correct.
Close edited configuration files before you start the browser again.
If all files are in place and the browsers seem to be configured
correctly then examine the network setup of your machine. Either the
host name is different from what was entered in the configuration, or
the network setup as such is not correct. It is utterly important that
/etc/hosts contains at least a line like
______________________________________________________________________
127.0.0.1 localhost localhost.localdomain
______________________________________________________________________
which implies that you can connect locally to your machine. One can
verify this by issuing any network-sensitive command requiring a host
name as argument, like telnet localhost (provided telnet is
installed). If that does not work then the network setup must be veri­
fied before continuing with the main task.
3.7. The Database Engine and its Installation
Installing the database requires only little more preparation than the
previous installation steps. There are a few SQL database engines
available with different runtime and administrative requirements, and
possibly one of the most straightforward systems is msql, or ``Mini-
SQL'' by David Hughes. msql is shareware. Depending on the version
used, commercial sites are charged USD 250.00 and more, private users
are charged USD 65.00 and more, and only educational institutions and
registered non-profit organizations can use this software free of
charge. Please note that the exact figures are provided in the
licence notes of the database documentation. The figures given here
serve as a rough indicator only.
A few words are in place here why the author chose msql. First of all,
there is personal experience. While searching for a database engine
the author found msql to be about the easiest to install and maintain,
and it provides enough coverage of the SQL language to meet general
needs. Only when writing these lines, the author discovered the
following words of praise in Alligator Descartes' DBI FAQ (perl
database interface FAQ):
From the current author's point of view, if the dataset is
relatively small, being tables of less than 1 million rows,
and less than 1000 tables in a given database, then mSQL is
a perfectly acceptable solution to your problem. This
database is extremely cheap, is wonderfully robust and has
excellent support. ...
Msql is available in two versions now, msql-1.0.16 and msql-2.0.1,
which differ in performance (not noticeable in small scale projects)
and accompanying software (the newer version comes with more tools,
its own scripting language, etc.). We will describe both versions of
msql since their installion differs in a few points.
3.7.1. Installing msql-1.0.16
msql is available as source and as compiled executable with ELF
support. Using the ELF binaries makes installation easy since the
archive file msql-1.0.16.ELF.tgz contains a complete absolute
directory tree so that all directories are generated properly when
unpacked from /.
If you decide to compile msql-1.0.16 yourself and are going to use the
MsqlPerl package rather than the DBI interface (see a detailed
discussion on the difference between these two further down) then be
prepared that MsqlPerl might complain during the test suites that some
instruction inside msql failed. In this case a patch may be necessary
which is described in the MsqlPerl documentation (file
patch.lost.tables). Notably, this demands including three lines in
msqldb.c after line 1400 which says entry->def = NULL;:
*(entry->DB) = 0;
*(entry->table) = 0;
entry->age = 0;
The code fragment should now look like
______________________________________________________________________
freeTableDef(entry->def);
safeFree(entry->rowBuf);
safeFree(entry->keyBuf);
entry->def = NULL;
*(entry->DB) = 0;
*(entry->table) = 0;
entry->age = 0;
______________________________________________________________________
Compiling msql involves several steps. After unpacking the source
archive, it is necessary to build a target directory. This is done by
saying
# make target
If successful, the system will then answer with
Build of target directory for Linux-2.0.30-i486 complete
You must now change into this newly created directory and run a
# ./setup
command first. The ./ sequence is necessary to make sure that really
the command setup in this directory and not another command which hap­
pens to have the same name is executed. You will then be asked ques­
tions on the location of the source directory and whether a root
installation is desired. These questions answered, the system should
then run a number of tests checking for available software (compilers,
utilities etc.) and finally say
Ready to build mSQL.
You may wish to check "common/site.h" although the defaults should be
fine. When you're ready, type "make all" to build the software
We say
# make all
If everything went as intended, we'll read:
make[2]: Leaving directory `/usr/local/Minerva/src/msql'
<-- [msql] done
Make of mSQL complete.
You should now mSQL using make install
NOTE : mSQL cannot be used free of charge at commercial sites.
Please read the doc/License file to see what you have to do.
make[1]: Leaving directory `/usr/local/Minerva/src'
All binaries must then be made visible to the search paths by creating
soft links in /usr/local/bin/. Change to that directory and issue the
command
# ln -s /usr/local/Minerva/bin/* .
after which the links will be properly set.
3.7.2. Testing msql-1
After the installation it is now possible to test whether the database
works. Before anything else is done, the server daemon must be
started. The system administrator holding root privileges issues the
command
# msqld &
(do not forget to add the &, otherwise msql won't run in the back&SHY;
ground.) after which the following screen message appears:
mSQL Server 1.0.16 starting ...
Warning : Couldn't open ACL file: No such file or directory
Without an ACL file global access is Read/Write
This message tells us that everything so far worked since we did not
set up any access restrictions. For the moment it is sufficient to
start the msql daemon from within a shell but later we may want to
have the system startup automatically execute this command for us.
The command must then be mentioned in a suitable rc.d script. Only
now the administrator can issue the first genuine database command:
# msqladmin create inventur
msql replies by saying Database "inventur" created.. As a further
proof, we find that the directory /usr/local/Minerva/msqldb/ contains
now the empty subdirectory ../inventur/. We could manipulate the newly
created database with the administration tools; these procedures are
all covered in detail in the msql documentation.
3.7.3. Installing msql-2.0.1
There is now a newer, more powerful version of Hughes' mSQL server
available the installation of which is different in a few points.
Installing msql-2 from scratch involves the following steps. Copy the
archive to your extraction point, e. g. /usr/local/msql-2/, then
untar the archive:
# tar xfvz msql-2.0.1.tar.gz
Change to the root direction of the install tree and issue a
# make target
Change to targets and look for your machine type. There should be a
new subdirectory Linux-(your version)-(your cpu)/. Change to that
directory and start the setup facility located here:
# ./setup
There is also a file site.mm which can be edited. Maybe you have got
used to the directory name /usr/local/Minerva/ and want to preserve
it? In this case change the INST_DIR=... line to your desired target
directory. Otherwise, leave everything as it is.
Now you can start building the database:
# make
# make install
If everything went successfully, we'll see a message like:
[...]
Installation of mSQL-2 complete.
*********
** This is the commercial, production release of mSQL-2.0
** Please see the README file in the top directory of the
** distribution for license information.
*********
After all is installed properly we have to take care of the
administration details. Here, the real differences from msql-1 begin.
First, a user msql is created which is responsible for database
administration.
# adduser msql
Then we have to change all ownerships in the mSQL directory to msql by
saying:
# cd /usr/local/Minerva
# chown -R msql:msql *
Then we create soft links for all database binaries in /usr/local/bin/
by saying:
# ln -s /usr/local/Minerva/bin/* .
3.7.4. Testing msql-2
We can now start the database server by issuing the command msql2d &
and should get a response similar to this one:
Mini SQL Version 2.0.1
Copyright (c) 1993-4 David J. Hughes
Copyright (c) 1995-7 Hughes Technologies Pty. Ltd.
All rights reserved.
Loading configuration from '/usr/local/Minerva/msql.conf'.
Server process reconfigured to accept 214 connections.
Server running as user 'msql'.
Server mode is Read/Write.
Warning : No ACL file. Using global read/write access.
That looks perfect. The database is compiled and in place, and we can
now continue with the perl modules since these rely partially on the
presence of a working database server for testing.
Accidentally, this is also a good moment to print the complete manual
that comes with msql-2.0.1:
# gzip -d manual.ps.gz
# lpr manual.ps
We can proceed to building the interfaces now, but it is a good idea
to keep the newly created SQL server up and running since that makes
testing the interface libraries somewhat simpler.
3.8. Choice of Interfaces: DBI/mSQL, MsqlPerl, and Lite
A frequently quoted saying in the Camel Book (the authorative perl
documentation) states that there is more than one way to achieve a
result when using perl. This, alas, holds true for our model
application, too. Basically there are three ways to access an msql
database via CGI. First of all the question is whether or not perl
shall be used. If we use perl (on which this article focuses) then we
still have the choice between two completely different interface
models. Besides using perl, we can also employ msql's own scripting
language, called Lite, which is reasonably simple and a close clone of
C.
3.8.1. DBI and DBD-mSQL
By the time of this writing, using perl's generic database interface
called DBI is the method of choice. DBI has a few advantages: It
provides unified access control to a number of commercial databases
with a single command set. The actual database in use on a given
system is then contacted through a driver which effectively hides the
pecularities of that database from the programmer. Being such, using
DBI provides for a smooth transition between different databases by
different makers. In one single script it is even possible to contact
several different databases. Please refer to the DBI-FAQ for details.
There is, however, one drawback: The DBI interface is still under
development and shows rapidly galloping version numbers (sometimes
with updates taking place within less than a month). Similarly, the
individual database drivers are also frequently updated and may rely
on specific versions of the database interface. Users making first-
time installations should stick to the version numbers given in this
article since other versions may cause compilation and testing
problems the trouble shooting of which is nothing for the faint-
hearted.
3.8.2. MsqlPerl
MsqlPerl is a library for directly accessing msql from perl scripts.
It bypasses the DBI interface and is fairly compact. Though it works
fine with both versions of msql, its usage is not promoted anymore in
favour of the generalized DBI interface. Nonetheless, in a given
installation it may prove to be the interface of choice since it is
small and easy to install. Notably, it has less version dependencies
than revealed by the interaction of DBI and particular database
drivers.
3.8.3. msql's own scripting language: Lite
Last but not least msql-2 comes with its own scripting language: Lite.
The language is a close relative of C stripped of its oddities with
additional shell-like features (in a way, something like a very
specialized version of perl). Lite is a simple language and is well
documented in the msql-2 manual. The msql-2 package also comes with a
sample application sporting Lite.
We will not describe Lite here because it is well documented but
fairly specific to msql-2, and because it is assumed that the readers
of this article have a basic interest in and a basic understanding of
perl. Nonetheless it is highly recommended to have a closer look at
Lite: it may well be the case that Lite offers the solution of choice
in an exclusive msql-2 environment (implying no other databases are
involved) due to its simplicity and straightforward concept.
3.9. Going the generic way: DBI and DBD-msql
We assume that perl was installed during the system setup or via the
package manager mentioned above. No further details will be given
here. Nonetheless we first test whether our version of perl is up to
date:
# perl -v
perl should respond with the following message:
This is perl, version 5.003 with EMBED
Locally applied patches:
SUIDBUF - Buffer overflow fixes for suidperl security
built under linux at Apr 22 1997 10:04:46
+ two suidperl security patches
Copyright 1987-1996, Larry Wall
[...]
So far, everything is fine. The next step includes installing the perl
libraries for databases in general (DBI), the msql driver (DBD-mSQL)
and CGI. The CGI driver is necessary in any case. The following
archives are necessary:
1. DBI-0.81.tar.gz
2. DBD-mSQL-0.65.tar.gz
3. CGI.pm-2.31.tar.gz (or higher)
A caveat is necessary here for beginners: the test installation
described here works fine using software with exactly these version
numbers, and combinations of other versions failed in one or the other
way. Debugging flawed version combinations is nothing for those who
are not very familiar with the intimate details of the calling
conventions etc. of the interfaces. Sometimes only a method is renamed
while performing the same task, but sometimes the internal structure
changes significantly. So, again, stick with these version numbers if
you want to be on the safe side even if you discover that version
numbers have increased in the meantime. Frequent updates of these
interfaces are the rule rather than the exception, so you should
really anticipate problems when installing other versions than those
indicated here.
It is very important that the database driver for mSQL (DBD-mSQL) is
installed after the generic interface DBI.
We start by creating the directory /usr/local/PerlModules/ as it is
very important to keep the original perl directory tree untouched. We
could also choose a different directory name since the name is
completely uncritical, and unfortunately that is not really mentioned
in the README files of the verious perl modules. Having copied the
above-mentioned archives to /usr/local/PerlModules/ we unpack them
saying
# tar xzvf [archive-file]
for every single of the three archives. Do not forget to supply the
real archive name to tar. The installation process for the three
modules is essentially stardardized; only the screen messages showing
important steps of individual packages are reproduced here.
3.9.1. Installing perl's Database Interface DBI
The database interface must always be installed before installing the
specific database driver. Unpacking the DBI archive creates the
directory /usr/local/PerlModules/DBI-0.81/. Change to that directory.
There are a README file (you should read it) and a perl-specific
makefile. Now issue the command
# perl Makefile.PL
The system should answer with a lengthy message of which the most
important part is shown here::
[...]
MakeMaker (v5.34)
Checking if your kit is complete...
Looks good
NAME => q[DBI]
PREREQ_PM => { }
VERSION_FROM => q[DBI.pm]
clean => { FILES=>q[$(DISTVNAME)/] }
dist => { DIST_DEFAULT=>q[clean distcheck disttest [...]
Using PERL=/usr/bin/perl
WARNING! By default new modules are installed into your 'site_lib'
directories. Since site_lib directories come after the normal library
directories you MUST delete old DBI files and directories from your
Writing Makefile for DBI
This looks good, as the program says, and we can proceed with the next
step:
# make
If no error message occurs (the detailed protocol dumped on screen is
not an error message) we test the newly installed library with the
command
# make test
Watch the output for the following lines (you can always scroll back
with [Shift]-[PgUp]):
[...]
t/basics............ok
t/dbidrv............ok
t/examp.............ok
All tests successful.
[...]
DBI test application $Revision: 1.20 $
Switch: DBI-0.81 Switch by Tim Bunce, 0.81
Available Drivers: ExampleP, NullP, Sponge
ExampleP: testing 2 sets of 5 connections:
Connecting... 1 2 3 4 5
Disconnecting...
Connecting... 1 2 3 4 5
Disconnecting...
Made 10 connections in 0 secs ( 0.00 usr 0.00 sys = 0.00 cpu)
test.pl done
The final step is to install all files in their proper directories.
The following command will take care of it:
# make install
No more duties are left. If for some reason the installation failed
and you want to redo it do not forget to issue
# make realclean
first. This will remove stale leftovers of the previous installation.
You can also remove the files which were installed by copying the
screen contents (shown abbreviated)
Installing /usr/lib/perl5/site_perl/i386-linux/./auto/DBI/DBIXS.h
Installing /usr/lib/perl5/site_perl/i386-linux/./auto/DBI/DBI.so
Installing /usr/lib/perl5/site_perl/i386-linux/./auto/DBI/DBI.bs
[...]
Writing /usr/lib/perl5/site_perl/i386-linux/auto/DBI/.packlist
Appending installation info to /usr/lib/perl5/i386-linux/5.003/perllocal.pod
into a file, replacing every Installing with rm. Provided you named
the file uninstall you can then say
# . uninstall
which will remove the recently installed files.
3.9.2. perl's msql Driver DBD-mSQL
The msql driver can only be installed after a successful installation
of perl's generic database interface.
The basic steps are the same as above; so first go through
# perl Makefile.PL
Here, the system should answer with an urgent warning to read the
accompanying documentation. It will then detect where msql resides,
and asks which version you use:
$MSQL_HOME not defined. Searching for mSQL...
Using mSQL in /usr/local/Hughes
-> Which version of mSQL are you using [1/2]?
State your correct version number. Quite a few lines of text will fol&SHY;
low. Watch for the following ones:
Splendid! Your mSQL daemon is running. We can auto-detect your configuration!
I've auto-detected your configuration to be running on port: 1114
You can now test the driver by saying
# make test
Again, a lengthy output follows. If it ends with
Testing: $cursor->func( '_ListSelectedFields' ). This will fail.
ok: not a SELECT in msqlListSelectedFields!
Re-testing: $dbh->do( 'DROP TABLE testaa' )
ok
*** Testing of DBD::mSQL complete! You appear to be normal! ***
you are on the safe side of life and can install your driver by saying
# make install
You are now ready to go and can skip the next paragraph.
3.10. The MsqlPerl Interface
If you decide to use the exclusive MsqlPerl interface then no generic
database driver is needed, only MsqlPerl-1.15.tar.gz, since, as
mentioned earlier, MsqlPerl provides a direct interface between perl
and the database server without using the DBI interface. Installing
and testing is straightforward.
After saying perl Makefile.PL the make utility can be started. First
you have to answer the question where mSQL resides. If it resides in
/usr/local/Minerva/ the default answer can be confirmed.
Then do a make test. Before doing so you must ensure that you have a
database named test and that you have read and write permissions for
it. This can be done by
# msqladmin create test
3.11. perl's CGI library
Installing perl's CGI part is the simpliest of the three steps.
Execute the following commands in the given order and everything is
done:
# perl Makefile.PL
# make
# make install
Unlike the previous drivers this interface does not have a test option
(# make test) whereas the other modules should be tested in any case.
A subdirectory with CGI example scripts is also created. You can copy
the contents of this directory into /home/http/cgi-bin/ and use the
browser to experiment with the scripts.
3.12. Installation Checklist
We went through the following steps, in this order:
1. Install Linux with networking support
2. Install a http server, e. g. Apache
3. Install a browser, e. g. Arena, lynx or Netscape
4. Install an SQL server, e. g. msql
5. Install a suitable perl SQL interface
6. Install the CGI files
Finally, you can do some clean-up. All source trees for msql and the
perl modules can be safely deleted (however, you should not delete
your archive files!) since the binaries and documentation are now
based in different directories.
4. Running an Example Database
After completing the system installation we can now finally run a
model application. Depending on the version of msql installed and the
perl database interface used, we have to modify the sample programs in
a few points.
First however, the file index.html residing in /home/httpd/html/ must
be modified to allow calling a sample database application. We can
place our database (which we call database.cgi or inventur.cgi here
despite its archive name perl.lst.ck) in /home/httpd/html/test/.
We add one line (of course, depending on your installation choices)
similar to the following to index.html:
______________________________________________________________________
<LI>Test the <A HREF="test/database.cgi">Database, DBI:DBD-mSQL style!</A>
<LI>Test the <A HREF="test/inventur.cgi">Database, MsqlPerl style!</A>
______________________________________________________________________
Usually you should only pick one of these two choices but if you have
both types of database interface installed you can leave both lines
here as they are. You can then compare performance, etc.
4.1. Adapting the sample script for MsqlPerl
Our sample script has to be told to use the MsqlPerl interface. The
modification takes place in several locations. First, near the
beginning of the file, we change the use clause:
______________________________________________________________________
#
# use DBI; # Generisches Datenbank-Interface
use Msql;
______________________________________________________________________
Then, near line 27, the MsqlPerl syntax does not require the
mentioning of a specific driver:
______________________________________________________________________
# $dbh = DBI->connect($host, $database, '', $driver) ||
$dbh = Msql->connect($host, $database) ||
______________________________________________________________________
Then, from line 33 onward throughout the whole script, we have to
change all instances of do against query:
______________________________________________________________________
# $dbh->do("SELECT * FROM hw") || db_init($dbh);
$dbh->query("SELECT * FROM hw") || db_init($dbh);
______________________________________________________________________
Finally, in MsqlPerl speak, line 207 can be commented out:
______________________________________________________________________
# $sth->execute || msg("SQL Error:", $sth->errstr);
______________________________________________________________________
In addition, it may become necessary to swap all errstr calls like the
one in the preceding code fragment against errmsg. This is also
version dependent.
After these modifications, the script should run smoothly.
4.2. Adapting the sample script for msql-2
The SQL syntax was redefined during the development of mslq-2. The
original script will fail to execute the table initialization
statements in lines 45 -- 58. The primary key modifier is no longer
supported by msql-2, and should simply be skipped:
______________________________________________________________________
$dbh->do(<<EOT) || die $dbh->errstr; # Neue Personen-Tabelle
create table person (
# We do not need the 'primary key' modifier anymore in msql-2!
# pn int primary key, # Personalnummer
pn int, # Personalnummer
name char(80), # Nachname, Vorname
raum int # Raumnummer
)
EOT
$dbh->do(<<EOT) || die $dbh->errstr; # Neue Hardware-Tabelle
create table hw (
# We do not need the 'primary key' modifier anymore in msql-2!
# asset int primary key, # Inventurnummer
asset int, # Inventurnummer
name char(80), # Bezeichnung
person int # Besitzer
)
EOT
______________________________________________________________________
Unfortunately, this specific script will then accept new entries with
identical personnel numbers; the msql-1 modifier primary key intends
to prevent exactly this behaviour. The msql-2 documentation shows how
to use the CREATE INDEX clause to create unique entries.
5. Conclusion and Outlook
If you have installed msql-2 on your system then you can have a look
at the sample programs written in Lite, msql-2's own scripting
language.
Either version of msql comes with a basic set of administration tools
which allow the user to create and drop tables (msqladmin) and examine
database structures (relshow).
The second generation msql (i.e. msql-2) has a few more genuinely
useful utilities: msqlimport and msqlexport. These allow the dumping
of flat line data files into and out of the SQL database. They can be
used for loading quantities of existing data d'un coup into existing
tables, or extract flat data from tables, and the user does not have
to deal with writing a single line of perl or SQL or whatever code for
this task.
If you want to write your own perl scripts dealing with databases
you'll find sufficient support in the example files and the extensive
on-line documentation that comes with the DBI module.
Anyway, you are now ready to go and present your data to the users of
your own network, or even the WWW.
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