-Last updated: 02/10/2001 +Last updated: 02/12/2001
This file describes issues associated with LON-CAPA and a SQL database.
-
I am going to begin documentation by inserting what notes I have into this file. I will be subsequently rearranging @@ -39,7 +39,7 @@ current status of everything is that it been minimally tested, but things need to be cleaned up and checked again!
-Right now, a lot of "feasibility" work has been done. Recipes for manual installation and configuration have @@ -70,7 +70,7 @@ to the point of getting this SQL softwar however there may be more optimal approaches than currently exist.
-LON-CAPA is meant to distribute A LOT of educational content to A LOT of people. It is ineffective to directly rely on contents @@ -131,7 +131,7 @@ THE SOLUTION: processes (lonsql's) handle the MySQL database manipulations.
-Installation of the LON-CAPA SQL database normally occurs by default when using the LON-CAPA installation CD @@ -160,7 +160,7 @@ from source or pre-compiled file listing actual MySQL functionality on the system
-The following set of tarballs was found to work together properly on a LON-CAPA RedHat 6.2 system: @@ -174,13 +174,13 @@ properly on a LON-CAPA RedHat 6.2 system Installation was simply a matter of following the instructions and typing the several "make" commands for each
-Not yet developed. This will be part of an interface present on LON-CAPA systems that can be launched by entering the command /usr/sbin/loncapaconfig.
-This is not complete.
@@ -215,124 +215,9 @@ FLUSH PRIVILEGES; Copy support-files/mysql.server to the right place on the system (/etc/rc.d/...). --Not yet documented or formalized. -
--
- --
-start the mysql daemon as /usr/local/bin/safe_mysqld &
-Login as root: mysql -u root -p mysql
-enter the password as newmysql
-add the user www: grant all priveleges on *.* to www@localhost identified by 'newmysql' with grant option;
-
-INSERT INTO user (Host, User, Password)
-VALUES ('localhost','www',password('newmysql'));
-
-GRANT ALL PRIVILEGES ON *.* TO www@localhost;
-
-FLUSH PRIVILEGES;
-
-Here the user www has the right to grant privileges to other users.
-This can be changed if required with a simple update command on the grant tables
-
-
-/home/httpd/perl/perlsql/lonsql
-/usr/local/mysql/fakeclient
-
-
--
-This is the output from scripts/mysql_install_db... -still some todo things (like support-files/mysql.server) - -Creating db table -Creating host table -Creating user table -Creating func table -Creating tables_priv table -Creating columns_priv table - -To start mysqld at boot time you have to copy support-files/mysql.server -to the right place for your system - -PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER ! -This is done with: -/usr/local/bin/mysqladmin -u root password 'new-password' -See the manual for more instructions. - -Please report any problems with the /usr/local/bin/mysqlbug script! - -The latest information about MySQL is available on the web at http://www.mysql.com -Support MySQL by buying support/licenses at http://www.tcx.se/license.htmy. -- -
+The Perl API
-August, 29 2000; Scott Harrison; LON-CAPA
-
-These are notes related to a Perl interface and MySQL server installation
-on Redhat 6.1 and 6.2 boxes. (Guy Albertelli and Harsha Jagasia
-contributed significantly to this.)
-
-********************
-* MySQL COMPONENTS *
-********************
-
-There are three components to an effective MySQL installation for the
-LON-CAPA system.
-
-Perl::DBI module- the API "front-end"...
- database interface module for organizing generic
- database commands which are independent of specific
- database implementation (such as MySQL, mSQL, Postgres, etc).
-
-Perl::MySQL module- the API "mid-section"...
- the module to directly interface with the actual
- MySQL database engine
-
-MySQL database engine- the "back-end"...
- the binary installation (compiled either from source
- or pre-compiled file listings) which provides the
- actual MySQL functionality on the system
-
-RedHat Installation-
-
-Initially done from source:
-DBI-1.13.tar.gz Msql-Mysql-modules-1.2209.tar.gz mysql-3.22.32.tar.gz
-
-I am now using pre-compiled file listings.
-
-There were problems with using the RedHat packages since the three
-different RedHat packages were somewhat noncompatible with each other
-in terms of expected file locations. (The Debian linux distribution,
-on the other hand, has a working set of these packages).
-
-Regardless of how we install these three components, there still remain
-certain things which need to happen for the configuration.
-
-*****************
-* CONFIGURATION *
-*****************
-
-(Note: SOMEPASSWORD is actually set to another text string on the current
-LON-CAPA systems.)
-
-Configuration is needed to generate the necessary functionality for the
-MySQL system with LON-CAPA.
-
-The functionality needed can be understood from this example line
-of perl code from "lonsql".
-
$dbh = DBI->connect( "DBI:mysql:loncapa",
"www",
"SOMEPASSWORD",
@@ -395,56 +280,28 @@ FLUSH PRIVILEGES;
** ABILITY for LON-CAPA machines to communicate with SQL databases on
other LON-CAPA machines
-This is a little more intricate than might first be expected (and I probably
-won't do a perfect job reciting everything in this short synopsis). Because
-LON-CAPA machines will likely be handling many SQL requests at a time,
-there were some problems with current MySQL capabilities.
-
-PROBLEM SITUATION:
-
- If Server A wants data from Server B, Server A uses a lonc process to
- send a database command to a Server B lond process.
- lonc= loncapa client process A-lonc= a lonc process on Server A
- lond= loncapa daemon process
-
- database command
- A-lonc --------TCP/IP----------------> B-lond
-
- The problem emerges that A-lonc and B-lond are kept waiting for the
- MySQL server to "do its stuff", or in other words, perform the conceivably
- sophisticated, data-intensive, time-sucking database transaction. By tying
- up a lonc and lond process, this significantly cripples the capabilities
- of LON-CAPA servers.
-
- While commercial databases have a variety of features that ATTEMPT to
- deal with this, freeware databases are still experimenting and exploring
- with different schemes with varying degrees of performance stability.
-
-THE SOLUTION:
-
- A separate daemon process was created that B-lond works with to
- handle database requests. This daemon process is called "lonsql".
-
- So,
- database command
- A-lonc ---------TCP/IP-----------------> B-lond =====> B-lonsql
- <---------------------------------/ |
- "ok, I'll get back to you..." |
- |
- /
- A-lond <------------------------------- B-lonc <======
- "Guess what? I have the result!"
-
- Of course, depending on success or failure, the messages may vary,
- but the principle remains the same where a separate pool of children
- processes (lonsql's) handle the MySQL database manipulations.
+An up-to-date lond and lonsql.
+
+
++
+** TEST the database connection with my current tester.pl code +which mimics what command will eventually be sent through lonc. +$reply=reply( + "querysend:SELECT * FROM general_information WHERE Id='AAAAA'",$lonID); ++ +
Here are excerpts of code which implement the above handling: - -**LONSQL - +
++
+**LONSQL
A subroutine from "lonsql" which establishes a child process for handling
-database interactions.
+database interactions.
sub make_new_child {
my $pid;
@@ -536,14 +393,19 @@ sub make_new_child {
exit;
}
}
-
-** LOND enabling of MySQL requestsw
-
- This code is part of every lond child process in the way that it parses command request syntax
- sent to it from lonc processes. querysend corresponds to B-lonc sending the result of the query.
- queryreply corresponds to B-lond indicating that it has received the request and will start the
- database transaction (it returns "ok" to A-lonc ($client)).
-
+
+
+** LOND enabling of MySQL requests
+
+This code is part of every lond child process in the
+way that it parses command request syntax sent to it
+from lonc processes. Based on the diagram above, querysend
+corresponds to B-lonc sending the result of the query.
+queryreply corresponds to B-lond indicating that it has
+received the request and will start the database transaction
+(it returns "ok" to
+A-lonc ($client)).
+
# ------------------------------------------------------------------- querysend
} elsif ($userinput =~ /^querysend/) {
my ($cmd,$query)=split(/:/,$userinput);
@@ -563,14 +425,8 @@ sub make_new_child {
print $client "error:$!\n";
}
-
-
-** TEST the database connection with my current tester.pl code which mimics what command will eventually be
- sent through lonc.
-
-$reply=reply(
- "querysend:SELECT * FROM general_information WHERE Id='AAAAA'",$lonID);
+