When using Recital on linux you can integrate your favorite linux shell commands and use then directly inside Recital using the alias command. This can be particularly useful when you ssh into a remote system and run recital. You can then issue linux commands without having to open another terminal session. Several aliased shell commands are predefined in /opt/recital/conf/config.db. You can add others to suit your needs.

By default Recital uses PAM to authenticate users.  It is also possible to tell PAM to use Kerberos.  Simply replace the existing entries in the /etc/pam.d/recital file with the ones below:

auth       sufficient   pam_krb5.so try_first_pass
auth       sufficient   pam_unix.so shadow nullok try_first_pass
account    required     pam_unix.so broken_shadow
account    [default=bad success=ok user_unknown=ignore] pam_krb5.so

The SET RELATION Recital Navigational Data Command can be used to link two (or more) tables based on the master index key of the child table.  With a relation active, as you move through the parent table, the record pointer also moves in the child table, automatically selecting the first related record or moving to the end of file if no related record exists.    

open database southwind
// open child table
use order_details order orderid in 0
// open parent table
use orders order orderid in 0
set relation to orderid into order_details
do while not eof()
    ? orders.orderid, order_details.productid
    skip
enddo

The code above will display the productid from the first related record, but you will often want to display information from all the related records in the child or detail table as in an SQL Left Outer Join.

open database southwind
select orders.orderid, order_details.productid;
from orders left outer join order_details;
on orders.orderid = order_details.orderid

In this case, we can use a second nested DO WHILE loop, for example:

open database southwind
use order_details order orderid in 0
use orders order orderid in 0
set relation to orderid into order_details
do while not eof()
    // Display first or 0 child record
    ? orders.orderid, order_details.productid
    // Display any additional child records
    do while not eof(order_details)
        ? orders.orderid, order_details.productid
        skip in order_details
    enddo
    skip
enddo

Or we can use the SET SKIP command.  The SET SKIP command can be used with DISPLAY, LIST and REPORT and automatically skips through all the related records in the child table.

open database southwind
use order_details order orderid in 0
use orders order orderid in 0
set relation to orderid into order_details
set skip on
set skip to order_details
list orders.orderid, order_details.productid

LIST and DISPLAY offer a number of keyword options to allow you to configure the display output.  REPORT offers full column based report design.

When you start the loadbalancer.org appliance you will see the following:

Default login:
Username: root
Password: loadbalancer

Access to webclient from an external client is:
http://192.168.1.129:9080
http://192.168.1.129:9443

You can access the web administrator using the IP and ports described onscreen.

For the sri lanka porject we are looking for performance and the network diagram indicates we are happy to have the cluster on the same subnet as the rest of the network.

Direct routing is the fasted performance possible, it has the advantage over NAT that the Loadbalancer does not become a bottleneck for incoming and outgoing packets. With DR the loadbalancer simply examines incoming packets and the servers to route the packets directly back to the requesting user.

The web interfaceis the only way to fully configure the loadbalancer vm. The console tool lbwizard will get it initiallised and any further configurations can then be done via the webinterface.

Using lbwizard for the Sri lanka configuration follow these steps.

On the first Loadbalancer:

//Start

Is this unit part for a HA Pair?
YES

Have you already setup the Slave?
NO

Is this a one-armed configuration?
YES

Enter the IP Address for the interface eth0?
Enter IP address you wish to be assigned to the SLAVE loadbalancer.

Enter the netmask for interface eth0?
Enter netmask for the subnet.

Enter the Floating IP adrress?
Enter the IP address that will be IP assosiacted the the HA-pair of loadbalancers.

//Finish

On the 2nd loadbalancer VM, run the lbwizard.

//Start

Is this unit part of an HA-Pair?
YES

Have you already set up the Slave?
YES

What is the slave units UP address?
Enter the IP which you entered when configuring the other loadbalancer VM.

Is this a one-armed configuration?
YES

Enter the IP Address for the interface eth0?
Enter the IP that will be assigned to the MASTER loadbalancer

Enter the netmask for interface eth0?
Enter the subnet netmask.

Enter the Floating IP address?
Enter the IP address that will be IP assosiacted the the HA-pair of loadbalancers.

Enter the address of the default gateway?
Enter the deafult gateway for the subnet.

Enter the IP of the nameserver?
Enter the dns server.

Enter the port for the first Virtual server?
Enter 22 for ssh

Enter the IP address of the first real server?
Enter the real IP of the first appserver

//Finish

Now this is complete we need to go to the web admin interface to configure the 2nd Real Server. As the lbwizard program will only allow you to configure 1 real server.

Now login to the web admin using the default password:

username: loadbalancer
password: loadbalancer

Note: Connect to the IP you have now set for your master loadbalancer

Goto the edit configuration tab

Now click add a real server:

Enter a label
IP address of the server plus the port of the service i.e. 192.168.1.125:22


Edit Configuration -> Virtual Servers

persistancte -> NO

Scheduler-> LC
LC - Least-Connection: assign more jobs to real servers with
fewer active jobs.

Service to check -> custom1

Check port -> 22

Forwarding Method -> DR

Feedback Method -> Agent

Arp Problem when using DR

Every real server must be configured to respond to the VIP address as well as the RIP
address.

You can use iptables (netfilter) on the real server to re-direct incoming packets destined for the virtual
server IP address.

This is a simple case of adding the following command to your start up script (rc.local):

//replace 10.0.0.21 with the Virtual Server IP
iptables -t nat -A PREROUTING -p tcp -d 10.0.0.21 -j REDIRECT

chkconfig iptables on