In this article Barry Mavin explains step by step how to setup a Linux HA (High Availability) cluster for the running of Recital applications on Redhat/Centos 5.3 although the general configuration should work for other linux versions with a few minor changes.
$hdiutil create /tmp/tmp.dmg -ov -volname "RecitalInstall" -fs HFS+ -srcfolder "/tmp/macosxdist/"
$hdiutil convert /tmp/tmp.dmg -format UDZO -o RecitalInstall.dmg
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
Recital 10 Express Edition Linux x86 Free Download.
Recital 10 introduces the free single-user developer edition called Recital Express that can be used to develop and test multi-user Recital, Recital Server and Recital Web applications. Once the applications are ready for deployment a commercial license must be purchased. Recital Express, Recital Server Express and Recital Web Express can be used unlicensed for non-commercial purposes only.What does this download include:
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Recital 10 A powerful scripting language with an embedded database used for developing desktop database applications on Linux and Unix. Recital has a high degree of compatibility with Microsoft FoxPRO enhanced with many additional enterprise class extensions. |
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Recital 10 Web A server-side scripting language with an embedded database for creating web 2.0 applications. Includes plugins for apache and IIS. Coming soon! Recital Web Framework, a comprehensive OO framework built on YUI for building RIA (Rich Internet Applications) in Recital Web. |
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Recital 10 Server A cross-platform SQL database and application server which includes client drivers for ODBC, JDBC and .NET enabling Recital data to be accessed client/server from Windows, Linux and Mac. |
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Recital 10 Replication A comprehensive replication product that addresses urgent data movement and synchronization needs to help support disaster recovery and business continuity for Recital applications. |
Recital 10 Quick Start:
Graphical Installation
Note: The installation must be run as root. For systems with a hidden root account, please use ’Run as Root’.
- Download the distribution file into a temporary directory
- Check that the distribution file has the execute permission set
- Run the distribution file
- Follow the on screen instructions:
- License agreement
- Select components
- Installation directory and shortcuts
- Linking to /usr/bin
- ODBC Installation type (Recital Server / Recital Client Drivers)
- Java Virtual Machine selection (Recital Server / Recital Client Drivers)
- TomCat Installation type (Recital Server / Recital Client Drivers)
- Apache Firecat Plugin Installation (Recital Web Developer)
- Replication Service Type (Recital Replication Server)
- Install license file
Text Installation
Note: The installation must be run as root. For systems with a hidden root account, please precede commands with ’sudo’.
- Download the distribution file into a temporary directory
- Check that the distribution file has the execute permission set
- Run the distribution file
- Follow the on screen instructions:
- License agreement
- Select components
- Installation directory and shortcuts
- Linking to /usr/bin
- ODBC Installation type (Recital Server / Recital Client Drivers)
- Java Virtual Machine selection (Recital Server / Recital Client Drivers)
- TomCat Installation type (Recital Server / Recital Client Drivers)
- Apache Firecat Plugin Installation (Recital Web Developer)
- Replication Service Type (Recital Replication Server)
- Install license file
USE accounts INDEX on account_no TAG outstanding FOR balance > 0 EXPLAIN SELECT * FROM accounts WHERE balance > 0 Optimized using for condition on tag 'OUTSTANDING'
lslk lists information about locks held on files with local inodes on systems running linux.
Install it with:
yum install lslk
The best way to learn Recital is to build some applications. The developers of Recital have written a book "Recital Essentials" which you can read here.
Usually, you do not need to setup an email server under Linux. Most GUI email clients support Gmail POP3 and IMAP configurations. But, how do you send mail via the standard /usr/bin/mail user agents in a shell script? Programs such as sendmail / postfix / exim can be configured as a gmail smarthost but they are largely overkill for this use. The ssmtp program is a neat utility that does just that for you via gmail.
In this article Barry Mavin explains step by step how to setup a Linux HA (High Availability) cluster for the running of Recital applications on Redhat/Centos 5.3 although the general configuration should work for other linux versions with a few minor changes.
In this article Barry Mavin, CEO and Chief Software Architect for Recital, details Working with Stored Procedures in the Recital Database Server.
Overview
Stored procedures and user-defined functions are collections of SQL statements and optional control-of-flow statements written in the Recital 4GL (compatible with VFP) stored under a name and saved in a Database. Both stored procedures and user-defined functions are just-in-time compiled by the Recital database engine. Using the Database Administrator in Recital Enterprise Studio, you can easily create, view, modify, and test Stored Procedures, Triggers, and user-defined functions
Creating and Editing Stored Procedures
To create a new Stored Procedure, right-click the Procedures node in the Databases tree of the Project Explorer and choose Create. To modify an existing stored procedure select the Stored Procedure in the Databases Tree in the Project Explorer by double-clicking on it or selecting Modify from the context menu . By convertion we recommend that you name your Stored Procedures beginning with "sp_xxx_", user-defined functions with "f_xxx_", and Triggers with "dt_xxx_", where xxx is the name of the table that they are associated with.
Testing the Procedure
To test run the Stored Procedure, select the Stored Procedure in the Databases Tree in the Project Explorer by double-clicking on it. Once the Database Administrator is displayed, click the Run button to run the procedure.
Getting return values
Example Stored Procedure called "sp_myproc":
parameter arg1, arg2 return arg1 + arg2
Example calling the Stored Procedure from C# .NET:
////////////////////////////////////////////////////////////////////////
// include the references below
using System.Data;
using Recital.Data;
////////////////////////////////////////////////////////////////////////
// sample code to call a Stored Procedure that adds to numeric values together
public int CallStoredProcedure()
{
RecitalConnection conn = new
RecitalConnection("Data Source=localhost;Database=southwind;uid=?;pwd=?");
RecitalCommand cmd = new RecitalCommand();
cmd.Connection = conn;
cmd.CommandText = "sp_myproc(@arg1, @arg2)";
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters["@arg1"].Value = 10;
cmd.Parameters["@arg2"].Value = 20;
conn.Open();
cmd.ExecuteNonQuery();
int result = (int)(cmd.Parameters["retvalue"].Value); // get the return value from the sp
conn.Close();
return result;
}
Writing Stored Procedures that return a Resultset
If you want to write a Stored Procedure that returns a ResultSet, you use the SETRESULTSET() function of the 4GL. Using the Universal .NET Data Provider, you can then execute the 4GL Stored Procedure and return the ResultSet to the client application for processing. ResultSets that are returned from Stored Procedures are read-only.
Example Stored Procedure called "sp_myproc":
parameter query
select * from customers &query into cursor "mydata"
return setresultset("mydata")
Example calling the Stored Procedure from C# .NET:
////////////////////////////////////////////////////////////////////////
// include the references below
using System.Data;
using Recital.Data;
////////////////////////////////////////////////////////////////////////
// sample code to call a stored procedure that returns a ResultSet
public void CallStoredProcedure()
{
RecitalConnection conn = new
RecitalConnection("Data Source=localhost;Database=southwind;uid=?;pwd=?");
RecitalCommand cmd = new RecitalCommand();
cmd.Connection = conn;
cmd.CommandText = "sp_myproc(@query)";
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters["@query"].Value = "where not deleted()";
conn.Open();
RecitalDataReader dreader = cmd.ExecuteReader();
int sqlcnt = (int)(cmd.Parameters["sqlcnt"].Value); // returns number of affected rows
while (dreader.Read())
{
// read and process the data
}
dreader.Close();
conn.Close();
}