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

This article discusses the features in Recital that allow data to be imported and exported between platforms in Microsoft® ADO XML Format.

Overview

Extensible Markup Language, XML, is widely regarded as a lingua franca for the interchange of data. XML's text-based, platform-independent format and its integration of data and the schema to define and describe that data, make it the ideal import/export medium. Recital software provides the functionality to output the data from Recital - and other supported table formats such as FoxPro and FoxBASE - into XML file format and to import XML data into those tables' formats. Such import/export operations provide the means to exchange data with third-party applications and can also facilitate the transfer of data between Recital installations on binary-incompatible platforms.

The features examined in this article are available in Recital Terminal Developer and in the Recital Mirage and Recital Database Servers on all Recital supported platforms. Both the Recital/4GL and Recital/SQL provide XML import and export capabilities. The XML files discussed are in Microsoft® ADO XML format.

Microsoft® ActiveX® Data Objects XML Format

The ADO XML format is primarily designed for ADO Recordset persistence and ADO XML files created by Recital can be used in this way and loaded directly into ADO Recordsets. The format can, though also be used for more generic data transfer. An ADO XML file is self-contained, consisting of two sections: a schema section followed by a data section. The schema conforms to the W3C XML-Data specification and defines the data structure.
For additional information on the Microsoft® ActiveX® Data Objects XML Format, please see Appendix 1.

NOTE: The Recital XMLFORMAT setting should always be in its default setting of ADO for ADO XML Format operations.

set xmlformat to ADO

SQL

Recital/SQL offers the ability to export data into XML files using the SELECT and FETCH statements and import from XML using the CREATE TABLE and INSERT statements.

SQL: Exporting

The SELECT...SAVE AS XML statement allows the complete result set from a SELECT statement to be saved as an XML file. This could be a complete table:

open database southwind
  SELECT * from orders SAVE AS XML orders.xml

or a more complex multi-table query:

open database southwind
SELECT orders.orderid, orders.customerid,;
    employees.employeeid, employees.lastname, employees.firstname,;
    orders.orderdate, orders.freight, orders.requireddate,;
    orders.shippeddate, orders.shipvia, orders.shipname,;
    orders.shipaddress, orders.shipcity,;
    orders.shipregion, orders.shippostalcode, orders.shipcountry,;
    customers.companyname, customers.address, customers.city,;
    customers.region, customers.postalcode, customers.country; 
    FROM orders INNER JOIN customers;
    ON customers.customerid = orders.customerid,;
    orders INNER JOIN employees;
    ON orders.employeeid = employees.employeeid;
    SAVE AS XML orderinfo

The resulting XML file can then be further processed within the same or a different Recital environment or transferred to a third party product.

<x-ml xmlns:z="#RowsetSchema" xmlns:rs="urn:schemas-microsoft-com:rowset"
 xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:s="uuid:BDC6E3F0-6DA3-11d1-A2A3-
00AA00C14882">
 <s:schema id="RowsetSchema">
  <s:elementtype rs:updatable="true" content="eltOnly" name="row">
   <s:attributetype rs:basecolumn="orderid" rs:basetable="orders.dbf" rs:write="true"
 rs:nullable="true" rs:number="1" name="orderid">
   <s:datatype rs:fixedlength="true" rs:precision="14" rs:scale="0" dt:maxlength="10"
 rs:dbtype="numeric" dt:type="number">
   </s:datatype></s:attributetype>
   <s:attributetype rs:basecolumn="customerid" rs:basetable="orders.dbf" rs:write="true"
 rs:nullable="true" rs:number="2" name="customerid">
   <s:datatype rs:fixedlength="true" dt:maxlength="5" rs:dbtype="str" dt:type="string">
   </s:datatype></s:attributetype>
   <s:attributetype rs:basecolumn="employeeid" rs:basetable="orders.dbf" rs:write="true"
 rs:nullable="false" rs:number="3" name="employeeid">
   <s:datatype rs:fixedlength="true" rs:precision="20" rs:scale="0" dt:maxlength="10"
 rs:dbtype="numeric" dt:type="number">
   </s:datatype></s:attributetype>
   <s:attributetype rs:basecolumn="lastname" rs:basetable="orders.dbf" rs:write="true"
 rs:nullable="false" rs:number="4" name="lastname">
   <s:datatype rs:fixedlength="true" dt:maxlength="20" rs:dbtype="str" dt:type="string">
   </s:datatype></s:attributetype>
   <s:attributetype rs:basecolumn="firstname" rs:basetable="orders.dbf" rs:write="true"
 rs:nullable="false" rs:number="5" name="firstname">
   <s:datatype rs:fixedlength="true" dt:maxlength="10" rs:dbtype="str" dt:type="string">
   </s:datatype></s:attributetype>
   <s:attributetype rs:basecolumn="orderdate" rs:basetable="orders.dbf" rs:write="true"
 rs:nullable="true" rs:number="6" name="orderdate">
   <s:datatype rs:fixedlength="true" dt:maxlength="10" rs:dbtype="Date" dt:type="Date">
   </s:datatype></s:attributetype>
   <s:attributetype name="freight" ...

Click image to display full size

Fig 1: Microsoft® Office Excel 2003: orderinfo.xml.

For data accessed through a Recital Database Gateway, such as Oracle, MySQL or PostgreSQL, the FETCH command can be used to save a cursor results set into an XML file:

// Connect to MySQL Database 'mydata' via Recital Database Gateway
nStatHand=SQLSTRINGCONNECT("mys@mysql1:user1/pass1-mydata",.T.)
if nStatHand < 1
  dialog box [Could not connect]
else
  DECLARE cursor1 CURSOR FOR;
      SELECT account_no, last_name, first_name FROM example
  OPEN cursor1
  FETCH cursor1 INTO XML exa1.xml
  SQLDISCONNECT(nStatHand)
endif

SQL: Importing

The CREATE TABLE statement allows a new table to be created based on the structure defined in an XML file. The data from the XML file can optionally be loaded into this new table if the LOAD keyword is included. For example, a new 'orderinfo' table can be created and populated with data from the orderinfo.xml file created by the SELECT...SAVE AS XML statement shown earlier:

open database southwind
SELECT orders.orderid, orders.customerid,;
    employees.employeeid, employees.lastname, employees.firstname,;
    orders.orderdate, orders.freight, orders.requireddate,;
    orders.shippeddate, orders.shipvia, orders.shipname,;
    orders.shipaddress, orders.shipcity,;
    orders.shipregion, orders.shippostalcode, orders.shipcountry,;
    customers.companyname, customers.address, customers.city,;
    customers.region, customers.postalcode, customers.country; 
    FROM orders INNER JOIN customers;
    ON customers.customerid = orders.customerid,;
    orders INNER JOIN employees;
    ON orders.employeeid = employees.employeeid;
    SAVE AS XML orderinfo

CREATE TABLE orderinfo FROM XML orderinfo LOAD

The INSERT statement can be used to load data when the table structure already exists. Taking our earlier orderinfo.xml file again, the data can be loaded using INSERT:

open database southwind;
SELECT orders.orderid, orders.customerid,;
    employees.employeeid, employees.lastname, employees.firstname,;
    orders.orderdate, orders.freight, orders.requireddate,;
    orders.shippeddate, orders.shipvia, orders.shipname,;
    orders.shipaddress, orders.shipcity,;;
    orders.shipregion, orders.shippostalcode, orders.shipcountry,;
    customers.companyname, customers.address, customers.city,;
    customers.region, customers.postalcode, customers.country; 
    FROM orders INNER JOIN customers;
    ON customers.customerid = orders.customerid,;
    orders INNER JOIN employees;
    ON orders.employeeid = employees.employeeid;
    SAVE AS XML orderinfo
CREATE TABLE orderinfo FROM XML orderinfo

INSERT INTO orderinfo FROM XML orderinfo

The examples above show the export and import in a single piece of code. To transfer data between binary-incompatible platforms, the export phase using SELECT...SAVE AS XML would be carried out on the source platform, the resulting XML file would be transferred to the target platform, then the import phase using CREATE TABLE...LOAD or CREATE TABLE + INSERT would be run on the target platform.

Recital/4GL

The Recital/4GL offers the ability to export data into XML files using the COPY TO ... TYPE XML command and import from XML using the XMLFIRST() and XMLNEXT() functions.

Recital/4GL: Exporting

The COPY TO command can be used to export data from Recital and other natively supported tables out to a wide range of formats. This includes exporting to an XML file. The '.xml' file extension is added automatically. The COPY TO command can be used to export an entire table:

open database southwind
use orders
copy to orders type xml

or, using the FIELDS clause and the FOR or WHILE clauses, restrict the field list and export only those records which match a particular condition:

open database southwind
use orders
copy to orders type xml fields orderid for year(orderdate) = 1996

Only the orderid field from those records which match the condition is exported:

<x-ml xmlns:z="#RowsetSchema" xmlns:rs="urn:schemas-microsoft-com:rowset"
 xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:s="uuid:BDC6E3F0-6DA3-11d1-A2A3-
00AA00C14882">
 <s:schema id="RowsetSchema">
  <s:elementtype rs:updatable="true" content="eltOnly" name="row">
   <s:attributetype rs:basecolumn="ORDERID" rs:basetable="ORDERS" rs:write="true" rs:nullable="true"
 rs:number="1" name="ORDERID">
   <s:datatype rs:fixedlength="true" rs:precision="10" rs:scale="0" dt:maxlength="10"
 rs:dbtype="numeric" dt:type="number">
   </s:datatype></s:attributetype>
  </s:elementtype>
 </s:schema>
 <rs:data>
 <z:row orderid="10248">
 <z:row orderid="10249">
 <z:row orderid="10250">
 <z:row ...

Recital/4GL: Importing

Data from an XML file can be extracted one record at a time using the XMLFIRST() and XMLNEXT() functions. XMLFIRST() reads the first record from an XML file and loads information from the file into a series of memory variables and arrays. The record data is loaded into a one-dimensional array which is created automatically. Each element in the array contains the data for its corresponding field in string format. The field names are loaded into another automatically-created array. The XMLNEXT() function works in a similar way to deal with all the subsequent records in the XML file. The XMLCOUNT() function can be used, as in the example below, to determine how many data records the XML file has.

The Recital/4GL includes a vast range of functions for manipulation and conversion of arrays and their individual elements. In the example program below, the XMLFIRST() and XMLNEXT() functions are used to sequentially extract each record from an XML file, whose name is passed to the program as a parameter. Once loaded into an array, the data is converted to the correct Recital data type then appended into a table. The table name is also passed as a parameter.

procedure replaceit
  append blank
  for i = 1 to numfields
    if type(field(i)) = "N"
      replace &(field(i)) with val(data[&i])
    elseif type(field(i)) = "D"
      replace &(field(i)) with stod(data[&i])
    elseif type(field(i)) = "T"
      replace &(field(i)) with ctot(data[&i])
    elseif type(field(i)) = "L"
      replace &(field(i)) with iif(data[&i]="T",.T.,.F.)
    elseif type(field(i)) = "Y"
      replace &(field(i)) with val(data[&i])
    else
      replace &(field(i)) with data[&i]
    endif
  next
return
 
procedure starthere                    
  parameters cTable, cFile
  numfields=xmlfirst(cFile,targ,trans,where,fldnames,data)
  if numfields < 1
    dialog box [No records in XML file]
  else
    use &cTable
    replaceit()
  endif
  numrecs = xmlcount(cFile)
  if numrecs > 1
    numleft = numrecs -1
    for i = 1 to numleft
      xmlnext(trans,where,fldnames,data)
      replaceit()
    next
  endif
return

Alternative Import/Export Methods

Other features exist in Recital to facilitate the import and export of data:

RDDs

The RDDs, Replaceable Database Drivers, are available on Windows, Linux and all supported 32-bit UNIX platforms. They allow for the use and creation of database tables and indexes in FoxPro, dBase and Clipper formats. The file format is the same across all the platforms that support the RDDs, allowing the tables and indexes to be transferred as required. The formats are also supported by a wide range of third-party products as well as their originating database systems. For more information on the RDDs, please see the online documentation on Xbase migration and the SET FILETYPE command.

BUILD/INSTALL

These are Recital/4GL commands for the export (BUILD) and import (INSTALL) of Recital tables and their associated memo, dictionary and multiple index files in ASCII format to allow them to be transferred across binary incompatible platforms. For more information, please see the online documentation on Recital/4GL commands.

COPY Commands

The COPY TO, COPY STRUCTURE, COPY STRUCTURE EXTENDED and CREATE FROM commands can all be used to enable data to be transferred between different formats and different platforms. For more information, please see the online documentation on Recital/4GL commands.

Appendix 1: Microsoft® ActiveX® Data Objects XML Format

For detailed information on the Microsoft® ActiveX® Data Objects XML Format, please consult the following Microsoft documentation: