In this article Barry Mavin, CEO and Chief Software Architect for Recital provides details on how to use the Recital Universal .NET Data Provider with the Recital Database Server.
Overview
A data provider in the .NET Framework serves as a bridge between an application and a data source. A data provider is used to retrieve data from a data source and to reconcile changes to that data back to the data source.
Each .NET Framework data provider has a DataAdapter object: the .NET Framework Data Provider for OLE DB is the OleDbDataAdapter object, the .NET Framework Data Provider for SQL Server is the SqlDataAdapter object, the .NET Framework Data Provider for ODBC is the OdbcDataAdapter object, and the .NET Framework Data Provider for the Recital Database Server is the RecitalDataAdapter object.
The Recital Universal .NET Data Provider can access any data sources supported by the Recital Database Server. It is not restricted to only access Recital data. It can be used to access server-side ODBC, JDBC and OLE DB data sources also.
Core classes of the Data Provider
The Connection, Command, DataReader, and DataAdapter objects represent the core elements of the .NET Framework data provider model. The Recital Universal .NET Data Provider is plug compatible with the .NET Framework Data Provider for SQL Server. All SQL Server classes are prefixed with "Sql" e.g. SqlDataAdaptor. To use the Recital Universal Data Adaptor, simply change the "Sql" prefix to "Recital" e.g. RecitalDataAdaptor.
The following table describes these objects.
| Object | Description |
|---|---|
| RecitalConnection | Establishes a connection to a specific data source. |
| RecitalCommand | Executes a command against a data source. |
| RecitalDataReader | Reads a forward-only, read-only stream of data from a data source. |
| RecitalDataAdapter | Populates a DataSet and resolves updates with the data source. |
Along with the core classes listed in the preceding table, a .NET Framework data provider also contains the classes listed in the following table.
| Object | Description |
|---|---|
| RecitalTransaction | Enables you to enlist commands in transactions at the data source. |
| RecitalCommandBuilder | A helper object that will automatically generate command properties of a DataAdapter or will derive parameter information from a stored procedure and populate the Parameters collection of a Command object. |
| RecitalParameter | Defines input, output, and return value parameters for commands and stored procedures. |
The Recital Universal .NET Data Provider provides connectivity to the Recital Database Server running on any supported platform (Windows, Linux, Unix, OpenVMS) using the RecitalConnection object. The Recital Universal .NET Data Provider supports a connection string format that is similar to the SQL Server connection string format.
The basic format of a connection string consists of a series of keyword/value pairs separated by semicolons. The equal sign (=) connects each keyword and its value.
The following table lists the valid names for keyword values within the ConnectionString property of the RecitalConnection class.
| Name | Default | Description |
|---|---|---|
| Data Source -or- Server -or- Servername -or- Nodename |
The name or network address of the instance of the Recital Database Server which to connect to. | |
| Directory | The target directory on the remote server where data to be accessed resides. This is ignored when a Database is specified. | |
| Encrypt -or- Encryption |
false | When true, DES3 encryption is used for all data sent between the client and server. |
| Initial Catalog -or- Database |
The name of the database on the remote server. | |
| Password -or- Pwd |
The password used to authenticate access to the remote server. | |
| User ID -or- uid -or- User -or- Username |
The user name used to authenticate access to the remote server. | |
| Connection Pooling -or- Pool |
false | Enable connection pooling to the server. This provides for one connection to be shared. |
| Logging | false | Provides for the ability to log all server requests for debugging purposes |
| Rowid | true | When Rowid is true (the default) a column will be post-fixed to each SELECT query that is a unique row identifier. This is used to provide optimised UPDATE and DELETE operations. If you use the RecitalSqlGrid, RecitalSqlForm, or RecitalSqlGridForm components then this column is not visible but is used to handle updates to the underlying data source. |
| Logfile | The name of the logfile for logging | |
| Gateway |
Opens an SQL gateway(Connection) to a foreign SQL data source on the remote server.
The gateway can be specified in several formats: |
Populating a DataSet from a DataAdaptor
The ADO.NET DataSet is a memory-resident representation of data that provides a consistent relational programming model independent of the data source. The DataSet represents a complete set of data including tables, constraints, and relationships among the tables. Because the DataSet is independent of the data source, a DataSet can include data local to the application, as well as data from multiple data sources. Interaction with existing data sources is controlled through the DataAdapter.
A DataAdapter is used to retrieve data from a data source and populate tables within a DataSet. The DataAdapter also resolves changes made to the DataSet back to the data source. The DataAdapter uses the Connection object of the .NET Framework data provider to connect to a data source and Command objects to retrieve data from and resolve changes to the data source.
The SelectCommand property of the DataAdapter is a Command object that retrieves data from the data source. The InsertCommand, UpdateCommand, and DeleteCommand properties of the DataAdapter are Command objects that manage updates to the data in the data source according to modifications made to the data in the DataSet.
The Fill method of the DataAdapter is used to populate a DataSet with the results of the SelectCommand of the DataAdapter. Fill takes as its arguments a DataSet to be populated, and a DataTable object, or the name of the DataTable to be filled with the rows returned from the SelectCommand.
The Fill method uses the DataReader object implicitly to return the column names and types used to create the tables in the DataSet, as well as the data to populate the rows of the tables in the DataSet. Tables and columns are only created if they do not already exist; otherwise Fill uses the existing DataSet schema.
Examples in C#:
////////////////////////////////////////////////////////////////////////
// include the references below
using System.Data;
using Recital.Data;
////////////////////////////////////////////////////////////////////////
// The following code example creates an instance of a DataAdapter that
// uses a Connection to the Recital Database Server Southwind database
// and populates a DataTable in a DataSet with the list of customers.
// The SQL statement and Connection arguments passed to the DataAdapter
// constructor are used to create the SelectCommand property of the DataAdapter.
public DataSet SelectCustomers()
{
RecitalConnection swindConn = new
RecitalConnection("Data Source=localhost;Initial Catalog=southwind");
RecitalCommand selectCMD = new
RecitalCommand("SELECT CustomerID, CompanyName FROM Customers", swindConn);
selectCMD.CommandTimeout = 30;
RecitalDataAdapter custDA = new RecitalDataAdapter();
custDA.SelectCommand = selectCMD;
swindConn.Open();
DataSet custDS = new DataSet();
custDA.Fill(custDS, "Customers");
swindConn.Close();
return custDS;
}
////////////////////////////////////////////////////////////////////////
// The following example uses the RecitalCommand, RecitalDataAdapter and
// RecitalConnection, to select records from a database, and populate a
// DataSet with the selected rows. The filled DataSet is then returned.
// To accomplish this, the method is passed an initialized DataSet, a
// connection string, and a query string that is a SQL SELECT statement
public DataSet SelectRecitalRows(DataSet dataset, string connection, string query)
{
RecitalConnection conn = new RecitalConnection(connection);
SqlDataAdapter adapter = new RecitalDataAdapter();
adapter.SelectCommand = new RecitalCommand(query, conn);
adapter.Fill(dataset);
return dataset;
} 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:
 |
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. |
 |
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. |
 |
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
The 64bit port of Recital requires these libraries to allow access to 32bit Xbase and C-ISAM data files which are 32bit.
If you do not have these libraries installed you will either get a "can't find db.exe" or an "error loading shared libraries" when trying to run or license Recital.
Installing the ia32 shared libraries
Redhat EL 5 / Centos 5 / Fedora 10
-
Insert the Red Hat Enterprise Linux 5 Supplementary CD, which contains the ia32el package.
-
After the system has mounted the CD, change to the directory containing the Supplementary packages. For example:
cd /media/cdrom/Supplementary/
-
Install the ia32el package:
rpm -Uvh ia32el-<version>.ia64.rpm
yum install ia32el
Ubuntu / Debian
sudo apt-get install ia32-libs
In this article Chris Mavin, explains and details how to use the Recital Database Server with the Open Source Servlet Container Apache Tomcat.
Overview
PHP has exploded on the Internet, but its not the only way to create web applications and dynamic websites. Using Java Servlets, JavaServer Pages and Apache Tomcat you can develop web applications in a more powerful full featured Object Oriented Language, that is easier to debug, maintain, and improve.
Tomcat Installation
There are a number of popular Java application servers such as IBM Web Sphere and BEA WebLogic but today we will be talking about the use of Apache Tomcat 5, the Open Source implementation of the Java Servlet and JavaServer Pages technologies developed at the Apache Software Foundation. The Tomcat Servlet engine is the official reference implementation for both the Servlet and JSP specifications, which are developed by Sun under the Java Community Process. What this means is that the Tomcat Server implements the Servlet and JSP specifications as well or better than most commercial application servers.
Apache Tomcat is available for free but offers many of the same features that commercially available Web application containers boast.
Tomcat 5 supports the latest Servlet and JSP specifications, Servlet 2.4, and JSP 2.0, along with features such as:
-
Tomcat can run as a standalone webserver or a Servlet/JSP engine for other Web Servers.
-
Multiple connectors - for enabling multiple protocol handlers to access the same Servlet engine.
-
JNDI - The Java Naming and Domain Interface is supported.
-
Realms - Databases of usernames and passwords that identify valid users of a web application.
-
Virtual hosts - a single server can host applications for multiple domain names. You need to edit server.xml to configure virtual hosts.
-
Valve chains.
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JDBC - Tomcat can be configured to use any JDBC driver.
-
DBCP - Tomcat can use the Apache commons DBCP for connection pooling.
-
Servlet reloading (Tomcat monitors any changes to the classes deployed within that web server.)
-
HTTP functionality - Tomcat functions as a fully featured Web Server.
-
JMX, JSP and Struts-based administration.
Tomcat Installation
In this next two sections we will walk through the install and setup of Tomcat for use with the Recital database server.
To download Tomcat visit the Apache Tomcat web site is at http://jakarta.apache.org/tomcat.
Follow the download links to the binary for the hardware and operating system you require.
For Tomcat to function fully you need a full Java Development Kit (JDK). If you intend to simply run pre compiled JavaServer pages you can do so using just the Java Runtime Environment(JRE).
The JDK 1.5 is the preferred Java install to work with Tomcat 5, although it is possible to run Tomcat 5 with JDK 1.4 but you will have to download and install the compat archive available from the Tomcat website.
For the purpose of this article we will be downloading and using Tomcat 5 for Linux and JDK 5.0,
you can download the JDK at http://java.sun.com/javase/downloads/index.jsp.
Now we have the JDK, if the JAVA_HOME environment variable isn't set we need to set it to refer to the base JDK install directory.
Linux/Unix:
$ JAVA_HOME= /usr/lib/j2se/1.4/ $ EXPORT $JAVA_HOME
Windows NT/2000/XP:
Follow the following steps:
1. Open Control Panel.
2. Click the System icon.
3. Go to the Advanced tab.
4. Click the Environment Variables button.
5. Add the JAVA_HOME variable into the system environment variables.
The directory structure of a Tomcat installation comprises of the following:
/bin - Contains startup, shutdown and other scripts. /common - Common classes that the container and web applications can use. /conf - Contains Tomcat XML configuration files XML files. /logs - Serlvet container and application logs. /server - Classes used only by the Container. /shared - Classes shared by all web application. /webapps - Directory containing the web applications. /work - Temporary directory for files and directories.
The important files that you should know about are the following:
-
server.xml
The Tomcat Server main configuration file is the [tomcat install path]\conf\server.xml file. This file is mostly setup correctly for general use. It is within this file where you specify the port you wish to be running the server on. Later in this article I show you how to change the default port used from 8080 to port 80.
-
web.xml
The web.xml file provides the configuration for your web applications. There are two locations where the web.xml file is used,
web-inf\web.xml provides individual web application configurations and [tomcat install path]conf\web.xml contains the server wide configuration.
Setting up Tomcat for use
We'll start by changing the port that Tomcat will be listening on to 80.
To do this we need to edit [tomcat install path]/conf/server.xml and change the port attribute of the connector element from 8080 to 80.
After you have made the alteration the entry should read as:
<!-- Define a non-SSL HTTP/1.1 Connector on port 8080 --> <Connector port="80" maxHttpHeaderSize="8192"
Next we want to turn on Servlet reloading, this will cause the web application to be recompiled each time it is accessed, allowing us to make changes to the files without having to worry about if the page is being recompiled or not.
To enable this you need to edit [tomcat install path]/conf/context.xml and change <Context> element to <Context reloadable="true">.
After you have made the alteration the entry should read as:
<Context reloadable="true"> <WatchedResource>WEB-INF/web.xml</WatchedResource> </Context>
Next we want to enable the invoker Servlet.
The "invoker" Servlet executes anonymous Servlet classes that have not been defined in a web.xml file. Traditionally, this Servlet is mapped to the URL pattern "/servlet/*", but you can map it to other patterns as well. The extra path info portion of such a request must be the fully qualified class name of a Java class that implements Servlet, or the Servlet name of an existing Servlet definition.
To enable the invoker Servlet you need to edit the to [tomcat install path]/conf/web.xml and uncomment the Servlet and Servlet-mapping elements that map the invoker /servlet/*.
After you have made the alteration the entry should read as:
<servlet> <servlet-name>invoker</servlet-name> <servlet-class>org.apache.catalina.servlets.InvokerServlet</servlet-class> <init-param> <param-name>debug</param-name> <param-value>0</param-value> </init-param> <load-on-startup>2</load-on-startup> </servlet> <servlet-mapping> <servlet-name>invoker</servlet-name> <url-pattern>/servlet/*</url-pattern> </servlet-mapping>
If you are you not interested in setting up your own install of Tomcat there are prebuilt versions Tomcat that has all of the above changes already made, and has the test HTML, JSP, and Servlet files already bundled. Just unzip the file, set your JAVA_HOME
Next we will give Tomcat and your web applications access to the Recital JDBC driver.
For the purposes of this article we are going to install the Recital JDBC driver in the /[tomcat install path]/common/lib/ this gives Tomcat and your web applications access to the Recital JDBC driver. The driver can be installed in a number of places in the Tomcat tree, giving access to the driver to specific application or just to the web application and not the container. For more information refer to the Tomcat documentation.
Copy the recitalJDBC.jar which is located at /[recital install path]/drivers/recitalJDBC.jar to the /[tomcat install path]/common/lib/ directory.
Linux:
$cp /[recital install path]/drivers/recitalJDBC.jar /[tomcat install path]/common/lib/
Once you have completed all the steps detailed above, fire up the server using the script used by your platform's Tomcat installation.
Linux/Unix:
[tomcat install path]/bin/startup.sh
Windows:
[tomcat install path]/bin/startup
If you are having problems configuring your Tomcat Installation or would like more detail visit the online documentation a the Apache Tomcat site.
Example and Links
Now we have setup our Tomcat installation, lets get down to it with a JSP example which uses the Recital JDBC driver to access the demonstration database (southwind) shipped with the Recital Database Server.
The example provided below is a basic JDBC web application, where the user simply selects a supplier from the listbox and requests the products supplied by that supplier.
To run the example download and extract the tar archive or simple save each of the two jsp pages individually into /[tomcat install path]/webapps/ROOT/ on your server.
By enabling the invoker Servlet earlier we have removed the need to set the example up as a web application in the Tomcat configuration files.
You can now access the example web application at http://[Server Name]/supplier.jsp if the page doesn't display, check you have followed all the Tomcat installation steps detailed earlier in this article and then make sure both Tomcat and a licensed Recital UAS are running.
Downloads:
Archive: jspExample.tar
Right click and save as individual files and rename as .jsp files:
supplier.txt details.txt
Further Reading on JSP and JDBC can be found at http://www-128.ibm.com/developerworks/java/library/j-webdata/
Final Thoughts
Recital and Apache tomcat are a powerful combination, using Java Servlet technology you can separate application logic and the presentation extremely well. Tomcat, JSP, Java Servlets and the Recital database server form a robust platform independent, easily maintained and administered solution with which to unlock the power of your Recital, Foxpro, Foxbase, Clipper, RMS and C-SAM data.
Platforms supported
- Intel® / AMD™ 32 bit Linux
- Intel® / AMD™ 64 bit Linux
- HP PA-RISC HP-UX® 10.20 and above
- Sun® SPARC Solaris™ 8 and above
- HP Alpha OpenVMS 7.2-1 and above
- SCO® OpenServer 5.0.5 and above
- Sun® Intel® Solaris™ 10 and above
- IBM AIX® 4.3 and above
- HP Integrity OpenVMS 8.2-1 and above
- HP Intel® Itanium® HP-UX® 11.23 and above
- Mac OS X leopard 10.5 and above
Large File Support is available for Windows, Itanium HP-UX and Linux.
When stress testing our loadbalancer, i was unable to get more than 20 reliable ssh connections. The following error would be reported.
ssh_exchange_identification: Connection closed by remote host
The resolution for this is quite simple.
Edit the /etc/ssh/sshd_config file and increase the MaxStartups. On my server i set this to 200.
Edit /etc/sysctrl.conf and add the following line:
net.core.netdev_max_backlog = 3000
Then apply this change:
# sysctl -p
APPEND FROM TYPE CSV <file-name.csv>The TYPE keyword has now been enhanced to support a comma separated values (CSV) format
In Adobe's own words:"Adobe® AIR® is a cross-operating system runtime that lets developers combine HTML, Ajax, Adobe Flash®, and Adobe Flex® technologies to deploy rich Internet applications (RIAs) on the desktop."
The outcome of this combination of technologies is that developers can design and render quite beautiful user interfaces cross platform. For us desktop Linux users it is nice to have
an additional avenue for obtaining and running attractive desktop applications.Examples of great Adobe air applications are Adobe.com for My Desktop, TweetDeck and the Times Reader. You can download these applications and many more at the Adobe Marketplace.
The easiest way to install Adobe Air on Fedora 12 is to download the latest build from Adobe, click here.
Once you have downloaded the .bin file do the following at the shell:
su - chmod +x AdobeAIRInstaller.bin ./AdobeAIRInstaller.binOnce you have Air installed, there is a slight tweak you will have to do to get it running on Fedora 12, it is related to the security certificates. This can be remedied in one simple line at the shell prompt as root.
su - for c in /etc/opt/Adobe/certificates/crypt/*.0; do aucm -n $(basename $c) -t true; doneWhat this line is doing is using the aucm which is the Adobe Unix certificate manager to set the certificates installed as trusted.
You will now be able to go to the Adobe Marketplace and download and run Air applications without any issues.
Enjoy!