This article looks at the range of client access mechanisms for Windows that can be used with the Recital C-ISAM Bridge and details bridge configuration and usage.

Overview

Just because the format of data is regarded as 'legacy' does not make that data in any way obsolete. Modern client interfaces can not only extend the life of long-term data, but also provide different ways to analyse and gain advantage from that data.

Recital Corporation provides a range of solutions to interface to Informix compliant C-ISAM data on Linux or UNIX from Windows clients.

.NET

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Fig 1: Recital Mirage .NET application accessing the C-ISAM Demo table.

Recital offers two alternative ways to access C-ISAM data using Microsoft .NET:

The Recital .NET Data Provider is a managed Data Provider written in C# that provides full compatibility with the Microsoft SQLserver and OLE DB data providers that ship with the .NET framework. It is fully integrated with the Visual Studio .NET IDE supporting data binding and automatic code generation using the form designer. The Recital .NET Data Provider works in conjunction with the Recital Database Server for Linux or UNIX to access C-ISAM data.

Recital Mirage .NET is a complete solution for migrating, developing and deploying 4GL database applications. Recital Mirage .NET works in conjunction with the Recital Mirage .NET Application Server for Linux or UNIX to access C-ISAM data.

JDBC

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Fig 2: Java™ Swing JTable accessing the C-ISAM Demo table via the Recital JDBC Driver.

The Recital JDBC Driver is an all Java Type 4 JDBC 3.0 Driver, allowing you to access C-ISAM data from Java applets and applications. The Recital JDBC Driver works in conjunction with the Recital Database Server for Linux or UNIX to access C-ISAM data.

ODBC

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Fig 3: Microsoft® Office Excel 2003 Pivot Chart and Pivot Table accessing the C-ISAM Demo table via the Recital ODBC Driver.

The Recital ODBC Driver is an ODBC 3.0 Driver, allowing you to access C-ISAM data from your preferred ODBC based Windows applications. You can develop your own applications in languages such as C++ or Visual Basic, manipulate the data in a spreadsheet package or word processor document and design charts, graphs and reports. The Recital ODBC Driver works in conjunction with the Recital Database Server for Linux or UNIX to access C-ISAM data.

Configuring the Recital C-ISAM Bridge

Data access is achieved through a C-ISAM Bridge.  This requires the creation of an empty Recital table that has the same structure as the C-ISAM file and of a RecitalC-ISAM Bridge file.

On Linux and UNIX, Recital Terminal Developer and the Recital Database Server come complete with an example C-ISAM data file, C-ISAM index and Recital C-ISAM bridge that can be used for testing and as a template for configuring your own C-ISAM bridges.  The Recital Database Server also includes a bridge creation ini file.

Step 1:

Create a Recital table with the same structure as the C-ISAM file.  The fields/columns in the structure file must exactly match the data type and length of those in the C-ISAM file.  The Recital table will have one byte more in total record length due to the Recital record deletion marker.

To create the table, use the SQL CREATE TABLE command or the Recital Terminal Developer CREATE worksurface.  The SQL CREATE TABLE command can be called directly:

SQLExecDirect:
  In:      hstmt = 0x00761BE8,
    szSqlStr = "CREATE TABLE cisamdemo.str (DD Char(4)
              DESCRIPTION "Dd...", cbSqlStr = -3
  Return:  SQL_SUCCESS=0

or be included in a 4GL program:

// createtab.prg
CREATE TABLE cisamdemo.str;
    (DD Char(4) DESCRIPTION "Dd",;
     CONFIRM Char(6) DESCRIPTION "Confirm",;
     PROCDATE Char(6) DESCRIPTION "Procdate",;
     CONTROL Char(5) DESCRIPTION "Control",;
     DOLLARS Decimal(13,2) DESCRIPTION "Dollars",;
     DEALER Char(5) DESCRIPTION "Dealer",;
     TERRITORY Char(2) DESCRIPTION "Territory",;
     WOREP Char(12) DESCRIPTION "Worep",;
     CURRTRAN Char(3) DESCRIPTION "Currtran",;
     TRADDATE Char(6) DESCRIPTION "Traddate",;
     CITY Char(10) DESCRIPTION "City",;
     ACCOUNT Char(11) DESCRIPTION "Account",;
     PRETRAN Char(2) DESCRIPTION "Pretran",;
     AFSREP Char(14) DESCRIPTION "Afsrep",;
     REPKEY Char(9) DESCRIPTION "Repkey",;
     BRANCH Char(3) DESCRIPTION "Branch",;
     WODEALER Char(5) DESCRIPTION "Wodealer",;
     BANKCODE Char(2) DESCRIPTION "Bankcode",;
     COMMRATE Decimal(6,4) DESCRIPTION "Commrate",;
     NEWREP Char(1) DESCRIPTION "Newrep",;
     SETTLE Char(1) DESCRIPTION "Settle",;
     POSTDATE Char(6) DESCRIPTION "Postdate")
if file("cisamdemo.str")
    return .T.
else
    return .F.
endif
// end of createtab.prg

Server-side 4GL programs can be called by all clients, e.g. from a Java class with a JDBC connection:

//---------------------------------
//-- create_str.java --
//---------------------------------
import java.sql.*;
import java.io.*;
import Recital.sql.*;

public class create_str {

  public static void main(String argv[]) {
    try {
      new RecitalDriver();
      String url = "jdbc:Recital:" +
        "SERVERNAME=cisamserver;" +
        "DIRECTORY=/usr/recital/data/southwind;" +
        "USERNAME=user;" +
        "PASSWORD=password";
      Connection con = DriverManager.getConnection(url, "user", "pass");
      Statement stmt = con.createStatement();

      CallableStatement sp = con.prepareCall("{call createtab}");
      boolean res = sp.execute();
      String outParam = sp.getString(1);
      System.out.println("Returned "+outParam);
      sp.close();
      con.close();
    } catch (Exception e) {
      System.out.flush();
      System.err.flush();
      DriverManager.println("Driver exception: " + e.getMessage());
      e.printStackTrace();
    }
    try {
      System.out.println("Press any key to continue...");
      System.in.read();
    } catch(IOException ie) {
      ;
    }
  }
}

The table should be given a ‘.str’ file extension (rather than the default ‘.dbf’) to signify that this is a structure file only.

Please see the end of this article for information on matching Informix and Recital data types

Fig 4: Recital CREATE/MODIFY STRUCTURE worksurface for character mode table creation.

Step 2: Creating the Bridge File

If you have Recital installed on the server platform, the Bridge File can be created using the CREATE BRIDGE worksurface.  The corresponding command to modify the bridge file is MODIFY BRIDGE <bridge file>.  This is the cisamdemo.dbf bridge file in the CREATE/MODIFY BRIDGE WORKSURFACE:

> modify bridge cisamdemo.dbf

Fig 5: Recital CREATE BRIDGE/MODIFY BRIDGE worksurface for bridge creation.

For Recital Database Server clients, the Bridge File can be created using the Recital/SQL CREATE BRIDGE command:

Recital/SQL CREATE BRIDGE:

CREATE BRIDGE cisamdemo.dbf;
  TYPE "CISAM";
  EXTERNAL "cisamdemo.dat";
  METADATA "cisamdemo.str";
  ALIAS "cisamdemo"

or:

CREATE BRIDGE cisamdemo.dbf;
  AS "type=CISAM;external=cisamdemo.dat;metadata=cisamdemo.str;alias=cisamdemo"

The examples above assume that the C-ISAM file, the bridge file and the Recital structure file are all in the current working directory.  Full path information can be specified for the <externalname> and the <databasename>.  For added flexibility, environment variables can be used to determine the path at the time the bridge is opened.  Environment variables can be included for either or both the <externalname> and the <databasename>.  A colon should be specified between the environment variable and the file name.

e.g.

  CREATE BRIDGE cisamdemo.dbf;
  TYPE "CISAM";
  EXTERNAL "DB_DATADIR:cisamdemo";
  METADATA "DB_MIRAGE_PATH:cisamdemo.str";
  ALIAS "cisamdemo"

Recital CREATE BRIDGE/MODIFY BRIDGE worksurface:

Fig 6: Recital CREATE BRIDGE/MODIFY BRIDGE worksurface - using environment variables.

Using the Bridge

The Bridge can now be used.  To access the C-ISAM file, use the ‘alias’ specified in the Bridge definition.

SQL:

SELECT * FROM cisamdemo

Recital/4GL:

use cisamdemo

Indexes

The cisamdemo.dat file included in the Recital distributions for Linux and UNIX has three associated index keys in the cisamdemo.idx file:

Select area: 1
Database in use: cisamdemo
Alias: cisamdemo
Number of records: 4
Current record: 2
File Type: CISAM (C-ISAM)
Master Index: [cisamdemo.idx key #1]
Key: DD+CONFIRM+PROCDATE+CONTROL
Type: Character
Len: 21   (Unique)
Index: [cisamdemo.idx key #2]
Key: DD+SUBSTR(CONFIRM,2,5)+TRADDATE+STR(DOLLARS,13,2)
     +CURRTRAN+ACCOUNT
Type: Character
Len: 42
Index: [cisamdemo.idx key #3]
Key: DEALER+BRANCH+AFSREP+SUBSTR(PROCDATE,5,2)
     +SUBSTR(CONTROL,2,4)
Type: Character
Len: 28

The Recital C-ISAM bridge makes full use of the C-ISAM indexes.  SQL SELECT statements with WHERE clauses are optimized based on any of the existing indexes when possible.  The following ODBC SELECT call makes use of key #3 rather than sequentially searching through the data file.

SQLExecDirect:
  In:      hstmt = 0x00761BE8,
    szSqlStr = "select * from cisamdemo
      where dealer+branch+afsrep=' 00161   595-7912",
      cbSqlStr = -3
  Return:  SQL_SUCCESS=0

Get Data All:

"DD", "CONFIRM", "PROCDATE", "CONTROL", "DOLLARS", "DEALER", 
"TERRITORY", "WOREP", "CURRTRAN", "TRADDATE", "CITY", "ACCOUNT", 
"PRETRAN", "AFSREP", "REPKEY", "BRANCH", "WODEALER", "BANKCODE", 
"COMMRATE", "NEWREP", "SETTLE", "POSTDATE"

"0159", " 15522", "930312", "13356", 4992.60, "00161", "19", 
"", "210", "930305", "", "70000100009", "", "595-7912", 
"930315791", "", "", "59", 0.0000, "1", "", "930315"
1 row fetched from 22 columns.

Using the Recital/4GL, the primary index is set as the master index when the bridge is first opened.  Any secondary indexes can be selected using the SET ORDER TO <expN> command.  The Recital/4GL SEEK or FIND commands and SEEK() function can be used to search in the current master index.

> SET ORDER TO 3
Master index: [cisamdemo.idx key #3]
> SEEK “00161   595-7912”

Appendix 1: Data Types

Appendix 2: C-ISAM RDD Error Messages

The following errors relate to the use of the Recital CISAM Replaceable Database Driver (RDD).  They can be received as an ‘errno <expN>’ on Recital error messages:

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();
}

In this article Barry Mavin, CEO and Chief Software Architect for Recital, gives details on Working with user-defined Functions in the Recital Database Server.

Overview

User-defined functions (UDFs) are collections of statements written in the Recital 4GL (compatible with Visual FoxPro) stored under a name and saved in a Database. User-defined functions are just-in-time compiled by the Recital database engine. User-defined functions can be used in SQL statements to extend the power and flexibility of the inbuilt functions. Using the Database Administrator in Recital Enterprise Studio, you can easily create, view, modify, and test Stored Procedures, Triggers, and user-defined functions.

Tip

Creating and Editing user-defined functions

To create a new User-defined function,  right-click the Procedures node in the Databases tree of the Project Explorer and choose Create. To modify an existing User-defined function select the User-defined function 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 User-defined functions beginning with "f_xxx_", where xxx is the name of the table that they are associated with.

Testing the user-defined function

To test run the user-defined function, select it 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 it.

Example

Example: user-defined function "f_order_details_total".

////////////////////////////////////////////////////////////////////////
// example user-defined function
function f_order_details_total(pUnitprice, pQuantity, pDiscount)
    return (pUnitprice + pQuantity + pDiscount) > 0
endfunc

Example: using the user-defined function in a SQL SELECT statement.

////////////////////////////////////////////////////////////////////////
// sample code to use a user-defined function in a SQL SELECT statement
select * from customers where f_order_details_total(Unitprice, Quantity, Discount)

Using user-defined function libraries with the Recital Database Server

You can place all of the user-defined functions associated with a particular table into a procedure library. You then define an Open Trigger for the table that opens up the procedure library whenever the table is accessed. This is a much faster way of using user-defined functions as it reduces the amount of file open/close operations during a query and also simplifies development and maintenance.

By convertion we recommend that you should name the library using the convention "lib_xxx", where xxx is the name of the table that the library is associated with.

Example: procedure library in lib_order_details.

////////////////////////////////////////////////////////////////////////
// example user-defined functions
function f_order_details_total(pUnitprice, pQuantity, pDiscount)
    return (pUnitprice * pQuantity - pDiscount) > 0
endfunc

function f_order_details_diff(pUnitprice, pQuantity, pDiscount, pValue)
    return f_order_details_total(pUnitprice, pQuantity, pDiscount) - pValue
endfunc

Example: Open Trigger in dt_order_details_open.

////////////////////////////////////////////////////////////////////////
// This trigger will open up the procedure library when the table is opened
set procedure to lib_order_details additive

Example: Close Trigger in dt_order_details_close.

////////////////////////////////////////////////////////////////////////
// This trigger will close the procedure library when the table is closed
close procedure lib_order_details

Example: using the user-defined function in a SQL SELECT statement.

////////////////////////////////////////////////////////////////////////
// sample code to use a user-defined function in a SQL SELECT statement
select * from customers where f_order_details_total(Unitprice, Quantity, Discount)

User-defined functions can also be used with any of the Client Drivers that work with the Recital Database Server.