Below is a Java Server Page (JSP) that I wrote that can be used as a SQL Responder running in a Java Web Server such as Apache Tomcat. The JSP is expecting several input parameters: sqlquery, maxrows, querytype, etc. via http post protocol. The servlet then does a SQL lookup based off of the input parameter passed to it. After the SQL database returns the data to the JSP. The JSP then returns a tcl list via http response to the calling process, usually a Tcl Interpreter. The technologies used in the servlet are JDBC and Jacl. I would not recommend using this serlvet over the internet because of security reasons. You could update the servlet to use SSL or https. If anyone has ideas on how to do update the servlet to make it more secure using https then feel free to update the code below. One nice thing about JSPs or Java Servlets are that they are multi-threaded by nature. This JSP engine should be able to handle many concurrent requests. 

Scott Nichols.
scott.nichols@attbi.com

The JSP is expecting the following input parameters via HTTP POST:

 1. sqlquery
 This is the SQL query to send to the DBS. This parameter is required. If it is not included NULL is returned to the calling process.

 2. connection
 This is the JDBC datasource connection string to use. This paramater can be an ODBC DSN connection that exists on the same computer as where the JSP is running.
 The default value is: "jdbc:odbc:Northwind"

 3. username
 This is the username to login into the DBS with.
 The default value is "sa"

 4. password
 This is the password to use with the login into the DBS.
 The default value is NULL or ""

 5. querytype
 This is the type of SQL query that is being run. This can be either select, insert, update, or delete.
 The default value is select. NOTE: An error may be returned if the SQL query does not match the query type parameter.

 6. maxrows
 This is the maximum rows to be returned as a Tcl list.
 The default value is 1000 rows.

Here is the source code for the JSP page. To install it simply copy the contents into your clipboard and then past into a JSP file and save it a working Java Web Server such as Apache Tomcat. Which can be downloaded for free at Apache.org. This JSP requires the JACL library package to be installed and in the Java's library path.
 
 <%@ page import="java.io.*" %>
 <%@ page import="java.util.*" %>
 <%@ page import="java.sql.*" %>
 <%@ page import="tcl.lang.*" %>

 <%
 String sSQLQuery = "";
 String sError = "";
 String sMessage = "";
 Connection con;
 Statement stmt;
 int i=0;
 ResultSet rs;
 String sbgcolor = "#D3D3D3";
 String sFontcolor = "White";

 String sTable = "";
 TclObject   row;
 TclObject	rows=null;
 Interp interp;
 interp = new Interp();

 if (request.getParameter("sqlquery") != null)
 {
	// Read the SQL Query
	sSQLQuery = request.getParameter("sqlquery");

	try {
		// Load the standard JDBC driver provided by SUN
		Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
		try {
			// Read the connection string, username and password posted from the HTML form.
			if ((request.getParameter("connection") != null) &&
			    (request.getParameter("username") != null) &&
			    (request.getParameter("password") != null))

				// Connect to the ODBC datasource.
				con = DriverManager.getConnection(request.getParameter("connection"),request.getParameter("username"),request.getParameter("password"));
			else
				con = DriverManager.getConnection("jdbc:odbc:Northwind","sa","");

			// Create a connection statment.
			stmt = con.createStatement();

			String queryType;

			if (request.getParameter("querytype") != null)
				queryType = request.getParameter("querytype");
			else
				queryType = "select";

			// Do we do a Select SQL Query or  an Update, Delete or Insert SQL Query?
			if ( queryType.compareTo("select") == 0)
			{

				// Read how many SQL rows the user wants returned.
				if (request.getParameter("maxrows") != null)
					stmt.setMaxRows(Integer.parseInt(request.getParameter("maxrows")));
				else
					stmt.setMaxRows(1000);

				// Submit the SQL Select Query
				rs = stmt.executeQuery(sSQLQuery);
				ResultSetMetaData meta = rs.getMetaData();

				// Parse the column headers from the result set (meta-data) and build the header
				// of the HTML table
				int iColumns = meta.getColumnCount();
				rows = TclList.newInstance();
				row = TclList.newInstance();
				TclList.append(interp, row,TclString.newInstance("SUCCEEDED"));
				TclList.append(interp, rows,row);
				row = TclList.newInstance();
				for (int colNumber=1; colNumber<=iColumns; colNumber++)
				{
					// sTable = sTable + "<TD><B><font color=\"Yellow\">" + meta.getColumnLabel(colNumber) + "</font></B></TD>\n";
					TclList.append(interp, row,TclString.newInstance(meta.getColumnLabel(colNumber)));
				}
				TclList.append(interp, rows,row);

				// Build the body of the HTML Table
				while (rs.next())
				{
					row = TclList.newInstance();
					for (int colNumber=1; colNumber<=iColumns; colNumber++)
					{
						// sTable = sTable + "<TD><B><font color=\"" + sFontcolor + "\">" + rs.getString(colNumber) + "</font></B></TD>\n";
						TclList.append(interp, row,TclString.newInstance(rs.getString(colNumber)));
					}
					TclList.append(interp, rows,row);
				}

				// Close the result set
				rs.close();
			}
			else
			{
				// Execute an UPDATE, DELETE, or Insert Query.
				i = stmt.executeUpdate(sSQLQuery);
			}
			// Close the open database connections.
			stmt.close();
			con.close();
		}
		catch (SQLException se) {
			System.out.println("SqlException:" + se.getMessage());
			se.printStackTrace(System.out);
			sError =  "SqlException:" + se.getMessage();

			rows = TclList.newInstance();

			TclList.append(interp, rows,TclString.newInstance("FAILED"));
			TclList.append(interp, rows,TclString.newInstance(se.getMessage()));
		}
	}
	catch (ClassNotFoundException e) {
		System.out.println("ClassNotFound:" + e.getMessage());
		sError = "ClassNotFound:" + e.getMessage();

		rows = TclList.newInstance();

		TclList.append(interp, rows,TclString.newInstance("FAILED"));
		TclList.append(interp, rows,TclString.newInstance(e.getMessage()));

	}
 }
 %>
 <%=rows.toString()%>

And here's some example Tcl code on how to call the JSP SQLServlet using http protocol. This example requires a ODBC DSN connection created on the server where the JSP is running. Scott Nichols

 package require http

 puts "--------------------------------Start http SQL Request--------------------------------------------------------------"

 # Format the JSP URL
 set postData [::http::formatQuery sqlquery "Select * from Orders" connection "jdbc:odbc:Northwind" username sa  password "" querytype select maxrows 50]

 puts $postData

 set response [::http::geturl "http://Insert JSP URL" -query $postData]

 upvar #0 $response state

 puts $state(status)
 puts $state(body)

 if { [string match "ok" $state(status)] } {

 set status [lindex $state(body) 0]

 if { [string match "SUCCEEDED" $status] } {

    set rows [string trim $state(body)]

    if {[llength $rows] > 1} {
        set bFailed 0
        set P_status succeeded
        set P_result $rows
    } else {
        # This is a nomatch condition
        set P_status failed
        lappend P_status nomatch
    }

 } else {
    set P_status failed
    lappend P_status [lindex $state(body) 1]
 }

 } else {
    set P_status failed
 }


 puts "--------------------------------End http SQL Request----------------------------------------------------------------"

Please rename this page to SQLServlet. Thanks.

[Category Jacl]