How to Retrieve Schema Sets from the Host File System

When a HostFileConnection is open, you can retrieve schema information about the target data by using the GetSchema method. GetSchema returns a DataTable object populated with the rows and columns that contain the schema information of the target of the current connection.

In addition, while a DBDataReader is open, you can retrieve schema information about the current result set by using the GetSchemaTable method. GetSchemaTable returns a DataTable object populated with rows and columns that contain the schema information for the current result set. The DataTable object contains one row for each column of the result set. Each column of the schema table row maps to a property of the column returned in the result set, where the ColumnName is the name of the property and the value of the column is the value of the property.

To retrieve schema sets from the host file system

1. Open a connection to the host file system with a call to HostFileConnection.

2. Call HostfileConnection.GetSchema to retrieve the schema data.

Example

The following code example demonstrates how to retrieve the schema sets from a connection object. Note that the ETCMLogging and HostFileUtils objects are developer-created objects that provide logging and utility functionality.

public void CNGetSchema(ETCMLogging.Logging logging, string host, string ccsid, string cnstring, HostFileUtils.Utils.HostFileType hostfiletype)  
        {  
            HostFileUtils.Oledb oledb = new HostFileUtils.Oledb();  
            HostFileUtils.Utils u = new HostFileUtils.Utils();  
            logging.LogInfo(host);  
            try  
            {  
                // Create connection.  
                HostFileConnection cn = oledb.CreateConnection(logging);  
                cn.ConnectionString = cnstring;  
                DataTable dt = cn.GetSchema();  
                if (dt.HasErrors)  
                {  
                    logging.LogFail("returned datatable has errors");  
                }  
                // Open the connection.  
                logging.LogInfo("Open Connection");  
                cn.Open();  
                DataTable dt2 = cn.GetSchema();  
                if (dt2.HasErrors)  
                {  
                    logging.LogFail("returned datatable has errors");  
                }  
                int rowcnt = dt.Rows.Count;  
                for (int i = 0; i < rowcnt; i++)  
                {  
                    int colcnt = dt.Rows[i].ItemArray.Length;  
                    for (int o = 0; o < colcnt; o++)  
                    {  
                        u.CompareValues(dt.Rows[i][o].ToString(), dt2.Rows[i][o].ToString(), logging);                          
                    }  
                }  
                // Close the open connection.  
                cn.Close();  
            }  
            catch (Exception e)  
            {  
                logging.LogInfo(e.Message);  
                logging.LogFail(e.StackTrace);  
            }  
        }  

See Also

Retrieving Information from the Host File System
BizTalk Adapter for Host Files Configuration