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Creating Data Access Services

Creating Data Access Services. Presented by Ashraf Memon Hands-on Ashraf Memon, Ghulam Memon. Overview. Writing data access service classes in Java Generating service Deploying services with Apache Axis Generating client files and testing them. Writing data access service classes in Java.

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Creating Data Access Services

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  1. Creating Data Access Services Presented by Ashraf Memon Hands-on Ashraf Memon, Ghulam Memon

  2. Overview • Writing data access service classes in Java • Generating service • Deploying services with Apache Axis • Generating client files and testing them

  3. Writing data access service classes in Java • Data Access code in Java heavily relies on JDBC (Java Database Connectivity) • JDBC is a industry standard Java API from Sun Microsystems for communicating with almost all the database. • The driver is usually provided by the database company.

  4. Writing data access service classes in Java

  5. Writing data access service classes in Java • Sample Data Access class contains 1 function, which reads country data from PGAP database and generates XML for it • Method signature is • public String getData(String countryName) • Anatomy of class code follows on next slide • For complete source code check c:\data\csig05\ws\solutions\database\DBAccess.java

  6. Code Anatomy • Load JDBC Driver • Class.forName("com.mysql.jdbc.Driver"); • Establish databse conenction • Connection connection = DriverManager.getConnection( "jdbc:mysql://geon07.sdsc.edu:3306/test", "csig", "csig"); • Create jdbc statement • Statement stmt = connection.createStatement(); • Execute SQL query • stmt.executeQuery(sql); • Get database metadata (schema) ResultSetMetaData rsmd = records.getMetaData(); int numColumns = rsmd.getColumnCount(); String columnNames[] = new String[numColumns+1]; // Get the column names; column indices start from 1 for (int i=1; i<numColumns+1; i++) { columnNames[i] = rsmd.getColumnName(i); }

  7. Code Anatomy (contd) • Get result data (schema) while (records.next()) { xml += "<record>\r\n\t\t"; for (int i=1; i<numColumns+1; i++) { xml += "<" + columnNames[i] + ">" + records.getString(i) + "</" + columnNames[i] + ">\r\n\t\t"; } xml += "</record>\r\n\t"; }

  8. Testing the code • Navigate to solutions directory c:\data\csig05\ws\solutions • Open command prompt by right clicking on the database directory and selecting “Command Prompt Here” • Change to database directory by typing following at the command prompt cd database • Compile DBAccess.java file by typing following at command prompt javac DBAccess.java • Add mySQL JDBC driver to classpath by typing following at the command prompt C:\tools\Tomcat4.1\webapps\axis\WEB-INF\classes\classpath.bat • Run program by typing following at command prompt java DBAccess • Output should be of the form:

  9. Testing the code (contd) <table> <record> <country>GERMANY</country> <state></state> <area_code></area_code> <lat_dec>53.2</lat_dec> <lng_dec>9.6</lng_dec> <age_top>50000</age_top> <age_bot>50000</age_bot> <book>EUR</book> <plate_code>703</plate_code> <pgap_envi1>5</pgap_envi1> <pgap_envi2>5</pgap_envi2> <facies></facies> <formation_name>KONINGSMOOR</formation_name> <strat_reliability>Complete biostratigraphic control</strat_reliability> <geo_reliability>null</geo_reliability> <investigator></investigator> <Date_of_Entry>12-3-92</Date_of_Entry> <Date_of_Modified></Date_of_Modified> <comments></comments> <loc_no>12465</loc_no> <date_created>20010421160313</date_created> <date_modified>20010421000549</date_modified> </record> </table>

  10. Deploying your code as a web services with Apache Axis • Copy generated class file to C:\tools\tomcat4.1\webapps\axis\WEB-INF\classes\ • Open using any text editor deployDBAccess.wsdd from C:\tools\tomcat4.1\webapps\axis\WEB-INF\classes\ • Verify the content so that it matches the current service and its corresponding class

  11. Deploying services with Apache Axis • Type following on command line to navigate to C:\tools\tomcat4.1\webapps\axis\WEB-INF\classes\ cd C:\tools\tomcat4.1\webapps\axis\WEB-INF\classes\ • Execute deployment descriptor by typing deploy.bat deployDBAccess.wsdd at command prompt • This will deploy database webservice on Axis SOAP Server • Test it by going to http://localhost/axis/ and navigating to DBAccessService

  12. Generating client files and testing them • Change directory to c:\data\csig05\ws\solutions\database by typing “cd c:\data\csig05\ws\solutions\database” on the command prompt • Compile DBAccessServiceClient.javaby typing following at command prompt • javac DBAccessServiceClient.java • Execute Client by typing following at command prompt • java DBAccessServiceClient • Output should be similar to previous one.

  13. Next Chapter • Creating Web Service to access functionality of a tool

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