Creating Data Access Services

1
Creating Data Access Services

• Presented by
• Ashraf Memon
• Hands-on
• Ghulam Memon, Longjiang Ding

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\s
  olutions\database\DBAccess.java

6
Code Anatomy

• Load JDBC Driver
• Class.forName("com.mysql.jdbc.Driver")
• Establish databse conenction
• Connection connection DriverManager.getConnectio
  n(
• "jdbcmysql//geon07.sdsc.edu3306/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 StringnumColumns1
  
• // Get the column names column indices start
  from 1
• for (int i1 iltnumColumns1 i)
• columnNamesi rsmd.getColumnName(i)

7
Code Anatomy (contd)

• Get result data (schema)
• while (records.next())
• xml "ltrecordgt\r\n\t\t"
• for (int i1 iltnumColumns1 i)
• xml "lt" columnNamesi "gt"
  records.getString(i) "lt/" columnNamesi
  "gt\r\n\t\t"
• xml "lt/recordgt\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\classe
  s\classpath.bat
• Run program by typing following at command prompt
• java DBAccess
• Output should be of the form

9
Testing the code (contd)

• lttablegt
• ltrecordgt
• ltcountrygtGERMANYlt/countrygt
• ltstategtlt/stategt
• ltarea_codegtlt/area_codegt
• ltlat_decgt53.2lt/lat_decgt
• ltlng_decgt9.6lt/lng_decgt
• ltage_topgt50000lt/age_topgt
• ltage_botgt50000lt/age_botgt
• ltbookgtEURlt/bookgt
• ltplate_codegt703lt/plate_codegt
• ltpgap_envi1gt5lt/pgap_envi1gt
• ltpgap_envi2gt5lt/pgap_envi2gt
• ltfaciesgtlt/faciesgt
• ltformation_namegtKONINGSMOORlt/formation_namegt
• ltstrat_reliabilitygtComplete biostratigraphic
  controllt/strat_reliabilitygt
• ltgeo_reliabilitygtnulllt/geo_reliabilitygt
• ltinvestigatorgtlt/investigatorgt
• ltDate_of_Entrygt12-3-92lt/Date_of_Entrygt

10
Deploying your code as a web services with Apache
Axis

• Copy generated class file to C\tools\tomcat4.1\we
  bapps\axis\WEB-INF\classes\
• Open using any text editor deployDBAccess.wsdd
  from C\tools\tomcat4.1\webapps\axis\WEB-INF\class
  es\
• 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\classe
  s\
• 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\da
  tabase by typing cd c\data\csig05\ws\solutions\d
  atabase on the command prompt
• Compile DBAccessServiceClient.java by 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