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Creating Data Access Services
Presented by
Ashraf Memon
Hands-on
Ashraf Memon, Ghulam Memon
1
Overview
• Writing data access service classes
in Java
• Generating service
• Deploying services with Apache
Axis
• Generating client files and testing
them
2
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.
3
Writing data access service
classes in Java
4
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
5
Code Anatomy
•
Load 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
–
•
Class.forName("com.mysql.jdbc.Driver");
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);
}
6
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";
}
7
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:
8
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>
9
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
10
Deploying services with Apache
Axis
• Type following on command line to navigate to
C:\tools\tomcat4.1\webapps\axis\WEBINF\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
11
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.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.
12
Next Chapter
• Creating Web Service to access
functionality of a tool
13