Jservlet Deployment in OAS

Question

Hi,
When we deploy a HTTPServlet to OAS, we can deploy it only as JServlet and after registering the servlet, if we look into the wrb.app, it says that the Execution string is wrks -s.
Because of this, when my applet communicates with the servlet and when the applet expects an object to be sent by the servlet, the applet gives a java.io.EOFException and in the web server I am able to see a new blank window popping up with the title 'wrks'.
What should the Exec String be set to in OAS for servlets?
Has anybody come across this problem? If so, can you pls tell me how to solve this?
Thx
SUdha

Answer 1

Hello ,
You do not explicitly need to set the Execution string for the jservlet cartride.
First ensure that the servlet by itself executes fine & is accessible from a browser.
Once this works, then you could access the servlet from a applet, using the java URL class.
Attaching a doc below which explains how to access Cartridges from a Java program
You are invoking a Oracle Application Server Cartridge to access the database
using a Java program.
From a Java program (Applet/Application), you could access database using JDBC
drivers. Invoking cartridges(PL/SQL, JAVA) to access the database from a Java
program, makes sense if,
a. The code required to access the database has already been written using
a cartridge.
b. The majority of the job done by the Java application is non-database.
c. You need to access database without a JDBC Driver and without using
Sql*Net(If you are using OCI Based JDBC drivers)
The major advantage of the above is code reusablity.
This is acheived by using the URLConnection class defined in the java.net
package, which allows the opening of a URL, and reading in the contents of the
URL. Accessing cartridges from a Java program is similar to accessing CGI
scripts from a Java program. Parameters can be passed to a CGI script using
the GET or the POST method. In the GET method, parameters are passed along with
the URL.
Example: http://oraclebl.oracle.com/cgi-bin/get_data?deptno=10
In the POST method, the parameters are passed to the Standard input of the CGI
script, which points to the data sent from the browser. The POST METHOD is
quickly making the GET METHOD obsolete because it's more versatile and has no
limitations on the amount of data that can be sent through the connection.
Given below is a example of a Applet accessing the PL/SQL cartridge to retreive
data from the database. The same concept could be used to access any other
cartridge(such as a Java cartridge) working on the HTTP protocol.
PL/SQL procedure accessed:
create or replace procedure get_emp_data(deptno in number) as
cursor c1(dept in number) is select empno, ename from scott.emp where deptno=dept;
begin
owa_util.mime_header('text/plain');
for i in c1(deptno) loop
htp.p(to_char(i.empno)| |' '| |i.ename);
end loop;
end;
Applet code accessing the above procedure using the PL/SQL cartridge.
package package4;
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.net.*;
import java.io.*;
public class Applet1 extends Applet {
Button button1 = new Button("Query Details"); /* Button to Query emp details */
TextField deptno = new TextField("",10); /* TextField to get the deptno */
FlowLayout flowLayout1 = new FlowLayout(); /* Initialize a Flowlayout class */
TextArea empDetails = new TextArea("",10,40); /* TextArea to display emp details queried */
public void init() {
setLayout(flowLayout1);
setSize(new Dimension(400, 329));
add(deptno);
add(button1);
button1.addActionListener(new button_listener(this));
add(empDetails);
void button1_actionPerformed(ActionEvent e) {
String t1 = empDetails.getText() ;
empDetails.replaceRange("",0,t1.length()); /* Initialize empdetails to "" */
try
URL url = new URL("http://winnt-nsc.in.oracle.com:8888/web_apps/plsql/get_emp_data");
/* Initialize the URL pointing to a PL/SQL cartridge */
URLConnection connection = url.openConnection();
connection.setDoOutput(true); /* Enable Output to the above URL Connection stream */
PrintWriter out = new PrintWriter(connection.getOutputStream());
out.print("deptno="+deptno.getText());
/* Send the deptno value to the output stream. This would be read by the cartridge
Using the POST method */
out.close();
String inputLine;
BufferedReader in = new BufferedReader( new InputStreamReader( connection.getInputStream()));
while ((inputLine = in.readLine()) != null) /* Retreive the URL content & initialize empDetails */
empDetails.append(inputLine+"\n");
in.close();
catch(Exception e1)
empDetails.append(e1.getMessage());
/* Listener to handle the Actions for the Query button */
class button_listener implements ActionListener {
Applet1 applet1;
button_listener(Applet1 applet1)
this.applet1=applet1;
public void actionPerformed(ActionEvent e) {
applet1.button1_actionPerformed(e);
Explaination:
a. Create the URL with the following.
URL url = new URL("http://winnt-nsc.in.oracle.com:8888/web_apps/plsql/
get_emp_data");
b. Call the URL object's openConnection method to connect to it. This
initializes a communication link between your Java program and the URL
over the network URLConnection connection = url.openConnection();
c. After the URL is opened, it creates two streams, one input stream to
read from the open connection, and one output stream to write to the open
connection. An input stream needs to be used to retreive the contents
of the URL. An output stream can be used to pass data to the URL
(such as Posting paraemeter values to the URL).getInputStream () and
getOutputStream methods of the URLConnection object could be used to get
the input & output streams respectively.
By default the input stream is enabled & the output stream is disabled.
You need to explicitly enable the output stream if reqiured by using the
setDoOutput method of the URLConnection object connection.setDoOutput
(true);
d. In the example the deptno is the parameter name, and the value is
retreived using deptno.getText().
Example uses the POST method to pass the parameters.
The parameter needs to be passed using the format
parameter_name=parameter_value, which is done by
out.print("deptno="+deptno.getText());
Paraemeters could be passed using the GET method, by just appending the
parameters in the above format to the URL. In this case, you do not need to use
the OutputStream of the URLConnection.
Example : http://winnt-nsc.in.oracle.com:8888/web_apps/plsql/
get_emp_data?deptno=10
Unless the URL length limitation is reached, try to use GET because of its
simplicity.
Oracle Support Services
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