Multiple servlets vs parameterized service

I'd appreciate any advice/reccomendations anyone has on this topic
What are the trade offs in the following scenario where I have a set of related use cases I want my web app to handle. Is it best to have a servlet per use case (eg in a web store, I might have "buy item", "list products", "view cart") or is it best to have a single servlet and have that distinguish the particular use case from the URL/input parameters.
What are the overheads of multiple servlet objects in this scenario esp where as in the exampe above a "buy item" would affect the results of "view cart"
I realise I can use struts or similar to achieve the described effect, I'm more interested in the technical factors behind the choice above
thanks

its better if u can have only 1 servlet for alll the use case.it can be your Controller and this is called MVC arch. If u use seperate servlet for each use case then u have to repeat generic code in each servlet and u also be writing the business in the servlet thats worng. u should write all the business in seperate class which may be reused and this is called model in MVC.if u use single servlet it may become long but u can seperate in 2 or more but not each servlet for each use case.

Similar Messages

Problem with running multiple servlet in same webapplication with tomcat 3

Hi all,
I am using Tomcat 3.0 as webserver with jdk1.3, Servlet 2.0,
Templates for html file and oracle 8i on UNIX platform.
I have problem with multiple servlet running same webapplication.
There are two servlet used in my application. 1) GenServlet.class
and 2) ServletForPrinting.class
All of my pages go through GenServlet.class which reads some property files
and add header and footer in all pages.
I want reports without header & footer that is not possible through GenServlet in my application.
So I have used another servlet called ServletForPrinting --- just for reading html file.
It is as follow:
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class ServletForPrinting extends HttpServlet {
public void service (HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException
// set content-type header before accessing the Writer
response.setContentType("text/html");
PrintWriter out = response.getWriter();
File f1 = null;
String report = null;
String path = request.getPathInfo();
try{
String p = "/var/home/latif/proj/webapps/WEB-INF/classes" + path;
System.out.println(p);
f1 = new File(p);
p = null;
if (f1.exists()) {
FileReader fr = new FileReader(f1);
BufferedReader br = new BufferedReader(fr);
report = new String();
while ((report = br.readLine()) != null) {
out.println(report);
}catch(Exception e) {
out.close();
report = null;
path = null;
f1 = null;
} // end class
It works fine and display report properly.
But now Problem is that if report is refreshed many times subsequently,
WebServer will not take any new change in any of java file used in web-application.
It works with the previous class only and not with updated one.
Then I need to touch it. As soon as I touch it, webserver will take updated class file.
Anybody has any idea regarding these situation?
Is there any bug in my ServletForPrinting.java ?
Any solution ????? Please suggest me.
Suggestion from all are invited. That will help me a lot.
Thanks in advance
Deepalee.

Llisas wrote:
I solved the problem, I just had to wire the blocks in a sequential way (I still don't know why, but it works).
Feel free to delete this topic.
I would strongly suggest at least reading this tutorial to give you an idea of why your fix worked (or maybe only appeared to work). Myself, I never just throw up my hands and say, "Whatever," and wash my hands of the situation without trying my best to understand just what fixed it. Guranteed you'll run into the same/similar problem and this time your fix won't work.
Please do yourself a favor and try to understand why it is working now, and save yourself (or more likely, the next poor dev to work on this project) some heartache.
Bill
(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.

Adding multiple servlets under same application

Hi,
We are trying to add multiple servlets (2 to be precise) to an Application.
We are using j2ee1.3 server and deploytool for deploying the same.
Is it possible to have a single context root in which i'll be able to place both servlets with different aliases to access them?
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When I assign two different context roots to each servlet, they can function, but then the URL for each changes inspite of being in the same application.
Any suggestions are welcomed.
Thank you,
Manish.

Hi,
I did not quite follow the solution and I am wondering if it will solve a problem I am having.
I wish to define multple jax-rpc endpoints, but I want the classes servicing those endpoints to be able to communicate with one another. I tried placing them both in the same war and entering two endpoints in the jaxrpc-ri.xml file, but it didn't like the second endpoint entry being there.
Is there a way to do this?

Sharing config with Servlet and Web Services

Hi,
I am building a Servlet wrapper and a jaxrpc wrapper for my application, so that my client can invoke either servlet or web services to access my application.
my main application library is at WEB-INF/lib and both the servlet and
webservices are in WEB-INF/classes.
I am trying to make them sharing the same configuration file web.xml so that common attributes such as log file location can be read. I know Servlet can read the context and parameters but how to make my web services app to read it, since the web services are not servlet itself but it is invoked by the JAXRPC servlet????
Thanks

The early post may answer your question:
http://forum.java.sun.com/thread.jsp?forum=331&thread=266102

How to use my connection pool in multiple servlets?

I now have a functioning connection pool using these lines in a servlet:
private Connection getConnection(String lookup) throws NamingException, SQLException {
Context context = new InitialContext();
DataSource ds = (DataSource)context.lookup(lookup);
Connection ocon = ds.getConnection();
context.close();
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} // private Connection getConnection(String lookup) throws NamingException, SQLException {
========================
If I want to create additional servlets in the same web app which query the same database,
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Any suggestions are greatly appreciated.
Thank you.
Logan
************************************servlet example**********************************
package CraigsClasses;
import javax.servlet.*;
import javax.servlet.jsp.*;
import java.net.*;
import java.util.*;
import java.io.*;
import javax.servlet.http.*;
import java.sql.*;
import java.util.Date;
import java.text.*;
import javax.naming.*;
import javax.sql.DataSource;
public class CraigsMain extends HttpServlet {
public void init(ServletConfig config) throws ServletException {
super.init(config);
private Connection getConnection(String lookup) throws NamingException, SQLException {
Context context = new InitialContext();
DataSource ds = (DataSource)context.lookup(lookup);
Connection ocon = ds.getConnection();
context.close();
return ocon;
} // private Connection getConnection(String lookup) throws NamingException, SQLException {
// Process the http Get request
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String sql = "select formtitle from checkboxforms where cbformid = 157";
// error occurs at this line
Connection ocon = getConnection("java:comp/env/jdbc/CraigsList");
PreparedStatement pStmt = ocon.prepareStatement(sql);
ResultSet rs1 = pStmt.executeQuery();
rs1.next();
out.println(" " + rs1.getString(1));
rs1.close();
pStmt.close();
ocon.close();
} catch(SQLException sqle) {
System.err.println("sql exception error: " + sqle);
} catch(NamingException ne) {
System.err.println("naming exception error: " + ne);
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
=======================================================================

sjasja, Thank you for the reply. What you are suggesting is exactly what I have been looking for. But I'm pretty weak on how to make this separate con pool servlet work. My first attempt is shown below. It doesn't compile this line, which is obviously wrong:
public static Connection getConnection(String lookup) throws NamingException, SQLException {
Could you please help me with this servlet code? Thanks.
package CraigsClasses;
import javax.servlet.*;
import javax.servlet.jsp.*;
import java.net.*;
import java.io.*;
import javax.servlet.http.*;
import java.sql.*;
import javax.naming.*;
import javax.sql.DataSource;
public class ConPoolInit extends HttpServlet {
public void init(ServletConfig config) throws ServletException {
super.init(config);
try {
public static Connection getConnection(String lookup) throws NamingException, SQLException {
Context context = new InitialContext();
DataSource ds = (DataSource)context.lookup(lookup);
Connection ocon = ds.getConnection();
context.close();
return ocon;
} // private Connection getConnection(String lookup) throws NamingException, SQLException {
} catch(SQLException sqle) {
System.err.println("sql exception error: " + sqle);
} catch(NamingException ne) {
System.err.println("naming exception error: " + ne);
=======================================

EDI invoice failed for Service- multiple tax code at service item level

Hi Guys,
Please understand below scenarios, it is very critical to our client.
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line item which having the 3 services with tax code (P1-P1-P1 and P2-P2-P2 and (P2-P1-C1)
(P1=10%, P2=10% and C1=10%)
PO Outbound Idoc -
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tax rate at parent level also it carries indvidual service line item
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SES Outbound Idoc -
Similar tax codes(P1-P1-p1 and P2-P2-P2) - Carries total tax amount at
parent level segment and tax rate at parent item level also it carries
indvidual service line item tax amount and tax rate at service item
level
Mulitple tax codes(P2-P1-C1)- Carries only total tax amount at parent
level and no tax rate at parent level. It carries indvidual service
line item tax amount and tax rate at service item level
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asking for tax rate at parent level not at service item level.
It is working fine for similar tax code at service line item (e.g P1-P1-p1 for 3 services or P2-P2-P2 for all 3 services) but when we use the combination of tax code or multiple tax code at service line items (e.g. P2-P1-C1), the inbound Idoc gets failed.
Expectation - How EDI invoice posted for mulitple Services under one parent line item which having multiple tax codes at service item level
Thanks
Sanjay
9930851236

This is an ongoing problem with lots of clients - did anyone solve it ?

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regards

Hi
I want to know that whether the custom methods of servlet can be exposed as webservices or not?
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good morning,
Dont know if this is the right thread for this question but here it goes:
I was using Show Parameters Services 2 days ago to aquire a list of all current service names and it was returning info just fine.
I then proceeded to add 1 more 'serviceName' to the list and then ran an alter command to updae that list. It all worked.
But when i tried to reuse the Parameter services command again, it return an empty string. I did check in the appropriate table and the extra record is available with the other previouslly viewed service names.
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I hope this makes sence.
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Is this to do with using the SQL*Plus [SHOW PARAMETERS|http://download.oracle.com/docs/cd/B28359_01/server.111/b31189/ch12041.htm#sthref2262] command to list the current [SERVICE_NAMES|http://download.oracle.com/docs/cd/B28359_01/server.111/b28320/initparams217.htm] setting?

Upon computer startup: "Attempted to start multiple instances of the service"

Recently installed Diadem and there must be some sort of registry error. Whenever I startup I get the error "Attempted to start multiple instances of the service" anyone know the registry fix for this? Thanks!
Attachments:
NI startup error.jpg ‏16 KB

Hey Kyle,
Check your services and see what’s running. This can be done by going to Start>>Run and type “services.msc”. Then look for anything that starts with National Instruments or NI. Look to see if there are any entries running twice or if you are trying to call a service that is already running.
Nick
National Instruments
Applications Engineer

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null

Yes, you could start multiple servlets in JDeveloper IDE.
check online help
Open help system
Select the topic "Developing Java Servlets"
select "registering a servlet with web object manager"
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raghu

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I am still facing issue in displaying the restricted record in self service.
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I am trying to perform an update query on one field that uses multiple foreign key parameters from one table to update the other table. The data in all three foreign key parameter fields are not constant. Accuracy is absolutely critical. I tied this as well as other various scenarios with no success. Can anyone help?
Update A_table a
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I would check symbols by a user name and number of posts before calling anyone a hot shot, especially damorgon. 
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DDL matters because of indexes and associations. 
Data matters because it makes a difference on how SQL can be written. 
Reasons why an SQL statement don't work is because we aren't looking over your shoulder at your screen. 
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Servlet Calling Web Service

Hi
I need to call a web service via a servlet
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IB

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simply. When you "run it from the command line" you
are running it differently, with a different
classpath than you are when this is encountered. This
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directory-exploded equivalent) needs to contain all
the dependent classes/jars, and apparently you
haven't created that correctly.I have checked the classpath and it seems to be ok
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OS is Win XP
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java.lang.NoClassDefFoundError
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IB

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<servlet-mapping>
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Can't define init parameters for multiple servlets

I want to define init parameters for two servlets in the web.xml file but i only get null for my Login servlet
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In the code for you Login servlet, are you using the name "serverip2" to access the initial parameter ?
Thats the name you have used in the web.xml file.

Multiple servlets vs parameterized service

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