Servlets and Application Beans

Hi I'm reviewing some sample code that was originally done as a JSF application. I however will not be doing a JSF application but rather a simple Model 2 architecture using servlets. I'm trying to confirm what the equivalent to an application managed and session beans in JSF would be in a servlet environment. For example the following xml in a JSF app...
- <managed-bean>
<managed-bean-name>jpaResourceBean</managed-bean-name>
<managed-bean-class>oracle.toplink.jpa.example.inventory.services.impl.JPAResourceBean</managed-bean-class>
<managed-bean-scope>application</managed-bean-scope>
</managed-bean>
- <managed-bean>
<managed-bean-name>inventoryService</managed-bean-name>
<managed-bean-class>oracle.toplink.jpa.example.inventory.services.impl.ManagedInventoryBean</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
- <managed-property>
<property-name>jpaResourceBean</property-name>
<value>#{jpaResourceBean}</value>
</managed-propert
Would that simple be using the servlet context and session variables? Any other tips on the right way to do this?
Thanks

fsa3 wrote:
I'm trying to confirm what the equivalent to an application managed and session beans in JSF would be in a servlet environment.JSF application scoped beans are stored as ServletContext attributes and JSF session scoped beans are stored as HttpSession attributes. So do the same in a servlet and you're fine.

Similar Messages

Sharing an object/class bewteen servlets and applications

Hi there,
I wish to know how to share a class/object between all
types of other classes, be they applications or servlets, but I encounter the following problem.
Basically, if I instantiate the common class using, say a servlet, then when I try to gain a handle on the instance of that class from an application, the application creates a new(or it's own) instance. Similarly, if I instantiate first within an application.
How do I prevent this from happening?
The actual class files for both the application and servlets are all the same.
Appreciate the help,
Fintan.

I am actually implementing the singleton pattern in
this common class.ok, that clarifies the issue a bit...
The RMI route seems to me to be a bit too much work > as a solution to a very simple concept.actually, it's really not a simple concept. What you really want isn't just an application singleton, where there is one instance in the application/servlet JVM. What you really want is more along the lines of a universal singleton, where there is only one instance for ALL applications/servlets...
Interestingly, if I run two java apps side by side in
two DOS windows that each call a getInstance
method in common singleton, both apps create their
own instance.
How come? Separate instances of VM?Yes, this is exactly correct. The same is true of C++ Singletons; if you start a second application it will create another instance of the Singleton because one does not yet exist in the application.
How do I get aroun this one?Like I said, think of it as a universal singleton. Consider Verisign a universal singleton--everyone comes to them for certificates. How does this run? Well, truthfully, Verisign operates as a service, right? So you need some way of setting up a service that really holds onto the object and brokers (aha, 5 dollar word!) who has access to it, who can modify it, and who can read from it. This leads you to a few options... RMI, CORBA, or writing your own object server.
Networking is really easy in Java, so here's another option... You can set up a server that listens for messages on a specific socket/port with whatever protocol you specify to get/set values. Have the server run on only one specific machine. Then you can have all the servlets and applications come to the machine to get the information.
Gee, this sounds like a back-end database. =)
If all this is too complex, maybe you need to rethink the design... do you really need to have the exact same object shared between all application/servlet instances? Or is it acceptable to just make sure they all contain the same data?
If what you really want is a real-time data update scheme, then you probably want something like a subscribe-publish architecture where the one server publishes the origainal data. Then when a client updates the server, the server posts an update message to all the clients, who then in turn update their internal data.
Anyway, I'm just throwing out some ideas. I'm sure you can come up with some better ones of your own since you know what your requirements are. =)
Once again appreciate the help!I hope it actually was. =)
--David

Refresh code servlet and session bean don't work more.

Hi all,
I'm not sure if it's a problem with oc4j, but maybe someone can
help me.
I'm working with Jdev 10.1.3.0.4(SU4) on Fedora Core 5 and XP.
I create an application with a servlet, ran the servlet and
all things work. Change the code in servlet, recompile and refresh
the browser and all work fine.
But, when I create a CMP Entity Beans from Tables with EJB 3.0 on
a simple table and change the code in servlet, recompile and refresh
the browser the code of servlet stay old. Just restart oc4j make the changes
work. Changes on entity bean ou session beans or junit class take
the same problem, just after the restart oc4j do the job.
Is it a bug? Is thera a workaround?
Thanks for all,
Luciano

Oh and before you tell me to just use XSLT on the output to get it how I want it, or use XMLType views where the XML is generated on the database server, I can assure you I know both of those options, but they both cut into the profitability of running a high-volume service.
The XSU (XML SQL Utility for those keyword searching) is great in that I can host it on middle tier servers in any servlet container and take the burden of XML generation and parsing off the $40K/processor server. If I can further take the burden of XSLT transformations off the middle tier, so much the better... The XSU allows me to run the same throughput on probably something like half the hardware and a tenth the licensing fees.
So here's a huge vote in favor of continued development of the XSU...I would also like it to handle XML attributes on inserts/updates rather than having to use the "canonical" element form.
If anyone knows an even better approach, please speak up!

Differences between servlet and backing bean

Could anyone please tell me whether everywhere that servlet can be used, backing bean and JSF can be used too? Are JSF and backing beans the new alternatives for JSP and servlets? please clarify the relations between these concepts for me.
Thanks
Laura

Laura_Jlover wrote:
Thank you. You mean backing beans can do every thing that servlets can do? Yes.
JSF pages can work with servlets? Strictly speaking, every JSF page gets passed through the FacesServlet which does all the task. The lifecycle, creating the FacesContext, putting the request parameters in backing beans, rendering the response, etcetera.
what are the advantages of servlet and the advantages of backing beans? what's the disadvantages? In general, which one is better?In context of JSF, you should be using backing beans, not Servlets. There is nothing what a Servlet can offer you as an advantage in the JSF context. It is simply not an option/alternative. You can't even call a Servlet (directly) using a JSF h:form. You, however, can access backing beans in any JSP or Servlet outside the JSF context.
Just carefully read the JSF specification or buy a JSF book and the picture will be clear.
JSF spec: [http://jcp.org/aboutJava/communityprocess/final/jsr252/index.html].
JSF book: [http://www.amazon.com/JavaServer-Faces-Complete-Reference/dp/0072262400].

User parameter are not show in database using Servlet and java Bean

Hello Sir,
when I insert the parameter in run time, weblogic server and JSP show that parameter are saved.
Allthough row increment in database but they not show in database.
Here My Code:
login.html:
<html>
<head>
<title>A simple JSP application</title>
<head>
<body>
<form method="get" action="tmp" >
Name: <input type="text" name="user">
Password: <input type="password" name="pass">
<input type="Submit" value="Submit">
</form>
</body>
</html>LoginServlet.java:import javax.servlet.*;
import javax.servlet.http.*;
public class LoginServlet extends HttpServlet{
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException{
try
String user=request.getParameter("user");
String pass=request.getParameter("pass");
co.SimpleBean st = new co.SimpleBean();
st.setuserName(user);
st.setpassword(pass);
request.setAttribute("user",st);
request.setAttribute("pass",st);
RequestDispatcher dispatcher1 =request.getRequestDispatcher("submit.jsp");
dispatcher1.forward(request,response);
catch(Exception e)
e.printStackTrace();
}SimpleBean.java:
package co;
import java.util.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
import java.util.*;
public class SimpleBean {
private String user="";
private String pass="";
private String s="";
public String getuserName() {
return user;
public void setuserName(String user) {
this.user = user;
public String getpassword() {
return pass;
public void setpassword(String Pass) {
this.pass= pass ;
public String issueData()
try
System.out.println("Printed*************************************************************");
Class.forName("oracle.jdbc.driver.OracleDriver");
System.out.println("Connection loaded");
Connection con=DriverManager.getConnection("jdbc:oracle:thin:@VijayKumar-PC:1521:XE","SYSTEM","SYSTEM");
System.out.println("Connection created");
PreparedStatement st=con.prepareStatement("insert into vij2 values(?,?)");
System.out.println("~~~~~~~~~~~~~~~~~~~~");
String NAME=getuserName();
st.setString(1,NAME);
String PASSWORD=getpassword();
st.setString(2,PASSWORD);
st.executeUpdate();
System.out.println("Query Executed");
con.close();
s= "Your logging is saved in DB ";
System.out.println("Your logging is saved in DB *****************");
return(s);
catch(Exception e)
e.printStackTrace();
return "failed";
}submit.jsp:This is Submit page
<jsp:useBean id="st" class="co.SimpleBean"/>
<jsp:setProperty name="st" property="*" />
<jsp:getProperty name="st" property="userName" /> <br>
<jsp:getProperty name="st" property="password" /> <br>
<% st.issueData();%>
<%
out.println("Ur data is saved in DB");
%>Please Help me.
Thanks.

Ok, this seems to be a long and convoluted path to do absolutely nothing.
You submit the form.
You run a servlet that gets the parameters correctly (good), creates a SimpleBean (good) and then sets this into request attribute space under the names "user" and "pass" - (why?)
You then forward to the jsp: submit.jsp.
Submit.jsp creates a new SimpleBean, and attempts to populate it with <jsp:setProperty>. You then call the issueData method on it.
Your complaint: Rows are being created in the database which have empty string values instead of the parameters you have passed.
So, why are the values blank? Where do you think these values should be coming from?
Looking at SimpleBean we find one mistake - you have mis-named your get/set methods.
To properly follow java beans standards, you should use camel-case for your methods.
Rather than getuserName() the method should be getUserName(). getpassword() should be getPassword() etc etc.
The method getUserName() defines a property "userName" for the bean.
Once that is fixed, lets go to submit.jsp. The <jsp:setProperty> statement will try and set all properties of the bean from the request parameters.
There are no request parameters "userName" or "password" so those values don't get set in the bean, therefore it uses their default value of empty string - "".
There ARE request parameters called "user" and "pass" but because they aren't properties of the bean, they get ignored.
As a result, the values are empty string, and that is exactly what gets inserted into the database.
Ways to fix this
1 - rename your parameters on your form to be "userName" and "password" to match the bean. That way the <jsp:setProperty> tag will populate them properly.
or
2 - Call issueData() method from your servlet after you have created the SimpleBean. Better in my opinion as you then don't have any scriptlet code on a JSP page.
Cheers,
evnafets

Problem with servlet and application program

i have this error appearing in my browser...
i have this feeling it is about the application, but if application alone, i now having some trouble running it, once i bind it with an applet i always have this message:
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
java.lang.NullPointerException
     exString.triming(exString.java:12)
     exString.geta(exString.java:113)
     forplay.play(forplay.java:9)
     textServe.doGet(textServe.java:14)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
     org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServlet.java:419)
     org.apache.catalina.servlets.InvokerServlet.doGet(InvokerServlet.java:133)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.17 logs.
i know this is a simple problem...
how come my application is having some difficulty in running my application...
this servlet by the way is a get parameter base...

Its caused cuz ur exString is null..
rgds
shanu

Problem with JSP and Java Servlet Web Application....

Hi every body....
I av developed a web based application with java (jsp and Java Servlets)....
that was working fine on Lane and Local Host....
But when i upload on internet with unix package my servlets and Java Beans are not working .....
also not access database which i developed on My Sql....
M using cpanel support on web server
Plz gave me solution...
Thanx looking forward Adnan

You need to elaborate "not working" in developer's perspective instead of in user's perspective.

Servlet as java bean

i have written my jdbc connectivity code in a servlet..n want to use it as a bean can i use it as a bean plz help me out.

I have a feeling you're going to be out of luck there. They are somewhat different beasts.
If you mean a bean for access from a JSP? Write one, and (dare I say it) copy/paste your db access "codes". Or use the standard taglib JSTL, it has data access stuff for you.
Later, of course, you'll come back and say to me "the performance of this bean in my jsp sucks"...
...so my real recommendation is: read the documentation and be clear about the difference between a servlet and a bean... (which I would imagine, of course, is just the advice you don't want to hear).
/k1

Directory structure for servlets and webservices in one application

hi,
Can any one help me for creating servlets and webservices in one
application and deploying in Jboss 4.2.0.
I want to know exactly what is the directory structure for creating this
application and what are the additional .xml files for deploying this application.
if any one know this answere please tell the answere.

I figured out a solution - it's a problem of policies. In detail: Server1's codebase entry (file:) refers to the class directory of Server1's project. In the simple case of only Client1, which has no codebase entry, it works fine without a file permission on the side of Server1. In the complex case of Client1+Server2, which has to have a codebase entry (file:) refering to the class directory of the Server2's project on a separate machine, for exactly the same method call from Client1 to Server1 a file permission entry on the side of Server1 is needed for Server1's class directory. But WHY ???
It seems to be a little confusing with the codebase entries, many of the posts are contrary to others and to my personal experiences. Some comments given by Adrian Colley throw a little light upon some aspects. Is there anybody, who can explain the whole topic, when, why, and which part of RMI application deals with codebase entries, also in case of not dynamic code downloading ? May be there is also a reference into the java docs, which I didn't found up to now.
Thanks in advance
Axel

When to use servlets and jsp in an application like shoping cart?

Hi All
I m going to design and implement a web application using servelts and jsp. I am still at its requirements analyze stage.
The application is almost likely a shopping cart. So if any of you have the deep knowledge about this domain with servlets and jsp please help me for a good design. What I realy need to know is that
1. what are the core requirements for a shoping cart ?
2. use cases ?
3. best way to follow mvc with servlets and jsp for it?
you can answer to this at the abstract level. no need to go in detail.
if you have any documents like design and use cases mail me to [email protected]
your cooperation is highly appreciated in this regards.

Look into this kid
http://www.apl.jhu.edu/~hall/java/Servlet-Tutorial/Servlet-Tutorial-Session-Tracking.htm

Clustering and Application/Servlet Singletons...Replicated?

Are static servlet and instance attributes replicated to servlet instances
          in cluster?
          We have seen some behavior which suggest no?
          Assuming all instance and static variables are serializable or atomic types,
          are they replicated?
          If not, how is application/servlet level state replicated? servletcontext?
          -phil ([email protected])
          [Phillip A. Lindsay.vcf]


"Phillip A. Lindsay" wrote:
          > Are static servlet and instance attributes replicated to servlet instances
          > in cluster?
          Each node will have its own class/classloader tuple and therefore its own set
          of static and instance attributes. The singleton effect can be achieved by
          binding
          an object into a namespace at a well-known point. It can be argued that a
          singleton
          should be replicated but then it wouldn't be a "single" singleton.
          Cheers
          Alex
          mailto:[email protected] // Consulting services available

Send data from bean to servlet and get results back to bean

Hi,
I'm new to this helpful forum and, as long as I'm practicing with JFS and Java Beans and Servlets, I really need some help about the following crappy issue.
I made a JSP login page called "LoginPage.jsp" (using "Visual Web JSF Page" tool in NetBeans 6.0), and the action associated to the "Login" button pression is defined in the associated Java Bean "LoginPage.java":
Code from "LoginPage.jsp":
<webuijsf:button actionExpression="#{LoginPage.loginButton_action}" binding="#{LoginPage.loginButton}" id="loginButton" primary="true" style="height: 24px; left: 383px; top: 192px; position: absolute; width: 96px" text="Login"/>
Code from "LoginPage.java":
public String loginButton_action()
    if (usernameField.equals("guest") && passwordField.equals("guest")) // this control should be done by a servlet, not here!
        return "loginOK"; // this is the outcome for faces-config.xml that will lead to a "Welcome.jsp" page
    else
        return "loginERROR"; // this is the outcome for faces-config.xml that will lead to a "Error.jsp" page
...Now, the problem is that the username and password control should not be done by the bean itself, but by a servlet (call it "LoginServlet.java").
In a few words, what I mean is that once the user writes username and password and presses the "Login" button, the called "loginButton_action()" forwards all the needed data to the servlet "LoginServlet.java", the servlet does the complete checks about login validity then prepares the result (it could be a string reporting "OK" or whatever else) and send it back to the bean "LoginPage.java", so that the flow can continue.
My problem is that I absolutely don't know how to make a bean and a servlet communicate in both ways and respectively exchange data.
Thanks in advance for any help, it will really be appreciated.

Google for passing values in request and session.

MVC model in Web systems and applications

MVC model in Web systems and applications
Object-oriented design model is experience, MVC idea is a user interface for the original. This article discusses how the major application areas in the new Web design patterns and the use of MVC framework. The article first introduced the concept of design patterns and characteristics, and MVC architecture design concepts and analysis of the MVC framework contains several key models. Based on the characteristics of Web applications on how to use patterns and MVC framework made some design ideas.??
1. Introduction
1.1 design model
Object-oriented technology and the emergence of software applications has greatly enhanced the trusted and software quality. Object-oriented programming than previous models to various programming simple and efficient, but the object-oriented design methodology than the previous design methods to complex and much more skill, a good design should be both on the issue of gender, but also to take full account of the problems and needs sufficient interoperability. In the past 10 years, people in the object-oriented technology and the practical application of research to explore certain issues in relation to the creation of a number of good solutions, the so-called object-oriented design patterns. Object-oriented technology is one of the purposes of enhancing the software trusted, and to design model, design programmes in important positions from a deeper sense of meaning and essence embodies trusted. There are many people in the design model definition, which cited Christopher Alexander is the largest design model definition : Each design model is a tripartite rule, which expresses a contextual environment (Context), a problem and a solution. Design models generally following basic elements : model name, the purpose solution effect 1995-1998 code and related design models. There are several classifications design patterns can be divided into a model based on the purpose (Creational), structural type (Structural) and the type of behaviour (Behavioral) three. It is mainly used in the creation of a model-based object model-based structure to deal primarily with the category or combination of objects, used to describe behavior-based model is the main target for the category or how stress and how to allocate responsibilities. Design patterns can be divided into categories based on the scope and target mode model type model dealing with the relationship between the categories and sub-categories, these relations through the establishment of succession in Translation moment to be finalized, are static. Model is targeted at addressing the relationship between the moment of change these relations in the operation, more dynamic. Model features : through the experience acquired in a structured format to write down, avoid encountering the same problems on the first design, exist in different abstract level, in continuous improvement, can be trusted artificial product for the design and best practice in the world to be combined to address larger issues.
1.2 MVC framework
MVC was first used in a user interface Smalltalk-80 China. M representative models Model, representatives maps View V, C representatives controller Controller. MVC trusted code with the aim of increasing the rate of data reduction expressed, the data describing the operation and application coupled degrees. Also makes software Keweihuxing, restorative, expansionary, flexibility and packaging of greatly enhanced. Single-user applications are usually incident-driven user interface to the organizational structure. Staff development tool with an interface painting of a user interface interface code based on user input and then prepare to implement the corresponding moves, many interactive development environment encouraged to do so, because it emphasizes first and then a functional interface. Some software design model is the strategy that will be fixed before the code into the regular system of the final. Result is that the procedures and organizations around the user interface elements in the user interface elements of those moves, data storage, applications and functions of the code is used to indicate the way intertwined. In single-user system code structure can be so, because the system will not demand frequent changes. But for a large system such as large Web systems, or e-commerce systems to be applied. Model by incorporating data from a variety of access and control data can be separated to improve distributed system design. MVC design pattern is composed of three parts. Model is the application object, no user interface. Type in the screen showing that it represents the flow of data users. Controller user interface definition response to user input, the users responsible for the action against the Model into operation. Model View data updated to reflect the adoption of data changes.
2. MVC design pattern,
An MVC framework for the design of the system includes many models, but with MVC is most closely related to the following three models : Observer, Cambridge and Strategy.
2.1 Observer models
MVC through the use of purchase / notification form and the separation of the Model View. View to ensure that their content accurately reflected Model and state. Once Model content changes, there must be a mechanism to allow notification to the relevant Model View, View can be made relevant at the appropriate time updating of data. This design is also more general problems can be solved, the target separation, making a change to the target audience affect others, which targets those who do not know the details of the object being affected. This is described as Observer in the design model. Model type : Observer model is the object-oriented model, it is behaviour-based model. Model purposes : definition of hierarchical dependence relations between objects, or when a target value of the state change, all its dependent relationship with the object are notified and automatically updated. There are a variety of data may show a way, in different ways and may also show. When a way through a changed data, then the other should be able to show immediately that the data change and do accordingly.
Effect :
1. Abstract coupling. I only know that it has a target audience of some observers, the observers met each abstract Observer category simple interface, does not know their specific affiliation categories. This makes the coupling between goals and observers smallest and abstract.
2. Support radio communications. Needless to notify designated observers goals, how to deal with the observer informed decisions.
3. Possible accidents updated. We update logic, avoiding mistakes updated.
2.2 Faculty model
MVC is an important feature of View can nest. Nest can be used for any type of combination of local maps available, but also management of type nest. This thinking reflects the type and mix of components will be equal treatment design. This object-oriented design ideas in the area of Cambridge has been described as a design model. Model types : Cambridge model is the object-oriented model, it is also the structure type model. Model purpose : to target portfolio into tree structures to express "part-whole" level structure. Prepared for the use and combination of individual target audiences with the use of consistency.
Effect :
1. Definition of a target portfolio includes simple objects and the structure of the category level. Simple objects may be complex combinations of objects, and can be targeted portfolio mix. This customer-code used in the target areas can use simple combinations target.
2. Simplify customer-code. Needless to know their customers - a mix of target audiences is a simple target or can use these items in a consistent manner.
3. Easier to add new types of components. New components can easily be changed to a combination of customer-targeted codes.
2.3 Strategy model
Another important characteristic is the MVC can not change the View of changes View response to user input. This often requires a change in response to the logic of the system is very important. MVC to respond to the logic involved in the Controller. Controller of a category level structure could easily change to the original Controller appropriate, a new Controller. View Controller son used to achieve a specific example of such a response strategy. To achieve different response strategy, as long as examples of the use of different types of replacement will Controller. Also in the running time by changing the View Controller for users to change View of response strategies. This View-Controller relationship was described as an example of Strategy design pattern. Model types : Strategy model is the object-oriented model, it is behaviour-based model. Model purposes : definition of a series of algorithms, and their packaging, and ensure that they can replace each other, making algorithms can independently use its customer-change.
Effect :
1. Strategy category levels for Context definition of the relevant algorithms can be trusted or behaviour.
2. Alternative methods of succession. If the direct successor Context, with different acts will be added Context act, the realization of which would algorithm mixed up with Context, Context hard to preserve and expand, but can not dynamically changing algorithms. Will be enclosed in a separate Strategy category algorithms to enable algorithm independent Context change easily cut over expansion.
3. Can provide the same acts different date.
4. Strategy-must understand what customers between different.
5. Context and Strategy communications between costs.
6. An increase in the number of targets.
3. MVC in Web application system
Now some of the distributed systems such as Web-based B2B e-commerce system, suitable for use MVC framework. Through analysis from the perspective of high-level applications can be a target divided into three categories. Category is shown for the target audience consists of a group of commercial rules and data, there is a category that is receiving requests to control commercial target to complete the request. These applications often need to change is shown, such as web style, color, but also need to demonstrate the contents of the display. And the business rules and data to be relatively stable. Therefore, said that the frequent need to change the View objects that the business rules and data model to be relatively stable target, and that the control of the Controller is the most stable. When the system is usually issued after the View objects by artists, designers or HTML/JSP system managers to manage. Controller target applications development personnel from the development and implementation of rules for commercial and business development personnel from the target data, database managers and experts in the field of common completed. Show in Web?? or customers - control logic can be Servlet or JSP, dynamically generated Html. Generally used Servlet better than using JSP. JSP will be better with the Html code of separate codes for page designers and developers of separation efficiency. Servlet and JSP can complete all complete functions, actually JSP eventually converted into a Servlet. And control of the target system exists in every level, the coordination of cross-layer moves. Contain business rules and data objects exist in the EJB layer (EJB-centred model) or Web?? (Web-centred model).
3.1 View in the Web application system
View of the system shows that it fully exist in Web??. General by JSP, Java Bean and Custom Tag. JSP can generate dynamic web content using Java Custom Tag easier Bean, but it can show the logic of packaging, and more conducive to modular trusted. Some well-designed in a number of JSP Custom Tag can even be used in different system duplication. Model for control of JSP and Java Bean objects. JSP through Java Bean objects to retrieve the data model, the Model and Controller object is responsible for updating the data on Java Bean. In general, can we devise all possible screen that users can see all the elements of the system. Based on these elements, to identify the public part of passive components and dynamics. Can consider the use of templates means to separate the content generated JSP public, also need to change their generation Html or JSP from a JSP templates to dynamically introduce these different parts (include methods). Another issue to consider is screen option, when dealing with End users request template automatically available to show that the concern that users must know what is the screen components. So can consider all screens on the definition of a centralized document, such as a document or text document java. Taking into account the possibility of changes in future document definition screens, the best use of text documents such as a XML document, so future changes to the recompilation. According to the URL and user input parameters to shine upon the results of a screen, of course, likely to be made on the basis of the outcome of the implementation of actions to choose different results screen. Therefore, the need for a request for matching resources with document (XML), if a URL request several different results, it must specify in the document need to control the flow (a controller object), as well as the corresponding screen different flows.
3.2 Model in the Web application system
Model objects represent business rules and business data exist in EJB layer and Web??. In J2EE norms, the system needs some data stored in the database, such as user account information (account model), the company's data (company model), some not recorded in the database. If a user browsing the current catalogue (catalog model), the contents of his shopping (shopping cart model). Which one of these models exist in the data according to their life cycle and scope to decide. In Web?? a HttpSession and ServletContext and Java Bean objects to store data in the EJB layer is a data storage and logic EJB to. Web?? the Java Bean objects stored in the model layer model of the EJB object data copy. Because there are many different EJB tier model targets, so Web?? through a ModelManager to control the EJB layer object model in ModelManger background model can be used for packaging methods. In the EJB layer and the rules have all the data into EJB model is inappropriate. If the database can visit the Dao object model into objects. Dao can be encapsulated and the specific details of the database in the world, if we can write a different table, a number of databases, or even multiple databases. If the orders can be a model for OrderDAO, it may have to deal with Order table, table and OrderItemLines OrderStatus table. Value can also consider the use of targets. Value can be a target of securing long-range targets, because every time the remote object attributes could be a long-range redeployment process will consume network resources. EJB objects in the distance can be used instead target. In the distance, one-time items to be targeted instead of the value of all attributes.
3.3 Controller in Web application system
Coordination with the Model View Controller object to the request of users into the system to identify incidents. In Web?? generally a MainServlet (or Main.jsp), and receiving all requests, it can use screen flow management devices (ScreenFlowManger) decided next screen. There is a general request processors RequestProcessor contains all requests are needed to be done to deal with logic, such as the request translated into system events (RequestToEvent). Acting processors usually also includes a request for ClientControlWebImpl, it is logical to deal with the EJB layer in Web?? Acting. In EJB layer, a layer for EJB tier Web ClientController provide the CD visit. Another StateMachine used to create and delete ejb handle Web?? sent to the incident. Controller Another important function is synchronous View and Model data. ModelManger contained in a ModelUpdateManger, it puts events into a Model System assembly that all the needs of synchronous Model, and then notify Listeners do synchronous operation.
4. Concluding remarks
In recent years, with the Internet technology development and the emergence of new business models, the Web is based on a large number of applications. On how to design these systems architecture, and gradually there has been some convergence of opinion, the most important point is that its structure should be rational in the open. Demand than ever faster development of technology and design concepts, systems for the future, the cost of upgrading the smallest, research software systems architecture still very useful and necessary.

Bravo. And your point is?

Help translating a servlet code to bean

hi all
i'd like to translate a servlet code to bean code
the servlet, called from the <img src""> tag in my web page retrieves an images from a database and, setting the response content-type to "image" returns the image.
i'd like to do it through the common getXxx/setXxx methods of a bean
how to do it?
that's the servlet's code:
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, java.io.IOException {
        response.setContentType("text/html");
        ServletOutputStream out = response.getOutputStream();
        try
            Connection connection=(Connection)getServletContext().getAttribute("connection");
            Statement s=connection.createStatement();
            response.setContentType("image/jpeg");
            ResultSet rs=s.executeQuery("select "+request.getParameter("col")+" from products where id="+request.getParameter("id"));
            while(rs.next())
                out.write(rs.getBytes(request.getParameter("col")));
        catch(SQLException s)
            response.setContentType("text/html");
        catch(NullPointerException n)
        out.close();
    } thanx in advance
sandro

try this:
<%
response.setContentType("text/html");
try {
Connection connection=(Connection)application.getAttribute"connection");
   Statement s=connection.createStatement();
   response.setContentType("image/jpeg");
   ResultSet rs=s.executeQuery("select "+
              request.getParameter("col")+
             " from products where id="+
              request.getParameter("id"));
   while(rs.next()) {
%>
      <%= rs.getBytes(request.getParameter"col"))) %>
<%
} catch(SQLException s) {
   response.setContentType("text/html");
} catch(NullPointerException n) {
%>

Passing vectors into JSP from Servlet and passing data back to Servlet

I have been building an MVC application.
It has a controller which instantiates classes and evokes methods to
populate vectors. These vectors are then passed into a JSP. This part of the application works fine.
What I am having trouble with is a new JSP I have designed; this will
display the data that is actioned by the FORM action. This is actioned
based on the Search criteria entered by the user. Based on this a further vector is populated and brought back to the JSP as a vector
and this is rendered via the TABLE tag. Again this works fine.
Against each of the rows displayed, I have a print checkbox which can be checked by the user. On checking the records they want to print, they should then hint a Print button which should go back to the Servlet and print the data. THIS IS WHERE I HAVE THE PROBLEM. On going
back to the servlet the checkbox values are not displayed, rather
the values that initially populate the JSP. How do I get these new values back into the vector and hence accessible from the Servlet.
Any help with be very much appreciated.
Chris

Thanks for this.
Just to clarify I am not using Struts.
What I am having difficulties with is the fact that:
I can't get the checked values back to the Servlet - they keep the values they have in the bean - so as part of instantiating the bean class I set the value of the item to 'off'. The user will then check
the checkbox which should presumbably set the value to 'on'. This isn't happening because the setter method of the bean is not evoked again
because I don't come into this JSP again - the Servlet has finished here
and now needs to print the records. It can't do this because as
far as it is concerned nothing has changed since it last passed through
the vector to the JSP.
Even when I do the following:
Enumeration paramNames = request.getParameterNames();
String param = null;
while (paramNames.hasMoreElements())
param=(String)paramNames.nextElement();
System.out.println("parameter " + param + " is " +
request.getParameter(param));
what comes back is the valus of 'off' as opposed to 'on'.
The other thing is that 'request.getParameterNames()' only works
with the first record in the vector, i.e. it doesn't fetch any other
records that are rendered in the <TABLE> tag.
In desperation is there anybody out there who can help me.
Thanks
Chris
I am going to assume you are using a MVC framework
like Struts or very similar (I am assuming that from
the language you are using).
When the servlet passes the vector back to the JSP
page and you render the HTML that is passed back the
client your Vector is gone. The Vector is not
available at the HTML level that is being viewed at
the browser.
When the user selects the checkboxes and submits the
page (by clicking the print button) the controller
servlet (called ActionServlet in Struts, yours maybe
called something else) forwards the request to the
appropriate JavaBean and Servlet to process the
request. Either the JavaBean has to recreate the
Vector (not recommended) or the processing Servlet can
(better). You can do this by recreating the Vector
from scratch for the HttpRequest parameters or, at the
time of the initial request, saving Vector to a
session and then updating with the data you get back
from the client (again from the HttpRequest
parameters).
Either way you have to work with
HttpRequest.getParameter().

Servlets and Application Beans

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