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  • EJB 3 Session Bean Design for Simple CRUD

    - by sdoca
    I am writing an application that's sole purpose in life is to do CRUD operations for maintaining records in database. There are relationships between some of the tables/entities. Most examples I've seen for creating session beans deals with complex business logic/operations that interact with many entities which I don't have. Since my application is so very basic, what would be the best design for the session bean(s)? I was thinking of having one session bean per entity which had CRUD the methods defined. Then I thought of combining all of those session beans into a single session bean. And then I found this blog entry which is intriguing, but I must admit I don't understand all of it (what is a ServiceFacade?). I'm leaning towards session bean/entity class, but would like to hear more experienced opinions. Thanks.

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  • Video learning for database design

    - by donpal
    I'm trying to learn good relational database design (using mysql and php if that makes any difference). I've already done some database work, so I'm not totally clueless, but I suspect that my solutions may not have adhered to best practices for efficient searching, optimization, etc. Can someone suggest a good set of videos on the topic? If you know something is superb or has really made a difference in your own learning, please post your suggestion. Prefer videos, but books (as long as they're not too huge) are ok too. But prefer videos. Thank you

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  • C# ProgressBar design pattern

    - by MadSeb
    Hi, I'm working on a database upgrader application. The upgrader updates the schema of a database ( adds new columns, renames columns , adds new tables, new views to an existing database by executing SQL statements ). When a user wants to upgrade from version 1.0 to 2.0 , "Upgrader" objects are taken from an object factory and the "Execute" method of each "Upgrader" is called. The GUI of the application has a progress bar and each time an upgrader object performs a SQL statement the progress bar gets incremented. while (!version.Equal(CurrentVersion)) { IUpgrader myUpgrader = UpgraderFactory.GetUpgrader(version); myUpgrader.Execute(UpgradedFile,progressbar); version.Increment(); } My question is very simple : how should the upgrader object communicate with the progressbar. In the code above, the upgrader object is given direct access to the progressbar but I'm wondering if some better way of doing this or better design pattern exists. Regards, Seb

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  • Hotmail SMTP not working with javamail

    - by yashdosi
    I am trying to write a simple Java program to send emails from my hotmail account using JavaMail API. Here is my code : import java.util.Properties; import javax.mail.Message; import javax.mail.MessagingException; import javax.mail.PasswordAuthentication; import javax.mail.Session; import javax.mail.Transport; import javax.mail.internet.InternetAddress; import javax.mail.internet.MimeMessage; public class HotMailSend { public static void main(String args[]) { final String username = HOTMAIL.username; final String password = HOTMAIL.password; Properties props = new Properties(); props.setProperty("mail.smtp.auth", "true"); props.setProperty("mail.smtp.starttls.enable", "true"); props.setProperty("mail.smtp.host", "smtp.live.com"); props.setProperty("mail.smtp.port", "587"); Session session = Session.getInstance(props, new javax.mail.Authenticator() { protected PasswordAuthentication getPasswordAuthentication() { return new PasswordAuthentication(username, password); } }); try { Message message = new MimeMessage(session); message.setFrom(new InternetAddress(HOTMAIL.username)); message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(GMAIL.username)); message.setSubject("Testing Subject"); message.setText("Hey Buddy..!!!," + "\n\n No spam to my email, please!"); Transport.send(message); System.out.println("Done"); } catch (MessagingException e) { throw new RuntimeException(e); } } } And here is the error I am getting : Exception in thread "main" java.lang.RuntimeException: javax.mail.MessagingException: Can't send command to SMTP host; nested exception is: java.net.SocketException: Connection closed by remote host at HotMailSend.main(HotMailSend.java:45) Caused by: javax.mail.MessagingException: Can't send command to SMTP host; nested exception is: java.net.SocketException: Connection closed by remote host at com.sun.mail.smtp.SMTPTransport.sendCommand(SMTPTransport.java:2163) at com.sun.mail.smtp.SMTPTransport.sendCommand(SMTPTransport.java:2150) at com.sun.mail.smtp.SMTPTransport.close(SMTPTransport.java:1220) at javax.mail.Transport.send0(Transport.java:197) at javax.mail.Transport.send(Transport.java:124) at HotMailSend.main(HotMailSend.java:40) Caused by: java.net.SocketException: Connection closed by remote host at com.sun.net.ssl.internal.ssl.SSLSocketImpl.checkWrite(SSLSocketImpl.java:1307) at com.sun.net.ssl.internal.ssl.AppOutputStream.write(AppOutputStream.java:43) at com.sun.mail.util.TraceOutputStream.write(TraceOutputStream.java:114) at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65) at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:123) at com.sun.mail.smtp.SMTPTransport.sendCommand(SMTPTransport.java:2161) ... 5 more

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  • Is OO design's strength in semantics or encapsulation?

    - by Phil H
    Object-oriented design (OOD) combines data and its methods. This, as far as I can see, achieves two great things: it provides encapsulation (so I don't care what data there is, only how I get values I want) and semantics (it relates the data together with names, and its methods consistently use the data as originally intended). So where does OOD's strength lie? In constrast, functional programming attributes the richness to the verbs rather than the nouns, and so both encapsulation and semantics are provided by the methods rather than the data structures. I work with a system that is on the functional end of the spectrum, and continually long for the semantics and encapsulation of OO. But I can see that OO's encapsulation can be a barrier to flexible extension of an object. So at the moment, I can see the semantics as a greater strength. Or is encapsulation the key to all worthwhile code?

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  • Design view not working in Web Projects in Visual Studio 2008

    - by HenryHey
    When I try to edit an ASPX file with the Design View it freezes for a moment and does nothing, not even an error message. Looking through menus I've seen some strange things: If I go to Tools-Options-HTML Designer it gives me no options on the right panel, just a "Error loading property page" message. When I try to open a file using "Open With..." there should be something like "Web Form - Editor", but it is missing and I can only open them using Code View. I've tried repairing Visual Studio and reinstalling WebDesignerCore, but nothing works. Anyone had the same problem?

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  • Design - Where should objects be registered when using Windsor

    - by Fredrik Jansson
    I will have the following components in my application DataAccess DataAccess.Test Business Business.Test Application I was hoping to use Castle Windsor as IoC to glue the layers together but I am bit uncertain about the design of the gluing. My question is who should be responsible for registering the objects into Windsor? I have a couple of ideas; Each layer can register its own objects. To test the BL, the test bench could register mock classes for the DAL. Each layer can register the object of its dependencies, e.g. the business layer registers the components of the data access layer. To test the BL, the test bench would have to unload the "real" DAL object and register the mock objects. The application (or test app) registers all objects of the dependencies. Can someone help me with some ideas and pros/cons with the different paths? Links to example projects utilizing Castle Windsor in this way would be very helpful.

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  • derby + hibernate ConstraintViolationException using manytomany relationships

    - by user364470
    Hi, I'm new to Hibernate+Derby... I've seen this issue mentioned throughout the google, but have not seen a proper resolution. This following code works fine with mysql, but when I try this on derby i get exceptions: ( each Tag has two sets of files and vise-versa - manytomany) Tags.java @Entity @Table(name="TAGS") public class Tags implements Serializable { @Id @GeneratedValue(strategy=GenerationType.AUTO) public long getId() { return id; } @ManyToMany(targetEntity=Files.class ) @ForeignKey(name="USER_TAGS_FILES",inverseName="USER_FILES_TAGS") @JoinTable(name="USERTAGS_FILES", joinColumns=@JoinColumn(name="TAGS_ID"), inverseJoinColumns=@JoinColumn(name="FILES_ID")) public Set<data.Files> getUserFiles() { return userFiles; } @ManyToMany(mappedBy="autoTags", targetEntity=data.Files.class) public Set<data.Files> getAutoFiles() { return autoFiles; } Files.java @Entity @Table(name="FILES") public class Files implements Serializable { @Id @GeneratedValue(strategy=GenerationType.AUTO) public long getId() { return id; } @ManyToMany(mappedBy="userFiles", targetEntity=data.Tags.class) public Set getUserTags() { return userTags; } @ManyToMany(targetEntity=Tags.class ) @ForeignKey(name="AUTO_FILES_TAGS",inverseName="AUTO_TAGS_FILES") @JoinTable(name="AUTOTAGS_FILES", joinColumns=@JoinColumn(name="FILES_ID"), inverseJoinColumns=@JoinColumn(name="TAGS_ID")) public Set getAutoTags() { return autoTags; } I add some data to the DB, but when running over Derby these exception turn up (the don't using mysql) Exceptions SEVERE: DELETE on table 'FILES' caused a violation of foreign key constraint 'USER_FILES_TAGS' for key (3). The statement has been rolled back. Jun 10, 2010 9:49:52 AM org.hibernate.event.def.AbstractFlushingEventListener performExecutions SEVERE: Could not synchronize database state with session org.hibernate.exception.ConstraintViolationException: could not delete: [data.Files#3] at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:96) at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66) at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:2712) at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:2895) at org.hibernate.action.EntityDeleteAction.execute(EntityDeleteAction.java:97) at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:268) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:260) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:184) at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321) at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51) at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1206) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:613) at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:344) at $Proxy13.flush(Unknown Source) at data.HibernateORM.removeFile(HibernateORM.java:285) at data.DataImp.removeFile(DataImp.java:195) at booting.DemoBootForTestUntilTestClassesExist.main(DemoBootForTestUntilTestClassesExist.java:62) I have never used derby before so maybe there is something crutal that i'm missing 1) what am I doing wrong? 2) is there any way of cascading properly when I have 2 many-to-many relationships between two classes? Thanks!

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  • Best design for generating code from an AST?

    - by Sam Washburn
    I'm working on a pretty complex DSL that I want to compile down into a few high level languages. The whole process has been a learning experience. The compiler is written in java. I was wondering if anyone knew a best practice for the design of the code generator portion. I currently have everything parsed into an abstract syntax tree. I was thinking of using a template system, but I haven't researched that direction too far yet as I would like to hear some wisdom first from stack overflow. Thanks!

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  • Modeling software for network serialization protocol design

    - by Aurélien Vallée
    Hello, I am currently designing a low level network serialization protocol (in fact, a refinement of an existing protocol). As the work progress, pen and paper documents start to show their limits: i have tons of papers, new and outdated merged together, etc... And i can't show anything to anyone since i describe the protocol using my own notation (a mix of flow chart & C structures). I need a software that would help me to design a network protocol. I should be able to create structures, fields, their sizes, their layout, etc... and the software would generate some nice UMLish diagrams.

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  • ERD-CLASS design

    - by Mahesh
    Hello guyz,i am new to daatbase and class diagram.I just get scenarios from internet and try to develop ERD and Class Diagram for them.But the following scenario has caused me some problems, and i am not sure about my design. "Whenever an employee fills leave application form, the leave application should be appeared for approval to his/her team leader. Team Leader has the option to change the date of requested leave and to approve or reject the leave. Employee also has the option to change date of previously unapproved leaves or to cancel any of unapproved leave. In case of team leader, he can approve his own leaves. Management should be able to create categories of leaves like (Casual, Sick, Planned work, etc) and should be able to adjust the days allocated to each type of leave". I have identified these as entities for ERD 1) Employee(I think i dont need to make entity for Technical lead,since he is an employee) 2) LeaveHistory 3) LeaveCategory Plz correct me if the system need more classes or entities

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  • Class declaration bug

    - by aladine
    Please advise me what's wrong with this class declaration: ExchEngine.java package engine; public class ExchEngine { public ExchEngine() { } public static void main(String[] args) { ExchEngine engine=new ExchEngine() ; } } When I compile this file, I always get exception: java.lang.NoClassDefFoundError: test_engine/ExchEngine Caused by: java.lang.ClassNotFoundException: test_engine.ExchEngine at java.net.URLClassLoader$1.run(URLClassLoader.java:202) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:248) Exception in thread "main" This seems very weird that ExchEngine.java is inside a package and it cannot run itself. Thanks for any help.

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  • Mint Linux - Downgrade Java to 1.5

    - by Chrisc
    Hello, I posted this over at stack overflow, but had a suggestion to post it here for better help. Currently, I am running Mint Linux (Release 9). I need to downgrade Java from version 1.6 to 1.5, and have been trying to figure out how to go about this. So far, I've had no luck. The package manager doesn't seem to have it. Does anyone have any suggestions? Thanks, - Chris

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  • How to ACTUALLY install Java on Linux?

    - by Camran
    I have a Ubuntu Server. From the terminal, how should I install JDK? In this guide it says to use this command: sudo apt-get install sun-java6-bin sun-java6-jre sun-java6-jdk But on Suns website, it says JDK includes the JRE, so why the JRE in the line above? Anybody know how to actually install Java? Every guide and every forum shows different ways of doing it. BTW: It is a VPS (virtual private server) Thanks

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  • How to ACTUALLY install Java on Linux?

    - by Camran
    I have a Ubuntu Server. From the terminal, how should I install JDK? In this guide it says to use this command: sudo apt-get install sun-java6-bin sun-java6-jre sun-java6-jdk But on Suns website, it says JDK includes the JRE, so why the JRE in the line above? Anybody know how to actually install Java? Every guide and every forum shows different ways of doing it. BTW: It is a VPS (virtual private server) Thanks

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  • Adding controls dynamically at design time vb.net

    - by chris
    I have been developing some custom smart tags. I am using a DesignerActionMethodItem which gets me to a fired method in code. When I try to hit the controls.Add the control is added but it seems the designer is unaware of it. It is never serialized and it goes away when the form is refreshed in the designer. Any help would be greatly appreciated. I am sort of stuck and google hasn't helped me. Please don't send me anything about smart tags that has nothing to do with adding controls dynamically at design time, I have already read so many looking for this.

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  • Java appliction design question

    - by ring bearer
    Hi I have a hobby project, which is basically to maintain 'todo' tasks in the way I like. One task can be described as: public class TodoItem { private String subject; private Date dueBy; private Date startBy; private Priority priority; private String category; private Status status; private String notes; } as you can imagine I would have 1000 todo items at a given time. What is the best strategy to store a todo item? (currently on an XML file) such that all the items are loaded quickly up on app start up(the application shows kind of a dashboard of all the items at start up) What is the best way to design its back-end so that it can be ported to android/or a J2ME based phone Currently this is done using java swing. What should be the concerns so that it works efficiently on a device where memory is limited? Thanks!

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  • Dynamic table design (common lookup table), need a nice query to get the values

    - by Swoosh
    sql2005 This is my simplified example: (in reality there are 40+ tables in here, I only showed 2) I got a table called tb_modules, with 3 columns (id, description, tablename as varchar): 1, UserType, tb_usertype 2, Religion, tb_religion (Last column is actually the name of a different table) I got an other table that looks like this: tb_value (columns:id, tb_modules_ID, usertype_OR_religion_ID) values: 1111, 1, 45 1112, 1, 55 1113, 2, 123 1114, 2, 234 so, I mean 45, 55, 123, 234 are usertype OR religion ID's (45, 55 usertype, 123, 234 religion ID`s) Don't judge, I didn't design the database Question How can I make a select, showing * from tb_value, plus one column That one column would be TITLE from the tb_usertype or RELIGIONNAME from the tb_religion table I would like to make a general thing. Was thinking initially about maybe a SQL function that returns a string, but I think I would need dynamic SQL, which is not ok in a function. Anyone a better idea ?

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  • Database design: Using hundred of fields for little values

    - by user964260
    I'm planning to develop a PHP Web App, it will mainly be used by registered users(sessions) While thinking about the DB design, I was contemplating that in order to give the best user experience possible there would be lots of options for the user to activate, deactivate, specify, etc. For example: - Options for each layout elements, dialog boxes, dashboard, grid, etc. - color, size, stay visible, invisible, don't ask again, show everytime, advanced mode, simple mode, etc. This would get like 100s of fields ranging from simple Yes/No or 1 to N values..., for each user. So, is it having a field for each of these options the way to go? or how do those CRMs or CMS or other Web Apps do it to store lots of 1-2 char long values? Do they group them on Text fields separated by a special char and then "explode" them as an array for runtime usage? thank you

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  • HttpURLConnection getting locked

    - by Nayn
    Hi, I have a thread running under tomcat which creates a HttpUrlConnection and reads it through BufferedInputStream. After fetching data for some urls, it stalls. I got the jstack of the process which says HttpUrlConnection is locked and BufferedInputStream is also locked. "http-8080-1" daemon prio=10 tid=0x08683400 nid=0x79c9 runnable [0x8f618000] java.lang.Thread.State: RUNNABLE at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.io.BufferedInputStream.fill(BufferedInputStream.java:218) at java.io.BufferedInputStream.read1(BufferedInputStream.java:258) at java.io.BufferedInputStream.read(BufferedInputStream.java:317) - locked <0x956ef8c0> (a java.io.BufferedInputStream) at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:687) at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:632) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1072) - locked <0x956ef910> (a sun.net.www.protocol.http.HttpURLConnection) Could somebody help here. Thanks

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