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• Why is there no service-oriented language?

  - by Wolfgang

  Edit: To avoid further confusion: I am not talking about web services and such. I am talking about structuring applications internally, it's not about how computers communicate. It's about programming languages, compilers and how the imperative programming paradigm is extended. Original: In the imperative programming field, we saw two paradigms in the past 20 years (or more): object-oriented (OO), and service-oriented (SO) aka. component-based (CB). Both paradigms extend the imperative programming paradigm by introducing their own notion of modules. OO calls them objects (and classes) and lets them encapsulates both data (fields) and procedures (methods) together. SO, in contrast, separates data (records, beans, ...) from code (components, services). However, only OO has programming languages which natively support its paradigm: Smalltalk, C++, Java and all other JVM-compatibles, C# and all other .NET-compatibles, Python etc. SO has no such native language. It only comes into existence on top of procedural languages or OO languages: COM/DCOM (binary, C, C++), CORBA, EJB, Spring, Guice (all Java), ... These SO frameworks clearly suffer from the missing native language support of their concepts. They start using OO classes to represent services and records. This leads to designs where there is a clear distinction between classes that have methods only (services) and those that have fields only (records). Inheritance between services or records is then simulated by inheritance of classes. Technically, its not kept so strictly but in general programmers are adviced to make classes to play only one of the two roles. They use additional, external languages to represent the missing parts: IDL's, XML configurations, Annotations in Java code, or even embedded DSL like in Guice. This is especially needed, but not limited to, since the composition of services is not part of the service code itself. In OO, objects create other objects so there is no need for such facilities but for SO there is because services don't instantiate or configure other services. They establish an inner-platform effect on top of OO (early EJB, CORBA) where the programmer has to write all the code that is needed to "drive" SO. Classes represent only a part of the nature of a service and lots of classes have to be written to form a service together. All that boiler plate is necessary because there is no SO compiler which would do it for the programmer. This is just like some people did it in C for OO when there was no C++. You just pass the record which holds the data of the object as a first parameter to the procedure which is the method. In a OO language this parameter is implicit and the compiler produces all the code that we need for virtual functions etc. For SO, this is clearly missing. Especially the newer frameworks extensively use AOP or introspection to add the missing parts to a OO language. This doesn't bring the necessary language expressiveness but avoids the boiler platform code described in the previous point. Some frameworks use code generation to produce the boiler plate code. Configuration files in XML or annotations in OO code is the source of information for this. Not all of the phenomena that I mentioned above can be attributed to SO but I hope it clearly shows that there is a need for a SO language. Since this paradigm is so popular: why isn't there one? Or maybe there are some academic ones but at least the industry doesn't use one.

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• Hibernate: "Field 'id' doesn't have a default value"

  - by André Neves

  Hi, all. I'm facing what I think is a simple problem with Hibernate, but can't get over it (Hibernate forums being unreachable certainly doesn't help). I have a simple class I'd like to persist, but keep getting: SEVERE: Field 'id' doesn't have a default value Exception in thread "main" org.hibernate.exception.GenericJDBCException: could not insert: [hibtest.model.Mensagem] at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:103) at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:91) [ a bunch more ] Caused by: java.sql.SQLException: Field 'id' doesn't have a default value [ a bunch more ] The relevant code for the persisted class is: package hibtest.model; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.Inheritance; import javax.persistence.InheritanceType; @Entity @Inheritance(strategy = InheritanceType.JOINED) public class Mensagem { protected Long id; protected Mensagem() { } @Id @GeneratedValue public Long getId() { return id; } public Mensagem setId(Long id) { this.id = id; return this; } } And the actual running code is just plain: SessionFactory factory = new AnnotationConfiguration() .configure() .buildSessionFactory(); { Session session = factory.openSession(); Transaction tx = session.beginTransaction(); Mensagem msg = new Mensagem("YARR!"); session.save(msg); tx.commit(); session.close(); } I tried some "strategies" within the GeneratedValue annotation but it just doesn't seem to work. Initializing id doesn't help either! (eg Long id = 20L). Could anyone shed some light? EDIT 2: confirmed: messing with@GeneratedValue(strategy = GenerationType.XXX) doesn't solve it SOLVED: recreating the database solved the problem

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• Is it okay to implement reference counting through composition?

  - by Billy ONeal

  Most common re-usable reference counted objects use private inheritance to implement re-use. I'm not a huge fan of private inheritance, and I'm curious if this is an acceptable way of handling things: class ReferenceCounter { std::size_t * referenceCount; public: ReferenceCounter() : referenceCount(NULL) {}; ReferenceCounter(ReferenceCounter& other) : referenceCount(other.referenceCount) { if (!referenceCount) { referenceCount = new std::size_t(1); other.referenceCount = referenceCount; } else { ++(*referenceCount); } }; ReferenceCounter& operator=(const ReferenceCounter& other) { ReferenceCounter temp(other); swap(temp); return *this; }; void swap(ReferenceCounter& other) { std::swap(referenceCount, other.referenceCount); }; ~ReferenceCounter() { if (referenceCount) { --(*referenceCount); if (!*referenceCount) delete referenceCount; } }; operator bool() const { return referenceCount && (*referenceCount != 0); }; }; class SomeClientClass { HANDLE someHandleThingy; ReferenceCounter objectsStillActive; public: SomeClientClass() { //Construct handle thingy } ~SomeClientClass() { if (objectsStillActive) return; //Release resources }; }; or are there subtle problems with this I'm not seeing?

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• ASP.NET MVC UpdateModel doesn't update inherited public properties??

  - by mrjoltcola

  I refactored some common properties into a base class and immediately my model updates started failing. UpdateModel() and TryUpdateModel() do not seem to update inherited public properties. I cannot find detailed info on MSDN nor Google as to the rules or semantics of these methods. The docs are terse (http://msdn.microsoft.com/en-us/library/dd470933.aspx), simply stating: Updates the specified model instance using values from the controller's current value provider. Well that leads us to believe it is as simple as that. It makes no mention of limitations with inheritance. My assumption is the methods are reflecting on the top class only, ignoring base properties, but this seems to be an ugly shortcoming, if so. SOLVED: Eep, this turned out to have nothing to do with inheritance. My base class was implemented with public fields, not properties. Switching them to formal properties (adding {get; set; }) was all I needed. This has bitten me before, I keep wanting to use simple, public fields.

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• Runtime Exception when using Custom Healthmonitoring event in medium trust

  - by Elementenfresser

  Hi, I'm using custom healthmonitoring events in ASP.NET We recently moved to a new server with default High Trust Permissions. Literature says that healthmonitoring and custom events should work under Medium or higher trust (http://msdn.microsoft.com/en-us/library/bb398933.aspx). Problem is it doesn't. In less than high trust I get a SecurityException saying The application attempted to perform an operation not allowed by the security policy It works in Full trust or when I remove the inheritance of System.Web.Management.WebErrorEvent. Any suggestions anyone? Here is the super simple code behind with a custom event defined: public partial class Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { try { CallCustomEvent(); } catch (Exception ex) { Response.Write(ex.Message); throw ex; } } /// <summary> /// this metho is never called due to lacking permissions... /// </summary> private void CallCustomEvent() { try { //do something useful here } catch (Exception) { //code to instantiate the forbidden inheritance... WebBaseEvent.Raise(new CustomEvent()); } } } /// <summary> /// custom error inheriting WebErrorEvent which is not allowed in high trust? can't believe that... /// </summary> public class CustomEvent : WebErrorEvent { public CustomEvent() : base("test", HttpContext.Current.Request, 100001, new ApplicationException("dummy")) { } } and the Web Config excerpt for high trust: <system.web> <trust level="High" originUrl="" />

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• C#'s equivalent to VB.Net's DirectCast?

  - by Collin Sauve

  This has probably been asked before, but if it has, I can't find it. Does C# have an equivalent to VB.Net's DirectCast? I am aware that it has () casts and the 'as' keyword, but those line up to CType and TryCast. To be clear, these keywords do the following; CType/() casts: If it is already the correct type, cast it, otherwise look for a type converter and invoke it. If no type converter is found, throw an InvalidCastException. TryCast/"as" keyword: If it is the correct type, cast it, otherwise return null. DirectCast: If it is the correct type, cast it, otherwise throw an InvalidCastException. EDIT: After I have spelled out the above, some people have still responded that () is equivalent, so I will expand further upon why this is not true. DirectCast only allows for either Narrowing or Widening conversions on inheritance tree, it does not support conversions across different branches like () does. ie: C#, this compiles and runs: //This code uses a type converter to go across an inheritance tree double d = 10; int i = (int)d; VB.Net, this does NOT COMPILE 'Direct cast can only go up or down a branch, never across to a different one. Dim d as Double= 10 Dim i as Integer = DirectCast(d, Integer) The equivalent in VB.Net to my C# code is CType: 'This compiles and runs Dim d as Double= 10 Dim i as Integer = CType(d, Integer) (Edit again, I was originally using strings, I changed it to double... sorry)

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• Interface vs Abstract Class (general OO)

  - by Kave

  Hi, I have had recently two telephone interviews where I've been asked about the differences between an Interface and an Abstract class. I have explained every aspect of them I could think of, but it seems they are waiting for me to mention something specific, and I dont know what it is. From my experience I think the following is true, if i am missing a major point please let me know: Interface: Every single Method declared in an Interface will have to be implemented in the subclass. Only Events, Delegates, Properties (C#) and Methods can exist in a Interface. A class can implement multiple Interfaces. Abstract Class Only Abstract methods have to be implemented by the subclass. An Abstract class can have normal methods with implementations. Abstract class can also have class variables beside Events, Delegates, Properties and Methods. A class can only implement one abstract class only due non-existence of Multi-inheritance in C#. 1) After all that the interviewer came up with the question What if you had an Abstract class with only abstract methods, how would that be different from an interface? I didnt know the answer but I think its the inheritance as mentioned above right? 2) An another interviewer asked me what if you had a Public variable inside the interface, how would that be different than in Abstract Class? I insisted you can't have a public variable inside an interface. I didn't know what he wanted to hear but he wasn't satisfied either. Many Thanks for clarification, Kave See Also: When to use an interface instead of an abstract class and vice versa Interfaces vs. Abstract Classes How do you decide between using an Abstract Class and an Interface?

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• Hibernate: Querying objects by attributes of inherited classes

  - by MichaelD

  Hi all, I ran into a problem with Hibernate concerning queries on classes which use inheritance. Basically I've the following class hierarchy: @Entity @Table( name = "recording" ) class Recording { ClassA attributeSet; ... } @Entity @Inheritance( strategy = InheritanceType.JOINED ) @Table( name = "classA" ) public class ClassA { String Id; ... } @Entity @Table( name = "ClassB1" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB1 extends ClassA { private Double P1300; private Double P2000; } @Entity @Table( name = "ClassB2" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB2 extends ClassA { private Double P1300; private Double P3000; } The hierarchy is already given like this and I cannot change it easily. As you can see ClassB1 and ClassB2 inherit from ClassA. Both classes contain a set of attributes which sometimes even have the same names (but I can't move them to ClassA since there are possible more sub-classes which do not use them). The Recording class references one instance of one of this classes. Now my question: What I want to do is selecting all Recording objects in my database which refer to an instance of either ClassB1 or ClassB2 with e.g. the field P1300 == 15.5 (so this could be ClassB1 or ClassB2 instances since the P1300 attribute is declared in both classes). What I tried is something like this: Criteria criteria = session.createCriteria(Recording.class); criteria.add( Restrictions.eq( "attributeSet.P1300", new Double(15.5) ) ); criteria.list(); But since P1300 is not an attribute of ClassA hibernate throws an exception telling me: could not resolve property: P1300 of: ClassA How can I tell hibernate that it should search in all subclasses to find the attribute I want to filter? Thanks MichaelD

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• Security Exception when using Custom ASP.NET Healthmonitoring event in medium trust

  - by Elementenfresser

  Hi, I'm using custom healthmonitoring events in ASP.NET We recently moved to a new server with default High Trust Permissions. Literature says that healthmonitoring and custom events should work under Medium or higher trust (http://msdn.microsoft.com/en-us/library/bb398933.aspx). Problem is - it doesn't. In less than full trust I get a SecurityException saying The application attempted to perform an operation not allowed by the security policy It works in Full trust or when I remove the inheritance of System.Web.Management.WebErrorEvent. Any suggestions anyone? Here is the super simple code behind with a custom event defined: public partial class Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { try { CallCustomEvent(); } catch (Exception ex) { Response.Write(ex.Message); throw ex; } } /// <summary> /// this metho is never called due to lacking permissions... /// </summary> private void CallCustomEvent() { try { //do something useful here } catch (Exception) { //code to instantiate the forbidden inheritance... WebBaseEvent.Raise(new CustomEvent()); } } } /// <summary> /// custom error inheriting WebErrorEvent which is not allowed in high trust? can't believe that... /// </summary> public class CustomEvent : WebErrorEvent { public CustomEvent() : base("test", HttpContext.Current.Request, 100001, new ApplicationException("dummy")) { } } and the Web Config excerpt for high trust: <system.web> <trust level="High" originUrl="" />

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• How To Create a Flexible Plug-In Architecture?

  - by justkt

  A repeating theme in my development work has been the use of or creation of an in-house plug-in architecture. I've seen it approached many ways - configuration files (XML, .conf, and so on), inheritance frameworks, database information, libraries, and others. In my experience: A database isn't a great place to store your configuration information, especially co-mingled with data Attempting this with an inheritance hierarchy requires knowledge about the plug-ins to be coded in, meaning the plug-in architecture isn't all that dynamic Configuration files work well for providing simple information, but can't handle more complex behaviors Libraries seem to work well, but the one-way dependencies have to be carefully created. As I seek to learn from the various architectures I've worked with, I'm also looking to the community for suggestions. How have you implemented a solid plug-in architecture? What was your worst failure (or the worst failure you've seen)? What would you do if you were going to implement a new plug-in architecture? What SDK or open source project that you've worked with has the best example of a good architecture? A few examples I've been finding on my own: Perl's Module::Plugable An SO question with a list for Java (including Sever Provider Interfaces) An SO question for C++ pointing to a Dr. Dobbs article These examples seem to play to various language strengths. Is a good plugin architecture necessarily tied to the language? Is it best to use tools to create a plugin architecture, or to do it on one's own following models?

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• Componentizing complex functionality in an MVC web app

  - by NXT

  Hi Everyone, This is question about MVC web-app architecture, and how it can be extended to handle componentizing moderately complex units of functionality. I have an MVC style web-app with a customer facing credit card charge page. I've been asked to allow the admins to enter credit card payments as well, for times when credit cards are taken over the phone. The customer facing credit card charge section of the website is currently it's own controller, with approximately 3 pages and a login. That controller is responsible for: Customer login credential authentication Credit card data collection Calling a library to do the actual charge. reporting the results to the user. I would like to extract the card data collection pages into a component of some kind so that I can easily reuse the code on the admin side of the app. Right now my components are limited to single "view" pages with PHP style embedded Perl code. This is a simple, custom MVC framework written in Perl. Right now, controllers are called directly from the framework to service web requests. My idea is to allow controllers to be called from other controllers, so that I can componentize more complex functionality. For simplicity I think I prefer composition over inheritance, even though it will require writing a bunch of pass-through methods (actions). Being Perl, I could in theory do multiple inheritance. I'm wondering if anyone with experience in other MVC web frameworks can comment on how this sort of thing is usually done. Thank you.

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• Java downcasting dilemma

  - by Shades88

  please have a look at this code here. class Vehicle { public void printSound() { System.out.print("vehicle"); } } class Car extends Vehicle { public void printSound() { System.out.print("car"); } } class Bike extends Vehicle{ public void printSound() { System.out.print("bike"); } } public class Test { public static void main(String[] args) { Vehicle v = new Car(); Bike b = (Bike)v; v.printSound(); b.printSound(); Object myObj = new String[]{"one", "two", "three"}; for (String s : (String[])myObj) System.out.print(s + "."); } } Executing this code will give ClassCastException saying inheritance.Car cannot be cast to inheritance.Bike. Now look at the line Object myObj = new String[]{"one", "two", "three"};. This line is same as Vehicle v = new Car(); right? In both lines we are assigning sub class object to super class reference variable. But downcasting String[]myObj is allowed but (Bike)v is not. Please help me understand what is going on around here.

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• Database schema for Product Properties

  - by Chemosh

  As so many people I'm looking for a Products /Product Properties database schema. I'm using Ruby on Rails and (Thinking) Sphinx for faceted searches. Requirements: Adding new product types and their options should not require a change to the database schema Support faceted searches using Sphinx. Solutions I've come across: (See Bill Karwin's answer) Option 1: Single Table Inheritance Not an option really. The table would contain way to many columns. Option 2: Class Table Inheritance Ruby on Rails caches the database schema on start-up which means a restart whenever a new type of product is introduced. If you have a size able product catalog this could mean hundreds of tables. Option 3: Serialized LOB Kills being able to do faceted searches without heavy application logic. Option 4: Entity-Attribute-Value For testing purposes, EAV worked fine. However it could quickly become a mess and a maintenance hell as you add more and more options (e.g. when an option increase the prices or delivery time). What option should I go with? What other solutions are out there? Is there a silver bullet (ha) I overlooked?

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• How do I DRY up business logic between sever-side Ruby and client-side Javascript?

  - by James A. Rosen

  I have a Widget model with inheritance (I'm using Single-Table Inheritance, but it's equally valid for Class-per-Table). Some of the subclasses require a particular field; others do not. class Widget < ActiveRecord ALL_WIDGET_TYPES = [FooWidget, BarWidget, BazWidget] end class FooWidget < Widget validates_presence_of :color end class BarWidget < Widget # no color field end class BazWidget < Widget validates_presence_of :color end I'm building a "New Widget" form (app/views/widgets/new.html.erb) and would like to dynamically show/hide the color field based on a <select> for widget_type. <% form_for @widget do |f| %> <%= f.select :type, Widget::ALL_WIDGET_TYPES %> <div class='hiddenUnlessWidgetTypeIsFooOrBaz'> <%= f.label :color %> <%= f.text_field :color %> </div> <% end %> I can easily write some jQuery to watch for onChange events on widget_type, but that would mean putting some sort of WidgetTypesThatRequireColor constant in my Javascript. Easy enough to do manually, but it is likely to get disconnected from the Widget model classes. I would prefer not to output Javascript directly in my view, though I have considered using content_for(:js) and have a yield :js in my template footer. Any better ideas?

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• Link compatibility between C++ and D

  - by Caspin

  D easily interfaces with C. D just as easily interfaces with C++, but (and it's a big but) the C++ needs to be extremely trivial. The code cannot use: namespaces templates multiple inheritance mix virtual with non-virtual methods more? I completely understand the inheritance restriction. The rest however, feel like artificial limitations. Now I don't want to be able to use std::vector<T> directly, but I would really like to be able to link with std::vector<int> as an externed template. The C++ interfacing page has this particularly depressing comment. D templates have little in common with C++ templates, and it is very unlikely that any sort of reasonable method could be found to express C++ templates in a link-compatible way with D. This means that the C++ STL, and C++ Boost, likely will never be accessible from D. Admittedly I'll probably never need std::vector while coding in D, but I'd love to use QT or boost. So what's the deal. Why is it so hard to express non-trivial C++ classes in D? Would it not be worth it to add some special annotations or something to express at least namespaces?

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• How to understand other people's CSS architectures?

  - by John

  I am reasonably good with CSS. However, when working with someone else's CSS, it's difficult for me to see the "bigger picture" in their architecture (but i have no problem when working with a CSS sheet I wrote myself). For example, I have no problems using Firebug to isolate and fix cross browser compatibility issues, or fixing a floating issue, or changing the height on a particular element. But if I'm asked to do something drastic such as, "I want the right sidebars of pages A, B, C and D to have a red border. I want the right side bars of pages E, F and G to have a blue border if and only if the user mouses over", then it takes me time a long time to map out all the CSS inheritance rules to see the "bigger picture". For some reason, I don't encounter the same difficulty with backend code. After a quick debriefing of how a feature works, and a quick inspection of the controller and model code, I will feel comfortable with the architecture. I will think, "it's reasonable to assume that there will be an Employee class that inherits from the Person Class that's used by a Department controller". If I discover inconvenient details that aren't consistent with overall architectural style, I am confident that I can hammer things back in place. With someone else's CSS work, it's much harder for me to see the "relationships" between different classes, and when and how the classes are used. When there are many inheritance rules, I feel overwhelmed. I'm having trouble articulating my question and issues... All I want to know is, why is it so much harder for me to see the bigger picture in someone else's CSS architecture than compared to someone else's business logic layer? **Does it have any thing to do with CSS being a relatively new technology, and there aren't many popular design patterns?

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• Javascript OOP - accessing the inherited property or function from a closure within a subclass

  - by Ali

  Hi All, I am using the javascript inheritance helper provided here: http://ejohn.org/blog/simple-javascript-inheritance/ I have the following code, and I have problem accessing the inherited property or function from a closure within a subclass as illustrated below. I am new to OOP javascript code and I appreciate your advice. I suppose within the closure, the context changes to JQuery (this variable) hence the problem. I appreciate your comments. Thanks, -A PS - Using JQuery 1.5 var Users = Class.extend({ init: function(names){this.names = names;} }); var HomeUsers = Users.extend({ work:function(){ // alert(this.names.length); // PRINTS A // var names = this.names; // If I make a local alias it works $.map([1,2,3],function(){ var newName = this.names.length; //error this.names is not defined. alert(newName); }); } }); var users = new HomeUsers(["A"]); users.work();

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• What are incentives (if any) to use WinRT instead of .Net?

  - by Ark-kun

  Let's compare WinRT with .Net .Net .Net is the 13+ years evolution of COM. Three main parts of .Net are execution environment, standard libraries and supported languages. CLR is the native-code execution environment based on COM .Net Framework has a big set of standard libraries (implemented using managed and native code) that can be used from all .Net languages. There are .Net classes that allow using OS APIs. WPF or Silverlight provide a XAML-based UI framework .Net can be used with C++, C#, Javascript, Python, Ruby, VB, LISP, Scheme and many other languages. C++/.Net is a variation of the C++ language that allows interaction with .Net objects. .Net supports inheritance, generics, operator and method overloading and many other features. .Net allows creating apps that run on Windows (XP, 7, 8 Pro (Desktop and Metro), RT, CE, etc), Mac OS, Linux (+ other *nix); iOS, Android, Windows Phone (7, 8); Internet Explorer, Chrome, Firefox; XBox 360, Playstation Suite; raw microprocessors. There is support for creating games (2D/3D) using any managed language or C++. Created by Developer Division WinRT WinRT is based on COM. Three main parts of WinRT are execution environment, standard libraries and supported languages. WinRT has a native-code execution environment based on COM WinRT has a set of standard libraries that more or less can be used from WinRT languages. There are WinRT classes that allow using OS APIs. Unnamed Silverlight clone provides a XAML-based UI framework WinRT can be used with C++, C#, Javascript, VB. C++/CX is a variation of the C++ language that allows interaction with WinRT objects. Custom WinRT components don't support inheritance (classes must be sealed), generics, operator overloading and many other features. WinRT allows creating apps that run on Windows 8 Pro and RT (Metro only); Windows Phone 8 (limited). There is support for creating games (2D/3D) using C++ only. Ordered by Windows Team I think that all the aspects except the last ones are very important for developers. On the other hand it seems that the most important aspect for Microsoft is the last one. So, given the above comparison of conceptually identical technologies, what are incentives (if any) to use WinRT instead of .Net?

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• Try and catch error trapping. why is it so significant

  - by oded

  sorry if it sounds dumb ' as i am i a process of learnning java i try to understand , why on earth i should "try" a method to catch errors. it looks to me like the concept is:- ' letting a process run assuming its not properly developed. should i always assume that a program based on classes and inheritance is bound for unexpected errors, which i should handle with such a heavy tools like try catch throw throws ? should all java programs be included withing try catch framework? Thanks Oded.

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• Book Review: Oracle ADF Real World Developer’s Guide

  - by Frank Nimphius

  Recently PACKT Publishing published "Oracle ADF Real World Developer’s Guide" by Jobinesh Purushothaman, a product manager in our team. Though already the sixth book dedicated to Oracle ADF, it has a lot of great information in it that none of the previous books covered, making it a safe buy even for those who own the other books published by Oracle Press (McGrwHill) and PACKT Publishing. More than the half of the "Oracle ADF Real World Developer’s Guide" book is dedicated to Oracle ADF Business Components in a depth and clarity that allows you to feel the expertise that Jobinesh gained in this area. If you enjoy Jobinesh blog (http://jobinesh.blogspot.co.uk/) about Oracle ADF, then, no matter what expert you are in Oracle ADF, this book makes you happy as it provides you with detail information you always wished to have. If you are new to Oracle ADF, then this book alone doesn't get you flying, but, if you have some Java background, accelerates your learning big, big, big times. Chapter 1 is an introduction to Oracle ADF and not only explains the layers but also how it compares to plain Java EE solutions (page 13). If you are new to Oracle JDeveloper and ADF, then at the end of this chapter you know how to start JDeveloper and begin your ADF development Chapter 2 starts with what Jobinesh really is good at: ADF Business Components. In this chapter you learn about the architecture ingredients of ADF Business Components: View Objects, View Links, Associations, Entities, Row Sets, Query Collections and Application Modules. This chapter also provides a introduction to ADFBC SDO services, as well as sequence diagrams for what happens when you execute queries or commit updates. Chapter 3 is dedicated to entity objects and  is one of many chapters in this book you will enjoy and never want to miss. Jobinesh explains the artifacts that make up an entity object, how to work with entities and resource bundles, and many advanced topics, including inheritance, change history tracking, custom properties, validation and cursor handling.  Chapter 4 - you guessed it - is all about View objects. Comparable to entities, you learn about the XM files and classes that make a view object, as well as how to define and work with queries. List-of-values, inheritance, polymorphism, bind variables and data filtering are interesting - and important topics that follow. Again the chapter provides helpful sequence diagrams for you to understand what happens internally within a view object. Chapter 5 focuses on advanced view object and entity object topics, like lifecycle callback methods and when you want to override them. This chapter is a good digest of Jobinesh's blog entries (which most ADF developers have in their bookmark list). Really worth reading ! Chapter 6 then is bout Application Modules. Beside of what application modules are, this chapter covers important topics like properties, passivation, activation, application module pooling, how and where to write custom logic. In addition you learn about the AM lifecycle and request sequence. Chapter 7 is about the ADF binding layer. If you are new to Oracle ADF and got lost in the more advanced ADF Business Components chapters, then this chapter is where you get back into the game. In very easy terms, Jobinesh explains what the ADF binding is, how it fits into the JSF request lifecycle and what are the metadata file involved. Chapter 8 then goes into building data bound web user interfaces. In this chapter you get the basics of JavaServer Faces (e.g. managed beans) and learn about the interaction between the JSF UI and the ADF binding layer. Later this chapter provides advanced solutions for working with tree components and list of values. Chapter 9 introduces bounded task flows and ADF controller. This is a chapter you want to read if you are new to ADF of have started. Experts don't find anything new here, which doesn't mean that it is not worth reading it (I for example, enjoyed the controller talk very much) Chapter 10 is an advanced coverage of bounded task flow and talks about contextual events  Chapter 11 is another highlight and explains error handling, trains, transactions and more. I can only recommend you read this chapter. I am aware of many documents that cover exception handling in Oracle ADF (and my Oracle Magazine article for January/February 2013 does the same), but none that covers it in such a great depth. Chapter 12 covers ADF best practices, which is a great round-up of all the tips provided in this book (without Jobinesh to repeat himself). Its all cool stuff that helps you with your ADF projects. In summary, "Oracle ADF Real World Developer’s Guide" by Jobinesh Purushothaman is a great book and addition for all Oracle ADF developers and those who want to become one. Frank

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• Can my ikmnet test results say something about career choice I should take?

  - by Nicke

  I took 2 tests via ikmnet and scored 70 % on SQL and 65 % on Java. While not bad, it can be improved. The subskills I need to improve according to the test are interfaces and inheritance, compilation and deployment, flow control, The java.lang package and "Java Program Construction" and these topics seems rather broad to me. Rather than just learning by programming, could you advice me to take a certification, follow a course or otherwise improve my skills? By the way, I enjoy python more than Java so should I market myself more of a python programmer or even a role that some companies search for which seems like a system developer with more technical writing where the title is system analysts (evaluating systems in cooperation with management rather than programming.) Thank you for any comment and/or answer.

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• Writing C# Code Using SOLID Principles

  - by bipinjoshi

  Most of the modern programming languages including C# support objected oriented programming. Features such as encapsulation, inheritance, overloading and polymorphism are code level features. Using these features is just one part of the story. Equally important is to apply some object oriented design principles while writing your C# code. SOLID principles is a set of five such principles--namely Single Responsibility Principle, Open/Closed Principle, Liskov Substitution Principle, Interface Segregation Principle and Dependency Inversion Principle. Applying these time proven principles make your code structured, neat and easy to maintain. This article discusses SOLID principles and also illustrates how they can be applied to your C# code.http://www.binaryintellect.net/articles/7f857089-68f5-4d76-a3b7-57b898b6f4a8.aspx 

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• ETPM/OUAF 2.3.1 Framework Overview - Session 2

  - by Rick Finley

  A number of sessions are planned to review the ETPM (OUAF) 2.3.1 Framework.  These sessions will include an overview of the Navigation, Portals, Zones, Business Objects, Business Services, Algorithms, Scripts, etc.. Session 2 includes a more in depth discusion of Business Objects (BO).  Session 2 specifically covers BO Schema, BO Options, and BO inheritance in more depth.  Click on the link below for Session 2 (52 minutes). To stream the recording:   https://oracletalk.webex.com/oracletalk/ldr.php?AT=pb&SP=MC&rID=70624122&rKey=8a16e59ed3736f1c To download the recording: https://oracletalk.webex.com/oracletalk/lsr.php?AT=dw&SP=MC&rID=70624122&rKey=140a83f63b8fa22a For additional questions, please contact [email protected].

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• What real life bad habits has programming given you?

  - by Jacob T. Nielsen

  Programming has given me a lot of bad habits and it continues to give me more everyday. But I have also gotten some bad habits from the mindset that I have put myself in. There simply are some things that are deeply rooted in my nature, though some of them I wish I could get rid of. A few: Looking for polymorphism, inheritance and patterns in all of God's creations. Explaining the size of something in pixels and colors in hex code. Using code related abstract terms in everyday conversations. How have you been damaged?

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• Are CK Metrics still considered useful? Is there an open source tool to help?

  - by DeveloperDon

  Chidamber & Kemerer proposed several metrics for object oriented code. Among them, depth of inheritance tree, weighted number of methods, number of member functions, number of children, and coupling between objects. Using a base of code, they tried to correlated these metrics to the defect density and maintenance effort using covariant analysis. Are these metrics actionable in projects? Perhaps they can guide refactoring. For example weighted number of methods might show which God classes needed to be broken into more cohesive classes that address a single concern. Is there approach superseded by a better method, and is there a tool that can identify problem code, particularly in moderately large project being handed off to a new developer or team?

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