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• How can I improve this design?

  - by klausbyskov

  Let's assume that our system can perform actions, and that an action requires some parameters to do its work. I have defined the following base class for all actions (simplified for your reading pleasure): public abstract class BaseBusinessAction<TActionParameters> : where TActionParameters : IActionParameters { protected BaseBusinessAction(TActionParameters actionParameters) { if (actionParameters == null) throw new ArgumentNullException("actionParameters"); this.Parameters = actionParameters; if (!ParametersAreValid()) throw new ArgumentException("Valid parameters must be supplied", "actionParameters"); } protected TActionParameters Parameters { get; private set; } protected abstract bool ParametersAreValid(); public void CommonMethod() { ... } } Only a concrete implementation of BaseBusinessAction knows how to validate that the parameters passed to it are valid, and therefore the ParametersAreValid is an abstract function. However, I want the base class constructor to enforce that the parameters passed are always valid, so I've added a call to ParametersAreValid to the constructor and I throw an exception when the function returns false. So far so good, right? Well, no. Code analysis is telling me to "not call overridable methods in constructors" which actually makes a lot of sense because when the base class's constructor is called the child class's constructor has not yet been called, and therefore the ParametersAreValid method may not have access to some critical member variable that the child class's constructor would set. So the question is this: How do I improve this design? Do I add a Func<bool, TActionParameters> parameter to the base class constructor? If I did: public class MyAction<MyParameters> { public MyAction(MyParameters actionParameters, bool something) : base(actionParameters, ValidateIt) { this.something = something; } private bool something; public static bool ValidateIt() { return something; } } This would work because ValidateIt is static, but I don't know... Is there a better way? Comments are very welcome.

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• Factory Method Pattern clarification

  - by nettguy

  My understanding of Factory Method Pattern is (Correct me if i am wrong) Factory Method Pattern "Factory Method allow the client to delegates the product creation (Instance Creation) to the subclass". There are two situation in which we can go for creating Factory Method pattern. (i) When the client is restricted to the product (Instance) creation. (ii) There are multiple products available.But a decision to be made which product instance need to be returned. If you want to create Abstract Method pattern You need to have abstract product Concrete Product Factory Method to return the appropriate product. Example : public enum ORMChoice { L2SQL, EFM, LS, Sonic } //Abstract Product public interface IProduct { void ProductTaken(); } //Concrete Product public class LinqtoSql : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:LinqtoSql"); } } //concrete product public class Subsonic : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:Subsonic"); } } //concrete product public class EntityFramework : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:EntityFramework"); } } //concrete product public class LightSpeed : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken :LightSpeed"); } } public class Creator { //Factory Method public IProduct ReturnORTool(ORMChoice choice) { switch (choice) { case ORMChoice.EFM:return new EntityFramework(); break; case ORMChoice.L2SQL:return new LinqtoSql(); break; case ORMChoice.LS:return new LightSpeed(); break; case ORMChoice.Sonic:return new Subsonic(); break; default: return null; } } } **Client** Button_Click() { Creator c = new Creator(); IProduct p = c.ReturnORTool(ORMChoice.L2SQL); p.ProductTaken(); } Is my understanding of Factory Method is correct?

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• Java method keyword "final" and its use

  - by Lukas Eder

  When I create complex type hierarchies (several levels, several types per level), I like to use the final keyword on methods implementing some interface declaration. An example: interface Garble { int zork(); } interface Gnarf extends Garble { /** * This is the same as calling {@link #zblah(0)} */ int zblah(); int zblah(int defaultZblah); } And then abstract class AbstractGarble implements Garble { @Override public final int zork() { ... } } abstract class AbstractGnarf extends AbstractGarble implements Gnarf { // Here I absolutely want to fix the default behaviour of zblah // No Gnarf shouldn't be allowed to set 1 as the default, for instance @Override public final int zblah() { return zblah(0); } // This method is not implemented here, but in a subclass @Override public abstract int zblah(int defaultZblah); } I do this for several reasons: It helps me develop the type hierarchy. When I add a class to the hierarchy, it is very clear, what methods I have to implement, and what methods I may not override (in case I forgot the details about the hierarchy) I think overriding concrete stuff is bad according to design principles and patterns, such as the template method pattern. I don't want other developers or my users do it. So the final keyword works perfectly for me. My question is: Why is it used so rarely in the wild? Can you show me some examples / reasons where final (in a similar case to mine) would be very bad?

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• Dealing with multiple generics in a method call

  - by thaBadDawg

  I've been dealing a lot lately with abstract classes that use generics. This is all good and fine because I get a lot of utility out of these classes but now it's making for some rather ugly code down the line. For example: abstract class ClassBase<T> { T Property { get; set; } } class MyClass : ClassBase<string> { OtherClass PropertyDetail { get; set; } } This implementation isn't all that crazy, except when I want to reference the abstract class from a helper class and then I have to make a list of generics just to make reference to the implemented class, like this below. class Helper { void HelpMe<C, T>(object Value) where C : ClassBase<T>, new() { DoWork(); } } This is just a tame example, because I have some method calls where the list of where clauses end up being 5 or 6 lines long to handle all of the generic data. What I'd really like to do is class Helper { void HelpMe<C>(object Value) where C : ClassBase, new() { DoWork(); } } but it obviously won't compile. I want to reference ClassBase without having to pass it a whole array of generic classes to get the function to work, but I don't want to reference the higher level classes because there are a dozen of those. Am I the victim of my own cleverness or is there an avenue that I haven't considered yet?

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• Can't get rails app to start on heroku

  - by jonnii

  I'm trying to deploy a rails app to heroku, but keep getting the following error. I'd have thought that managing the postgres gems would be something heroku would handle. I've tried everything I can think of short of installing postgres on my local machine, which I'd need to do if I wanted to install the postgres gem. There's also no gem called activerecord-postgresql-adapter... I'm guessing this is the standard adapter that comes with rails?? Any thoughts on how to fix this? App failed to start /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_specification.rb:76:in `establish_connection': Please install the postgresql adapter: `gem install activerecord-postgresql-adapter` (no such file to load -- pg) (RuntimeError) from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_specification.rb:60:in `establish_connection' from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_specification.rb:55:in `establish_connection' from /usr/local/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:438:in `initialize_database' from /usr/local/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:141:in `process' from /usr/local/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `send' from /usr/local/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `run' from /disk1/home/slugs/135415_c7f31f0_9f1f/mnt/config/environment.rb:9 from /usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' ... 14 levels... from /usr/local/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/builder.rb:29:in `instance_eval' from /usr/local/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/builder.rb:29:in `initialize' from /home/heroku_rack/heroku.ru:1:in `new' from /home/heroku_rack/heroku.ru:1

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• Retrieve values from multimdimensional array

  - by vincentlerry

  I have a great difficulty. I need to retrieve [title], [url] and [abstract] values ??from this multidimensional array. Also, I have to store those values in mysql database. thanks in advance!!! Array ( [bossresponse] = Array ( [responsecode] = 200 [limitedweb] = Array ( [start] = 0 [count] = 20 [totalresults] = 972000 [results] = Array ( [0] = Array ( [date] = [clickurl] = http://www.torchlake.com/ [url] = http://www.torchlake.com/ [dispurl] = www.torchlake.com [title] = Torch Lake, COLI Inc, Highspeed, Dial-up, Wireless ... [abstract] = Welcome to COLI Inc. Chain O' Lake Internet. Local Northern Michigan ISP, offering Dialup Internet access, Wireless access, Web design, and T1 services in Northern ... ) [1] = Array ( [date] = [clickurl] = http://en.wikipedia.org/wiki/Torch_Lake_(Antrim_County,_Michigan) [url] = http://en.wikipedia.org/wiki/Torch_Lake_(Antrim_County,_Michigan) [dispurl] = en.wikipedia.org/wiki/Torch_Lake_(Antrim_County,_Michigan) [title] = Torch Lake (Antrim County, Michigan) - Wikipedia, the free ... [abstract] = Torch Lake at 19 miles (31 km) long is Michigan's longest lake and at approximately 18,770 acres (76 km²) is Michigan's second largest lake. Within it are several ... ) this is the entire code that generates this array: require("OAuth.php"); $cc_key = ""; $cc_secret = ""; $url = "http://yboss.yahooapis.com/ysearch/limitedweb"; $args = array(); $args["q"] = "car"; $args["format"] = "json"; $args["count"] = 20; $consumer = new OAuthConsumer($cc_key, $cc_secret); $request = OAuthRequest::from_consumer_and_token($consumer, NULL,"GET", $url, $args); $request-sign_request(new OAuthSignatureMethod_HMAC_SHA1(), $consumer, NULL); $url = sprintf("%s?%s", $url, OAuthUtil::build_http_query($args)); $ch = curl_init(); $headers = array($request-to_header()); curl_setopt($ch, CURLOPT_HTTPHEADER, $headers); curl_setopt($ch, CURLOPT_URL, $url); curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE); $rsp = curl_exec($ch); $results = json_decode($rsp, true);

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• Why am I getting this error when overriding an inherited method?

  - by Sergio Tapia

  Here's my parent class: public abstract class BaseFile { public string Name { get; set; } public string FileType { get; set; } public long Size { get; set; } public DateTime CreationDate { get; set; } public DateTime ModificationDate { get; set; } public abstract void GetFileInformation(); public abstract void GetThumbnail(); } And here's the class that's inheriting it: public class Picture:BaseFile { public override void GetFileInformation(string filePath) { FileInfo fileInformation = new FileInfo(filePath); if (fileInformation.Exists) { Name = fileInformation.Name; FileType = fileInformation.Extension; Size = fileInformation.Length; CreationDate = fileInformation.CreationTime; ModificationDate = fileInformation.LastWriteTime; } } public override void GetThumbnail() { } } I thought when a method was overridden, I could do what I wanted with it. Any help please? :)

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• Problem with 2 levels of inheritance in hibernate mapping

  - by Seth

  Here's my class structure: class A class B extends A class C extends A class D extends C class E extends C And here are my mappings (class bodies omitted for brevity): Class A: @Entity @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @MappedSuperclass @DiscriminatorColumn( name="className", discriminatorType=DiscriminatorType.STRING ) @ForceDiscriminator public abstract class A Class B: @Entity @DiscriminatorValue("B") public class B extends A Class C: @Entity @DiscriminatorValue("C") @MappedSuperclass @DiscriminatorColumn( name="cType", discriminatorType=DiscriminatorType.STRING ) @ForceDiscriminator public abstract class C extends A Class D: @Entity @DiscriminatorValue("D") public class D extends C Class E: @Entity @DiscriminatorValue("E") public class E extends C I've got a class F that contains a set of A: @Entity public class F { ... @OneToMany(fetch=FetchType.LAZY, cascade=CascadeType.ALL) @JoinTable( name="F_A", joinColumns = @JoinColumn(name="A_ID"), inverseJoinColumns = @JoinColumn(name="F_ID") ) private Set<A> aSet = new HashSet<A>(); ... The problem is that whenever I add a new E instance to aSet and then call session.saveOrUpdate(fInstance), hibernate saves with "A" as the discrimiator string. When I try to access the aSet in the F instance, I get the following exception (full stacktrace ommitted for brevity): org.hibernate.InstantiationException: Cannot instantiate abstract class or interface: path.to.class.A Am I mapping the classes incorrectly? How am I supposed to map multiple levels of inheritance? Thanks for the help!

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• Why doesn't the spring @Autowire work with java generics

  - by testing123

  Inspired by spring data awesomeness I wanted to create a abstract RESTController that I could extend for a lot of my controllers. I created the following class: @Controller public abstract class RESTController<E, PK extends Serializable, R extends PagingAndSortingRepository<E, PK>> { @Autowired private R repository; @RequestMapping(method=RequestMethod.GET, params={"id"}) @ResponseBody public E getEntity(@RequestParam PK id) { return repository.findOne(id); } ... } I was hoping that the generics would allow me to @Autowire in the repository but I get the following error: SEVERE: Allocate exception for servlet appServlet org.springframework.beans.factory.NoSuchBeanDefinitionException: No unique bean of type [org.springframework.data.repository.PagingAndSortingRepository] is defined: expected single matching bean but found 3: [groupRepository, externalCourseRepository, managedCourseRepository] at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:800) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:707) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:478) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:284) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294) I understand what the error is telling me, there is more than one match for the @Autowire. I am confused because I thought by creating the following controller it would work: @Controller @RequestMapping(value="/managedCourse") public class ManagedCourseController extends RESTController<ManagedCourse, Long, ManagedCourseRepository> { ... } This is easy enough to work around by doing having a method like this in the RESTController: protected abstract R getRepository(); and then doing this in your implementing class: @Autowired private ManagedCourseRepository repository; @Override protected ManagedCourseRepository getRepository() { return repository; } I was just wondering if someone had any thoughts of how I could get this to work.

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• Reordering fields in Django model

  - by Alex Lebedev

  I want to add few fields to every model in my django application. This time it's created_at, updated_at and notes. Duplicating code for every of 20+ models seems dumb. So, I decided to use abstract base class which would add these fields. The problem is that fields inherited from abstract base class come first in the field list in admin. Declaring field order for every ModelAdmin class is not an option, it's even more duplicate code than with manual field declaration. In my final solution, I modified model constructor to reorder fields in _meta before creating new instance: class MyModel(models.Model): # Service fields notes = my_fields.NotesField() created_at = models.DateTimeField(auto_now_add=True) updated_at = models.DateTimeField(auto_now=True) class Meta: abstract = True last_fields = ("notes", "created_at", "updated_at") def __init__(self, *args, **kwargs): new_order = [f.name for f in self._meta.fields] for field in self.last_fields: new_order.remove(field) new_order.append(field) self._meta._field_name_cache.sort(key=lambda x: new_order.index(x.name)) super(TwangooModel, self).__init__(*args, **kwargs) class ModelA(MyModel): field1 = models.CharField() field2 = models.CharField() #etc ... It works as intended, but I'm wondering, is there a better way to acheive my goal?

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• Where should I put validation code?

  - by D Lawson

  I'm creating interfaces and abstract classes that represent a messaging framework for short text-based messages like SMS, email, twitter, xml, etc.. and I was wondering where I should put the message validation code. The thing is that I am only writing the superclasses and interfaces, so I'm not putting the actual implementation in, I'll just put the hooks in that allow others to validate the content of the messages. The way I see it, I could do it several ways: in the abstract superclass "Message", have an abstract method 'isValid'. A variation on this would be to have isValid be called when the Message constructor is called, throwing a MalformedMessageException if the message is formatted incorrectly. in the transport layer, immediately before sending, validate the message. I would have a send(Message) method that calls an isValid(Message) method immediately before it sends. have a singleton message validator with a static method isValid(Message) that is called at some point. I'm sure there are other options that I'm missing. Currently, I'm leaning towards the first one, but it doesn't feel right to me to have validation code in what should be a domain object.

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• Java - How to pass a Generic parameter as Class<T> to a constructor

  - by Joe Almore

  I have a problem here that still cannot solve, the thing is I have this abstract class: public abstract class AbstractBean<T> { private Class<T> entityClass; public AbstractBean(Class<T> entityClass) { this.entityClass = entityClass; }... Now I have another class that inherits this abstract: @Stateless @LocalBean public class BasicUserBean<T extends BasicUser> extends AbstractBean<T> { private Class<T> user; public BasicUserBean() { super(user); // Error: cannot reference user before supertype contructor has been called. } My question is how can I make this to work?, I am trying to make the class BasicUserBean inheritable, so if I have class PersonBean which inherits BasicUserBean then I could set in the Generic the entity Person which also inherits the entity BasicUser. And it will end up being: @Stateless @LocalBean public class PersonBean extends BasicUserBean<Person> { public PersonBean() { super(Person.class); } ... I just want to inherit the basic functionality from BasicUserBean to all descendants, so I do not have to repeat the same code among all descendants. Thanks!.

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• Generic factory of generic containers

  - by Feuermurmel

  I have a generic abstract class Factory<T> with a method createBoxedInstance() which returns instances of T created by implementations of createInstance() wrapped in the generic container Box<T>. abstract class Factory<T> { abstract T createInstance(); public final Box<T> createBoxedInstance() { return new Box<T>(createInstance()); } public final class Box<T> { public final T content; public Box(T content) { this.content = content; } } } At some points I need a container of type Box<S> where S is an ancestor of T. Is it possible to make createBoxedInstance() itself generic so that it will return instances of Box<S> where S is chosen by the caller? Sadly, defining the function as follows does not work as a type parameter cannot be declared using the super keyword, only used. public final <S super T> Box<S> createBoxedInstance() { return new Box<S>(createInstance()); } The only alternative I see, is to make all places that need an instance of Box<S> accept Box<? extends S> which makes the container's content member assignable to S. Is there some way around this without re-boxing the instances of T into containers of type Box<S>? (I know I could just cast the Box<T> to a Box<S> but I would feel very, very guilty.)

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• Enums and inheritance

  - by devoured elysium

  I will use (again) the following class hierarchy: Event and all the following classes inherit from Event: SportEventType1 SportEventType2 SportEventType3 SportEventType4 I have originally designed the Event class like this: public abstract class Event { public abstract EventType EventType { get; } public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } with EventType being defined as: public enum EventType { Sport1, Sport2, Sport3, Sport4 } The original idea would be that each SportEventTypeX class would set its correct EventType. Now that I think of it, I think this approach is totally incorrect for two reasons: If I want to later add a new SportEventType class I will have to modify the enum If I later decide to remove one SportEventType that I feel I won't use I'm also in big trouble with the enum. I have a class variable in the Event class that makes, afterall, assumptions about the kind of classes that will inherit from it, which kinda defeats the purpose of inheritance. How would you solve this kind of situation? Define in the Event class an abstract "Description" property, having each child class implement it? Having an Attribute(Annotation in Java!) set its Description variable instead? What would be the pros/cons of having a class variable instead of attribute/annotation in this case? Is there any other more elegant solution out there? Thanks

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• Setting up Rails to work with sqlserver

  - by FortunateDuke

  Ok I followed the steps for setting up ruby and rails on my Vista machine and I am having a problem connecting to the database. Contents of database.yml development: adapter: sqlserver database: APPS_SETUP Host: WindowsVT06\SQLEXPRESS Username: se Password: paswd Run rake db:migrate from myapp directory ---------- rake aborted! no such file to load -- deprecated ADO I have dbi 0.4.0 installed and have created the ADO folder in C:\Ruby\lib\ruby\site_ruby\1.8\DBD\ADO I got the ado.rb from the dbi 0.2.2 What else should I be looking at to fix the issue connecting to the database? Please don't tell me to use MySql or Sqlite or Postgres. *UPDATE* I have installed the activerecord-sqlserver-adapter gem from --source=http://gems.rubyonrails.org Still not working. I have verified that I can connect to the database by logging into SQL Management Studio with the credentials. rake db:migrate --trace PS C:\Inetpub\wwwroot\myapp> rake db:migrate --trace (in C:/Inetpub/wwwroot/myapp) ** Invoke db:migrate (first_time) ** Invoke environment (first_time) ** Execute environment ** Execute db:migrate rake aborted! no such file to load -- deprecated C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require' C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:510:in `require' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:355:in `new_constants_in' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:510:in `require' C:/Ruby/lib/ruby/site_ruby/1.8/dbi.rb:48 C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require' C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:510:in `require' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:355:in `new_constants_in' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:510:in `require' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/core_ext/kernel/requires.rb:7:in `require_library_ or_gem' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/core_ext/kernel/reporting.rb:11:in `silence_warnin gs' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/core_ext/kernel/requires.rb:5:in `require_library_ or_gem' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-sqlserver-adapter-1.0.0.9250/lib/active_record/connection_adapters/sqlserver _adapter.rb:29:in `sqlserver_connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/connection_adapters/abstract/connection_specificatio n.rb:292:in `send' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/connection_adapters/abstract/connection_specificatio n.rb:292:in `connection=' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/connection_adapters/abstract/connection_specificatio n.rb:260:in `retrieve_connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/connection_adapters/abstract/connection_specificatio n.rb:78:in `connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/migration.rb:408:in `initialize' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/migration.rb:373:in `new' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/migration.rb:373:in `up' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/migration.rb:356:in `migrate' C:/Ruby/lib/ruby/gems/1.8/gems/rails-2.1.1/lib/tasks/databases.rake:99 C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:621:in `call' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:621:in `execute' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:616:in `each' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:616:in `execute' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:582:in `invoke_with_call_chain' C:/Ruby/lib/ruby/1.8/monitor.rb:242:in `synchronize' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:575:in `invoke_with_call_chain' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:568:in `invoke' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2031:in `invoke_task' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2009:in `top_level' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2009:in `each' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2009:in `top_level' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2048:in `standard_exception_handling' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2003:in `top_level' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:1982:in `run' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2048:in `standard_exception_handling' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:1979:in `run' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/bin/rake:31 C:/Ruby/bin/rake:19:in `load' C:/Ruby/bin/rake:19 PS C:\Inetpub\wwwroot\myapp>

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• On REST: WADL or not IDL, is the following approach right ?

  - by redben

  This question is a bit long, please bear with me. In REST, i think we should not need WADL or any IDL. But rather something that would implicitly cover its concept. The way I think about it is when we (humans) surf the Web, when we go to a web site for the first time, we don't know what services it provides. You discover those on the html home page (or a sitemap page in a help section) or maybe just the main menu on the home page. If you make an analogy, the homepage or site map to us humans is what WSDL is to WS-* or what WADL could be to a REST service. Only that its just like any other html content. I think that in REST the following is a good way to do things, respecting the HATEOS paradigm. Have a top level (or default) resource that lists links to your other resources. For a library example, say RestLibrary.com/ it could be something like: <root xmlns:lib="http://librarystandards.com/libraryml"> <resource class="lib:book"> <link type="application/vnd.libraryml+xml" template="mylib.com/book/{isbn}" /> <link type="application/vnd.libraryml+xml" rel="add" href="mylib.com/book" method="POST" /> <link type="application/vnd.libraryml+xml" rel="update" template="mylib.com/book/{isbn}" method="PUT" /> </resource> <resource class="lib:bookList"> <link template="mylib.com/book?keywords={keywords}" type="application/vnd.openlibrary+xml" rel="search" /> </resource> </root> Note that it is assumed that the media type "application/vnd.libraryml+xml" is a defined standard or (may be just proprietary vocabulary) named libraryml. Also, the client should be able to understand this "homepage" resource (elements root, resource and link). This is the part that could be used instead of WADL : an Abstract vocabulary that should be understandable by any client. You could use an existing standard like Atom for example. But the main idea is to have an abstract vocabulary understandable by any client. Why not WADL then ? well wadl is only for service discovery. The idea here is to have an light abstract vocabulary that would serve as a base for hypermedia. A "root" vocabulary. Like in owl we have owl:thing...etc Now if the client knows the "libraryml" standard it can follow the links to the things it understands (after parsing the media type properties and xmlns). If not, it just won't. When i can't understand how to deal with something in REST architecture i tend to see how we Humans do it in the Web. In the Web, we have the Generic language that is HTML that enables site builders to deliver any specific content, regardless of its meaning to the client (the user), Browsers understand HTML but not the "meaning" of its content. It is the user that understands the (domain specific) content. If i go to say QuantumPhysics.org, my browser can render the home page (it is just html after all) and i can read the home page. If i understand quantum then fine i can continue browsing. If i don't i just get out (unless i want to learn the hardway :) ) In the RetsLibrary.com example the client app is just like me+my browser on QuantumPhysics.org. the media type "application/vnd.libraryml+xml" is quantum physics (knowledge). http is http in both examples. Now HTML of QuantumPhysics.org is in RestLibrary.com is XML + that tiny little abstract vocabulary (root resource and link, that you could replace with something like Atom). So does this approach have any value ? don't we need a root tiny hyper-vocabulary so we can succeed with hypermedia and the "initial URI" concept ? edit Yeah why not RDF as the root vocabulary !

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• Crypted_password is null when using Authlogic to save a user

  - by kareem

  i'm getting a strange error on my production install when i try and create a new user using AL: ActiveRecord::StatementInvalid: Mysql::Error: Column 'crypted_password' cannot be null: INSERT INTO users especially strange b/c it works as expected on my local box. RUnning Rails 2.3.2 and ruby 1.8.7 on both boxes. user.rb: class User < ActiveRecord::Base before_create :set_username acts_as_authentic do |c| c.require_password_confirmation = false c.login_field = "email" c.validates_length_of_password_field_options = {:minimum => 4} c.validate_login_field = false #don't validate email field with additional validations end end Here's output from my production console: >> u = User.new => #<User id: nil, username: nil, email: nil, crypted_password: nil, password_salt: nil, persistence_token: nil, single_access_token: nil, perishable_token: nil, login_count: 0, failed_login_count: 0, last_request_at: nil, current_login_at: nil, last_login_at: nil, current_login_ip: nil, last_login_ip: nil, created_at: nil, updated_at: nil, is_admin: 0, first_name: nil, last_name: nil> >> u.full_name = 'john smith' => "john smith" >> u.password = 'test' => "test" >> u.email = '[email protected]' => "[email protected]" >> u.valid? => true >> u.save ActiveRecord::StatementInvalid: Mysql::Error: Column 'crypted_password' cannot be null: INSERT INTO `users` (`single_access_token`, `last_request_at`, `created_at`, `crypted_password`, `perishable_token`, `updated_at`, `username`, `failed_login_count`, `current_login_ip`, `password_salt`, `current_login_at`, `is_admin`, `persistence_token`, `login_count`, `last_name`, `last_login_ip`, `last_login_at`, `email`, `first_name`) VALUES('B-XSXwhO7hkbtISIOyEq', NULL, '2009-07-31 01:10:44', NULL, 'FK3mYS2Tp5Tzeq5IXE1z', '2009-07-31 01:10:44', 'john', 0, NULL, NULL, NULL, 0, '2c76b645f761eb3509353290e93874cecdb68a63caa165812ab1b126d63660757090ecf69995caef9e78f93d070b524e2542b3fec4ee050726088c2a9fdb0c9f', 0, 'smith', NULL, NULL, '[email protected]', 'john') from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/abstract_adapter.rb:212:in `log' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/mysql_adapter.rb:320:in `execute' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/abstract/database_statements.rb: 259:in `insert_sql' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/mysql_adapter.rb:330:in `insert_sql' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/abstract/database_statements.rb: 44:in `insert_without_query_dirty' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/abstract/query_cache.rb:18:in `insert' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/base.rb:2902:in `create_without_timestamps' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/timestamp.rb:29:in `create_without_callbacks' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/callbacks.rb:266:in `create' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/base.rb:2868:in `create_or_update_without_callbacks' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/callbacks.rb:250:in `create_or_update' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/base.rb:2539:in `save_without_validation' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/validations.rb:1009:in `save_without_dirty' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/dirty.rb:79:in `save_without_transactions' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:229:in `send' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:229:in `with_transaction_returning_status' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/abstract/database_statements.rb: 136:in `transaction' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:182:in `transaction' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:228:in `with_transaction_returning_status' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:196:in `save' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:208:in `rollback_active_record_state!' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:196:in `save' No idea why this is happening, and especially why this saves a new user on dev but not on production. Any help is much appreciated, thanks! edit: using Apache & Passenger 2.2.4

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• Servlet response wrapper has encoding problem

  - by John O

  A servlet response wrapper is being used in a Servlet Filter. The idea is that the response is manipulated, with a 'nonce' value being injected into forms, as part of defence against CSRF attacks. The web app is using UTF-8 everywhere. When the Servlet Filter is absent, no problems. When the filter is added, encoding issues occur. (It seems as if the response is reverting to 8859-1.) The guts of the code : final class CsrfResponseWrapper extends AbstractResponseWrapper { ... byte[] modifyResponse(byte[] aInputResponse){ ... String originalInput = new String(aInputResponse, encoding); String modifiedResult = addHiddenParamToPostedForms(originalInput); result = modifiedResult.getBytes(encoding); ... } ... } As I understand it, the transition between byte-land and String-land should specify an encoding. That is done here, as you can see, in two places. The value of the 'encoding' variable is 'UTF-8'; the alteration of the String itself is standard string manipulation (with a regex), and never specifies an encoding (addHiddenParamToPostedForms). Where am I in error about the encoding? EDIT: Here is the base class (sorry it's rather long): package hirondelle.web4j.security; import javax.servlet.ServletOutputStream; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpServletResponseWrapper; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.PrintWriter; /** Abstract Base Class for altering response content. (May be useful in future contexts as well. For now, keep package-private.) */ abstract class AbstractResponseWrapper extends HttpServletResponseWrapper { AbstractResponseWrapper(ServletResponse aServletResponse) throws IOException { super((HttpServletResponse)aServletResponse); fOutputStream = new ModifiedOutputStream(aServletResponse.getOutputStream()); fWriter = new PrintWriter(fOutputStream); } /** Return the modified response. */ abstract byte[] modifyResponse(byte[] aInputResponse); /** Standard servlet method. */ public final ServletOutputStream getOutputStream() { //fLogger.fine("Modified Response : Getting output stream."); if ( fWriterReturned ) { throw new IllegalStateException(); } fOutputStreamReturned = true; return fOutputStream; } /** Standard servlet method. */ public final PrintWriter getWriter() { //fLogger.fine("Modified Response : Getting writer."); if ( fOutputStreamReturned ) { throw new IllegalStateException(); } fWriterReturned = true; return fWriter; } // PRIVATE /* Well-behaved servlets return either an OutputStream or a PrintWriter, but not both. */ private PrintWriter fWriter; private ModifiedOutputStream fOutputStream; /* These items are used to implement conformance to the javadoc for ServletResponse, regarding exceptions being thrown. */ private boolean fWriterReturned; private boolean fOutputStreamReturned; /** Modified low level output stream. */ private class ModifiedOutputStream extends ServletOutputStream { public ModifiedOutputStream(ServletOutputStream aOutputStream) { fServletOutputStream = aOutputStream; fBuffer = new ByteArrayOutputStream(); } /** Must be implemented to make this class concrete. */ public void write(int aByte) { fBuffer.write(aByte); } public void close() throws IOException { if ( !fIsClosed ){ processStream(); fServletOutputStream.close(); fIsClosed = true; } } public void flush() throws IOException { if ( fBuffer.size() != 0 ){ if ( !fIsClosed ) { processStream(); fBuffer = new ByteArrayOutputStream(); } } } /** Perform the core processing, by calling the abstract method. */ public void processStream() throws IOException { fServletOutputStream.write(modifyResponse(fBuffer.toByteArray())); fServletOutputStream.flush(); } // PRIVATE // private ServletOutputStream fServletOutputStream; private ByteArrayOutputStream fBuffer; /** Tracks if this stream has been closed. */ private boolean fIsClosed = false; } }

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• Attend my Fusion sessions

  - by Daniel Moth

  The inaugural Fusion conference was 1 year ago in June 2011 and I was there doing a demo in the keynote, and also presenting a breakout session. If you look at the abstract and title for that session you won't see the term "C++ AMP" in there because the technology wasn't announced and we didn't want to spill the beans ahead of the keynote, where the technology was announced. It was only an announcement, we did not give any bits out, and in fact the first bits came three months later in September 2011 with the Beta following in February 2012. So it really feels great 1 year later, to be back at Fusion presenting two sessions on C++ AMP, demonstrating our progress from that announcement, to the Visual Studio 2012 Release Candidate that came out last week. If you are attending Fusion (in person or virtually later), be sure to watch my two-part session. Part 1 is PT-3601 on Tuesday 4pm and part 2 is PT-3602 on Wednesday 4pm. Here is the shared abstract for both parts: Harnessing GPU Compute with C++ AMP C++ AMP is an open specification for taking advantage of accelerators like the GPU. In this session we will explore the C++ AMP implementation in Microsoft Visual Studio 2012. After a quick overview of the technology understanding its goals and its differentiation compared with other approaches, we will dive into the programming model and its modern C++ API. This is a code heavy, interactive, two-part session, where every part of the library will be explained. Demos will include showing off the richest parallel and GPU debugging story on the market, in the upcoming Visual Studio release. See you there! Comments about this post by Daniel Moth welcome at the original blog.

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• BizTalk 2009 - Naming Guidelines

  - by StuartBrierley

  The following is effectively a repost of the BizTalk 2004 naming guidlines that I have previously detailed.  I have posted these again for completeness under BizTalk 2009 and to allow an element of separation in case I find some reason to amend these for BizTalk 2009. These guidlines should be universal across any version of BizTalk you may wish to apply them to. General Rules All names should be named with a Pascal convention. Project Namespaces For message schemas: [CompanyName].XML.Schemas.[FunctionalName]* Examples:  ABC.XML.Schemas.Underwriting DEF.XML.Schemas.MarshmellowTradingExchange * Donates potential for multiple levels of functional name, such as Underwriting.Dictionary.Valuation For web services: [CompanyName].Web.Services.[FunctionalName] Examples: ABC.Web.Services.OrderJellyBeans For the main BizTalk Projects: [CompanyName].BizTalk.[AssemblyType].[FunctionalName]* Examples: ABC.BizTalk.Mappings.Underwriting ABC.BizTalk.Orchestrations.Underwriting * Donates potential for multiple levels of functional name, such as Mappings.Underwriting.Valuations Assemblies BizTalk Assembly names should match the associated Project Namespace, such as ABC.BizTalk.Mappings.Underwriting. This pertains to the formal assembly name and the DLL name. The Solution name should take the name of the main project within the solution, and also therefore the namespace for that project. Although long names such as this can be unwieldy to work with, the benefits of having the full scope available when the assemblies are installed on the target server are generally judged to outweigh this inconvenience. Messaging Artifacts Artifact Standard Notes Example Schema <DescriptiveName>.xsd   .NET Type name should match, without file extension.    .NET Namespace will likely match assembly name. PurchaseOrderAcknowledge_FF.xsd  or FNMA100330_FF.xsd Property Schema <DescriptiveName>.xsd Should be named to reflect possible common usage across multiple schemas  IspecMessagePropertySchema.xsd UnderwritingOrchestrationKeys.xsd Map <SourceSchema>2<DestinationSchema>.btm Exceptions to this may be made where the source and destination schemas share the majority of the name, such as in mainframe web service maps InstructionResponse2CustomEmailRequest.btm (exception example) AccountCustomerAddressSummaryRequest2MainframeRequest.btm Orchestration <DescriptiveName>.odx   GetValuationReports.odx SendMTEDecisionResponse.odx Send/Receive Pipeline <DescriptiveName>.btp   ValidatingXMLReceivePipeline.btp FlatFileAssembler.btp Receive Port A plainly worded phrase that will clearly explain the function.    FraudPreventionServices LetterProcessing   Receive Location A plainly worded phrase that will clearly explain the function.  ? Do we want to include the transport type here ? Arrears Web Service Send Port Group A plainly worded phrase that will clearly explain the function.   Customer Updates Send Port A plainly worded phrase that will clearly explain the function.    ABCProductUpdater LogLendingPolicyOutput Parties A meaningful name for a Trading Partner. If dealing with multiple entities within a Trading Partner organization, the Organization name could be used as a prefix.   Roles A meaningful name for the role that a Trading Partner plays.     Orchestration Workflow Shapes Shape Standard Notes Example Scopes <DescriptionOfContainedWork> or <DescOfcontainedWork><TxType>   Including info about transaction type may be appropriate in some situations where it adds significant documentation value to the diagram. HandleReportResponse         Receive Receive<MessageName> Typically, MessageName will be the same as the name of the message variable that is being received “into”. ReceiveReportResponse Send Send<MessageName> Typically, MessageName will be the same as the name of the message variable that is being sent. SendValuationDetailsRequest Expression <DescriptionOfEffect> Expression shapes should be named to describe the net effect of the expression, similar to naming a method.  The exception to this is the case where the expression is interacting with an external .NET component to perform a function that overlaps with existing BizTalk functionality – use closest BizTalk shape for this case. CreatePrintXML Decide <DescriptionOfDecision> A description of what will be decided in the “if” branch Report Type? Perform MF Save? If-Branch <DescriptionOfDecision> A (potentially abbreviated) description of what is being decided Mortgage Valuation Yes Else-Branch Else Else-branch shapes should always be named “Else” Else Construct Message (Assign) Create<Message> (for Construct)     <ExpressionDescription> (for expression) If a Construct shape contains a message assignment, it should be prefixed with “Create” followed by an abbreviated name of the message being assigned.    The actual message assignment shape contained should be named to describe the expression that is contained. CreateReportDataMV   which contains expression: ExtractReportData Construct Message (Transform) Create<Message> (for Construct)   <SourceSchema>2<DestSchema> (for transform) If a Construct shape contains a message transform, it should be prefixed with “Create” followed by an abbreviated name of the message being assigned.   The actual message transform shape contained should generally be named the same as the called map.  CreateReportDataMV   which contains transform: ReportDataMV2ReportDataMV                 Construct Message (containing multiple shapes)   If a Construct Message shape uses multiple assignments or transforms, the overall shape should be named to communicate the net effect, using no prefix.     Call/Start Orchestration Call<OrchestrationName>   Start<OrchestrationName>     Throw Throw<ExceptionType> The corresponding variable name for the exception type should (often) be the same name as the exception type, only camel-cased. ThrowRuleException, which references the “ruleException” variable.     Parallel <DescriptionOfParallelWork> Parallel shapes should be named by a description of what work will be done in parallel   Delay <DescriptionOfWhatWaitingFor> Delay shapes should be named by a description of what is being waited for.  POAcknowledgeTimeout Listen <DescriptionOfOutcomes> Listen shapes should be named by a description that captures (to the degree possible) all the branches of the Listen shape POAckOrTimeout FirstShippingBid Loop <DescriptionOfLoop> A (potentially abbreviated) description of what the loop is. ForEachValuationReport WhileErrorFlagTrue Role Link   See “Roles” in messaging naming conventions above.   Suspend <ReasonDescription> Describe what action an administrator must take to resume the orchestration.  More detail can be passed to error property – and should include what should be done by the administrator before resuming the orchestration. ReEstablishCreditLink Terminate <ReasonDescription> Describe why the orchestration terminated.  More detail can be passed to error property. TimeoutsExpired Call Rules Call<PolicyName> The policy name may need to be abbreviated. CallLendingPolicy Compensate Compensate or Compensate<TxName> If the shape compensates nested transactions, names should be suffixed with the name of the nested transaction – otherwise it should simple be Compensate. CompensateTransferFunds Orchestration Types Type Standard Notes Example Multi-Part Message Types <LogicalDocumentType>   Multi-part types encapsulate multiple parts.  The WSDL spec indicates “parts are a flexible mechanism for describing the logical abstract content of a message.”  The name of the multi-part type should correspond to the “logical” document type, i.e. what the sum of the parts describes. InvoiceReceipt   (which might encapsulate an invoice acknowledgement and a payment voucher.) Multi-Part Messsage Part <SchemaNameOfPart> Should be named (most often) simply for the schema (or simple type) associated with the part. InvoiceHeader Messages <SchemaName> or <MuliPartMessageTypeName> Should be named based on the corresponding schema type or multi-part message type.  If there is more than one variable of a type, name for its use within the orchestration. ReportDataMV UpdatedReportDataMV Variables <DescriptiveName>   TargetFilePath StringProcessor Port Types <FunctionDescription>PortType Should be named to suggest the nature of an endpoint, with pascal casing and suffixed with “PortType”.   If there will be more than one Port for a Port Type, the Port Type should be named according to the abstract service supplied.   The WSDL spec indicates port types are “a named set of abstract operations and the abstract messages involved” that also encapsulates the message pattern (i.e. one-way, request-response, solicit-response) that all operations on the port type adhere to. ReceiveReportResponsePortType  or CallEAEPortType (This is a two way port, so Receove or Send alone would not be appropriate.  Could have been ProcessEAERequestPortType etc....) Ports <FunctionDescription>Port Should be named to suggest a grouping of functionality, with pascal casing and suffixed with “Port.”  ReceiveReportResponsePort CallEAEPort Correlation types <DescriptiveName> Should be named based on the logical name of what is being used to correlate.  PurchaseOrderNumber Correlation sets <DescriptiveName> Should be named based on the corresponding correlation type.  If there is more than one, it should be named to reflect its specific purpose within the orchestration.   PurchaseOrderNumber Orchestration parameters <DescriptiveName> Should be named to match the caller’s names for the corresponding variables where appropriate.

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• Teaching myself, as a physicist, to become a better programmer

  - by user787267

  I've always liked physics, and I've always liked coding, so when I got the offer for a PhD position doing numerical physics (details are not relevant, it's mostly parallel programming for a cluster) at a university, it was a no-brainer for me. However, as most physicists, I'm self taught. I don't have broad background knowledge about how to code in an object oriented way, or the name of that specific algorithm that optimizes the search in some kD tree. Since all my work so far has been more concerned about the physics and the scientific results, I undoubtedly have some bad habits - more so because my coding is my own, and not really teamwork. I have mostly used C since it is very straightforward and "what you write is what you get" - no need for fancy abstractions. However, I have recently switched to C++ since I'd like to learn more about the power that comes with abstraction, and it's pretty C-like (syntax-wise at least). How do I teach myself to code in a good, abstract way like a graduate in computer science? I know my code is efficient, but I want it to be elegant as well, and readable. Keep in mind that I don't have time to read several 1000-page tomes about abstract programming. I need to spend time on actual, physics related research (my supervisor would laugh at me if he knew I spent time thinking about how to program elegantly). How do I assess if my work is also good from a programmer's perspective?

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• Correct level of abstraction for a 3d rendering component?

  - by JohnB

  I've seen lots of questions around this area but not this exact question so apologies if this is a duplicate. I'm making a small 3d game. Well to be honest, it's just a little hobby project and likely won't turn out to be an actual game, I'll be happy to make a nice graphics demo and learn about 3d rendering and c++ design. My intent is to use direct3d9 for rendering as I have some little experience of it, and it seems to meet my requirements. However if I've learned one thing as a programmer it's to ask "is there any conceivable reason that this component might be replaced by a different implmentation" and if the answer is yes then I need to design a proper abstraction and interface to that component. So even though I intend to implment d3d9 I need to design a 3d interface that could be implemented for d3d11, opengl... My question then is what level is it best to do this at? I'm thinking that an interface capable of creating and later drawing Vertex buffers and index buffers Textures Vertex and Pixel "shaders" Some representation of drawing state (blending modes etc...) In other words a fairly low level interface where my code to draw for example an animated model would use the interface to obtain abstract vertex buffers etc. I worry though that it's too low level to abstract out all the functionallity I need efficiently. The alternative is to do this at a higher level where the interface can draw objects, animations, landscapes etc, and implement them for each system. This seems like more work, but it more flexible I guess. So that's my question really, when abstracting out the drawing system, what level of interface works best?

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• Is this kind of Design by Contract useless?

  - by Charlie Pigarelli

  I've just started informatics university and I'm attending a programming course about C(++). The programming professor prefers to teach very few things (in 3 month we have just reached the functions topic) and connect every topic with a type of programming design that somehow is similar to the Design by Contract design. Basically what he ask us to do is to write every exercise with comments Pre-conditions, Post-conditions and Invariants that should prove the correctness of each program we write. But this doesn't make any sense to me. I mean, ok: maybe writing down your thoughts prevent you from doing some mistakes, but if this is all an abstract thing, then if your program intuition is wrong you'll write your program wrong and then you'll also write pre and post conditions wrong probably auto convincing your self about its correctness. Most of the time, both me and other students have written programs that seemed ok and that had correct pre and post condition too. But at the moment of testing it was just completely wrong. I had some experience before this course of programming and I had written a lot of line of code before and I found myself comfortably with just writing a program and unit test it. It take less time to accomplish and is less "abstract" than just thinking about what every single piece of your program should do in every case (which is kinda like mentally testing it). Finally, all this pre and post conditions takes me like 80% of the total time of the exercise. It's harder to think about putting down this pre and post correct than to write the program itself. Since we are like the only course of the only university probably in the entire world that makes this things, could someone please tell me how should I manage this thing? Am I right thinking that this doesn't worth anything? Should I change university? (there are like double of the people attending that course and it seems that usually very few people passes the exam the first year). Should I convince myself it's method is right?

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• Speaking at SPTechCon Boston 2012

  - by Brian Jackett

  I will be speaking at SPTechCon Boston 2012.  This will be my 3rd time speaking at SPTechCon and 4th time attending.  The conference has steadily been growing over the past few years and is one of the biggest non-Microsoft run conferences for SharePoint in the US.  I’ll be presenting two topics which I have given before but this time around with some updated content.  Registration is currently open and you can save $200 (on top of the current early bird discount of $400) by using the code "JACKETT” during registration.  I highly recommend joining for valuable learning and networking.   Where: SPTechCon Boston 2012 Title: PowerShell for the SharePoint 2010 Developer Audience and Level: Developer, Intermediate Abstract: PowerShell is not just for SharePoint 2010 administrators. Developers also get access to a wide range of functionality with PowerShell. In this session we will dive into using PowerShell with the .Net framework, web services, and native SharePoint commandlets. We will also cover some of the more intermediate to advanced techniques available within PowerShell that will improve your work efficiency. Not only will you learn how to automate your work but also learn ways to prototype solutions faster. This session is targeted to developers and assumes a basic familiarity with PowerShell. Slides and Code download: coming soon   Title: Integrating Line-of-Business Applications with SharePoint 2010 Audience and Level: Developer, Intermediate Abstract: One of the biggest value-adding enhancements in SharePoint 2010 is the Business Connectivity Services (BCS). In this session, we will overview the BCS, demonstrate connecting line-of-business applications and external systems to SharePoint through external content types, and walk through surfacing that data with external lists. This session is targeted at developers. No prior experience with the BCS is required, but a basic understanding of SharePoint Designer 2010 and SharePoint solutions is suggested. Slides and Code download: coming soon         -Frog Out

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• Got a Great Solaris Story to Tell? Come to OpenWorld and Tell It

  - by Larry Wake

  I know there are a lot of Solaris veterans that still haven't experienced the enormousness that is Oracle OpenWorld. Simply put: if you have a chance to go, you should go. You'll learn a lot, and you'll be in one of the greatest cities in the world at the same time. Even better: if you've got something to share, we might be able to get you in for free. Yep, it's that time already: the Call for Papers for this year's OpenWorld (and JavaOne) is open.  But not for long -- you've only got until April 9th to submit your abstract. As a Solaris person, you'll probably be most interested in participating in one of two tracks: SERVER AND STORAGE SYSTEMS: Oracle Solaris ORACLE DEVELOP: Oracle Solaris and Oracle Linux Development All you need to give us right now is a title and an abstract. If your session is accepted, we'll let you know by early June, and you can start to plan to join us in San Francisco from September 30 to October 4. (If you're planning on attending in listen-only mode, be aware that the early registration price is available until March 30.) As is true every year, this is your opportunity to meet the leading Oracle hardware and software engineers, including lots of the Oracle Solaris team, and interact with your peers from all over the world. See you there!

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