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• Future Of F# At Jazoon 2011

  - by Alois Kraus

  I was at the Jazoon 2011 in Zurich (Switzerland). It was a really cool event and it had many top notch speaker not only from the Microsoft universe. One of the most interesting talks was from Don Syme with the title: F# Today/F# Tomorrow. He did show how to use F# scripting to browse through open databases/, OData Web Services, Sharepoint, …interactively. It looked really easy with the help of F# Type Providers which is the next big language feature in a future F# version. The object returned by a Type Provider is used to access the data like in usual strongly typed object model. No guessing how the property of an object is called. Intellisense will show it just as you expect. There exists a range of Type Providers for various data sources where the schema of the stored data can somehow be dynamically extracted. Lets use e.g. a free database it would be then let data = DbProvider(http://.....); data the object which contains all data from e.g. a chemical database. It has an elements collection which contains an element which has the properties: Name, AtomicMass, Picture, …. You can browse the object returned by the Type Provider with full Intellisense because the returned object is strongly typed which makes this happen. The same can be achieved of course with code generators that use an input the schema of the input data (OData Web Service, database, Sharepoint, JSON serialized data, …) and spit out the necessary strongly typed objects as an assembly. This does work but has the downside that if the schema of your data source is huge you will quickly run against a wall with traditional code generators since the generated “deserialization” assembly could easily become several hundred MB. *** The following part contains guessing how this exactly work by asking Don two questions **** Q: Can I use Type Providers within C#? D: No. Q: F# is after all a library. I can reference the F# assemblies and use the contained Type Providers? D: F# does annotate the generated types in a special way at runtime which is not a static type that C# could use. The F# type providers seem to use a hybrid approach. At compilation time the Type Provider is instantiated with the url of your input data. The obtained schema information is used by the compiler to generate static types as usual but only for a small subset (the top level classes up to certain nesting level would make sense to me). To make this work you need to access the actual data source at compile time which could be a problem if you want to keep the actual url in a config file. Ok so this explains why it does work at all. But in the demo we did see full intellisense support down to the deepest object level. It looks like if you navigate deeper into the object hierarchy the type provider is instantiated in the background and attach to a true static type the properties determined at run time while you were typing. So this type is not really static at all. It is static if you define as a static type that its properties shows up in intellisense. But since this type information is determined while you are typing and it is not used to generate a true static type and you cannot use these “intellistatic” types from C#. Nonetheless this is a very cool language feature. With the plotting libraries you can generate expressive charts from any datasource within seconds to get quickly an overview of any structured data storage. My favorite programming language C# will not get such features in the near future there is hope. If you restrict yourself to OData sources you can use LINQPad to query any OData enabled data source with LINQ with ease. There you can query Stackoverflow with The output is also nicely rendered which makes it a very good tool to explore OData sources today.

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• dynamic? I'll never use that ... or then again, maybe it could ...

  - by adweigert

  So, I don't know about you, but I was highly skeptical of the dynamic keywork when it was announced. I thought to myself, oh great, just another move towards VB compliance. Well after seeing it being used in things like DynamicXml (which I use for this example) I then was working with a MVC controller and wanted to move some things like operation timeout of an action to a configuration file. Thinking big picture, it'd be really nice to have configuration for all my controllers like that. Ugh, I don't want to have to create all those ConfigurationElement objects... So, I started thinking self, use what you know and do something cool ... Well after a bit of zoning out, self came up with use a dynamic object duh! I was thinking of a config like this ...<controllers> <add type="MyApp.Web.Areas.ComputerManagement.Controllers.MyController, MyApp.Web"> <detail timeout="00:00:30" /> </add> </controllers> So, I ended up with a couple configuration classes like this ...blic abstract class DynamicConfigurationElement : ConfigurationElement { protected DynamicConfigurationElement() { this.DynamicObject = new DynamicConfiguration(); } public DynamicConfiguration DynamicObject { get; private set; } protected override bool OnDeserializeUnrecognizedAttribute(string name, string value) { this.DynamicObject.Add(name, value); return true; } protected override bool OnDeserializeUnrecognizedElement(string elementName, XmlReader reader) { this.DynamicObject.Add(elementName, new DynamicXml((XElement)XElement.ReadFrom(reader))); return true; } } public class ControllerConfigurationElement : DynamicConfigurationElement { [ConfigurationProperty("type", Options = ConfigurationPropertyOptions.IsRequired | ConfigurationPropertyOptions.IsKey)] public string TypeName { get { return (string)this["type"]; } } public Type Type { get { return Type.GetType(this.TypeName, true); } } } public class ControllerConfigurationElementCollection : ConfigurationElementCollection { protected override ConfigurationElement CreateNewElement() { return new ControllerConfigurationElement(); } protected override object GetElementKey(ConfigurationElement element) { return ((ControllerConfigurationElement)element).Type; } } And then had to create the meat of the DynamicConfiguration class which looks like this ...public class DynamicConfiguration : DynamicObject { private Dictionary<string, object> properties = new Dictionary<string, object>(StringComparer.CurrentCultureIgnoreCase); internal void Add<T>(string name, T value) { this.properties.Add(name, value); } public override bool TryGetMember(GetMemberBinder binder, out object result) { var propertyName = binder.Name; result = null; if (this.properties.ContainsKey(propertyName)) { result = this.properties[propertyName]; } return true; } } So all being said, I made a base controller class like a good little MVC-itizen ...public abstract class BaseController : Controller { protected BaseController() : base() { var configuration = ManagementConfigurationSection.GetInstance(); var controllerConfiguration = configuration.Controllers.ForType(this.GetType()); if (controllerConfiguration != null) { this.Configuration = controllerConfiguration.DynamicObject; } } public dynamic Configuration { get; private set; } } And used it like this ...public class MyController : BaseController { static readonly string DefaultDetailTimeout = TimeSpan.MaxValue.ToString(); public MyController() { this.DetailTimeout = TimeSpan.Parse(this.Configuration.Detail.Timeout ?? DefaultDetailTimeout); } public TimeSpan DetailTimeout { get; private set; } } And there I have an actual use for the dynamic keyword ... never thoguht I'd see the day when I first heard of it as I don't do much COM work ... oh dont' forget this little helper extension methods to find the controller configuration by the controller type.public static ControllerConfigurationElement ForType<T>(this ControllerConfigurationElementCollection collection) { Contract.Requires(collection != null); return ForType(collection, typeof(T)); } public static ControllerConfigurationElement ForType(this ControllerConfigurationElementCollection collection, Type type) { Contract.Requires(collection != null); Contract.Requires(type != null); return collection.Cast<ControllerConfigurationElement>().Where(element => element.Type == type).SingleOrDefault(); } Sure, it isn't perfect and I'm sure I can tweak it over time, but I thought it was a pretty cool way to take advantage of the dynamic keyword functionality. Just remember, it only validates you did it right at runtime, which isn't that bad ... is it? And yes, I did make it case-insensitive so my code didn't have to look like my XML objects, tweak it to your liking if you dare to use this creation.

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• Vertical Scrolling In Tile Based XNA Platformer

  - by alec100_94

  I'm making a 2D platformer in XNA 4.0. I have created a working tile engine, which works well for my purposes, and Horizontal Scrolling works flawlessly, however I am having great trouble with Vertical scrolling. I Basically want the camera to scroll up (world to scroll down) when the player reaches a certain Y co-ordinate, and I would also like to automatically scroll back down if coming down, and that co-ordinate is passed. My biggest problem is I have no real way of detecting the direction the player is moving in using only the Y Co-ord. Here Is My Code Code For The Camera Class (which appears to be a very different approach to most camera classes I have seen). using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; namespace Marvin { class Camera : TileEngine { public static bool startReached; public static bool endReached; public static void MoveRight(float speed = 2) { //Moves The Position of Each Tile Right foreach (Tile t in tiles) { if(t!=null) { t.position.X -= speed; } } } public static void MoveLeft(float speed = 2) { //Moves The Position of Each Tile Right foreach (Tile t in tiles) { if(t!=null) { t.position.X += speed; } } } public static void MoveUp(float speed = 2) { foreach (Tile t in tiles) { if(t!=null) { t.position.Y += speed; } } } public static void MoveDown(float speed = 2) { foreach (Tile t in tiles) { if(t!=null) { t.position.Y -= speed; } } } public static void Restrain() { if(tiles.Last().position.X<Main.graphics.PreferredBackBufferWidth-tiles.Last().size.X) { MoveLeft(); endReached = true; } else { endReached = false; } if(tiles[1].position.X>0) { MoveRight(); startReached = true;} else { startReached = false; } } } } Here is My Player Code for Left and Right Scrolling/Moving if (Main.currentKeyState.IsKeyDown(Keys.Right)) { Camera.MoveRight(); if(Camera.endReached) { MoveRight(2); } else { if(marvin.GetRectangle().X!=Main.graphics.PreferredBackBufferWidth-(marvin.GetRectangle().X+marvin.GetRectangle().Width)) { MoveRight(2); Camera.MoveLeft(); } } } if(Main.currentKeyState.IsKeyDown(Keys.Left)) { Camera.MoveLeft(); if(Camera.startReached) { MoveLeft(2); } else { if(marvin.GetRectangle().X!=Main.graphics.PreferredBackBufferWidth-(marvin.GetRectangle().X+marvin.GetRectangle().Width)) { MoveLeft(2); Camera.MoveRight(); } } } Camera.Restrain(); if(marvin.GetRectangle().X>Main.graphics.PreferredBackBufferWidth-marvin.GetRectangle().Width) { MoveLeft(2); } if(marvin.GetRectangle().X<0) { MoveRight(2); } And Here Is My Player Jumping/Falling Code which may cause some conflicts with the vertical camera movement. if (!jumping) { if(!TileEngine.TopOfTileCollidingWith(footBounds)) { MoveDown(5); } else { if(marvin.GetRectangle().Y != TileEngine.LastPlatformStoodOnTop()-marvin.GetRectangle().Height) { float difference = (TileEngine.LastPlatformStoodOnTop()-marvin.GetRectangle().Height) - (marvin.GetRectangle().Y); marvin.SetRectangle(marvin.GetRectangle().X,(int)(marvin.GetRectangle().Y+difference)); armR.SetRectangle(armR.GetRectangle().X,(int)(armR.GetRectangle().Y+difference)); armL.SetRectangle(armL.GetRectangle().X,(int)(armL.GetRectangle().Y+difference)); eyeL.SetRectangle(eyeL.GetRectangle().X,(int)(eyeL.GetRectangle().Y+difference)); eyeR.SetRectangle(eyeR.GetRectangle().X,(int)(eyeR.GetRectangle().Y+difference)); } } } if (Main.currentKeyState.IsKeyDown(Keys.Up) && Main.previousKeyState.IsKeyUp(Keys.Up) && TileEngine.TopOfTileCollidingWith(footBounds)) { jumping = true; } if(jumping) { if(TileEngine.LastPlatformStoodOnTop()>0 && (TileEngine.LastPlatformStoodOnTop() - footBounds.Bottom)<120) { MoveUp(5); } else { jumping = false; } } All player code I have tried for vertical movements has failed, or caused weird results (like falling through platforms), and most have been a variation on the method I described above, hence I have not included it. I would really appreciate some help implementing a simple vertical scrolling into this game, Thanks.

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• What are the disadvantages of self-encapsulation?

  - by Dave Jarvis

  Background Tony Hoare's billion dollar mistake was the invention of null. Subsequently, a lot of code has become riddled with null pointer exceptions (segfaults) when software developers try to use (dereference) uninitialized variables. In 1989, Wirfs-Brock and Wikerson wrote: Direct references to variables severely limit the ability of programmers to re?ne existing classes. The programming conventions described here structure the use of variables to promote reusable designs. We encourage users of all object-oriented languages to follow these conventions. Additionally, we strongly urge designers of object-oriented languages to consider the effects of unrestricted variable references on reusability. Problem A lot of software, especially in Java, but likely in C# and C++, often uses the following pattern: public class SomeClass { private String someAttribute; public SomeClass() { this.someAttribute = "Some Value"; } public void someMethod() { if( this.someAttribute.equals( "Some Value" ) ) { // do something... } } public void setAttribute( String s ) { this.someAttribute = s; } public String getAttribute() { return this.someAttribute; } } Sometimes a band-aid solution is used by checking for null throughout the code base: public void someMethod() { assert this.someAttribute != null; if( this.someAttribute.equals( "Some Value" ) ) { // do something... } } public void anotherMethod() { assert this.someAttribute != null; if( this.someAttribute.equals( "Some Default Value" ) ) { // do something... } } The band-aid does not always avoid the null pointer problem: a race condition exists. The race condition is mitigated using: public void anotherMethod() { String someAttribute = this.someAttribute; assert someAttribute != null; if( someAttribute.equals( "Some Default Value" ) ) { // do something... } } Yet that requires two statements (assignment to local copy and check for null) every time a class-scoped variable is used to ensure it is valid. Self-Encapsulation Ken Auer's Reusability Through Self-Encapsulation (Pattern Languages of Program Design, Addison Wesley, New York, pp. 505-516, 1994) advocated self-encapsulation combined with lazy initialization. The result, in Java, would resemble: public class SomeClass { private String someAttribute; public SomeClass() { setAttribute( "Some Value" ); } public void someMethod() { if( getAttribute().equals( "Some Value" ) ) { // do something... } } public void setAttribute( String s ) { this.someAttribute = s; } public String getAttribute() { String someAttribute = this.someAttribute; if( someAttribute == null ) { setAttribute( createDefaultValue() ); } return someAttribute; } protected String createDefaultValue() { return "Some Default Value"; } } All duplicate checks for null are superfluous: getAttribute() ensures the value is never null at a single location within the containing class. Efficiency arguments should be fairly moot -- modern compilers and virtual machines can inline the code when possible. As long as variables are never referenced directly, this also allows for proper application of the Open-Closed Principle. Question What are the disadvantages of self-encapsulation, if any? (Ideally, I would like to see references to studies that contrast the robustness of similarly complex systems that use and don't use self-encapsulation, as this strikes me as a fairly straightforward testable hypothesis.)

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• Is there a theory for "transactional" sequences of failing and no-fail actions?

  - by Ross Bencina

  My question is about writing transaction-like functions that execute sequences of actions, some of which may fail. It is related to the general C++ principle "destructors can't throw," no-fail property, and maybe also with multi-phase transactions or exception safety. However, I'm thinking about it in language-neutral terms. My concern is with correctly designing error handling in C++ functions that must be reliable. I would like to know what the concepts below are called so that I can learn more about them. I'm sorry that I can't ask the question more directly. Since I don't know this area I have provided an example to explain my question. The question is at the end. Here goes: Consider a sequence of steps or actions executed sequentially, where actions belong to one of two classes: those that always succeed, and those that may fail. In the examples below: S stands for an action that always succeeds (called "no-fail" in some settings). F stands for an action that may fail (for example, it might fail to allocate memory or do I/O that could fail). Consider a sequences of actions (executed sequentially from left to right): S->S->S->S Since each action in the sequence above succeeds, the whole sequence succeeds. On the other hand, the following sequence may fail because the last action may fail: S->S->S->F So, claim: a sequence has the no-fail (S) property if and only if all of its actions are no-fail. Now, I'm interested in action sequences that form "atomic transactions", with "failure atomicity," i.e. where either the whole sequence completes successfully, or there is no effect. I.e. if some action fails, the earlier ones must be rolled back. This requires that any successfully executed actions prior to a failing action must always be able to be rolled back. Consider the sequence: S->S->S->F S<-S<-S In the example above, the first row is the forward path of the transaction, and the second row are inverse actions (executed from right to left) that can be used to roll back if the final top row actions fails. It seems to me that for a transaction to support failure atomicity, the following invariant must hold: Claim: To support failure atomicity (either completion or complete roll-back on failure) all actions preceding the latest failable (F) action on the forward path (marked * in the example below) must have no-fail (S) inverses. The following is an example of a sequence that supports failure atomicity: * S->F->F->F S<-S<-S Further, if we want the transaction to be able to attempt cancellation mid-way through, but still guarantee either full completion or full rollback then we need the following property: Claim: To support failure atomicity and cancellation mid-way through execution, in the face of errors in the inverse (cancellation) path, all actions following the earliest failable (F) inverse on the reverse path (marked *) must be no-fail (S). F->F->F->S->S S<-S<-F<-F * I believe that these two conditions guarantee that an abortable/cancelable transaction will never get "stuck". My questions are: What is the study and theory of these properties called? are my claims correct? and what else is there to know? UPDATE 1: Updated terminology: what I previously called "robustness" is called atomicity in the database literature. UPDATE 2: Added explicit reference to failure atomicity, which seems to be a thing.

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• WebLogic Server Performance and Tuning: Part II - Thread Management

  - by Gokhan Gungor

  WebLogic Server, like any other java application server, provides resources so that your applications use them to provide services. Unfortunately none of these resources are unlimited and they must be managed carefully. One of these resources is threads which are pooled to provide better throughput and performance along with the fast response time and to avoid deadlocks. Threads are execution points that WebLogic Server delivers its power and execute work. Managing threads is very important because it may affect the overall performance of the entire system. In previous releases of WebLogic Server 9.0 we had multiple execute queues and user defined thread pools. There were different queues for different type of work which had fixed number of execute threads.  Tuning of this thread pools and finding the proper number of threads was time consuming which required many trials. WebLogic Server 9.0 and the following releases use a single thread pool and a single priority-based execute queue. All type of work is executed in this single thread pool. Its size (thread count) is automatically decreased or increased (self-tuned). The new “self-tuning” system simplifies getting the proper number of threads and utilizing them.Work manager allows your applications to run concurrently in multiple threads. Work manager is a mechanism that allows you to manage and utilize threads and create rules/guidelines to follow when assigning requests to threads. We can set a scheduling guideline or priority a request with a work manager and then associate this work manager with one or more applications. At run-time, WebLogic Server uses these guidelines to assign pending work/requests to execution threads. The position of a request in the execute queue is determined by its priority. There is a default work manager that is provided. The default work manager should be sufficient for most applications. However there can be cases you want to change this default configuration. Your application(s) may be providing services that need mixture of fast response time and long running processes like batch updates. However wrong configuration of work managers can lead a performance penalty while expecting improvement.We can define/configure work managers at;•    Domain Level: config.xml•    Application Level: weblogic-application.xml •    Component Level: weblogic-ejb-jar.xml or weblogic.xml(For a specific web application use weblogic.xml)We can use the following predefined rules/constraints to manage the work;•    Fair Share Request Class: Specifies the average thread-use time required to process requests. The default is 50.•    Response Time Request Class: Specifies a response time goal in milliseconds.•    Context Request Class: Assigns request classes to requests based on context information.•    Min Threads Constraint: Limits the number of concurrent threads executing requests.•    Max Threads Constraint: Guarantees the number of threads the server will allocate to requests.•    Capacity Constraint: Causes the server to reject requests only when it has reached its capacity. Let’s create a work manager for our application for a long running work.Go to WebLogic console and select Environment | Work Managers from the domain structure tree. Click New button and select Work manager and click next. Enter the name for the work manager and click next. Then select the managed server instances(s) or clusters from available targets (the one that your long running application is deployed) and finish. Click on MyWorkManager, and open the Configuration tab and check Ignore Stuck Threads and save. This will prevent WebLogic to tread long running processes (that is taking more than a specified time) as stuck and enable to finish the process.

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• Syntax of passing lambda

  - by Astara

  Right now, I'm working on refactoring a program that calls its parts by polling to a more event-driven structure. I've created sched and task classes with the sced to become a base class of the current main loop. The tasks will be created for each meter so they can be called off of that instead of polling. Each of the events main calls are a type of meter that gather info and display it. When the program is coming up, all enabled meters get 'constructed' by a main-sub. In that sub, I want to store off the "this" pointer associated with the meter, as well as the common name for the "action routine. void MeterMaker::Meter_n_Task (Meter * newmeter,) { push(newmeter); // handle non-timed draw events Task t = new Task(now() + 0.5L); t.period={0,1U}; t.work_meter = newmeter; t.work = [&newmeter](){newmeter.checkevent();};<<--attempt at lambda t.flags = T_Repeat; t.enable_task(); _xos->sched_insert(t); } A sample call to it: Meter_n_Task(new CPUMeter(_xos, "CPU ")); 've made the scheduler a base class of the main routine (that handles the loop), and I've tried serveral variations to get the task class to be a base of the meter class, but keep running into roadblocks. It's alot like "whack-a-mole" -- pound in something to fix something one place, and then a new probl pops out elsewhere. Part of the problem, is that the sched.h file that is trying to hold the Task Q, includes the Task header file. The task file Wants to refer to the most "base", Meter class. The meter class pulls in the main class of the parent as it passes a copy of the parent to the children so they can access the draw routines in the parent. Two references in the task file are for the 'this' pointer of the meter and the meter's update sub (to be called via this). void *this_data= NULL; void (*this_func)() = NULL; Note -- I didn't really want to store these in the class, as I wanted to use a lamdba in that meter&task routine above to store a routine+context to be used to call the meter's action routine. Couldn't figure out the syntax. But am running into other syntax problems trying to store the pointers...such as g++: COMPILE lsched.cc In file included from meter.h:13:0, from ltask.h:17, from lsched.h:13, from lsched.cc:13: xosview.h:30:47: error: expected class-name before ‘{’ token class XOSView : public XWin, public Scheduler { Like above where it asks for a class, where the classname "Scheduler" is. !?!? Huh? That IS a class name. I keep going in circles with things that don't make sense... Ideally I'd get the lamba to work right in the Meter_n_Task routine at the top. I wanted to only store 1 pointer in the 'Task' class that was a pointer to my lambda that would have already captured the "this" value ... but couldn't get that syntax to work at all when I tried to start it into a var in the 'Task' class. This project, FWIW, is my teething project on the new C++... (of course it's simple!.. ;-))... I've made quite a bit of progress in other areas in the code, but this lambda syntax has me stumped...its at times like thse that I appreciate the ease of this type of operation in perl. Sigh. Not sure the best way to ask for help here, as this isn't a simple question. But thought I'd try!... ;-) Too bad I can't attach files to this Q.

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• How to deploy global managed beans

  - by frank.nimphius

  v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} "Global managed" beans is the term I use in this post to describe beans that are used across applications. Global managed beans contain helper - or utility - methods like or instead of JSFUtils and ADFUtils. The difference between global managed beans and static helper classes like JSFUtis and ADFUtils is that they are EL accessible, providing reusable functionality that is ready to use on UI components and - if accessed from Java - in other managed beans. For example, the ADF Faces page template (af:pageTemplate) allows you to define attributes for the consuming page to pass in object references or strings into it. It does not have method attributes that allow command components contained in a template to invoke listeners in managed beans and the ADF binding layer, or to execute actions. To create templates that provide global button or menu functionality, like logon, logout, print etc., an option for developers is to deployed managed beans with the ADF Faces page templates. To deploy a managed bean with a page template, create an ADF library from the project containing the template definition and import this ADF library into the target project using the Resource palette. When importing an ADF library, all its content is added to the project, including page template definitions, managed bean sources and configurations. More about page templates http://download.oracle.com/docs/cd/E17904_01/apirefs.1111/e12419/tagdoc/af_pageTemplate.html Another use-case for globally configured managed beans is for creating helper methods to be used in many applications. Instead of creating a base managed bean class that then is extended by all managed beans used in applications, you can deploy a managed bean in a JAR file and add the faces-config.xml file with the managed bean configuration to the JAR's META-INF folder as shown below. Using a globally configured managed bean allows you to use Expression Language in the UI to access common functionality but also use Java in application specific managed beans. Storing the faces-config.xml file in the JAR file META-INF directory automatically makes it available when the JAR file is found in the class path of an application.

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• Part 6: Extensions vs. Modifications

  - by volker.eckardt(at)oracle.com

  Customizations = Extensions + Modifications In the EBS terminology, a customization can be an extension or a modification. Extension means that you mainly create your own code from scratch. You may utilize existing views, packages and java classes, but your code is unique. Modifications are quite different, because here you take existing code and change or enhance certain areas to achieve a slightly different behavior. Important is that it doesn't matter if you place your code at the same or at another place – it is a modification. It is also not relevant if you leave the original code enabled or not! Why? Here is the answer: In case the original code piece you have taken as your base will get patched, you need to copy the source again and apply all your changes once more. If you don't do that, you may get different results or write different data compared to the standard – this causes a high risk! Here are some guidelines how to reduce the risk: Invest a bit longer when searching for objects to select data from. Rather choose a view than a table. In case Oracle development changes the underlying tables, the view will be more stable and is therefore a better choice. Choose rather public APIs over internal APIs. Same background as before: although internal structure might change, the public API is more stable. Use personalization and substitution rather than modification. Spend more time to check if the requirement can be covered with such techniques. Build a project code library, avoid that colleagues creating similar functionality multiple times. Otherwise you have to review lots of similar code to determine the need for correction. Use the technique of “flagged files”. Flagged files is a way to mark a standard deployment file. If you run the patch analyse (within Application Manager), the analyse result will list flagged standard files in case they will be patched. If you maintain a cross reference to your own CEMLIs, you can easily determine which CEMLIs have to be reviewed. Implement a code review process. This can be done by utilizing team internal or external persons. If you implement such a team internal process, your team members will come up with suggestions how to improve the code quality by themselves. Review heavy customizations regularly, to identify options to reduce complexity; let's say perform this every 6th month. You may not spend days for such a review, but a high level cross check if the customization can be reduced is suggested. De-install customizations which are no more required. Define a process for this. Add a section into the technical documentation how to uninstall and what are possible implications. Maintain a cross reference between CEMLIs and between CEMLIs, EBS modules and business processes. Keep this list up to date! Share this list! By following these guidelines, you are able to improve product stability. Although we might not be able to avoid modifications completely, we can give a much better advise to developers and to our test team. Summary: Extensions and Modifications have to be handled differently during their lifecycle. Modifications implicate a much higher risk and should therefore be reviewed more frequently. Good cross references allow you to give clear advise for the testing activities.

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• A Reusable Builder Class for .NET testing

  - by Liam McLennan

  When writing tests, other than end-to-end integration tests, we often need to construct test data objects. Of course this can be done using the class’s constructor and manually configuring the object, but to get many objects into a valid state soon becomes a large percentage of the testing effort. After many years of painstakingly creating builders for each of my domain objects I have finally become lazy enough to bother to write a generic, reusable builder class for .NET. To use it you instantiate a instance of the builder and configuring it with a builder method for each class you wish it to be able to build. The builder method should require no parameters and should return a new instance of the type in a default, valid state. In other words the builder method should be a Func<TypeToBeBuilt>. The best way to make this clear is with an example. In my application I have the following domain classes that I want to be able to use in my tests: public class Person { public string Name { get; set; } public int Age { get; set; } public bool IsAndroid { get; set; } } public class Building { public string Street { get; set; } public Person Manager { get; set; } } The builder for this domain is created like so: build = new Builder(); build.Configure(new Dictionary<Type, Func<object>> { {typeof(Building), () => new Building {Street = "Queen St", Manager = build.A<Person>()}}, {typeof(Person), () => new Person {Name = "Eugene", Age = 21}} }); Note how Building depends on Person, even though the person builder method is not defined yet. Now in a test I can retrieve a valid object from the builder: var person = build.A<Person>(); If I need a class in a customised state I can supply an Action<TypeToBeBuilt> to mutate the object post construction: var person = build.A<Person>(p => p.Age = 99); The power and efficiency of this approach becomes apparent when your tests require larger and more complex objects than Person and Building. When I get some time I intend to implement the same functionality in Javascript and Ruby. Here is the full source of the Builder class: public class Builder { private Dictionary<Type, Func<object>> defaults; public void Configure(Dictionary<Type, Func<object>> defaults) { this.defaults = defaults; } public T A<T>() { if (!defaults.ContainsKey(typeof(T))) throw new ArgumentException("No object of type " + typeof(T).Name + " has been configured with the builder."); T o = (T)defaults[typeof(T)](); return o; } public T A<T>(Action<T> customisation) { T o = A<T>(); customisation(o); return o; } }

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• Any tips on getting hired as a software project manager straight out of college?

  - by MHarrison

  I graduated with a BS in compsci last September, and I've been trying (unsuccessfully) to find a job as a project manager ever since. I fell in love with software engineering (the formal practice behind it all, not just coding) in school, and I've dedicated the last 3-4 years of my life to learning everything I can about project management and gaining experience. I've managed several projects (with teams around 12 people) while in school, and I worked with my university's software engineering research lab. My résumé is also decent - I worked as a programmer before I went to school (I'm 27 now), and I did Google Summer of Code for 3 summers. I also have general "people management" experience via working as the photo editor for my university's newspaper for 2 years. My first problem with the job hunt is not getting enough interviews. I use careers.stackoverflow.com, which is awesome because I usually get contacted by non-HR people who know what they're talking about, but there's just not enough companies using it for me to get interviews on a regular basis. I've also tried sites like monster.com, and in a fit of desperation, I sent out no less than 60 applications to project management positions. I've gotten 3 automated rejection letters and that's it. At least careers.stackoverflow gets me a phone interview with 8/10 places I apply to. But the main (and extremely frustrating) problem is the matter of experience. I've successfully managed projects from start to finish (in my software engineering classes we had real customers come in with a real software need and we built it for them), but I've never had to deal with budgets and money (I know this is why HR people immediately turn me away). Most of these positions require 5+ years PM experience, and I've seen absurd things like 12+ years required. Interviews are also maddening. I've had so many places who absolutely loved me and I made it to the final round of interviews, and I left thinking things went extremely well and they'd consider me. However, when I check in with them a week later, they tell me "We really liked you and your qualifications are excellent, but we're hoping to find someone with more experience." The bad interviews I can understand - like the PM position that would have had me managing developers both locally and overseas - I had 3 interviews with them and the ENTIRE interview process was them asking me CS brainteasers and having me waste time on things like writing quicksort on paper or writing binary search trees. Even when I tried steering the discussion towards more relevant PM stuff, they gave me some vague generic replies and went back to the "We want to be Google/MS" crap. But when I have a GOOD interview, they say my "qualifications are excellent" but they want "more experience"...that makes me want to tear my hair out. What else can I DO? While I'm aiming for technically-involved PM positions (not just crunching budget numbers), I really don't want a straight development job because I like creating software from the very high-level vs. spending a lot of time debugging memory leaks. In fact, I can't even GET development positions that I'm qualified for because I make the mistake of telling them that my future career goals are as PM (which usually results in them saying something like "Well we already have PMs and this position isn't really set up to get you there." - which I take to mean "No, that's my job, stay away.") My apologies on the long rant, but I'm seriously hellbent on getting hired as a PM since it's both my career goal and the passion that keeps me awake at night. Any suggestions on what the heck else I can do? I'm currently writing a blog where I talk about my philosophies about software engineering, and I'm writing up specs for an iOS app which I will design, code, and show employers, but this takes an awful lot of time that I don't have.

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• ReSharper 8.0 EAP now available

  - by TATWORTH

  Originally posted on: http://geekswithblogs.net/TATWORTH/archive/2013/06/28/resharper-8.0-eap-now-available.aspxJetbrains have just released |ReSharper 8.0 Beta on their Early Access |Programme at http://www.jetbrains.com/resharper/whatsnew/?utm_source=resharper8b&utm_medium=newsletter&utm_campaign=resharper&utm_content=customersResharper 8.0 comes with the following new features:Support for Visual Studio 2013 Preview. Yes, ReSharper is known to work well with the fresh preview of Visual Studio 2013, and if you have already started digging into it, ReSharper 8.0 Beta is ready for the challenge.Faster code fixes. Thanks to the new Fix in Scope feature, you can choose to batch-fix some of the code issues that ReSharper detects in the scope of a project or the whole solution. Supported fixes include removing unused directives and redundant casts.Project dependency viewer. ReSharper is now able to visualize a project dependency graph for a bird's eye view of dependencies within your solution, all without compiling anything!Multifile templates. ReSharper's file templates can now be expanded to generate more than one file. For instance, this is handy for generating pairs of a main logic class and a class for extensions, or sets of partial files.Navigation improvements. These include a new action called Go to Everything to let you search for a file, type or method name from the same input box; support for line numbers in navigation actions; a new tool window called Assembly Explorer for browsing through assemblies; and two more contextual navigation actions: Navigate to Generic Substitutions and Navigate to Assembly Explorer.New solution-wide refactorings. The set of fresh refactorings is headlined by the highly requested Move Instance Method to move methods between classes without making them static. In addition, there are Inline Parameter and Pull Parameter. Last but not least, we're also introducing 4 new XAML-specific refactorings!Extraordinary XAML support. A plethora of new and improved functionality for all developers working with XAML code includes dedicated grid inspections and quick-fixes; Extract Style, Extract, Move and Inline Resource refactorings; atomic renaming of dependency properties; and a lot more.More accessible code completion. ReSharper 8 makes more of its IntelliSense magic available in automatic completion lists, including extension methods and an option to import a type. We're also introducing double completion which gives you additional completion items when you press the corresponding shortcut for the second time.A new level of extensibility. With the new NuGet-based Extension Manager, discovering, installing and uninstalling ReSharper extensions becomes extremely easy in Visual Studio 2010 and higher. When we say extensions, we mean not only full-fledged plug-ins but also sets of templates or SSR patterns that can now be shared much more easily.CSS support improvements. Smarter usage search for CSS attributes, new CSS-specific code inspections, configurable support for CSS3 and earlier versions, compatibility checks against popular browsers - there's a rough outline of what's new for CSS in ReSharper 8.A command-line version of ReSharper. ReSharper 8 goes beyond Visual Studio: we now provide a free standalone tool with hundreds of ReSharper inspections and additionally a duplicate code finder that you can integrate with your CI server or version control system.Multiple minor improvements in areas such as decompiling and code formatting, as well as support for the Blue Theme introduced in Visual Studio 2012 Update 2.

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• Move on and look elsewhere, or confront the boss?

  - by Meister

  Background: I have my Associates in Applied Science (Comp/Info Tech) with a strong focus in programming, and I'm taking University classes to get my Bachelors. I was recently hired at a local company to be a Software Engineer I on a team of about 8, and I've been told they're looking to hire more. This is my first job, and I was offered what I feel to be an extremely generous starting salary ($30/hr essentially + benefits and yearly bonus). What got me hired was my passion for programming and a strong set of personal projects. Problem: I had no prior experience when I interviewed, so I didn't know exactly what to ask them about the company when I was hired. I've spotted a number of warning signs and annoyances since then, such as: Four developers when I started, with everyone talking about "Ben" or "Ryan" leaving. One engineer hired thirty days before me, one hired two weeks after me. Most of the department has been hiring a large number of people since I started. Extremely limited internet access. I understand the idea from an IT point of view, but not only is Facebook blocked, but so it Youtube, Twitter, and Pandora. I've also figured out that they block all access to non-DNS websites (http://xxx.xxx.xxx.xxx/) and strangely enough Miranda-IM. Low cubicles. Which is fine because I like my immediate coworkers, but they put the developers with the customer service, customer training, and QA department in a huge open room. Noise, noise, noise, and people stop to chitchat all day long. Headphones only go so far. Several emails have been sent out by my boss since I started telling us programmers to not talk about non-work-related-things like Video Games at our cubicles, despite us only spending maybe five minutes every few hours doing so. Further digging tells me that this is because someone keeps complaining that the programmers are "slacking off". People are looking over my shoulder all day. I was in the Freenode webchat to get help with a programming issue, and within minutes I had an email from my boss (to all the developers) telling us that we should NOT be connected to any outside chat servers at work. Version control system from 2005 that we must access with IE and keep the Java 1.4 JRE installed to be able to use. I accidentally updated to Java 6 one day and spent the next two days fighting with my PC to undo this "problem". No source control, no comments on anything, no standards, no code review, no unit testing, no common sense. I literally found a problem in how they handle string resource translations that stems from the simple fact that they don't trim excess white spaces, leading to developers doing: getResource("Date: ") instead of: getResource("Date") + ": ", and I was told to just add the excess white spaces back to the database instead of dealing with the issue directly. Some of these things I'd like to try to understand, but I like having IRC open to talk in a few different rooms during the day and keep in touch with friends/family over IM. They don't break my concentration (not NEARLY as much as the lady from QA stopping by to talk about her son), but because people are looking over my shoulder all day as they walk by they complain when they see something that's not "programmer-looking work". I've been told by my boss and QA that I do good, fast work. I should be judged on my work output and quality, not what I have up on my screen for the five seconds you're walking by So, my question is, even though I'm just barely at my 90 days: How do you decide to move on from a job and looking elsewhere, or when you should start working with your boss to resolve these issues? Is it even possible to get the boss to work with me in many of these things? This is the only place I heard back from even though I sent out several resume's a day for several months, and this place does pay well for putting up with their many flaws, but I'm just starting to get so miserable working here already. Should I just put up with it?

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• Looking for a real-world example illustrating that composition can be superior to inheritance

  - by Job

  I watched a bunch of lectures on Clojure and functional programming by Rich Hickey as well as some of the SICP lectures, and I am sold on many concepts of functional programming. I incorporated some of them into my C# code at a previous job, and luckily it was easy to write C# code in a more functional style. At my new job we use Python and multiple inheritance is all the rage. My co-workers are very smart but they have to produce code fast given the nature of the company. I am learning both the tools and the codebase, but the architecture itself slows me down as well. I have not written the existing class hierarchy (neither would I be able to remember everything about it), and so, when I started adding a fairly small feature, I realized that I had to read a lot of code in the process. At the surface the code is neatly organized and split into small functions/methods and not copy-paste-repetitive, but the flip side of being not repetitive is that there is some magic functionality hidden somewhere in the hierarchy chain that magically glues things together and does work on my behalf, but it is very hard to find and follow. I had to fire up a profiler and run it through several examples and plot the execution graph as well as step through a debugger a few times, search the code for some substring and just read pages at the time. I am pretty sure that once I am done, my resulting code will be short and neatly organized, and yet not very readable. What I write feels declarative, as if I was writing an XML file that drives some other magic engine, except that there is no clear documentation on what the XML should look like and what the engine does except for the existing examples that I can read as well as the source code for the 'engine'. There has got to be a better way. IMO using composition over inheritance can help quite a bit. That way the computation will be linear rather than jumping all over the hierarchy tree. Whenever the functionality does not quite fit into an inheritance model, it will need to be mangled to fit in, or the entire inheritance hierarchy will need to be refactored/rebalanced, sort of like an unbalanced binary tree needs reshuffling from time to time in order to improve the average seek time. As I mentioned before, my co-workers are very smart; they just have been doing things a certain way and probably have an ability to hold a lot of unrelated crap in their head at once. I want to convince them to give composition and functional as opposed to OOP approach a try. To do that, I need to find some very good material. I do not think that a SCIP lecture or one by Rich Hickey will do - I am afraid it will be flagged down as too academic. Then, simple examples of Dog and Frog and AddressBook classes do not really connivence one way or the other - they show how inheritance can be converted to composition but not why it is truly and objectively better. What I am looking for is some real-world example of code that has been written with a lot of inheritance, then hit a wall and re-written in a different style that uses composition. Perhaps there is a blog or a chapter. I am looking for something that can summarize and illustrate the sort of pain that I am going through. I already have been throwing the phrase "composition over inheritance" around, but it was not received as enthusiastically as I had hoped. I do not want to be perceived as a new guy who likes to complain and bash existing code while looking for a perfect approach while not contributing fast enough. At the same time, my gut is convinced that inheritance is often the instrument of evil and I want to show a better way in a near future. Have you stumbled upon any great resources that can help me?

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• JavaOne 2012: Nashorn Edition

  - by $utils.escapeXML($entry.author)

  As with my JavaOne 2012: OpenJDK Edition post a while back (now updated to reflect the schedule of the talks), I find it convenient to have my JavaOne schedule ordered by subjects of interest. Beside OpenJDK in all its flavors, another subject I find very exciting is Nashorn. I blogged about the various material on Nashorn in the past, and we interviewed Jim Laskey, the Project Lead on Project Nashorn in the Java Spotlight podcast. So without further ado, here are the JavaOne 2012 talks and BOFs with Nashorn in their title, or abstract:CON5390 - Nashorn: Optimizing JavaScript and Dynamic Language Execution on the JVM - Monday, Oct 1, 8:30 AM - 9:30 AMThere are many implementations of JavaScript, meant to run either on the JVM or standalone as native code. Both approaches have their respective pros and cons. The Oracle Nashorn JavaScript project is based on the former approach. This presentation goes through the performance work that has gone on in Oracle’s Nashorn JavaScript project to date in order to make JavaScript-to-bytecode generation for execution on the JVM feasible. It shows that the new invoke dynamic bytecode gets us part of the way there but may not quite be enough. What other tricks did the Nashorn project use? The presentation also discusses future directions for increased performance for dynamic languages on the JVM, covering proposed enhancements to both the JVM itself and to the bytecode compiler.CON4082 - Nashorn: JavaScript on the JVM - Monday, Oct 1, 3:00 PM - 4:00 PMThe JavaScript programming language has been experiencing a renaissance of late, driven by the interest in HTML5. Nashorn is a JavaScript engine implemented fully in Java on the JVM. It is based on the Da Vinci Machine (JSR 292) and will be available with JDK 8. This session describes the goals of Project Nashorn, gives a top-level view of how it all works, provides the current status, and demonstrates examples of JavaScript and Java working together.BOF4763 - Meet the Nashorn JavaScript Team - Tuesday, Oct 2, 4:30 PM - 5:15 PMCome to this session to meet the Oracle JavaScript (Project Nashorn) language teamBOF6661 - Nashorn, Node, and Java Persistence - Tuesday, Oct 2, 5:30 PM - 6:15 PMWith Project Nashorn, developers will have a full and modern JavaScript engine available on the JVM. In addition, they will have support for running Node applications with Node.jar. This unique combination of capabilities opens the door for best-of-breed applications combining Node with Java SE and Java EE. In this session, you’ll learn about Node.jar and how it can be combined with Java EE components such as EclipseLink JPA for rich Java persistence. You’ll also hear about all of Node.jar’s mapping, caching, querying, performance, and scaling features.CON10657 - The Polyglot Java VM and Java Middleware - Thursday, Oct 4, 12:30 PM - 1:30 PMIn this session, Red Hat and Oracle discuss the impact of polyglot programming from their own unique perspectives, examining non-Java languages that utilize Oracle’s Java HotSpot VM. You’ll hear a discussion of topics relating to Ruby, Lisp, and Clojure and the intersection of other languages where they may touch upon individual frameworks and projects, and you’ll get perspectives on JavaScript via the Nashorn Project, an upcoming JavaScript engine, developed fully in Java.CON5251 - Putting the Metaobject Protocol to Work: Nashorn’s Java Bindings - Thursday, Oct 4, 2:00 PM - 3:00 PMProject Nashorn is Oracle’s new JavaScript runtime in Java 8. Being a JavaScript runtime running on the JVM, it provides integration with the underlying runtime by enabling JavaScript objects to manipulate Java objects, implement Java interfaces, and extend Java classes. Nashorn is invokedynamic-based, and for its Java integration, it does away with the concept of wrapper objects in favor of direct virtual machine linking to Java objects’ methods provided by a metaobject protocol, providing much higher performance than what could be expected from a scripting runtime. This session looks at the details of the integration, a topic of interest to other language implementers on the JVM and a wider audience of developers who want to understand how Nashorn works.That's 6 sessions tooting the Nashorn this year at JavaOne, up from 2 last year.

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• Syntax of passing lambda causing hair loss (pulling out)

  - by Astara

  Right now, I'm working on refactoring a program that calls its parts by polling to a more event-driven structure. I've created sched and task classes with the sced to become a base class of the current main loop. The tasks will be created for each meter so they can be called off of that instead of polling. Each of the events main calls are a type of meter that gather info and display it. When the program is coming up, all enabled meters get 'constructed' by a main-sub. In that sub, I want to store off the "this" pointer associated with the meter, as well as the common name for the "action routine. void MeterMaker::Meter_n_Task (Meter * newmeter,) { push(newmeter); // handle non-timed draw events Task t = new Task(now() + 0.5L); t.period={0,1U}; t.work_meter = newmeter; t.work = [&newmeter](){newmeter.checkevent();};<<--attempt at lambda t.flags = T_Repeat; t.enable_task(); _xos->sched_insert(t); } A sample call to it: Meter_n_Task(new CPUMeter(_xos, "CPU ")); 've made the scheduler a base class of the main routine (that handles the loop), and I've tried serveral variations to get the task class to be a base of the meter class, but keep running into roadblocks. It's alot like "whack-a-mole" -- pound in something to fix something one place, and then a new probl pops out elsewhere. Part of the problem, is that the sched.h file that is trying to hold the Task Q, includes the Task header file. The task file Wants to refer to the most "base", Meter class. The meter class pulls in the main class of the parent as it passes a copy of the parent to the children so they can access the draw routines in the parent. Two references in the task file are for the 'this' pointer of the meter and the meter's update sub (to be called via this). void *this_data= NULL; void (*this_func)() = NULL; Note -- I didn't really want to store these in the class, as I wanted to use a lamdba in that meter&task routine above to store a routine+context to be used to call the meter's action routine. Couldn't figure out the syntax. But am running into other syntax problems trying to store the pointers...such as g++: COMPILE lsched.cc In file included from meter.h:13:0, from ltask.h:17, from lsched.h:13, from lsched.cc:13: xosview.h:30:47: error: expected class-name before ‘{’ token class XOSView : public XWin, public Scheduler { Like above where it asks for a class, where the classname "Scheduler" is. !?!? Huh? That IS a class name. I keep going in circles with things that don't make sense... Ideally I'd get the lamba to work right in the Meter_n_Task routine at the top. I wanted to only store 1 pointer in the 'Task' class that was a pointer to my lambda that would have already captured the "this" value ... but couldn't get that syntax to work at all when I tried to start it into a var in the 'Task' class. This project, FWIW, is my teething project on the new C++... (of course it's simple!.. ;-))... I've made quite a bit of progress in other areas in the code, but this lambda syntax has me stumped...its at times like thse that I appreciate the ease of this type of operation in perl. Sigh. Not sure the best way to ask for help here, as this isn't a simple question. But thought I'd try!... ;-) Too bad I can't attach files to this Q.

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• Patterns for a tree of persistent data with multiple storage options?

  - by Robin Winslow

  I have a real-world problem which I'll try to abstract into an illustrative example. So imagine I have data objects in a tree, where parent objects can access children, and children can access parents: // Interfaces interface IParent<TChild> { List<TChild> Children; } interface IChild<TParent> { TParent Parent; } // Classes class Top : IParent<Middle> {} class Middle : IParent<Bottom>, IChild<Top> {} class Bottom : IChild<Middle> {} // Usage var top = new Top(); var middles = top.Children; // List<Middle> foreach (var middle in middles) { var bottoms = middle.Children; // List<Bottom> foreach (var bottom in bottoms) { var middle = bottom.Parent; // Access the parent var top = middle.Parent; // Access the grandparent } } All three data objects have properties that are persisted in two data stores (e.g. a database and a web service), and they need to reflect and synchronise with the stores. Some objects only request from the web service, some only write to it. Data Mapper My favourite pattern for data access is Data Mapper, because it completely separates the data objects themselves from the communication with the data store: class TopMapper { public Top FetchById(int id) { var top = new Top(DataStore.TopDataById(id)); top.Children = MiddleMapper.FetchForTop(Top); return Top; } } class MiddleMapper { public Middle FetchById(int id) { var middle = new Middle(DataStore.MiddleDataById(id)); middle.Parent = TopMapper.FetchForMiddle(middle); middle.Children = BottomMapper.FetchForMiddle(bottom); return middle; } } This way I can have one mapper per data store, and build the object from the mapper I want, and then save it back using the mapper I want. There is a circular reference here, but I guess that's not a problem because most languages can just store memory references to the objects, so there won't actually be infinite data. The problem with this is that every time I want to construct a new Top, Middle or Bottom, it needs to build the entire object tree within that object's Parent or Children property, with all the data store requests and memory usage that that entails. And in real life my tree is much bigger than the one represented here, so that's a problem. Requests in the object In this the objects request their Parents and Children themselves: class Middle { private List<Bottom> _children = null; // cache public List<Bottom> Children { get { _children = _children ?? BottomMapper.FetchForMiddle(this); return _children; } set { BottomMapper.UpdateForMiddle(this, value); _children = value; } } } I think this is an example of the repository pattern. Is that correct? This solution seems neat - the data only gets requested from the data store when you need it, and thereafter it's stored in the object if you want to request it again, avoiding a further request. However, I have two different data sources. There's a database, but there's also a web service, and I need to be able to create an object from the web service and save it back to the database and then request it again from the database and update the web service. This also makes me uneasy because the data objects themselves are no longer ignorant of the data source. We've introduced a new dependency, not to mention a circular dependency, making it harder to test. And the objects now mask their communication with the database. Other solutions Are there any other solutions which could take care of the multiple stores problem but also mean that I don't need to build / request all the data every time?

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• Applying for internship

  - by Margus

  At the moment I'm thinking about applying for internship at Eesti Energia. I seem to be eligible, but before contacting them I need to learn how to compile an informative and complete CV and cover letter. I do not consider myself as shallow minded, but also I'm not sure how to convincingly justify the stand of interest and how internship will help me in my future career. Course of life Tallinna Tehnikagümnaasium 2003 - 2006 Tallinna Tehnikaülikool 2006 – 2009 Military service at Signal Batallion Tallinna Tehnikaülikool 2010 – ... I started my academic career as Computer and Systems Engineer, but as I excelled in programming classes, I changed my major to Software Engineer and taken my specialty in web applications and logic. Nowadays I mainly use Java, Mathematica and C# to solve problems. For 2 times, I have taken part in ACM International Collegiate Programming Contest, where my team won the nationals and did pretty well in Europe. Also as part of notable thing in my academic career, my team wrote the Kalah game AI, that won in University's main programming class AI tournament. My hobbies are mind games and occasional problem solving. Few years ago I also competed in International Checkers EM (requires being in top 3 in nationals) as part of cadet and junior age group - I did not come close to winning, but I exceeded about half of the players each time. In high school and gymnasium I took part and later was the captain of team, that passes regionals and made it to top 3 of nationals (and later won) in (blitz) russian checkers. That was impressive because, it was a team effort as we only had (depending on year) 2-3 strong players. Although I started programming exactly 9,5 years ago I have no work experience. Well actually thats not true, as I completed my army duty, I was hired for a year (days still counting) to be apart of communicational (emergency) infrastructure action group where I'm the teams IT specialist (it's more complicated). So I consider myself to be aware of: rough conditions, teamwork, high stress tolerance, being on time and what responsibility means. As negative things I can mention: I do not have drivers licence. Although only Estonian and English are noted as requirements, then Russian is most likely required as well and I barely understand some of it. Reasons why I want to apply there, are: I need to do at least 4-6 week traineeship and it's in the right field I have the requirements and tasks seem easy enough Company is well known and has fairly good reputation Family and friend think, that it would be acceptable place to work Myriad of options to do final thesis about open up Work place is located in the same city I live atm. At moment, I see myself having a hard time explain why I would prefer it or where I see myself in 10 years if I was offered a job there. Question I have some idea how Curriculum Vitæ should look like, or I can google for template, but I'm not sure how to write informative one. Last I did one, it looked like: picture + contact information + education. Vaguely I only remember, that cover letter should be custom tailored for each place you apply containing ...

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• GameStateManagement and inputs not being recognized

  - by Dave Voyles

  EDIT: I've removed a bit of code from the input class to make this more readable, and updated my StartScreen class, which is now at the bottom. I have the same issues though, but they are explained in my comments on the bottom of this page. It won't let me paste my additional code here (the format comes out crazy), so I've linked to pastebin with the code pastebin I've been trying to implement the MS provided GameStateManagement sample with my game, but it has proven a bit difficult. Really, I'm using Oneksoft's Starter Kit, which uses the MS provided sample, so they are identical, except for my splash screen. I'm able to get the splash screen to launch, where it informs the player to press A to advance the screen, but this doesn't seem to accept any of my inputs. I’ve also added Console.Writeline(“Pressing A”) under the IsMenuPressed method in Input.cs to verify that it is getting called, but for some reason it is constantly spamming my log, rather than just appearing each time I press it. Not sure why this is happening. I have a bit too much code to post it all here, so I’ve attached a link to my .rar with my classes, but I’ll also leave a bit here which I thinkmay be applicable. https://www.dropbox.com/sh/6ek4uru2jc2ch0k/JTeBWN_3PQ What do you guys think the issue is? namespace Pong { public class Input { public const int MaxInputs = 4; public readonly KeyboardState[] CurrentKeyboardState; public readonly GamePadState[] CurrentGamePadState; public KeyboardState[] LastKeyboardState; public GamePadState[] LastGamePadState; public readonly bool[] GamePadWasConnected; public Input() { // Get input state CurrentKeyboardState = new KeyboardState[MaxInputs]; CurrentGamePadState = new GamePadState[MaxInputs]; // Preserving last states to check for isKeyUp events LastKeyboardState = CurrentKeyboardState; LastGamePadState = CurrentGamePadState; } /// <summary> /// Checks for a "menu select" input action. /// The controllingPlayer parameter specifies which player to read input for. /// If this is null, it will accept input from any player. When the action /// is detected, the output playerIndex reports which player pressed it. /// </summary> public bool IsMenuSelect(PlayerIndex? controllingPlayer, out PlayerIndex playerIndex) { Console.WriteLine("Pressing A"); return IsNewKeyPress(Keys.Space, controllingPlayer, out playerIndex) || IsNewKeyPress(Keys.Enter, controllingPlayer, out playerIndex) || IsNewButtonPress(Buttons.A, controllingPlayer, out playerIndex) || IsNewButtonPress(Buttons.Start, controllingPlayer, out playerIndex); } /// <summary> /// Checks for a "menu cancel" input action. /// The controllingPlayer parameter specifies which player to read input for. /// If this is null, it will accept input from any player. When the action /// is detected, the output playerIndex reports which player pressed it. /// </summary> public bool IsMenuCancel(PlayerIndex? controllingPlayer, out PlayerIndex playerIndex) { return IsNewKeyPress(Keys.Escape, controllingPlayer, out playerIndex) || IsNewButtonPress(Buttons.B, controllingPlayer, out playerIndex) || IsNewButtonPress(Buttons.Back, controllingPlayer, out playerIndex); }

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• Can you/should you develop components for ASP.NET MVC?

  - by Vilx-

  Following from the previous question I've started to wonder - is it possible to implement "Components" in ASP.NET MVC (latest version)? And should you? Let's clarify what I mean with a "component". With that I mean a "control" (aka "widget"), similar to those that ASP.NET webforms is built upon. A gridview might be a good example. In webforms I can place on my form a datasource component (one line of code), a gridview component (another line of code) and bind them together (specify an attribute on the gridview). In the codebehind file I fill the datasource with data (a few lines of DB-querying code), and I'm all set. At this point the gridview is a fully functional standalone component. I can open the form, and I'll see all the data. I can sort it by clicking on the column headers; it is split into several pages; I can drag the column headers around and rearrange columns; I can turn on "grouping" mode; etc. And I don't need to write another line of code for any of it. The gridview, as a component, already has all the code tucked away in its classes and assemblies. I just place it on the form, initialize it, and it Just Works. At some times (like sorting or navigation to a different page) it will also perform ajax callbacks to the server, but those too will be handled internally, with my code having no knowledge at all about it. And then there are also events that I can attach if I want to get notified when something happens. In MVC I cannot see a way of doing this cleanly. Sure, there are the partial views, but those only handle half of the problem - they render the initial HTML. Some more can be achieved with client-side Javascript (like column re-arranging), but when the grid needs to do an ajax callback (say, to fetch the next page of data), my code will have to get involved and process that request. At best I guess I can provide some helper methods to process it, but I'll have to write the code that calls them, and also provide a controller method with signature matching the arguments of that callback. I guess that I could make some hacks with global events or special routes or something, but that just seems... hackish. Unelegant. Perhaps this is not the MVC way? Although I've completed one project in it, I'm still far from being an MVC expert. But then what is? In the intranet application that we're building there are dozens upon dozens of such grids. Naturally I want them all to have a unified look & behavior, and I don't want to repeat the same code all over the place. So what's the "MVC" approach to this problem?

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• Custom Text and Binary Payloads using WebSocket (TOTD #186)

  - by arungupta

  TOTD #185 explained how to process text and binary payloads in a WebSocket endpoint. In summary, a text payload may be received as public void receiveTextMessage(String message) {    . . . } And binary payload may be received as: public void recieveBinaryMessage(ByteBuffer message) {    . . .} As you realize, both of these methods receive the text and binary data in raw format. However you may like to receive and send the data using a POJO. This marshaling and unmarshaling can be done in the method implementation but JSR 356 API provides a cleaner way. For encoding and decoding text payload into POJO, Decoder.Text (for inbound payload) and Encoder.Text (for outbound payload) interfaces need to be implemented. A sample implementation below shows how text payload consisting of JSON structures can be encoded and decoded. public class MyMessage implements Decoder.Text<MyMessage>, Encoder.Text<MyMessage> {     private JsonObject jsonObject;    @Override    public MyMessage decode(String string) throws DecodeException {        this.jsonObject = new JsonReader(new StringReader(string)).readObject();               return this;    }     @Override    public boolean willDecode(String string) {        return true;    }     @Override    public String encode(MyMessage myMessage) throws EncodeException {        return myMessage.jsonObject.toString();    } public JsonObject getObject() { return jsonObject; }} In this implementation, the decode method decodes incoming text payload to MyMessage, the encode method encodes MyMessage for the outgoing text payload, and the willDecode method returns true or false if the message can be decoded. The encoder and decoder implementation classes need to be specified in the WebSocket endpoint as: @WebSocketEndpoint(value="/endpoint", encoders={MyMessage.class}, decoders={MyMessage.class}) public class MyEndpoint { public MyMessage receiveMessage(MyMessage message) { . . . } } Notice the updated method signature where the application is working with MyMessage instead of the raw string. Note that the encoder and decoder implementations just illustrate the point and provide no validation or exception handling. Similarly Encooder.Binary and Decoder.Binary interfaces need to be implemented for encoding and decoding binary payload. Here are some references for you: JSR 356: Java API for WebSocket - Specification (Early Draft) and Implementation (already integrated in GlassFish 4 promoted builds) TOTD #183 - Getting Started with WebSocket in GlassFish TOTD #184 - Logging WebSocket Frames using Chrome Developer Tools, Net-internals and Wireshark TOTD #185: Processing Text and Binary (Blob, ArrayBuffer, ArrayBufferView) Payload in WebSocket Subsequent blogs will discuss the following topics (not necessary in that order) ... Error handling Interface-driven WebSocket endpoint Java client API Client and Server configuration Security Subprotocols Extensions Other topics from the API

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• Integrating Amazon S3 in Java via NetBeans IDE

  - by Geertjan

  To continue from yesterday, let's set up a scenario that enables us to make use of this drag/drop service in NetBeans IDE: The above service is applicable to Amazon S3, an Amazon storage provider that is typically used to store large binary files. In Amazon S3, every object stored is contained in a bucket. Buckets partition the namespace of objects stored in Amazon S3. More on buckets here. Let's use the tools in NetBeans IDE to create a Java application that accesses our Amazon S3 buckets. Create a Java application named "AmazonBuckets" with a main class named "AmazonBuckets". Open the main class and then drag the above service into the main method of the class. Now, NetBeans IDE will create all the other classes and the properties file that you see in the screenshot below. The first thing to do is to open the properties file above and enter the access key and secret: access_key=SOMETHINGsecret=SOMETHINGELSE Now you're all set up. Make sure to, of course, actually have some buckets available: Then rewrite the Java class to parse the XML that is returned via the generated code: package amazonbuckets;import java.io.ByteArrayInputStream;import java.io.IOException;import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.parsers.ParserConfigurationException;import org.netbeans.saas.amazon.AmazonS3Service;import org.netbeans.saas.RestResponse;import org.w3c.dom.DOMException;import org.w3c.dom.Document;import org.w3c.dom.Node;import org.w3c.dom.NodeList;import org.xml.sax.InputSource;import org.xml.sax.SAXException;public class AmazonBuckets {    public static void main(String[] args) {        try {            RestResponse result = AmazonS3Service.getBuckets();            String dataAsString = result.getDataAsString();            DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();            DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();            Document doc = dBuilder.parse(                    new InputSource(new ByteArrayInputStream(dataAsString.getBytes("utf-8"))));            NodeList bucketList = doc.getElementsByTagName("Bucket");            for (int i = 0; i < bucketList.getLength(); i++) {                Node node = bucketList.item(i);                System.out.println("Bucket Name: " + node.getFirstChild().getTextContent());            }        } catch (IOException | ParserConfigurationException | SAXException | DOMException ex) {        }    }}That's all. This is simpler to setup than the scenario described yesterday. Also notice that there are other Amazon S3 services you can interact with from your Java code, again after generating a heap of code after drag/drop into a Java source file: I tried the above, e.g., I created a new Amazon S3 bucket after dragging "createBucket", adding my credentials in the properties file, and then running the code that had been created. I.e., without adding a single line of code I was able to programmatically create new buckets. The above outlines a handy set of tools and techniques to use if you want to let your users store and access data in Amazon S3 buckets directly from the application you've created for them.

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• Is my class structure good enough?

  - by Rivten

  So I wanted to try out this challenge on reddit which is mostly about how you structure your data the best you can. I decided to challenge my C++ skills. Here's how I planned this. First, there's the Game class. It deals with time and is the only class main has access to. A game has a Forest. For now, this class does not have a lot of things, only a size and a Factory. Will be put in better use when it will come to SDL-stuff I guess A Factory is the thing that deals with the Game Objects (a.k.a. Trees, Lumberjack and Bears). It has a vector of all GameObjects and a queue of Events which will be managed at the end of one month. A GameObject is an abstract class which can be updated and which can notify the Event Listener The EventListener is a class which handles all the Events of a simulation. It can recieve events from a Game Object and notify the Factory if needed, the latter will manage correctly the event. So, the Tree, Lumberjack and Bear classes all inherits from GameObject. And Sapling and Elder Tree inherits from Tree. Finally, an Event is defined by an event_type enumeration (LUMBERJACK_MAWED, SAPPLING_EVOLUTION, ...) and an event_protagonists union (a GameObject or a pair of GameObject (who killed who ?)). I was quite happy at first with this because it seems quite logic and flexible. But I ended up questionning this structure. Here's why : I dislike the fact that a GameObject need to know about the Factory. Indeed, when a Bear moves somewhere, it needs to know if there's a Lumberjack ! Or it is the Factory which handles places and objects. It would be great if a GameObject could only interact with the EventListener... or maybe it's not that much of a big deal. Wouldn't it be better if I separate the Factory in three vectors ? One for each kind of GameObject. The idea would be to optimize research. If I'm looking do delete a dead lumberjack, I would only have to look in one shorter vector rather than a very long vector. Another problem arises when I want to know if there is any particular object in a given case because I have to look for all the gameObjects and see if they are at the given case. I would tend to think that the other idea would be to use a matrix but then the issue would be that I would have empty cases (and therefore unused space). I don't really know if Sapling and Elder Tree should inherit from Tree. Indeed, a Sapling is a Tree but what about its evolution ? Should I just delete the sapling and say to the factory to create a new Tree at the exact same place ? It doesn't seem natural to me to do so. How could I improve this ? Is the design of an Event quite good ? I've never used unions before in C++ but I didn't have any other ideas about what to use. Well, I hope I have been clear enough. Thank you for taking the time to help me !

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• Identity in .NET 4.5&ndash;Part 3: (Breaking) changes

  - by Your DisplayName here!

  I recently started porting a private build of Thinktecture.IdentityModel to .NET 4.5 and noticed a number of changes. The good news is that I can delete large parts of my library because many features are now in the box. Along the way I found some other nice additions. ClaimsIdentity now has methods to query the claims collection, e.g. HasClaim(), FindFirst(), FindAll(). ClaimsPrincipal has those methods as well. But they work across all contained identities. Nice! ClaimsPrincipal.Current retrieves the ClaimsPrincipal from Thread.CurrentPrincipal. Combined with the above changes, no casting necessary anymore. SecurityTokenHandler now has read and write methods that work directly with strings. This makes it much easier to deal with non-XML tokens like SWT or JWT. A new session security token handler that uses the ASP.NET machine key to protect the cookie. This makes it easier to get started in web farm scenarios. No need for a custom service host factory or the federation behavior anymore. WCF can be switched into “WIF mode” with the useIdentityConfiguration switch (odd name though). Tooling has become better and the new test STS makes it very easy to get started. On the other hand – and that was kind of expected – to bring claims into the core framework, there are also some breaking changes for WIF code. If you want to migrate (and I would recommend that), most changes to your code are mechanical. The following is a brain dump of the changes I encountered. Assembly Microsoft.IdentityModel is gone. The new functionality is now in mscorlib, System.IdentityModel(.Services) and System.ServiceModel. All the namespaces have changed as well. No IClaimsPrincipal and IClaimsIdentity anymore. Configuration section has been split into <system.identityModel /> and <system.identityModel.services />. WCF configuration story has changed as well. Claim.ClaimType is now Claim.Type. ClaimCollection is now IEnumerable<Claim>. IsSessionMode is now IsReferenceMode. Bootstrap token handling is different now. ClaimsPrincipalHttpModule is gone. This is not really needed anymore, apart from maybe claims transformation (see here). Various factory methods on ClaimsPrincipal are gone (e.g. ClaimsPrincipal.CreateFromIdentity()). SecurityTokenHandler.ValidateToken now returns a ReadOnlyCollection<ClaimsIdentity>. Some lower level helper classes are gone or internal now (e.g. KeyGenerator). The WCF WS-Trust bindings are gone. I think this is a pity. They were *really* useful when doing work with WSTrustChannelFactory. Since WIF is part of the Windows operating system and also supported in future versions of .NET, there is no urgent need to migrate to the 4.5 claims model. But obviously, going forward, at some point you want to make the move.

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• Multiple Zend application code organisation

  - by user966936

  For the past year I have been working on a series of applications all based on the Zend framework and centered on a complex business logic that all applications must have access to even if they don't use all (easier than having multiple library folders for each application as they are all linked together with a common center). Without going into much detail about what the project is specifically about, I am looking for some input (as I am working on the project alone) on how I have "grouped" my code. I have tried to split it all up in such a way that it removes dependencies as much as possible. I'm trying to keep it as decoupled as I logically can, so in 12 months time when my time is up anyone else coming in can have no problem extending on what I have produced. Example structure: applicationStorage\ (contains all applications and associated data) applicationStorage\Applications\ (contains the applications themselves) applicationStorage\Applications\external\ (application grouping folder) (contains all external customer access applications) applicationStorage\Applications\external\site\ (main external customer access application) applicationStorage\Applications\external\site\Modules\ applicationStorage\Applications\external\site\Config\ applicationStorage\Applications\external\site\Layouts\ applicationStorage\Applications\external\site\ZendExtended\ (contains extended Zend classes specific to this application example: ZendExtended_Controller_Action extends zend_controller_Action ) applicationStorage\Applications\external\mobile\ (mobile external customer access application different workflow limited capabilities compared to full site version) applicationStorage\Applications\internal\ (application grouping folder) (contains all internal company applications) applicationStorage\Applications\internal\site\ (main internal application) applicationStorage\Applications\internal\mobile\ (mobile access has different flow and limited abilities compared to main site version) applicationStorage\Tests\ (contains PHP unit tests) applicationStorage\Library\ applicationStorage\Library\Service\ (contains all business logic, services and servicelocator; these are completely decoupled from Zend framework and rely on models' interfaces) applicationStorage\Library\Zend\ (Zend framework) applicationStorage\Library\Models\ (doesn't know services but is linked to Zend framework for DB operations; contains model interfaces and model datamappers for all business objects; examples include Iorder/IorderMapper, Iworksheet/IWorksheetMapper, Icustomer/IcustomerMapper) (Note: the Modules, Config, Layouts and ZendExtended folders are duplicated in each application folder; but i have omitted them as they are not required for my purposes.) For the library this contains all "universal" code. The Zend framework is at the heart of all applications, but I wanted my business logic to be Zend-framework-independent. All model and mapper interfaces have no public references to Zend_Db but actually wrap around it in private. So my hope is that in the future I will be able to rewrite the mappers and dbtables (containing a Models_DbTable_Abstract that extends Zend_Db_Table_Abstract) in order to decouple my business logic from the Zend framework if I want to move my business logic (services) to a non-Zend framework environment (maybe some other PHP framework). Using a serviceLocator and registering the required services within the bootstrap of each application, I can use different versions of the same service depending on the request and which application is being accessed. Example: all external applications will have a service_auth_External implementing service_auth_Interface registered. Same with internal aplications with Service_Auth_Internal implementing service_auth_Interface Service_Locator::getService('Auth'). I'm concerned I may be missing some possible problems with this. One I'm half-thinking about is a config.ini file for all externals, then a separate application config.ini overriding or adding to the global external config.ini. If anyone has any suggestions I would be greatly appreciative. I have used contextswitching for AJAX functions within the individual applications, but there is a big chance both external and internal will get web services created for them. Again, these will be separated due to authorization and different available services. \applicationstorage\Applications\internal\webservice \applicationstorage\Applications\external\webservice

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