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• How to create a magic square in PHP?

  - by TerranRich

  I'd like to try my hand at creating a Magic Square in PHP (i.e. a grid of numbers that all add up to the same value), but I really don't know where to start. I know of the many methods that create magic square, such as starting "1" at a fixed position, then moving in a specific direction with each iteration. But that doesn't create a truly randomized Magic Square, which is what I'm aiming for. I want to be able to generate an N-by-N Magic Square of N² numbers where each row and column adds up to N(N²+1)/2 (e.g. a 5x5 square where all rows/columns add up to 65 — the diagonals don't matter). Can anybody provide a starting point? I don't want anybody to do the work for me, I just need to know how to start such a project? I know of one generator, written in Java (http://www.dr-mikes-math-games-for-kids.com/how-to-make-a-magic-square.html) but the last Java experience I had was over 10 years ago before I quickly abandoned it. Therefore, I don't really understand what the code is actually doing. I did notice, however, that when you generate a new square, it shows the numbers 1-25 (for a 5x5 square), in order, before quickly generating a fresh randomized square.

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• NHibernate.MappingException - Troubles Shooting Checklist (no persister for)

  - by Berryl

  Here's a starter list: 1) if hbm is hand generated, is it an embedded resource? 2) if using FNH, does it pass a PerssistenceSpecification test? 3) if not using FNH, can you save and then load the persisted class? 4) more? I'm sure many of you have gotten this one at one point or another. But have you ever gotten it when you knew your mapping was set up correctly? I started getting this exception after I started using a new repository design, but only in one scenario! PersistenceSpecification tests pass, as do all repository methods (using SQLite). The scenario that leads to the exception is when legacy projects from a different db are converted to green field system. The legacy system is from a different database and has it's own session factory, which should be irrelevant because the error comes after previously unconverted Projects are retrieved and in memory. As the routine tries to save these unconverted Projects into the new database, the exception is thrown, full stack trace below. Any ideas on how to build up the trouble shooting check list and solves this problem? Cheers, Berryl === the Exception trace ===== failed: NHibernate.MappingException : No persister for: Smack.ConstructionAdmin.Domain.Model.Projects.Project at NHibernate.Impl.SessionFactoryImpl.GetEntityPersister(String entityName) at NHibernate.Impl.SessionImpl.GetEntityPersister(String entityName, Object obj) at NHibernate.Engine.ForeignKeys.IsTransient(String entityName, Object entity, Nullable`1 assumed, ISessionImplementor session) at NHibernate.Event.Default.AbstractSaveEventListener.GetEntityState(Object entity, String entityName, EntityEntry entry, ISessionImplementor source) at NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.PerformSaveOrUpdate(SaveOrUpdateEvent event) at NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.OnSaveOrUpdate(SaveOrUpdateEvent event) at NHibernate.Impl.SessionImpl.FireSaveOrUpdate(SaveOrUpdateEvent event) at NHibernate.Impl.SessionImpl.SaveOrUpdate(Object obj) NHibernate\Repository\FabioNHibRepository.cs(46,0): at Smack.Core.Data.NHibernate.Repository.FabioNHibRepository`1.Add(T item) LegacyConversion\LegacyBatchUpdater.cs(20,0): at Smack.ConstructionAdmin.Data.LegacyConversion.LegacyBatchUpdater.ConvertOpenLegacyProjects(ILegacyProjectDao legacyProjectDao, IProjectRepository greenProjectRepository) Data\Brownfield\ProjectBatchUpdate_SQLiteTests.cs(19,0): at Smack.ConstructionAdmin.Tests.Data.Brownfield.ProjectBatchUpdate_SQLiteTests.Test()

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• In iTextSharp, can we set the vertical position of the pdfwriter?

  - by Pandincus

  Hello, I've recently started using iTextSharp to generate PDF reports from data. It works quite nicely. In one particular report, I need a section to always appear at the bottom of the page. I'm using the PdfContentByte to create a dashed line 200f from the bottom: cb.MoveTo(0f, 200f); cb.SetLineDash(8, 4, 0); cb.LineTo(doc.PageSize.Width, 200f); cb.Stroke(); Now I'd like to insert content below that line. However, (as expected) the PdfContentByte methods don't change the vertical position of the PdfWriter. New paragraphs, for example, appear earlier in the page. // appears wherever my last content was, NOT below the dashed line doc.Add(new Paragraph("test", _myFont)); Is there some way to instruct the pdfwriter that I'd like to advance the vertical position to below the dashed line now, and continue inserting content there? There is a GetVerticalPosition() method -- it'd be nice if there was a corresponding Setter :-). // Gives me the vertical position, but I can't change it var pos = writer.GetVerticalPosition(false); So, is there any way to set the writer's position by hand? Thanks!

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• Need Advice on designing ATL inproc Server (dll) that serves as both a soure and a sink of events.

  - by Andrew

  Hi, I need to design an ATL inproc server that besides exposing methods and properties, also can fire events (source) and serve as a sink for a third party COM control that fires events. I would assume that this is a fairly common requirement. I can also foresee several "gotchas" that I would like to read up on before commencing the design. My questions/concerns are: Can someone point me to an example? Which threading model to use? Should I have a seperate COM object for the sink? Should I, and how do I, protect certain memory. For example, my server will receive data from the third party control. It will save this, and in some cases, fire an event to interested clients. The interested clients will request the data through a standard method or property. I did try to research this myself. I can find many examples of COM servers that are soures, and some that are sinks, but never both. The only post I did find was this: http://www.generation-nt.com/us/atl-control-an-event-source-sink-help-9098542.html Which strongly advocates putting the sink on a seperate COM object. Any leads, tutorials or ideas would be much appreciated. Thanks, Andrew

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• Help understanding the Single Responsibility Principle

  - by user204588

  I'm trying to understand what a responsibility actually is so I want to use an example of something I'm currently working on. I have a app that imports product information from one system to another system. The user of the apps gets to choose various settings for which product fields in one system that want to use in the other system. So I have a class, say ProductImporter and it's responsibility is to import products. This class is large, probably too large. The methods in this class are complex and would be for example, getDescription. This method doesn't simply grab a description from the other system but sets a product description based on various settings set by the user. If I were to add a setting and a new way to get a description, this class could change. So, is that two responsibilities? Is there one that imports products and one that gets a description. It would seem this way, almost every method I have would be in it's own class and that seems like overkill. I really need a good description of this principle because it's hard for me to completely understand. I don't want needless complexity.

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• List of objects or parallel arrays of properties?

  - by Headcrab

  The question is, basically: what would be more preferable, both performance-wise and design-wise - to have a list of objects of a Python class or to have several lists of numerical properties? I am writing some sort of a scientific simulation which involves a rather large system of interacting particles. For simplicity, let's say we have a set of balls bouncing inside a box so each ball has a number of numerical properties, like x-y-z-coordinates, diameter, mass, velocity vector and so on. How to store the system better? Two major options I can think of are: to make a class "Ball" with those properties and some methods, then store a list of objects of the class, e. g. [b1, b2, b3, ...bn, ...], where for each bn we can access bn.x, bn.y, bn.mass and so on; to make an array of numbers for each property, then for each i-th "ball" we can access it's 'x' coordinate as xs[i], 'y' coordinate as ys[i], 'mass' as masses[i] and so on; To me it seems that the first option represents a better design. The second option looks somewhat uglier, but might be better in terms of performance, and it could be easier to use it with numpy and scipy, which I try to use as much as I can. I am still not sure if Python will be fast enough, so it may be necessary to rewrite it in C++ or something, after initial prototyping in Python. Would the choice of data representation be different for C/C++? What about a hybrid approach, e.g. Python with C++ extension?

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• Calling MethodBase's Invoke on a constructor (reflection)

  - by Alix

  Hi everyone. First of all, sorry if this has been asked before. I've done a pretty comprehensive search and found nothing quite like it, but I may have missed something. And now to the question: I'm trying to invoke a constructor through reflection, with no luck. Basically, I have an object that I want to clone, so I look up the copy constructor for its type and then want to invoke it. Here's what I have: public Object clone(Object toClone) { MethodBase copyConstructor = type.GetConstructor( new Type[] { toClone.GetType() }); return method.Invoke(toClone, new object[] { toClone }); //<-- doesn't work } I call the above method like so: List list = new List(new int[] { 0, 1, 2 }); List clone = (List) clone(list); Now, notice the invoke method I'm using is MethodBase's invoke. ConstructorInfo provides an invoke method that does work if invoked like this: return ((ConstructorInfo) method).Invoke(new object[] { toClone }); However, I want to use MethodBase's method, because in reality instead of looking up the copy constructor every time I will store it in a dictionary, and the dictionary contains both methods and constructors, so it's a Dictionary<MethodBase>, not Dictionary<ConstructorInfo>. I could of course cast to ConstructorInfo as I do above, but I'd rather avoid the casting and use the MethodBase method directly. I just can't figure out the right parameters. Any help? Thanks so much.

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• what is wrong in java AES decrypt function?

  - by rohit

  hi, i modified the code available on http://java.sun.com/developer/technicalArticles/Security/AES/AES_v1.html and made encrypt and decrypt methods in program. but i am getting BadpaddingException.. also the function is returning null.. why it is happing?? whats going wrong? please help me.. these are variables i am using: kgen = KeyGenerator.getInstance("AES"); kgen.init(128); raw = new byte[]{(byte)0x00,(byte)0x11,(byte)0x22,(byte)0x33,(byte)0x44,(byte)0x55,(byte)0x66,(byte)0x77,(byte)0x88,(byte)0x99,(byte)0xaa,(byte)0xbb,(byte)0xcc,(byte)0xdd,(byte)0xee,(byte)0xff}; skeySpec = new SecretKeySpec(raw, "AES"); cipher = Cipher.getInstance("AES"); plainText=null; cipherText=null; following is decrypt function.. public String decrypt(String cipherText) { try { cipher.init(Cipher.DECRYPT_MODE, skeySpec); byte[] original = cipher.doFinal(cipherText.getBytes()); plainText = new String(original); } catch(BadPaddingException e) { } return plainText; }

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• autocommit and @Transactional and Cascading with spring, jpa and hibernate

  - by subes

  Hi, what I would like to accomplish is the following: have autocommit enabled so per default all queries get commited if there is a @Transactional on a method, it overrides the autocommit and encloses all queries into a single transaction, thus overriding the autocommit if there is a @Transactional method that calls other @Transactional annotated methods, the outer most annotation should override the inner annotaions and create a larger transaction, thus annotations also override eachother I am currently still learning about spring-orm and couldn't find documentation about this and don't have a test project for this yet. So my questions are: What is the default behaviour of transactions in spring? If the default differs from my requirement, is there a way to configure my desired behaviour? Or is there a totally different best practice for transactions? --EDIT-- I have the following test-setup: @javax.persistence.Entity public class Entity { @Id @GeneratedValue private Integer id; private String name; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } } @Repository public class Dao { @PersistenceContext private EntityManager em; public void insert(Entity ent) { em.persist(ent); } @SuppressWarnings("unchecked") public List<Entity> selectAll() { List<Entity> ents = em.createQuery("select e from " + Entity.class.getName() + " e").getResultList(); return ents; } } If I have it like this, even with autocommit enabled in hibernate, the insert method does nothing. I have to add @Transactional to the insert or the method calling insert for it to work... Is there a way to make @Transactional completely optional?

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• Rewrite arrays using collections

  - by owca

  I have a task, which I was able to do with the use of simplest methods - arrays. Now I'd like to go further and redo it using some more complicated java features like collections, but I've never used anything more complicated than 2d matrix. What should I look at and how to start with it. Should Tower become a Collection ? And here's the task : We have two classes - Tower and Block. Towers are built from Blocks. Ande here's sample code for testing: Block k1=new Block("yellow",1,5,4); Block k2=new Block("blue",2,2,6); Block k3=new Block("green",3,4,2); Block k4=new Block("yellow",1,5,4); Tower tower=new Tower(); tower.add(k1,k2,k3); "Added 3 blocks." System.out.println(tower); "block: green, base: 4cm x 3cm, thicknes: 2 cm block: blue, base: 6cm x 2cm, thicknes: 2 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm" tower.add(k2); "Tower already contains this block." tower.add(k4); "Added 1 block." System.out.println(tower); "block: green, base: 4cm x 3cm, thicknes: 2 cm block: blue, base: 6cm x 2cm, thicknes: 2 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm" tower.delete(k1); "Deleted 1 block" tower.delete(k1); "Block not in tower" System.out.println(tower); "block: blue, base: 6cm x 2cm, thicknes: 2 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm" Let's say I will treat Tower as a collection of blocks. How to perform search for specific block among whole collection ? Or should I use other interface ?

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• Best emailing approach with template emails

  - by Harun Baris Bulut

  Hi all, We are creating a project with lots of different mail templates in it. There are different messages for different purposes and we are trying to make the coding easy and understandable for the future. By the way we have different transport classes like e-mail, sms, twitter vs... Now we are doing this but I dont know if there is a better solution. We have a class called H2B_Message_Container_Mail_About_Blablabla it has 4 methods; interface H2B_Message_Mail_Interface { public function setName($name); public function setValue($key, $value); public function getMailBody(); public function getMailSubject(); } and in the mail body there are various variables as expected. before we send the mail, we get the variable values from the database with JSON format and decode it. Then we send it like; $mail = new H2B_Message_Mail(); $mail->setTemplate($newTemplate); $mail->send(); The question is; is there a better way to do this ?

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• Spring factory beans not always initialised before being used.

  - by aos

  Hi, I am using spring to initialise my beans. I have configured a bean which I intend to use as a factory bean. <bean id="jsServicesFactory" class="x.y.z.JSServicesFactory" /> It is a very basic class - which has 4 getter methods. One example is public final PortletRegistry getPortletRegistry() { PortletRegistry registry = (PortletRegistry) JetspeedPortletServices .getSingleton().getService("PortletRegistryComponent"); return registry; } I have a 2nd bean which uses this factory beans to set one of its properties <bean id="batchManagerService" class="x.y.z.BatchManagerService"> ... <property name="portletRegistry"> <bean factory-bean="jsServicesFactory" factory-method="getPortletRegistry" /> </property> ... When I start my server in RAD, this all works perfectly. However when I deploy to Linux I sometimes get the following error ERROR org.springframework.web.context.ContextLoader - Context initialization failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'batchManagerService' defined in ServletContext resource [/WEB-INF/context/root/batchManagerContext.xml]: Cannot create inner bean 'jsServicesFactory$created#70be70be' while setting bean property 'portletRegistry'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jsServicesFactory$created#70be70be' defined in ServletContext resource [/WEB-INF/context/root/batchManagerContext.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanDefinitionStoreException: Factory method [public final org.apache.jetspeed.components.portletregistry.PortletRegistry x.y.z.JSServicesFactory.getPortletRegistry()] threw exception; nested exception is java.lang.NullPointerException I have tried adding depends-on="jsServicesFactory" to my bean batchManagerService but it didn't work. Any ideas? Thanks

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• How do I copy or move an NSManagedObject from one context to another?

  - by Aeonaut

  I have what I assume is a fairly standard setup, with one scratchpad MOC which is never saved (containing a bunch of objects downloaded from the web) and another permanent MOC which persists objects. When the user selects an object from scratchMOC to add to her library, I want to either 1) remove the object from scratchMOC and insert into permanentMOC, or 2) copy the object into permanentMOC. The Core Data FAQ says I can copy an object like this: NSManagedObjectID *objectID = [managedObject objectID]; NSManagedObject *copy = [context2 objectWithID:objectID]; (In this case, context2 would be permanentMOC.) However, when I do this, the copied object is faulted; the data is initially unresolved. When it does get resolved, later, all of the values are nil; none of the data (attributes or relationships) from the original managedObject are actually copied or referenced. Therefore I can't see any difference between using this objectWithID: method and just inserting an entirely new object into permanentMOC using insertNewObjectForEntityForName:. I realize I can create a new object in permanentMOC and manually copy each key-value pair from the old object, but I'm not very happy with that solution. (I have a number of different managed objects for which I have this problem, so I don't want to have to write and update copy: methods for all of them as I continue developing.) Is there a better way?

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• What is wrong with my Basic Authentication in my Browser?

  - by Pure.Krome

  Hi folks, i'm trying to goto the following url :- http://user1:pass1@localhost:1234/api/users?format=xml nothing to complex. Notice how i've got the username/password in the url? this, i believe, is for basic authentication. When I do that, the Request Headers are MISSING the 'Authorize' header. Er... that's not right :( I have anonymous authentication only setup on the site. I don't want to have anon off and basic turned on .. because not all of the site requires basic.. only a few action methods. So .. why is this not working? Is this something to do with the fact my code is not sending a 401 challenge or some crap? For What It's Worth, my site is ASP.NET MVC1 running on IIS7 (and the same thing happens when i run it on cassini). Update: If this is an illegal way of calling a resource using basic auth (ala security flaw) .. then is this possible to do, for an ASP.NET MVC website .. per action method (and not the entire site, per say)?

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• Add new types to Go

  - by nevalu

  I'm trying add new types for that been managed/used as in Go core types. To create new types is anything very interesting to validate data before of send it to a non-SQL DBMS or to check data from a form. Go uses univeral constants to define them at global level: var DateType = universe.DefineType("date", universePos, &dateType{}) In this case they're defined to be called from a package like types: var Date = &dateType{} I get these errors: test.go:58: o.lit undefined (cannot refer to unexported field lit) test.go:62: *dateType is not Type missing Pos() token.Position The code is based on: http://github.com/tav/go/blob/master/src/pkg/exp/eval/value.go http://github.com/tav/go/blob/master/src/pkg/exp/eval/type.go package main import ( "exp/eval" "fmt" // "go/token" ) // http://github.com/tav/go/blob/master/src/pkg/exp/eval/value.go type DateValue interface { eval.Value Get(*eval.Thread) string Set(*eval.Thread, string) } /* Date */ type dateV string func (v *dateV) String() string { return fmt.Sprint(*v) } func (v *dateV) Assign(t *eval.Thread, o eval.Value) { *v = dateV(o.(DateValue).Get(t)) } func (v *dateV) Get(*eval.Thread) string { return string(*v) } func (v *dateV) Set(t *eval.Thread, x string) { *v = dateV(x) } // http://github.com/tav/go/blob/master/src/pkg/exp/eval/type.go type Type interface { eval.Type // isDate returns true if this is a date type. isDate() bool } /* Common type */ type commonType struct{} // added func (commonType) isDate() bool { return false } /* Date */ type dateType struct { commonType } // * It should not be an universal constant //var universePos = token.Position{"<universe>", 0, 0, 0} // added //var DateType = universe.DefineType("date", universePos, &dateType{}) var Date = &dateType{} func (t *dateType) compat(o Type, conv bool) bool { t2, ok := o.lit().(*dateType) return ok && t == t2 } func (t *dateType) lit() Type { return t } func (t *dateType) isDate() bool { return true } func (t *dateType) String() string { return "<date>" } func (t *dateType) Zero() eval.Value { res := dateV("") return &res } /* Named types */ /* type NamedType struct { eval.NamedType Def Type }*/ type NamedType struct { // added // token.Position Name string // Underlying type. If incomplete is true, this will be nil. // If incomplete is false and this is still nil, then this is // a placeholder type representing an error. Def Type // True while this type is being defined. incomplete bool methods map[string]eval.Method } func (t *NamedType) isDate() bool { return t.Def.isDate() } /* *********************** */ func main() { print("foo") }

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• Abort SAX parsing mid-document?

  - by CSharperWithJava

  I'm parsing a very simple XML schema with a SAX parser in Android. An example file would be <Lists> <List name="foo"> <Note title="note 1" .../> <Note title="note 2" .../> </List> <List name="bar"> <Note title="note 3" .../> </List> </Lists> The ... represents more note data as attributes that aren't important to question. I use a SAX parser to parse the document and only implement the startElement and 'endElement' methods of the HandlerBase to handle Note and List nodes. However, In some cases the files can be very large and take some time to process. I'd like to be able to abort the parsing process at any time (i.e. user presses cancel button). The best way I've come up with is to throw an exception from my startElement method when certain conditions are met (i.e. boolean stopParsing is true). Is there a better way to do this? I've always used DOM style parsers, so I don't fully understand the SAX parser. One final note, I'm running this on Android, so I will have the Parser running on a worker thread to keep the UI responsive. If you know how I can kill the thread safely while the parser is running that would answer my question as well.

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• MongoDB architectural question

  - by pex

  I have to store 4 Models. Let's say a Post that has many and belongs to many Categories. Category on the other hand has many Qualities. At the moment I'm of the opinion, that Post and Categories are Documents. Qualities becomes an EmbeddedDocument of Categories. We're coming to the root problem: There are a lot of Votes on Qualities that belong to a Post. I thought about embed Votes in Post and give it a quality_id. I am really expecting a lot of Votes and there has to be a possibility to filter them (e.g by Username / Usergroup / Date voted). I worked with MongoMapper and I think the missing existence of find methods for EmbeddedDocuments could become a killer. On the other hand I'm wondering about performance issues. What if I want to provide a Post without all the Votes, but only a few. Or, what if I define an own Document for Votes and have tons of Vote-Documents? Wouldn't that become a performance killer?

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• Unity to dispose of object

  - by Johan Levin

  Is there a way to make Unit dispose property-injected objects as part of the Teardown? The background is that I am working on an application that uses ASP.NET MVC 2, Unity and WCF. We have written our own MVC controller factory that uses unity to instantiate the controller and WCF proxies are injected using the [Dependency] attribute on public properties of the controller. At the end of the page life cycle the ReleaseController method of the controller factory is called and we call IUnityContainer.Teardown(theMvcController). At that point the controller is disposed as expected but I also need to dispose the injected wcf-proxies. (Actually I need to call Close and/or Abort on them and not Dispose but that is a later problem.) I could of course override the controllers' Dispose methods and clean up the proxies there, but I don't want the controllers to have to know about the lifecycles of the injected interfaces or even that they refer to WCF proxies. If I need to write code myself for this - what would be the best extension point? I'd appreciate any pointer.

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• How does a java web project architecture look like without EJB3 ?

  - by Hendrik

  A friend and I are building a fairly complex website based on java. (PHP would have been more obvious but we chose for java because the educational aspect of this project is important to us) We have already decided to use JSF (with richfaces) for the front end and JPA for the backend and so far we have decided not to use EJB3 for the business layer. The reason we've decided not to use EJB3 is because - and please correct me if I am wrong - if we use EJB3 we can only run it on a full blown java application server like jboss and if we don't use EJB3 we can still run it on a lightweight server like tomcat. We want to keep speed and cost of our future web server in mind. So far i've worked on two JEE projects and both used the full stack with web business logic factories/persistence service entities with every layer a seperate module. Now here is my question, if you dont use EJB3 in the business logic layer. What does the layer look like? Please tell what is common practice when developing java web projects without ejb3? Do you think business logic layer can be thrown out altogether and have business logic in the backing beans? If you keep the layer, do you have all business methods static? Or do you initialize each business class as needed in the backing beans in every session as needed?

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• How to mimic built-in .NET serialization idioms?

  - by Matt Enright

  I have a library (written in C#) for which I need to read/write representations of my objects to disk (or to any Stream) in a particular binary format (to ensure compatibility with C/Java library implementations). The format requires a fair amount of bit-packing and some DEFLATE'd bytestreams. I would like my library, however, to be as idiomatic .NET as possible, however, and so would like to provide an API as close as possible to the normal binary serialization process. I'm aware of the ability to implement the IFormatter interface, but being that I really am unable to reuse any part of the built-in serialization stack, is it worth doing this, or will it just bring unnecessary overhead. In other words: Implement IFormatter and co. OR Just provide "Serialize"/"Deserialize" methods that act on a Stream? A good point brought up below about needing the serialization semantics for any case involving Remoting. In a case where using MarshalByRef objects is feasible, I'm pretty sure that this won't be an issue, so leaving that aside are there any benefits or drawbacks to using the ISerializable/IFormatter versus a custom stack (or, is my understanding remoting incorrectly)?

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• Query eror handling in CodeIgniter

  - by Sajith S Narayanan

  Hi All, I am trying to execute an MySql query using the CI Active methods. If the query is malformed, then CI invokes internal server error 500 and quits without processing the next steps.. I need to roll back all the other queries processed before that error statement, and the roll back is also not happening.. can you help pls. The code snippets is as below: function dbInsertInformationToDB($data_array) { $returnID = ""; $uniqueDataArray = array(); // I prepare a array of values here $uniqueTableList = filter_unique_tables($data_array[2]); $this->db->trans_begin(); // inserting is done here // when there is a query error in $this->db->insert().. it is not rolling back the previous query executed foreach($uniqueTableList as $table_name) { $uniqueDataArray = filterDataArray($data_array,$table_name,2); $this->db->insert($table_name,$uniqueDataArray); if ($this->db->_error_message()) { $error = "I am caught!!"; } $returnID = $this->db->affected_rows(); } if ($this->db->trans_status() === FALSE) { $this->db->trans_rollback(); } else { $this->db->trans_commit(); } return "ERROR"; }

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• How can I place validating constraints on my method input parameters?

  - by rcampbell

  Here is the typical way of accomplishing this goal: public void myContractualMethod(final String x, final Set<String> y) { if ((x == null) || (x.isEmpty())) { throw new IllegalArgumentException("x cannot be null or empty"); } if (y == null) { throw new IllegalArgumentException("y cannot be null"); } // Now I can actually start writing purposeful // code to accomplish the goal of this method I think this solution is ugly. Your methods quickly fill up with boilerplate code checking the valid input parameters contract, obscuring the heart of the method. Here's what I'd like to have: public void myContractualMethod(@NotNull @NotEmpty final String x, @NotNull final Set<String> y) { // Now I have a clean method body that isn't obscured by // contract checking If those annotations look like JSR 303/Bean Validation Spec, it's because I borrowed them. Unfortunitely they don't seem to work this way; they are intended for annotating instance variables, then running the object through a validator. Which of the many Java design-by-contract frameworks provide the closest functionality to my "like to have" example? The exceptions that get thrown should be runtime exceptions (like IllegalArgumentExceptions) so encapsulation isn't broken.

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• Problem using NSXMLParser with NOAA data on iPhone

  - by Amagrammer

  Can anyone help me see why NSXMLParser is not causing these methods parser:didStartElement:namespaceURI:qualifiedName:attributes: parser:didEndElement:namespaceURI:qualifiedName:attributes: to fire for the part of the following data: <?xml version="1.0" encoding="ISO-8859-1"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"><SOAP-ENV:Body><ns1:NDFDgenResponse xmlns:ns1=""><dwmlOut xsi:type="xsd:string"><?xml version="1.0"?> <dwml version="1.0" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://www.nws.noaa.gov/forecasts/xml/DWMLgen/schema/DWML.xsd"> (body excluded) </dwml> </dwmlOut></ns1:NDFDgenResponse></SOAP-ENV:Body></SOAP-ENV:Envelope> I'm not an XML expert, but to me, the part looks like just a regular element, to be parsed just like the parts before it. I do get two parser:parseErrorOccurred: errors, #200 and #201, but they occur during the parsing of the <SOAP-ENV:Body> element, not the element, so I'm not sure if they are relevant. Thanks for any help you can give me.

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• QT: custom widget in QScrollArea

  - by slimscsi

  I am attempting to create a custom widget. My Widget renders itself unless it is inside a scroll area. The code below works. If I change the if(0) to an if(1) inside the MainWindow constructor, it will not render the "Hello World" string. I assume that I must (re)implement some additional methods, but so far I have not been able to find the correct ones with trial and error. // hellowidget.h #ifndef HELLOWIDGET_H #define HELLOWIDGET_H #include <QtGui> class HelloWidget : public QWidget { Q_OBJECT public: HelloWidget(QWidget *parent = 0); void paintEvent(QPaintEvent *event); }; #endif // HELLOWIDGET_H // hellowidget.cpp #include "hellowidget.h" HelloWidget::HelloWidget(QWidget *parent) : QWidget(parent) { } void HelloWidget::paintEvent(QPaintEvent *event) { QPainter painter(this); painter.drawText(rect(), Qt::AlignCenter, "Hello World"); } // mainwindow.h #ifndef MAINWINDOW_H #define MAINWINDOW_H #include <QtGui> class MainWindow : public QMainWindow { Q_OBJECT public: MainWindow(QWidget *parent = 0); ~MainWindow(); private: }; #endif // MAINWINDOW_H // mainwindow.cpp #include "mainwindow.h" #include "hellowidget.h" MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) { HelloWidget *hello = new HelloWidget; QWidget *central = hello; if( 0 ) { QScrollArea *scroll = new QScrollArea ; scroll->setWidget(hello); central = scroll; } setCentralWidget( central ); } MainWindow::~MainWindow() { } // main.cpp #include <QtGui/QApplication> #include "mainwindow.h" int main(int argc, char *argv[]) { QApplication a(argc, argv); MainWindow w; w.show(); return a.exec(); }

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• CPU friendly infinite loop

  - by Adi

  Writing an infinite loop is simple: while(true){ //add whatever break condition here } But this will trash the CPU performance. This execution thread will take as much as possible from CPU's power. What is the best way to lower the impact on CPU? Adding some Thread.Sleep(n) should do the trick, but setting a high timeout value for Sleep() method may indicate an unresponsive application to the operating system. Let's say I need to perform a task each minute or so in a console app. I need to keep Main() running in an "infinite loop" while a timer will fire the event that will do the job. I would like to keep Main() with the lowest impact on CPU. What methods do you suggest. Sleep() can be ok, but as I already mentioned, this might indicate an unresponsive thread to the operating system. LATER EDIT: I want to explain better what I am looking for: I need a console app not Windows service. Console apps can simulate the Windows services on Windows Mobile 6.x systems with Compact Framework. I need a way to keep the app alive as long as the Windows Mobile device is running. We all know that the console app runs as long as its static Main() function runs, so I need a way to prevent Main() function exit. In special situations (like: updating the app), I need to request the app to stop, so I need to infinitely loop and test for some exit condition. For example, this is why Console.ReadLine() is no use for me. There is no exit condition check. Regarding the above, I still want Main() function as resource friendly as possible. Let asside the fingerprint of the function that checks for the exit condition.

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