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  • Does the Java Memory Model (JSR-133) imply that entering a monitor flushes the CPU data cache(s)?

    - by Durandal
    There is something that bugs me with the Java memory model (if i even understand everything correctly). If there are two threads A and B, there are no guarantees that B will ever see a value written by A, unless both A and B synchronize on the same monitor. For any system architecture that guarantees cache coherency between threads, there is no problem. But if the architecture does not support cache coherency in hardware, this essentially means that whenever a thread enters a monitor, all memory changes made before must be commited to main memory, and the cache must be invalidated. And it needs to be the entire data cache, not just a few lines, since the monitor has no information which variables in memory it guards. But that would surely impact performance of any application that needs to synchronize frequently (especially things like job queues with short running jobs). So can Java work reasonably well on architectures without hardware cache-coherency? If not, why doesn't the memory model make stronger guarantees about visibility? Wouldn't it be more efficient if the language would require information what is guarded by a monitor? As i see it the memory model gives us the worst of both worlds, the absolute need to synchronize, even if cache coherency is guaranteed in hardware, and on the other hand bad performance on incoherent architectures (full cache flushes). So shouldn't it be more strict (require information what is guarded by a monitor) or more lose and restrict potential platforms to cache-coherent architectures? As it is now, it doesn't make too much sense to me. Can somebody clear up why this specific memory model was choosen? EDIT: My use of strict and lose was a bad choice in retrospect. I used "strict" for the case where less guarantees are made and "lose" for the opposite. To avoid confusion, its probably better to speak in terms of stronger or weaker guarantees.

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  • MVVM: where is the best place to integrate an id counter, in ViewModel or Repository or... ?

    - by msfanboy
    Hello, I am using http://loungerepo.codeplex.com/ this library needs a unique id when I persist my entities to the repository. I decided for integer not Guid. The question is now where do I retrieve a new integer and how do I do it? This is my current approach in the SchoolclassAdministrationViewModel.cs: public SchoolclassAdministrationViewModel() { _schoolclassRepo = new SchoolclassRepository(); _pupilRepo = new PupilRepository(); _subjectRepo = new SubjectRepository(); _currentSchoolclass = new SchoolclassModel(); _currentPupil = new PupilModel(); _currentSubject = new SubjectModel(); ... } private void AddSchoolclass() { // get the last free id for a schoolclass entity _currentSchoolclass.SchoolclassID = _schoolclassRepo.LastID; // add the new schoolclass entity to the repository _schoolclassRepo.Add(SchoolclassModel.SchoolclassModelToSchoolclass(_currentSchoolclass)); // add the new schoolclass entity to the ObservableCollection bound to the View Schoolclasses.Add(_currentSchoolclass); // Create a new schoolclass entity and the bound UI controls content gets cleaned CurrentSchoolclass = new SchoolclassModel(); } public class SchoolclassRepository : IRepository<Schoolclass> { private int _lastID; public SchoolclassRepository() { _lastID = FetchLastId(); } public void Add(Schoolclass entity) { //repo.Store(entity); } private int FetchLastId() { return // repo.GetIDOfLastEntryAndDoInc++ } public int LastID { get { return _lastID; } } } Explanation: Every time the user switches to the SchoolclassAdministrationViewModel which is datatemplated with a UserControl the saVM Ctor is called and the schoolclass repository is created wherein the FetchLastId() is called and I am up to date with the last ID doing a inc++ on it to get the free one... Do you have any better ideas? What I do not like about my current apporach: -Having a private method in repositry class because a repositry is to fetch data only not "entity logic" like the counter - Having to access from the ViewModel a public property - located in the repository -, actually its not the ViewModel concern to get a entity id and assign it. Actually the ViewModel should ask for a schoolclass POCO and get a SchoolclassModel to bind to the UI. But then I have again to re-read the Schoolclass properties into the SchoolclassModel properties what I want to avoid.

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  • Multiple "ObjectChangeTracker" getting created, can it be avoided?

    - by user555937
    Hi, We are working on a POC where we have following architecture (MVVM), WPF(Client) + WCF + Model(DataAccess)+ ADO.Net Entity Framework 4.0 (with SQL Server 2008 R2 as DB) All are different projects. In the DataAccess layer we have created different Entity Models(edmx) based on the functionality. The tables under perticular flow are grouped and created different entity models. We are using self tracking entities to and fro to communicate with the WPF client through wcf service. For Single model everything works fine. But when we created a Multiple models then few issues started coming. Mutliple models have few duplicate tables/entities. Two probels are, 1) When we try to access entities from different models mutiple objects "ObjectChangeTracker" are getting created. E.g. CompanyModel(edmx) - Company(Entity) - ObjectChangeTracker, ObjectState ProductModel(edmx) - Customer(Entity) - ObjectChangeTracker1, ObjectState1 OrderModel(edmx) - Oder(Entity) - ObjectChangeTracker2, ObjectState2 Is there any way to avoid this? 2) There are few tables which shared across the Models, E.g. Company(Entity) is used in All above mdoels. During compile time it does not thow any error. But run time It gives error saying "Schema specified is not valid. Errors: The mapping of CLR type to EDM type is ambiguous because multiple CLR types match the EDM type "Company"".. To resolve this, we renamed the entities with some prefix to make them Unique. Is there any other way we can resolve this without changing the name of the entity in the same assembly? Thanks in advance and appreciate if anyone has approach for these issues. Thanks, Kiran

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  • OSI Model

    - by kaleidoscope
    The Open System Interconnection Reference Model (OSI Reference Model or OSI Model) is an abstract description for layered communications and computer network protocol design. In its most basic form, it divides network architecture into seven layers which, from top to bottom, are the Application, Presentation, Session, Transport, Network, Data Link, and Physical Layers. It is therefore often referred to as the OSI Seven Layer Model. A layer is a collection of conceptually similar functions that provide services to the layer above it and receives service from the layer below it. Description of OSI layers: Layer 1: Physical Layer ·         Defines the electrical and physical specifications for devices. In particular, it defines the relationship between a device and a physical medium. ·         Establishment and termination of a connection to a communications medium. ·         Participation in the process whereby the communication resources are effectively shared among multiple users. ·         Modulation or conversion between the representation of digital data in user equipment and the corresponding signals transmitted over a communications channel. Layer 2: Data Link Layer ·         Provides the functional and procedural means to transfer data between network entities. ·         Detect and possibly correct errors that may occur in the Physical Layer. The error check is performed using Frame Check Sequence (FCS). ·         Addresses is then sought to see if it needs to process the rest of the frame itself or whether to pass it on to another host. ·         The Layer is divided into two sub layers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. ·         MAC sub layer controls how a computer on the network gains access to the data and permission to transmit it. ·         LLC layer controls frame synchronization, flow control and error checking.   Layer 3: Network Layer ·         Provides the functional and procedural means of transferring variable length data sequences from a source to a destination via one or more networks. ·         Performs network routing functions, and might also perform fragmentation and reassembly, and report delivery errors. ·         Network Layer Routers operate at this layer—sending data throughout the extended network and making the Internet possible.   Layer 4: Transport Layer ·         Provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers. ·         Controls the reliability of a given link through flow control, segmentation/de-segmentation, and error control. ·         Transport Layer can keep track of the segments and retransmit those that fail. Layer 5: Session Layer ·         Controls the dialogues (connections) between computers. ·         Establishes, manages and terminates the connections between the local and remote application. ·         Provides for full-duplex, half-duplex, or simplex operation, and establishes checkpointing, adjournment, termination, and restart procedures. ·         Implemented explicitly in application environments that use remote procedure calls. Layer 6: Presentation Layer ·         Establishes a context between Application Layer entities, in which the higher-layer entities can use different syntax and semantics, as long as the presentation service understands both and the mapping between them. The presentation service data units are then encapsulated into Session Protocol data units, and moved down the stack. ·         Provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. The presentation layer works to transform data into the form that the application layer can accept. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer. Layer 7: Application Layer ·         This layer interacts with software applications that implement a communicating component. ·         Identifies communication partners, determines resource availability, and synchronizes communication. o       When identifying communication partners, the application layer determines the identity and availability of communication partners for an application with data to transmit. o       When determining resource availability, the application layer must decide whether sufficient network or the requested communication exists. o       In synchronizing communication, all communication between applications requires cooperation that is managed by the application layer. Technorati Tags: Kunal,OSI,Networking

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  • Bancassurers Seek IT Solutions to Support Distribution Model

    - by [email protected]
    Oracle Insurance's director of marketing for EMEA, John Sinclair, attended the third annual Bancassurance Forum in Vienna last month. He reports that the outlook for bancassurance in EMEA remains positive, despite changing market conditions that have led a number of bancassurers to re-examine their business models. Vienna is at the crossroads between mature Western European markets, where bancassurance is now an established best practice, and more recently tapped Eastern European markets that offer the greatest growth potential. Attendance at the Bancassurance Forum was good, with 87 bancassurance attendees, most in very senior positions in the industry. The conference provided the chance for a lively discussion among bancassurers looking to keep abreast of the latest trends in one of Europe's most successful distribution models for insurance. Even under normal business conditions, there is a great demand for best practice sharing within the industry as there is no standard formula for success.  Each company has to chart its own course and choose the strategies for sales, products development and the structure of ownership that make sense for their business, and as soon as they get it right bancassurers need to adapt the mix to keep up with ever changing regulations, completion and economic conditions.  To optimize the overall relationship between banking and insurance for mutual benefit, a balance needs to be struck between potentially conflicting interests. The banking side of the house is looking for greater wallet share from its customers and the ability to increase profitability by bundling insurance products with higher margins - especially in light of the recent economic crisis, where margins for traditional banking products are low and completion high. The insurance side of the house seeks access to new customers through a complementary distribution channel that is efficient and cost effective. To make the relationship work, it is important that both sides of the same house forge strategic and long term relationships - irrespective of whether the underlying business model is supported by a distribution agreement, cross-ownership or other forms of capital structure. However, this third annual conference was not held under normal business conditions. The conference took place in challenging, yet interesting times. ING's forced spinoff of its insurance operations under pressure by the EU Commission and the troubling losses suffered by Allianz as a result of the Dresdner bank sale were fresh in everyone's mind. One year after markets crashed, there is now enough hindsight to better understand the implications for bancassurance and best practices that are emerging to deal with them. The loan-driven business that has been crucial to bancassurance up till now evaporated during the crisis, leaving bancassurers grappling with how to change their overall strategy from a loan-driven to a more diversified model.  Attendees came to the conference to learn what strategies were working - not only to cope with the market shift, but to take advantage of it as markets pick up. Over the course of 14 customer case studies and numerous analyst presentations, topical issues ranging from getting the business model right to the impact on capital structuring of Solvency II were debated openly. Many speakers alluded to the need to specifically design insurance products with the banking distribution channel in mind, which brings with it specific requirements such as a high degree of standardization to achieve efficiency and reduce training costs. Moreover, products must be engineered to suit end consumers who consider banks a one-stop shop. The importance of IT to the successful implementation of bancassurance strategies was a theme that surfaced regularly throughout the conference.  The cross-selling opportunity - that will ultimately determine the success or failure of any bancassurance model - can only be fully realized through a flexible IT architecture that enables banking and insurance processes to be integrated and presented to front-line staff through a common interface. However, the reality is that most bancassurers have legacy IT systems, which constrain the businesses' ability to implement new strategies to maintaining competitiveness in turbulent times. My colleague Glenn Lottering, who chaired the conference, believes that the primary opportunities for bancassurers to extract value from their IT infrastructure investments lie in distribution management, risk management with the advent of Solvency II, and achieving operational excellence. "Oracle is ideally suited to meet the needs of bancassurance," Glenn noted, "supplying market-leading software for both banking and insurance. Oracle provides adaptive systems that let customers easily integrate hybrid business processes from both worlds while leveraging existing IT infrastructure." Overall, the consensus at the conference was that the outlook for bancassurance in EMEA remains positive, despite changing market conditions that have led a number of bancassurers to re-examine their business models. John Sinclair is marketing director for Oracle Insurance in EMEA. He has more than 20 years of experience in insurance and financial services.    

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  • How to save data from model without any association in cakephp [on hold]

    - by Abhishek
    I have base model in that i use dataManipulation method for updation in my code ,so i want to save data in receipt, receiptline model also in OpeningBankStatement.but i create association for receipt and receiptline not for OpeningBankStatement. So i want to save data this OpeningBankStatement model without any association.my demo code is. Array ( [Receipt] => Array ( [ID] => 566 [ObjectType] => 84 [TXNName] => bbnm [TXNDate] => 03-06-2014 [BranchID] => 1 [Narration1] => 267 [Narration] => Cheque Received [ExecutiveID] => 805 [AccountType] => 104 [Account] => 68 [ReferenceNo] => [TXNCurrencyID] => 3 [ExchangeRate] => 1.00000 [ManualAdiustment] => 0 [RevisionNumber] => 1 [CompanyID] => 1 [Status] => 633 ) [ReceiptLine] => Array ( [0] => Array ( [TXNID] => 566 [LineNo] => 0 [LineType_072] => 429 [BranchID] => 1 [AccountID] => 68 [ContactID] => [Amount] => 0 [CancelAmount] => 0 [OpenAmount] => 0 [Narration] => Cheque Received [CreatedBy] => 229 [ModifiedBy] => 229 [CreatedDate] => 2014-06-03 00:00:00 [ModifiedDate] => 2014-06-03 00:00:00 [Status] => 1 [RevisionNumber] => 1 [RowState] => [tmpInstrumentDate] => ) [1] => Array ( [LineNo] => 0 [RowState] => 436 [TXNID] => 0 [BranchID] => 1 [ContactID] => [AccountID] => 68 [Narration] => Cheque Received [Amount] => 0 [RevisionNumber] => 1 [LineType_072] => 460 [CancelAmount] => 0 [OpenAmount] => 0 [Status] => 1 ) ) [OpeningBankStatement] => Array ( [ObjectType] => 131 [TXNSeries] => 1 [TXNNo] => 12345 [TXNName] => bbnm [TXNDate] => 03-06-2014 [CompanyID] => 1 [AccountID] => 68 [ExecutiveID] => 805 [Narration] => Cheque Received [ReferenceNo] => [ParentObjectType] => 84 [ParentTXNID] => 1 [CancelledBy] => 1 [CancelledDate] => 2014-02-02 [CancellationRemarks] => hfg [Status] => 1 [RevisionNumber] => 1 ) ) By any dyanamic model association or callback method it solve? suggest solution.

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  • Sys.WebForms.PageRequestManagerServerErrorException: An entity object cannot be referenced by multiple instances of IEntityChangeTracker [closed]

    - by Mingebag
    `Story: I have a strange error when I try to save something I got this error message An entity object cannot be referenced by multiple instances of IEntityChangeTracker. I really don’t know what that is and why is it appear, it appears only when I try to save something my insert and update is working, only when I try to save something in db from my Telerik grid if (this.annualVacationList != null) { List<AnnualVacation> vacationToSave = this.annualVacationList; IEnumerable<AnnualVacation> existing = paramUser.AnnualVacations; foreach (AnnualVacation toSave in vacationToSave) { AnnualVacation existingItem = existing.Where(x => x.AnnualVacationId == toSave.AnnualVacationId).SingleOrDefault(); if (existingItem == null) { ctx.AddToAnnualVacations(toSave); } else { existingItem.FromDate = toSave.FromDate; existingItem.ToDate = toSave.ToDate; existingItem.WorkingTime = toSave.WorkingTime; existingItem.VacationDays = toSave.VacationDays; } } } ctx.SaveChanges(); } After debugging I have seen that the code brake down in the Project.Name.Designer.cs ..... O.o public void AddToAnnualVacations(AnnualVacation annualVacation) { base.AddObject("AnnualVacations", annualVacation); }

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  • How do you model roles / relationships with Domain Driven Design in mind?

    - by kitsune
    If I have three entities, Project, ProjectRole and Person, where a Person can be a member of different Projects and be in different Project Roles (such as "Project Lead", or "Project Member") - how would you model such a relationship? In the database, I currently have the following tablers: Project, Person, ProjectRole Project_Person with PersonId & ProjectId as PK and a ProjectRoleId as a FK Relationship. I'm really at a loss here since all domain models I come up with seem to break some "DDD" rule. Are there any 'standards' for this problem? I had a look at a Streamlined Object Modeling and there is an example what a Project and ProjectMember would look like, but AddProjectMember() in Project would call ProjectMember.AddProject(). So Project has a List of ProjectMembers, and each ProjectMember in return has a reference to the Project. Looks a bit convoluted to me. update After reading more about this subject, I will try the following: There are distinct roles, or better, model relationships, that are of a certain role type within my domain. For instance, ProjectMember is a distinct role that tells us something about the relationship a Person plays within a Project. It contains a ProjectMembershipType that tells us more about the Role it will play. I do know for certain that persons will have to play roles inside a project, so I will model that relationship. ProjectMembershipTypes can be created and modified. These can be "Project Leader", "Developer", "External Adviser", or something different. A person can have many roles inside a project, and these roles can start and end at a certain date. Such relationships are modeled by the class ProjectMember. public class ProjectMember : IRole { public virtual int ProjectMemberId { get; set; } public virtual ProjectMembershipType ProjectMembershipType { get; set; } public virtual Person Person { get; set; } public virtual Project Project { get; set; } public virtual DateTime From { get; set; } public virtual DateTime Thru { get; set; } // etc... } ProjectMembershipType: ie. "Project Manager", "Developer", "Adviser" public class ProjectMembershipType : IRoleType { public virtual int ProjectMembershipTypeId { get; set; } public virtual string Name { get; set; } public virtual string Description { get; set; } // etc... }

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  • Entity Framework in n-layered application - Lazy loading vs. Eager loading patterns

    - by Marconline
    Hi all. This questions doesn't let me sleep as it's since one year I'm trying to find a solution but... still nothing happened in my mind. Probably you can help me, because I think this is a very common issue. I've a n-layered application: presentation layer, business logic layer, model layer. Suppose for simplicity that my application contains, in the presentation layer, a form that allows a user to search for a customer. Now the user fills the filters through the UI and clicks a button. Something happens and the request arrives to presentation layer to a method like CustomerSearch(CustomerFilter myFilter). This business logic layer now keeps it simple: creates a query on the model and gets back results. Now the question: how do you face the problem of loading data? I mean business logic layer doesn't know that that particular method will be invoked just by that form. So I think that it doesn't know if the requesting form needs just the Customer objects back or the Customer objects with the linked Order entities. I try to explain better: our form just wants to list Customers searching by surname. It has nothing to do with orders. So the business logic query will be something like: (from c in ctx.CustomerSet where c.Name.Contains(strQry) select c).ToList(); now this is working correctly. Two days later your boss asks you to add a form that let you search for customers like the other and you need to show the total count of orders created by each customer. Now I'd like to reuse that query and add the piece of logic that attach (includes) orders and gets back that. How would you front this request? Here is the best (I think) idea I had since now. I'd like to hear from you: my CustomerSearch method in BLL doesn't create the query directly but passes through private extension methods that compose the ObjectQuery like: private ObjectQuery<Customer> SearchCustomers(this ObjectQuery<Customer> qry, CustomerFilter myFilter) and private ObjectQuery<Customer> IncludeOrders(this ObjectQuery<Customer> qry) but this doesn't convince me as it seems too complex. Thanks, Marco

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  • How do I get the Zend_Application's database into a model class?

    - by Billy ONeal
    I have a Zend_Framework application, which has a whole bunch of model classes. I need these model classes to be able to access the application's database (naturally). Currently I've put this in my index.php: Zend_Registry::set('db', $application->bootstrap()->getBootstrap() ->getPluginResource('db')->getDbAdapter()); And then $db = Zend_Registry::get('db'); in each of my model classes that require the database. But this seems like a horrible horrible hack. Am I missing something basic here?

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  • Is this type of calculation to be put in Model or Controller?

    - by Hadi
    i have Product and SalesOrder model (to simplify, 1 sales_order only for 1 product) Product has_many SalesOrder SalesOrder belongs_to Product pa = Product A #2000 so1 = SalesOrder 1 order product A #1000, date:yesterday so2 = SalesOrder 2 order product A #999, date:yesterday so3 = SalesOrder 3 order product A #1000, date:now Based on the date, pa.find_sales_orders_that_can_be_delivered will give: SalesOrder 1 order product A #1000, date:yesterday SalesOrder 2 order product A #999, date:yesterday SalesOrder 3 order product A #1, date:now <-- the newest The question is: is find_sales_orders_that_can_be_delivered should be in the Model? i can do it in controller. and the general question is: what goes in Model and what goes in Controller. Thank you

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  • Child transforms problem when loading 3DS models using assimp

    - by MhdSyrwan
    I'm trying to load a textured 3d model into my scene using assimp model loader. The problem is that child meshes are not situated correctly (they don't have the correct transformations). In brief: all the mTansform matrices are identity matrices, why would that be? I'm using this code to render the model: void recursive_render (const struct aiScene *sc, const struct aiNode* nd, float scale) { unsigned int i; unsigned int n=0, t; aiMatrix4x4 m = nd->mTransformation; m.Scaling(aiVector3D(scale, scale, scale), m); // update transform m.Transpose(); glPushMatrix(); glMultMatrixf((float*)&m); // draw all meshes assigned to this node for (; n < nd->mNumMeshes; ++n) { const struct aiMesh* mesh = scene->mMeshes[nd->mMeshes[n]]; apply_material(sc->mMaterials[mesh->mMaterialIndex]); if (mesh->HasBones()){ printf("model has bones"); abort(); } if(mesh->mNormals == NULL) { glDisable(GL_LIGHTING); } else { glEnable(GL_LIGHTING); } if(mesh->mColors[0] != NULL) { glEnable(GL_COLOR_MATERIAL); } else { glDisable(GL_COLOR_MATERIAL); } for (t = 0; t < mesh->mNumFaces; ++t) { const struct aiFace* face = &mesh->mFaces[t]; GLenum face_mode; switch(face->mNumIndices) { case 1: face_mode = GL_POINTS; break; case 2: face_mode = GL_LINES; break; case 3: face_mode = GL_TRIANGLES; break; default: face_mode = GL_POLYGON; break; } glBegin(face_mode); for(i = 0; i < face->mNumIndices; i++)// go through all vertices in face { int vertexIndex = face->mIndices[i];// get group index for current index if(mesh->mColors[0] != NULL) Color4f(&mesh->mColors[0][vertexIndex]); if(mesh->mNormals != NULL) if(mesh->HasTextureCoords(0))//HasTextureCoords(texture_coordinates_set) { glTexCoord2f(mesh->mTextureCoords[0][vertexIndex].x, 1 - mesh->mTextureCoords[0][vertexIndex].y); //mTextureCoords[channel][vertex] } glNormal3fv(&mesh->mNormals[vertexIndex].x); glVertex3fv(&mesh->mVertices[vertexIndex].x); } glEnd(); } } // draw all children for (n = 0; n < nd->mNumChildren; ++n) { recursive_render(sc, nd->mChildren[n], scale); } glPopMatrix(); } What's the problem in my code ? I've added some code to abort the program if there's any bone in the meshes, but the program doesn't abort, this means : no bones, is that normal? if (mesh->HasBones()){ printf("model has bones"); abort(); } Note: I am using openGL & SFML & assimp

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  • Doctrine: Relating a model to itself using a link table, like "This event is related to to the following other events"

    - by mattalexx
    So in English, the relationship would sound like "This event is related to to the following other events". My first instinct is to create an EventEvent model, with a first_event_id field and a second_event_id field. Then I would define the following two relationships in the Event model: $this->hasMany('Event as FirstRelatedEvents', array('local' => 'first_event_id', 'foreign' => 'second_event_id', 'refClass' => 'EventEvent')); $this->hasMany('Event as SecondRelatedEvents', array('local' => 'second_event_id', 'foreign' => 'first_event_id', 'refClass' => 'EventEvent')); But I would rather not have to use two relationships on the Event model. Is there a better way to do this?

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  • In MVC framworks (such as Ruby on Rails), does usually Model spell as singular and controller and vi

    - by Jian Lin
    I usually see Ruby on Rails books using script/generate model Story name:string link:string which is a singular Story, while when it is controller script/generate controller Stories index then the Story now is Stories, which is plural. Is this a standard on Ruby on Rails? Is it true in other MVC frameworks too, like CakePHP, Symfony, Django, or TurboGears? I see that in the book Rails Space, the controller is also called User, which is the same as the model name, and it is the only exception I see. Update: also, when scaffold is done on Ruby on Rails, then automatically, the model is singular and the controller and view are both plural.

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  • Should I call redirect() from within my Controller or Model in an MVC framework?

    - by justinl
    I'm using the MVC PHP framework Codeigniter and I have a straight forward question about where to call redirect() from: Controller or Model? Scenario: A user navigates to www.example.com/item/555. In my Model I search the item database for an item with the ID of 555. If I find the item, I'll return the result to my controller. However, if an item is not found, I want to redirect the user somewhere. Should this call to redirect() come from inside the model or the controller? Why?

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  • ECS with Go - circular imports [migrated]

    - by Andreas
    I'm exploring both Go and Entity-Component-Systems. I understand how ECS works, and I'm trying to replicate what seems to be the go-to document of ECS, namely http://cowboyprogramming.com/2007/01/05/evolve-your-heirachy/ For performance, the document recommends to use static arrays of every component type. That is, not arrays of component interfaces (arrays of pointers). The problem with this in Go is circular imports. I have one package, ecs, which contains the definitions for Entity, Component and System types/interfaces as well as an EntityManager. Another package, ecs/components, contains the various components. Obviously, the ecs/components package depends on ecs. But, to declare arrays of specific components in EntityManager, ecs would depend on ecs/components, therefore creating a circular import. Is there any way of avoiding this? I am aware that normally a high level system should not depend on lower systems. I'm also want to point out that using an array of pointers is probably fast enough for my purposes, but I'm interested in possible workarounds (for future reference) Thank you for your help!

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  • what's a good approach to working with multiple databases?

    - by Riz
    I'm working on a project that has its own database call it InternalDb, but also it queries two other databases, call them ExternalDb1 and ExternalDb2. Both ExternalDb1 and ExternalDb2 are actually required by a few other projects. I'm wondering what the best approach for dealing with this is? Currently, I've just created a project for each of these external databases and then generated Edmx and entities using the entity-framework approach. My thought was that I could then include these projects in any of my solutions that require access to these databases. Also, I don't have any separate business layers. I just have a solution like below: Project.Domain ExternalDb1Project.Domain ExternalDb2Project.Domain Project.Web So my Domain projects contain the data access as well as the POCOs generated by Entity Framework and any business logic. But I'm not sure if this is a good approach. For example if I want to do Validation in my Project.Domain on the entities in the InternalDb, it's fine. But if I want to do Validation for entities from either of the ExternalDbs, then I wonder where it should go? To be more specific, I retrieve Employees from ExternalDb1Project.Domain. However, I want to make sure they are Active. Where should this Validation go? How to architect a project like this at a high level? Also, I want to make sure that I use IoC for my data contexts so I can create Fakes when writing tests. I wonder where the interfaces for these various data contexts would reside?

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  • What's the difference between the box-model bug and the new box-sizing CSS?

    - by RKS
    In days (long past for some, and still present for others) the box-model bug was a bane to their existence. The idea that an element's width included the margin, border, and padding was blasphemous and an abomination to their senses. So we got away from it after thousands of internet blogs about the box-model hack. Now we get box-sizing, which will, wait for it, allow you to specify that a width contains the border, the margin, and the padding. We plaster a trendy new name for it, "CSS3 Flexbox," and now it's the freedom designers have been looking for. For those logical people who saw the box-model bug as not the bug and the W3C as the actual bug, this comes as a surprise. A reintroduction of this so-called bug and now we call it an enhancement? So can someone explain why this is different? I am honestly confused about this.

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  • What's wrong performing unit test against concrete implementation if your frameworks are not going to change?

    - by palm snow
    First a bit of background: We are re-architecting our product suite that was written 10 years ago and served its purpose. One thing that we cannot change is the database schema as we have 500+ client base using this system. Our db schema has over 150+ tables. We have decided on using Entity Framework 4.1 as DAL and still evaluating various frameworks for storing our business logic. I am investigation to bring unit testing into the mix but I also confused as to how far I need to go with setting up a full blown TDD environment. One aspect of setting up unit testing is by getting into implementing Repository, unit of work and mocking frameworks etc. This mean there will be cost and investment on the code-bloat associated with all these frameworks. I understand some of this could be auto-generated but when it comes to things like behaviors, that will be mostly hand written. Just to be clear, I am not questioning the important of unit testing your code. I am just not sure we need all its components (like repository, mocking etc.) when we are fairly certain of storage mechanism/framework (SQL Server/Entity Framework). All that code bloat with generic repositories make sense when you need a generic layers with ability to change this whenever you like however its very likely a YAGNI in our case. What we need is more of integration testing where we can unit-test our code with concrete repository objects and test data in database. In this scenario, just running integration test seem to be more beneficial in our case. Any thoughts if I am missing any thing here?

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  • Getting Error whileInitializing entities [closed]

    - by R76
    I am new'b as WPF Dev. I am developing Window application in WPF using mvvmlight framework. I have created database in Sqlserver compact 4.0. I have made a Ado.net Entity Data Model. When I trying to initialize the Entity object in service it throws the error like: Error 'The invocation of the constructor on type 'PointOfSale.ViewModels.ProductsViewModel' that matches the specified binding constraints threw an exception.' Line number '7' and line position '10'. stack Trace at System.Windows.Markup.XamlReader.RewrapException(Exception e, IXamlLineInfo lineInfo, Uri baseUri) at System.Windows.Markup.WpfXamlLoader.Load(XamlReader xamlReader, IXamlObjectWriterFactory writerFactory, Boolean skipJournaledProperties, Object rootObject, XamlObjectWriterSettings settings, Uri baseUri) at System.Windows.Markup.WpfXamlLoader.LoadBaml(XamlReader xamlReader, Boolean skipJournaledProperties, Object rootObject, XamlAccessLevel accessLevel, Uri baseUri) at System.Windows.Markup.XamlReader.LoadBaml(Stream stream, ParserContext parserContext, Object parent, Boolean closeStream) at System.Windows.Application.LoadComponent(Object component, Uri resourceLocator) at PointOfSale.MainWindow.InitializeComponent() in e:\VarniApplication\PointOfSale\PointOfSale\MainWindow.xaml:line 1 at PointOfSale.MainWindow..ctor() in E:\VarniApplication\PointOfSale\PointOfSale\MainWindow.xaml.cs:line 27 Inner Exception {"Unable to load the specified metadata resource."} My code: xyzEntities entites; public ctor() { entites = new xyzEntities(); //This line throws an error } I have installed sql server compact 4.0 from web installer 3.0. and added the sql server compact toolbox from the extension manager. Tell me if I am missing something to install or missing something to write code.

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  • knowing all available entity types

    - by plofplof
    I'm making a game where at some point the game will create enemies of random types. Each type of enemy available is defined on its own class derived from an enemy superclass. To do this, obviously the different types of enemies should be known. This is what I have thought of: Just make a list manually. Very simple to do, but I don't like it because I'll be adding more enemy types over time, so any time I add a new class I have to remember to update this (same if I remove an enemy). I would like some kind of auto-updating list. A completely component based system. There are no different classes for each enemy, but definitions of enemies in some file where all enemy types can be found. I really don't need that level of complexity for my game. I'm still using a component based model to some degree, but each Enemy type gets defined on its own class. Java Annotation processing. Give each enemy subclass an annotation like @EnemyType("whatever"), then code an annotation processor that writes in a file all available enemy types. Any time a new class is added the file gets updated after compilation.This gives me a feeling of failure even if its a good solution, it's very dependant on Java, so it means I cant think of a general design good for any kind of language. Also I think that this would be too much work for something so simple. I would like to see comments on these ideas and other possible solutions Thanks

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  • Updating an Entity through a Service

    - by GeorgeK
    I'm separating my software into three main layers (maybe tiers would be a better term): Presentation ('Views') Business logic ('Services' and 'Repositories') Data access ('Entities' (e.g. ActiveRecords)) What do I have now? In Presentation, I use read-only access to Entities, returned from Repositories or Services, to display data. $banks = $banksRegistryService->getBanksRepository()->getBanksByCity( $city ); $banksViewModel = new PaginatedList( $banks ); // some way to display banks; // example, not real code I find this approach quite efficient in terms of performance and code maintanability and still safe as long as all write operations (create, update, delete) are preformed through a Service: namespace Service\BankRegistry; use Service\AbstractDatabaseService; use Service\IBankRegistryService; use Model\BankRegistry\Bank; class Service extends AbstractDatabaseService implements IBankRegistryService { /** * Registers a new Bank * * @param string $name Bank's name * @param string $bik Bank's Identification Code * @param string $correspondent_account Bank's correspondent account * * @return Bank */ public function registerBank( $name, $bik, $correspondent_account ) { $bank = new Bank(); $bank -> setName( $name ) -> setBik( $bik ) -> setCorrespondentAccount( $correspondent_account ); if( null === $this->getBanksRepository()->getDefaultBank() ) $this->setDefaultBank( $bank ); $this->getEntityManager()->persist( $bank ); return $bank; } /** * Makes the $bank system's default bank * * @param Bank $bank * @return IBankRegistryService */ public function setDefaultBank( Bank $bank ) { $default_bank = $this->getBanksRepository()->getDefaultBank(); if( null !== $default_bank ) $default_bank->setDefault( false ); $bank->setDefault( true ); return $this; } } Where am I stuck? I'm struggling about how to update certain fields in Bank Entity. Bad solution #1: Making a series of setters in Service for each setter in Bank; - seems to be quite reduntant, increases Service interface complexity and proportionally decreases it's simplicity - something to avoid if you care about code maitainability. I try to follow KISS and DRY principles. Bad solution #2: Modifying Bank directly through it's native setters; - really bad. If you'll ever need to move modification into the Service, it will be pain. Business logic should remain in Business logic layer. Plus, there are plans on logging all of the actions and maybe even involve user permissions (perhaps, through decorators) in future, so all modifications should be made only through the Service. Possible good solution: Creating an updateBank( Bank $bank, $array_of_fields_to_update) method; - makes the interface as simple as possible, but there is a problem: one should not try to manually set isDefault flag on a Bank, this operation should be performed through setDefaultBank method. It gets even worse when you have relations that you don't want to be directly modified. Of course, you can just limit the fields that can be modified by this method, but how do you tell method's user what they can and cannot modify? Exceptions?

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  • MVC 3 Client Validation works intermittently

    - by Gutek
    I have MVC 3 version, System.Web.Mvc product version is: 3.0.20105.0 modified on 5th of Jan 2011 - i think that's the latest. I’ve notice that client validation is not working as it suppose in the application that we are creating, so I’ve made a quick test. I’ve created basic MVC 3 Application using Internet Application template. I’ve added Test Controller: using System.Web.Mvc; using MvcApplication3.Models; namespace MvcApplication3.Controllers { public class TestController : Controller { public ActionResult Index() { return View(); } public ActionResult Create() { Sample model = new Sample(); return View(model); } [HttpPost] public ActionResult Create(Sample model) { if(!ModelState.IsValid) { return View(); } return RedirectToAction("Display"); } public ActionResult Display() { Sample model = new Sample(); model.Age = 10; model.CardNumber = "1324234"; model.Email = "[email protected]"; model.Title = "hahah"; return View(model); } } } Model: using System.ComponentModel.DataAnnotations; namespace MvcApplication3.Models { public class Sample { [Required] public string Title { get; set; } [Required] public string Email { get; set; } [Required] [Range(4, 120, ErrorMessage = "Oi! Common!")] public short Age { get; set; } [Required] public string CardNumber { get; set; } } } And 3 views: Create: @model MvcApplication3.Models.Sample @{ ViewBag.Title = "Create"; Layout = "~/Views/Shared/_Layout.cshtml"; } <h2>Create</h2> <script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script> @*@{ Html.EnableClientValidation(); }*@ @using (Html.BeginForm()) { @Html.ValidationSummary(false) <fieldset> <legend>Sample</legend> <div class="editor-label"> @Html.LabelFor(model => model.Title) </div> <div class="editor-field"> @Html.EditorFor(model => model.Title) @Html.ValidationMessageFor(model => model.Title) </div> <div class="editor-label"> @Html.LabelFor(model => model.Email) </div> <div class="editor-field"> @Html.EditorFor(model => model.Email) @Html.ValidationMessageFor(model => model.Email) </div> <div class="editor-label"> @Html.LabelFor(model => model.Age) </div> <div class="editor-field"> @Html.EditorFor(model => model.Age) @Html.ValidationMessageFor(model => model.Age) </div> <div class="editor-label"> @Html.LabelFor(model => model.CardNumber) </div> <div class="editor-field"> @Html.EditorFor(model => model.CardNumber) @Html.ValidationMessageFor(model => model.CardNumber) </div> <p> <input type="submit" value="Create" /> </p> </fieldset> @*<fieldset> @Html.EditorForModel() <p> <input type="submit" value="Create" /> </p> </fieldset> *@ } <div> @Html.ActionLink("Back to List", "Index") </div> Display: @model MvcApplication3.Models.Sample @{ ViewBag.Title = "Display"; Layout = "~/Views/Shared/_Layout.cshtml"; } <h2>Display</h2> <fieldset> <legend>Sample</legend> <div class="display-label">Title</div> <div class="display-field">@Model.Title</div> <div class="display-label">Email</div> <div class="display-field">@Model.Email</div> <div class="display-label">Age</div> <div class="display-field">@Model.Age</div> <div class="display-label">CardNumber</div> <div class="display-field">@Model.CardNumber</div> </fieldset> <p> @Html.ActionLink("Back to List", "Index") </p> Index: @{ ViewBag.Title = "Index"; Layout = "~/Views/Shared/_Layout.cshtml"; } <h2>Index</h2> <p> @Html.ActionLink("Create", "Create") </p> <p> @Html.ActionLink("Display", "Display") </p> Everything is default here – Create Controller, AddView from controller action with model specified with proper scaffold template and using provided layout in sample application. When I will go to /Test/Create client validation in most cases works only for Title and Age fields, after clicking Create it works for all fields (create does not goes to server). However in some cases (after a build) Title validation is not working and Email is, or CardNumber or Title and CardNumber but Email is not. But never all validation is working before clicking Create. I’ve tried creating form with Html.EditorForModel as well as enforce client validation just before BeginForm: @{ Html.EnableClientValidation(); } I’m providing a source code for this sample on dropbox – as maybe our dev env is broken :/ I’ve done tests on IE 8 and Chrome 10 beta. Just in case, in web config validation scripts are enabled: <appSettings> <add key="ClientValidationEnabled" value="true"/> <add key="UnobtrusiveJavaScriptEnabled" value="true"/> </appSettings> So my questions are Is there a way to ensure that Client validation will work as it supposed to work and not intermittently? Is this a desired behavior and I'm missing something in configuration/implementation?

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  • Backbone.js Adding Model to Collection Issue

    - by jtmgdevelopment
    I am building a test application in Backbone.js (my first app using Backbone). The app goes like this: Load Data from server "Plans" Build list of plans and show to screen There is a button to add a new plan Once new plan is added, add to collection ( do not save to server as of now ) redirect to index page and show the new collection ( includes the plan you just added) My issue is with item 5. When I save a plan, I add the model to the collection then redirect to the initial view. At this point, I fetch data from the server. When I fetch data from the server, this overwrites my collection and my added model is gone. How can I prevent this from happening? I have found a way to do this but it is definitely not the correct way at all. Below you will find my code examples for this. Thanks for the help. PlansListView View: var PlansListView = Backbone.View.extend({ tagName : 'ul', initialize : function() { _.bindAll( this, 'render', 'close' ); //reset the view if the collection is reset this.collection.bind( 'reset', this.render , this ); }, render : function() { _.each( this.collection.models, function( plan ){ $( this.el ).append( new PlansListItemView({ model: plan }).render().el ); }, this ); return this; }, close : function() { $( this.el ).unbind(); $( this.el ).remove(); } });//end NewPlanView Save Method var NewPlanView = Backbone.View.extend({ tagName : 'section', template : _.template( $( '#plan-form-template' ).html() ), events : { 'click button.save' : 'savePlan', 'click button.cancel' : 'cancel' }, intialize: function() { _.bindAll( this, 'render', 'save', 'cancel' ); }, render : function() { $( '#container' ).append( $( this.el ).html(this.template( this.model.toJSON() )) ); return this; }, savePlan : function( event ) { this.model.set({ name : 'bad plan', date : 'friday', desc : 'blah', id : Math.floor(Math.random()*11), total_stops : '2' }); this.collection.add( this.model ); app.navigate('', true ); event.preventDefault(); }, cancel : function(){} }); Router (default method): index : function() { this.container.empty(); var self = this; //This is a hack to get this to work //on default page load fetch all plans from the server //if the page has loaded ( this.plans is defined) set the updated plans collection to the view //There has to be a better way!! if( ! this.plans ) { this.plans = new Plans(); this.plans.fetch({ success: function() { self.plansListView = new PlansListView({ collection : self.plans }); $( '#container' ).append( self.plansListView.render().el ); if( self.requestedID ) self.planDetails( self.requestedID ); } }); } else { this.plansListView = new PlansListView({ collection : this.plans }); $( '#container' ).append( self.plansListView.render().el ); if( this.requestedID ) self.planDetails( this.requestedID ); } }, New Plan Route: newPlan : function() { var plan = new Plan({name: 'Cool Plan', date: 'Monday', desc: 'This is a great app'}); this.newPlan = new NewPlanView({ model : plan, collection: this.plans }); this.newPlan.render(); } FULL CODE ( function( $ ){ var Plan = Backbone.Model.extend({ defaults: { name : '', date : '', desc : '' } }); var Plans = Backbone.Collection.extend({ model : Plan, url : '/data/' }); $( document ).ready(function( e ){ var PlansListView = Backbone.View.extend({ tagName : 'ul', initialize : function() { _.bindAll( this, 'render', 'close' ); //reset the view if the collection is reset this.collection.bind( 'reset', this.render , this ); }, render : function() { _.each( this.collection.models, function( plan ){ $( this.el ).append( new PlansListItemView({ model: plan }).render().el ); }, this ); return this; }, close : function() { $( this.el ).unbind(); $( this.el ).remove(); } });//end var PlansListItemView = Backbone.View.extend({ tagName : 'li', template : _.template( $( '#list-item-template' ).html() ), events :{ 'click a' : 'listInfo' }, render : function() { $( this.el ).html( this.template( this.model.toJSON() ) ); return this; }, listInfo : function( event ) { } });//end var PlanView = Backbone.View.extend({ tagName : 'section', events : { 'click button.add-plan' : 'newPlan' }, template: _.template( $( '#plan-template' ).html() ), initialize: function() { _.bindAll( this, 'render', 'close', 'newPlan' ); }, render : function() { $( '#container' ).append( $( this.el ).html( this.template( this.model.toJSON() ) ) ); return this; }, newPlan : function( event ) { app.navigate( 'newplan', true ); }, close : function() { $( this.el ).unbind(); $( this.el ).remove(); } });//end var NewPlanView = Backbone.View.extend({ tagName : 'section', template : _.template( $( '#plan-form-template' ).html() ), events : { 'click button.save' : 'savePlan', 'click button.cancel' : 'cancel' }, intialize: function() { _.bindAll( this, 'render', 'save', 'cancel' ); }, render : function() { $( '#container' ).append( $( this.el ).html(this.template( this.model.toJSON() )) ); return this; }, savePlan : function( event ) { this.model.set({ name : 'bad plan', date : 'friday', desc : 'blah', id : Math.floor(Math.random()*11), total_stops : '2' }); this.collection.add( this.model ); app.navigate('', true ); event.preventDefault(); }, cancel : function(){} }); var AppRouter = Backbone.Router.extend({ container : $( '#container' ), routes : { '' : 'index', 'viewplan/:id' : 'planDetails', 'newplan' : 'newPlan' }, initialize: function(){ }, index : function() { this.container.empty(); var self = this; //This is a hack to get this to work //on default page load fetch all plans from the server //if the page has loaded ( this.plans is defined) set the updated plans collection to the view //There has to be a better way!! if( ! this.plans ) { this.plans = new Plans(); this.plans.fetch({ success: function() { self.plansListView = new PlansListView({ collection : self.plans }); $( '#container' ).append( self.plansListView.render().el ); if( self.requestedID ) self.planDetails( self.requestedID ); } }); } else { this.plansListView = new PlansListView({ collection : this.plans }); $( '#container' ).append( self.plansListView.render().el ); if( this.requestedID ) self.planDetails( this.requestedID ); } }, planDetails : function( id ) { if( this.plans ) { this.plansListView.close(); this.plan = this.plans.get( id ); if( this.planView ) this.planView.close(); this.planView = new PlanView({ model : this.plan }); this.planView.render(); } else{ this.requestedID = id; this.index(); } if( ! this.plans ) this.index(); }, newPlan : function() { var plan = new Plan({name: 'Cool Plan', date: 'Monday', desc: 'This is a great app'}); this.newPlan = new NewPlanView({ model : plan, collection: this.plans }); this.newPlan.render(); } }); var app = new AppRouter(); Backbone.history.start(); }); })( jQuery );

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