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  • How do I know if I need a layer 3 switch?

    - by eekmeter
    We currently have a flat network with a bunch of unmanaged switches. I would like to use VLANs to segregate certain users like guests and I would like to use 802.1x. However, I'm not sure if what I need is a layer 3 or a level 2 switch. From what I understand a layer 3 switch does routing between VLANs. I don't think I need this at the moment but as I said I'm not sure since this is all new to me. What else would a layer 3 switch do for me? Our network is relatively small, less than a 100 users. What exactly does a layer 3 switch do that I can't get with a layer 2 switch? When would I need a layer 3?

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  • How accurate is "Business logic should be in a service, not in a model"?

    - by Jeroen Vannevel
    Situation Earlier this evening I gave an answer to a question on StackOverflow. The question: Editing of an existing object should be done in repository layer or in service? For example if I have a User that has debt. I want to change his debt. Should I do it in UserRepository or in service for example BuyingService by getting an object, editing it and saving it ? My answer: You should leave the responsibility of mutating an object to that same object and use the repository to retrieve this object. Example situation: class User { private int debt; // debt in cents private string name; // getters public void makePayment(int cents){ debt -= cents; } } class UserRepository { public User GetUserByName(string name){ // Get appropriate user from database } } A comment I received: Business logic should really be in a service. Not in a model. What does the internet say? So, this got me searching since I've never really (consciously) used a service layer. I started reading up on the Service Layer pattern and the Unit Of Work pattern but so far I can't say I'm convinced a service layer has to be used. Take for example this article by Martin Fowler on the anti-pattern of an Anemic Domain Model: There are objects, many named after the nouns in the domain space, and these objects are connected with the rich relationships and structure that true domain models have. The catch comes when you look at the behavior, and you realize that there is hardly any behavior on these objects, making them little more than bags of getters and setters. Indeed often these models come with design rules that say that you are not to put any domain logic in the the domain objects. Instead there are a set of service objects which capture all the domain logic. These services live on top of the domain model and use the domain model for data. (...) The logic that should be in a domain object is domain logic - validations, calculations, business rules - whatever you like to call it. To me, this seemed exactly what the situation was about: I advocated the manipulation of an object's data by introducing methods inside that class that do just that. However I realize that this should be a given either way, and it probably has more to do with how these methods are invoked (using a repository). I also had the feeling that in that article (see below), a Service Layer is more considered as a façade that delegates work to the underlying model, than an actual work-intensive layer. Application Layer [his name for Service Layer]: Defines the jobs the software is supposed to do and directs the expressive domain objects to work out problems. The tasks this layer is responsible for are meaningful to the business or necessary for interaction with the application layers of other systems. This layer is kept thin. It does not contain business rules or knowledge, but only coordinates tasks and delegates work to collaborations of domain objects in the next layer down. It does not have state reflecting the business situation, but it can have state that reflects the progress of a task for the user or the program. Which is reinforced here: Service interfaces. Services expose a service interface to which all inbound messages are sent. You can think of a service interface as a façade that exposes the business logic implemented in the application (typically, logic in the business layer) to potential consumers. And here: The service layer should be devoid of any application or business logic and should focus primarily on a few concerns. It should wrap Business Layer calls, translate your Domain in a common language that your clients can understand, and handle the communication medium between server and requesting client. This is a serious contrast to other resources that talk about the Service Layer: The service layer should consist of classes with methods that are units of work with actions that belong in the same transaction. Or the second answer to a question I've already linked: At some point, your application will want some business logic. Also, you might want to validate the input to make sure that there isn't something evil or nonperforming being requested. This logic belongs in your service layer. "Solution"? Following the guidelines in this answer, I came up with the following approach that uses a Service Layer: class UserController : Controller { private UserService _userService; public UserController(UserService userService){ _userService = userService; } public ActionResult MakeHimPay(string username, int amount) { _userService.MakeHimPay(username, amount); return RedirectToAction("ShowUserOverview"); } public ActionResult ShowUserOverview() { return View(); } } class UserService { private IUserRepository _userRepository; public UserService(IUserRepository userRepository) { _userRepository = userRepository; } public void MakeHimPay(username, amount) { _userRepository.GetUserByName(username).makePayment(amount); } } class UserRepository { public User GetUserByName(string name){ // Get appropriate user from database } } class User { private int debt; // debt in cents private string name; // getters public void makePayment(int cents){ debt -= cents; } } Conclusion All together not much has changed here: code from the controller has moved to the service layer (which is a good thing, so there is an upside to this approach). However this doesn't look like it had anything to do with my original answer. I realize design patterns are guidelines, not rules set in stone to be implemented whenever possible. Yet I have not found a definitive explanation of the service layer and how it should be regarded. Is it a means to simply extract logic from the controller and put it inside a service instead? Is it supposed to form a contract between the controller and the domain? Should there be a layer between the domain and the service layer? And, last but not least: following the original comment Business logic should really be in a service. Not in a model. Is this correct? How would I introduce my business logic in a service instead of the model?

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  • Error: 175002 (RA layer request failed)

    - by BlindingDawn
    I get the following error when connecting XCode to a repository on GoogleCode.com Error: 175002 (RA layer request failed) Description: Server sent unexpected return value (405 Method Not Allowed) in response to OPTIONS request for 'http://touchcode.googlecode.com/hg' Has anyone see this before and how do I resolve it?

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  • Which layer implement Transaction mechanism

    - by didxga
    I knew ORM tools, such as Hibernate, have their own transaction management mechanism. We can also harness transaction by using JDBC directly. And DBMS has its transaction facilities either. I wonder that in which layer(s) the transaction is actually implemented in a J2EE application? Regards!

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  • How to implement service layer in Zend Framework?

    - by takeshin
    I'm looking for some good resources to learn how to implement internal service layer in Zend Framework. This is interesting post, but with no concrete code samples. Where to put service classes (/application/modules/modulename/services/?); How to autoload them (custom autoloader?) Most common services (user, authentication, cart, cache, feed?) Sample implementations (any github repos?) Good practices?

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  • How to add database layer in core data application

    - by aditya
    Hi all I am fairly new to core data technology and i searched a lot on how to add the database to a core data application.so can anybody guide me on how to integrate the database layer? i have seen the iphone tutorial on core data (i.e books example) but i am not able to understand how to .sqlite file has been included in that application

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  • presentation layer to go with apache torque

    - by ed1t
    I'm planning on using Apache torque as my object-relational mapper (ORM), and I was wondering if anybody has any suggestions around what framework to use for presentation layer with torque. maybe Spring? I don't know if this helps, but my application is basically going to be bunch of forms to input data and based on that data, I'll generate reports in form of a graph or chart.

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  • If we don't like it for the presentation layer, then why do we tolerate it for the behavior layer?

    - by greim
    Suppose CSS as we know it had never been invented, and the closest we could get was to do this: <script> // this is the page's stylesheet $(document).ready(function(){ $('.error').css({'color':'red'}); $('a[href]').css({'textDecoration':'none'}); ... }); </script> If this was how we were forced to write code, would we put up with it? Or would every developer on Earth scream at browser vendors until they standardized upon CSS, or at least some kind of declarative style language? Maybe CSS isn't perfect, but hopefully it's obvious how it's better than the find things, do stuff method shown above. So my question is this. We've seen and tasted of the glory of declarative binding with CSS, so why, when it comes to the behavioral/interactive layer, does the entire JavaScript community seem complacent about continuing to use the kludgy procedural method described above? Why for example is this considered by many to be the best possible way to do things: <script> $(document).ready(function(){ $('.widget').append("<a class='button' href='#'>...</div>"); $('a[href]').click(function(){...}); ... }); </script> Why isn't there a massive push to get XBL2.0 or .htc files or some kind of declarative behavior syntax implemented in a standard way across browsers? Is this recognized as a need by other web development professionals? Is there anything on the horizon for HTML5? (Caveats, disclaimers, etc: I realize that it's not a perfect world and that we're playing the hand we've been dealt. My point isn't to criticize the current way of doing things so much as to criticize the complacency that exists about the current way of doing things. Secondly, event delegation, especially at the root level, is a step closer to having a declarative behavior layer. It solves a subset of the problem, but it can't create UI elements, so the overall problem remains.)

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  • Is INotifyPropertyChanged only for the presentation layer?

    - by D.H.
    The INotifyPropertyChanged is obviously very useful in the view model for data binding to the view. Should I also use this interface in other parts of my application (e.g. in the business layer) when I want notifications of property changes, or I am better off using other notification mechanisms? I realize that there is nothing stopping me from using it, but are there any reasons that I shouldn't?

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  • Remove a layer from a ggplot2 chart

    - by Erik Shilts
    I'd like to remove a layer (in this case the results of geom_ribbon) from a ggplot2 created grid object. Is there a way I can remove it once it's already part of the object? library(ggplot2) dat <- data.frame(x=1:3, y=1:3, ymin=0:2, ymax=2:4) p <- ggplot(dat, aes(x=x, y=y)) + geom_ribbon(aes(ymin=ymin, ymax=ymax), alpha=0.3) + geom_line() # This has the geom_ribbon p # This overlays another ribbon on top p + geom_ribbon(aes(ymin=ymin, ymax=ymax, fill=NA))

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  • Accessing Erlang business layer via REST

    - by Polyn
    For a college project i'm thinking of implementing the business layer in Erlang and then accessing it via multiple front-ends using REST. I would like to avail of OTP features like distributed applications, etc. My question is how do I expose gen_server calls/casts to other applications? Obviously I could make RPC calls via language specific "bridges" like OTP.net or JInterface, but I want a consistent way to access it like REST.

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  • Data access layer using Linq to SQL

    - by Andrei Tanasescu
    I am building a c# - linq - sql server winforms/asp.net application, accessing a database. I would like my business logic layer to be easily testable, and that means not littering it with Linq database queries everywhere. What design patterns/ best practices are available for the following use cases - inserting/updating a new object - searching for an object - loading a bunch of related data into a sort of "presentation" object that could be displayed by various views ?

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  • Problem while inserting data from GUI layer to database

    - by Rahul
    Hi all, I am facing problem while i am inserting new record from GUI part to database table. I have created database table Patient with id, name, age etc....id is identity primary key. My problem is while i am inserting duplicate name in table the control should go to else part, and display the message like...This name is already exits, pls try with another name... but in my coding not getting..... Here is all the code...pls somebody point me out whats wrong or how do this??? GUILayer: protected void BtnSubmit_Click(object sender, EventArgs e) { if (!Page.IsValid) return; int intResult = 0; string name = TxtName.Text.Trim(); int age = Convert.ToInt32(TxtAge.Text); string gender; if (RadioButtonMale.Checked) { gender = RadioButtonMale.Text; } else { gender = RadioButtonFemale.Text; } string city = DropDownListCity.SelectedItem.Value; string typeofdisease = ""; foreach (ListItem li in CheckBoxListDisease.Items) { if (li.Selected) { typeofdisease += li.Value; } } typeofdisease = typeofdisease.TrimEnd(); PatientBAL PB = new PatientBAL(); PatientProperty obj = new PatientProperty(); obj.Name = name; obj.Age = age; obj.Gender = gender; obj.City = city; obj.TypeOFDisease = typeofdisease; try { intResult = PB.ADDPatient(obj); if (intResult > 0) { lblMessage.Text = "New record inserted successfully."; TxtName.Text = string.Empty; TxtAge.Text = string.Empty; RadioButtonMale.Enabled = false; RadioButtonFemale.Enabled = false; DropDownListCity.SelectedIndex = 0; CheckBoxListDisease.SelectedIndex = 0; } else { lblMessage.Text = "Name [<b>" + TxtName.Text + "</b>] alredy exists, try another name"; } } catch (Exception ex) { lblMessage.Text = ex.Message.ToString(); } finally { obj = null; PB = null; } } BAL layer: public class PatientBAL { public int ADDPatient(PatientProperty obj) { PatientDAL pdl = new PatientDAL(); try { return pdl.InsertData(obj); } catch { throw; } finally { pdl=null; } } } DAL layer: public class PatientDAL { public string ConString = ConfigurationManager.ConnectionStrings["ConString"].ConnectionString; public int InsertData(PatientProperty obj) { SqlConnection con = new SqlConnection(ConString); con.Open(); SqlCommand com = new SqlCommand("LoadData",con); com.CommandType = CommandType.StoredProcedure; try { com.Parameters.AddWithValue("@Name", obj.Name); com.Parameters.AddWithValue("@Age",obj.Age); com.Parameters.AddWithValue("@Gender",obj.Gender); com.Parameters.AddWithValue("@City", obj.City); com.Parameters.AddWithValue("@TypeOfDisease", obj.TypeOFDisease); return com.ExecuteNonQuery(); } catch { throw; } finally { com.Dispose(); con.Close(); } } } Property Class: public class PatientProperty { private string name; private int age; private string gender; private string city; private string typedisease; public string Name { get { return name; } set { name = value; } } public int Age { get { return age; } set { age = value; } } public string Gender { get { return gender; } set { gender = value; } } public string City { get { return city; } set { city = value; } } public string TypeOFDisease { get { return typedisease; } set { typedisease = value; } } } This is my stored Procedure: CREATE PROCEDURE LoadData ( @Name varchar(50), @Age int, @Gender char(10), @City char(10), @TypeofDisease varchar(50) ) as insert into Patient(Name, Age, Gender, City, TypeOfDisease)values(@Name,@Age, @Gender, @City, @TypeofDisease) GO

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  • How to use the unit of work and repository patterns in a service oriented enviroment

    - by A. Karimi
    I've created an application framework using the unit of work and repository patterns for it's data layer. Data consumer layers such as presentation depend on the data layer design. For example a CRUD abstract form has a dependency to a repository (IRepository). This architecture works like a charm in client/server environments (Ex. a WPF application and a SQL Server). But I'm looking for a good pattern to change or reuse this architecture for a service oriented environment. Of course I have some ideas: Idea 1: The "Adapter" design pattern Keep the current architecture and create a new unit of work and repository implementation which can work with a service instead of the ORM. Data layer consumers are loosely coupled to the data layer so it's possible but the problem is about the unit of work; I have to create a context which tracks the objects state at the client side and sends the changes to the server side on calling the "Commit" (Something that I think the RIA has done for Silverlight). Here the diagram: ----------- CLIENT----------- | ------------------ SERVER ---------------------- [ UI ] -> [ UoW/Repository ] ---> [ Web Services ] -> [ UoW/Repository ] -> [DB] Idea 2: Add another layer Add another layer (let say "local services" or "data provider"), then put it between the data layer (unit of work and repository) and the data consumer layers (like UI). Then I have to rewrite the consumer classes (CRUD and other classes which are dependent to IRepository) to depend on another interface. And the diagram: ----------------- CLIENT ------------------ | ------------------- SERVER --------------------- [ UI ] -> [ Local Services/Data Provider ] ---> [ Web Services ] -> [ UoW/Repository ] -> [DB] Please note that I have the local services layer on the current architecture but it doesn't expose the data layer functionality. In another word the UI layer can communicate with both of the data and local services layers whereas the local services layer also uses the data layer. | | | | | | | | ---> | Local Services | ---> | | | UI | | | | Data | | | | | | | ----------------------------> | |

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  • Parallelize code using CUDA [migrated]

    - by user878944
    If I have a code which takes struct variable as input and manipulate it's elements, how can I parallelize this using CUDA? void BackpropagateLayer(NET* Net, LAYER* Upper, LAYER* Lower) { INT i,j; REAL Out, Err; for (i=1; i<=Lower->Units; i++) { Out = Lower->Output[i]; Err = 0; for (j=1; j<=Upper->Units; j++) { Err += Upper->Weight[j][i] * Upper->Error[j]; } Lower->Error[i] = Net->Gain * Out * (1-Out) * Err; } } Where NET and LAYER are structs defined as: typedef struct { /* A LAYER OF A NET: */ INT Units; /* - number of units in this layer */ REAL* Output; /* - output of ith unit */ REAL* Error; /* - error term of ith unit */ REAL** Weight; /* - connection weights to ith unit */ REAL** WeightSave; /* - saved weights for stopped training */ REAL** dWeight; /* - last weight deltas for momentum */ } LAYER; typedef struct { /* A NET: */ LAYER** Layer; /* - layers of this net */ LAYER* InputLayer; /* - input layer */ LAYER* OutputLayer; /* - output layer */ REAL Alpha; /* - momentum factor */ REAL Eta; /* - learning rate */ REAL Gain; /* - gain of sigmoid function */ REAL Error; /* - total net error */ } NET; What I could think of is to first convert the 2d Weight into 1d. And then send it to kernel to take the product or just use the CUBLAS library. Any suggestions?

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  • Set caret position in contenteditable div layer in Chrome/webkit

    - by Alex
    Hello, I'm trying to set the caret position in a contenteditable div layer, and after a bit of searching the web and experimenting I got it to work in firefox using this: function set(element,position){ element.focus(); var range= window.getSelection().getRangeAt(0); range.setStart(element.firstChild,position); range.setEnd(element.firstChild,position); } [...] set(document.getElementById("test"),3); But in Chrome/webkit it selects all of the content in the div. Is this a bug with webkit or am I doing something wrong? Thank you in advance.

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