Search Results

Search found 14279 results on 572 pages for 'design choices'.

Page 152/572 | < Previous Page | 148 149 150 151 152 153 154 155 156 157 158 159  | Next Page >

• Two objects with dependencies for each other. Is that bad?

  - by Kasper Grubbe

  Hi SO. I am learning a lot about design patterns these days. And I want to ask you about a design question that I can't find an answer to. Currently I am building a little Chat-server using sockets, with multiple Clients. Currently I have three classes. Person-class which holds information like nick, age and a Room-object. Room-class which holds information like room-name, topic and a list of Persons currently in that room. Hotel-class which have a list of Persons and a list of Rooms on the server. I have made a diagram to illustrate it (Sorry for the big size!): http://i.imgur.com/Kpq6V.png I have a list of players on the server in the Hotel-class because it would be nice to keep track of how many there are online right now (Without having to iterate through all of the rooms). The persons live in the Hotel-class because I would like to be able to search for a specific Person without searching the rooms. Is this bad design? Is there another way of achieve it? Thanks.

  Read the article

• Game architecture: modeling different steps/types of UI

  - by Sander

  I have not done any large game development projects, only messed around with little toy projects. However, I never found an intuitive answer to a specific design question. Namely, how are different types/states of UI modeled in games? E.g. how is a menu represented? How is it different from a "game world" state (let's use an FPS as an example). How is an overlaid menu on top of a "game world" modeled? Let's imagine the main loop of a game. Where do the game states come into play? It it a simple case-by-case approach? if (menu.IsEnabled) menu.Process(elapsedTime); if (world.IsEnabled) world.Process(elapsedTime); if (menu.IsVisible) menu.Draw(); if (world.IsVisible) world.Draw(); Or are menu and world represented somewhere in a different logic layer and not represented at this level? (E.g. a menu is just another high-level entity like e.g. player input or enemy manager, equal to all others) foreach (var entity in game.HighLevelEntities) entity.Process(elapsedTime); foreach (var entity in game.HighLevelEntities) entity.Draw(elapsedTime); Are there well-known design patterns for this? Come to think of it, I don't know any game-specific design patterns - I assume there are others, as well? Please tell me about them.

  Read the article

• Where can a self-teacher learn general good programming habits and conventions?

  - by lucid

  A few mistakes and general childishness in early adulthood have left me in a situation where I work a menial job, with no possibility (in the near future) of attending school. I aspire to one day work in the programming field (gaming specifically), after proving myself on the indie end of things. I've gotten very confident in C++, java, and python, and I find I'm able to solve any problem I want either from previous experience, or from scouring the web for help. The solutions work, and with each attempt they become more readable, maintainable, and extensible. But this is because I'm learning from mistakes and bad programming and design habits I feel I might have avoided with actual schooling. General tips like: "if it's hard to read or getting long, or you're writing it twice, it should be in one or more functions." or "design all your classes before you start coding, so you don't have to rewrite classes later when you discover an unforeseen dependency" Is there a good book or website for learning general good programming practices and design habits? Also, naming and format conventions. I realize sometimes development houses have their own conventions, but things like "Classes in python usually have the first letter of each word capitalized". I'd like to be able to show some source code to a potential employer, and be prepared when for what's expected on a team. Is there some central database of naming and formatting conventions somewhere? Also, feel free to give any thoughts on whether or not the self-teach, garner some indie sales, use them as your resume' route is realistic

  Read the article

• How to properly implement the Strategy pattern in a web MVC framework?

  - by jboxer

  In my Django app, I have a model (lets call it Foo) with a field called "type". I'd like to use Foo.type to indicate what type the specific instance of Foo is (possible choices are "Number", "Date", "Single Line of Text", "Multiple Lines of Text", and a few others). There are two things I'd like the "type" field to end up affecting; the way a value is converted from its normal type to text (for example, in "Date", it may be str(the_date.isoformat())), and the way a value is converted from text to the specified type (in "Date", it may be datetime.date.fromtimestamp(the_text)). To me, this seems like the Strategy pattern (I may be completely wrong, and feel free to correct me if I am). My question is, what's the proper way to code this in a web MVC framework? In a client-side app, I'd create a Type class with abstract methods "serialize()" and "unserialize()", override those methods in subclasses of Type (such as NumberType and DateType), and dynamically set the "type" field of a newly-instantiated Foo to the appropriate Type subclass at runtime. In a web framework, it's not quite as straightforward for me. Right now, the way that makes the most sense is to define Foo.type as a Small Integer field and define a limited set of choices (0 = "Number", 1 = "Date", 2 = "Single Line of Text", etc.) in the code. Then, when a Foo object is instantiated, use a Factory method to look at the value of the instance's "type" field and plug in the correct Type subclass (as described in the paragraph above). Foo would also have serialize() and unserialize() methods, which would delegate directly to the plugged-in Type subclass. How does this design sound? I've never run into this issue before, so I'd really like to know if other people have, and how they've solved it.

  Read the article

• C++ Matrix class hierachy

  - by bpw1621

  Should a matrix software library have a root class (e.g., MatrixBase) from which more specialized (or more constrained) matrix classes (e.g., SparseMatrix, UpperTriangluarMatrix, etc.) derive? If so, should the derived classes be derived publicly/protectively/privately? If not, should they be composed with a implementation class encapsulating common functionality and be otherwise unrelated? Something else? I was having a conversation about this with a software developer colleague (I am not per se) who mentioned that it is a common programming design mistake to derive a more restricted class from a more general one (e.g., he used the example of how it was not a good idea to derive a Circle class from an Ellipse class as similar to the matrix design issue) even when it is true that a SparseMatrix "IS A" MatrixBase. The interface presented by both the base and derived classes should be the same for basic operations; for specialized operations, a derived class would have additional functionality that might not be possible to implement for an arbitrary MatrixBase object. For example, we can compute the cholesky decomposition only for a PositiveDefiniteMatrix class object; however, multiplication by a scalar should work the same way for both the base and derived classes. Also, even if the underlying data storage implementation differs the operator()(int,int) should work as expected for any type of matrix class. I have started looking at a few open-source matrix libraries and it appears like this is kind of a mixed bag (or maybe I'm looking at a mixed bag of libraries). I am planning on helping out with a refactoring of a math library where this has been a point of contention and I'd like to have opinions (that is unless there really is an objective right answer to this question) as to what design philosophy would be best and what are the pros and cons to any reasonable approach.

  Read the article

• What's the best way to store Logon User information for Web Application?

  - by Morgan Cheng

  I was once in a project of web application developed on ASP.NET. For each logon user, there is an object (let's call it UserSessionObject here) created and stored in RAM. For each HTTP request of given user, matching UserSessoinObject instance is used to visit user state information and connection to database. So, this UserSessionObject is pretty important. This design brings several problems found later: 1) Since this UserSessionObject is cached in ASP.NET memory space, we have to config load balancer to be sticky connection. That is, HTTP request in single session would always be sent to one web server behind. This limit scalability and maintainability. 2) This UserSessionObject is accessed in every HTTP request. To keep the consistency, there is a exclusive lock for the UserSessionObject. Only one HTTP request can be processed at any given time because it must to obtain the lock first. The performance and response time is affected. Now, I'm wondering whether there is better design to handle such logon user case. It seems Sharing-Nothing-Architecture helps. That means long user info is retrieved from database each time. I'm afraid that would hurt performance. Is there any design pattern for long user web app? Thanks.

  Read the article

• How to understand existing projects

  - by John

  Hi. I am a trainee developer and have been writing .NET applications for about a year now. Most of the work I have done has involved building new applications (mainly web apps) from scratch and I have been given more or less full control over the software design. This has been a great experience however, as a trainee developer my confidence about whether the approaches I have taken are the best is minimal. Ideally I would love to collaborate with more experienced developers (I find this the best was I learn) however in the company I work for developers tend to work in isolation (a great shame for me). Recently I decided that a good way to learn more about how experienced developers approach their design might be to explore some open source projects. I found myself a little overwhelmed by the projects I looked at. With my level of experience it was hard to understand the body of code I faced. My question is slight fuzzy one. How do developers approach the task of understanding a new medium to large scale project. I found myself pouring over lots of code and struggling to see the wood for the trees. At any one time I felt that I could understand a small portion of the system but not see how its all fits together. Do others get this same feeling? If so what approaches do you take to understanding the project? Do you have any other advice about how to learn design best practices? Any advice will be very much appreciated. Thank you.

  Read the article

• Application that depends heavily on stored procedures

  - by PieterG

  We currently have an application that depends largely on stored procedures. There is a heavy use of temp tables. It's an extremely large application. Facing this situation, I would like to use Entity Framework or Linq2Sql for a rewrite. I might consider using Fluent Hibernate or Subsonic, as i've used them quite extensively in the past. I've had problems with Linq2Sql generating the return types for the stored procedures because of the usage of the temp tables, and I think it's cumbersome to go and change all the stored procedures from temp tables to in-memory tables. Considering the 2 choices that I want to make, which one of the 2 is the best route to go and why? If my choices are extremely idiotic, please provide alternatives. Edit: The reason for the question and the change is that the data access layer is non-existent and was built 10 years ago. We currently still run into a lot of issues with it. I don't want to divulge too much, but if you saw it, your eyes would start bleeding :)

  Read the article

• Implementing search functionality with multiple optional parameters against database table.

  - by quarkX

  Hello, I would like to check if there is a preferred design pattern for implementing search functionality with multiple optional parameters against database table where the access to the database should be only via stored procedures. The targeted platform is .Net with SQL 2005, 2008 backend, but I think this is pretty generic problem. For example, we have customer table and we want to provide search functionality to the UI for different parameters, like customer Type, customer State, customer Zip, etc., and all of them are optional and can be selected in any combinations. In other words, the user can search by customerType only or by customerType, customerZIp or any other possible combinations. There are several available design approaches, but all of them have some disadvantages and I would like to ask if there is a preferred design among them or if there is another approach. Generate sql where clause sql statement dynamically in the business tier, based on the search request from the UI, and pass it to a stored procedure as parameter. Something like @Where = ‘where CustomerZip = 111111’ Inside the stored procedure generate dynamic sql statement and execute it with sp_executesql. Disadvantage: dynamic sql, sql injection Implement a stored procedure with multiple input parameters, representing the search fields from the UI, and use the following construction for selecting the records only for the requested fields in the where statement. WHERE (CustomerType = @CustomerType OR @CustomerType is null ) AND (CustomerZip = @CustomerZip OR @CustomerZip is null ) AND ………………………………………… Disadvantage: possible performance issue for the sql. 3.Implement separate stored procedure for each search parameter combinations. Disadvantage: The number of stored procedures will increase rapidly with the increase of the search parameters, repeated code.

  Read the article

• Eclipc java,writting a program [closed]

  - by ghassar

  I have an important exercise for that i found in the internet please i need help in using eclipc java thanks i have to design, implement, test and document a Java program (a set of classes) for one of the following problem specifications: Problem 1 – Jubilee Estate Agency Property Management System A local Estate Agent would like a prototype system to keep track of properties that are offered for sale. The Estate Agent sells domestic and commercial properties. You will need to define classes that represent the Estate Agency System. You should design your system and the classes that you will need before starting coding. Your system must have a graphical user interface and be designed and developed using the object-oriented principles of the MVC architecture design pattern i.e. the user interface class must be separate from the other classes. The initial basic requirements for the system are as follows: • Include a list of domestic properties for sale that include details of: address, description, selling price, and number of rooms • Include a list of commercial properties for sale that include details of: address, description, selling price, and area in square metres • Enable the properties that are for sale to be viewed on the screen • Allow the customer to select one or more properties to be placed on a ‘viewing list’ so that the properties can be visited in person • Display on the screen the viewing list that shows the details of the properties chosen • Provide a basic search facility to find properties that are for sale in a particular price band and display the results • Enable a property to be marked as sold

  Read the article

• design of orm tool

  - by ifree

  Hello , I want to design a orm tool for my daily work, but I'm always worry about the mapping of foreign key. Here's part of my code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data; namespace OrmTool { [AttributeUsage(AttributeTargets.Property)] public class ColumnAttribute:Attribute { public string Name { get; set; } public SqlDbType DataType { get; set; } public bool IsPk { get; set; } } [AttributeUsage(AttributeTargets.Class,AllowMultiple=false,Inherited=false)] public class TableAttribute:Attribute { public string TableName { get; set; } public string Description { get; set; } } [AttributeUsage(AttributeTargets.Property)] public class ReferencesAttribute : ColumnAttribut { public Type Host { get; set; } public string HostPkName{get;set;} } } I want to use Attribute to get the metadata of Entity ,then mapping them,but i think it's really hard to get it done; public class DbUtility { private static readonly string CONNSTR = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString; private static readonly Type TableType = typeof(TableAttribute); private static readonly Type ColumnType = typeof(ColumnAttribute); private static readonly Type ReferenceType = typeof(ReferencesAttribute); private static IList<TEntity> EntityListGenerator<TEntity>(string tableName,PropertyInfo[] props,params SqlParameter[] paras) { return null; } private static IList<TEntity> ResultList() { return null; } private static SqlCommand PrepareCommand(string sql,SqlConnection conn,params SqlParameter[] paras) { SqlCommand cmd = new SqlCommand(); cmd.CommandText = sql; cmd.Connection = conn; if (paras != null) cmd.Parameters.AddRange(paras); conn.Open(); return cmd; } } I don't know how to do the next step, if every Entity has it's own foreign key,how do I get the return result ? If the Entity like this: [Table(Name="ArtBook")] public class ArtBook{ [column(Name="id",IsPk=true,DataType=SqlDbType.Int)] public int Id{get;set;} [References(Name="ISBNId",DataType=SqlDataType.Int,Host=typeof(ISBN),HostPkName="Id")] public ISBN BookISBN{get;set;} public .....more properties. } public class ISBN{ public int Id{get;set;} public bool IsNative{get;set;} } If I read all ArtBooks from database and when I get a ReferencesAttribute how do I set the value of BookISBN?

  Read the article

• Sockets server design advice

  - by Rob

  We are writing a socket server in c# and need some advice on the design. Background: Clients (from mobile devices) connect to our server app and we leave their socket open so we can send data back down to them whenever we need to. The amount of data varies but we generally send/receive data from each client every few seconds, so it's quite intensive. The amount of simultaneous connections can range from 50-500 (and more in the future). We have already written a server app using async sockets and it works, however we've come across some stumbling blocks and we need to make sure that what we're doing is correct. We have a collection which holds our client states (we have no socket/connection pool at the moment, should we?). Each time a client connects we create a socket and then wait for them to send us some data and in receiveCallBack we add their clientstate object to our connections dictionary (once we have verified who they are). When a client object then signs off we shutdown their socket and then close it as well as remove them from our collection of clients dictionary. Presumably everything happens in the right order, everything works as expected. However, almost everyday it stops accepting connections, or so we think, either that or it connects but doesn't actually do anything past that and we can't work out why it's just stopping. There are few things that we'r'e unsure about 1) Should we be creating some kind of connection pool as opposed to just a dictionary of client sockets 2) What happens to the sockets that connect but then don't get added to our dictionary, they just linger around in memory doing nothing, should we create ANOTHER dictionary that holds the sockets as soon as they are created? 3) What's the best way of finding if clients are no longer connected? We've read some many methods but we're not sure of the best one to use, send data or read data, if so how? 4) If we loop through the connections dictonary to check for disposed clients, should we be locking the dictionary, if so how does this affect other clients objects trying to use it at the same time, will it throw an error or just wait? 5) We often get disposedSocketException within ReceiveCallBack method at random times, does this mean we are safe to remove that socket from the collection? We can't seem to find any production type examples which show any of this working. Any advice would be greatly received

  Read the article

• Design-time failure: WPF, Usercontrols and Namespaces

  - by Simon Woods

  Hi I have a very simple WPF project comprising a Window and Usercontrol. I'm very much in a learning phase. It works fine when I run it. However, I am unable to see the form in design time. The problem, I believe is something to do with namespaces, but I don't understand where. It may well be a simple error Main Window XML <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:views="clr-namespace:UserLogin" x:Class="UserLogin.MainView" x:Name="MainViewWindow" mc:Ignorable="d" Title="Login" Height="141" Width="347" > <Grid> <views:LoginView /> </Grid> </Window> Main Window CodeBehind Imports Microsoft.VisualBasic Imports System Imports System.Windows Imports UserLogin Namespace UserLogin Partial Public Class MainView Inherits System.Windows.Window Public Sub New() InitializeComponent() End Sub End Class End Namespace Usercontrol XAML <UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" x:Class="UserLogin.LoginView" x:Name="LoginViewControl" mc:Ignorable="d" d:DesignHeight="96" d:DesignWidth="298"> <Grid Height="96" Width="298"> <Button Command="{Binding OKCommand}" Height="21" Margin="0,0,90,16" Name="btnOK" VerticalAlignment="Bottom" HorizontalAlignment="Right" Width="76">OK</Button> <Button Command="{Binding CancelCommand}" Height="21" HorizontalAlignment="Right" Margin="0,0,9,16" Name="btnCancel" VerticalAlignment="Bottom" Width="75">Cancel</Button> <Label Height="23" HorizontalAlignment="Left" Margin="10,5,0,0" Name="Label1" VerticalAlignment="Top" Width="85">Name:</Label> <Label HorizontalAlignment="Left" Margin="10,32,0,0" Name="Label2" Width="85" Height="29" VerticalAlignment="Top">Password:</Label> <TextBox Margin="0,31,6,0" Name="txtPassword" Height="22" VerticalAlignment="Top" HorizontalAlignment="Right" Width="182" /> <ComboBox Height="22" Margin="110,6,6,0" Name="cboNames" VerticalAlignment="Top" /> </Grid> </UserControl> Usercontrol CodeBehind Imports Microsoft.VisualBasic Imports System Imports UserLogin Namespace UserLogin Partial Public Class LoginView Inherits System.Windows.Controls.UserControl Public Sub New() InitializeComponent() End Sub End Class End Namespace I think I'm missing something this namespace xmlns:views="clr-namespace:UserLogin" since intellisense doesn't give me the usercontrol declared within it in the XAML designer but rather reports the error "Unable to load the metadata for the assembly ... etc etc" Thx for any suggestions Simon

  Read the article

• Linked List Design

  - by Jim Scott

  The other day in a local .NET group I attend the following question came up: "Is it a valid interview question to ask about Linked Lists when hiring someone for a .NET development position?" Not having a computer sciense degree and being a self taught developer my response was that I did not feel it was appropriate as I in 5 years of developer with .NET had never been exposed to linked lists and did not hear any compeling reason for a use for one. However the person commented that it is a very common interview question so I decided when I left that I would do some reasearch on linked lists and see what I might be missing. I have read a number of posts on stack overflow and various google searches and decided the best way to learn about them was to write my own .NET classes to see how they worked from the inside out. Here is my class structure Single Linked List Constructor public SingleLinkedList(object value) Public Properties public bool IsTail public bool IsHead public object Value public int Index public int Count private fields not exposed to a property private SingleNode firstNode; private SingleNode lastNode; private SingleNode currentNode; Methods public void MoveToFirst() public void MoveToLast() public void Next() public void MoveTo(int index) public void Add(object value) public void InsertAt(int index, object value) public void Remove(object value) public void RemoveAt(int index) Questions I have: What are typical methods you would expect in a linked list? What is typical behaviour when adding new records? For example if I have 4 nodes and I am currently positioned in the second node and perform Add() should it be added after or before the current node? Or should it be added to the end of the list? Some of the designs I have seen explaining things seem to expose outside of the LinkedList class the Node object. In my design you simply add, get, remove values and know nothing about any node object. Should the Head and Tail be placeholder objects that are only used to define the head/tail of the list? I require my Linked List be instantiated with a value which creates the first node of the list which is essentially the head and tail of the list. Would you change that ? What should the rules be when it comes to removing nodes. Should someone be able to remove all nodes? Here is my Double Linked List Constructor public DoubleLinkedList(object value) Properties public bool IsHead public bool IsTail public object Value public int Index public int Count Private fields not exposed via property private DoubleNode currentNode; Methods public void AddFirst(object value) public void AddLast(object value) public void AddBefore(object existingValue, object value) public void AddAfter(object existingValue, object value) public void Add(int index, object value) public void Add(object value) public void Remove(int index) public void Next() public void Previous() public void MoveTo(int index)

  Read the article

• How to design this ?

  - by Akku

  how can i make this entire process as 1 single event??? http://code.google.com/apis/visualization/documentation/dev/dsl_get_started.html and draw the chart on single click? I am new to servlets please guide me When a user clicks the "go " button with some input. The data goes to the servlet say "Test3". The servlet processes the data by the user and generates/feeds the data table dynamically Then I call the html page to draw the chart as shown in the tutorial link above. The problem is when I call the servlet it gives me a long json string in the browser as given in the tutorials "google.visualization.Query.setResponse({version:'0.6',status:'ok',sig:'1333639331',table:{cols:[{............................" Then when i manually call the html page to draw the chart i am see the chart. But when I call html page directly using the request dispatcher via the servlet I dont get the result. This is my code and o/p...... I need sugession as to how should be my approach to call the chart public class Test3 extends HttpServlet implements DataTableGenerator { protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { DataSourceHelper.executeDataSourceServletFlow(request, response, this , isRestrictedAccessMode() ); RequestDispatcher rd; rd = request.getRequestDispatcher("new.html");// it call's the html page which draws the chart as per the data added by the servlet..... rd.include(request, response);//forward(request, response); @Override public Capabilities getCapabilities() { return Capabilities.NONE; } protected boolean isRestrictedAccessMode() { return false; } @Override public DataTable generateDataTable(Query query, HttpServletRequest request) { // Create a data table. DataTable data = new DataTable(); ArrayList<ColumnDescription> cd = new ArrayList<ColumnDescription>(); cd.add(new ColumnDescription("name", ValueType.TEXT, "Animal name")); cd.add......... I get the following result along with unprocessed html page google.visualization.Query.setResponse({version:'0.6',statu..... <html> <head> <title>Getting Started Example</title> .... Entire html page as it is on the Browser. What I need is when a user clicks the go button the servlet should process the data and call the html page to draw the chart....Without the json string appearing on the browser.(all in one user click) What should be my approach or how should i design this.... there are no error in the code. since when i run the servlet i get the json string on the browser and then when i run the html page manually i get the chart drawn. So how can I do (servlet processing + html page drawing chart as final result) at one go without the long json string appearing on the browser. There is no problem with the html code....

  Read the article

• Advice for Architecture Design Logic for software application

  - by Prasad

  Hi, I have a framework of basic to complex set of objects/classes (C++) running into around 500. With some rules and regulations - all these objects can communicate with each other and hence can cover most of the common queries in the domain. My Dream: I want to provide these objects as icons/glyphs (as I learnt recently) on a workspace. All these objects can be dragged/dropped into the workspace. They have to communicate only through their methods(interface) and in addition to few iterative and conditional statements. All these objects are arranged finally to execute a protocol/workflow/dataflow/process. After drawing the flow, the user clicks the Execute/run button. All the user interaction should be multi-touch enabled. The best way to show my dream is : Jeff Han's Multitouch Video. consider Jeff is playing with my objects instead of the google maps. :-) it should be like playing a jigsaw puzzle. Objective: how can I achieve the following while working on this final product: a) the development should be flexible to enable provision for web services b) the development should enable easy web application development c) The development should enable client-server architecture - d) further it should also enable mouse based drag/drop desktop application like Adobe programs etc. I mean to say: I want to economize on investments. Now I list my efforts till now in design : a) Created an Editor (VB) where the user writes (manually) the object / class code b) On Run/Execute, the code is copied into a main() function and passed to interpreter. c) Catch the output and show it in the console. The interpreter can be separated to become a server and the Editor can become the client. This needs lot of standard client-server architecture work. But some how I am not comfortable in the tightness of this system. Without interpreter is there much faster and better embeddable solution to this? - other than writing a special compiler for these objects. Recently learned about AXIS-C++ can help me - looks like - a friend suggested. Is that the way to go ? Here are my questions: (pl. consider me a self taught programmer and NOT my domain) a) From the stage of C++ objects to multi-touch product, how can I make sure I will develop the parallel product/service models as well.? What should be architecture aspects I should consider ? b) What technologies are best suited for this? c) If I am thinking of moving to Cloud Computing, how difficult/ how redundant / how unnecessary my efforts will be ? d) How much time in months would it take to get the first beta ? I take the liberty to ask if any of the experts here are interested in this project, please email me: [email protected] Thank you for any help. Looking forward.

  Read the article

• Design time error - multiple controls with the same Id

  - by ilivewithian

  I'm using VS 2008, I have a very simple page that has a bunch of uniquely named controls. When I try to view it in design mode I get the following error: Error Rendering Control - Label12 An unhanded exception has occurred. Multiple controls with the same ID 'Label1' were found. FindControl requires that controls have unique IDs I've checked the HTML and the designer file and I can only see one control called Label1. What might be causing this? Also, here is the aspx markup I'm having trouble with? <%@ Page Language="vb" AutoEventWireup="false" CodeBehind="CoachingAppearanceReport.aspx.vb" Inherits="AcademyPro.CoachingAppearanceReport" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title></title> </head> <body> <form id="form1" runat="server"> <asp:UpdatePanel ID="UpdatePanel1" runat="server"> <ContentTemplate> <div id="appearanceDetail" class="Left CriteriaContainer"> <asp:Label ID="Label1" runat="server" Text="Appearance Type" AssociatedControlID="ddlAppearanceType" /> <asp:DropDownList ID="ddlAppearanceType" runat="server" CssClass="AppType" OnDataBound="ddlAppearanceType_DataBound" DataSourceID="odsAppearanceType" DataTextField="AppearanceType" DataValueField="AppearanceTypeCode"> </asp:DropDownList> <asp:RequiredFieldValidator ID="rfvAppearanceType" runat="server" ControlToValidate="ddlAppearanceType" InitialValue="" Text="*" ErrorMessage="The appearance type must be selected" /> <asp:Label ID="lblAppearanceType" runat="server" /> <br /> <div class="SubSettings"> <asp:Label ID="Label12" runat="server" Text="Subbed for" AssociatedControlID="ddlSubbedFor" /> <asp:DropDownList ID="ddlSubbedFor" runat="server" OnDataBound="ddlSubbedFor_DataBound" DataSourceID="odsPlayersInAgeGroup" DataTextField="PlayerName" DataValueField="PlayerID"> </asp:DropDownList> <asp:Label ID="lblSubbedFor" runat="server" /> <br /> <asp:Label ID="Label13" runat="server" Text="Mins" AssociatedControlID="txtSubMins" /> <asp:TextBox ID="txtSubMins" runat="server" MaxLength="3" CssClass="TinyWidth" /> <asp:Label ID="lblSubMins" runat="server" /> </div> </div> </ContentTemplate> </asp:UpdatePanel> </form> </body> </html>

  Read the article

• Parallel Task Library WaitAny Design

  - by colithium

  I've just begun to explore the PTL and have a design question. My Scenario: I have a list of URLs that each refer to an image. I want each image to be downloaded in parallel. As soon as at least one image is downloaded, I want to execute a method that does something with the downloaded image. That method should NOT be parallelized -- it should be serial. I think the following will work but I'm not sure if this is the right way to do it. Because I have separate classes for collecting the images and for doing "something" with the collected images, I end up passing around an array of Tasks which seems wrong since it exposes the inner workings of how images are retrieved. But I don't know a way around it. In reality there is more to both of these methods but that's not important for this. Just know that they really shouldn't be lumped into one large method that both retrieves and does something with the image. Task<Image>[] downloadTasks = collector.RetrieveImages(listOfURLs); for (int i = 0; i < listOfURLs.Count; i++) { //Wait for any of the remaining downloads to complete int completedIndex = Task<Image>.WaitAny(downloadTasks); Image completedImage = downloadTasks[completedIndex].Result; //Now do something with the image (this "something" must happen serially) } /////////////////////////////////////////////////// public Task<Image>[] RetrieveImages(List<string> urls) { Task<Image>[] tasks = new Task<Image>[urls.Count]; int index = 0; foreach (string url in urls) { string lambdaVar = url; //Required... Bleh tasks[index] = Task<Image>.Factory.StartNew(() => { using (WebClient client = new WebClient()) { //TODO: Replace with live image locations string fileName = String.Format("{0}.png", i); client.DownloadFile(lambdaVar, Path.Combine(Application.StartupPath, fileName)); } return Image.FromFile(Path.Combine(Application.StartupPath, fileName)); }, TaskCreationOptions.LongRunning | TaskCreationOptions.AttachedToParent); index++; } return tasks; }

  Read the article

• Database design advice needed.

  - by user346271

  Hi all, I'm a lone developer for a telecoms company, and am after some database design advice from anyone with a bit of time to answer. I am inserting into one table ~2 million rows each day, these tables then get archived and compressed on a monthly basis. Each monthly table contains ~15,000,000 rows. Although this is increasing month on month. For every insert I do above I am combining the data from rows which belong together and creating another "correlated" table. This table is currently not being archived, as I need to make sure I never miss an update to the correlated table. (Hope that makes sense) Although in general this information should remain fairly static after a couple of days of processing. All of the above is working perfectly. However my company now wishes to perform some stats against this data, and these tables are getting too large to provide the results in what would be deemed a reasonable time. Even with the appropriate indexes set. So I guess after all the above my question is quite simple. Should I write a script which groups the data from my correlated table into smaller tables. Or should I store the queries result sets in something like memcache? I'm already using mysqls cache, but due to having limited control over how long the data is stored for, it's not working ideally. The main advantages I can see of using something like memcache: No blocking on my correlated table after the query has been cashed. Greater flexibility of sharing the collected data between the backend collector and front end processor. (i.e custom reports could be written in the backend and the results of these stored in the cache under a key which then gets shared with anyone who would want to see the data of this report) Redundancy and scalability if we start sharing this data with a large amount of customers. The main disadvantages I can see of using something like memcache: Data is not persistent if machine is rebooted / cache is flushed. The main advantages of using MySql Persistent data. Less code changes (although adding something like memcache is trivial anyway) The main disadvantages of using MySql Have to define table templates every time I want to store provide a new set of grouped data. Have to write a program which loops through the correlated data and fills these new tables. Potentially will still grow slower as the data continues to be filled. Apologies for quite a long question. It's helped me to write down these thoughts here anyway, and any advice/help/experience with dealing with this sort of problem would be greatly appreciated. Many thanks. Alan

  Read the article

• Architectural Design for a Data-Driven Silverlight WP7 app

  - by Rosarch

  I have a Silverlight Windows Phone 7 app that pulls data from a public API. I find myself doing much of the same thing over and over again: In the UI, set a loading message or loading progress bar in place of where the content is Get the content, which may be already in memory, cached in isolated file storage, or require an HTTP request If the content can not be acquired (no network connection, etc), display an error message If the content is acquired, display it in the UI Keep the content in main memory for subsequent queries The content that is displayed to the user can be taken directly from a data source, such as an ObservableCollection, or it may be a query on a data source. I would like to factor out this repetitive process into a framework where ideally only the following needs to be specified: Where to display the content in the UI The UI elements to show while loading, on failure, and on success The URI of the HTTP request How to parse the HTTP response into the data structure that will kept in memory The location of the file in isolated storage, if it exists How to parse the file contents into the data structure that will be kept in memory It may sound like a lot, but two strings, three FrameworkElements, and two methods is less than the overhead that I currently have. Also, this needs to work for however the data is maintained in memory, and needs to work for direct collections and queries on those collections. My questions are: Has something like this already been implemented? Are my thoughts about the topic above fundamentally wrong in some way? Here is a design I'm thinking of: There are two components, a View and a Model. The View is given the FrameworkElements for loading, failure, and success. It is also given a reference to the corresponding Model. The View is a UserControl that is placed somewhere in the UI. The Model a class that is given the URI for the data, a method of how to parse the data, and optionally a filename and how to parse the file. It is responsible for retrieving the data and notifying the View whenever the current status (loading/fail/success) changes. If the data downloaded from the network is different from the cache, the network data takes precedence. When the app closes or is tombstoned, the model writes the data to the cache. How does that sound?

  Read the article

• FluentNHibernate Unit Of Work / Repository Design Pattern Questions

  - by Echiban

  Hi all, I think I am at a impasse here. I have an application I built from scratch using FluentNHibernate (ORM) / SQLite (file db). I have decided to implement the Unit of Work and Repository Design pattern. I am at a point where I need to think about the end game, which will start as a WPF windows app (using MVVM) and eventually implement web services / ASP.Net as UI. Now I already created domain objects (entities) for ORM. And now I don't know how should I use it outside of ORM. Questions about it include: Should I use ORM entity objects directly as models in MVVM? If yes, do I put business logic (such as certain values must be positive and be greater than another Property) in those entity objects? It is certainly the simpler approach, and one I am leaning right now. However, will there be gotchas that would trash this plan? If the answer above is no, do I then create a new set of classes to implement business logic and use those as Models in MVVM? How would I deal with the transition between model objects and entity objects? I guess a type converter implementation would work well here. Now I followed this well written article to implement the Unit Of Work pattern. However, due to the fact that I am using FluentNHibernate instead of NHibernate, I had to bastardize the implementation of UnitOfWorkFactory. Here's my implementation: using System; using FluentNHibernate.Cfg; using FluentNHibernate.Cfg.Db; using NHibernate; using NHibernate.Cfg; using NHibernate.Tool.hbm2ddl; namespace ELau.BlindsManagement.Business { public class UnitOfWorkFactory : IUnitOfWorkFactory { private static readonly string DbFilename; private static Configuration _configuration; private static ISession _currentSession; private ISessionFactory _sessionFactory; static UnitOfWorkFactory() { // arbitrary default filename DbFilename = "defaultBlindsDb.db3"; } internal UnitOfWorkFactory() { } #region IUnitOfWorkFactory Members public ISession CurrentSession { get { if (_currentSession == null) { throw new InvalidOperationException(ExceptionStringTable.Generic_NotInUnitOfWork); } return _currentSession; } set { _currentSession = value; } } public ISessionFactory SessionFactory { get { if (_sessionFactory == null) { _sessionFactory = BuildSessionFactory(); } return _sessionFactory; } } public Configuration Configuration { get { if (_configuration == null) { Fluently.Configure().ExposeConfiguration(c => _configuration = c); } return _configuration; } } public IUnitOfWork Create() { ISession session = CreateSession(); session.FlushMode = FlushMode.Commit; _currentSession = session; return new UnitOfWorkImplementor(this, session); } public void DisposeUnitOfWork(UnitOfWorkImplementor adapter) { CurrentSession = null; UnitOfWork.DisposeUnitOfWork(adapter); } #endregion public ISession CreateSession() { return SessionFactory.OpenSession(); } public IStatelessSession CreateStatelessSession() { return SessionFactory.OpenStatelessSession(); } private static ISessionFactory BuildSessionFactory() { ISessionFactory result = Fluently.Configure() .Database( SQLiteConfiguration.Standard .UsingFile(DbFilename) ) .Mappings(m => m.FluentMappings.AddFromAssemblyOf<UnitOfWorkFactory>()) .ExposeConfiguration(BuildSchema) .BuildSessionFactory(); return result; } private static void BuildSchema(Configuration config) { // this NHibernate tool takes a configuration (with mapping info in) // and exports a database schema from it _configuration = config; new SchemaExport(_configuration).Create(false, true); } } } I know that this implementation is flawed because a few tests pass when run individually, but when all tests are run, it would fail for some unknown reason. Whoever wants to help me out with this one, given its complexity, please contact me by private message. I am willing to send some $$$ by Paypal to someone who can address the issue and provide solid explanation. I am new to ORM, so any assistance is appreciated.

  Read the article

• Core Data Model Design Question - Changing "Live" Objects also Changes Saved Objects

  - by mwt

  I'm working on my first Core Data project (on iPhone) and am really liking it. Core Data is cool stuff. I am, however, running into a design difficulty that I'm not sure how to solve, although I imagine it's a fairly common situation. It concerns the data model. For the sake of clarity, I'll use an imaginary football game app as an example to illustrate my question. Say that there are NSMO's called Downs and Plays. Plays function like templates to be used by Downs. The user creates Plays (for example, Bootleg, Button Hook, Slant Route, Sweep, etc.) and fills in the various properties. Plays have a to-many relationship with Downs. For each Down, the user decides which Play to use. When the Down is executed, it uses the Play as its template. After each down is run, it is stored in history. The program remembers all the Downs ever played. So far, so good. This is all working fine. The question I have concerns what happens when the user wants to change the details of a Play. Let's say it originally involved a pass to the left, but the user now wants it to be a pass to the right. Making that change, however, not only affects all the future executions of that Play, but also changes the details of the Plays stored in history. The record of Downs gets "polluted," in effect, because the Play template has been changed. I have been rolling around several possible fixes to this situation, but I imagine the geniuses of SO know much more about how to handle this than I do. Still, the potential fixes I've come up with are: 1) "Versioning" of Plays. Each change to a Play template actually creates a new, separate Play object with the same name (as far as the user can tell). Underneath the hood, however, it is actually a different Play. This would work, AFAICT, but seems like it could potentially lead to a wild proliferation of Play objects, esp. if the user keeps switching back and forth between several versions of the same Play (creating object after object each time the user switches). Yes, the app could check for pre-existing, identical Plays, but... it just seems like a mess. 2) Have Downs, upon saving, record the details of the Play they used, but not as a Play object. This just seems ridiculous, given that the Play object is there to hold those just those details. 3) Recognize that Play objects are actually fulfilling 2 functions: one to be a template for a Down, and the other to record what template was used. These 2 functions have a different relationship with a Down. The first (template) has a to-many relationship. But the second (record) has a one-to-one relationship. This would mean creating a second object, something like "Play-Template" which would retain the to-many relationship with Downs. Play objects would get reconfigured to have a one-to-one relationship with Downs. A Down would use a Play-Template object for execution, but use the new kind of Play object to store what template was used. It is this change from a to-many relationship to a one-to-one relationship that represents the crux of the problem. Even writing this question out has helped me get clearer. I think something like solution 3 is the answer. However if anyone has a better idea or even just a confirmation that I'm on the right track, that would be helpful. (Remember, I'm not really making a football game, it's just faster/easier to use a metaphor everyone understands.) Thanks.

  Read the article

• Object validator - is this good design?

  - by neo2862

  I'm working on a project where the API methods I write have to return different "views" of domain objects, like this: namespace View.Product { public class SearchResult : View { public string Name { get; set; } public decimal Price { get; set; } } public class Profile : View { public string Name { get; set; } public decimal Price { get; set; } [UseValidationRuleset("FreeText")] public string Description { get; set; } [SuppressValidation] public string Comment { get; set; } } } These are also the arguments of setter methods in the API which have to be validated before storing them in the DB. I wrote an object validator that lets the user define validation rulesets in an XML file and checks if an object conforms to those rules: [Validatable] public class View { [SuppressValidation] public ValidationError[] ValidationErrors { get { return Validator.Validate(this); } } } public static class Validator { private static Dictionary<string, Ruleset> Rulesets; static Validator() { // read rulesets from xml } public static ValidationError[] Validate(object obj) { // check if obj is decorated with ValidatableAttribute // if not, return an empty array (successful validation) // iterate over the properties of obj // - if the property is decorated with SuppressValidationAttribute, // continue // - if it is decorated with UseValidationRulesetAttribute, // use the ruleset specified to call // Validate(object value, string rulesetName, string FieldName) // - otherwise, get the name of the property using reflection and // use that as the ruleset name } private static List<ValidationError> Validate(object obj, string fieldName, string rulesetName) { // check if the ruleset exists, if not, throw exception // call the ruleset's Validate method and return the results } } public class Ruleset { public Type Type { get; set; } public Rule[] Rules { get; set; } public List<ValidationError> Validate(object property, string propertyName) { // check if property is of type Type // if not, throw exception // iterate over the Rules and call their Validate methods // return a list of their return values } } public abstract class Rule { public Type Type { get; protected set; } public abstract ValidationError Validate(object value, string propertyName); } public class StringRegexRule : Rule { public string Regex { get; set; } public StringRegexRule() { Type = typeof(string); } public override ValidationError Validate(object value, string propertyName) { // see if Regex matches value and return // null or a ValidationError } } Phew... Thanks for reading all of this. I've already implemented it and it works nicely, and I'm planning to extend it to validate the contents of IEnumerable fields and other fields that are Validatable. What I'm particularly concerned about is that if no ruleset is specified, the validator tries to use the name of the property as the ruleset name. (If you don't want that behavior, you can use [SuppressValidation].) This makes the code much less cluttered (no need to use [UseValidationRuleset("something")] on every single property) but it somehow doesn't feel right. I can't decide if it's awful or awesome. What do you think? Any suggestions on the other parts of this design are welcome too. I'm not very experienced and I'm grateful for any help. Also, is "Validatable" a good name? To me, it sounds pretty weird but I'm not a native English speaker.

  Read the article

• Designing a software based load balancer

  - by Kishore pandey

  Hello to all Server fault users, I am new to this website but have constantly been using the mother website, stackover flow. Well to begin with, i would like to design a load balancer for the organization i am working for. As i am very new to this whole, idea about load balancing and networks. I am finding it very difficult to start my project. I did a lot of research on already existing load balancer and found some(HAPROXY,NGINX) that could solve my problems, but the point is, I am still in a dilemma if they could answer the following requirements of mine: The client and server in my architecture are distributed. The load balancer should take care of the firewall. LB server should balance the load among all servers present in WWW cloud. The LB server should have some sort of configuration file, with the help of which it is possible to configure the servers. Heart beat: With the help of which it would be possible to check if any server is down, if any server is down the request should be passed to some other server. Various load balancing algorithms of the incoming requests. Easy error handling. It should be fairly possible to prioritize the incoming requests. Is there any already available load balncer solution on the market that could satisfy these requirements? If not is there any base code available with the help of which i could develop my own load balncer. If not where should i start from scratch? I am practically new to everything. Any help from a load balancer expert is very much appreciated. Thanx a ton in advance. Cheers and regards. Kishore

  Read the article

• .NET interview, code structure and the design

  - by j_lewis

  I have been given the below .NET question in an interview. I don’t know why I got low marks. Unfortunately I did not get a feedback. Question: The file hockey.csv contains the results from the Hockey Premier League. The columns ‘For’ and ‘Against’ contain the total number of goals scored for and against each team in that season (so Alabama scored 79 goals against opponents, and had 36 goals scored against them). Write a program to print the name of the team with the smallest difference in ‘for’ and ‘against’ goals. the structure of the hockey.csv looks like this (it is a valid csv file, but I just copied the values here to get an idea) Team - For - Against Alabama 79 36 Washinton 67 30 Indiana 87 45 Newcastle 74 52 Florida 53 37 New York 46 47 Sunderland 29 51 Lova 41 64 Nevada 33 63 Boston 30 64 Nevada 33 63 Boston 30 64 Solution: class Program { static void Main(string[] args) { string path = @"C:\Users\<valid csv path>"; var resultEvaluator = new ResultEvaluator(string.Format(@"{0}\{1}",path, "hockey.csv")); var team = resultEvaluator.GetTeamSmallestDifferenceForAgainst(); Console.WriteLine( string.Format("Smallest difference in ‘For’ and ‘Against’ goals > TEAM: {0}, GOALS DIF: {1}", team.Name, team.Difference )); Console.ReadLine(); } } public interface IResultEvaluator { Team GetTeamSmallestDifferenceForAgainst(); } public class ResultEvaluator : IResultEvaluator { private static DataTable leagueDataTable; private readonly string filePath; private readonly ICsvExtractor csvExtractor; public ResultEvaluator(string filePath){ this.filePath = filePath; csvExtractor = new CsvExtractor(); } private DataTable LeagueDataTable{ get { if (leagueDataTable == null) { leagueDataTable = csvExtractor.GetDataTable(filePath); } return leagueDataTable; } } public Team GetTeamSmallestDifferenceForAgainst() { var teams = GetTeams(); var lowestTeam = teams.OrderBy(p => p.Difference).First(); return lowestTeam; } private IEnumerable<Team> GetTeams() { IList<Team> list = new List<Team>(); foreach (DataRow row in LeagueDataTable.Rows) { var name = row["Team"].ToString(); var @for = int.Parse(row["For"].ToString()); var against = int.Parse(row["Against"].ToString()); var team = new Team(name, against, @for); list.Add(team); } return list; } } public interface ICsvExtractor { DataTable GetDataTable(string csvFilePath); } public class CsvExtractor : ICsvExtractor { public DataTable GetDataTable(string csvFilePath) { var lines = File.ReadAllLines(csvFilePath); string[] fields; fields = lines[0].Split(new[] { ',' }); int columns = fields.GetLength(0); var dt = new DataTable(); //always assume 1st row is the column name. for (int i = 0; i < columns; i++) { dt.Columns.Add(fields[i].ToLower(), typeof(string)); } DataRow row; for (int i = 1; i < lines.GetLength(0); i++) { fields = lines[i].Split(new char[] { ',' }); row = dt.NewRow(); for (int f = 0; f < columns; f++) row[f] = fields[f]; dt.Rows.Add(row); } return dt; } } public class Team { public Team(string name, int against, int @for) { Name = name; Against = against; For = @for; } public string Name { get; private set; } public int Against { get; private set; } public int For { get; private set; } public int Difference { get { return (For - Against); } } } Output: Smallest difference in for' andagainst' goals TEAM: Boston, GOALS DIF: -34 Can someone please review my code and see anything obviously wrong here? They were only interested in the structure/design of the code and whether the program produces the correct result (i.e lowest difference). Much appreciated. "P.S - Please correct me if the ".net-interview" tag is not the right tag to use"

  Read the article

< Previous Page | 148 149 150 151 152 153 154 155 156 157 158 159  | Next Page >