Search Results

Search found 79791 results on 3192 pages for 'design problem'.

Page 197/3192 | < Previous Page | 193 194 195 196 197 198 199 200 201 202 203 204  | Next Page >

• 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

• Tips and Suggestions IP Address Re-Addressing?

  - by RSXAdmin

  Hello serverfault Universe, My ever evolving and expanding local area network is currently using a class-C address. My network consists of multiple subnets depending on site/location. 192.168.1.x is site HQ 192.168.5.x is secondary site 192.168.10.x is so on and so forth. Long story short - I have inherited this network design from the previous admin who has left the company which started off with a dozen people and now has just over 300 full time/part time employees. We do not yet have client VPN access; but we do have site to site VPN setup. My question is, in preparation for outside client access to my network via Cisco ASA, I would like to re-address the HQ site because I understand a 192.168.1.x or 192.168.0.x are not very good choices for a company subnet - it may conflict with a home user's LAN when connecting to my LAN, I believe? Through your experience, does anyone out there have any suggestions and tips on how I can proceed with re-addressing my subnets. If I designed this network I would have gone with a 10.0.0.0 (mask 255.255.255.0) so I am leaning towards changing it to fit. Thank you.

  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

• Android NDK r4 san-angeles problem

  - by Goz

  Hi All, I'm starting to learn the android NDK and I've instantly come up against a problem. I'e built the tool chain (which took a LOT longer than I was expecting!!) and I've compiled the C++ code with no problems and now I'm trying to build the java code. Instantly I come up against a problem. There is a file "main.xml" <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" > <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Hello World, DemoActivity" /> </LinearLayout> and I get the following errors: Description Resource Path Location Type error: Error: String types not allowed (at 'layout_height' with value 'match_parent'). main.xml /DemoActivity/res/layout line 2 Android AAPT Problem error: Error: String types not allowed (at 'layout_height' with value 'match_parent'). main.xml /DemoActivity/res/layout line 2 Android AAPT Problem error: Error: String types not allowed (at 'layout_width' with value 'match_parent'). main.xml /DemoActivity/res/layout line 2 Android AAPT Problem error: Error: String types not allowed (at 'layout_width' with value 'match_parent'). main.xml /DemoActivity/res/layout line 7 Android AAPT Problem error: Error: String types not allowed (at 'layout_width' with value 'match_parent'). main.xml /DemoActivity/res/layout line 7 Android AAPT Problem So I can see the problem lies in the fact that these "match_parent" strings are in there. Anyone know how to fix this?

  Read the article

• Problem with persisting interface collection at design time in winforms, .net

  - by Jules

  The easiest way to explain this problem is to show you some code: Public Interface IAmAnnoyed End Interface Public Class IAmAnnoyedCollection Inherits ObjectModel.Collection(Of IAmAnnoyed) End Class Public Class Anger Implements IAmAnnoyed End Class Public Class MyButton Inherits Button Private _Annoyance As IAmAnnoyedCollection <DesignerSerializationVisibility(DesignerSerializationVisibility.Content)> _ Public ReadOnly Property Annoyance() As IAmAnnoyedCollection Get Return _Annoyance End Get End Property Private _InternalAnger As Anger <DesignerSerializationVisibility(DesignerSerializationVisibility.Content)> _ Public ReadOnly Property InternalAnger() As Anger Get Return Me._InternalAnger End Get End Property Public Sub New() Me._Annoyance = New IAmAnnoyedCollection Me._InternalAnger = New Anger Me._Annoyance.Add(Me._InternalAnger) End Sub End Class And this is the code that the designer generates: Private Sub InitializeComponent() Dim Anger1 As Anger = New Anger Me.MyButton1 = New MyButton ' 'MyButton1 ' Me.MyButton1.Annoyance.Add(Anger1) // Should be: Me.MyButton1.Annoyance.Add(Me.MyButton1.InternalAnger) ' 'Form1 ' Me.Controls.Add(Me.MyButton1) End Sub I've added a comment to the above to show how the code should have been generated. Now, if I dispense with the interface and just have a collection of Anger, then it persists correctly. Any ideas?

  Read the article

• Problem with persisting inteface collection at design time in winforms, .net

  - by Jules

  The easiest way to explain this problem is to show you some code: Public Interface IAmAnnoyed End Interface Public Class IAmAnnoyedCollection Inherits ObjectModel.Collection(Of IAmAnnoyed) End Class Public Class Anger Implements IAmAnnoyed End Class Public Class MyButton Inherits Button Private _Annoyance As IAmAnnoyedCollection <DesignerSerializationVisibility(DesignerSerializationVisibility.Content)> _ Public ReadOnly Property Annoyance() As IAmAnnoyedCollection Get Return _Annoyance End Get End Property Private _InternalAnger As Anger <DesignerSerializationVisibility(DesignerSerializationVisibility.Content)> _ Public ReadOnly Property InternalAnger() As Anger Get Return Me._InternalAnger End Get End Property Public Sub New() Me._Annoyance = New IAmAnnoyedCollection Me._InternalAnger = New Anger Me._Annoyance.Add(Me._InternalAnger) End Sub End Class And this is the code that the designer generates: Private Sub InitializeComponent() Dim Anger1 As Anger = New Anger Me.MyButton1 = New MyButton ' 'MyButton1 ' Me.MyButton1.Annoyance.Add(Anger1) // Should be: Me.MyButton1.Annoyance.Add(Me.MyButton1.InternalAnger) ' 'Form1 ' Me.Controls.Add(Me.MyButton1) End Sub I've added a comment to the above to show how the code should have been generated. Now, if I dispense with the interface and just have a collection of Anger, then it persists correctly. Any ideas?

  Read the article

• Visual studio winform designer shows design errors as text rather than html

  - by Miki Watts

  All of the sudden, visual studio displays designer errors as plain html text, for example: <DIV id="div1" class="ErrorStyle" width="100%"><span style="font-weight: 600"><br>Object reference not set to an instance of an object. </span><br><a href="" instead of displaying the usual html formatted. I haven't been able to find anything similar to it on google. Before getting this problem, when I tried opening the winform designer, I would get the run/save/cancel dialog of internet explorer for a .tmp file, instead of the designer window. That went away when I found out that I had notepad assigned to the .tmp file type and removed that. Any ideas how to fix this?

  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

• SharePoint - Remote machine shows wrong design

  - by imsatasia

  Hi.! I am creating a SharePoint public website on SharePoint Server 2007. I've added my custom Master-page for Publishing site. When I see, Home page, on my local machine, in the content area of my page it shows me IMAGE on the right as I want to see. But, When I see that page on my remote machine It shows my IMAGE on the left, instead of right side. I'm using following layout: <div id="Content"> <div id="left"> </div> <div id="right"> **--->>>I've IMAGE over here..!!!!** </div> </div> Can Anyone help me how to resolve this problem. Thanks.

  Read the article

• Design RESTful service with multiple ids

  - by Dustin Digmann

  I am designing a RESTful service. It is to list a set of data. The main problem is that the set does not have a reasonable, single identifier. Nor can the specific set be easily calculated within the knowledge of the system. As a result, it does not seem possible to have a GET /items/{identifier} service. I do have the id of each element being requested. My main issue is that it does not seem RESTful to list the ids in the URI (eg GET items/{id1},{id2},...,{idn} ). Right? I could see DELETE having a similar use case - remove multiple items in one request cycle. How would such a use case be satisfied while staying within the REST realm? Is that possible?

  Read the article

• Fedora 13 post security update boot problem

  - by Alex

  Hello. About a month ago I installed a security update that had new Kernek 2.6.34.x from 2.6.33.x), this is when the problem occurred for the first time. After the install my computer would not boot at all, black screen without any visible hard drive activity (I gave it good 30 minutes on black screen, before took actions)... I poped in installation DVD and went in rescue mode to change back the boot option to old kernel (was just a guess where the problem was). After restart computer loaded just file, took a long time for it to start because of SELinux targeted policy relabel is required. Relabeling could take very long time depending on file size. I assumed that the update got messed up somehow and continued working with modified boot option. Couple of days ago, there was another kernel update. I installed it and same problem as before. This rules out corrupted update theory... Black screen right after 'BIOS' screen before OS gets loaded. I had to rescue system again... Below is copy of my grub.conf file. I am fairly new to LINUX (couple of years of experience), mostly development and basic config... nothing crazy. # grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE: You have a /boot partition. This means that # all kernel and initrd paths are relative to /boot/, eg. # root (hd0,0) # kernel /vmlinuz-version ro root=/dev/mapper/vg_obalyuk-lv_root # initrd /initrd-[generic-]version.img #boot=/dev/sda default=2 timeout=0 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu title Fedora (2.6.34.6-54.fc13.i686.PAE) root (hd0,0) kernel /vmlinuz-2.6.34.6-54.fc13.i686.PAE ro root=/dev/mapper/vg_obalyuk-lv_root rd_LVM_LV=vg_obalyuk/lv_root rd_LVM_LV=vg_obalyuk/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=us rhgb quiet initrd /initramfs-2.6.34.6-54.fc13.i686.PAE.img title Fedora (2.6.34.6-47.fc13.i686.PAE) root (hd0,0) kernel /vmlinuz-2.6.34.6-47.fc13.i686.PAE ro root=/dev/mapper/vg_obalyuk-lv_root rd_LVM_LV=vg_obalyuk/lv_root rd_LVM_LV=vg_obalyuk/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=us rhgb quiet initrd /initramfs-2.6.34.6-47.fc13.i686.PAE.img title Fedora (2.6.33.8-149.fc13.i686.PAE) root (hd0,0) kernel /vmlinuz-2.6.33.8-149.fc13.i686.PAE ro root=/dev/mapper/vg_obalyuk-lv_root rd_LVM_LV=vg_obalyuk/lv_root rd_LVM_LV=vg_obalyuk/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=us rhgb quiet initrd /initramfs-2.6.33.8-149.fc13.i686.PAE.img I like my system to be up to date... Let me know if I can post any other files that can be of help. Has anyone else had this problem? Does anyone has any ideas how to fix this problem? p.s. Anything helps, you ppl are great! thx for ur time.

  Read the article

• netbook intel GMA 3150 external monitor 1920x1080 flicker problem

  - by seyenne

  Dear all, i recently purchased a acer netbook (apsire one d260). It runs flawlessly. Yesterday I bought a samsung 23" TFT with a native resolution of 1920x1080. According to the information found in the internet and my local computer dealer, the intel chipset can handle the native resolution of the monitor. However, this is only partly the case. I use the VGA cabel to connect, the monitor instantly switches to the native resolution and now the problem: Occasionaly, especially the first 2 hours after booting up, I have a flickering all over the screen, sometimes the entire screen is shaking and spinning around like crazy. I figured out, that lowering the resolution avoids the flicker but this helps only for some time. I can rule out that it's the monitor's problem since I found no issues with another notebook. Right now, I have no problems with the netbook, for about 30 minutes I didn't experience any issues... But I don't know for how long, it occurs without warning :-) I'm worried that if I would bring the netbook back to the dealer and explain my problem, after testing it on an external screen in the local shop, everything works just fine... And I won't get helped with the problem because I can't prove it. (I'm currently in Thailand and over here, customer service is nothing like back home in Germany) What can I do? Is this a driver related issue? (I installed the latest GPU driver) Is it because of the VGA cable? (But why does it work sometimes without any problems and with no issues on the other notebook) I monitored the GPU/CPU temperature, nothing changes really over time..Can it simply be a faulty GPU and is a replacement justifiable? I'm really stressed now because for the time I'm writing, the flickering didn't occur...but for sure, soon or later it will happen again.. I Forgot to mention, the problem also happens if the netbook runs on battery, unplugged. So the only hardware that is plugged is the TFT screen. ...........and here it comes again, flickering has just begun. NEED HELP! Thank you all for reading through this and giving any suggestions if possible. Cheers

  Read the article

• Using Unit of Work design pattern / NHibernate Sessions in an MVVM WPF

  - by Echiban

  I think I am stuck in the paralysis of analysis. Please help! I currently have a project that Uses NHibernate on SQLite Implements Repository and Unit of Work pattern: http://blogs.hibernatingrhinos.com/nhibernate/archive/2008/04/10/nhibernate-and-the-unit-of-work-pattern.aspx MVVM strategy in a WPF app Unit of Work implementation in my case supports one NHibernate session at a time. I thought at the time that this makes sense; it hides inner workings of NHibernate session from ViewModel. Now, according to Oren Eini (Ayende): http://msdn.microsoft.com/en-us/magazine/ee819139.aspx He convinces the audience that NHibernate sessions should be created / disposed when the view associated with the presenter / viewmodel is disposed. He presents issues why you don't want one session per windows app, nor do you want a session to be created / disposed per transaction. This unfortunately poses a problem because my UI can easily have 10+ view/viewmodels present in an app. He is presenting using a MVP strategy, but does his advice translate to MVVM? Does this mean that I should scrap the unit of work and have viewmodel create NHibernate sessions directly? Should a WPF app only have one working session at a time? If that is true, when should I create / dispose a NHibernate session? And I still haven't considered how NHibernate Stateless sessions fit into all this! My brain is going to explode. Please help!

  Read the article

• .net layered design: return error code to forms indicating which controls have an error

  - by David Casillas

  Let's say I have a simple application. It tries to add a new entry to a database grabing the info from the user. The information is a tipical MasterDetail objetc like an invoice. The Invoice object used to collect the data has some simple atributes (Id, Date, etc...) and a List of InvoiceDetail, consisting of some simple atributes (invoiceId, productId, quantity, etc...) A form in the UI Layer collects the data from the user, creates an instance of Invoice and sends it to the Bussiness Layer. The Bussines layer sends the data to a Validation Module. If any error in the input is detected it has to return some kind of error code. The Bussiness Layer has to send the error code back to the Form to let the user correct the worng information. I want the application to display some kind of warning (a different background color for example) in every form control with an error. ¿What's a good aproach to I manage the errors to be able to inform the form which controls are wrong? ¿Can I create an error object?¿Use delegates?. I'm using VB.net but don't think this is relevant to the solution of the problem. P.D: Please suggest me some tags to this post.

  Read the article

• Processing a database queue across multiple threads - design advice

  - by rwmnau

  I have a SQL Server table full of orders that my program needs to "follow up" on (call a webservice to see if something has been done with them). My application is multi-threaded, and could have instances running on multiple servers. Currently, every so often (on a Threading timer), the process selects 100 rows, at random (ORDER BY NEWID()), from the list of "unconfirmed" orders and checks them, marking off any that come back successfully. The problem is that there's a lot of overlap between the threads, and between the different processes, and their's no guarantee that a new order will get checked any time soon. Also, some orders will never be "confirmed" and are dead, which means that they get in the way of orders that need to be confirmed, slowing the process down if I keep selecting them over and over. What I'd prefer is that all outstanding orders get checked, systematically. I can think of two easy ways do this: The application fetches one order to check at a time, passing in the last order it checked as a parameter, and SQL Server hands back the next order that's unconfirmed. More database calls, but this ensures that every order is checked in a reasonable timeframe. However, different servers may re-check the same order in succession, needlessly. The SQL Server keeps track of the last order it asked a process to check up on, maybe in a table, and gives a unique order to every request, incrementing its counter. This involves storing the last order somewhere in SQL, which I wanted to avoid, but it also ensures that threads won't needlessly check the same orders at the same time Are there any other ideas I'm missing? Does this even make sense? Let me know if I need some clarification.

  Read the article

• I can write code...but can't design well. Any suggestions?

  - by user396089

  I feel that I am good at writing code in bits and pieces, but my designs really suck. The question is how do I improve my designs (in order to become a better designer). I think schools and colleges do a good job of teaching people as to how to become good at mathematical problem solving, but lets admit the fact that most programs taught at school are generally around 1000 - 2000 lines long, which means that it is mostly an academic exercise and no way reflects the complexity of real world software (a few hundred thousand to millions of lines of code). This is where I believe that even projects like topcoder/project euler also won't be of much help, they might sharpen your mathematical problem solving ability - but you might become a theoretician programmer; someone who is more interested in the nice, clean stuff, and someone who is utterly un-interested in the day to day mundane and hairy stuff that most application programmers deal with. So my question is how do I improve my design skills? That is the ability to design small/medium scale applications that will go into a few thousand of lines of code? How can I learn design skills that would help me build a better html editor kit, or some graphics program like gimp?

  Read the article

• how to create multiple pages in Xcode iphone apps

  - by al7r

  Hi there, i am starting my experience with iphone sdk. and i have a question, which is i am trying to create two pages to the app but i don't know how to link them or design them. like when i start the Xcode i find one page named View to design in it, i want to make that page a welcoming page then the user choose one of the three choices he see in that page. Once he clicked on one of them the program take him to the next page or the page he chose. thank you

  Read the article

• Proper Way to Create Standards-Compliant Webpage Structure

  - by Sakamoto Kazuma

  I have been working through projects involving packages that do all the web design stuff for me for the past few years. I will admit that I have not been able to focus any on actual web design. I was wondering what the standard is these days for website layouts. Are layout-tables looked down upon now? Or are all layouts done with div tags and controlled through CSS? Are frames even used anymore? Note I am not talking about chart-table tables when I say layout tables.

  Read the article

• Product table, many kinds of product, each product has many parameters

  - by StoneHeart

  Hi, i'm have not much experience in table design. My goal is a product table(s), it must design to fix some requirement below: Support many kind of products (TV, Phone, PC, ...). Each kind of product has different set of parameters like: Phone will have Color, Size, Weight, OS... PC will have CPU, HDD, RAM... Set of parameters must be dynamic. You can add or edit any parameter you like. I don't want make a table for each kind of product. So I need help to find a correct solution. Thanks.

  Read the article

• Singleton: How should it be used

  - by Loki Astari

  Edit: From another question I provided an answer that has links to a lot of questions/answers about singeltons: More info about singletons here: So I have read the thread Singletons: good design or a crutch? And the argument still rages. I see Singletons as a Design Pattern (good and bad). The problem with Singleton is not the Pattern but rather the users (sorry everybody). Everybody and their father thinks they can implement one correctly (and from the many interviews I have done, most people can't). Also because everybody thinks they can implement a correct Singleton they abuse the Pattern and use it in situations that are not appropriate (replacing global variables with Singletons!). So the main questions that need to be answered are: When should you use a Singleton How do you implement a Singleton correctly My hope for this article is that we can collect together in a single place (rather than having to google and search multiple sites) an authoritative source of when (and then how) to use a Singleton correctly. Also appropriate would be a list of Anti-Usages and common bad implementations explaining why they fail to work and for good implementations their weaknesses. So get the ball rolling: I will hold my hand up and say this is what I use but probably has problems. I like "Scott Myers" handling of the subject in his books "Effective C++" Good Situations to use Singletons (not many): Logging frameworks Thread recycling pools /* * C++ Singleton * Limitation: Single Threaded Design * See: http://www.aristeia.com/Papers/DDJ_Jul_Aug_2004_revised.pdf * For problems associated with locking in multi threaded applications * * Limitation: * If you use this Singleton (A) within a destructor of another Singleton (B) * This Singleton (A) must be fully constructed before the constructor of (B) * is called. */ class MySingleton { private: // Private Constructor MySingleton(); // Stop the compiler generating methods of copy the object MySingleton(MySingleton const& copy); // Not Implemented MySingleton& operator=(MySingleton const& copy); // Not Implemented public: static MySingleton& getInstance() { // The only instance // Guaranteed to be lazy initialized // Guaranteed that it will be destroyed correctly static MySingleton instance; return instance; } }; OK. Lets get some criticism and other implementations together. :-)

  Read the article

• Using Agile development when building websites

  - by Sam

  Is it possible / plausible to apply Agile development to the website building process including planning, design and development?

  Read the article

• Is it easy to switch from relational to non-relational databases with Rails?

  - by Tam

  Good day, I have been using Rails/Mysql for the past while but I have been hearing about Cassandra, MongoDB, CouchDB and other document-store DB/Non-relational databases. I'm planning to explore them later as they might be better alternative for scalability. I'm planning to start an application soon. Will it make a different with Rails design if I move from relational to non-relational database? I know Rails migrations are database-agnostic but wasn't sure if moving to non-relational will make difference with design or not.

  Read the article

• where should we send notification for updating many views?

  - by Thanh-Cong Vo

  Hi all, I want to ask about software design. I have a task, the view controller handles UI event for calling a model manger to perform that task. After finishing, the model manager will callback to update the view. There have also other views who care about that task, and also want to update its own view when that task is finished. So I register a Notification for that task in each views. The problem is defining where should I send Notification, in Model manager or in the View who handles event and receives the callback from Model manager? What is better design? Shoud the model care about send this "common" task, or shoud the view? Thanks

  Read the article

• Where can I find free WPF controls and control templates?

  - by Geoffrey Chetwood

  Duplicate: Where can I find free WPF controls and control templates? I am looking for some recommendations on good places to find libraries of controls/templates/styles for WPF. I know about the usual places like Infragistics, but it seems to me that there should be some kind of community effort by now to share nice, clean, well written controls for WPF controls. I am not big on the design side, and it would be nice to fill out my personal libraries with some nice examples from people who are better at design. Any ideas/recommendations?

  Read the article

< Previous Page | 193 194 195 196 197 198 199 200 201 202 203 204  | Next Page >