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• Statically checking a Java app for link errors

  - by monorailkitty

  I have a scenario where I have code written against version 1 of a library but I want to ship version 2 of the library instead. The code has shipped and is therefore not changeable. I'm concerned that it might try to access classes or members of the library that existed in v1 but have been removed in v2. I figured it would be possible to write a tool to do a simple check to see if the code will link against the newer version of the library. I appreciate that the code may still be very broken even if the code links. I am thinking about this from the other side - if the code won't link then I can be sure there is a problem. As far as I can see, I need to run through the bytecode checking for references, method calls and field accesses to library classes then use reflection to check whether the class/member exists. I have three-fold question: (1) Does such a tool exist already? (2) I have a niggling feeling it is much more complicated that I imagine and that I have missed something major - is that the case? (3) Do you know of a handy library that would allow me to inspect the bytecode such that I can find the method calls, references etc.? Thanks!

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• Software usage analytics in C#

  - by TiernanO

  I have a project i am working on currently and would like to implement some sort of software tracking in the code. ideally, stuff like how often its launched. how long it runs for, feature tracking, etc. I already use Exceptioneer for unhandled exceptions, but would like something similar for usage tracking. this data should all be anonymous and ideally run as a service by someone else. and i would like to give the users the option to turn it off, if they so wish to... So, is this something i should implement myself, or are there third parties out there that do this sort of things? i know it might be a sticky area, but i have seen stats about iPhone app usage. they do it, so why cant we? (if the user agrees, of course) [Update] Based on the comments, i should have been more clear. this is a Winforms .NET 4. application, though i am thinking of updating it later with WCF. i would only be tracking my own application, though i would also want to know minor information about environment (Windows OS Version, SP, maybe proc and ram...)

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• Where can I get software-related legal advice?

  - by musicfreak

  Whenever someone asks a legal question here on SO, the response is usually something along the lines of "we are not lawyers." Okay, that's legitimate, but in that case, how can I talk to a lawyer about software-related legal matters? I could look through the phone book and find a local lawyer, but then I have no way of knowing whether the lawyer knows anything about software. (And I hear most local lawyers charge for your time, even if it's just a simple question.) Is there maybe some kind of online service for this sort of thing? For now, I'm just looking for some basic advice, so something free would be awesome, even if the "quality" is not as good. However, I'll still take any kind of paid services--I'll keep them in mind for the future. You can give me anything from a forum or QA site (like this one) to a professional service. Just remember that I'm looking specifically for software-related legal advice. I'm sure most lawyers know a thing or two about software, but I'd rather talk to someone who legitimately knows his stuff than someone who can only guess.

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• [C#] Dynamic user-interface, WPF or not?

  - by pieter.lowie

  Hi, I'm currently working at a application that helps people understand how to do there job. You can see it as a personal coach that guides them trough all the steps they need to do that no normal person could keep remembering. In my previous application we had the ability to show the user up to 4 pictures (what proves to be more then enough). The application would load the data and see how many pictures where in every instruction and then sort out the picture in the best fitting way without messing up the scale and resolution of the pictures. This all was done with GDI+ and worked very well. Ofc, change is something that always happens, my bosses came up with some great ideas. So they want to be able to see movies on the screen, animated gif's, 3D models that can rotate or animate. So I think we had pushed GDI+ to it's limits and it's time to look for something different. I have heard and readed about WPF but have no experience with it. Is it even possible to do all what I ask in WPF? And what about the old picture-merging thing I wrote, can we also get it done in wpf? I tried to make some things working but I didn't went as smooth as I hoped. I'm also concerned about the fact that the interface needs to be dynamic, the one moment it should be showing picture with some text above it, the other moment it should be showing another text with a video under it. I would love to hear some opinions here and if you got some other suggestions I should look into pls tell me. Thnx in advance PS: If WPF is the choice, should I convince my boss to change to .net 4.0?

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• (Rails) Creating multi-dimensional hashes/arrays from a data set...?

  - by humble_coder

  Hi All, I'm having a bit of an issue wrapping my head around something. I'm currently using a hacked version of Gruff in order to accommodate "Scatter Plots". That said, the data is entered in the form of: g.data("Person1",[12,32,34,55,23],[323,43,23,43,22]) ...where the first item is the ENTITY, the second item is X-COORDs, and the third item is Y-COORDs. I currently have a recordset of items from a table with the columns: POINT, VALUE, TIMESTAMP. Due to the "complex" calculations involved I must grab everything using a single query or risk way too much DB activity. That said, I have a list of items for which I need to dynamically collect all data from the recordset into a hash (or array of arrays) for the creation of the data items. I was thinking something like the following: @h={} e = Events.find_by_sql(my_query) e.each do |event| @h["#{event.Point}"][x] = event.timestamp @h["#{event.Point}"][y] = event.value end Obviously that's not the correct syntax, but that's where my brain is going. Could someone clean this up for me or suggest a more appropriate mechanism by which to accomplish this? Basically the main goal is to keep data for each pointname grouped (but remember the recordset has them all). Much appreciated. EDIT 1 g = Gruff::Scatter.new("600x350") g.title = self.name e = Event.find_by_sql(@sql) h ={} e.each do |event| h[event.Point.to_s] ||= {} h[event.Point.to_s].merge!({event.Timestamp.to_i,event.Value}) end h.each do |p| logger.info p[1].values.inspect g.data(p[0],p[1].keys,p[1].values) end g.write(@chart_file)

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• Jquery Ajax + PHP

  - by Kris.Mitchell

  I am having problems with jQuery Ajax and PHP I have my php file set up to echo the data I am gathering from a mysql database. I have verified that the database is returning something and that the string at the end of the function actually contains data. What is happening though, is that it looks like the php echo is happening before the ajax call, causing the php data to be displayed at the top of the page, and not below in proper div. I think it might have something to do with timing of the ajax and the php call, but I am not sure. So, why is the data not getting caught by the .ajax and thrown into the div? Thanks for the help! jQuery $(document).ready(function() { $.ajax({ url: "../database_functions.php", type: "GET", data: "cat=jw&sub=pi&sort=no", cache: false, success: function (html) { alert("Success!"); $('#product-list').html(html); } }); }); PHP echo "Hello World";

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• Javascript global object calls function?

  - by Troels

  Hello stackoverflow I have a very odd problem with javascript. My code is rather long so here is an example of the structure and the problem: var x = new function f() { this.id = ""; } function g(obj) { if (x.id == "") { ... obj.firstChild.setAttribute("onclick", "javascript:o();"); ... x.id = obj.id; } else if (x.id != obj.id) { ... x.id = ""; g(obj); } } function o() { ... if (something == something) { ... } else { ... x.id = ""; // if-statement of the g() function is called here? } } As you can see, the if-statement of the g() function is for some reason called or re-run upon x.id being changed. I simply cannot understand this, because they are not in the same scope, and changing a variable should under no circumstances trigger anything? Any help would be greatly appreciated.

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• Why is it that an int in C++ that isnt initialized (then used) doesn't return an error?

  - by omizzle

  I am new to C++ (just starting). I come from a Java background and I was trying out the following piece of code that would sum the numbers between 1 and 10 (inclusive) and then print out the sum: /* * File: main.cpp * Author: omarestrella * * Created on June 7, 2010, 8:02 PM */ #include <cstdlib> #include <iostream> using namespace std; int main() { int sum; for(int x = 1; x <= 10; x++) { sum += x; } cout << "The sum is: " << sum << endl; return 0; } When I ran it it kept printing 32822 for the sum. I knew the answer was supposed to be 55 and realized that its print the max value for a short (32767) plus 55. Changing int sum; to int sum = 0; would work (as it should, since the variable needs to be initialized!). Why does this behavior happen, though? Why doesnt the compiler warn you about something like this? I know Java screams at you when something isnt initialized. Thank you.

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• How can I get HTML to link to a browser (or system) specified URL?

  - by MrHatken

  Hi All, I'd like to be able to create a "HTML link" that the user can click on and be taken to an URL (location) specified either in the browser (preferences?) or system environment. Is this possible? Any suggestions on how to do it please? For example, it may look something like this (or alternatively it could be a clickable image or even a submit button): "Click here to go to your preferred news site." When the user clicks on "here" the browser would go to a location specified not in the HTML but somehow in the browser (preferences?) or some system environment variable (OS specific etc.) Of course, the user would have to set up this preference or environment variable (or have some local application or better Web page that could set it - when approved by the user). This is sort of like most OS these days allow you to set "preferred app" for image processing or playing media. I would like to set preferred Web sites for certain tasks. Thanks for any suggestions. Hopefully with Javascript and modern browsers and perhaps HTML 5 something like this is possible. Cheers, Ashley.

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• Code won't work under mono, any ideas whats wrong?

  - by JL

  Mono won't fire the following code: I get internal server error 500, error writing request error. Code works perfectly under normal .net.... any ideas why its broken and how to fix it? [WebServiceBinding] public class testService : System.Web.Services.Protocols.SoapHttpClientProtocol { private string DummySoapRequest = @"<?xml version=""1.0"" encoding=""utf-8""?> <soap:Envelope xmlns:soap=""http://schemas.xmlsoap.org/soap/envelope/"" xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema""> <soap:Body> <DummyOperation xmlns=""http://mynamespace.com""> </DummyOperation> </soap:Body> </soap:Envelope>"; public void SendDummyRequest() { System.Net.WebRequest req = GetWebRequest(new Uri(Url)); req.Headers.Add("SOAPAction", ""); req.ContentType = "text/xml;charset=\"utf-8\""; req.Method = "POST"; using (Stream stm = req.GetRequestStream()) { using (StreamWriter stmw = new StreamWriter(stm)) { stmw.Write(DummySoapRequest); } } System.Net.WebResponse response = req.GetResponse(); } }

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• Need a refresher course on property access...

  - by Code Sherpa

  Hi. I need help with accessing class properties within a given class. For example, take the below class: public partial class Account { private Profile _profile; private Email _email; private HostInfo _hostInfo; public Profile Profile { get { return _profile; } set { _profile = value; } } public Email Email { get { return _email; } set { _email = value; } } public HostInfo HostInfo { get { return _hostInfo; } set { _hostInfo = value; } } In the class "Account" exists a bunch of class properties such as Email or Profile. Now, when I want to access those properties at run-time, I do something like this (for Email): _accountRepository = ObjectFactory.GetInstance<IAccountRepository>(); string username = Cryptography.Decrypt(_webContext.UserNameToVerify, "verify"); Account account = _accountRepository.GetAccountByUserName(username); if(account != null) { account.Email.IsConfirmed = true; But, I get "Object reference not set..." for account.Email... Why is that? How do I access Account such that account.Email, account.Profile, and so on returns the correct data for a given AccountId or UserName. Here is a method that returns Account: public Account GetAccountByUserName(string userName) { Account account = null; using (MyDataContext dc = _conn.GetContext()) { try { account = (from a in dc.Accounts where a.UserName == userName select a).FirstOrDefault(); } catch { //oops } } return account; } The above works but when I try: account = (from a in dc.Accounts join em in dc.Emails on a.AccountId equals em.AccountId join p in dc.Profiles on em.AccountId equals p.AccountId where a.UserName == userName select a).FirstOrDefault(); I am still getting object reference exceptions for my Email and Profile properties. Is this simply a SQL problem or is there something else I need to be doing to be able to fully access all the properties within my Account class? Thanks!

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• Is locking on the requested object a bad idea?

  - by Quick Joe Smith

  Most advice on thread safety involves some variation of the following pattern: public class Thing { private static readonly object padlock = new object(); private string stuff, andNonsense; public string Stuff { get { lock (Thing.padlock) { if (this.stuff == null) this.stuff = "Threadsafe!"; } return this.stuff; } } public string AndNonsense { get { lock (Thing.padlock) { if (this.andNonsense == null) this.andNonsense = "Also threadsafe!"; } return this.andNonsense; } } // Rest of class... } In cases where the get operations are expensive and unrelated, a single locking object is unsuitable because a call to Stuff would block all calls to AndNonsense, degrading performance. And rather than create a lock object for each call, wouldn't it be better to acquire the lock on the member itself (assuming it is not something that implements SyncRoot or somesuch for that purpose? For example: public string Stuff { get { lock (this.stuff) { // Pretend that this is a very expensive operation. if (this.stuff == null) this.stuff = "Still threadsafe and good?"; } return this.stuff; } } Strangely, I have never seen this approach recommended or warned against. Am I missing something obvious?

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• Problem shrinking with StretchBlt()

  - by SparkyNZ

  Hi. I have some code that paints my own rectangular buttons based on a source bitmap. Most of the time the destination buttons are bigger than my source bitmap image and StretchBlt works fine. However, when the destination is smaller than the source image, StretchBlt refuses to fill the entire destination area. I know StretchBlt isn't great on quality when it comes to scaling down images but I'm not too concerned about that. I just don't want missing pixels. Here a link with the source image at the top and destination at the bottom: link text Note, I am actually shrinking parts of the source image into the destination. I am not shrinking the entire image down. So for example, I copy the corners size for size with BitBlt() then I stretch (squash) the horizontal pixel data between the corners from the source image into the destination DC. There is no fault with my source and destination coordinates. If I change from SRCCOPY to WHITENESS, the entire area fills with white as you'd expect. There is no grey bar where pixels haven't copied as you see in the Broken.bmp image above. Has anyone had this problem before, and if so, can somebody please suggest a solution? Cheers

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• Java constructor using generic types

  - by Beer Me

  I'm having a hard time wrapping my head around Java generic types. Here's a simple piece of code that in my mind should work, but I'm obviously doing something wrong. Eclipse reports this error in BreweryList.java: The method breweryMethod() is undefined for the type <T> The idea is to fill a Vector with instances of objects that are a subclass of the Brewery class, so the invocation would be something like: BreweryList breweryList = new BreweryList(BrewerySubClass.class, list); BreweryList.java package com.beerme.test; import java.util.Vector; public class BreweryList<T extends Brewery> extends Vector<T> { public BreweryList(Class<T> c, Object[] j) { super(); for (int i = 0; i < j.length; i++) { T item = c.newInstance(); // breweryMethod() is an instance method // of Brewery, of which <T> is a subclass (right?) c.breweryMethod(); // "The method breweryMethod() is undefined // for the type <T>" } } } Brewery.java package com.beerme.test; public class Brewery { public Brewery() { super(); } protected void breweryMethod() { } } BrewerySubClass.java package com.beerme.test; public class BrewerySubClass extends Brewery { public BrewerySubClass() { super(); } public void brewerySubClassMethod() { } } I'm sure this is a complete-generics-noob question, but I'm stuck. Thanks for any tips!

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• IIS 6.0 Rewrite rules for Wordpress (Forward slash not working and other things)

  - by DigitalBlade

  Hi, I am using Wordpress 3.0.4 on IIS 6.0 and Windows Server 2003, hosted by a company. I was having lots of issues using permalinks. I have fixed most, but now I have an issue with a forward-slash not being added to the address. This would be fine on most websites, but not on IIS for some reason. Specifically, if I go to "mysite.com/wp-admin" I can log-in and get to the dashboard, but as soon as I click anything there i am redirected to a broken link. For example: "mysite.com/post-new.php". If I add the slash at the end it's fine. So I tried to have a rewrite rule to automatically add the slash to such address: RewriteRule /wp-admin /wp-admin/ [L] But it still doesn't work. For your reference, here's the complete file: [ISAPI_Rewrite] RewriteBase / RewriteCond ${REQUEST_FILENAME} !-f RewriteCond ${REQUEST_FILENAME} !-d # For special WordPress folders (e.g. theme, admin, etc.) RewriteRule /wp-admin /wp-admin/ [L] RewriteRule /wp-(.*) /wp-$1 [L] RewriteRule /(.*\.(?:jpg|jpeg|gif|css|txt|xml|html|png|js)) /$1 [I,L] # Rules to ensure that normal content gets through RewriteRule /images/(.*) /images/$1 [L] RewriteRule /favicon.ico /favicon.ico [L] RewriteRule /robots.txt /robots.txt [L] RewriteRule /phpmyadmin/(.*) /phpmyadmin/$1 [L] RewriteRule /phpmyadmin /phpmyadmin/ [L] # For all WordPress pages RewriteRule ^/$ /index.php [L] RewriteRule /(.*) /index.php/$1 [L] Any ideas? Thanks in advance

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• How do C++ compilers actually pass reference parameters?

  - by T.E.D.

  This question came about as a result of some mixed-langauge programming. I had a Fortran routine I wanted to call from C++ code. Fortran passes all its parameters by reference (unless you tell it otherwise). So I thought I'd be clever (bad start right there) in my C++ code and define the Fortran routine something like this: extern "C" void FORTRAN_ROUTINE (unsigned & flag); This code worked for a while but (of course right when I needed to leave) suddenly started blowing up on a return call. Clear indication of a munged call stack. Another engineer came behind me and fixed the problem, declaring that the routine had to be deinfed in C++ as extern "C" void FORTRAN_ROUTINE (unsigned * flag); I'd accept that except for two things. One is that it seems rather counter-intuitive for the compiler to not pass reference parameters by reference, and I can find no documentation anywhere that says that. The other is that he changed a whole raft of other code in there at the same time, so it theoretically could have been another change that fixed whatever the issue was. So the question is, how does C++ actually pass reference parameters? Is it perhaps free to do copy-in, copy-out for small values or something? In other words, are reference parameters utterly useless in mixed-language programming? I'd like to know so I don't make this same code-killing mistake ever again.

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• Is it possible to create a Mac OS specific CSS to fix font difference ?

  - by Gabriel

  I'm working on a project with a designer and he insisted on using some specific font for titles and various elements in the page. So we're using a font kit to embed with @font-face. It's working perfectly on PC (Firefox, IE 7 and 8, Chrome, Safari) but on Mac OS (Safari and Firefox) the fonts are not vertically aligned the same way. After looking on the Web, I didn't find any solution for this except "there always been differences between browsers and platforms, live with it". I know that fonts are never rendered exactly the same across platforms, but this time it's not something like the font looks more bold or something like that. The font looks as if it's baseline is completely different between Windows and Mac OS X. On Mac OS, the font, at a size of 16px is 3px higher than on PC. So I'm looking for a backup solution : is there a way to create a CSS specifically for Mac OS users? I do not want to target only Safari because Safari PC is ok, and Firefox Mac is not ok. Or if you have a solution to fix the baseline difference that does not require a specific CSS file, I'd be happy to hear it. Thanks!

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• Invoking code both before and after WebControl.Render method

  - by Dirk

  I have a set of custom ASP.NET server controls, most of which derive from CompositeControl. I want to implement a uniform look for "required" fields across all control types by wrapping each control in a specific piece of HTML/CSS markup. For example: <div class="requiredInputContainer"> ...custom control markup... </div> I'd love to abstract this behavior in such a way as to avoid having to do something ugly like this in every custom control, present and future: public class MyServerControl : TextBox, IRequirableField { public IRequirableField.IsRequired {get;set;} protected override void Render(HtmlTextWriter writer){ RequiredFieldHelper.RenderBeginTag(this, writer) //render custom control markup RequiredFieldHelper.RenderEndTag(this, writer) } } public static class RequiredFieldHelper{ public static void RenderBeginTag(IRequirableField field, HtmlTextWriter writer){ //check field.IsRequired, render based on its values } public static void RenderEndTag(IRequirableField field, HtmlTextWriter writer){ //check field.IsRequired , render based on its values } } If I was deriving all of my custom controls from the same base class, I could conceivably use Template Method to enforce the before/after behavior;but I have several base classes and I'd rather not end up with really a convoluted class hierarchy anyway. It feels like I should be able to design something more elegant (i.e. adheres to DRY and OCP) by leveraging the functional aspects of C#, but I'm drawing a blank.

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• F# - POCO Class

  - by ebb

  Hey there! I'm trying to write a POCO class in proper F#... But something is wrong.. The C# code that I want to "translate" to proper F# is: public class MyTest { [Key] public int ID { get; set; } public string Name { get; set; } } The closest I can come to the above code in F# is something like: type Mytest() = let mutable _id : int = 0; let mutable _name : string = null; [<KeyAttribute>] member x.ID with public get() : int = _id and public set(value) = _id <- value member x.Name with public get() : string = _name and public set value = _name <- value However when I try to access the properties of the F# version it just returns a compile error saying "Lookup on object of indeterminate type based on information prior to this program point. A type annotation may be needed prior to this program point to constrain the type of the object. This may allow the lookup to be resolved." The code thats trying to get the property is a part of my Repository (I'm using EF Code First). module Databasethings = let GetEntries = let ctx = new SevenContext() let mydbset = ctx.Set<MyTest>() let entries = mydbset.Select(fun item -> item.Name).ToList() // This line comes up with a compile error at "item.Name" (the compile error is written above) entries What the hell is going on? Thanks in advance!

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• Xcode 4: nib files not loading when run, can't find UI elements

  - by Jordan

  So, I just downloaded Xcode 4 and installed it. I was actually quite looking forward to the single window and integrated IB... - However, when I open and run one of my projects, the nib files that the project uses don't seem to load. Instead I'm left looking at a blank white screen (iPhone). This project ran well and fine on Xcode 3.2. So I thought... this can't be that hard to fix. So I opened up a nib file, thinking that maybe editing or creating a new one from scratch could point me in the right direction. But I can't find the old resources panel from interface builder anywhere. How am I meant to create a new view or add buttons? I know I'm probably just missing something obvious :s Did anyone else have the same nib file problems - is there a fix (or something stupidly simple that I'm forgetting about)? - EDIT: Ok. If I background and un-background the app, the view loads fine. But this happens every time I build, on both iPhone and iOS simulator, i.e. the app doesn't work properly until it's been backgrounded. All the code for loading the view follows from - (void)applicationDidFinishLaunching:(UIApplication *)application. Now I am really confused. - Thanks :)

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• Schema for storing "binary" values, such as Male/Female, in a database

  - by latentflip

  Intro I am trying to decide how best to set up my database schema for a (Rails) model. I have a model related to money which indicates whether the value is an income (positive cash value) or an expense (negative cash value). I would like separate column(s) to indicate whether it is an income or an expense, rather than relying on whether the value stored is positive or negative. Question: How would you store these values, and why? Have a single column, say Income, and store 1 if it's an income, 0 if it's an expense, null if not known. Have two columns, Income and Expense, setting their values to 1 or 0 as appropriate. Something else? I figure the question is similar to storing a person's gender in a database (ignoring aliens/transgender/etc) hence my title. My thoughts so far Lookup might be easier with a single column, but there is a risk of mistaking 0 (false, expense) for null (unknown). Having seperate columns might be more difficult to maintain (what happens if we end up with a 1 in both columns? Maybe it's not that big a deal which way I go, but it would be great to have any concerns/thoughts raised before I get too far down the line and have to change my code-base because I missed something that should have been obvious! Thanks, Philip

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• What's the correct place to share application logic in CakePHP?

  - by Pichan

  I guess simple answer to the question would be a component. Although I agree, I feel weird having to write a component for something so specific. For example, let's say I have a table of users. When a user is created, it should form a chain reaction of events, initiating different kinds of data related to the user all around the database. I figured it would be best to avoid directly manipulating the database from different controllers and instead pack all that neatly in a method. However since some logic needs to be accesed separately, I really can't have the whole package in a single method. Instead I thought it would be logical to break it up to smaller pieces(like $userModelOrController->createNew() and $candyStorageModelOrController->createNew()) that only interact with their respective database table. Now, if the logic is put to the model, it works great until I need to use other models. Of course it's possible, but when compared to loading models in a controller, it's not that simple. It's like a Cake developer telling me "Sure, it's possible if you want to do it that way but that's not how I would do it". Then, if the logic is put to the controller, I can access other models really easy through $this->loadModel(), but that brings me back to the previously explained situation since I need to be able to continue the chain reaction indefinitely. Accessing other controllers from a controller is possible, but again there doesn't seem to be any direct way of doing so, so I'm guessing I'm still not doing it right. By using a component this problem could be solved easily, since components are available to every controller I want. But like I wrote at the beginning, it feels awkward to create a component specifically for this one task. To me, components seem more like packages of extra functionality(like the core components) and not something to share controller-specific logic. Since I'm new to this whole MVC thing, I could've completely misunderstood the concept. Once again, I would be thankful if someone pointed me to the right direction :)

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• Scalability 101: How can I design a scalable web application using PHP?

  - by Legend

  I am building a web-application and have a couple of quick questions. From what I learnt, one should not worry about scalability when initially building the app and should only start worrying when the traffic increases. However, this being my first web-application, I am not quite sure if I should take an approach where I design things in an ad-hoc manner and later "fix" them. I have been reading stories about how people start off with an app that gets millions of users in a week or two. Not that I will face the same situation but I can't help but wonder, how do these people do it? Currently, I bought a shared hosting account on Lunarpages and that got me started in building and testing the application. However, I am interested in learning how to build the same application in a scalable-manner using the cloud, for instance, Amazon's EC2. From my understanding, I can see a couple of components: There is a load balancer that first receives requests and then decides where to route each request This request is then handled by a server replica that then processes the request and updates (if required) the database and sends back the response to the client If a similar request comes in, then a caching mechanism like memcached kicks into picture and returns objects from the cache A blackbox that handles database replication Specifically, I am trying to do the following: Setting up a load balancer (my homework revealed that HAProxy is one such load balancer) Setting up replication so that databases can be synchronized Using memcached Configuring Apache to work with multiple web servers Partitioning application to use Amazon EC2 and Amazon S3 (my application is something that will need great deal of storage) Finally, how can I avoid burning myself when using Amazon services? Because this is just a learning phase, I can probably do with 2-3 servers with a simple load balancer and replication but until I want to avoid paying loads of money accidentally. I am able to find resources on individual topics but am unable to find something that starts off from the big picture. Can someone please help me get started?

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• Tips for submitting a library to Boost?

  - by AraK

  Hi everyone, Summer is coming, and a group of friends and I are getting ready for it :) We decided to build a compile-time Arbitrary precision Unsigned Integers. We would like to provide a set of integers algorithms(functions) with the library. We have seen a number of requests for such a library(SoC2010, C++0x Standard Library wishlist). Also, a regular run-time bigint is requested usually with that, but we don't want to go into the hassle of memory management. The idea came to me from a library called TTMath, unfortunately this library works only on specific platforms because Assembly was used extensively in the library. We would like to write a standard library, depending on the C++ standard library and Boost. Also, we would like to use the available C++0x facilities in current compilers like user-defined literals and others. This would technically make the library non-standard for a while, but we think that it is a matter of time the new standards will be official. Your hints on the whole process including design, implementation, documentation, maintainable of the library are more than welcom. We are a group of students and fresh graduates who are looking for something interesting in the summer, but we see that Boost is full of gurus and we don't want to forget something too obvious. We are communicating on-line, so there is no shared white-boards :( Thanks,

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• Client Side Only Cookies

  - by Mike Jones

  I need something like a cookie, but I specifically don't want it going back to the server. I call it a "client side session cookie" but any reasonable mechanism would be great. Basically, I want to store some data encrypted on the server, and have the user type a password into the browser. The browser decrypts the data with the password (or creates and encrypts the data with the password) and the server stores only encrypted data. To keep the data secure on the server, the server should not store and should never receive the password. Ideally there should be a cookie session expiration to clean up. Of course I need it be available on multiple pages as the user walks through the web site. The best I can come up with is some sort of iframe mechanism to store the data in javascript variables, but that is ugly. Does anyone have any ideas how to implement something like this? FWIW, the platform is ASP.NET, but I don't suppose that matters. It needs to support a broad range of browsers, including mobile. In response to one answer below, let me clarify. My question is not how to achieve the crypto, that isn't a problem. The question is where to store the password so that it is persistent from page to page, but not beyond a session, and in such a way that the server doesn't see it.

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