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• How to update a custom dependency property when the datasource list changes

  - by John

  Hi We have a user control with a custom dependency property (DP). The DP is bound to an ObservableCollection. When a new item is added to the collection programatically, the databinding does not update the target DP. Why? We think it's because, unfortunately, in our case the target is not a ListBox or ListView, but a Canvas. The DP, when changed or initialized, is supposed to draw a Shape (!) onto the Canvas, and the shape's position and size is bound to the collection item's two properties: WIDTH, LEFT. Ideally we don't want to clear the Canvas and redraw all items just becasue one has been added (or deleted). But how? So: How can the custom DP take care of drawing the shape for the new collection item? What callback do we need, at what point in time does this have to happen, and what specific MetaDataOptions might there? Also, are there any good resources out there concerning all these dependency property options. They are quite confusing. MSDN does not really help with what we're trying to do. Thanks!

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• LIBPCAP and WIRESHARK Capture on PPP

  - by user655629

  Hi, I have written a small bridge program using LIBPCAP API. I have installed Winpcap 3.1 Beta for support in order to capture from a PPP interface. What i do is, I capture from the PPP interface through my LIBPCAP program and send the traffic to another Ethernet interface in my computer. Then i connect this Ethernet Interface to another Ethernet Interface at another computer where i monitor it through Wireshark. So in short my PPP-Ethernet Bridge is on computer 1. And Another computer2 directly connected to computer1 on Ethernet monitors the incoming traffic from the bridge through wireshark. The problem i face is that when i capture PPP traffic through wireshark in computer1, i see reasonable delay between the packets. But when i use my LIBPCAP program to capture and relay traffic and check the traffic on computer 2 using Wireshark it gives jumps of 0.5seconds delay after some packets. This is quite unexplainable to me. I dont understand how wireshark PPP direct capture on computer 1 does not give delay and LIBPCAP program is giving delay. I have checked my bridge for Ethernet to Ethernet relaying and there is no delay like the one i am experiencing in case of PPP-Ethernet. a higher delay between packets is acceptable but such a BIG delay after a couple of packets is unacceptable. Please help if you can. Best Regards FIKA

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• Precision of cos(atan2(y,x)) versus using complex <double>, C++

  - by Ivan

  Hi all, I'm writing some coordinate transformations (more specifically the Joukoswky Transform, Wikipedia Joukowsky Transform), and I'm interested in performance, but of course precision. I'm trying to do the coordinate transformations in two ways: 1) Calculating the real and complex parts in separate, using double precision, as below: double r2 = chi.x*chi.x + chi.y*chi.y; //double sq = pow(r2,-0.5*n) + pow(r2,0.5*n); //slow!!! double sq = sqrt(r2); //way faster! double co = cos(atan2(chi.y,chi.x)); double si = sin(atan2(chi.y,chi.x)); Z.x = 0.5*(co*sq + co/sq); Z.y = 0.5*si*sq; where chi and Z are simple structures with double x and y as members. 2) Using complex : Z = 0.5 * (chi + (1.0 / chi)); Where Z and chi are complex . There interesting part is that indeed the case 1) is faster (about 20%), but the precision is bad, giving error in the third decimal number after the comma after the inverse transform, while the complex gives back the exact number. So, the problem is on the cos(atan2), sin(atan2)? But if it is, how the complex handles that? Thanks!

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• Printing a sideways triangle in java

  - by Will

  I'm trying to print a sideways triangle in java. If the user enters 5, the output should be: * *** ***** *** * If the user enters 6, the output should be: * *** ***** ***** *** * I've gotten it to work for the case when the user enters 5, 3, or 1 but my code seems to work for those three cases only. I was wondering if anyone could help me get my code working for more cases. Here it is: public void printArrow( int n ) { int asterisks = 1; for ( int i = 0; i <= n/2; i++ ) { for ( int j = i; j < asterisks; j++ ) { System.out.print( "*" ); } asterisks += 3; System.out.println(); } asterisks = asterisks / 2 - 2; for ( int i = 0; i < n/2; i++ ) { for ( int k = i; k < asterisks; k++ ) { System.out.print( "*" ); } if ( i == 1 ) { System.out.print( "*" ); } asterisks -= 2; System.out.println(); } }

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• IE event callback object JavaScript

  - by Randy Hall

  I may be WAY off on my terminology, so please feel free to correct me. Perhaps this is why I cannot seem to find anything relevant. No libraries, please. I have an event handler, which invokes a callback function. Fancy, right? In IE<9 the this object in the handler is the window. I don't know why, or how to access the correct object. if (document.addEventListener){ element.addEventListener(event, callback, false); } else { element.attachEvent('on' +event, callback); } This part DOES WORK. This part doesn't: function callback(event){ console.log(this); } this in IE is returning [object Window], whereas it returns the element that called the callback function in every other browser. This is cut down significantly from my full script, but this should be everything that's relevant. EDIT This link provided by @metadings How to reference the caller object ("this") using attachEvent is very close. However, there are still two issues. 1) I need to get both the event object and the DOM element calling this function. 2) This event is handled delegation style: there may be child DOM elements firing the event, meaning event.target is not necessarily (and in my case, not typically) the element with the listener.

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• Flex wordwrap issue with multiple text instances

  - by Craig Myles

  Hi, I have a scenario where I want to dynamically add words of text to a container so that it forms a paragraph of text which is wrapped neatly according to the size of the parent container. Each text element will have differing formatting, and will have differing user interaction options. For example, imagine the text " has just spoken out about ". Each word will be added to the container one at a time, at run time. The username in this case would be bold, and if clicked on will trigger an event. Same with the news article. The rest of the text is just plain text which, when clicked on, would do nothing. Now, I'm using Flex 3 so I don't have access to the fancy new text formatting tools. I've implemented a solution where the words are plotted onto a canvas, but this means that the words are wrapped at a particular y position (an arbitrary value I've chosen). When the container is resized, the words still wrap at that position which leaves lots of space. I thought about adding each text element to an Array Collection and using this as a datasource for a Tile List, but Tile Lists don't support variable column widths (in my limited knowledge) so each word would use the same amount of space which isn't ideal. Does anyone know how I can plot words onto a container so that I can retain formatting, events and word wrapping at paragraph level, even if the container is resized?

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• Display hidden li based on class

  - by kylex

  I have the following list structure: <ul> <li>One</li> <li>Two <ul> <li class="active">Two-1</li> <li>Two-2</li> </ul> </li> <li>Three <ul> <li>Three-1</li> </ul> </li> </ul> with the following CSS: ul li ul{ display:none; } ul li:hover ul{ display:block; } What I would like is this: When an li class is active, the entire structure down until the active class gets displayed. so in the case provided the following would show, along with the top level: One Two Two-1 Two-2 Three I'd like either a CSS or jQuery implementation (or mixture of the two) if possible.

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• Passing youtube video id from video feed to flash

  - by Grant Anderson

  I'm working on a flash web application (Actionscript 2.0) for my honours project but am having trouble embedding youtube videos. Basically the user selects symbols which queries the youtube api with certain tags depending on the symbols chosenand a random video is then picked from the first 30 videos. I have this working using the following code: on (release) { url="http://gdata.youtube.com/feeds/api/videos?q=danger+passion&orderby=published&start-index="+random(30)+"&max-results=1&v=2" getURL(url); } but this just displays a webpage with a link to the youtube video. This is the code I'll be using as the foundations for the player: // create a MovieClip to load the player into var ytplayer:MovieClip = _root.createEmptyMovieClip("ytplayer", 1); // create a listener object for the MovieClipLoader to use var ytPlayerLoaderListener:Object = { onLoadInit: function() { // When the player clip first loads, we start an interval to // check for when the player is ready loadInterval = setInterval(checkPlayerLoaded, 250); } }; var loadInterval:Number; function checkPlayerLoaded():Void { // once the player is ready, we can subscribe to events, or in the case of // the chromeless player, we could load videos if (ytplayer.isPlayerLoaded()) { ytplayer.addEventListener("onStateChange", onPlayerStateChange); ytplayer.addEventListener("onError", onPlayerError); clearInterval(loadInterval); } } function onPlayerStateChange(newState:Number) { trace("New player state: "+ newState); } function onPlayerError(errorCode:Number) { trace("An error occurred: "+ errorCode); } // create a MovieClipLoader to handle the loading of the player var ytPlayerLoader:MovieClipLoader = new MovieClipLoader(); ytPlayerLoader.addListener(ytPlayerLoaderListener); // load the player ytPlayerLoader.loadClip("http://www.youtube.com/v/pv5zWaTEVkI", ytplayer); can anyone help me on how to get the id of the video (for example: pv5zWaTEVkI) from the feed? Or how to send a query from flash which will return the video url/id as opposed to the url of a feed. Any help would be much appreciated as my hand in rather soon. Thanks

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• Best practice - When to evaluate conditionals of function execution

  - by Tesserex

  If I have a function called from a few places, and it requires some condition to be met for anything it does to execute, where should that condition be checked? In my case, it's for drawing - if the mouse button is held down, then execute the drawing logic (this is being done in the mouse movement handler for when you drag.) Option one says put it in the function so that it's guaranteed to be checked. Abstracted, if you will. public function Foo() { DoThing(); } private function DoThing() { if (!condition) return; // do stuff } The problem I have with this is that when reading the code of Foo, which may be far away from DoThing, it looks like a bug. The first thought is that the condition isn't being checked. Option two, then, is to check before calling. public function Foo() { if (condition) DoThing(); } This reads better, but now you have to worry about checking from everywhere you call it. Option three is to rename the function to be more descriptive. public function Foo() { DoThingOnlyIfCondition(); } private function DoThingOnlyIfCondition() { if (!condition) return; // do stuff } Is this the "correct" solution? Or is this going a bit too far? I feel like if everything were like this function names would start to duplicate their code. About this being subjective: of course it is, and there may not be a right answer, but I think it's still perfectly at home here. Getting advice from better programmers than I is the second best way to learn. Subjective questions are exactly the kind of thing Google can't answer.

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• Python: Best way to check for Python version in program that uses new language features?

  - by Mark Harrison

  If I have a python script that requires at least a particular version of python, what is the correct way to fail gracefully when an earlier version of python is used to launch the script? How do I get control early enough to issue an error message and exit? For example, I have a program that uses the ternery operator (new in 2.5) and "with" blocks (new in 2.6). I wrote a simple little interpreter-version checker routine which is the first thing the script would call ... except it doesn't get that far. Instead, the script fails during python compilation, before my routines are even called. Thus the user of the script sees some very obscure synax error tracebacks - which pretty much require an expert to deduce that it is simply the case of running the wrong version of python. update I know how to check the version of python. The issue is that some syntax is illegal in older versions of python. Consider this program: import sys if sys.version_info < (2, 4): raise "must use python 2.5 or greater" else: # syntax error in 2.4, ok in 2.5 x = 1 if True else 2 print x When run under 2.4, I want this result $ ~/bin/python2.4 tern.py must use python2.5 or greater and not this result: $ ~/bin/python2.4 tern.py File "tern.py", line 5 x = 1 if True else 2 ^ SyntaxError: invalid syntax (channeling for a coworker)

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• If attacker has original data and encrypted data, can they determine the passphrase?

  - by Brad Cupit

  If an attacker has several distinct items (for example: e-mail addresses) and knows the encrypted value of each item, can the attacker more easily determine the secret passphrase used to encrypt those items? Meaning, can they determine the passphrase without resorting to brute force? This question may sound strange, so let me provide a use-case: User signs up to a site with their e-mail address Server sends that e-mail address a confirmation URL (for example: https://my.app.com/confirmEmailAddress/bill%40yahoo.com) Attacker can guess the confirmation URL and therefore can sign up with someone else's e-mail address, and 'confirm' it without ever having to sign in to that person's e-mail account and see the confirmation URL. This is a problem. Instead of sending the e-mail address plain text in the URL, we'll send it encrypted by a secret passphrase. (I know the attacker could still intercept the e-mail sent by the server, since e-mail are plain text, but bear with me here.) If an attacker then signs up with multiple free e-mail accounts and sees multiple URLs, each with the corresponding encrypted e-mail address, could the attacker more easily determine the passphrase used for encryption? Alternative Solution I could instead send a random number or one-way hash of their e-mail address (plus random salt). This eliminates storing the secret passphrase, but it means I need to store that random number/hash in the database. The original approach above does not require storage in the database. I'm leaning towards the the one-way-hash-stored-in-the-db, but I still would like to know the answer: does having multiple unencrypted e-mail addresses and their encrypted counterparts make it easier to determine the passphrase used?

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• Qt/C++, Problems with large QImage

  - by David Günzel

  I'm pretty new to C++/Qt and I'm trying to create an application with Visual Studio C++ and Qt (4.8.3). The application displays images using a QGraphicsView, I need to change the images at pixel level. The basic code is (simplified): QImage* img = new QImage(img_width,img_height,QImage::Format_RGB32); while(do_some_stuff) { img->setPixel(x,y,color); } QGraphicsPixmapItem* pm = new QGraphicsPixmapItem(QPixmap::fromImage(*img)); QGraphicsScene* sc = new QGraphicsScene; sc->setSceneRect(0,0,img->width(),img->height()); sc->addItem(pm); ui.graphicsView->setScene(sc); This works well for images up to around 12000x6000 pixel. The weird thing happens beyond this size. When I set img_width=16000 and img_height=8000, for example, the line img = new QImage(...) returns a null image. The image data should be around 512,000,000 bytes, so it shouldn't be too large, even on a 32 bit system. Also, my machine (Win 7 64bit, 8 GB RAM) should be capable of holding the data. I've also tried this version: uchar* imgbuf = (uchar*) malloc(img_width*img_height*4); QImage* img = new QImage(imgbuf,img_width,img_height,QImage::Format_RGB32); At first, this works. The img pointer is valid and calling img-width() for example returns the correct image width (instead of 0, in case the image pointer is null). But as soon as I call img-setPixel(), the pointer becomes null and img-width() returns 0. So what am I doing wrong? Or is there a better way of modifying large images on pixel level? Regards, David

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• Running ASP / ASP.NET markup outside of a web application (perhaps with MVC)

  - by Frank Schwieterman

  Is there a way to include some aspx/ascx markup in a DLL and use that to generate text dynamically? I really just want to pass a model instance to a view and get the produced html as a string. Similar to what you might do with an XSLT transform, except the transform input is a CLR object rather than an XML document. A second benefit is using the ASP.NET code-behind markup which is known by most team members. One way to achieve this would be to load the MVC view engine in-process and perhaps have it use an ASPX file from a resource. It seems like I could call into just the ViewEngine somehow and have it generate a ViewEngineResult. I don't know ASP.NET MVC well enough though to know what calls to make. I don't think this would be possible with classic ASP or ASP.NET as the control model is so tied to the page model, which doesn't exist in this case. Using something like SparkViewEngine in isolation would be cool too, though not as useful since other team members wouldn't know the syntax. At that point I might as well use XSLT (yes I am looking for a clever way to avoid XSLT).

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• Email as a view.

  - by Hal

  I've been in some discussion recently about where email (notifications, etc...) should be sent in an ASP.NET MVC application. My nemesis grin argues that it only makes sense that the email should be sent from the controller. I argue that an email is simply an alternate or augmented view through a different channel. Much like I would download a file as the payload of an ActionResult, the email is simply delivered through a different protocol. I've worked an extension method that allows me to do the following: <% Html.RenderEmail(model.FromAddress, model.ToAddress, model.Subject); %> which I actually include within my the view that is displayed on the screen. The beauty is that, based on convention, if I call RenderEmail from a parent view named MyView.ascx, I attempt to render the contents of a view named MyViewEmail.ascx, unless it is not found, in which case I simply email a copy of parent view. It certainly does make it testable (I still have an ISMTPService injected for testing), I wondered if anyone had any thoughts on whether or not this breaks from good practice. In use it has been extremely handy when we needed to easily send an email or modify the contents of the emailed results vs the browser rendered results. Thanks, Hal

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• MySQL Query That Can Pull the Data I am Seeking?

  - by Amy

  On the project I am working on, I am stuck with the table structure from Hades. Two things to keep in mind: I can't change the table structure right now. I'm stuck with it for the time being. The queries are dynamically generated and not hard coded. So, while I am asking for a query that can pull this data, what I am really working toward is an algorithm that will generate the query I need. Hopefully, I can explain the problem without making your eyes glaze over and your brain implode. We have an instance table that looks (simplified) along these lines: Instances InstanceID active 1 Y 2 Y 3 Y 4 N 5 Y 6 Y Then, there are multiple data tables along these lines: Table1 InstanceID field1 reference_field2 1 John 5 2 Sally NULL 3 Fred 6 4 Joe NULL Table2 InstanceID field3 5 1 6 1 Table3 InstanceID fieldID field4 5 1 Howard 5 2 James 6 2 Betty Please note that reference_field2 in Table1 contains a reference to another instance. Field3 in Table2 is a bit more complicated. It contains a fieldID for Table 3. What I need is a query that will get me a list as follows: InstanceID field1 field4 1 John Howard 2 Sally 3 Fred The problem is, in the query I currently have, I do not get Fred because there is no entry in Table3 for fieldID 1 and InstanceID 6. So, the very best list I have been able to get thus far is InstanceID field1 field4 1 John Howard 2 Sally In essence, if there is an entry in Table1 for Field 2, and there is not an entry in Table 3 that has the instanceID contained in field2 and the field ID contained in field3, I don't get the data from field1. I have looked at joins till I'm blue in the face, and I can't see a way to handle the case when table3 has no entry.

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• EAGLContext, EAGLSharegroups, RenderBuffers, FrameBuffers, oh my!

  - by quixoto

  Hi all, I'm trying to wrap my head around the OpenGL object model on iPhone OS. I'm currently rendering into a few different UIViews (build on CAEAGLayers) on the screen. I currently have each of these as using separate EAGLContext, each of which has a color renderbuffer and a framebuffer. I'm rendering similar things in them, and I'd like to share textures between these instances to save memory overhead. My current understanding is that I could use the same setup (some number of contexts, each with a FBO/RBO) but if I spawn the later ones using the EAGLShareGroup of the first one, then I can simply use the texture names (GLuints) from the first one in the later ones. Is this accurate? If this is the case, I guess the followup question is: what's the benefit to having it be a "sharegroup"? Could I just reuse the same context, and attach multiple FBOs/RBOs to that context? I think I'm struggling with the abstraction layer of a sharegroup, which seems to share "objects" (textures and other named things) but not "state" (matrices, enabled/disabled states) which are owned by the context. What's the best way to think of this? Thanks for any enlightenment!

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• Porting WebGL game to iPhone's native OpenGL?

  - by ArtPulse

  We are developing a web game that uses WebGL for the two biggest parts of it. Working with HTML / CSS was too slow and too limited, so it's off the table. Thing is, iOS does not support WebGL publicly just yet, only on iAd. It is my guess Apple will eventually support it once the security issues they and Microsoft claim it has are fixed, and looks stable enough. Problem is, if Apple does not do this by the release of the next mayor iOS version, then we will have in our hands a mobile WebGL game that does not run. 6 months of development and testing to waste. So, questions: If that was the case, how viable (regarding amount of time) is it porting the WebGL part of the game to native iPhone OpenGL? I'm afraid that porting will take longer than the development of the game itself. I saw posts on Stack Overflow (like this) that suggested, on Android, adding the OpenGL interface manually to a WebKit element. It'd be slower than native. But either way... Is this something that could be accepted in the AppStore? Apple is very restrictive with these kind of stuff... Thank you all for your time!

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• Filter of Data in Gridview logical error please using asp.net

  - by RajuBabli Abbasi

  I wanted to filter the Data in asp.net but my Data is not filtering i have some logical error So please help me for this case i will be very thanks full to those who will help me please consider my code and replay me with code if you can so please i am waiting for your replay thanks again my asp.cs file is protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { DisplayStudentInformation(); } } private void DisplayStudentInformation() { string filter = "%" + filterTextBox.Text + "%"; if (filter == String.Empty) filter = "%"; try { using (SqlDataReader reader = DAC.GetCompanyInformation(filter)) {//reader.Read(); StudentGridView.DataSource = reader; StudentGridView.DataBind(); } } catch (SqlException ex) { StatusLabel.Text = ex.Message; } } my .aspx file is asp:Table ID="Tabel" runat ="server" asp:TableRow asp:TableCell asp:Label ID="filterLabel" runat ="server" Text ="Company Name Filter:" AssociatedControlID="filterTextBox" /asp:TableCell asp:TableCell asp:TextBox ID="filterTextBox" runat="server" MaxLength ="50" /asp:TableCell asp:TableCell asp:Button ID="refreshButton" runat ="server" Text ="Filter" CausesValidation="false" / /asp:TableCell /asp:TableRow /asp:Table My DAC file is public static SqlDataReader GetCompanyInformation(string filter) { SqlDataReader reader; string sql = "SELECT * FROM Student WHERE LastName LIKE @prmLastName "; using(SqlCommand command = new SqlCommand (sql,ConnectionManager.GetConnection())) {//In ExecuteReader we pass the CommandBehavior as singleResult because we need the Single result and also passing the close connection when Datais retriev // command.Parameters.Add("@prmLastName", SqlDbType.VarChar, 25).Value = filter; command.Parameters.AddWithValue("@prmLastName", filter); reader = command.ExecuteReader(CommandBehavior.SingleResult | CommandBehavior.CloseConnection); } return reader; } Note:- When i don't use the If(!Ispostback) Condition and simply pass the DisplayStudentInformation(); method in my page load then Data can be filter but with If(!IspostBack ) condition which is also important for updating the data and for other purpose . Data can be filter . Se aim of the expert is that Filter the Data in a gridview using condition of IF(!IspostBack ) means without the removing is post back condition Filter the Data . I have been ask other about this question but no body solve this so please help me i will be very thanks full to you all ok

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• How do I exclude data from local table schema_migrations from being pushed to Heroku DB?

  - by Thierry Lam

  I was able to push my Ruby on Rails app with MySQL(local dev) to the Heroku server along with migrating my model with the command heroku rake db:migrate. I have also read the documentation on Database Import/Export. Is that doc referring to pushing actual data from my local dev DB to whichever Heroku's DB? Do I need to modify anything in the file database.yml to make it happen? I ran the following command: heroku db:push and I am getting the error: Sending data 2 tables, 3 records !!! Caught Server Exception | ETA: --:--:-- Taps Server Error: PGError ERROR: duplicate key value violates unique constraint "unique_schema_migrations" I have 2 tables, one I create for my app and the other schema_migrations. The total number of entries among the 2 tables is 3. I'm also printing the number of entries I have in the table I have created and it's showing 0. Any ideas what I might be missing or what I am doing wrong? EDIT: I figured out the above, Heroku's DB already have schema_migrations the moment I ran migrate. New question: Does anyone know how I can exclude data from a specific table from being pushed to Heroku DB. The table to exclude in this case will be schema_migrations. Not so good solution: I googled around and someone else was having the same issue. He suggested naming the schema_migrations table to zschema_migrations. In this way data from the other tables will be pushed properly until it fails on the last table. It's a pretty bad solution but will do for the time being. A better solution will be to use an existing Rails command which can reset a specific table from a database. I don't think Rake can do that.

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• Can I copy an entire Magento application to a new server?

  - by Gapton

  I am quite new to Magento and I have a case where a client has a running ecommerce website built with Magento and is running on Amazon AWS EC2 server. If I can locate the web root (/var/www/) and download everything from it (say via FTP), I should be able to boot up my virtual machine with LAMP installed, put every single files in there and it should run, right? So I did just that, and Magento is giving me an error. I am guessing there are configs somewhere that needs to be changed in order to make it work, or even a lot of paths need to be changed etc. Also databases to be replicated. What are the typical things I should get right? Database is one, and the EC2 instance uses nginx while I use plain Apache, I guess that won't work straight out of the box, and I probably will have to install nginx and a lot of other stuffs. But basically, if I setup the environment right, it should run. Is my assumption correct? Thanks for answering!

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• Should I use formal methods on my software project?

  - by Michael

  Our client wants us to build a web-based, rich internet application for gathering software requirements. Basically it's a web-based case tool that follows a specific process for getting requirements from stakeholders. I'm the project manager and we're still in the early phases of the project. I've been thinking about using formal methods to help clarify the requirements for the tool for both my client and the developers. By formal methods I mean some form of modeling, possibly something mathematically-based. Some of the things I've read about and are considering include Z (http://en.wikipedia.org/wiki/Z_notation), state machines, UML 2.0 (possibly with extensions such as OCL), Petri nets, and some coding-level stuff like contracts and pre and post conditions. Is there anything else I should consider? The developers are experienced but depending on the formalism used they may have to learn some math. I'm trying to determine whether it's worth while for me to use formal methods on this project and if so, to what extent. I know "it depends" so the most helpful answers for me is a yes/no and supporting arguments. Would you use formal methods if you were on this project?

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• iPhone UI layout debugging

  - by Cruinh

  I have this chronic issue with iPhone UI development where views sometimes seem to appear on the screen in a location different than what is reported by their frame property. Here is what I am doing to try to debug the issue: UIView *currentView = self.view; while (currentView!=nil) { NSLog(@"frame: %f,%f,%f,%f", currentView.frame.origin.x, currentView.frame.origin.y, currentView.frame.size.width, currentView.frame.size.height); currentView = currentView.superview; } I expect this should show me the coordinates and size of each element up the hierarchy from the given view to the app's root UIWindow element, with the coordinates for each element relative to its parent. However, that does not seem to be the case. In my current situation, I have a UI I'm trying to debug where every other time I rotate the device, the whole UI shifts up or down 20 pixels, yet the code block above reports exactly the same numbers every time. I tried calling the above code after as much as a second delay, but that the numbers still come out the same each time. Does anyone know a better way to inspect the screen coordinates of UI elements? If I can detect when one is wrong, I can compensate for the problem when it appears.

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• Password Cracking in 2010 and Beyond

  - by mttr

  I have looked a bit into cryptography and related matters during the last couple of days and am pretty confused by now. I have a question about password strength and am hoping that someone can clear up my confusion by sharing how they think through the following questions. I am becoming obsessed about these things, but need to spend my time otherwise :-) Let's assume we have an eight-digit password that consists of upper and lower-case alphabetic characters, numbers and common symbols. This means we have 8^96 ~= 7.2 quadrillion different possible passwords. As I understand there are at least two approaches to breaking this password. One is to try a brute-force attack where we try to guess each possible combination of characters. How many passwords can modern processors (in 2010, Core i7 Extreme for eg) guess per second (how many instructions does a single password guess take and why)? My guess would be that it takes a modern processor in the order of years to break such a password. Another approach would consist of obtaining a hash of my password as stored by operating systems and then search for collisions. Depending on the type of hash used, we might get the password a lot quicker than by the bruteforce attack. A number of questions about this: Is the assertion in the above sentence correct? How do I think about the time it takes to find collisions for MD4, MD5, etc. hashes? Where does my Snow Leopard store my password hash and what hashing algorithm does it use? And finally, regardless of the strength of file encryption using AES-128/256, the weak link is still my en/decryption password used. Even if breaking the ciphered text would take longer than the lifetime of the universe, a brute-force attack on my de/encryption password (guess password, then try to decrypt file, try next password...), might succeed a lot earlier than the end of the universe. Is that correct? I would be very grateful, if people could have mercy on me and help me think through these probably simple questions, so that I can get back to work.

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• When is onBind or onCreate called in an android service browser plugin?

  - by anselm

  I have adapted the example plugin of the android source and the browser recognises the plugin without any problem. Here is an extract of AndroidManifest.xml: <application android:icon="@drawable/icon" android:label="@string/app_name" android:debuggable="true"> <service android:name="com.domain.plugin.PluginService"> <intent-filter> <action android:name="android.webkit.PLUGIN" /> </intent-filter> </service> </application> <uses-sdk android:minSdkVersion="7" /> <uses-permission android:name="android.webkit.permission.PLUGIN"></uses-permission> The actual Service class looks like so: public class PluginService extends Service { @Override public IBinder onBind(Intent arg0) { Log.d("PluginService", "onBind"); return null; } @Override public void onCreate() { Log.d("PluginService", "onCreate"); // TODO Auto-generated method stub super.onCreate(); AssetInstaller.getInstance(this).installAssets("/data/data/com.domain.plugin"); } } The AssetInstaller code is supposed to extract some files required by the actual plugin into the /data/data/com.domain.plugin directory, however wether onBind nor onCreate are called. But I get lot's of debug trace of the actual libnpplugin.so file I'm using. So the puzzle is when and under what circumstance is the Service bound or created in case of a browser plugin. As things look the service seems to be a dummy service. Having said that, is there another intent that can be executed at installation time probably? The only solution I see right now is installing the needed files from the native plugin code instead. Any ideas? I know this is quite a tricky question ;)

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• Rhino ServiceBus: Sagas with multiple messages

  - by illdev

  I have a saga that can handle multiple messages like so: public class OrderSaga : ISaga<Order> , InitiatedBy<StartOrderSaga> , Orchestrates<CancelOrder> , Orchestrates<PaymentForOrderReceived> , Orchestrates<CheckOrderWasPaid> , Orchestrates<OrderAbandoned> , Orchestrates<CheckOrderHasBeenShipped> , Orchestrates<OrderShipped> , Orchestrates<CheckOrderHasDelayDuringShipment> , Orchestrates<OrderArrivedAtDestination> , Orchestrates<OrderCompleted> {...} but only Orchestrates<CancelOrder seems to be picked up. So I suppose (I did not find the line, but am under a strong impression this is so), that only the first Orchestrates is registered. Probably this is by design. From what I imagined a saga to be, it seems only logical that it receives many different messages, but I might be wrong. I might be wrong with my whole assumption, too :) How am I supposed to handle this? Are Sagas supposed to only handle one (in my case) a ChangeStateMessage<State or should I wire the other ConsumerOfs/Orchestrates by hand?

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