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Non-blocking TCP buffer issues.

- by Poni

Hi! I think I'm in a problem. I have two TCP apps connected to each other which use winsock I/O completion ports to send/receive data (non-blocking sockets). Everything works just fine until there's a data transfer burst. The sender starts sending incorrect/malformed data. I allocate the buffers I'm sending on the stack, and if I understand correctly, that's a wrong to do, because these buffers should remain as I sent them until I get the "write complete" notification from IOCP. Take this for example: void some_function() { char cBuff[1024]; // filling cBuff with some data WSASend(...); // sending cBuff, non-blocking mode // filling cBuff with other data WSASend(...); // again, sending cBuff // ..... and so forth! } If I understand correctly, each of these WSASend() calls should have its own unique buffer, and that buffer can be reused only when the send completes. Correct? Now, what strategies can I implement in order to maintain a big sack of such buffers, how should I handle them, how can I avoid performance penalty, etc'? And, if I am to use buffers that means I should copy the data to be sent from the source buffer to the temporary one, thus, I'd set SO_SNDBUF on each socket to zero, so the system will not re-copy what I already copied. Are you with me? Please let me know if I wasn't clear.

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How to display image within cell boundary

- by Jessy

How can I place an image within the cell boundary? I mean without taking the space of other cell? In the code below, random cells were selected to display images. One image in one cell. The problem is that, the image seems to take other cells as well. ... setPreferredSize(new Dimension(600,600)); final int ROWS = 6; final int COLS = 6; final int IMAGES = 10; setLayout(new GridBagLayout()); GridBagConstraints gc = new GridBagConstraints(); gc.weightx = 1d; gc.weighty = 1d; gc.insets = new Insets(0, 0, 0, 0);//top, left, bottom, and right gc.fill = GridBagConstraints.NONE; JLabel[][] label = new JLabel[ROWS][COLS]; Random rand = new Random(); // fill the panel with labels for (int i=0;i<IMAGES;i++){ ImageIcon icon = createImageIcon("myImage.jpg"); int r, c; do{ //pick random cell which is empty to avoid overlap image in the same cell r = (int)Math.floor(Math.random() * ROWS); c = (int)Math.floor(Math.random() * COLS); } while (label[r][c]!=null); //scale the image int x = rand.nextInt(20)+30; int y = rand.nextInt(20)+30; Image image = icon.getImage().getScaledInstance(x,y, Image.SCALE_SMOOTH); icon.setImage(image); JLabel lbl = new JLabel(icon); gc.gridx = r; gc.gridy = c; add(lbl, gc); //add image to the cell label[r][c] = lbl; }

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How to display image within cell boundary

- by Jessy

How can I place an image within the cell boundary? I mean without taking the space of other cell? In the code below, random cells were selected to display images. One image in one cell. The problem is that, the image seems to take other cells as well. ... setPreferredSize(new Dimension(600,600)); final int ROWS = 6; final int COLS = 6; final int IMAGES = 10; setLayout(new GridBagLayout()); GridBagConstraints gc = new GridBagConstraints(); gc.weightx = 1d; gc.weighty = 1d; gc.insets = new Insets(0, 0, 0, 0);//top, left, bottom, and right gc.fill = GridBagConstraints.NONE; JLabel[][] label = new JLabel[ROWS][COLS]; Random rand = new Random(); // fill the panel with labels for (int i=0;i<IMAGES;i++){ ImageIcon icon = createImageIcon("myImage.jpg"); int r, c; do{ //pick random cell which is empty to avoid overlap image in the same cell r = (int)Math.floor(Math.random() * ROWS); c = (int)Math.floor(Math.random() * COLS); } while (label[r][c]!=null); //scale the image int x = rand.nextInt(20)+30; int y = rand.nextInt(20)+30; Image image = icon.getImage().getScaledInstance(x,y, Image.SCALE_SMOOTH); icon.setImage(image); JLabel lbl = new JLabel(icon); gc.gridx = r; gc.gridy = c; add(lbl, gc); //add image to the cell label[r][c] = lbl; }

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How to disable the drop down function of combo box on certain conditions?

- by Angeline Aarthi

Hi, I have a combo box in my application. I also have a variable called "Status". I want the combo box to be enabled only when the value of the Status variable is 5 or 6. Otherwise, I should not be able to change the value in the combo box. It should have the previous value only.. I had written a click event to disable the combo box. But even though the combo box is disabled, I get the drop down list of the combo box, and If I select some othe value in the drop down,it changes..Only after that it gets disabled.. How to avoid this? I want the drop down function itself to be disabled. This is the code I have written. Someone guide me. <mx:FormItem label="Review Status:" width="100%" horizontalAlign="right"> <mx:HBox> <mx:Label width="30"/> <mx:ComboBox id="reviewStatus" dataProvider="{Status}" width="150" click="onStatusChange(event)"/> </mx:HBox> Action Script part: private function onStatusChange(event:Event):void { var i:int; for(i=0;i<defectDetails.length;i++) { var defStatusId:String=defectDetails.getItemAt(i).DefectStatusId; if(defStatusId=="5"){ reviewStatus.enabled=true; } else if(defStatusId=="6"){ reviewStatus.enabled=true; } else{ reviewStatus.enabled=false; //reviewStatus.selectedItem.label="Review"; reviewStatus.toolTip="Status can be changed only if Defect Status is Verified or Deferred."; //Alert.show("Status can be changed only if defect status is verified or deferred"); } } } If I use Change event also, for the first time the value is changed. Only after that,the combo box is disabled. How to retain the same value and disable the combo box when the status is not 5 or 6?

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Returning from dll (Asynchronous sockets)

- by Juha

I am trying to do a simple http-server in (c++) dll-file that I can use from managed (C#) application with P/Invoke. I was trying to do this with asynchronous functions (WSAAsyncSelect() and stuff), so that I could manage server by calling functions inside dll whenever needed and after that it would return to my main program. Now I'm not sure if that is even possible. It seems that "main function" in dll, the function that starts the server, has to include message loop or something and since it's a loop, it doesn't return from dll ever. Could I somehow do this message stuff in my managed application and call some function in dll when there is something to do? Or is it even possible to do this stuff in one thred? I would really like to avoid all concurrency stuff. The dll looks now basicly the same as here, main function is the one that I call from managed C# program and would like to return to there after calling the function. http://www.winsocketdotnetworkprogramming.com/winsock2programming/winsock2advancediomethod5b.html I'm quite noob in windows programming, and never even heard of this message-queue or message-loop.

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MVC view engine that can render classic ASP?

- by David Lively

I'm about to start integrating ASP.NET MVC into an existing 200k+ line classic ASP application. Rewriting the existing code (which runs an entire business, not just the public-facing website) is not an option. The existing ASP 3.0 pages are quite nicely structured (given what was available when this model was put into place nearly 15 years ago), like so:      <h1>page name</h1> <p>some content goes here</p> <p>some content goes here</p> <p>.....</p> <h2>Today's Top Forum Posts</h2> <%=forum_top_posts(1)%>  ... or somesuch. Some pages will include function and sub definitions, but for the most part these exist in include files. I'm wondering how difficult it would be to write an MVC view engine that could render classic ASP, preferably using the existing ASP.DLL. In that case, I could replace  with <%= Html.RenderPartial("lib/user"); %> as I gradually move existing pages from ASP to ASP.NET. Since the existing formatting and library includes are used very extensively, they must be maintained. I'd like to avoid having to maintain two separate versions. I know the ideal way to go about this would be to simply start a new app and say to hell with the ASP code, however, that simply ain't gonna happen. Ideas?

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Rails form protection questions, hidden field

- by user284194

I have a live rails website and I want to have a form with a lot of fields on it. I have set up validations and allowed formatting for every field. I've tested it quite a bit and it seems to catch anything I throw at it. I think it's almost ready to go live, but I want to quadruple check if there's anything else I should do to protect it. My site has a low volume of visitors, but I want it to be a safe as possible. I'd like to avoid using a captcha if I can. I've read that you can use a hidden field to protect forms against bots. Do people recommend this instead of using a captcha, or even using it with a captcha? my form is really standard: <% form_for(@entry) do |f| %> ... <%= f.submit 'Create' %> <% end %> Any suggestions or code samples would be greatly appreciated.

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Bundle a Python app as a single file to support add-ons or extensions?

- by Brandon Craig Rhodes

There are several utilities — all with different procedures, limitations, and target operating systems — for getting a Python package and all of its dependencies and turning them into a single binary program that is easy to ship to customers: http://wiki.python.org/moin/Freeze http://www.pyinstaller.org/ http://www.py2exe.org/ http://svn.pythonmac.org/py2app/py2app/trunk/doc/index.html My situation goes one step further: third-party developers will be wanting to write plug-ins, extensions, or add-ons for my application. It is, of course, a daunting question how users on platforms like Windows would most easily install plugins or addons in such a way that my app can easily discover that they have been installed. But beyond that basic question is another: how can a third-party developer bundle their extension with whatever libraries the extension itself needs (which might be binary modules, like lxml) in such a way that the plugin's dependencies become available for import at the same time that the plugin becomes available. How can this be approached? Will my application need its own plug-in area on disk and its own plug-in registry to make this tractable? Or are there general mechanisms, that I could avoid writing myself, that would allow an app that is distributed as a single executable to look around and find plugins that are also installed as single files?

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CSS3 Gradients and border-radius leading to extraneous background in webkit

- by iamfriendly

Hello all, After my 1st question with relation to CSS3 gradients in which I was recreating an 'inner glow' I've now got to the point where I'm not so happy with the way in which webkit renders the effect. Basically, if you give an element a background colour and apply a border radius to it, webkit lets the background colour "bleed" out to fill the surrounding box (making it look a bit awful) To reproduce the undesirable effect, try something like the following section#featured footer p a { color: rgb(255,255,255); text-shadow: 1px 1px 1px rgba(0,0,0,0.6); text-decoration: none; padding: 5px 10px; border-radius: 15px; -moz-border-radius: 15px; -webkit-border-radius: 15px; background: rgb(98,99,100); -moz-box-shadow: inset 0 0 8px rgba(0,0,0, 0.25); -webkit-box-shadow: inset 0 0 8px rgba(0,0,0, 0.25); } You can see an example of this here: http://iamfriendly.clients.friendlygp.com/ Apparently this appears to be a Windows-only problem, so for those on a Mac, here's a screenshot: (Check the 'carry on reading' button) You'll notice that in Safari/Chrome (the latest available public downloads as well as the latest nightlies as far as I can tell), you get a rather ugly background colour bleed. However, in Firefox, you should be able to see what I'm after. If you're in Internet Explorer, woe betide you. Does anyone know of a technique which will allow me to produce the 'correct' effect? Is there a CSS Property which I've missed that tells webkit to only have the background within the border-radius'd part of the containing box. I could potentially use an image, but I'm really trying to avoid it. Naturally, as we're dealing with CSS3 and the landscape is continually changing, I might just have to 'lump' it and revert to an image. However, if anyone can suggest an alternative I would be very much appreciative!

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Knowing the selections made on a 'multichooser' box in a mechanical turk hit (using Command Line Too

- by gveda

Hi All, I am new to Amazon Mechanical Turk, and wanted to create a hit with a qualification task. I am using the command line tools interface. One of the questions in my qualification task involves users selecting a number of options. I use a 'multichooser' selection type. Now I want to grade the responses based on the selections, where each selection has a different score. So for example, s1 has a score of 5, s2 of 10, s3 of 6, and so on. If the user selects s1 and s3, he/she gets a score of 11. Unfortunately, doing something like the following does not work: <AnswerOption> <SelectionIdentifier>s1</SelectionIdentifier> <AnswerScore>5</AnswerScore> </AnswerOption> <AnswerOption> <SelectionIdentifier>s2</SelectionIdentifier> <AnswerScore>10</AnswerScore> </AnswerOption> <AnswerOption> <SelectionIdentifier>s3</SelectionIdentifier> <AnswerScore>6</AnswerScore> </AnswerOption> If I do this, when I select multiple things, I get a score of 0. If I select only one option, say s1, then I get the appropriate score. Can you please help me on how to go about this? I could ask the same question 5 times with the same options, but then users might choose the same answer multiple times - something I wish to avoid. Thanks! Gaurav

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How to assign .net membership roles to individual database records

- by mdresser

I'm developing a system where we want to restrict the availability of information displayed to users based on their roles. e.g. I have a tabled called EventType (ID, EventTypeDescription) which contains the following records: 1, 'Basic Event' 2, 'Intermediate Event' 3, 'Admin Event' What I need to achieve is to filter the records returned based on the username (and hence role) of the logged-in user. e.g if an advanced user is logged in they will see all the event types, if the standard user is logged in they will only see the basic event type etc. Ideally id like to do this in a way which can be easily extended to other tables as necessary. So I'd like to avoid simply adding a 'Roles' field to each table where the data is user context sensitive. One idea I'm thinking of is to create some kind of permissions table like: PermissionsTable ( ID, Aspnet_RoleId, TableName, PrimaryKeyValue ) this has the drawback of using this is obviously having to use the table name to switch which table to join onto. Edit: In the absence of any better suggestions, I'm going to go with the last idea I mentioned, but instead of having a TableName field, I'm going to normalise the TableName out to it's own table as follows: TableNames ( ID, TableName ) UserPermissionsTable ( ID, Aspnet_UserId, TableID, PrimaryKeyValue )

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ASP.NET MVC 2: How to write this Linq SQL as a Dynamic Query (using strings)?

- by Dr. Zim

Skip to the "specific question" as needed. Some background: The scenario: I have a set of products with a "drill down" filter (Query Object) populated with DDLs. Each progressive DDL selection will further limit the product list as well as what options are left for the DDLs. For example, selecting a hammer out of tools limits the Product Sizes to only show hammer sizes. Current setup: I created a query object, sent it to a repository, and fed each option to a SQL "table valued function" where null values represent "get all products". I consider this a good effort, but far from DDD acceptable. I want to avoid any "programming" in SQL, hopefully doing everything with a repository. Comments on this topic would be appreciated. Specific question: How would I rewrite this query as a Dynamic Query? A link to something like 101 Linq Examples would be fantastic, but with a Dynamic Query scope. I really want to pass to this method the field in quotes "" for which I want a list of options and how many products have that option. (from p in db.Products group p by p.ProductSize into g select new Category { PropertyType = g.Key, Count = g.Count() }).Distinct(); Each DDL option will have "The selection (21)" where the (21) is the quantity of products that have that attribute. Upon selecting an option, all other remaining DDLs will update with the remaining options and counts.

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JOAL with JNLPAppletLauncher Problem

- by user347445

Hi, I am developing a Java Applet that makes use of JOAL. In order to avoid annoying dialogues I wanted to load JOAL with the JNLPAppletLauncher as it is shown on https://jogl-demos.dev.java.net/applettest-joal.html Unfortunately with this approach I get this exception: JNLPAppletLauncher.loadLibrary("joal_native") loading: C:\Users\Barbara\AppData\Local\Temp\jnlp-applet\jln7379734545861869319\jln1640167325490042232\joal_native.dll Exception in thread "AWT-EventQueue-2" java.lang.RuntimeException: Can not get proc address for method "alcCaptureCloseDevice": Couldn't set value of field "_addressof_alcCaptureCloseDevice" in class net.java.games.joal.impl.ALCProcAddressTable at com.sun.gluegen.runtime.ProcAddressHelper.resetProcAddressTable(ProcAddressHelper.java:113) at net.java.games.joal.impl.ALProcAddressLookup.resetALCProcAddressTable(ALProcAddressLookup.java:109) at net.java.games.joal.impl.ALCImpl.alcOpenDevice(ALCImpl.java:341) at net.java.games.joal.util.ALut.alutInit(ALut.java:69) at demos.devmaster.lesson1.SingleStaticSource.initialize(SingleStaticSource.java:194) at demos.devmaster.lesson1.SingleStaticSource.access$000(SingleStaticSource.java:57) at demos.devmaster.lesson1.SingleStaticSource$1.actionPerformed(SingleStaticSource.java:79) at javax.swing.AbstractButton.fireActionPerformed(Unknown Source) at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.setPressed(Unknown Source) at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source) at java.awt.Component.processMouseEvent(Unknown Source) at javax.swing.JComponent.processMouseEvent(Unknown Source) at java.awt.Component.processEvent(Unknown Source) at java.awt.Container.processEvent(Unknown Source) at java.awt.Component.dispatchEventImpl(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.run(Unknown Source) Caused by: java.lang.RuntimeException: Unable to find and load OpenAL library at net.java.games.joal.impl.ALProcAddressLookup$DynamicLookup.dynamicLookupFunction(ALProcAddressLookup.java:66) at com.sun.gluegen.runtime.ProcAddressHelper.resetProcAddressTable(ProcAddressHelper.java:106) ... 30 more I am using Firefox 3.6.3, Java 1.6._017 and am on a Windows 7 Machine. I also tried this on another computer with Windows XP and on one with Linux, always with the same result, so it does not seem to be specific for my computer. I also get the same result for IE8. Any ideas how I could fix this? Thank you very much.

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Delphi 2009 dbExpress and Interbase: Unicode migration steps and risks?

- by mjustin

Currently, our database uses Win1252 as the only character encoding. We will have to support Unicode in the database tables soon, which means we have to perform this migration for four databases and around 80 Delphi applications which run in-house in a 24/7 environment. Are there recommendations for database migrations to UTF-8 (or UNICODE_FSS) for Delphi applications? Some questions listed below. Many thanks in advance for your answers! are there tools which help with the migration of the existing databases (sizes between 250 MB and 2 GB, no Blob fields), by dumping the data, recreating the database with UNICODE_FSS or UTF-8, and loading the data back? are there known problems with Delphi 2009, dbExpress and Interbase 7.5 related to Unicode character sets? would you recommend to upgrade the databases to Interbase 2009 first? (This upgrade is planned but does not have a high priority) can we simply migrate the database and Delphi will handle the Unicode character sets automatically, or will we have to change all character field types in every Datamodule (dfm and source code) too? which strategy would you recommend to work on the migration in parallel with the normal development and maintenance of the existing application? The application runs in-house so development and database administration is done internally. Update: one problem I found now is that there are two different persistent field types for Unicode and non Unicode character fields. For the existing database, dbExpress creates TStringField objects. For the Unicode database fields, dbExpress creates (or expects!) TWideStringField objects. This looks like a lot of work lies ahead. While we could try to avoid persistent fields (and add calculated fields at run time), Of course we would prefer a solution which does not require so many changes in existing units and DFM files.

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How can I serialize and communicate ActiveRecord instances across identical Rails apps?

- by Blaine LaFreniere

The main idea is that I have several worker instances of a Rails app, and then a main aggregate I want to do something like this with the following pseudo pseudo-code posts = Post.all.to_json( :include => { :comments => { :include => :blah } }) # send data to another, identical, exactly the same Rails app # ... # Fast forward to the separate but identical Rails app: # ... # remote_posts is the posts results from the first Rails app posts = JSON.parse(remote_posts) posts.each do |post| p = Post.new p = post p.save end I'm shying away from Active Resource because I have thousands of records to create, which would mean thousands of requests for each record. Unless there is a way to do it all in one request with Active Resource that is simple, I'd like to avoid it. Format doesn't matter. Whatever makes it convenient. The IDs don't need to be sent, because the other app will just be creating records and assigning new IDs in the "aggregate" system. The hierarchy would need to be preserved (E.g. "Hey other Rails app, I have genres, and each genre has an artist, and each artist has an album, and each album has songs" etc.)

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Java File IO Compendium

- by Warren Taylor

I've worked in and around Java for nigh on a decade, but have managed to ever avoid doing serious work with files. Mostly I've written database driven applications, but occasionally, even those require some file io. Since I do it so rarely, I end up googling around for quite some time to figure out the exact incantation that Java requires to read a file into a byte[], char[], String or whatever I need at the time. For a 'once and for all' list, I'd like to see all of the usual ways to get data from a file into Java, or vice versa. There will be a fair bit of overlap, but the point is to define all of the subtle different variants that are out there. For example: Read/Write a text file from/to a single String. Read a text file line by line. Read/Write a binary file from/to a single byte[]. Read a binary file into a byte[] of size x, one chunk at a time. The goal is to show concise ways to do each of these. Samples do not need to handle missing files or other errors, as that is generally domain specific. Feel free to suggest more IO tasks that are somewhat common and I have neglected to mention.

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Switching from Sourcesafe - What to look for in a product

- by asp316

We're looking to move off of sourcesafe and on to a more robust source control system for our .Net apps. We're also looking for scripted/automated deployments. I'm a .Net developer (web and winforms). However, most of our development staff is RPG for the IBM iSeries and the devs use Aldon's LMI for source control and deployment. Our manager would prefer to stick with Aldon so all of our products are in the same system. However, I don't have experience with Aldon's products on the .Net side. I've used TFS and Subversion with Tortoise a bit, but not enough to recommend one or the other, especially in comparison to Aldon's product. Does anybody have experience with Aldon's products? If so, thoughts please? Also, other than the obvious things source control systems do, are there things I should avoid or are there must haves? I'm open to any system. A bit of background, I'm the only .Net dev in our company but I let operations do the deployments. I do want the ability to support concurrent checkouts if we hire a new dev.

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Don't fire onfocus when selecting text?

- by Casey Hope

I'm writing a JavaScript chatting application, but I'm running into a minor problem. Here is the HTML structure: <div id="chat"> <div id="messages"></div> <textarea></textarea> </div> When the user clicks/focuses on the chat box, I want the textbox to be automatically focused. I have this onfocus handler on the chat box: chat.onfocus = function () { textarea.focus(); } This works, but the problem is that in Firefox, this makes it impossible to select text in the messages div, since when you try to click on it, the focus shifts to the textarea. How can I avoid this problem? (Semi-related issues: In Chrome, textarea.focus() doesn't seem to shift the keyboard focus to the textarea; it only highlights the box. IE8 does not seem to respond to the onfocus at all when clicking, even if it tabindex is set. Any idea why?)

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Firefox: Can I use a relative path in the BASE tag?

- by Aaron Digulla

I have a little web project where I have many pages and an index/ToC file. The toc file is at the root of my project in toc.html. The pages are spread over a couple of subdirectories and include the toc with an iframe. The project doesn't need a web server, so I can create the HTML in a directory and browse it in my browser. The problem is that I'm running into XSS issues when JavaScript from the toc.html wants to call a function in a page (violation of the same origin policy). So I added base tags in the header with a relative URL to the directory in which toc.html. This works for Konqueror but in Firefox, I have to use absolute paths or the toc won't even display :( Here is an example: <?xml version='1.0' encoding='utf-8' ?> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <base href="../" target="_top" /> <title>Project 1</title> </head> <body> <iframe class="toc" frameborder="0" src="toc.html"> </iframe> </body> </html> This is file is in a subdirectory page. Firefox won't even load it, saying that it can't find page/toc.html. Is there a workaround? I would really like to avoid absolute paths in my export to keep it the same everywhere (locally and when I upload it on the web server later).

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Duck type testing with C# 4 for dynamic objects.

- by Tracker1

I'm wanting to have a simple duck typing example in C# using dynamic objects. It would seem to me, that a dynamic object should have HasValue/HasProperty/HasMethod methods with a single string parameter for the name of the value, property, or method you are looking for before trying to run against it. I'm trying to avoid try/catch blocks, and deeper reflection if possible. It just seems to be a common practice for duck typing in dynamic languages (JS, Ruby, Python etc.) that is to test for a property/method before trying to use it, then falling back to a default, or throwing a controlled exception. The example below is basically what I want to accomplish. If the methods described above don't exist, does anyone have premade extension methods for dynamic that will do this? Example: In JavaScript I can test for a method on an object fairly easily. //JavaScript function quack(duck) { if (duck && typeof duck.quack === "function") { return duck.quack(); } return null; //nothing to return, not a duck } How would I do the same in C#? //C# 4 dynamic Quack(dynamic duck) { //how do I test that the duck is not null, //and has a quack method? //if it doesn't quack, return null }

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Resizing video best practices (frame size)

- by undefined

I have read the following which is from Best Practices for Encoding Video with the VP6 Codec on the Adobe website here - http://www.adobe.com/devnet/flash/articles/encoding_video_print.html. It is talking about common video ratios (320x240, 640x480) Although these ratios are standard, and should be used to avoid distorting the video, the size of the encoded video is not set in stone. The original web video sizes used heights and widths that were evenly divisible by 16. This was mandatory for many early codecs. Although this is not necessary for modern codecs, you should stick to even heights and widths. What do they mean by 'even heights and widths'. I am thinking about encoding my video at 400x300 to make it slightly bigger, this is still 4x3 format but should I just stick at 320x240 and resize it on the screen? Clearly there are benefits to this in terms of storage size and delivery costs. In some places on my site I want to show the video at 400x300 but in others I want it to play full screen so this is why I am wondering if a larger original size (400x300) will give better results when blown up. Any thoughts?

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recursively implementing 'minimum number of coins' in python

- by user5198

This problem is same as asked in here. Given a list of coins, their values (c1, c2, c3, ... cj, ...), and the total sum i. Find the minimum number of coins the sum of which is i (we can use as many coins of one type as we want), or report that it's not possible to select coins in such a way that they sum up to S. I"m just introduced to dynamic programming yesterday and I tried to make a code for it. # Optimal substructure: C[i] = 1 + min_j(C[i-cj]) cdict = {} def C(i, coins): if i <= 0: return 0 if i in cdict: return cdict[i] else: answer = 1 + min([C(i - cj, coins) for cj in coins]) cdict[i] = answer return answer Here, C[i] is the optimal solution for amount of money 'i'. And available coins are {c1, c2, ... , cj, ...} for the program, I've increased the recursion limit to avoid maximum recursion depth exceeded error. But, this program gives the right answer only someones and when a solution is not possible, it doesn't indicate that. What is wrong with my code and how to correct it?

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SecurityNegotiationException in WCF Service Hosted on IIS

- by Ram

Hi, I have hosted a WCF service on IIS. The configuration file is as follows <?xml version="1.0"?>  <configuration> <configSections> <sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"> <sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"> <section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/> <sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"> <section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="Everywhere" /> <section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /> <section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /> <section name="roleService" type="System.Web.Configuration.ScriptingRoleServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /> </sectionGroup> </sectionGroup> </sectionGroup> </configSections> <appSettings/> <connectionStrings/> <system.web>  <compilation debug="false"> <assemblies> <add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/> <add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> </assemblies> </compilation>  <authentication mode="Windows" />  <pages> <controls> <add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> </controls> </pages> <httpHandlers> <remove verb="*" path="*.asmx"/> <add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false"/> </httpHandlers> <httpModules> <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> </httpModules> </system.web> <system.codedom> <compilers> <compiler language="c#;cs;csharp" extension=".cs" warningLevel="4" type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"> <providerOption name="CompilerVersion" value="v3.5"/> <providerOption name="WarnAsError" value="false"/> </compiler> </compilers> </system.codedom> <system.web.extensions> <scripting> <webServices>    </webServices>  </scripting> </system.web.extensions>  <system.webServer> <validation validateIntegratedModeConfiguration="false"/> <modules> <add name="ScriptModule" preCondition="integratedMode" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> </modules> <handlers> <remove name="WebServiceHandlerFactory-Integrated"/> <add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add name="ScriptHandlerFactoryAppServices" verb="*" path="*_AppService.axd" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add name="ScriptResource" preCondition="integratedMode" verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /> </handlers> </system.webServer> <system.serviceModel> <services> <service name="IISTest2.Service1" behaviorConfiguration="IISTest2.Service1Behavior">  <endpoint address="" binding="wsHttpBinding" contract="IISTest2.IService1">  <identity> <dns value="localhost"/> </identity> </endpoint> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/> </service> </services> <behaviors> <serviceBehaviors> <behavior name="IISTest2.Service1Behavior">  <serviceMetadata httpGetEnabled="true"/>  <serviceDebug includeExceptionDetailInFaults="false"/> </behavior> </serviceBehaviors> </behaviors> </system.serviceModel> </configuration> The client configuration file is as follows <?xml version="1.0" encoding="utf-8" ?> <configuration> <system.serviceModel> <bindings> <wsHttpBinding> <binding name="WSHttpBinding_IService1" closeTimeout="00:01:00" openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00" bypassProxyOnLocal="false" transactionFlow="false" hostNameComparisonMode="StrongWildcard" maxBufferPoolSize="524288" maxReceivedMessageSize="65536" messageEncoding="Text" textEncoding="utf-8" useDefaultWebProxy="true" allowCookies="false"> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384" maxBytesPerRead="4096" maxNameTableCharCount="16384" /> <reliableSession ordered="true" inactivityTimeout="00:10:00" enabled="false" /> <security mode="Message"> <transport clientCredentialType="Windows" proxyCredentialType="None" realm="" /> <message clientCredentialType="Windows" negotiateServiceCredential="true" algorithmSuite="Default" establishSecurityContext="true" /> </security> </binding> </wsHttpBinding> </bindings> <client> <endpoint address="http://yyy.zzz.xxx.net/IISTest2/Service1.svc" binding="wsHttpBinding" bindingConfiguration="WSHttpBinding_IService1" contract="ServTest.IService1" name="WSHttpBinding_IService1"> <identity> <dns value="localhost" /> </identity> </endpoint> </client> </system.serviceModel> </configuration> When I tried to access the service from client application, I got SecurityNegotiationException and details are Secure channel cannot be opened because security negotiation with the remote endpoint has failed. This may be due to absent or incorrectly specified EndpointIdentity in the EndpointAddress used to create the channel. Please verify the EndpointIdentity specified or implied by the EndpointAddress correctly identifies the remote endpoint. If I host the service on ASP .NET Dev server, it work well but if I host on IIS above mentioned error occurs. Thanks, Ram

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Java UTF-8 to ASCII conversion with supplements

- by bozo

Hi, we are accepting all sorts of national characters in UTF-8 string on the input, and we need to convert them to ASCII string on the output for some legacy use. (we don't accept Chinese and Japanese chars, only European languages) We have a small utility to get rid of all the diacritics: public static final String toBaseCharacters(final String sText) { if (sText == null || sText.length() == 0) return sText; final char[] chars = sText.toCharArray(); final int iSize = chars.length; final StringBuilder sb = new StringBuilder(iSize); for (int i = 0; i < iSize; i++) { String sLetter = new String(new char[] { chars[i] }); sLetter = Normalizer.normalize(sLetter, Normalizer.Form.NFC); try { byte[] bLetter = sLetter.getBytes("UTF-8"); sb.append((char) bLetter[0]); } catch (UnsupportedEncodingException e) { } } return sb.toString(); } The question is how to replace all the german sharp s (ß, Ð, d) and other characters that get through the above normalization method, with their supplements (in case of ß, supplement would probably be "ss" and in case od Ð supplement would be either "D" or "Dj"). Is there some simple way to do it, without million of .replaceAll() calls? So for example: Ðonardan = Djonardan, Blaß = Blass and so on. We can replace all "problematic" chars with empty space, but would like to avoid this to make the output as similar to the input as possible. Thank you for your answers, Bozo

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how to atomically claim a row or resource using UPDATE in mysql

- by Igor

i have a table of resources (lets say cars) which i want to claim atomically. if there's a limit of one resource per one user, i can do the following trick: UPDATE cars SET user = 'bob' WHERE user IS NULL LIMIT 1 SELECT * FROM cars WHERE user IS bob that way, i claim the resource atomically and then i can see which row i just claimed. this doesn't work when 'bob' can claim multiple cars. i realize i can get a list of cars already claimed by bob, claim another one, and then SELECT again to see what's changed, but that feels hackish. What I'm wondering is, is there some way to see which rows i just updated with my last UPDATE? failing that, is there some other trick to atomically claiming a row? i really want to avoid using SERIALIZABLE isolation level. If I do something like this: 1 SELECT id FROM cars WHERE user IS NULL 2 <here, my PHP or whatever picks a car id> 3 UPDATE cars SET user = 'bob' WHERE id = <the one i picked> would REPEATABLE READ be sufficient here? in other words, could i be guaranteed that some other transactions won't claim the row my software has picked during step 2?

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