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• WinQual: Why would WER not accept code-signing certificates?

  - by Ian Boyd

  In 2005 i tried to establish a WinQual account with Microsoft, so i could pick up our (if any) crash dump files submitted automatically through Windows Error Reporting (WER). i was not allowed to have my crash dumps, because i don't have a Verisign certificate. Instead i have a cheaper one, generated by a Verisign subsidiary: Thawte. The method in which you join is: you digitally sign a sample exe they provide. This proves that you are the same signer that signed apps that they got crash dumps from in the wild. Cryptographically, the private key is needed to generate a digital signature on an executable. Only the holder of that private key can create a signature with for the matching public key. It doesn't matter who generated that private key. That includes certificates that are generated from: self-signing Wells Fargo DigiCert SecureTrust Trustware QuoVadis GoDaddy Entrust Cybertrust GeoTrust GlobalSign Comodo Thawte Verisign Yet Microsof's WinQual only accepts digital certificates generated by Verisign. Not even Verisign's subsidiaries are good enough (Thawte). Can anyone think of any technical, legal or ethical reason why Microsoft doesn't want to accept code-signing certificates? The WinQual site says: Why Is a Digital Certificate Required for Winqual Membership? A digital certificate helps protect your company from individuals who seek to impersonate members of your staff or who would otherwise commit acts of fraud against your company. Using a digital certificate enables proof of an identity for a user or an organization. Is somehow a Thawte digital certificate not secure? Two years later, i sent a reminder notice to WinQual that i've been waiting to be able to get at my crash dumps. The response from WinQual team was: Hello, Thanks for the reminder. We have notified the appropriate people that this is still a request. In 2008 i asked this question in a Microsoft support forum, and the response was: We are only setup to accept VeriSign Certificates at this point. We have not had an overwhelming demand to support other types of certificates. What can it possibly mean to not be "setup" to accept other kinds of certificates? If the thumbprint of the key that signed the WinQual.exe test app is the same as the thumbprint that signed the executable who's crash dump you got in the wild: it is proven - they are my crash dumps, give them to me. And it's not like there's a special API to check if a Verisign digital signature is valid, as opposed to all other digital signatures. A valid signature is valid no matter who generated the key. Microsoft is free to not trust the signer, but that's not the same as identity. So that is my question, can anyone think of any practical reason why WinQual isn't setup to support digital signatures? One person theorized that the answer is that they're just lazy: Not that I know but I would assume that the team running the winQual system is a live team and not a dev team - as in, personality and skillset geared towards maintenance of existing systems. I could be wrong though. They don't want to do work to change it. But can anyone think of anything that would need to be changed? It's the same logic no matter what generated the key: "does the thumbprint match". What am i missing?

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• Is SHA-1 secure for password storage?

  - by Tgr

  Some people throw around remarks like "SHA-1 is broken" a lot, so I'm trying to understand what exactly that means. Let's assume I have a database of SHA-1 password hashes, and an attacker whith a state of the art SHA-1 breaking algorithm and a botnet with 100,000 machines gets access to it. (Having control over 100k home computers would mean they can do about 10^15 operations per second.) How much time would they need to find out the password of any one user? find out the password of a given user? find out the password of all users? find a way to log in as one of the users? find a way to log in as a specific user? How does that change if the passwords are salted? Does the method of salting (prefix, postfix, both, or something more complicated like xor-ing) matter? Here is my current understanding, after some googling. Please correct in the answers if I misunderstood something. If there is no salt, a rainbow attack will immediately find all passwords (except extremely long ones). If there is a sufficiently long random salt, the most effective way to find out the passwords is a brute force or dictionary attack. Neither collision nor preimage attacks are any help in finding out the actual password, so cryptographic attacks against SHA-1 are no help here. It doesn't even matter much what algorithm is used - one could even use MD5 or MD4 and the passwords would be just as safe (there is a slight difference because computing a SHA-1 hash is slower). To evaluate how safe "just as safe" is, let's assume that a single sha1 run takes 1000 operations and passwords contain uppercase, lowercase and digits (that is, 60 characters). That means the attacker can test 1015*60*60*24 / 1000 ~= 1017 potential password a day. For a brute force attack, that would mean testing all passwords up to 9 characters in 3 hours, up to 10 characters in a week, up to 11 characters in a year. (It takes 60 times as much for every additional character.) A dictionary attack is much, much faster (even an attacker with a single computer could pull it off in hours), but only finds weak passwords. To log in as a user, the attacker does not need to find out the exact password; it is enough to find a string that results in the same hash. This is called a first preimage attack. As far as I could find, there are no preimage attacks against SHA-1. (A bruteforce attack would take 2160 operations, which means our theoretical attacker would need 1030 years to pull it off. Limits of theoretical possibility are around 260 operations, at which the attack would take a few years.) There are preimage attacks against reduced versions of SHA-1 with negligible effect (for the reduced SHA-1 which uses 44 steps instead of 80, attack time is down from 2160 operations to 2157). There are collision attacks against SHA-1 which are well within theoretical possibility (the best I found brings the time down from 280 to 252), but those are useless against password hashes, even without salting. In short, storing passwords with SHA-1 seems perfectly safe. Did I miss something?

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• Help to solve "Robbery Problem"

  - by peiska

  Hello, Can anybody help me with this problem in C or Java? The problem is taken from here: http://acm.pku.edu.cn/JudgeOnline/problem?id=1104 Inspector Robstop is very angry. Last night, a bank has been robbed and the robber has not been caught. And this happened already for the third time this year, even though he did everything in his power to stop the robber: as quickly as possible, all roads leading out of the city were blocked, making it impossible for the robber to escape. Then, the inspector asked all the people in the city to watch out for the robber, but the only messages he got were of the form "We don't see him." But this time, he has had enough! Inspector Robstop decides to analyze how the robber could have escaped. To do that, he asks you to write a program which takes all the information the inspector could get about the robber in order to find out where the robber has been at which time. Coincidentally, the city in which the bank was robbed has a rectangular shape. The roads leaving the city are blocked for a certain period of time t, and during that time, several observations of the form "The robber isn't in the rectangle Ri at time ti" are reported. Assuming that the robber can move at most one unit per time step, your program must try to find the exact position of the robber at each time step. Input The input contains the description of several robberies. The first line of each description consists of three numbers W, H, t (1 <= W,H,t <= 100) where W is the width, H the height of the city and t is the time during which the city is locked. The next contains a single integer n (0 <= n <= 100), the number of messages the inspector received. The next n lines (one for each of the messages) consist of five integers ti, Li, Ti, Ri, Bi each. The integer ti is the time at which the observation has been made (1 <= ti <= t), and Li, Ti, Ri, Bi are the left, top, right and bottom respectively of the (rectangular) area which has been observed. (1 <= Li <= Ri <= W, 1 <= Ti <= Bi <= H; the point (1, 1) is the upper left hand corner, and (W, H) is the lower right hand corner of the city.) The messages mean that the robber was not in the given rectangle at time ti. The input is terminated by a test case starting with W = H = t = 0. This case should not be processed. Output For each robbery, first output the line "Robbery #k:", where k is the number of the robbery. Then, there are three possibilities: If it is impossible that the robber is still in the city considering the messages, output the line "The robber has escaped." In all other cases, assume that the robber really is in the city. Output one line of the form "Time step : The robber has been at x,y." for each time step, in which the exact location can be deduced. (x and y are the column resp. row of the robber in time step .) Output these lines ordered by time . If nothing can be deduced, output the line "Nothing known." and hope that the inspector will not get even more angry. Output a blank line after each processed case.

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• swfobject weird behavior

  - by David

  Hi All, I'm using swfobject to embed my flash. It's doing weird things. I've created a simple textfield using FlexBuilder. It's an AS3 project, which extends Sprite. I've set its width to be 640 and height to 450. Then, in the swfobject parameters of the page, I've also set 640 x 450. I've made the background nice and red and ugly so you can see it. :) http://www.brighttext.com/flash/TextFieldSetFormat.html It seems to be the right dimensions. BUT I've got a textfield which is supposed to be almost the same size and height. This runs fine in FlexBuilder (is the right size) but is all messed up once I add swfobject Can anyone see what is happening? EDIT NOTE: I just looked at it and it looks ok. But then I refreshed the page and the textfield is postage-stamp size (again -- this is the original behavior I saw.) It's now looking OK in firefox but not in IE8. Flash is supposed to look the same in all browsers !!?? AS3 code: package { import flash.display.Sprite; import flash.text.TextField; import flash.text.TextFormat; import flash.text.Font; [SWF(width="640", height="450", backgroundColor="#FFFFFF", frameRate="30")] public class TextFieldSetFormat extends Sprite { [Embed(source='C:/WINDOWS/Fonts/ArialBD.TTF', fontWeight = 'bold', fontName='ArialBold')] [Embed(source='C:/WINDOWS/Fonts/Arial.TTF', fontWeight = 'regular', fontName='Arial')] public function TextFieldSetFormat() { var tf2:TextFormat = new TextFormat(); tf2.size = 16; tf2.font = "Arial"; Font.registerFont(_VerdanaFontBold); Font.registerFont(_VerdanaFont); var pad:Number = 10; var brightTextField:TextField = new TextField; brightTextField.backgroundColor = 0xDDF3B2; brightTextField.background = true; brightTextField.embedFonts = true; brightTextField.border = true; brightTextField.defaultTextFormat = tf2; brightTextField.wordWrap = true; brightTextField.multiline = true; brightTextField.width = stage.stageWidth - (4 * pad); brightTextField.height = stage.stageHeight - (3 * pad); brightTextField.x = 2*pad; brightTextField.y = 2*pad; brightTextField.text = "Dear Senators, I have become concerned over the idea that some in the Senate will oppose the public option because of a group of wild-eyed, overbearing but misinformed ideologues. These people mistakenly equate insurance reform with Socialism and call our first African-American President unprintable epithets. This is unacceptable. The public option is the choice of more than 70% of Americans, a majority of the House and a great many opinion leaders. Passing insurance reform without a public option persists the current broken system. I am aware that many Senators would prefer to pass a reform bill with bipartisan support. But we cannot allow this critical debate to be hijacked by extremists or corporate profiteers. Thank you, and I look forward to hearing from you."; addChild(brightTextField); } } }

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• Chaining CSS classes in IE6 - Trying to find a jQuery solution?

  - by Mike Baxter

  Right, perhaps I ask the impossible? I consider myself fairly new to Javscript and jQuery, but that being said, I have written some fairly complex code recently so I am definitely getting there... however I am now possed with a rather interesting issue at my current freelance contract. The previous web coder has taken a Grid-960 approach to the HTML and as a result has used chained classes to style many of the elements. The example below is typical of what can be found in the code: <div class='blocks four-col-1 orange highlight'>Some content</div> And in the css there will be different declarations for: (not actual css... but close enough) .blocks {margin-right:10px;} .orange {background-image:url(someimage.jpg);} .highlight {font-weight:bold;} .four-col-1 {width:300px;} and to make matters worse... this is in the CSS: .blocks.orange.highlight {background-colour:#dd00ff;} Anyone not familiar with this particular bug can read more on it here: http://www.ryanbrill.com/archives/multiple-classes-in-ie/ it is very real and very annoying. Without wanting to go into the merrits of not chaining classes (I told them this, but it is no longer feasible to change their approach... 100 hand coded pages into a 150 page website, no CMS... sigh) and without the luxury of being able to change the way these blocks are styled... can anyone advise me on the complexity and benefits between any of my below proposed approaches or possible other options that would adequately solve this problem. Potential Solution 1 Using conditional comments I am considering loading a jquery script only for IE6 that: Reads the class of all divs in a certain section of the page and pushes to an array creates empty boxes off screen with only one of the classes applied at a time Reads the applied CSS values for each box Re-applies these styles to the individual box, somehow bearing in mind the order in which they are called and overwriting conflicting instructions as required Potential Solution 2 read the class of all divs in a certain section of the page and push to an array Scan the document for links to style sheets Ajax grab the stylesheets and traverse looking for matching names to those in class array Apply styles as needed Potential Solution 3 Create an IE6 only stylesheet containing the exact style to be applied as a unique name (ie: class='blocks orange highlight' becomes class='blocks-orange-highlight') Traverse the document in IE6 and convert all spaces in class declarations to hyphens and reapply classes based on new style name Summary: Solution 1 allows the people at this company to apply any styles in the future and the script will adjust as needed. However it does not allow for the chained style to be added, only the individual style... it is also processor intensive and time consuming, but also the most likely to be converted into a plugin that could be used the world over Solution 2 is a potential nightmare to code. But again will allow for an endless number of updates without breaking Solution 3 will require someone at the companty to hardcode the new styles every time they make a change, and if they don't, IE6 will break. Ironically the site, whilst needing to conform to IE6 in a limited manner, does not need to run wihtout javascript (they've made the call... have JS or go away), so consider all jQuery and JS solutions to be 'game on'. Did I mention how much i hate IE6? Anyway... any thoughts or comments would be appreciated. I will continue to develop my own solution and if I discover one that can be turned into a jQuery plugin I will post it here in the comments. Regards, Mike.

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• A format for storing personal contacts in a database

  - by Gart

  I'm thinking of the best way to store personal contacts in a database for a business application. The traditional and straightforward approach would be to create a table with columns for each element, i.e. Name, Telephone Number, Job title, Address, etc... However, there are known industry standards for this kind of data, like for example vCard, or hCard, or vCard-RDF/XML or even Windows Contacts XML Schema. Utilizing an standard format would offer some benefits, like inter-operablilty with other systems. But how can I decide which method to use? The requirements are mainly to store the data. Search and ordering queries are highly unlikely but possible. The volume of the data is 100,000 records at maximum. My database engine supports native XML columns. I have been thinking to use some XML-based format to store the personal contacts. Then it will be possible to utilize XML indexes on this data, if searching and ordering is needed. Is this a good approach? Which contacts format and schema would you recommend for this? Edited after first answers Here is why I think the straightforward approach is bad. This is due to the nature of this kind of data - it is not that simple. The personal contacts it is not well-structured data, it may be called semi-structured. Each contact may have different data fields, maybe even such fields which I cannot anticipate. In my opinion, each piece of this data should be treated as important information, i.e. no piece of data could be discarded just because there was no relevant column in the database. If we took it further, assuming that no data may be lost, then we could create a big text column named Comment or Description or Other and put there everything which cannot be fitted well into table columns. But then again - the data would lose structure - this might be bad. If we wanted structured data then - according to the database design principles - the data should be decomposed into entities, and relations should be established between the entities. But this adds complexity - there are just too many entities, and lots of design desicions should be made, like "How do we store Address? Personal Name? Phone number? How do we encode home phone numbers and mobile phone numbers? How about other contact info?.." The relations between entities are complex and multiple, and each relation is a table in the database. Each relation needs to be documented in the design papers. That is a lot of work to do. But it is possible to avoid the complexity entirely - just document that the data is stored according to such and such standard schema, period. Then anybody who would be reading that document should easily understand what it was all about. Finally, this is all about using an industry standard. The standard is, hopefully, designed by some clever people who anticipated and described the structure of personal contacts information much better than I ever could. Why should we all reinvent the wheel?? It's much easier to use a standard schema. The problem is, there are just too many standards - it's not easy to decide which one to use!

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• How to create Large resumable download from a secured location .NET

  - by Kelvin H

  I need to preface I'm not a .NET coder at all, but to get partial functionality, I modified a technet chunkedfilefetch.aspx script that uses chunked Data Reading and writing Streamed method of doing file transfer, to get me half-way. iStream = New System.IO.FileStream(path, System.IO.FileMode.Open, _ IO.FileAccess.Read, IO.FileShare.Read) dataToRead = iStream.Length Response.ContentType = "application/octet-stream" Response.AddHeader("Content-Length", file.Length.ToString()) Response.AddHeader("Content-Disposition", "attachment; filename=" & filedownload) ' Read and send the file 16,000 bytes at a time. ' While dataToRead 0 If Response.IsClientConnected Then length = iStream.Read(buffer, 0, 16000) Response.OutputStream.Write(buffer, 0, length) Response.Flush() ReDim buffer(16000) ' Clear the buffer ' dataToRead = dataToRead - length Else ' Prevent infinite loop if user disconnects ' dataToRead = -1 End If End While This works great on files up to 2GB and is fully functioning now.. But only one problem it doesn't allow for resume. I took the original code called it fetch.aspx and pass an orderNUM through the URL. fetch.aspx&ordernum=xxxxxxx It then reads the filename/location from the database occording to the ordernumber, and chunks it out from a secured location NOT under the webroot. I need a way to make this resumable, by the nature of the internet and large files people always get disconnected and would like to resume where they left off. But any resumable articles i've read, assume the file is within the webroot.. ie. http://www.devx.com/dotnet/Article/22533/1954 Great article and works well, but I need to stream from a secured location. I'm not a .NET coder at all, at best i can do a bit of coldfusion, if anyone could help me modify a handler to do this, i would really appreciate it. Requirements: I Have a working fetch.aspx script that functions well and uses the above code snippet as a base for the streamed downloading. Download files are large 600MB and are stored in a secured location outside of the webroot. Users click on the fetch.aspx to start the download, and would therefore be clicking it again if it was to fail. If the ext is a .ASPX and the file being sent is a AVI, clicking on it would completely bypass an IHTTP handler mapped to .AVI ext, so this confuses me From what I understand the browser will read and match etag value and file modified date to determine they are talking about the same file, then a subsequent accept-range is exchanged between the browser and IIS. Since this dialog happens with IIS, we need to use a handler to intercept and respond accordingly, but clicking on the link would send it to an ASPX file which the handeler needs to be on an AVI fiel.. Also confusing me. If there is a way to request the initial HTTP request header containing etag, accept-range into the normal .ASPX file, i could read those values and if the accept-range and etag exist, start chunking at that byte value somehow? but I couldn't find a way to transfer the http request headers since they seem to get lost at the IIS level. OrderNum which is passed in the URL string is unique and could be used as the ETag Response.AddHeader("ETag", request("ordernum")) Files need to be resumable and chunked out due to size. File extensions are .AVI so a handler could be written around it. IIS 6.0 Web Server Any help would really be appreciated, i've been reading and reading and downloading code, but none of the examples given meet my situation with the original file being streamed from outside of the webroot. Please help me get a handle on these httphandlers :)

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• being able to solve google code jam problem sets

  - by JPro

  This is not a homework question, but rather my intention to know if this is what it takes to learn programming. I keep loggin into TopCoder not to actually participate but to get the basic understand of how the problems are solved. But to my knowledge I don't understand what the problem is and how to translate the problem into an algorithm that can solve it. Just now I happen to look at ACM ICPC 2010 World Finals which is being held in china. The teams were given problem sets and one of them is this: Given at most 100 points on a plan with distinct x-coordinates, find the shortest cycle that passes through each point exactly once, goes from the leftmost point always to the right until it reaches the rightmost point, then goes always to the left until it gets back to the leftmost point. Additionally, two points are given such that the the path from left to right contains the first point, and the path from right to left contains the second point. This seems to be a very simple DP: after processing the last k points, and with the first path ending in point a and the second path ending in point b, what is the smallest total length to achieve that? This is O(n^2) states, transitions in O(n). We deal with the two special points by forcing the first path to contain the first one, and the second path contain the second one. Now I have no idea what I am supposed to solve after reading the problem set. and there's an other one from google code jam: Problem In a big, square room there are two point light sources: one is red and the other is green. There are also n circular pillars. Light travels in straight lines and is absorbed by walls and pillars. The pillars therefore cast shadows: they do not let light through. There are places in the room where no light reaches (black), where only one of the two light sources reaches (red or green), and places where both lights reach (yellow). Compute the total area of each of the four colors in the room. Do not include the area of the pillars. Input * One line containing the number of test cases, T. Each test case contains, in order: * One line containing the coordinates x, y of the red light source. * One line containing the coordinates x, y of the green light source. * One line containing the number of pillars n. * n lines describing the pillars. Each contains 3 numbers x, y, r. The pillar is a disk with the center (x, y) and radius r. The room is the square described by 0 = x, y = 100. Pillars, room walls and light sources are all disjoint, they do not overlap or touch. Output For each test case, output: Case #X: black area red area green area yellow area Is it required that people who program should be should be able to solve these type of problems? I would apprecite if anyone can help me interpret the google code jam problem set as I wish to participate in this years Code Jam to see if I can do anthing or not. Thanks.

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• Sending emails in web applications

  - by Denise

  Hi everyone, I'm looking for some opinions here, I'm building a web application which has the fairly standard functionality of: Register for an account by filling out a form and submitting it. Receive an email with a confirmation code link Click the link to confirm the new account and log in When you send emails from your web application, it's often (usually) the case that there will be some change to the persistence layer. For example: A new user registers for an account on your site - the new user is created in the database and an email is sent to them with a confirmation link A user assigns a bug or issue to someone else - the issue is updated and email notifications are sent. How you send these emails can be critical to the success of your application. How you send them depends on how important it is that the intended recipient receives the email. We'll look at the following four strategies in relation to the case where the mail server is down, using example 1. TRANSACTIONAL & SYNCHRONOUS The sending of the email fails and the user is shown an error message saying that their account could not be created. The application will appear to be slow and unresponsive as the application waits for the connection timeout. The account is not created in the database because the transaction is rolled back. TRANSACTIONAL & ASYNCHRONOUS The transactional definition here refers to sending the email to a JMS queue or saving it in a database table for another background process to pick up and send. The user account is created in the database, the email is sent to a JMS queue for processing later. The transaction is successful and committed. The user is shown a message saying that their account was created and to check their email for a confirmation link. It's possible in this case that the email is never sent due to some other error, however the user is told that the email has been sent to them. There may be some delay in getting the email sent to the user if application support has to be called in to diagnose the email problem. NON-TRANSACTIONAL & SYNCHRONOUS The user is created in the database, but the application gets a timeout error when it tries to send the email with the confirmation link. The user is shown an error message saying that there was an error. The application is slow and unresponsive as it waits for the connection timeout When the mail server comes back to life and the user tries to register again, they are told their account already exists but has not been confirmed and are given the option of having the email re-sent to them. NON-TRANSACTIONAL & ASYNCHRONOUS The only difference between this and transactional & asynchronous is that if there is an error sending the email to the JMS queue or saving it in the database, the user account is still created but the email is never sent until the user attempts to register again. What I'd like to know is what have other people done here? Can you recommend any other solutions other than the 4 I've mentioned above? What's a reasonable way of approaching this problem? I don't want to over-engineer a system that's dealing with the (hopefully) rare situation where my mail server goes down! The simplest thing to do is to code it synchronously, but are there any other pitfalls to this approach? I guess I'm wondering if there's a best practice, I couldn't find much out there by googling.

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• Nightmare: Upgrading Tomcat 5.5 to 6.0

  - by pavanlimo

  I'm trying to upgrade a perfectly running embedded Tomcat 5.5 to Tomcat 6.0. I understand that all I need to do is replace Tomcat 5.5 jars with 6.0. That's what I did. So I replaced the following jars: catalina-5.0.28.jar catalina-5.5.9.jar catalina-optional-5.5.9.jar commons-el.jar commons-modeler-1.1.0.jar jasper-compiler-jdt.jar jasper-compiler.jar jasper-runtime.jar jmx-5.0.28.jar jsp-api-2.0.jar naming-factory.jar naming-resources.jar servlet-api-2.4.jar servlets-default.jar tomcat-coyote.jar tomcat-http.jar tomcat-util.jar with: annotations-api.jar catalina.jar jasper.jar tomcat-dbcp.jar catalina-ant.jar el-api.jar jsp-api.jar tomcat-i18n-es.jar catalina-ha.jar jasper-el.jar servlet-api.jar tomcat-i18n-fr.jar catalina-tribes.jar jasper-jdt.jar tomcat-coyote.jar tomcat-i18n-ja.jar tomcat-juli.jar As soon as I start the server, I get the following message in the logs at INFO level: INFO: Starting Servlet Engine: Apache Tomcat/6.0.29 Dec 31, 2010 6:04:18 AM org.apache.catalina.loader.WebappClassLoader validateJarFile INFO: validateJarFile(/usr/local/blah/blue/./WEB-INF/lib/servlet-api.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class Based on the this explanation, I need to remove a jar file which has a conflicting Servlet.class. I swear to God, there is no other conflicting jar file, I grepped system wide for Servlet.class, it matched only servlet-api.jar. I also downloaded javaee.jar and replaced it by servlet-api.jar, to same avail. Having tried lot of these stuff, I did not have much to look upto, so set the tomcat logging level to ALL. In the log I could see that it is trying to check for Servlet.class in each and every jar it is loading until it finds servlet-api.jar and throws "jar not loaded" message as soon as it finds servlet-api.jar. See below: FINE: Checking for javax/servlet/Servlet.class Jan 2, 2011 7:39:33 AM org.apache.catalina.loader.WebappLoader setRepositories FINE: Deploy JAR /WEB-INF/lib/servlet-api.jar to /usr/local/blah/blue/./WEB-INF/lib/servlet-api.jar Jan 2, 2011 7:39:33 AM org.apache.catalina.loader.WebappClassLoader addJar FINE: addJar(/WEB-INF/lib/servlet-api.jar) Jan 2, 2011 7:39:33 AM org.apache.catalina.loader.WebappClassLoader validateJarFile FINE: Checking for javax/servlet/Servlet.class Jan 2, 2011 7:39:33 AM org.apache.catalina.loader.WebappClassLoader validateJarFile INFO: validateJarFile(/usr/local/blah/blue/./WEB-INF/lib/servlet-api.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class Jan 2, 2011 7:39:33 AM org.apache.catalina.loader.WebappLoader setRepositories Please note however, that Tomcat starts successfully! And as soon as I hit the URL on the browser, I get blank page(this may be in my case only, I guess 'cuz of my web.xml, sorta different from most. Other people on the internet have got Error 404 instead.) with following log statements(at finest level) Jan 2, 2011 9:40:01 AM org.apache.catalina.connector.CoyoteAdapter parseSessionCookiesId FINE: Requested cookie session id is 0FBA716E3F9B0147C3AF7ABAE3B1C27B Jan 2, 2011 9:40:01 AM org.apache.catalina.authenticator.AuthenticatorBase invoke FINE: Security checking request GET /login.jsp Jan 2, 2011 9:40:01 AM org.apache.catalina.realm.RealmBase findSecurityConstraints FINE: Checking constraint 'SecurityConstraint[protected]' against GET /login.jsp --> false Jan 2, 2011 9:40:01 AM org.apache.catalina.realm.RealmBase findSecurityConstraints FINE: Checking constraint 'SecurityConstraint[protected]' against GET /login.jsp --> false Jan 2, 2011 9:40:01 AM org.apache.catalina.realm.RealmBase findSecurityConstraints FINE: Checking constraint 'SecurityConstraint[protected]' against GET /login.jsp --> false Jan 2, 2011 9:40:01 AM org.apache.catalina.realm.RealmBase findSecurityConstraints FINE: Checking constraint 'SecurityConstraint[protected]' against GET /login.jsp --> false Jan 2, 2011 9:40:01 AM org.apache.catalina.realm.RealmBase findSecurityConstraints FINE: No applicable constraint located Jan 2, 2011 9:40:01 AM org.apache.catalina.authenticator.AuthenticatorBase invoke FINE: Not subject to any constraint Jan 2, 2011 9:40:01 AM org.apache.catalina.core.StandardWrapper allocate FINEST: Returning non-STM instance I'm not sure if the above log message is important, but I'm for all-out disclosure here. One interesting thing though, I manually created a dummy jsp file containing only "helloooo" just outside WEB-INF folder(no security constraints for this file). This file was accessible and could be displayed. But, all my jsp's and classes are inside WEB-INF(ofcourse). Sick and tired of this issue, please help me solve it. I've already spent 20-24 hours on this unsuccessfully. Any pointers directions hints leads?

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• What is "elegant" code?

  - by Breton

  I see a lot of lip service and talk about the most "elegant" way to do this or that. I think if you spend enough time programming you begin to obtain a sort of intuitive feel for what it is we call "elegance". But I'm curious. Even if we can look at a bit of code, and say instinctively "That's elegant", or "That's messy", I wonder if any of us really understands what that means. Is there a precise definition for this "elegance" we keep referring to? If there is, what is it? Now, what I mean by a precise definition, is a series of statements which can be used to derive questions about a peice of code, or a program as a whole, and determine objectively, or as objectively as possible, whether that code is "elegant" or not. May I assert, that perhaps no such definition exists, and it's all just personal preference. In this case, I ask you a slightly different question: Is there a better word for "elegance", or a better set of attributes to use for judging code quality that is perhaps more objective than merely appealing to individual intuition and taste? Perhaps code quality is a matter of taste, and the answer to both of my questions is "no". But I can't help but feel that we could be doing better than just expressing wishy washy feelings about our code quality. For example, user interface design is something that to a broad range of people looks for all the world like a field of study that oughtta be 100% subjective matter of taste. But this is shockingly and brutally not the case, and there are in fact many objective measures that can be applied to a user interface to determine its quality. A series of tests could be written to give a definitive and repeatable score to user interface quality. (See GOMS, for instance). Now, okay. is Elegance simply "code quality" or is it something more? Is it something that can be measured? Or is it a matter of taste? Does our profession have room for taste? Maybe I'm asking the wrong questions altogether. Help me out here. Bonus Round If there is such a thing as elegance in code, and that concept is useful, do you think that justifies classifying the field of programming as an "Art" capital A, or merely a "craft". Or is it just an engineering field populated by a bunch of wishful thinking humans? Consider this question in the light of your thoughts about the elegance question. Please note that there is a distinction between code which is considered "art" in itself, and code that was written merely in the service of creating an artful program. When I ask this question, I ask if the code itself justifies calling programming an art. Bounty Note I liked the answers to this question so much, I think I'd like to make a photographic essay book from it. Released as a free PDF, and published on some kind of on demand printing service of course, such as "zazz" or "tiggle" or "printley" or something . I'd like some more answers, please!

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• Incremental PCA

  - by smichak

  Hi, Lately, I've been looking into an implementation of an incremental PCA algorithm in python - I couldn't find something that would meet my needs so I did some reading and implemented an algorithm I found in some paper. Here is the module's code - the relevant paper on which it is based is mentioned in the module's documentation. I would appreciate any feedback from people who are interested in this. Micha #!/usr/bin/env python """ Incremental PCA calculation module. Based on P.Hall, D. Marshall and R. Martin "Incremental Eigenalysis for Classification" which appeared in British Machine Vision Conference, volume 1, pages 286-295, September 1998. Principal components are updated sequentially as new observations are introduced. Each new observation (x) is projected on the eigenspace spanned by the current principal components (U) and the residual vector (r = x - U(U.T*x)) is used as a new principal component (U' = [U r]). The new principal components are then rotated by a rotation matrix (R) whose columns are the eigenvectors of the transformed covariance matrix (D=U'.T*C*U) to yield p + 1 principal components. From those, only the first p are selected. """ __author__ = "Micha Kalfon" import numpy as np _ZERO_THRESHOLD = 1e-9 # Everything below this is zero class IPCA(object): """Incremental PCA calculation object. General Parameters: m - Number of variables per observation n - Number of observations p - Dimension to which the data should be reduced """ def __init__(self, m, p): """Creates an incremental PCA object for m-dimensional observations in order to reduce them to a p-dimensional subspace. @param m: Number of variables per observation. @param p: Number of principle components. @return: An IPCA object. """ self._m = float(m) self._n = 0.0 self._p = float(p) self._mean = np.matrix(np.zeros((m , 1), dtype=np.float64)) self._covariance = np.matrix(np.zeros((m, m), dtype=np.float64)) self._eigenvectors = np.matrix(np.zeros((m, p), dtype=np.float64)) self._eigenvalues = np.matrix(np.zeros((1, p), dtype=np.float64)) def update(self, x): """Updates with a new observation vector x. @param x: Next observation as a column vector (m x 1). """ m = self._m n = self._n p = self._p mean = self._mean C = self._covariance U = self._eigenvectors E = self._eigenvalues if type(x) is not np.matrix or x.shape != (m, 1): raise TypeError('Input is not a matrix (%d, 1)' % int(m)) # Update covariance matrix and mean vector and centralize input around # new mean oldmean = mean mean = (n*mean + x) / (n + 1.0) C = (n*C + x*x.T + n*oldmean*oldmean.T - (n+1)*mean*mean.T) / (n + 1.0) x -= mean # Project new input on current p-dimensional subspace and calculate # the normalized residual vector g = U.T*x r = x - (U*g) r = (r / np.linalg.norm(r)) if not _is_zero(r) else np.zeros_like(r) # Extend the transformation matrix with the residual vector and find # the rotation matrix by solving the eigenproblem DR=RE U = np.concatenate((U, r), 1) D = U.T*C*U (E, R) = np.linalg.eigh(D) # Sort eigenvalues and eigenvectors from largest to smallest to get the # rotation matrix R sorter = list(reversed(E.argsort(0))) E = E[sorter] R = R[:,sorter] # Apply the rotation matrix U = U*R # Select only p largest eigenvectors and values and update state self._n += 1.0 self._mean = mean self._covariance = C self._eigenvectors = U[:, 0:p] self._eigenvalues = E[0:p] @property def components(self): """Returns a matrix with the current principal components as columns. """ return self._eigenvectors @property def variances(self): """Returns a list with the appropriate variance along each principal component. """ return self._eigenvalues def _is_zero(x): """Return a boolean indicating whether the given vector is a zero vector up to a threshold. """ return np.fabs(x).min() < _ZERO_THRESHOLD if __name__ == '__main__': import sys def pca_svd(X): X = X - X.mean(0).repeat(X.shape[0], 0) [_, _, V] = np.linalg.svd(X) return V N = 1000 obs = np.matrix([np.random.normal(size=10) for _ in xrange(N)]) V = pca_svd(obs) print V[0:2] pca = IPCA(obs.shape[1], 2) for i in xrange(obs.shape[0]): x = obs[i,:].transpose() pca.update(x) U = pca.components print U

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• Qt, MSVC, and /Zc:wchar_t- == I want to blow up the world

  - by Noah Roberts

  So Qt is compiled with /Zc:wchar_t- on windows. What this means is that instead of wchar_t being a typedef for some internal type (__wchar_t I think) it becomes a typedef for unsigned short. The really cool thing about this is that the default for MSVC is the opposite, which of course means that the libraries you're using are likely compiled with wchar_t being a different type than Qt's wchar_t. This doesn't become an issue of course until you try to use something like std::wstring in your code; especially when one or more libraries have functions that accept it as parameters. What effectively happens is that your code happily compiles but then fails to link because it's looking for definitions using std::wstring<unsigned short...> but they only contain definitions expecting std::wstring<__wchar_t...> (or whatever). So I did some web searching and ran into this link: http://bugreports.qt.nokia.com/browse/QTBUG-6345 Based on the statement by Thiago Macieira, "Sorry, we will not support building Qt like this," I've been worried that fixing Qt to work like everything else might cause some problem and have been trying to avoid it. We recompiled all of our support libraries with the /Zc:wchar_t- flag and have been fairly content with that until a couple days ago when we started trying to port over (we're in the process of switching from Wx to Qt) some serialization code. Because of how win32 works, and because Wx just wraps win32, we've been using std::wstring to represent string data with the intent of making our product as i18n ready as possible. We did some testing and Wx did not work with multibyte characters when trying to print special stuff (even not so special stuff like the degree symbol was an issue). I'm not so sure that Qt has this problem since QString isn't just a wrapper to the underlying _TCHAR type but is a Unicode monster of some sort. At any rate, the serialization library in boost has compiled parts. We've attempted to recompile boost with /Zc:wchar_t- but so far our attempts to tell bjam to do this have gone unheeded. We're at an impasse. From where I'm sitting I have three options: Recompile Qt and hope it works with /Zc:wchar_t. There's some evidence around the web that others have done this but I have no way of predicting what will happen. All attempts to ask Qt people on forums and such have gone unanswered. Hell, even in that very bug report someone asks why and it just sat there for a year. Keep fighting with bjam until it listens. Right now I've got someone under me doing that and I have more experience fighting with things to get what I want but I do have to admit to getting rather tired of it. I'm also concerned that I'll KEEP running into this issue just because Qt wants to be a c**t. Stop using wchar_t for anything. Unfortunately my i18n experience is pretty much 0 but it seems to me that I just need to find the right to/from function in QString (it has a BUNCH) to encode the Unicode into 8-bytes and visa-versa. UTF8 functions look promising but I really want to be sure that no data will be lost if someone from Zimbabfuckegypt starts writing in their own language and the documentation in QString frightens me a little into thinking that could happen. Of course, I could always run into some library that insists I use wchar_t and then I'm back to 1 or 2 but I rather doubt that would happen. So, what's my question... Which of these options is my best bet? Is Qt going to eventually cause me to gouge out my own eyes because I decided to compile it with /Zc:wchar_t anyway? What's the magic incantation to get boost to build with /Zc:wchar_t- and will THAT cause permanent mental damage? Can I get away with just using the standard 8-bit (well, 'common' anyway) character classes and be i18n compliant/ready? How do other Qt developers deal with this mess?

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• Character-encoding problem spring

  - by aelshereay

  Hi All, I am stuck in a big problem with encoding in my website! I use spring 3, tomcat 6, and mysql db. I want to support German and Czech along with English in my website, I created all the JSPs as UTF-8 files, and in each jsp I include the following: <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> I created messages.properties (the default which is Czech), messages_de.properties, and messages_en.properties. And all of them are saved as UTF-8 files. I added the following to web.xml: <filter> <filter-name>encodingFilter</filter-name> <filterclass> org.springframework.web.filter.CharacterEncodingFilter</filterclass> <init-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> <init-param> <param-name>forceEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <locale-encoding-mapping-list> <locale-encoding-mapping> <locale>en</locale> <encoding>UTF-8</encoding> </locale-encoding-mapping> <locale-encoding-mapping> <locale>cz</locale> <encoding>UTF-8</encoding> </locale-encoding-mapping> <locale-encoding-mapping> <locale>de</locale> <encoding>UTF-8</encoding> </locale-encoding-mapping> </locale-encoding-mapping-list> <filter-mapping> <filter-name>encodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> And add the following to my applicationContext.xml: <bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource" p:basenames="messages"/> <!-- Declare the Interceptor --> <mvc:interceptors> <bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor" p:paramName="locale" /> </mvc:interceptors> <!-- Declare the Resolver --> <bean id="localeResolver" class="org.springframework.web.servlet.i18n.SessionLocaleResolver" /> I set the useBodyEncodingForURI attribute to true in the element of server.xml under: %CATALINA_HOME%/conf, also another time tried to add URIEncoding="UTF-8" instead. I created all the tables and fields with charset [utf8] and collection [utf8_general_ci] The encoding in my browser is UTF-8 (BTW, I have IE8 and Firefox 3.6.3) When I open the MYSQL Query browser and insert manually Czech or German data, it's being inserted correctly, and displayed correctly in my app as well. So, here's the list of problems I have: By default the messages.properties (Czech) should load, instead the messages_en.properties loads by default. In the web form, when I enter Czech data, then click submit, in the Controller I print out the data in the console before to save it to db, what's being printed is not correct having strange chars, and this is the exact data that saves to db. I don't know where's the mistake! Why can't I get it working although I did what people did and worked for them! don't know.. Please help me, I am stuck in this crappy problem since days, and it drives me crazy! Thank you in advance.

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• Keyboard for programming

  - by exhuma

  This may seem a bit a tangential topic. It's not directly related to actual code, but is important for our line of work nevertheless. Over the years, I've switched keyboards a few times. All of them had slightly different key layouts. And I'm not talking about the language/locale layout, but the physical layout! Why not the locale layout? Well, quite frankly, that's easy to change via software. I personally have a German keyboard but have it set to the UK layout. Why? It's quite hard to find different layouts in the shops where I live. Even ordering is not always easy in the shops. So that leaves me with Internet shops. But I prefer to "test" my keyboards before buying. The most notable changes are: Mangled "Home Key Block" I've seen this first on a Logitech keyboard, but it may have originated elsewhere. Shape of the "Enter" key I've seen three different cases so far: Two lines high, wider at the top Two lines high, wider at the bottom One line high Shape of the Backspace button I've seen two types so far: One "character" wide Two "characters" wide OS Keys For Macs, you have the Option and Command buttons, for Windows you have the Windows and Context Menu buttons. Cherry even produced a Linux keyboard once (unfortunately I cannot find many details except news results). I assume a dedicated Linux keyboard would sport a Compose key and had the SysRq always labelled as well (note that some standard layouts do this already). Obviously... .. all these differences entail that some keys have to be moved around the board a lot. Which means, if you are used to one and have to work on another one, you happen to hit the wrong keys quite often. As it happens, this is much more annoying for programmers as it is for people who write texts. Mainly because the keys which are moved around are special character keys, often used in programming. Often these hardware layouts depend also indirectly on where you buy the keyboards. Honestly, I haven't seen a keyboard with a one-line "Enter" key in Germany, nor Luxembourg. I may just have missed it but that's how it looks to me at least. A survey I've seen some attempts at surveys in the style "which keyboard is best for programming". But they all - in my opinion - are not using comparable sets. So I was wondering if it was possible to concoct a survey taking the above criteria into account. But ignoring key dimensions that one would be a bit overkill I guess ;) From what I can see there are the following types of physical layout: Backspace: 2-characters wide Enter: 2-Lines, wider top Backspace: 2-characters wide Enter: 1-Line Backspace: 1-character wide Enter: 2-Lines, wider bottom Then there are the other possible permutations (home-key block, os-keys), which in total makes for quite a large list of categories. Now, I wonder... Would anyone be interested in such a survey? I personally would. Because I am looking for the perfect fit for me. If yes, then I could really use the help of anyone here to propose some models to include in the survey. Once I have some models for each category (I'd say at least 3 per category) I could go ahead and write up a survey, put it on-line and let the it collect data for a while. What do you think?

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• How to eliminate NULL fields in TSQL

  - by salvationishere

  I am developing a TSQL query in SSMS 2008 R2. I am trying to develop this query to identify one record / client. Because some of these values are NULL, I am currently doing LEFT JOINS on most of the tables. But the problem with the LEFT JOINs is that now I get 1 record for some clients. But if I change this to INNER JOINs then some clients are excluded entirely because they have NULL values for these columns. How do I limit the query result to just one record / client regardless of NULL values? And if there are non-NULL values then I want it to choose the record with non-NULL values. Here is some of my current output: group_profile_id profile_name license_number is_accepting is_accepting_placement managing_office region vendor_name vendor_id applicant_type Office Address status_description Cert Date2 race ethnicity_desc religion 9CD932F1-6BE1-4F80-AB81-0CE32C565BCF Atreides Foster Home 1 Atreides1 1 Yes Manchester, NH Gulf Atlantic Atreides1 00000007 Treatment Foster Home 4042 Arrakis Avenue, Springfield, VT 05156 Open/Re-opened 2011-06-01 00:00:00.000 NULL NULL NULL DCE354D5-A7CC-409F-B5A3-89BF664B7718 Averitte, Leon and Sandra 00000044 1 Yes Birmingham, AL Gulf Atlantic AL Averitte, Leon and Sandra 00000044 Treatment Foster Home 3816 5th Avenue, Bessemer, AL 35020, (205)482-4307 Open/Re-opened 2011-08-05 00:00:00.000 NULL NULL NULL DCE354D5-A7CC-409F-B5A3-89BF664B7718 Averitte, Leon and Sandra 00000044 1 Yes Birmingham, AL Gulf Atlantic AL Averitte, Leon and Sandra 00000044 Treatment Foster Home 3816 5th Avenue, Bessemer, AL 35020, (205)482-4307 Open/Re-opened 2011-08-05 00:00:00.000 Caucasian/White Non Hispanic NULL AD02A43C-6F38-4F35-8C9E-E12422690BFB Bass, Matthew and Sarah 00000076 1 Yes Jacks on, MS Central Gulf Coast MS Bass, Matthew and Sarah 00000076 Treatment Foster Home 506 Eagelwood Drive, Florence, MS 39073, (601)665-7169 Open/Re-opened 2011-04-01 00:00:00.000 NULL NULL NULL AD02A43C-6F38-4F35-8C9E-E12422690BFB Bass, Matthew and Sarah 00000076 1 Yes Jackson, MS Central Gulf Coast MS Bass, Matthew and Sarah 00000076 Treatment Foster Home 506 Eagelwood Drive, Florence, MS 39073, (601)665-7169 Open/Re-opened 2011-04-01 00:00:00.000 Caucasian/White NULL Baptist You can see that both Averitte and Bass profile names have one record with NULL race, ethnicity, religion. How do I eliminate these rows (rows 2 and 4)? Here is my query currently: select distinct gp.group_profile_id, gp.profile_name, gp.license_number, gp.is_accepting, case when gp.is_accepting = 1 then 'Yes' when gp.is_accepting = 0 then 'No ' end as is_accepting_placement, mo.profile_name as managing_office, regions.[region_description] as region, pv.vendor_name, pv.id as vendor_id, at.description as applicant_type, dbo.GetGroupAddress(gp.group_profile_id, null, 0) as [Office Address], gsv.status_description, ri.[description] as race, ethnicity.description as ethnicity_desc, religion.description as religion from group_profile gp With (NoLock) --Office Information inner join group_profile_type gpt With (NoLock) on gp.group_profile_type_id = gpt.group_profile_type_id and gpt.type_code = 'FOSTERHOME' and gp.agency_id = @agency_id and gp.is_deleted = 0 inner join group_profile mo With (NoLock) on gp.managing_office_id = mo.group_profile_id left outer join payor_vendor pv With (NoLock) on gp.payor_vendor_id = pv.payor_vendor_id left outer join applicant_type at With (NoLock) on gp.applicant_type_id = at.applicant_type_id and at.is_foster_home = 1 inner join group_status_view gsv With (NoLock) on gp.group_profile_id = gsv.group_profile_id and gsv.status_value = 'OPEN' and gsv.effective_date = (Select max(b.effective_date) from group_status_view b With (NoLock) where gp.group_profile_id = b.group_profile_id) left outer join regions With (NoLock) on isnull(mo.regions_id, gp.regions_id) = regions.regions_id left join enrollment en on en.group_profile_id = gp.group_profile_id join event_log el on el.event_log_id = en.event_log_id left join people client on client.people_id = el.people_id left join race With (NoLock) on el.people_id = race.people_id left join group_profile_race gpr with (nolock) on gpr.race_info_id = race.race_info_id left join race_info ri with (nolock) on ri.race_info_id = gpr.race_info_id left join ethnicity With(NoLock) On client.ethnicity = ethnicity.ethnicity_id left join religion on client.religion = religion.religion_id

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• Cannot Logout of Facebook with Facebook C# SDK

  - by Ryan Smyth

  I think I've read just about everything out there on the topic of logging out of Facebook inside of a Desktop application. Nothing so far works. Specifically, I would like to log the user out so that they can switch identities, e.g. People sharing a computer at home could then use the software with their own Facebook accounts, but with no chance to switch accounts, it's quite messy. (Have not yet tested switching Windows users accounts as that is simply far too much to ask of the end user and should not be necessary.) Now, I should say that I have set the application to use these permissions: string[] permissions = new string[] { "user_photos", "publish_stream", "offline_access" }; So, "offline_access" is included there. I do not know if this does/should affect logging out or not. Again, my purpose for logging out is merely to switch users. (If there's a better approach, please let me know.) The purported solutions seem to be: Use the JavaScript SDK (FB.logout()) Use "m.facebook.com" instead Create your own URL (and possibly use m.facebook.com) Create your own URL and use the session variable (in ASP.NET) The first is kind of silly. Why resort to JavaScript when you're using C#? It's kind of a step backwards and has a lot of additional overhead in a desktop application. (I have not tried this as it's simply disgustingly messy to do this in a desktop application.) If anyone can confirm that this is the only working method, please do so. I'm desperately trying to avoid it. The second doesn't work. Perhaps it worked in the past, but my umpteen attempts to get it to work have all failed. The third doesn't work. I've tried umpteen dozen variations with zero success. The last option there doesn't work for a desktop application because it's not ASP.NET and you don't have a session variable to work with. The Facebook C# SDK logout also no longer works. i.e. public FacebookLoginDialog(string appId, string[] extendedPermissions, bool logout) { IDictionary<string, object> loginParameters = new Dictionary<string, object> { { "response_type", "token" }, { "display", "popup" } }; _navigateUri = FacebookOAuthClient.GetLoginUrl(appId, null, extendedPermissions, logout, loginParameters); InitializeComponent(); } I remember it working in the past, but it no longer works now. (Which truly puzzles me...) It instead now directs the user to the Facebook mobile page, where the user must manually logout. Now, I could do browser automation to automatically click the logout link for the user, however, this is prone to breaking if Facebook updates the mobile UI. It is also messy, and possibly a worse solution than trying to use the JavaScript SDK FB.logout() method (though not by much). I have searched for some kind of documentation, however, I cannot find anything in the Facebook developer documentation that illustrates how to logout an application. Has anyone solved this problem, or seen any documentation that can be ported to work with the Facebook C# SDK? I am certainly open to using a WebClient or HttpClient/Response if anyone can point to some documentation that could work with it. I simply have not been able to find any low-level documentation that shows how this approach could work. Thank you in advance for any advice, pointers, or links.

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• How do you stop scripters from slamming your website hundreds of times a second?

  - by davebug

  [update] I've accepted an answer, as lc deserves the bounty due to the well thought-out answer, but sadly, I believe we're stuck with our original worst case scenario: CAPTCHA everyone on purchase attempts of the crap. Short explanation: caching / web farms make it impossible for us to actually track hits, and any workaround (sending a non-cached web-beacon, writing to a unified table, etc.) slows the site down worse than the bots would. There is likely some pricey bit of hardware from Cisco or the like that can help at a high level, but it's hard to justify the cost if CAPTCHAing everyone is an alternative. I'll attempt to do a more full explanation in here later, as well as cleaning this up for future searchers (though others are welcome to try, as it's community wiki). I've added bounty to this question and attempted to explain why the current answers don't fit our needs. First, though, thanks to all of you who have thought about this, it's amazing to have this collective intelligence to help work through seemingly impossible problems. I'll be a little more clear than I was before: This is about the bag o' crap sales on woot.com. I'm the president of Woot Workshop, the subsidiary of Woot that does the design, writes the product descriptions, podcasts, blog posts, and moderates the forums. I work in the css/html world and am only barely familiar with the rest of the developer world. I work closely with the developers and have talked through all of the answers here (and many other ideas we've had). Usability of the site is a massive part of my job, and making the site exciting and fun is most of the rest of it. That's where the three goals below derive. CAPTCHA harms usability, and bots steal the fun and excitement out of our crap sales. To set up the scenario a little more, bots are slamming our front page tens of times a second screenscraping (and/or scanning our rss) for the Random Crap sale. The moment they see that, it triggers a second stage of the program that logs in, clicks I want One, fills out the form, and buys the crap. In current (2/6/2009) order of votes: lc: On stackoverflow and other sites that use this method, they're almost always dealing with authenticated (logged in) users, because the task being attempted requires that. On Woot, anonymous (non-logged) users can view our home page. In other words, the slamming bots can be non-authenticated (and essentially non-trackable except by IP address). So we're back to scanning for IPs, which a) is fairly useless in this age of cloud networking and spambot zombies and b) catches too many innocents given the number of businesses that come from one IP address (not to mention the issues with non-static IP ISPs and potential performance hits to trying to track this). Oh, and having people call us would be the worst possible scenario. Can we have them call you? BradC Ned Batchelder's methods look pretty cool, but they're pretty firmly designed to defeat bots built for a network of sites. Our problem is bots are built specifically to defeat our site. Some of these methods could likely work for a short time until the scripters evolved their bots to ignore the honeypot, screenscrape for nearby label names instead of form ids, and use a javascript-capable browser control. lc again "Unless, of course, the hype is part of you

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• MovieClip, counter almost working AS3

  - by VideoDnd

  How do I get my counter to work? This was over my director's head. Please include explanation, and feel free to comment. CONFUSION: I'm confused about the MovieClip container in as3. public class NumbersView extends MovieClip, so that seems to be a container. That may not be the problem, but that's where I got lost. CODE http://videodnd.weebly.com/ The working version of this code is fantastic. My code bellow is an attempt at revising it. The source has been adapted from various smart people. It's a work in progress LIBRARY OBJECT 'vertical number column' Name: mc-NumberImage Class: NumberImage OUTPUT ERRORS 'When I uncomment the code" 1023: Incompatible override. NumbersView... 1021: Duplicate function definition. NumbersView... //NUMBER DOCUMENT CLASS //IMPORT import flash.display.Sprite; import flash.events.Event; import flash.utils.Timer; import flash.events.TimerEvent; import flash.display.DisplayObject; import flash.display.MovieClip; import flash.utils.Dictionary; import caurina.transitions.Tweener; //COUNTER var timer:Timer = new Timer(1000); var count:int = 0; var fcount:int = 0; timer.addEventListener(TimerEvent.TIMER, incrementCounter); timer.start(); function incrementCounter(event:TimerEvent) { count++; fcount=int(count*count/1000); } function formatCount(i:int):String { var fraction:int = i % 100; var whole:int = i / 100; return ("000000000" + i).substr(-9, 9); } //------------------------------------------------------------------------ //PROBLEM AREA function enterFrameHandler(e:Event):void { // numbers.setTime(formatCount(fcount)); } var _listItems:Array = new Array(); var previousNums:Array; const numHeight:int = 120; var NumbersView:Sprite = new Sprite(); //var numbers:NumbersView = new NumbersView; //NUMBERSVIEW // function NumbersView($n:int):void { _listItems = new Array(); previousNums = new Array(); var item:NumberImage; var offset:int = _listItems.length; for (var i:Number = 0; i < 9; i++) { item = new NumberImage(); // }//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< //------------------------------------------------------------------------ //PUSH ARRAY addChild(item); item.x = i * item.width; _listItems.push(item); } //TWEENER 'Y SCROLLING' function setTime($number:String):void { var nums:Array = $number.split(""); for (var i:Number = 0; i < nums.length; i++) { if (nums[i] == previousNums[i]) continue; Tweener.removeTweens(_listItems[i]); var newY:int = int(nums[i]) * -numHeight; if (_listItems[i].y < 0) _listItems[i].y = numHeight; Tweener.addTween(_listItems[i], { y:newY, time:3 } ); } previousNums = nums; } D E S C R I P T I O N COUNTER: formatCount needs to get passed to Tweener STAGE: for loop, sets up children to be added to the stage NumbersView becomes item, item array adds children to stage TWEENER: advances the vertical number column every time the count fires adds and removes WHY - Learning - Benifit in simplifying the classes and putting it in one FLA

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• What do I need to write a small game on Linux?

  - by Michas

  I want to make a simple game: 2d, single-player, without tons of animations and special effects. I am not interested in ready to use game engines, I want to learn to write some code in a quite universal language. I am using Linux (AMD64) and looking for something easy with nice library for games. I do not want to mix few languages, most of them are in fact fast enough themselves for my needs. Cross platform would be an advantage, however all I need is a good Linux support. I have been considering few solutions. Ruby + Language looks very nice. + I am going to learn Ruby. - I am afraid I can have problems with additional libraries. - This thread about game libraries for Ruby could be longer. SDL + C + It is used for games. + It is very easy to set up. + There is a lot of additional libraries. + It is cross-platform. - The solution is quite low level. - The language is sometimes quite hard to read. QT + C++ + It is very easy to set up. + The standard QT libraries supports everything I can possibly need. + It is cross-platform. + The documentation is good. - The compilation is slow. - The language looks horrible. - The size of standard QT libraries is too big to comprehend. Environment of web browser + I am going to learn something more about this environment. + It is somewhat used for games. + It is quite cross-platform. - It would be too much experimental. Java + It is used for games. + The standard Java libraries supports everything I can possibly need. + It is cross-platform. - It is quite hard to set up. - The size of standard Java libraries is too big to comprehend. - The source code in Java could look better. - I think I do not want to learn Java. Google Go + I am going to learn Google Go. - There is big problem with libraries. - The solution would be quite low level. Python + It looks some people do games in Python, according to this thread. + It looks there are probably more libraries than for Ruby. - The Ruby language looks better. - I think I do not want to learn Python. C++ + something else + It is used for games. + It would be probably cross-platform. + There is a lot of libraries. - I do not need C++ extensions over C. - Compilation could be slow, there are fast compilers for C, not for C++. Haskell + I am going to learn Haskell. - Many things about programming computer games looks too much imperative. - It looks I can have some problems with libraries. - Compilation (GHC) looks slow. There is probably something more to consider. Does anyone have experience in making small games for Linux in non mainstream solutions? Does anyone have an advice for me?

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• Rails routing to XML/JSON without views gone mad

  - by John Schulze

  I have a mystifying problem. In a very simple Ruby app i have three classes: Drivers, Jobs and Vehicles. All three classes only consist of Id and Name. All three classes have the same #index and #show methods and only render in JSON or XML (this is in fact true for all their CRUD methods, they are identical in everything but name). There are no views. For example: def index @drivers= Driver.all respond_to do |format| format.js { render :json => @drivers} format.xml { render :xml => @drivers} end end def show @driver = Driver.find(params[:id]) respond_to do |format| format.js { render :json => @driver} format.xml { render :xml => @driver} end end The models are similarly minimalistic and only contain: class Driver< ActiveRecord::Base validates_presence_of :name end In routes.rb I have: map.resources :drivers map.resources :jobs map.resources :vehicles map.connect ':controller/:action/:id' map.connect ':controller/:action/:id.:format' I can perform POST/create, GET/index and PUT/update on all three classes and GET/read used to work as well until I installed the "has many polymorphs" ActiveRecord plugin and added to environment.rb: require File.join(File.dirname(__FILE__), 'boot') require 'has_many_polymorphs' require 'active_support' Now for two of the three classes I cannot do a read any more. If i go to localhost:3000/drivers they all list nicely in XML but if i go to localhost:3000/drivers/3 I get an error: Processing DriversController#show (for 127.0.0.1 at 2009-06-11 20:34:03) [GET] Parameters: {"id"=>"3"} [4;36;1mDriver Load (0.0ms)[0m [0;1mSELECT * FROM "drivers" WHERE ("drivers"."id" = 3) [0m ActionView::MissingTemplate (Missing template drivers/show.erb in view path app/views): app/controllers/drivers_controller.rb:14:in `show' ...etc This is followed a by another unexpected error: Processing ApplicationController#show (for 127.0.0.1 at 2009-06-11 21:35:52)[GET] Parameters: {"id"=>"3"} NameError (uninitialized constant ApplicationController::AreaAccessDenied): ...etc What is going on here? Why does the same code work for one class but not the other two? Why is it trying to do a #view on the ApplicationController? I found that if I create a simple HTML view for each of the three classes these work fine. To each class I add: format.html # show.html.erb With this in place, going to localhost:3000/drivers/3 renders out the item in HTML and I get no errors in the log. But if attach .xml to the URL it again fails for two of the classes (with the same error message as before) while one will output XML as expected. Even stranger, on the two failing classes, when adding .js to the URL (to trigger JSON rendering) I get the HTML output instead! Is it possible this has something to do with the "has many polymorphs" plugin? I have heard of people having routing issues after installing it. Removing "has many polymorphs" and "active support" from environment.rb (and rebooting the sever) seems to make no difference whatsoever. Yet my problems started after it was installed. I've spent a number of hours on this problem now and am starting to get a little desperate, Google turns up virtually no information which makes me suspect I must have missed something elementary. Any enlightenment or hint gratefully received! JS

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• Evidence-Based-Scheduling - are estimations only as accurate as the work-plan they're based on?

  - by Assaf Lavie

  I've been using FogBugz's Evidence Based Scheduling (for the uninitiated, Joel explains) for a while now and there's an inherent problem I can't seem to work around. The system is good at telling me the probability that a given project will be delivered at some date, given the detailed list of tasks that comprise the project. However, it does not take into account the fact that during development additional tasks always pop up. Now, there's the garbage-can approach of creating a generic task/scheduled-item for "last minute hacks" or "integration tasks", or what have you, but that clearly goes against the idea of aggregating the estimates of many small cases. It's often the case that during the development stage of a project you realize that there's a whole area your planning didn't cover, because, well, that's the nature of developing stuff that hasn't been developed before. So now your ~3 month project may very well turn into a 6 month project, but not because your estimations were off (you could be the best estimator in the world, for those task the comprised your initial work plan); rather because you ended up adding a whole bunch of new tasks that weren't there to begin with. EBS doesn't help you with that. It could, theoretically (I guess). It could, perhaps, measure the amount of work you add to a project over time and take that into consideration when estimating the time remaining on a given project. Just a thought. In other words, EBS works on a task basis, but not on a project/release basis - but the latter is what's important. It's what your boss typically cares about - delivery date, not the time it takes to finish each task along the way, and not the time it would have taken, if your planning was perfect. So the question is (yes, there's a question here, don't close it): What's your methodology when it comes to using EBS in FogBugz and how do you solve the problem above, which seems to be a main cause of schedule delays and mispredictions? Edit Some more thoughts after reading a few answers: If it comes down to having to choose which delivery date you're comfortable presenting to your higher-ups by squinting at the delivery-probability graph and choosing 80%, or 95%, or 60% (based on what, exactly?) then we've resorted to plain old buffering/factoring of our estimates. In which case, couldn't we have skipped the meticulous case by case hour-sized estimation effort step? By forcing ourselves to break down tasks that take more than a day into smaller chunks of work haven't we just deluded ourselves into thinking our planning is as tight and thorough as it could be? People may be consistently bad estimators that do not even learn from their past mistakes. In that respect, having an EBS system is certainly better than not having one. But what can we do about the fact that we're not that good in planning as well? I'm not sure it's a problem that can be solved by a similar system. Our estimates are wrong because of tendencies to be overly optimistic/pessimistic about certain tasks, and because of neglect to account for systematic delays (e.g. sick days, major bug crisis) - and usually not because we lack knowledge about the work that needs to be done. Our planning, on the other hand, is often incomplete because we simply don't have enough knowledge in this early stage; and I don't see how an EBS-like system could fill that gap. So we're back to methodology. We need to find a way to accommodate bad or incomplete work plans that's better than voodoo-multiplication.

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• NHibernate Proxy Creation

  - by Chris Meek

  I have a class structure like the following class Container { public virtual int Id { get; set; } public IList<Base> Bases { get; set; } } class Base { public virtual int Id { get; set; } public virtual string Name { get; set; } } class EnemyBase : Base { public virtual int EstimatedSize { get; set; } } class FriendlyBase : Base { public virtual int ActualSize { get; set; } } Now when I ask the session for a particular Container it normally gives me the concrete EnemyBase and FriendlyBase objects in the Bases collection. I can then (if I so choose) cast them to their concrete types and do something specific with them. However, sometime I get a proxy of the "Base" class which is not castable to the concrete types. The same method is used both times with the only exception being that in the case that I get proxies I have added some related entities to the session (think the friendly base having a collection of people or something like that). Is there any way I can prevent it from doing the proxy creating and why would it choose to do this in some scenarios? UPDATE The mappings are generated with the automap feature of fluentnhibernate but look something like this when exported <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-access="property" auto-import="true" default-cascade="none" default-lazy="true"> <class xmlns="urn:nhibernate-mapping-2.2" mutable="true" name="Base" table="`Base`"> <id name="Id" type="System.Int32, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"> <column name="Id" /> <generator class="MyIdGenerator" /> </id> <property name="Name" type="String"> <column name="Name" /> </property> <joined-subclass name="EnemyBase"> <key> <column name="Id" /> </key> <property name="EstimatedSize" type="Int"> <column name="EstimatedSize" /> </property> </joined-subclass> <joined-subclass name="FriendlyBase"> <key> <column name="Id" /> </key> <property name="ActualSize" type="Int"> <column name="ActualSize" /> </property> </joined-subclass> </class> </hibernate-mapping> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-access="property" auto-import="true" default-cascade="none" default-lazy="true"> <class xmlns="urn:nhibernate-mapping-2.2" mutable="true" name="Container" table="`Container`"> <id name="Id" type="System.Int32, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"> <column name="Id" /> <generator class="MyIdGenerator" /> </id> <bag cascade="all-delete-orphan" inverse="true" lazy="false" name="Bases" mutable="true"> <key> <column name="ContainerId" /> </key> <one-to-many class="Base" /> </bag> </class> </hibernate-mapping>

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• Forcing a transaction to rollback on validation errors in Seam

  - by Chris Williams

  Quick version: We're looking for a way to force a transaction to rollback when specific situations occur during the execution of a method on a backing bean but we'd like the rollback to happen without having to show the user a generic 500 error page. Instead, we'd like the user to see the form she just submitted and a FacesMessage that indicates what the problem was. Long version: We've got a few backing beans that use components to perform a few related operations in the database (using JPA/Hibernate). During the process, an error can occur after some of the database operations have happened. This could be for a few different reasons but for this question, let's assume there's been a validation error that is detected after some DB writes have happened that weren't detectible before the writes occurred. When this happens, we'd like to make sure all of the db changes up to this point will be rolled back. Seam can deal with this because if you throw a RuntimeException out of the current FacesRequest, Seam will rollback the current transaction. The problem with this is that the user is shown a generic error page. In our case, we'd actually like the user to be shown the page she was on with a descriptive message about what went wrong, and have the opportunity to correct the bad input that caused the problem. The solution we've come up with is to throw an Exception from the component that discovers the validation problem with the annotation: @ApplicationException( rollback = true ) Then our backing bean can catch this exception, assume the component that threw it has published the appropriate FacesMessage, and simply return null to take the user back to the input page with the error displayed. The ApplicationException annotation tells Seam to rollback the transaction and we're not showing the user a generic error page. This worked well for the first place we used it that happened to only be doing inserts. The second place we tried to use it, we have to delete something during the process. In this second case, everything works if there's no validation error. If a validation error does happen, the rollback Exception is thrown and the transaction is marked for rollback. Even if no database modifications have happened to be rolled back, when the user fixes the bad data and re-submits the page, we're getting: java.lang.IllegalArgumentException: Removing a detached instance The detached instance is lazily loaded from another object (there's a many to one relationship). That parent object is loaded when the backing bean is instantiated. Because the transaction was rolled back after the validation error, the object is now detached. Our next step was to change this page from conversation scope to page scope. When we did this, Seam can't even render the page after the validation error because our page has to hit the DB to render and the transaction has been marked for rollback. So my question is: how are other people dealing with handling errors cleanly and properly managing transactions at the same time? Better yet, I'd love to be able to use everything we have now if someone can spot something I'm doing wrong that would be relatively easy to fix. I've read the Seam Framework article on Unified error page and exception handling but this is geared more towards more generic errors your application might encounter.

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• Delphi 5: Ideas for simulating "Obsolete" or "Deprecated" methods?

  - by Ian Boyd

  i want to mark a method as obsolete, but Delphi 5 doesn't have such a feature. For the sake of an example, here is a made-up method with it's deprecated and new preferred form: procedure TStormPeaksQuest.BlowHodirsHorn; overload; //obsolete procedure TStormPeaksQuest.BlowHodirsHorn(UseProtection: Boolean); overload; Note: For this hypothetical example, we assume that using the parameterless version is just plain bad. There are problems with not "using protection" - which have no good solution. Nobody likes having to use protection, but nobody wants to not use protection. So we make the caller decide if they want to use protection or not when blowing Hodir's horn. If we default the parameterless version to continue not using protection: procedure TStormPeaksQuest.BlowHodirsHorn; begin BlowHodirsHorn(False); //No protection. Bad! end; then the developer is at risk of all kinds of nasty stuff. If we force the parameterless version to use protection: procedure TStormPeaksQuest.BlowHodirsHorn; begin BlowHodirsHorn(True); //Use protection; crash if there isn't any end; then there's a potential for problems if the developer didn't get any protection, or doesn't own any. Now i could rename the obsolete method: procedure TStormPeaksQuest.BlowHodirsHorn_Deprecatedd; overload; //obsolete procedure TStormPeaksQuest.BlowHodirsHorn(UseProtection: Boolean); overload; But that will cause a compile error, and people will bitch at me (and i really don't want to hear their whining). i want them to get a nag, rather than an actual error. i thought about adding an assertion: procedure TStormPeaksQuest.BlowHodirsHorn; //obsolete begin Assert(false, 'TStormPeaksQuest.BlowHodirsHorn is deprecated. Use BlowHodirsHorn(Boolean)'); ... end; But i cannot guarantee that the developer won't ship a version without assertions, causing a nasty crash for the customer. i thought about using only throwing an assertion if the developer is debugging: procedure TStormPeaksQuest.BlowHodirsHorn; //obsolete begin if DebugHook > 0 then Assert(false, 'TStormPeaksQuest.BlowHodirsHorn is deprecated. Use BlowHodirsHorn(Boolean)'); ... end; But i really don't want to be causing a crash at all. i thought of showing a MessageDlg if they're in the debugger (which is a technique i've done in the past): procedure TStormPeaksQuest.BlowHodirsHorn; //obsolete begin if DebugHook > 0 then MessageDlg('TStormPeaksQuest.BlowHodirsHorn is deprecated. Use BlowHodirsHorn(Boolean)', mtWarning, [mbOk], 0); ... end; but that is still too disruptive. And it has caused problems where the code is stuck at showing a modal dialog, but the dialog box wasn't obviously visible. i was hoping for some sort of warning message that will sit there nagging them - until they gouge their eyes out and finally change their code. i thought perhaps if i added an unused variable: procedure TStormPeaksQuest.BlowHodirsHorn; //obsolete var ThisMethodIsObsolete: Boolean; begin ... end; i was hoping this would cause a hint only if someone referenced the code. But Delphi shows a hint even if you don't call actually use the obsolete method. Can anyone think of anything else?

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