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• Converting LINQ to Twitter to Twitter API v1.1

  - by Joe Mayo

  Twitter recently updated their API to v1.1 (Current status: API v1.1). Naturally, LINQ to Twitter  needed to be updated too. This blog post outlines the changes made to LINQ to Twitter during this conversion and highlights important features that LINQ to Twitter developers will want to know. Overall Impact Generally speaking, Twitter API v1.1 is semantically very much the same as it’s predecessor. The base URL changed and so did a few resource segments, but the resources themselves are still intact. The good news is that LINQ to Twitter has always shielded the developer from this plumbing, so the entities, types, and filters didn’t change much at all.  The following sections describe what did  change. Authentication In Twitter API v1.0 authentication was not required for some resources, such as user timelines and search. However, that’s all changed because *all* queries must be authenticated in Twitter API v1.1. LINQ to Twitter has various types of authorizers you can use, supporting whatever OAuth options are available via Twitter.  You can see the LINQ to Twitter documentation, Securing Your Applications, for more info on OAuth support. The New Search One of the larger changes to the API was Search. To be more specific, the Search entity now contains a List<Status>, named Statuses, to hold results.  Additionally, any meta-data associated with the search is now in a property named SearchMetaData. The change to the Search entity and responses is the big change, but the good news is that your Search query syntax doesn’t change. Different Rate Limits The issue of rate limits itself is contentious, but this discussion is focused on the coding experience and I’ll leave the politics to those who prefer to engage in that activity. What’s important here is that both headers and resources have changed. You should review Twitter’s Rate Limit documentation to understand what the changes mean.  A quick explanation is that rate limits are applied individually to each resource in 15 minute time intervals. In LINQ to Twitter these changes surface on the Help entity, via HelpType.RateLimits. The RateLimits query has a Resources filter where you can specify a comma-separated list of categories to return rate limit info for.  The results materialize in the RateLimits dictionary, keyed on category. The Help entity also has a RateLimitsAuthorizationContext, holding the Access Token for the user performing queries – and to whom the rate limits apply. In addition to the new RateLimits query, there are new RateLimit headers that appear in the query response, whose HTTP header name is of the form X-Rate-Limit… which is different from the previous header name. LINQ to Twitter surfaces these headers via the existing properties of the TwitterContext instance. For anyone who retrieved rate limit information via the Headers property of TwitterContext, you should be aware of the new header names.  I haven’t done anything with Feature rate limit properties yet, but they appear to no longer be available – this will require more follow-up. Error Handling Twitter API v1.1 has a new format for Error Codes & Responses. LINQ to Twitter wraps these messages in the TwitterQueryException, which has been updated appropriately. The Message property of TwitterQueryException now reflects the Twitter error message, when available. There’s also a new ErrorCode that’s populated with the message error code. Parameters Most parameters stayed the same, but one of interest is Include Entities (different from LINQ to Twitter data object entities). Entities are metadata hanging off tweets, that provide start/end position in the tweet and other information for mentions, urls, hash tags, and media. Entities used to not be included unless you specified you wanted them. Now, in v1.1, entities are included by default for all APIs that return a Status.  If you were always setting IncludeEntities to true, then you won’t see a change. However, be aware that you’ll now be receiving additional data in your response from Twitter, which will explain a sudden increase in bandwidth utilization. This might or might not  matter to you  depending on the requirements of your application, but you should be aware of it. Everything Else There might be small changes here and there that I haven’t mentioned, but these were the ones you should be most aware of.  Streams didn’t change, but Twitter will be deprecating username/password authentication on public streams, in favor of OAuth, so you’ll be seeing me make that change some time in the future.  Also, Twitter will continue to evolve the API and you can expect that LINQ to Twitter will change accordingly. Summary The big changes to Twitter API were Authentication, Search, Rate Limits, and Error Handling. All API calls must be authenticated. You’ll need to change your code to read Search results differently, but the query is much the same as you use now. There’s a new RateLimits API, one of the Help queries.  Also, the new error messages are integrated into TwitterQueryException. Besides these changes, I expect  most others to be small or affect a smaller percentage of developers.  You can get the latest version of LINQ to Twitter from NuGet or visit the LINQ to Twitter download page at CodePlex.com.   @JoeMayo

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• Example: Controlling randomizer using code contracts

  - by DigiMortal

  One cool addition to Visual Studio 2010 is support for code contracts. Code contracts make sure that all conditions under what method is supposed to run correctly are met. Those who are familiar with unit tests will find code contracts easy to use. In this posting I will show you simple example about static contract checking (example solution is included). To try out code contracts you need at least Visual Studio 2010 Standard Edition. Also you need code contracts package. You can download package from DevLabs Code Contracts page. NB! Speakers, you can use the example solution in your presentations as long as you mention me and this blog in your sessions. Solution has readme.txt file that gives you steps to go through when presenting solution in sessions. This blog posting is companion posting for Visual Studio solution referred below. As an example let’s look at the following class. public class Randomizer {     public static int GetRandomFromRange(int min, int max)     {         var rnd = new Random();         return rnd.Next(min, max);     }       public static int GetRandomFromRangeContracted(int min, int max)     {         Contract.Requires(min < max, "Min must be less than max");           var rnd = new Random();         return rnd.Next(min, max);     } } GetRandomFromRange() method returns results without any checking. GetRandomFromRangeContracted() uses one code contract that makes sure that minimum value is less than maximum value. Now let’s run the following code. class Program {     static void Main(string[] args)     {         var random1 = Randomizer.GetRandomFromRange(0, 9);         Console.WriteLine("Random 1: " + random1);           var random2 = Randomizer.GetRandomFromRange(1, 1);         Console.WriteLine("Random 2: " + random2);           var random3 = Randomizer.GetRandomFromRangeContracted(5, 5);         Console.WriteLine("Random 3: " + random3);           Console.WriteLine(" ");         Console.WriteLine("Press any key to exit ...");         Console.ReadKey();     } } As we have not turned on support for code contracts the code runs without any problems and we get no warnings by Visual Studio that something is wrong. Now let’s turn on static checking for code contracts. As you can see then code still compiles without any errors but Visual Studio warns you about possible problems with contracts. Click on image to see it at original size.  When we open Error list and run our application we get the following output to errors list. Note that these messages are not shown immediately. There is little delay between application starting and appearance of these messages. So wait couple of seconds before going out of your mind. Click on image to see it at original size.  If you look at these warnings you can see that warnings show you illegal calls and also contracts against what they are going. Third warning points to GetRandomFromRange() method and shows that there should be also problem that can be detected by contract. Download Code Contracts example VS2010 solution | 30KB

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• Create speed baseline for local web file

  - by Michael Jasper

  Is there any tool or method that will load a localhost page a number of times, and return the averaged data for load times, onload events, Dom ready events, etc? I'd like to work on page speed optimization, but need a baseline before I begin. I have used both Google analytics and Webmaster tools, but I'd like an automated solutions that runs locally. My ideal solution would be a program or script that would take the path/file, number of iterations, and then take several minutes to load the page n times without cache and crunch numbers to create a baseline.

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• Timing Calculations for Opengl ES 2.0 draw calls

  - by Arun AC

  I am drawing a cube in OpenGL ES 2.0 in Linux. I am calculating the time taken for each frame using below function #define NANO 1000000000 #define NANO_TO_MICRO(x) ((x)/1000) uint64_t getTick() { struct timespec stCT; clock_gettime(CLOCK_MONOTONIC, &stCT); uint64_t iCurrTimeNano = (1000000000 * stCT.tv_sec + stCT.tv_nsec); // in Nano Secs uint64_t iCurrTimeMicro = NANO_TO_MICRO(iCurrTimeNano); // in Micro Secs return iCurrTimeMicro; } I am running my code for 100 frames with simple x-axis rotation. I am getting around 200 to 220 microsecs per frame. that means am i getting around (1/220microsec = 4545) FPS Is my GPU is that fast? I strongly doubt this result. what went wrong in the code? Regards, Arun AC

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• How do I resolve this exercise on C++? [closed]

  - by user40630

  (Card Shuffling and Dealing) Create a program to shuffle and deal a deck of cards. The program should consist of class Card, class DeckOfCards and a driver program. Class Card should provide: a) Data members face and suit of type int. b) A constructor that receives two ints representing the face and suit and uses them to initialize the data members. c) Two static arrays of strings representing the faces and suits. d) A toString function that returns the Card as a string in the form “face of suit.” You can use the + operator to concatenate strings. Class DeckOfCards should contain: a) A vector of Cards named deck to store the Cards. b) An integer currentCard representing the next card to deal. c) A default constructor that initializes the Cards in the deck. The constructor should use vector function push_back to add each Card to the end of the vector after the Card is created and initialized. This should be done for each of the 52 Cards in the deck. d) A shuffle function that shuffles the Cards in the deck. The shuffle algorithm should iterate through the vector of Cards. For each Card, randomly select another Card in the deck and swap the two Cards. e) A dealCard function that returns the next Card object from the deck. f) A moreCards function that returns a bool value indicating whether there are more Cards to deal. The driver program should create a DeckOfCards object, shuffle the cards, then deal the 52 cards. This above is the exercise I'm trying to solve. I'd be very much appreciated if someone could solve it and explain it to me. The main idea of the program is quite simple. What I don't get is how to build the constructor for the class DeckOfCards and how to generate the 52 cards of the deck with different suits and faces. Untill now I've managed to do this: #include <iostream> #include <vector> using namespace std; /* * */ /* a) Data members face and suit of type int. b) A constructor that receives two ints representing the face and suit and uses them to initialize the data members. c) Two static arrays of strings representing the faces and suits. d) A toString function that returns the Card as a string in the form “face of suit.” You can use the + operator to concatenate strings. */ class Card { public: Card(int, int); string toString(); private: int suit, face; static string faceNames[13]; static string suitNames[4]; }; string Card::faceNames[13] = {"Ace","Two","Three","Four","Five","Six","Seven","Eight","Nine","Ten","Queen","Jack","King"}; string Card::suitNames[4] = {"Diamonds","Clubs","Hearts","Spades"}; string Card::toString() { return faceNames[face]+" of "+suitNames[suit]; } Card::Card(int f, int s) :face(f), suit(s) { } /* Class DeckOfCards should contain: a) A vector of Cards named deck to store the Cards. b) An integer currentCard representing the next card to deal. c) A default constructor that initializes the Cards in the deck. The constructor should use vector function push_back to add each Card to the end of the vector after the Card is created and initialized. This should be done for each of the 52 Cards in the deck. d) A shuffle function that shuffles the Cards in the deck. The shuffle algorithm should iterate through the vector of Cards. For each Card, randomly select another Card in the deck and swap the two Cards. e) A dealCard function that returns the next Card object from the deck. f) A moreCards function that returns a bool value indicating whether there are more Cards to deal. */ class DeckOfCards { public: DeckOfCards(); void shuffleCards(); Card dealCard(); bool moreCards(); private: vector<Card> deck(52); int currentCard; }; int main(int argc, char** argv) { return 0; } DeckOfCards::DeckOfCards() { //I'm stuck here I have no idea of what to take out of here. //I still don't fully get the idea of class inside class and that's turning out as a problem. I try to find a way to set the suits and faces members of the class Card but I can't figure out how. for(int i=0; i<deck.size(); i++) { deck[i]//....There is no function to set them. They must be set when initialized. But how?? } } For easier reading: http://pastebin.com/pJeXMH0f

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• BizTalk 2009 - Service Instances: Last 100

  - by StuartBrierley

  Having previously talked about the lack of the traditional HAT in BizTalk 2009, the question then becomes how do you replicate some of the functionality that was previsouly relied on? I have already covered the Last 100 Messages Received, the Last 100 Messages Sent, and the Last 50 Suspended Messages queries so what about service instances? The BizTalk 2009 Group Hub allows you to search for suspended service instances and also running service instances, but not the two together. In BizTalk 2004 we had a query in HAT to return the last 100 service instances.  Lets create a direct replacement in the BizTalk 2009 Hatless environment. Basically we are creating a query to search for the last one hundred tracked service instances:

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• Installing Ubuntu 12.04.1 x64 with Fake RAID 1 [SOLVED]

  - by Arkadius

  I had: Software: Dual boot with Windows XP Ubuntu 10.04 LTS x32 Hardware Fake RAID 1 (mirroring) with 2x1 TB: Partition 1 - Windows Partition 2 - SWAP Partition 3 - / (root) Partition 4 - Extended Partition 5 - /home Partition 6 - /data arek@domek:/var/log/installer$ sudo fdisk -l Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000de1b9 Device Boot Start End Blocks Id System /dev/sda1 * 63 524297339 262148638+ 7 HPFS/NTFS/exFAT /dev/sda2 524297340 528506369 2104515 82 Linux swap / Solaris /dev/sda3 528506370 570468149 20980890 83 Linux /dev/sda4 570468150 1953118439 691325145 5 Extended /dev/sda5 570468213 675340469 52436128+ 83 Linux /dev/sda6 675340533 1953118439 638888953+ 83 Linux Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000de1b9 Device Boot Start End Blocks Id System /dev/sdb1 * 63 524297339 262148638+ 7 HPFS/NTFS/exFAT /dev/sdb2 524297340 528506369 2104515 82 Linux swap / Solaris /dev/sdb3 528506370 570468149 20980890 83 Linux /dev/sdb4 570468150 1953118439 691325145 5 Extended /dev/sdb5 570468213 675340469 52436128+ 83 Linux /dev/sdb6 675340533 1953118439 638888953+ 83 Linux arek@domek:/var/log/installer$ ls -l /dev/mapper/ total 0 crw------- 1 root root 10, 236 Oct 7 20:17 control lrwxrwxrwx 1 root root 7 Oct 7 20:17 pdc_jhjbcaha -> ../dm-0 lrwxrwxrwx 1 root root 7 Oct 7 20:17 pdc_jhjbcaha1 -> ../dm-1 lrwxrwxrwx 1 root root 7 Oct 7 20:17 pdc_jhjbcaha2 -> ../dm-2 lrwxrwxrwx 1 root root 7 Oct 7 20:17 pdc_jhjbcaha3 -> ../dm-3 lrwxrwxrwx 1 root root 7 Oct 7 20:17 pdc_jhjbcaha4 -> ../dm-4 lrwxrwxrwx 1 root root 7 Oct 7 20:17 pdc_jhjbcaha5 -> ../dm-5 lrwxrwxrwx 1 root root 7 Oct 7 20:17 pdc_jhjbcaha6 -> ../dm-6 I wanted to upgrade from 10.04 x32 to 12.04 x64 using FRESH installation. So, run installation of Ubuntu 12.04.1 x64 LTS using alternate CD. During the installation I selected manual partitioning and to: - Use and Format / (root) - Use and Format SWAP - Use and Keep data on /home - Use and Keep data on /data After I clicked "Continue" I get error creating and formatting SWAP partition. I go to terminal with Alt + F2 (?) and hit enter. I discovered that there was visible RAID as only disk with NO partitions. Something like this: arek@domek:/var/log/installer$ ls -l /dev/mapper/ lrwxrwxrwx 1 root root 7 Oct 7 20:17 /dev/mapper/pdc_jhjbcaha -> ../dm-0 arek@domek:/var/log/installer$ ls -l /dev/dm* brw-rw---- 1 root disk 252, 0 Oct 7 20:17 /dev/dm-0 So I switched to log console Alt+F3 (?) and saw errors like below: Oct 7 14:02:45 check-missing-firmware: /dev/.udev/firmware-missing does not exist, skipping Oct 7 14:02:45 check-missing-firmware: /run/udev/firmware-missing does not exist, skipping Oct 7 14:02:45 check-missing-firmware: no missing firmware in /dev/.udev/firmware-missing /run/udev/firmware-missing Oct 7 14:02:45 anna-install: Installing dmraid-udeb Oct 7 14:02:45 anna[12599]: DEBUG: retrieving dmraid-udeb 1.0.0.rc16-4.1ubuntu8 Oct 7 14:02:49 anna[12599]: DEBUG: retrieving libdmraid1.0.0.rc16-udeb 1.0.0.rc16-4.1ubuntu8 Oct 7 14:02:49 anna[12599]: DEBUG: retrieving kpartx-udeb 0.4.9-3ubuntu5 Oct 7 14:02:49 disk-detect: Serial ATA RAID disk(s) detected. Oct 7 14:02:55 disk-detect: Enabling dmraid support. Oct 7 14:02:55 disk-detect: RAID set "pdc_jhjbcaha" was activated Oct 7 14:02:55 HERE --> dmraid-activate: ERROR: Cannot retrieve RAID set information for pdc_jhjbcaha Oct 7 14:02:56 check-missing-firmware: /dev/.udev/firmware-missing does not exist, skipping Oct 7 14:02:56 check-missing-firmware: /run/udev/firmware-missing does not exist, skipping Oct 7 14:02:56 check-missing-firmware: no missing firmware in /dev/.udev/firmware-missing /run/udev/firmware-missing Oct 7 14:02:57 main-menu[428]: DEBUG: resolver (libnewt0.52): package doesn't exist (ignored) Oct 7 14:02:57 main-menu[428]: DEBUG: resolver (ext2-modules): package doesn't exist (ignored) Oct 7 14:02:57 main-menu[428]: INFO: Menu item 'partman-base' selected Oct 7 14:02:57 kernel: [ 316.512999] NTFS driver 2.1.30 [Flags: R/O MODULE]. Oct 7 14:02:57 kernel: [ 316.523221] Btrfs loaded Oct 7 14:02:57 kernel: [ 316.534781] JFS: nTxBlock = 8192, nTxLock = 65536 Oct 7 14:02:57 kernel: [ 316.554749] SGI XFS with ACLs, security attributes, realtime, large block/inode numbers, no debug enabled Oct 7 14:02:57 kernel: [ 316.555336] SGI XFS Quota Management subsystem Oct 7 14:02:58 md-devices: mdadm: No arrays found in config file or automatically Oct 7 14:02:58 partman: No matching physical volumes found Oct 7 14:02:58 partman: No volume groups found Oct 7 14:02:58 partman: Reading all physical volumes. This may take a while... Oct 7 14:02:58 partman-lvm: No volume groups found Oct 7 14:02:58 partman: Error running 'tune2fs -l /dev/mapper/pdc_jhjbcaha' Oct 7 14:02:58 partman: Error running 'tune2fs -l /dev/mapper/pdc_jhjbcaha' Oct 7 14:02:58 partman: Error running 'tune2fs -l /dev/mapper/pdc_jhjbcaha' Oct 7 14:06:11 HERE --> partman: mkswap: can't open '/dev/mapper/pdc_jhjbcaha2': No such file or directory Oct 7 14:07:28 init: starting pid 401, tty '/dev/tty2': '-/bin/sh' Oct 7 14:15:00 net/hw-detect.hotplug: Detected hotpluggable network interface eth0 Oct 7 14:15:00 net/hw-detect.hotplug: Detected hotpluggable network interface lo As You can see there are 2 errors Oct 7 14:02:55 dmraid-activate: ERROR: Cannot retrieve RAID set information for pdc_jhjbcaha and Oct 7 14:06:11 partman: mkswap: can't open '/dev/mapper/pdc_jhjbcaha2': No such file or directory I looked in the internet and try to run command "dmraid -ay" and get something like that: dmraid -ay /dev/mapper/pdc_jhjbcaha -> Already activated /dev/mapper/pdc_jhjbcaha1 -> Successfully activated /dev/mapper/pdc_jhjbcaha2 -> Successfully activated /dev/mapper/pdc_jhjbcaha3 -> Successfully activated /dev/mapper/pdc_jhjbcaha4 -> Successfully activated /dev/mapper/pdc_jhjbcaha5 -> Successfully activated /dev/mapper/pdc_jhjbcaha6 -> Successfully activated Then I returned to installer with Alt+F1 (?) and click "Return" to return to partitioning menu. I did NOT change anything just selected again "Continue" and everything goes smoothly. I hope this will help someone. arkadius

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• MVC & Windows Authentication

  - by TJ

  Changed the ValidateUser function  public bool ValidateUser(string userName, string password)         {             bool validation;             try             {                 LdapConnection ldc = new LdapConnection(new LdapDirectoryIdentifier((string)null, false, false));                 NetworkCredential nc = new NetworkCredential(userName, password, "domainname.com");                 ldc.Credential = nc;                 ldc.AuthType = AuthType.Negotiate;                 ldc.Bind(nc); // user has authenticated at this point, as the credentials were used to login to the dc.                  string myvar = ldc.SessionOptions.DomainName;                 validation = true;             }             catch (LdapException)             {                 validation = false;             }             return validation;         }

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• Why would one overload the && and & operator?

  - by acidzombie24

  The same question goes for | and ||. Why would one overload or 'use' the & and && operator? The only use i thought of are Bitwise Ands for int base types (but not float/decimals) using & logical short circuit for bools/functions that return bool. Using the && operator usually. I cant think of any classes that use those operators. Absolutely none. I know a class might support + (and not '-') which combine two strings together. I seen an object such as datetime overload '-' so two dates can be subtracted to make a timespan (obviously you cant add two dates) but i never seen &, &&, | and || used. Does anyone know of a use? In any language?

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• BigQuery - Best Practices for Running Queries on Massive Datasets

  BigQuery - Best Practices for Running Queries on Massive Datasets Join Michael Manoochehri and Ryan Boyd from the big data Developer Relations team on Friday, September 21th, at 10am PDT, as they discuss best practices for answering questions about massive datasets with Google BigQuery. They'll explore interesting Big Data use cases with some of our public datasets, using BigQuery's SQL-like language to return query results in seconds. They will also cover some of BigQuery's unique query functions as well. For a general overview of BigQuery, watch our overview video: youtu.be Please use the moderator below (goo.gl to ask your questions, which will be answered live! More info here: developers.google.com From: GoogleDevelopers Views: 0 0 ratings Time: 00:00 More in Science & Technology

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• WiFi and Bluetooth will not work on Dell Studio XPS 1645

  - by Ross

  Today I acquired a Dell XPS 1645. Ubuntu seems to run alright on it however The bluetooth is not detected and the WiFi doesn't work. The WiFi is especially weird because I actually have the restricted driver enabled for it. It also worked for a short while when I first booted into Ubuntu however now there isn't even an option to enable wireless. If anyone could possibly help me out with this I'd deeply appreciate it. I've not had to return to Windows for a good while and it's not something I want to have to do now.

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• Project Euler 6: (Iron)Python

  - by Ben Griswold

  In my attempt to learn (Iron)Python out in the open, here’s my solution for Project Euler Problem 6.  As always, any feedback is welcome. # Euler 6 # http://projecteuler.net/index.php?section=problems&id=6 # Find the difference between the sum of the squares of # the first one hundred natural numbers and the square # of the sum. import time start = time.time() square_of_sums = sum(range(1,101)) ** 2 sum_of_squares = reduce(lambda agg, i: agg+i**2, range(1,101)) print square_of_sums - sum_of_squares print "Elapsed Time:", (time.time() - start) * 1000, "millisecs" a=raw_input('Press return to continue')

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• sending credential to linkedIn website and get oauth_verifier without sign in again

  - by akash kumar

  i am facing problem regarding sending credentials to other website and after login(automatically not clicked on sign in here) and get oauth_verifier value Detail is bellow.... I want to send emailaddress and password through form(submit button)from my website(i.e liferay portal) to another website(suppose linkedIn) it should automatically authorize and return oauth_verifier to my website. that mean i dont want my website user to submit emailaddress and password to linkedIn again. actually i want to take emailaddress and password in my website and show the user LinkedIn connection,message,job posting in my website it self,i dont want to redirect user to LinkedIn website and sign in there and again come back to my website. I have taken consumer key and secret key from LinkedIn for my aplication. i am using linkedIn api and getting oauth_verifier for access token but for that i have to take user to LinkedIn for signIn, actually it should happen in backend

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• .NET Security Part 4

  - by Simon Cooper

  Finally, in this series, I am going to cover some of the security issues that can trip you up when using sandboxed appdomains. DISCLAIMER: I am not a security expert, and this is by no means an exhaustive list. If you actually are writing security-critical code, then get a proper security audit of your code by a professional. The examples below are just illustrations of the sort of things that can go wrong. 1. AppDomainSetup.ApplicationBase The most obvious one is the issue covered in the MSDN documentation on creating a sandbox, in step 3 – the sandboxed appdomain has the same ApplicationBase as the controlling appdomain. So let’s explore what happens when they are the same, and an exception is thrown. In the sandboxed assembly, Sandboxed.dll (IPlugin is an interface in a partially-trusted assembly, with a single MethodToDoThings on it): public class UntrustedPlugin : MarshalByRefObject, IPlugin { // implements IPlugin.MethodToDoThings() public void MethodToDoThings() { throw new EvilException(); } } [Serializable] internal class EvilException : Exception { public override string ToString() { // show we have read access to C:\Windows // read the first 5 directories Console.WriteLine("Pwned! Mwuahahah!"); foreach (var d in Directory.EnumerateDirectories(@"C:\Windows").Take(5)) { Console.WriteLine(d.FullName); } return base.ToString(); } } And in the controlling assembly: // what can possibly go wrong? AppDomainSetup appDomainSetup = new AppDomainSetup { ApplicationBase = AppDomain.CurrentDomain.SetupInformation.ApplicationBase } // only grant permissions to execute // and to read the application base, nothing else PermissionSet restrictedPerms = new PermissionSet(PermissionState.None); restrictedPerms.AddPermission( new SecurityPermission(SecurityPermissionFlag.Execution)); restrictedPerms.AddPermission( new FileIOPermission(FileIOPermissionAccess.Read, appDomainSetup.ApplicationBase); restrictedPerms.AddPermission( new FileIOPermission(FileIOPermissionAccess.pathDiscovery, appDomainSetup.ApplicationBase); // create the sandbox AppDomain sandbox = AppDomain.CreateDomain("Sandbox", null, appDomainSetup, restrictedPerms); // execute UntrustedPlugin in the sandbox // don't crash the application if the sandbox throws an exception IPlugin o = (IPlugin)sandbox.CreateInstanceFromAndUnwrap("Sandboxed.dll", "UntrustedPlugin"); try { o.MethodToDoThings() } catch (Exception e) { Console.WriteLine(e.ToString()); } And the result? Oops. We’ve allowed a class that should be sandboxed to execute code with fully-trusted permissions! How did this happen? Well, the key is the exact meaning of the ApplicationBase property: The application base directory is where the assembly manager begins probing for assemblies. When EvilException is thrown, it propagates from the sandboxed appdomain into the controlling assembly’s appdomain (as it’s marked as Serializable). When the exception is deserialized, the CLR finds and loads the sandboxed dll into the fully-trusted appdomain. Since the controlling appdomain’s ApplicationBase directory contains the sandboxed assembly, the CLR finds and loads the assembly into a full-trust appdomain, and the evil code is executed. So the problem isn’t exactly that the sandboxed appdomain’s ApplicationBase is the same as the controlling appdomain’s, it’s that the sandboxed dll was in such a place that the controlling appdomain could find it as part of the standard assembly resolution mechanism. The sandbox then forced the assembly to load in the controlling appdomain by throwing a serializable exception that propagated outside the sandbox. The easiest fix for this is to keep the sandbox ApplicationBase well away from the ApplicationBase of the controlling appdomain, and don’t allow the sandbox permissions to access the controlling appdomain’s ApplicationBase directory. If you do this, then the sandboxed assembly can’t be accidentally loaded into the fully-trusted appdomain, and the code can’t be executed. If the plugin does try to induce the controlling appdomain to load an assembly it shouldn’t, a SerializationException will be thrown when it tries to load the assembly to deserialize the exception, and no damage will be done. 2. Loading the sandboxed dll into the application appdomain As an extension of the previous point, you shouldn’t directly reference types or methods in the sandboxed dll from your application code. That loads the assembly into the fully-trusted appdomain, and from there code in the assembly could be executed. Instead, pull out methods you want the sandboxed dll to have into an interface or class in a partially-trusted assembly you control, and execute methods via that instead (similar to the example above with the IPlugin interface). If you need to have a look at the assembly before executing it in the sandbox, either examine the assembly using reflection from within the sandbox, or load the assembly into the Reflection-only context in the application’s appdomain. The code in assemblies in the reflection-only context can’t be executed, it can only be reflected upon, thus protecting your appdomain from malicious code. 3. Incorrectly asserting permissions You should only assert permissions when you are absolutely sure they’re safe. For example, this method allows a caller read-access to any file they call this method with, including your documents, any network shares, the C:\Windows directory, etc: [SecuritySafeCritical] public static string GetFileText(string filePath) { new FileIOPermission(FileIOPermissionAccess.Read, filePath).Assert(); return File.ReadAllText(filePath); } Be careful when asserting permissions, and ensure you’re not providing a loophole sandboxed dlls can use to gain access to things they shouldn’t be able to. Conclusion Hopefully, that’s given you an idea of some of the ways it’s possible to get past the .NET security system. As I said before, this post is not exhaustive, and you certainly shouldn’t base any security-critical applications on the contents of this blog post. What this series should help with is understanding the possibilities of the security system, and what all the security attributes and classes mean and what they are used for, if you were to use the security system in the future.

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• Immutable Method Java

  - by Chris Okyen

  In Java, there is the final keyword in lieu of the const keyword in c and c++. In the latter languages their is mutable and immutable methods such as stated in one answer by Johannes Schaub - litb the question how-many-and-which-are-the-uses-of-const-in-ce Use const to tell others methods won't change the logical state of this object. struct SmartPtr { int getCopies() const { return mCopiesMade; } }ptr1; ... int var = ptr.getCopies(); // returns mCopiesMade and is specified that to not modify objects state. How is this performed in Java?

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• Better than dynamic SQL - How to pass a list of comma separated IDs into a stored proc

  - by Rodney Vinyard

  Better than dynamic SQL - How to pass a list of comma separated IDs into a stored proc:     Derived form "Method 6" from a great article: ·         How to pass a list of values or array to SQL Server stored procedure ·          http://vyaskn.tripod.com/passing_arrays_to_stored_procedures.htm     Create PROCEDURE [dbo].[GetMyTable_ListByCommaSepReqIds] (@CommaSepReqIds varchar(500))   AS   BEGIN   select * from MyTable q               JOIN               dbo.SplitStringToNumberTable(@CommaSepReqIds) AS s               ON               q.MyTableId = s.ID End     ALTER FUNCTION [dbo].[SplitStringToNumberTable] (        @commaSeparatedList varchar(500) ) RETURNS @outTable table (        ID int ) AS BEGIN        DECLARE @parsedItem varchar(10), @Pos int          SET @commaSeparatedList = LTRIM(RTRIM(@commaSeparatedList))+ ','        SET @commaSeparatedList = REPLACE(@commaSeparatedList, ' ', '')        SET @Pos = CHARINDEX(',', @commaSeparatedList, 1)          IF REPLACE(@commaSeparatedList, ',', '') <> ''        BEGIN               WHILE @Pos > 0               BEGIN                      SET @parsedItem = LTRIM(RTRIM(LEFT(@commaSeparatedList, @Pos - 1)))                      IF @parsedItem <> ''                            BEGIN                                   INSERT INTO @outTable (ID)                                   VALUES (CAST(@parsedItem AS int)) --Use Appropriate conversion                            END                            SET @commaSeparatedList = RIGHT(@commaSeparatedList, LEN(@commaSeparatedList) - @Pos)                            SET @Pos = CHARINDEX(',', @commaSeparatedList, 1)               END        END           RETURN END

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• What are the IEEE and ACM good for?

  - by Joshua Fox

  Membership in the IEEE and ACM is sometimes portrayed as a sign of professionalism. But all that is involved, as far as I can tell, is sending them your money. In return, besides the potential resume line, these organizations sponsor conferences and journals. I can always attend a conference or subscribe to or submit a paper to a journal, whether I am a member or not. If being a member makes some of that cheaper, or is a prerequisite for admission then OK, but I still don't see the purpose of these organizations. The answer, as far as I can gather, is that their most important value is to provide some reading material. I'd suggest that this is not worth the money given the wide availability of other valuable reading materials.

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• Splitting Graph into distinct polygons in O(E) complexity

  - by Arthur Wulf White

  If you have seen my last question: trapped inside a Graph : Find paths along edges that do not cross any edges How do you split an entire graph into distinct shapes 'trapped' inside the graph(like the ones described in my last question) with good complexity? What I am doing now is iterating over all edges and then starting to traverse while always taking the rightmost turn. This does split the graph into distinct shapes. Then I eliminate all the excess shapes (that are repeats of previous shapes) and return the result. The complexity of this algorithm is O(E^2). I am wondering if I could do it in O(E) by removing edges I already traversed previously. My current implementation of that returns unexpected results.

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• Local Entities with NHibernate

  - by Ricardo Peres

  You may know that Entity Framework Code First has a nice property called Local which lets you iterate through all the entities loaded by the current context (first level cache). This comes handy at times, so I decided to check if it would be difficult to have it on NHibernate. It turned out it is not, so here it is! Another nice addition to an NHibernate toolbox! public static class SessionExtensions { public static IEnumerable<T> Local<T>(this ISession session) { ISessionImplementor impl = session.GetSessionImplementation(); IPersistenceContext pc = impl.PersistenceContext; foreach (Object key in pc.EntityEntries.Keys) { if (key is T) { yield return ((T) key); } } } } //simple usage IEnumerable<Post> localPosts = session.Local<Post>(); SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.brushes.CSharp.aliases = ['c#', 'c-sharp', 'csharp']; SyntaxHighlighter.all();

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• Naming a predicate: "precondition" or "precondition_is_met"?

  - by RexE

  In my web app framework, each page can have a precondition that needs to be satisfied before it can be displayed to the user. For example, if user 1 and user 2 are playing a back-and-forth role-playing game, user 2 needs to wait for user 1 to finish his turn before he can take his turn. Otherwise, the user is displayed a waiting page. This is implemented with a predicate: def precondition(self): return user_1.completed_turn The simplest name for this API is precondition, but this leads to code like if precondition(): ..., which is not really obvious. Seems to me like it is more accurate to call it precondition_is_met(), but not sure about that either. Is there a best practice for naming methods like this?

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• Which of these algorithms is best for my goal?

  - by JonathonG

  I have created a program that restricts the mouse to a certain region based on a black/white bitmap. The program is 100% functional as-is, but uses an inaccurate, albeit fast, algorithm for repositioning the mouse when it strays outside the area. Currently, when the mouse moves outside the area, basically what happens is this: A line is drawn between a pre-defined static point inside the region and the mouse's new position. The point where that line intersects the edge of the allowed area is found. The mouse is moved to that point. This works, but only works perfectly for a perfect circle with the pre-defined point set in the exact center. Unfortunately, this will never be the case. The application will be used with a variety of rectangles and irregular, amorphous shapes. On such shapes, the point where the line drawn intersects the edge will usually not be the closest point on the shape to the mouse. I need to create a new algorithm that finds the closest point to the mouse's new position on the edge of the allowed area. I have several ideas about this, but I am not sure of their validity, in that they may have far too much overhead. While I am not asking for code, it might help to know that I am using Objective C / Cocoa, developing for OS X, as I feel the language being used might affect the efficiency of potential methods. My ideas are: Using a bit of trigonometry to project lines would work, but that would require some kind of intense algorithm to test every point on every line until it found the edge of the region... That seems too resource intensive since there could be something like 200 lines that would have each have to have as many as 200 pixels checked for black/white.... Using something like an A* pathing algorithm to find the shortest path to a black pixel; however, A* seems resource intensive, even though I could probably restrict it to only checking roughly in one direction. It also seems like it will take more time and effort than I have available to spend on this small portion of the much larger project I am working on, correct me if I am wrong and it would not be a significant amount of code (100 lines or around there). Mapping the border of the region before the application begins running the event tap loop. I think I could accomplish this by using my current line-based algorithm to find an edge point and then initiating an algorithm that checks all 8 pixels around that pixel, finds the next border pixel in one direction, and continues to do this until it comes back to the starting pixel. I could then store that data in an array to be used for the entire duration of the program, and have the mouse re-positioning method check the array for the closest pixel on the border to the mouse target position. That last method would presumably execute it's initial border mapping fairly quickly. (It would only have to map between 2,000 and 8,000 pixels, which means 8,000 to 64,000 checked, and I could even permanently store the data to make launching faster.) However, I am uncertain as to how much overhead it would take to scan through that array for the shortest distance for every single mouse move event... I suppose there could be a shortcut to restrict the number of elements in the array that will be checked to a variable number starting with the intersecting point on the line (from my original algorithm), and raise/lower that number to experiment with the overhead/accuracy tradeoff. Please let me know if I am over thinking this and there is an easier way that will work just fine, or which of these methods would be able to execute something like 30 times per second to keep mouse movement smooth, or if you have a better/faster method. I've posted relevant parts of my code below for reference, and included an example of what the area might look like. (I check for color value against a loaded bitmap that is black/white.) // // This part of my code runs every single time the mouse moves. // CGPoint point = CGEventGetLocation(event); float tX = point.x; float tY = point.y; if( is_in_area(tX,tY, mouse_mask)){ // target is inside O.K. area, do nothing }else{ CGPoint target; //point inside restricted region: float iX = 600; // inside x float iY = 500; // inside y // delta to midpoint between iX,iY and tX,tY float dX; float dY; float accuracy = .5; //accuracy to loop until reached do { dX = (tX-iX)/2; dY = (tY-iY)/2; if(is_in_area((tX-dX),(tY-dY),mouse_mask)){ iX += dX; iY += dY; } else { tX -= dX; tY -= dY; } } while (abs(dX)>accuracy || abs(dY)>accuracy); target = CGPointMake(roundf(tX), roundf(tY)); CGDisplayMoveCursorToPoint(CGMainDisplayID(),target); } Here is "is_in_area(int x, int y)" : bool is_in_area(NSInteger x, NSInteger y, NSBitmapImageRep *mouse_mask){ NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; NSUInteger pixel[4]; [mouse_mask getPixel:pixel atX:x y:y]; if(pixel[0]!= 0){ [pool release]; return false; } [pool release]; return true; }

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• How to handle mutiple API calls using javascript/jquery

  - by James Privett

  I need to build a service that will call multiple API's at the same time and then output the results on the page (Think of how a price comparison site works for example). The idea being that as each API call completes the results are sent to the browser immediately and the page would get progressively bigger until all process are complete. Because these API calls may take several seconds each to return I would like to do this via javascript/jquery in order to create a better user experience. I have never done anything like this before using javascript/jquery so I was wondering if there was any frameworks/advice that anyone would be willing to share.

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• PostgreSQL data diff

  - by skanatek

  Note: this question is not about syncing database schema/structure Problem In my web application I have a PostgreSQL database server (PGS) and a (separate machine) business logic server (BLS) which regularly (every minute or two) queries 'SELECT ALL' against PGS. The problem is that the 'SELECT ALL' query can easily return 50-200 MB each time. It is obvious that it would be not so good architecture-wise to transfer so much data so frequently over the web. Possible solution What I would like to do is to run some diff tool on PGS and compare the new query with the previous query (all this should be done on PGS). Once the comparison is done I would like to get a dump from PGS and transfer it to BLS. I expect that a diff-based dump would be much, much smaller than the whole 'SELECT ALL' query. Question Is there any data diff tool for PostgreSQL that can do diffs that compare PostgreSQL data between 2 tables or 2 dumps? Note: I would prefer some open-source software tool.

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• Making profit from a social network

  - by James P.

  This follows similar questions but I'd like to see if anything particular comes out of it due to the nature of site. In short, I've taken up the role of webmaster for a small social network site and wish to make it profitable to at least cover the running costs. The site is linked to a commerce and presents are offered to members according to the number of points they've accumulated through various actions. The site is running on shared hosting so it's probably dirt cheap but the presents can be expensive as a whole and some money has already been invested into the project. One idea I have is to seek some sponsors that would be willing to offer presents or special offers in return for publicity. I don't know if this will be easy or not. I'm also looking into adapting hosting to perhaps move static files to a cheaper online storage medium (see Ideas for reducing storage needs and/or costs (lots of images)). Other suggestions are welcome.

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• After suspend, my monitor wont turn back on

  - by David

  I set my pc to suspend after 5 minutes of inactivity, when I return to my computer I mash a couple of keys and the pc turns back on and the drives start spinning etc etc, but I get no signal to either of my monitors. My peripherals are powered as the num/caps lock lights turn on and off. I should add I have two monitors, I have the same problem on both. As I am writing the last line from my previous paragraph keeps disappearing. I press control z and it comes back but kinda weird. Thanks in advance for any help :)

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