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  • A Guided Tour of Complexity

    - by JoshReuben
    I just re-read Complexity – A Guided Tour by Melanie Mitchell , protégé of Douglas Hofstadter ( author of “Gödel, Escher, Bach”) http://www.amazon.com/Complexity-Guided-Tour-Melanie-Mitchell/dp/0199798109/ref=sr_1_1?ie=UTF8&qid=1339744329&sr=8-1 here are some notes and links:   Evolved from Cybernetics, General Systems Theory, Synergetics some interesting transdisciplinary fields to investigate: Chaos Theory - http://en.wikipedia.org/wiki/Chaos_theory – small differences in initial conditions (such as those due to rounding errors in numerical computation) yield widely diverging outcomes for chaotic systems, rendering long-term prediction impossible. System Dynamics / Cybernetics - http://en.wikipedia.org/wiki/System_Dynamics – study of how feedback changes system behavior Network Theory - http://en.wikipedia.org/wiki/Network_theory – leverage Graph Theory to analyze symmetric  / asymmetric relations between discrete objects Algebraic Topology - http://en.wikipedia.org/wiki/Algebraic_topology – leverage abstract algebra to analyze topological spaces There are limits to deterministic systems & to computation. Chaos Theory definitely applies to training an ANN (artificial neural network) – different weights will emerge depending upon the random selection of the training set. In recursive Non-Linear systems http://en.wikipedia.org/wiki/Nonlinear_system – output is not directly inferable from input. E.g. a Logistic map: Xt+1 = R Xt(1-Xt) Different types of bifurcations, attractor states and oscillations may occur – e.g. a Lorenz Attractor http://en.wikipedia.org/wiki/Lorenz_system Feigenbaum Constants http://en.wikipedia.org/wiki/Feigenbaum_constants express ratios in a bifurcation diagram for a non-linear map – the convergent limit of R (the rate of period-doubling bifurcations) is 4.6692016 Maxwell’s Demon - http://en.wikipedia.org/wiki/Maxwell%27s_demon - the Second Law of Thermodynamics has only a statistical certainty – the universe (and thus information) tends towards entropy. While any computation can theoretically be done without expending energy, with finite memory, the act of erasing memory is permanent and increases entropy. Life & thought is a counter-example to the universe’s tendency towards entropy. Leo Szilard and later Claude Shannon came up with the Information Theory of Entropy - http://en.wikipedia.org/wiki/Entropy_(information_theory) whereby Shannon entropy quantifies the expected value of a message’s information in bits in order to determine channel capacity and leverage Coding Theory (compression analysis). Ludwig Boltzmann came up with Statistical Mechanics - http://en.wikipedia.org/wiki/Statistical_mechanics – whereby our Newtonian perception of continuous reality is a probabilistic and statistical aggregate of many discrete quantum microstates. This is relevant for Quantum Information Theory http://en.wikipedia.org/wiki/Quantum_information and the Physics of Information - http://en.wikipedia.org/wiki/Physical_information. Hilbert’s Problems http://en.wikipedia.org/wiki/Hilbert's_problems pondered whether mathematics is complete, consistent, and decidable (the Decision Problem – http://en.wikipedia.org/wiki/Entscheidungsproblem – is there always an algorithm that can determine whether a statement is true).  Godel’s Incompleteness Theorems http://en.wikipedia.org/wiki/G%C3%B6del's_incompleteness_theorems  proved that mathematics cannot be both complete and consistent (e.g. “This statement is not provable”). Turing through the use of Turing Machines (http://en.wikipedia.org/wiki/Turing_machine symbol processors that can prove mathematical statements) and Universal Turing Machines (http://en.wikipedia.org/wiki/Universal_Turing_machine Turing Machines that can emulate other any Turing Machine via accepting programs as well as data as input symbols) that computation is limited by demonstrating the Halting Problem http://en.wikipedia.org/wiki/Halting_problem (is is not possible to know when a program will complete – you cannot build an infinite loop detector). You may be used to thinking of 1 / 2 / 3 dimensional systems, but Fractal http://en.wikipedia.org/wiki/Fractal systems are defined by self-similarity & have non-integer Hausdorff Dimensions !!!  http://en.wikipedia.org/wiki/List_of_fractals_by_Hausdorff_dimension – the fractal dimension quantifies the number of copies of a self similar object at each level of detail – eg Koch Snowflake - http://en.wikipedia.org/wiki/Koch_snowflake Definitions of complexity: size, Shannon entropy, Algorithmic Information Content (http://en.wikipedia.org/wiki/Algorithmic_information_theory - size of shortest program that can generate a description of an object) Logical depth (amount of info processed), thermodynamic depth (resources required). Complexity is statistical and fractal. John Von Neumann’s other machine was the Self-Reproducing Automaton http://en.wikipedia.org/wiki/Self-replicating_machine  . Cellular Automata http://en.wikipedia.org/wiki/Cellular_automaton are alternative form of Universal Turing machine to traditional Von Neumann machines where grid cells are locally synchronized with their neighbors according to a rule. Conway’s Game of Life http://en.wikipedia.org/wiki/Conway's_Game_of_Life demonstrates various emergent constructs such as “Glider Guns” and “Spaceships”. Cellular Automatons are not practical because logical ops require a large number of cells – wasteful & inefficient. There are no compilers or general program languages available for Cellular Automatons (as far as I am aware). Random Boolean Networks http://en.wikipedia.org/wiki/Boolean_network are extensions of cellular automata where nodes are connected at random (not to spatial neighbors) and each node has its own rule –> they demonstrate the emergence of complex  & self organized behavior. Stephen Wolfram’s (creator of Mathematica, so give him the benefit of the doubt) New Kind of Science http://en.wikipedia.org/wiki/A_New_Kind_of_Science proposes the universe may be a discrete Finite State Automata http://en.wikipedia.org/wiki/Finite-state_machine whereby reality emerges from simple rules. I am 2/3 through this book. It is feasible that the universe is quantum discrete at the plank scale and that it computes itself – Digital Physics: http://en.wikipedia.org/wiki/Digital_physics – a simulated reality? Anyway, all behavior is supposedly derived from simple algorithmic rules & falls into 4 patterns: uniform , nested / cyclical, random (Rule 30 http://en.wikipedia.org/wiki/Rule_30) & mixed (Rule 110 - http://en.wikipedia.org/wiki/Rule_110 localized structures – it is this that is interesting). interaction between colliding propagating signal inputs is then information processing. Wolfram proposes the Principle of Computational Equivalence - http://mathworld.wolfram.com/PrincipleofComputationalEquivalence.html - all processes that are not obviously simple can be viewed as computations of equivalent sophistication. Meaning in information may emerge from analogy & conceptual slippages – see the CopyCat program: http://cognitrn.psych.indiana.edu/rgoldsto/courses/concepts/copycat.pdf Scale Free Networks http://en.wikipedia.org/wiki/Scale-free_network have a distribution governed by a Power Law (http://en.wikipedia.org/wiki/Power_law - much more common than Normal Distribution). They are characterized by hubs (resilience to random deletion of nodes), heterogeneity of degree values, self similarity, & small world structure. They grow via preferential attachment http://en.wikipedia.org/wiki/Preferential_attachment – tipping points triggered by positive feedback loops. 2 theories of cascading system failures in complex systems are Self-Organized Criticality http://en.wikipedia.org/wiki/Self-organized_criticality and Highly Optimized Tolerance http://en.wikipedia.org/wiki/Highly_optimized_tolerance. Computational Mechanics http://en.wikipedia.org/wiki/Computational_mechanics – use of computational methods to study phenomena governed by the principles of mechanics. This book is a great intuition pump, but does not cover the more mathematical subject of Computational Complexity Theory – http://en.wikipedia.org/wiki/Computational_complexity_theory I am currently reading this book on this subject: http://www.amazon.com/Computational-Complexity-Christos-H-Papadimitriou/dp/0201530821/ref=pd_sim_b_1   stay tuned for that review!

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  • Authenticating clients in the new WCF Http stack

    - by cibrax
    About this time last year, I wrote a couple of posts about how to use the “Interceptors” from the REST starker kit for implementing several authentication mechanisms like “SAML”, “Basic Authentication” or “OAuth” in the WCF Web programming model. The things have changed a lot since then, and Glenn finally put on our hands a new version of the Web programming model that deserves some attention and I believe will help us a lot to build more Http oriented services in the .NET stack. What you can get today from wcf.codeplex.com is a preview with some cool features like Http Processors (which I already discussed here), a new and improved version of the HttpClient library, Dependency injection and better TDD support among others. However, the framework still does not support an standard way of doing client authentication on the services (This is something planned for the upcoming releases I believe). For that reason, moving the existing authentication interceptors to this new programming model was one of the things I did in the last few days. In order to make authentication simple and easy to extend,  I first came up with a model based on what I called “Authentication Interceptors”. An authentication interceptor maps to an existing Http authentication mechanism and implements the following interface, public interface IAuthenticationInterceptor{ string Scheme { get; } bool DoAuthentication(HttpRequestMessage request, HttpResponseMessage response, out IPrincipal principal);} An authentication interceptors basically needs to returns the http authentication schema that implements in the property “Scheme”, and implements the authentication mechanism in the method “DoAuthentication”. As you can see, this last method “DoAuthentication” only relies on the HttpRequestMessage and HttpResponseMessage classes, making the testing of this interceptor very simple (There is no need to do some black magic with the WCF context or messages). After this, I implemented a couple of interceptors for supporting basic authentication and brokered authentication with SAML (using WIF) in my services. The following code illustrates how the basic authentication interceptors looks like. public class BasicAuthenticationInterceptor : IAuthenticationInterceptor{ Func<UsernameAndPassword, bool> userValidation; string realm;  public BasicAuthenticationInterceptor(Func<UsernameAndPassword, bool> userValidation, string realm) { if (userValidation == null) throw new ArgumentNullException("userValidation");  if (string.IsNullOrEmpty(realm)) throw new ArgumentNullException("realm");  this.userValidation = userValidation; this.realm = realm; }  public string Scheme { get { return "Basic"; } }  public bool DoAuthentication(HttpRequestMessage request, HttpResponseMessage response, out IPrincipal principal) { string[] credentials = ExtractCredentials(request); if (credentials.Length == 0 || !AuthenticateUser(credentials[0], credentials[1])) { response.StatusCode = HttpStatusCode.Unauthorized; response.Content = new StringContent("Access denied"); response.Headers.WwwAuthenticate.Add(new AuthenticationHeaderValue("Basic", "realm=" + this.realm));  principal = null;  return false; } else { principal = new GenericPrincipal(new GenericIdentity(credentials[0]), new string[] {});  return true; } }  private string[] ExtractCredentials(HttpRequestMessage request) { if (request.Headers.Authorization != null && request.Headers.Authorization.Scheme.StartsWith("Basic")) { string encodedUserPass = request.Headers.Authorization.Parameter.Trim();  Encoding encoding = Encoding.GetEncoding("iso-8859-1"); string userPass = encoding.GetString(Convert.FromBase64String(encodedUserPass)); int separator = userPass.IndexOf(':');  string[] credentials = new string[2]; credentials[0] = userPass.Substring(0, separator); credentials[1] = userPass.Substring(separator + 1);  return credentials; }  return new string[] { }; }  private bool AuthenticateUser(string username, string password) { var usernameAndPassword = new UsernameAndPassword { Username = username, Password = password };  if (this.userValidation(usernameAndPassword)) { return true; }  return false; }} This interceptor receives in the constructor a callback in the form of a Func delegate for authenticating the user and the “realm”, which is required as part of the implementation. The rest is a general implementation of the basic authentication mechanism using standard http request and response messages. I also implemented another interceptor for authenticating a SAML token with WIF. public class SamlAuthenticationInterceptor : IAuthenticationInterceptor{ SecurityTokenHandlerCollection handlers = null;  public SamlAuthenticationInterceptor(SecurityTokenHandlerCollection handlers) { if (handlers == null) throw new ArgumentNullException("handlers");  this.handlers = handlers; }  public string Scheme { get { return "saml"; } }  public bool DoAuthentication(HttpRequestMessage request, HttpResponseMessage response, out IPrincipal principal) { SecurityToken token = ExtractCredentials(request);  if (token != null) { ClaimsIdentityCollection claims = handlers.ValidateToken(token);  principal = new ClaimsPrincipal(claims);  return true; } else { response.StatusCode = HttpStatusCode.Unauthorized; response.Content = new StringContent("Access denied");  principal = null;  return false; } }  private SecurityToken ExtractCredentials(HttpRequestMessage request) { if (request.Headers.Authorization != null && request.Headers.Authorization.Scheme == "saml") { XmlTextReader xmlReader = new XmlTextReader(new StringReader(request.Headers.Authorization.Parameter));  var col = SecurityTokenHandlerCollection.CreateDefaultSecurityTokenHandlerCollection(); SecurityToken token = col.ReadToken(xmlReader);  return token; }  return null; }}This implementation receives a “SecurityTokenHandlerCollection” instance as part of the constructor. This class is part of WIF, and basically represents a collection of token managers to know how to handle specific xml authentication tokens (SAML is one of them). I also created a set of extension methods for injecting these interceptors as part of a service route when the service is initialized. var basicAuthentication = new BasicAuthenticationInterceptor((u) => true, "ContactManager");var samlAuthentication = new SamlAuthenticationInterceptor(serviceConfiguration.SecurityTokenHandlers); // use MEF for providing instancesvar catalog = new AssemblyCatalog(typeof(Global).Assembly);var container = new CompositionContainer(catalog);var configuration = new ContactManagerConfiguration(container); RouteTable.Routes.AddServiceRoute<ContactResource>("contact", configuration, basicAuthentication, samlAuthentication);RouteTable.Routes.AddServiceRoute<ContactsResource>("contacts", configuration, basicAuthentication, samlAuthentication); In the code above, I am injecting the basic authentication and saml authentication interceptors in the “contact” and “contacts” resource implementations that come as samples in the code preview. I will use another post to discuss more in detail how the brokered authentication with SAML model works with this new WCF Http bits. The code is available to download in this location.

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  • Adobe Air turn based multiplayer Game, sockets vs http bandwidth

    - by Arin Aivazian
    I am developing an Adobe Air multiplayer game for iPad. It is turn based and not realtime. It is like checkers game. I want to use a client server model. I have found 2 options to connect to server so far: socket connection and http requests My question is: Is the bandwidth requirement for socket connection vs http requests different? I need the game to work with very low speed internet connections

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  • Windows 7 IIS 7 unable to receive incoming HTTP traffic

    - by gregarobinson
     I was trying to load a test html page from a LAN server that is running Windows 7. I could load the page from the server, but not from machines within the LAN. It took a while to figure out, but it turned ot to be the firewall in Windows 7. Here is what I had to do: Windows Firewall with Advanced Security ---> Inbound Rules ---> Enable World Wide receive incoming HTTP trafficWeb Services (HTTP Traffic-In)

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  • The Kayak Framework: An easy way to speak HTTP with .NET

    Kayak is a lightweight HTTP server for the CLR, and the Kayak Framework is a utility for mapping HTTP requests to C# method invocations. With Kayak, you can skip the bulk, hassle, and overhead of IIS and ASP.NET. Kayak enables you to do more with less syntax, and is easy to configure to work in any way you care to dream up.

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  • Restricting URL w.r.t HTTP method and setting different authentication mechanism for each

    - by user31745
    I shall start with an example. I want to restrict to POST requests only for http://path/to/logical/abc.xml and restrict to GET only for http://path/to/logical/def.xml. How do I put constraints like this as the paths are logical and location directive is not supported in .htaccess? The actual problem is to set different authentication type(basic, digest) on diff logical file.for eg. for abc.xml I want to authenticate for Basic type of authentication and def.xml with digest.

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  • Scraping a page from a secure URL which is possibly using a session ID

    - by VN44CA
    How to scrape a page like this. https://www.procom.ca/JobList.aspx?keywords=&Cities=&reference=&JobType=0 It is secure, and requires a referrer? I can't get anything using wget or httplib2. If you go through this page, you get a list and it works on a browser but not the command line. https://www.procom.ca/jobsearch.aspx I am interested in command line fetching. thx

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  • XNA Notes 011

    - by George Clingerman
    Even with a lot of the XNA community working on Dream Build Play entries ( I swear I’m going to finish mine this year!) people are still finding time to do side projects and be amazingly active in the XNA and XBLIG community. With my one eye on my code and one eye on the community, here’s what I noticed these over achievers doing this past week! Time Critical XNA News: Xbox LIVE Indie Games sales data will be delayed March 17-20th due to some schedule maintenance http://create.msdn.com/en-us/news/indie_games_data_delay_march2011 GameMarx is releasing a series of videos to help raise donations for victims of the earthquakes and tsunami in Japan. Help out if you can! http://www.gamemarx.com/video/special/29/help-japan-sushido.aspx XNA MVPs: Catalin Zima shares his thoughts on the MVP summit and my book! http://www.catalinzima.com/2011/03/mvp-summit-2011/ Glenn Wilson (@mykre) helps the XNA team announce some new educational content that you don’t want to miss if you’re porting your app or game to Windows Phone 7 http://www.virtualrealm.com.au/Blog/tabid/62/EntryId/653/Porting-your-App-or-Game-to-Windows-Phone-7.aspx and Windows Phone 7 from scratch http://www.virtualrealm.com.au/Blog/tabid/62/EntryId/654/Windows-Phone-from-Scratch.aspx and shares a link to some free architectural models and textures http://twitter.com/#!/Mykre/status/46410160784158720 George (that’s me!) shares his MVP Summit 2011 summary and XBLIG thoughts http://geekswithblogs.net/clingermangw/archive/2011/03/15/144366.aspx XNA Developers: @SmallCaveGames shares a Code of Ethics for Xbox LIVE Indie Game Developers http://smallcavegames.blogspot.com/2011/03/unofficial-xblig-developers-code-of.html Derek S adds more Xbox LIVE Indie Game studios to his master list of XBLIG links http://twitter.com/#!/Mr_Deeke/status/46140996056125440 http://xbl-indieverse.blogspot.com/p/xblig-links.html Making games and want to help kids? Then share your story with GameFace: America! http://gameitupinitiative.com/about-the-initiative/programs/gameface-america/ Xbox LIVE Indie Games (XBLIG): XonaGames shares some video footage of their booth from GDC 2011 Video 1: http://youtu.be/lxIV9nk3Gq4 Video 2: http://youtu.be/GgfrjqkxR_o Video 3: http://youtu.be/yVcpXrTX7SQ Joystiq on Mommy’s Best Games Serious Sam Double D http://www.joystiq.com/2011/03/16/the-most-important-thing-about-serious-sam-double-d/ And The Escapist recommends that gamers start learning to avoid cleavage now http://www.escapistmagazine.com/news/view/108543-Boobie-Bomber-Makes-First-Appearance-in-Serious-Sam-Double-D Magiko Gaming started a blog on the XBLIG dashboard daily Top 10 games in the US. Good way to go back in time and look at the history of which games were in the the Top 10. http://dailytop10indiegames.wordpress.com/ Where are they going now? XBLIG developers at a crossroads.. http://www.gamesetwatch.com/2011/03/where_are_they_going_now_xblig.php http://www.gamasutra.com/view/news/33527/InDepth_Where_Are_They_Going_Now_XBLIG_Developers_At_A_Crossroads_.php BinaryTweed’s Clover: A Curious Tail is Xbox LIVE’s Deal of the Week! http://www.armlessoctopus.com/2011/03/15/what-luck-clover-a-curious-tale-is-half-price-this-week/ Looking for an Xbox LIVE Indie Game to buy? Writings of Mass Deduction has over 125 suggestions at this point! http://writingsofmassdeduction.com/ SkaStudios shares Vampire Smile Achievements AND their PAX East 2011 Both Setup video http://www.ska-studios.com/2011/03/14/vampire-smile-achievement/ http://www.ska-studios.com/2011/03/15/pax-booth-setup-time-lapse/ MasterBlud and VVGTV starts a new community for XBLIG developers and gamers to join http://vvgtv.forumotion.com/ Raymond Matthews (@DrakstarMatryx) covers Mommy’s Best Games getting Serious http://www.darkstarmatryx.com/?p=286 XNA Development: Dave Henry (@mort8088) posts the 4th tutorial in his series XNA 4.0 SpriteBatch extended http://mort8088.com/2011/03/11/xna-4-0-tutorial-4-spritebatch-extended/ Tutorial 5 - Creating a manual blank texture http://mort8088.com/2011/03/13/xna-4-tutorial-5-manual-blank-texture/ XNA 4.0 Tutorial 6 - Spritesheet Object http://mort8088.com/2011/03/18/xna-4-0-tutorial-6-spritesheet-object/ Jason Mitchell shares a tutorial on setting the alpha value for spritebatch in XNA 4.0 http://www.jason-mitchell.com/index.php/2011/03/13/setting-alpha-value-for-spritebatch-draw-in-xna-4/ XNA for Silverlight Developers: Part 7 - Collision Detection http://www.silverlightshow.net/items/XNA-for-Silverlight-developers-Part-7-Collision-detection.aspx Markus Ewald (@Cygon4) shares the full Ninject 2.0 binding for XNA and Sunburn http://twitter.com/#!/Cygon4/status/48330203826622464 Michael B. McLaughlin shares an AccelerometerInput XNA GameComponent he created (which I’m probably going to snag for a game I’m working on...) http://geekswithblogs.net/mikebmcl/archive/2011/03/17/accelerometerinput-xna-gamecomponent.aspx Extra Credit tackles the building of a good tutorial. Must watch for all Indie game devs (thanks for pointing it out Evan Johnson!) http://twitter.com/#!/johnsonevan/status/48452115680604160 http://www.escapistmagazine.com/videos/view/extra-credits/2921-Tutorials-101 ExEn is fully funded at this point so definitely something for XBLIG developers to keep an eye on as they consider releasing their games on other platforms http://rockethub.com/projects/752-exen-xna-for-iphone-android-and-silverlight Channel 9 and Greg Duncan post Mixing the Game State Management and Platformer XNA Recipes http://channel9.msdn.com/coding4fun/blog/Mixing-the-Game-State-Management-and-Platformer-XNA-Recipes Sgt. Conker has noticed Mike McLaughlin has been crazy productive and has done a recap of his recent posts http://www.sgtconker.com/2011/03/recap-of-mikebmcls-posts/

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  • Token based Authentication for WCF HTTP/REST Services: Authentication

    - by Your DisplayName here!
    This post shows some of the implementation techniques for adding token and claims based security to HTTP/REST services written with WCF. For the theoretical background, see my previous post. Disclaimer The framework I am using/building here is not the only possible approach to tackle the problem. Based on customer feedback and requirements the code has gone through several iterations to a point where we think it is ready to handle most of the situations. Goals and requirements The framework should be able to handle typical scenarios like username/password based authentication, as well as token based authentication The framework should allow adding new supported token types Should work with WCF web programming model either self-host or IIS hosted Service code can rely on an IClaimsPrincipal on Thread.CurrentPrincipal that describes the client using claims-based identity Implementation overview In WCF the main extensibility point for this kind of security work is the ServiceAuthorizationManager. It gets invoked early enough in the pipeline, has access to the HTTP protocol details of the incoming request and can set Thread.CurrentPrincipal. The job of the SAM is simple: Check the Authorization header of the incoming HTTP request Check if a “registered” token (more on that later) is present If yes, validate the token using a security token handler, create the claims principal (including claims transformation) and set Thread.CurrentPrincipal If no, set an anonymous principal on Thread.CurrentPrincipal. By default, anonymous principals are denied access – so the request ends here with a 401 (more on that later). To wire up the custom authorization manager you need a custom service host – which in turn needs a custom service host factory. The full object model looks like this: Token handling A nice piece of existing WIF infrastructure are security token handlers. Their job is to serialize a received security token into a CLR representation, validate the token and turn the token into claims. The way this works with WS-Security based services is that WIF passes the name/namespace of the incoming token to WIF’s security token handler collection. This in turn finds out which token handler can deal with the token and returns the right instances. For HTTP based services we can do something very similar. The scheme on the Authorization header gives the service a hint how to deal with an incoming token. So the only missing link is a way to associate a token handler (or multiple token handlers) with a scheme and we are (almost) done. WIF already includes token handler for a variety of tokens like username/password or SAML 1.1/2.0. The accompanying sample has a implementation for a Simple Web Token (SWT) token handler, and as soon as JSON Web Token are ready, simply adding a corresponding token handler will add support for this token type, too. All supported schemes/token types are organized in a WebSecurityTokenHandlerCollectionManager and passed into the host factory/host/authorization manager. Adding support for basic authentication against a membership provider would e.g. look like this (in global.asax): var manager = new WebSecurityTokenHandlerCollectionManager(); manager.AddBasicAuthenticationHandler((username, password) => Membership.ValidateUser(username, password));   Adding support for Simple Web Tokens with a scheme of Bearer (the current OAuth2 scheme) requires passing in a issuer, audience and signature verification key: manager.AddSimpleWebTokenHandler(     "Bearer",     "http://identityserver.thinktecture.com/trust/initial",     "https://roadie/webservicesecurity/rest/",     "WFD7i8XRHsrUPEdwSisdHoHy08W3lM16Bk6SCT8ht6A="); In some situations, SAML token may be used as well. The following configures SAML support for a token coming from ADFS2: var registry = new ConfigurationBasedIssuerNameRegistry(); registry.AddTrustedIssuer( "d1 c5 b1 25 97 d0 36 94 65 1c e2 64 fe 48 06 01 35 f7 bd db", "ADFS"); var adfsConfig = new SecurityTokenHandlerConfiguration(); adfsConfig.AudienceRestriction.AllowedAudienceUris.Add( new Uri("https://roadie/webservicesecurity/rest/")); adfsConfig.IssuerNameRegistry = registry; adfsConfig.CertificateValidator = X509CertificateValidator.None; // token decryption (read from config) adfsConfig.ServiceTokenResolver = IdentityModelConfiguration.ServiceConfiguration.CreateAggregateTokenResolver();             manager.AddSaml11SecurityTokenHandler("SAML", adfsConfig);   Transformation The custom authorization manager will also try to invoke a configured claims authentication manager. This means that the standard WIF claims transformation logic can be used here as well. And even better, can be also shared with e.g. a “surrounding” web application. Error handling A WCF error handler takes care of turning “access denied” faults into 401 status codes and a message inspector adds the registered authentication schemes to the outgoing WWW-Authenticate header when a 401 occurs. The next post will conclude with authorization as well as the source code download.   (Wanna learn more about federation, WIF, claims, tokens etc.? Click here.)

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  • How does a web server/the http protocol handle version control and compression?

    - by Sune Rasmussen
    When a client browser requests a file from the web server, I know that some kind of check is performed, because the files needed to serve the web page may already be cached by the web browser. So, if a file exists in the cache, no files are sent. But if the file on the server has changed since the file was cached in the browser, the file is sent and updated anyhow. Then, if you have compression like gzipping enabled on the server, the files that are to be provided to the client must be gzipped on the way, requiring some amount of server side processing. But how is this managed? The logical approach seems to me, that the web server should have a cache as well, containing the newest version of all files that have been requested within a certain time span, thus a compressed version of these files, so that compression would not have to be done each time a files is requested. And also, how are files eventually requested? Does the browser ask for files, each time it encounters one in the HTML code and the specific file is not stored in the local cache, or does it sum all the files that are needed up and ask for the whole bunch at the same time? But that's only guessing from a programming point of view, and I don't really know. If the answers are very different among web server systems, I'm primarily interested in Apache, but other answers are appreciated, too.

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  • mod_rewrite to page with HTTP auth

    - by Joe
    I'm trying to use modrewrite to proxy http:://myserver/cam1 to an internal, http-auth protected server at http:://admin:[email protected]/cgi/mjpg/mjpg.cgi No matter what I try, though, requests to http:://myserver/cam1 always prompt me for the username and password. I've tried all of these to no avail. RewriteRule ^/cam1 http://admin:[email protected]/cgi/mjpg/mjpg.cgi [P,L] RewriteRule ^/cam1 http://192.168.99.130/cgi/mjpg/mjpg.cgi [E=Authorization:Basic\ YWRtaW46YWRtaW4=,P,L] RewriteRule ^/cam1 http://192.168.99.130/cgi/mjpg/mjpg.cgi [E=HTTP_USERID:admin,E=HTTP_PASSWORD:admin,P,L]` Anybody have any other ideas?

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  • Redirect HTTP requests based on subdomain address without changing accessed URL?

    - by tputkonen
    Let's say I have a domain: www.mydomain.com And I ordered a new domain: abc.newdomain.com Both domains are hosted in the same ISP, so currently requests to either of those addresses result in the same page being shown. I want to redirect all requests to abc.newdomain.com to folder /wp so that when users access abc.newdomain.com they would see whatever is inside folder /wp without seeing the URL change. Questions: 1) How can I achieve this using .htaccess? 2) How can I prevent users from accessing directly /wp directory (meaning that www.mydomain.com/wp would be blocked)?

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  • Redirect HTTP requests based on subdomain address without changing accessed URL?

    - by tputkonen
    Let's say I have a domain, www.mydomain.com. And I ordered a new domain, abc.newdomain.com. Both domains are hosted in the same ISP, so currently requests to either of those addresses result in the same page being shown. I want to redirect all requests to abc.newdomain.com to folder /wp so that when users access abc.newdomain.com they would see whatever is inside folder /wp without seeing the URL change. Questions: How can I achieve this using .htaccess? How can I prevent users from accessing directly /wp directory (meaning that www.mydomain.com/wp would be blocked)?

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  • How can I setup my local Nginx server so I can edit the files?

    - by Shane Grant
    I have my local development machine running Arch Linux, Nginx, PHP-FPM and MySQL. In order for the websites I am working on to run the files need to be owned by the http user. The files are currently located in folders like this: /srv/http/site1/ /srv/http/site2/ When I use the following chown command on the http folder the sites work fine, but I cannot edit the files with my user: chown -R http.users /srv/http When I do this the sites do not work, but I can edit the files: chown -R shane.http /srv/http How can I make it so that my user can edit the files, and the web server can run them at the same time? Thank you

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  • Why does mod_security require an ACCEPT HTTP header field?

    - by ripper234
    After some debugging, I found that the core ruleset of mod_security blocks requests that don't have the (optional!) ACCEPT header field. This is what I find in the logs: ModSecurity: Warning. Match of "rx ^OPTIONS$" against "REQUEST_METHOD" required. [file "/etc/apache2/conf.d/modsecurity/modsecurity_crs_21_protocol_anomalies.conf"] [line "41"] [id "960015"] [msg "Request Missing an Accept Header"] [severity "CRITICAL"] [tag "PROTOCOL_VIOLATION/MISSING_HEADER"] [hostname "example.com"] [uri "/"] [unique_id "T4F5@H8AAQEAAFU6aPEAAAAL"] ModSecurity: Access denied with code 400 (phase 2). Match of "rx ^OPTIONS$" against "REQUEST_METHOD" required. [file "/etc/apache2/conf.d/modsecurity/optional_rules/modsecurity_crs_21_protocol_anomalies.conf"] [line "41"] [id "960015"] [msg "Request Missing an Accept Header"] [severity "CRITICAL"] [tag "PROTOCOL_VIOLATION/MISSING_HEADER"] [hostname "example.com"] [uri "/"] [unique_id "T4F5@H8AAQEAAFU6aPEAAAAL"] Why is this header required? I understand that "most" clients send these, but why is their absence considered a security threat?

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  • Serve web application error messages from Http server [closed]

    - by licorna
    I have nginx as a http server with tomcat as a backend (using proxy_pass). It works great but I want to define my own error pages (404, 500, etc.) and that they are served by nginx and not tomcat. For example I have the following resource: https://domain.com/resource which doesn't exist. If I [GET] that URL then I get a Not Found message from Tomcat and not from nginx. What I want is that every time Tomcat responds with a 404 (or any other error message) nginx sends itself a message to the user: some html file accessible by nginx. The way I have my nginx server configured is very easy, just: location / { proxy_pass http://localhost:8080/<webapp-name>/; } And I've configured port 8080, which is tomcat, as not accessible from outside this machine. I don't think that using different location directives in nginx configuration will work, because there are some resources that depend on the URL: https://domain.com/customer/<non-existent-customer-name>/[GET] Will always return 404 (or any other error message), while: https://domain.com/customer/<existent-customer>/[GET] Will return anything different from 404 (the customer exists). Is there any way of serving Tomcat (Application Server) error messages with Nginx (http Server)? To check the message sent by the proxy_pass directive and act upon it?

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  • HTTP Protocal

    I have worked with the HTTP protocal for about ten years now and I have found it to be incredibly usefull for transfering data espicaly for remote systems and regardless of the network enviroment. Prior to the existance of web services, developers use to use HTTP to screen scrap data off of web pages in order to interact with remote systems, and then process the data as they needed. I use to use the HTTPWebRequest and HTTPWebRespones classes in order to screen scrap data from various sites that had information I needed to use if no web service was avalible. This allowed me to call just about any webpage and grab all of the content on the page. Below is piece of a web spider that I build about 5-7 years ago. The spider uses the HTTP protocal to requst webpages and then parse the data that is returned.  At the time of writing the spider I wanted to create a searchable index of sites I frequented. // C# 2.0 Framework// Creating a request for a specfic webpageHttpWebRequest webreq = (HttpWebRequest)WebRequest.Create(_Url); // Storeing the response of the webrequestwebresp = (HttpWebResponse)webreq.GetResponse(); StreamReader loResponseStream = new StreamReader(webresp.GetResponseStream()); _Content = loResponseStream.ReadToEnd(); // Adjust the Encoding of Responsestring charset = "";EncodeString(ref _Content, ref charset);loResponseStream.Close(); //Parse Data from the Respone_Content = _Content.Replace("\n", "");_Head = GetTagByName("Head", _Content);_Title = GetTagByName("title", _Content);_Body = GetTagByName("body", _Content);

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  • How should an API use http basic authentication

    - by user1626384
    When an API requires that a client authenticates to it, i've seen two different scenarios used and I am wondering which case I should use for my situation. Example 1. An API is offered by a company to allow third parties to authenticate with a token and secret using HTTP Basic. Example 2. An API accepts a username and password via HTTP Basic to authenticate an end user. Generally they get a token back for future requests. My Setup: I will have an JSON API that I use as my backend for a mobile and web app. It seems like good practice for both the mobile and web app to send along a token and secret so only these two apps can access the API blocking any other third party. But the mobile and web app allow users to login and submit posts, view their data, etc. So I would want them to login via HTTP Basic as well on each request. Do I somehow use a combination of both these methods or only send the end user credentials (username and token) on each request? If I only send the end user credentials, do I store them in a cookie on the client?

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  • Google suddenly only indexes https and not http

    - by spender
    So all of a sudden, searches for our site "radiotuna" give out the result as an HTTPS link. https://www.google.com/?q=radiotuna#hl=en&safe=off&output=search&sclient=psy-ab&q=radiotuna&oq=radiotuna&gs_l=hp.12...0.0.0.3499.0.0.0.0.0.0.0.0..0.0.les%3B..0.0...1c.LnOvBvgDOBk&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.&fp=177c7ff705652ec3&biw=1366&bih=602 We only use https for the download of two specific files (these urls are resources used for autoupdate functionality of an app we distribute). All other parts of the site should be served over http. We wouldn't like to see any other traffic over https, nor any of our site links to appear in search engines as https. I'd like to address this issue. It seems that the following solutions are available: hand out an https specific robots.txt as such: User-agent: * Disallow: / and/or at app-level, 301 permanent redirect all requests (except the two above) to HTTP if they come in as HTTPS. My concern with the robots method is that, say (for some reason) google decided not to index http pages, disallowing https pages might mean that google has nothing left to index with disastrous consequences for our ranking. This means I'm inclined to go with a 301 redirect. Any thoughts?

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  • How do I configure a C# web service client to send HTTP request header and body in parallel?

    - by Christopher
    Hi, I am using a traditional C# web service client generated in VS2008 .Net 3.5, inheriting from SoapHttpClientProtocol. This is connecting to a remote web service written in Java. All configuration is done in code during client initialization, and can be seen below: ServicePointManager.Expect100Continue = false; ServicePointManager.DefaultConnectionLimit = 10; var client = new APIService { EnableDecompression = true, Url = _url + "?guid=" + Guid.NewGuid(), Credentials = new NetworkCredential(user, password, null), PreAuthenticate = true, Timeout = 5000 // 5 sec }; It all works fine, but the time taken to execute the simplest method call is almost double the network ping time. Whereas a Java test client takes roughly the same as the network ping time: C# client ~ 550ms Java client ~ 340ms Network ping ~ 300ms After analyzing the TCP traffic for a session discovered the following: Basically, the C# client sent TCP packets in the following sequence. Client Send HTTP Headers in one packet. Client Waits For TCP ACK from server. Client Sends HTTP Body in one packet. Client Waits For TCP ACK from server. The Java client sent TCP packets in the following sequence. Client Sends HTTP Headers in one packet. Client Sends HTTP Body in one packet. Client Revieves ACK for first packet. Client Revieves ACK for second packet. Client Revieves ACK for second packet. Is there anyway to configure the C# web service client to send the header/body in parallel as the Java client appears to? Any help or pointers much appreciated.

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  • Is there a standard syntax for encoding structure objects as HTTP GET request parameters?

    - by lexicore
    Imagine we need to pass a a number structured objects to the web application - for instance, locale, layout settings and a definition of some query. This can be easily done with JSON or XML similar to the following fragment: <Locale>en</Locale> <Layout> <Block id="header">hide</Block> <Block id="footer">hide</Block> <Block id="navigation">minimize</Block> </Layout> <Query> <What>water</What> <When> <Start>2010-01-01</Start> </When> </Query> However, passing such structures with HTTP implies (roughly speaking) HTTP POST. Now assume we're limited to HTTP GET. Is there some kind of a standard solution for encoding structured data in HTTP GET request parameters? I can easily imagine something like: Locale=en& Layout.Block.header=hide& Layout.Block.footer=hide& Layout.Block.navigation=minimize& Query.What=water& Query.When.Start=2010-01-01 But what I'm looking for is a "standard" syntax, if there's any. ps. I'm surely aware of the problem with URL length. Please assume that it's not a problem in this case.

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  • HTTP POST with URL query parameters -- good idea or not?

    - by Steven Huwig
    I'm designing an API to go over HTTP and I am wondering if using the HTTP POST command, but with URL query parameters only and no request body, is a good way to go. Considerations: "Good Web design" requires non-idempotent actions to be sent via POST. This is a non-idempotent action. It is easier to develop and debug this app when the request parameters are present in the URL. The API is not intended for widespread use. It seems like making a POST request with no body will take a bit more work, e.g. a Content-Length: 0 header must be explicitly added. It also seems to me that a POST with no body is a bit counter to most developer's and HTTP frameworks' expectations. Are there any more pitfalls or advantages to sending parameters on a POST request via the URL query rather than the request body? Edit: The reason this is under consideration is that the operations are not idempotent and have side effects other than retrieval. See the HTTP spec: In particular, the convention has been established that the GET and HEAD methods SHOULD NOT have the significance of taking an action other than retrieval. These methods ought to be considered "safe". This allows user agents to represent other methods, such as POST, PUT and DELETE, in a special way, so that the user is made aware of the fact that a possibly unsafe action is being requested. ... Methods can also have the property of "idempotence" in that (aside from error or expiration issues) the side-effects of N 0 identical requests is the same as for a single request. The methods GET, HEAD, PUT and DELETE share this property. Also, the methods OPTIONS and TRACE SHOULD NOT have side effects, and so are inherently idempotent.

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  • Coldfusion 8 and HTTP PUT - is there a way to PUT an object?

    - by ciaranarcher
    Hi all We are using EHCache with CF 8 to cache stuff on a central server using a RESTful interface over HTTP. I am trying to cache a cfquery object to the cache server. I can get this to work if I call EHCache direct (i.e. store it in a local cache) but if I try to cache on a remote server over HTTP I am running into problems. The code I am using is as follows: <cfhttp url="http://localhost:8080/myCache/myKey" method="put" result="r" timeout="2" throwonerror="true" > <cfhttpparam type="body" value="#ARGUMENTS.item#" /> </cfhttp> CF doesn't like this reference to #ARGUMENTS.item# and it complains Complex object types cannot be converted to simple values. Can anyone give me an example of how to put an object over http using CF? If this is not possible with CF then a Java example would be the next best thing. Many thanks in advance! PS: I do not want to use serialization to text/JSON etc. as this approach has issues with data integrity and most importantly it's not fast enough.

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