Search Results

Search found 61530 results on 2462 pages for 'http header fields'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 37/2462 | < Previous Page | 33 34 35 36 37 38 39 40 41 42 43 44  | Next Page >

  • Http Requests POST vs GET

    - by behrk2
    Hi everyone, I am using a lot of HTTP Requests in an application that I am writing which uses OAuth. Currently, I am sending my GET and POST requests the same way: HttpConnection connection = (HttpConnection) Connector.open(url + connectionParameters); connection.setRequestMethod(method); connection.setRequestProperty("WWW-Authenticate", "OAuth realm=api.netflix.com"); int responseCode = connection.getResponseCode(); And this is working fine. I am successfully POSTing and GETing. However, I am worried that I am not doing POST the right way. Do I need to include in the above code the following if-statement? if (method.equals("POST") && postData != null) { connection.setRequestProperty("Content-type", "application/x-www-form-urlencoded"); connection.setRequestProperty("Content-Length", Integer .toString(postData.length)); OutputStream requestOutput = connection.openOutputStream(); requestOutput.write(postData); requestOutput.close(); } If so, why? What's the difference? I would appreciate any feedback. Thanks!

    Read the article

  • Android: Can not send http post

    - by jpartogi
    Hi all, I've been banging my head trying to figure out how to send a post method in Android. This is how my code look like: public class HomeActivity extends Activity implements OnClickListener { private TextView textView; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); textView = (TextView) findViewById(R.id.text); Button button = (Button)findViewById(R.id.button); button.setOnClickListener(this); } @Override public void onClick(View view) { HttpPost httpMethod = new HttpPost("http://www.example.com/"); httpMethod.addHeader("Accept", "text/html"); httpMethod.addHeader("Content-Type", "application/xml"); AndroidHttpClient client = AndroidHttpClient.newInstance("Android"); String result = null; try { HttpResponse response = client.execute(httpMethod); textView.setText(response.toString()); HttpEntity entity = response.getEntity(); Log.i(HomeActivity.class.toString(), result); textView.setText("Invoked webservice"); } catch (IOException e) { e.printStackTrace(); Log.e(HomeActivity.class.toString(), e.getMessage()); textView.setText("Something wrong:" + e.getMessage()); } } } What am I doing wrong here? Is there anything that I may need to configure from the Android emulator to get this working? Thank you for your help.

    Read the article

  • Java HTTP Requests Buffer size

    - by behrk2
    Hello, I have an HTTP Request Dispatcher class that works most of the time, but I had noticed that it "stalls" when receiving larger requests. After looking into the problem, I thought that perhaps I wasn't allocating enough bytes to the buffer. Before, I was doing: byte[] buffer = new byte[10000]; After changing it to 20000, it seems to have stopped stalling: String contentType = connection.getHeaderField("Content-type"); ByteArrayOutputStream baos = new ByteArrayOutputStream(); InputStream responseData = connection.openInputStream(); byte[] buffer = new byte[20000]; int bytesRead = responseData.read(buffer); while (bytesRead > 0) { baos.write(buffer, 0, bytesRead); bytesRead = responseData.read(buffer); } baos.close(); connection.close(); Am I doing this right? Is there anyway that I can dynamically set the number of bytes for the buffer based on the size of the request? Thanks...

    Read the article

  • Sharing session variables from http and https versio

    - by tangurena
    I am trying to fix an ASP.NET site that a friend had botched converting from older technologies. To the user, the site appears to have public and secured sections. Behind the scenes, the public and private sites are separate web applications with separate app pools. The difficulty arises because it appears that the applications share the same session IDs (when going from the public to the secured pages, the session ID remains the same), yet none of the (InProc) session variables are getting passed from the public site to the private one. Basically, the workflow consists of the user checking a checkbox ("I agree" type of stuff) on the public site (let's call that page http://www.boring.gov/iAgree.aspx), then logging in on the secured site (let's call that page https://www.boring.gov/login.aspx). The commandments from the parent agency in DC are that the user may not bookmark the login page, the user has to click "I agree" every time they log in, and that the "I agree" stuff has to be on a separate page. What am I missing? How would you do it? Notes: 1 - This is getting hosted on a single Windows 2003 server. 2 - Yes, it is a government agency. 3 - I would have done things very differently if I was doing the conversion, but I wasn't brought in until the poop hit the fan, and it is too late to redo things. 4 - Two previous SO threads that appear to be related, yet don't apply are this and that

    Read the article

  • Passing array values in an HTTP request in .NET

    - by Zarjay
    What's the standard way of passing and processing an array in an HTTP request in .NET? I have a solution, but I don't know if it's the best approach. Here's my solution: <form action="myhandler.ashx" method="post"> <input type="checkbox" name="user" value="Aaron" /> <input type="checkbox" name="user" value="Bobby" /> <input type="checkbox" name="user" value="Jimmy" /> <input type="checkbox" name="user" value="Kelly" /> <input type="checkbox" name="user" value="Simon" /> <input type="checkbox" name="user" value="TJ" /> <input type="submit" value="Submit" /> </form> The ASHX handler receives the "user" parameter as a comma-delimited string. You can get the values easily by splitting the string: public void ProcessRequest(HttpContext context) { string[] users = context.Request.Form["user"].Split(','); } So, I already have an answer to my problem: assign multiple values to the same parameter name, assume the ASHX handler receives it as a comma-delimited string, and split the string. My question is whether or not this is how it's typically done in .NET. What's the standard practice for this? Is there a simpler way to grab the multiple values than assuming that the value is comma-delimited and calling Split() on it? Is this how arrays are typically passed in .NET, or is XML used instead? Does anyone have any insight on whether or not this is the best approach?

    Read the article

  • How to handle building and parsing HTTP URL's / URI's / paths in Perl

    - by Robert S. Barnes
    I have a wget like script which downloads a page and then retrieves all the files linked in img tags on that page. Given the URL of the original page and the the link extracted from the img tag in that page I need to build the URL for the image file I want to retrieve. Currently I use a function I wrote: sub build_url { my ( $base, $path ) = @_; # if the path is absolute just prepend the domain to it if ($path =~ /^\//) { ($base) = $base =~ /^(?:http:\/\/)?(\w+(?:\.\w+)+)/; return "$base$path"; } my @base = split '/', $base; my @path = split '/', $path; # remove a trailing filename pop @base if $base =~ /[[:alnum:]]+\/[\w\d]+\.[\w]+$/; # check for relative paths my $relcount = $path =~ /(\.\.\/)/g; while ( $relcount-- ) { pop @base; shift @path; } return join '/', @base, @path; } The thing is, I'm surely not the first person solving this problem, and in fact it's such a general problem that I assume there must be some better, more standard way of dealing with it, using either a core module or something from CPAN - although via a core module is preferable. I was thinking about File::Spec but wasn't sure if it has all the functionality I would need.

    Read the article

  • Forwarding HTTP Request with Direct Server Return

    - by Daniel Crabtree
    I have servers spread across several data centers, each storing different files. I want users to be able to access the files on all servers through a single domain and have the individual servers return the files directly to the users. The following shows a simple example: 1) The user's browser requests http://www.example.com/files/file1.zip 2) Request goes to server A, based on the DNS A record for example.com. 3) Server A analyzes the request and works out that /files/file1.zip is stored on server B. 4) Server A forwards the request to server B. 5) Server B returns file1.zip directly to the user without going through server A. Note: steps 4 and 5 must be transparent to the user and cannot involve sending a redirect to the user as that would violate the requirement of a single domain. From my research, what I want to achieve is called "Direct Server Return" and it is a common setup for load balancing. It is also sometimes called a half reverse proxy. For step 4, it sounds like I need to do MAC Address Translation and then pass the request back onto the network and for servers outside the network of server A tunneling will be required. For step 5, I simply need to configure server B, as per the real servers in a load balancing setup. Namely, server B should have server A's IP address on the loopback interface and it should not answer any ARP requests for that IP address. My problem is how to actually achieve step 4? I have found plenty of hardware and software that can do this for simple load balancing at layer 4, but these solutions fall short and cannot handle the kind of custom routing I require. It seems like I will need to roll my own solution. Ideally, I would like to do the routing / forwarding at the web server level, i.e. in PHP or C# / ASP.net. However, I am open to doing it at a lower level such as Apache or IIS, or at an even lower level, i.e. a custom proxy service in front of everything.

    Read the article

  • C header file won't compile with C, but will with C++.

    - by Leif Andersen
    I have the following chunk of a header file BKE_mesh.h: /* Connectivity data */ typedef struct IndexNode { struct IndexNode *next, *prev; int index; } IndexNode; void create_vert_face_map(ListBase **map, IndexNode **mem, const struct MFace *mface, const int totvert, const int totface); void create_vert_edge_map(ListBase **map, IndexNode **mem, const struct MEdge *medge, const int totvert, const int totedge); Note that the header file was prepared for the possibility of being used in a C++ file, as it had: #ifdef __cplusplus extern "C" { #endif at the top of the file, and the needed finish at the bottom. But the class implementing it was written in C. Next, whenever I try to #include the header file, I get an odd error. If the file has a .cpp extension, it compiles just fine, no complaints whatsoever. However, if I do: #include "BKE_mesh.h" inside of a file with a .c extension, I get the following errors: expected ')' before '*' token for the two last functions, in specific, the variable: ListBase **map in both classes. (Note that earlier in the header file, it declared, but not defined ListBase). So, my question is: why is this valid C++ code, but not C code? Thank you.

    Read the article

  • Perl: Value of response code in HTTP::Request

    - by lola
    Hi all, So, I am writing a code to get a document from the internet. The document size is around 200 KB. This is the code: !/usr/local/bin/perl -w use strict; use LWP::UserAgent; my $ua = LWP::UserAgent->new; my $url = "SOME URL"; my $req = HTTP::Request->new(GET => $url); my $res = $ua->request($req); if($res->is_success){ print $res->content ."\n"; } else{ print "Error: " . $res->status_line; } Now, the only problem is I can't mention what the URL is. However, the output is: "Error: 500 read timeout". When I checked the link externally, the data is being downloaded in under 5 seconds. I even changed the timeout to 1000s, but it still didn't work. How should I go about finding more information related to the response. The size of the file (around 200KB) is also not too great to warrant a read timeout. The server is also not a busy one, didn't give a problem whenever I checked the link on the browser. Thanks.

    Read the article

  • Sending an HTTP POST request through the android emulator doesn't work

    - by Sotirios Delimanolis
    I'm running a tomcat servlet on my local machine and an Android emulator with an app that makes a post request to the servlet. The code for the POST is below (without exceptions and the like): String strUrl = "http://10.0.2.2:8080/DeviceDiscoveryServer/server/devices/"; Device device = Device.getUniqueInstance(); urlParameters += URLEncoder.encode("user", "UTF-8") + "=" + URLEncoder.encode(device.getUser(), "UTF-8"); urlParameters += "&" + URLEncoder.encode("port", "UTF-8") + "=" + URLEncoder.encode(new Integer(Device.PORT).toString(), "UTF-8"); urlParameters += "&" + URLEncoder.encode("address", "UTF-8") + "=" + URLEncoder.encode(device.getAddress().getHostAddress(), "UTF-8"); URL url = new URL(strUrl); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setDoOutput(true); connection.setRequestMethod("POST"); OutputStreamWriter wr = new OutputStreamWriter(connection.getOutputStream()); wr.write(urlParameters); wr.flush(); wr.close(); Whenever this code is executed, the servlet isn't called. However if I change the type of the request to 'GET' and don't write anything to the outputstream, the servlet gets called and everything works fine. Am I just not making the POST correctly or is there some other error?

    Read the article

  • Write transparent HTTP Proxy script in PHP

    - by Leo Izen
    Is there an easy forwarding/transparent php proxy script that I can host on my web server? These are my conditions: I'm using free web hosting, so I have pretty much no control over my machine. Otherwise I could use Perl's HTTP::Proxy module. This means no root password. It does run php though. I already have a server running on port 80. What I mean is I would like to put a php script as index.php on my server that will forward all requests. I don't want a script like PHProxy or Glype where I go to the site, then enter a URL. I want a server so I can enter proxy.example.com:80 in Firefox's or IE's or whatever's proxy settings and it will forward all requests to the server. Preferably (though not fatal if not possible) I would like for it to pass on the USER_AGENT environmental variable (That's the browser) instead of setting itself to be the USER_AGENT I can't start a new Daemon. My server won't allow it. Is there a script that will do this? If so, which?

    Read the article

  • Configuring Oracle HTTP Server 12c for WebLogic Server Domain

    - by Emin Askerov
    Oracle HTTP Server (OHS) 12c 12.1.2 which was released in July 2013 as a part of Oracle Web Tier 12c is the web server component of Oracle Fusion Middleware. In essence this is Apache HTTP Server 2.2.22 (with critical bug fixes from higher versions) which includes modules developed specifically by Oracle. It provides a listener functionality for Oracle WebLogic Server and the framework for hosting static pages, dynamic pages, and applications over the Web. OHS can be easily managed by Weblogic Management Framework, a set of tools which provides administrative capabilities (start, stop, lifecycle operations, etc.) for Oracle Fusion Middleware products. In other words all tools which are familiar to us (Node Manager, WLST, Administration Console, Fusion Middleware Control etc.) presented as a part of Weblogic Management Framework and using for managing Java and System Components both for Weblogic Server and Standalone Domain types. You can familiarize yourself with these terms using related documentation: 1. Introduction to Oracle HTTP Server: http://docs.oracle.com/middleware/1212/webtier/index.html 2. Weblogic Management Framework: http://docs.oracle.com/middleware/1212/core/ASCON/terminology.htm#ASCON11260 In the given post I would like to cover rather simple use case how to configure OHS as web proxy in Weblogic Cluster environment. For example, we have existing Weblogic Domain where some managed servers have been joined to cluster and host business applications. We need to configure web proxy component which will act as entry point, load balancer for our cluster for user requests. Of course, we could install old good Apache HTTP Server and configure mod_wl plugin. However this solution not optimal from manageability perspective: we need to install Apache, install additional plugin then configure it by editing configuration file which is not really convenient for FMW Administrators and often increase time of performing of simple administrative task. Alternatively, we could use OHS as System Component within Weblogic Domain and use full power of Weblogic Management Framework in order to configure, manage and monitor it! I like this idea! What about you? I hope after reading this post you will agree with me. First of all it is necessary to download OHS binaries. You can use this link for downloading: http://www.oracle.com/technetwork/java/webtier/downloads/index2-303202.html As we will use Fusion Middleware Control for managing OHS instances it is necessary to extend your domain with Enterprise Manager and Oracle ADF and JRF templates. This is not topic for focusing in this post, but you could get more information from documentation or one of my previous posts: http://docs.oracle.com/middleware/1212/wls/WLDTR/fmw_templates.htm#sthref64 https://blogs.oracle.com/imc/entry/the_specifics_of_adf_12c Note: you should have properly configured Node Manager utility for managing OHS instances Let’s consider configuration process step by step: 1. Shut down all Weblogic instances of existing domain including Admin Server; 2. Install Oracle HTTP Server. You should use your Fusion Middleware Home Path (e.g. /u01/Oracle/FMW12) for Installation Location and select Colocated HTTP Server option as Installation Type. I will not focus on this topic in this post. All information related to OHS installation you could find here: http://docs.oracle.com/middleware/1212/webtier/WTINS/install_gui.htm#i1082009 3. Next we need to extend our existing domain with OHS component. In order to do this you should do the following: a. Run Fusion Middleware Configuration Wizard (ORACLE_HOME/oracle_common/common/bin/config.sh); b. On the step 1 select Update an existing domain option and point your Fusion Middleware Home Path; c. On the step 2 check Oracle HTTP Server, Oracle Enterprise Manager Plugin for WEBTIER templates; d. Go through other steps without any changes and finish configuration process. 4. Start Admin Server and all managed servers related to your cluster 5. Log in to Enterprise Manager FMW Control using http://<hostname>:<port>/em URL 6. Now we will create OHS instance within our Weblogic Domain Infrastructure. Navigate to Weblogic Domain -> Administration -> Create/Delete OHS menu item; 7. Enter to edit mode, clicking Changes -> Lock&Edit menu item; 8. Create new OHS instance clicking Create button; 9. Define Instance Name (e.g. DevOSH) and Machine parameters; 10. Now we need to define listen port. By default OHS will use 7777 port number for income HTTP requests. We could change it to any free port number we would like to use. In order to do it, right click on our created OHS instance (left hand panel) and navigate to Administration -> Port Configuration; 11. Click on record with port number 7777 and then click Edit button; 12. Change port number value (in our case this will be 8080) and then click OK button; 13. Now we need to edit mod_wl_ohs configuration in order to enable OHS to act as proxy for WebLogic Server Instances/Cluster; 14. In order to do it right click on our created OHS instance (left panel) and navigate to Administration -> mod_wl_ohs Configuration; a. In Weblogic Cluster you should enter cluster address (define <host:port> for all managed servers which participated in cluster), e.g: 192.168.56.2:7004,192.168.56.2:7005 b. Define Weblogic Port parameter at which the Oracle WebLogic Server host is listening for connection requests from the module (or from other servers); c. Check Dynamic Server List option. This will dynamically update cluster list for every request; d. In the Location table define list of endpoint locations which you would like to process. In order to do this click Add Row button and define Location, Weblogic Cluster, Path Trim and Path Prefix parameters (if required); e. Click Apply button in order to save changes. 15. Activate changes clicking Changes ? Activate Changes menu item; 16. Finally we will start configured OHS instance. Right click on OHS instance tree item under Web Tier folder, select Control -> Start Up menu item; 17. Ensure that OHS instance up and running and then test your environment. Run deployed application to your Weblogic Cluster accessing via OHS web proxy; Normal 0 false false false RU X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}

    Read the article

  • Java HTTP Request Occasionally Hangs

    - by behrk2
    Hello Everyone, For the majority of the time, my HTTP Requests work with no problem. However, occasionally they will hang. The code that I am using is set up so that if the request succeeds (with a response code of 200 or 201), then call screen.requestSucceeded(). If the request fails, then call screen.requestFailed(). When the request hangs, however, it does so before one of the above methods are called. Is there something wrong with my code? Should I be using some sort of best practice to prevent any hanging? The following is my code. I would appreciate any help. Thanks! HttpConnection connection = (HttpConnection) Connector.open(url + connectionParameters); connection.setRequestMethod(method); connection.setRequestProperty("WWW-Authenticate", "OAuth realm=api.netflix.com"); if (method.equals("POST")) { connection.setRequestProperty("Content-type", "application/x-www-form-urlencoded"); } int responseCode = connection.getResponseCode(); System.out.println("RESPONSE CODE: " + responseCode); if (connection instanceof HttpsConnection) { HttpsConnection secureConnection = (HttpsConnection) connection; String issuer = secureConnection.getSecurityInfo() .getServerCertificate().getIssuer(); UiApplication.getUiApplication().invokeLater( new DialogRunner( "Secure Connection! Certificate issued by: " + issuer)); } if (responseCode != 200 && responseCode != 201) { screen.requestFailed("Unexpected response code: " + responseCode); connection.close(); return; } String contentType = connection.getHeaderField("Content-type"); ByteArrayOutputStream baos = new ByteArrayOutputStream(); InputStream responseData = connection.openInputStream(); byte[] buffer = new byte[20000]; int bytesRead = 0; while ((bytesRead = responseData.read(buffer)) > 0) { baos.write(buffer, 0, bytesRead); } baos.close(); connection.close(); screen.requestSucceeded(baos.toByteArray(), contentType); } catch (IOException ex) { screen.requestFailed(ex.toString()); }

    Read the article

  • Email Tracking - GMail

    - by Abs
    Hello all, I am creating my own email tracking system for email marketing tracking. I have been able to determine each persons email client they are using by using the http referrer but for some reason GMAIL does not send a HTTP_REFERRER at all! So I am trying to find another way of identifying when gmail requests a transparent image from my server. I get the following headers print_r($_SERVER);: DOCUMENT_ROOT = /usr/local/apache/htdocs GATEWAY_INTERFACE = CGI/1.1 HTTP_ACCEPT = */* HTTP_ACCEPT_CHARSET = ISO-8859-1,utf-8;q=0.7,*;q=0.3 HTTP_ACCEPT_ENCODING = gzip,deflate,sdch HTTP_ACCEPT_LANGUAGE = en-GB,en-US;q=0.8,en;q=0.6 HTTP_CONNECTION = keep-alive HTTP_COOKIE = __utmz=156230011.1290976484.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=156230011.422791272.1290976484.1293034866.1293050468.7 HTTP_HOST = xx.xxx.xx.xxx HTTP_USER_AGENT = Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.10 (KHTML, like Gecko) Chrome/8.0.552.237 Safari/534.10 PATH = /bin:/usr/bin QUERY_STRING = i=MTA= REDIRECT_STATUS = 200 REMOTE_ADDR = xx.xxx.xx.xxx REMOTE_PORT = 61296 REQUEST_METHOD = GET Is there anything of use in that list? Or is there something else I can do to actually get the http referrer, if not how are other ESPs managing to find whether gmail was used to view an email? Btw, I appreciate it if we can hold back on whether this is ethical or not as many ESPs do this already, I just don't want to pay for their service and I want to do it internally. Thanks all for any implementation advice. Update Just thought I would update this question and make it clearer in light of the bounty. I would like to find out when a user opens my email when sent to a GMail inbox. Assume, I have the usual transparent image tracking and the user does not block images. I would like to do this with the single request and the header details I get when the transparent image is requested.

    Read the article

  • How do I copy the layout from a header of a JTabbedPane onto a JPanel?

    - by Snail
    I have created a "CollapsingPanel"class/sort of a JTabbedPane (code skeleton can be found at http://www.coderanch.com/t/341737/Swing-AWT-SWT-JFace/java/Expand-Collapse-Panels). It is in other words a lot of headers which you click on to show a hidden Panel. At the moment these header-panels are a rectangular box with a LineBorder around them. That is ugly! I'm wondering if there is a way to copy the layout that the JTabbedPane uses for its headers/titles (which is inhierted from Look&Feel I assume) and use it on my JPanel-based headers? So that my headers get a smooth look which is in line with the rest of the program (based on Look&Feel!) instead of looking like alien flat blocks. Illustrated below with the headers nicely circled in green ;) I want to apply the header-look from 2nd picture over the red header JPanel in picture 1: Picture 1: hxxp://img7.imageshack.us/img7/2319/34158982.png - change to http, I got <10 rep :( Pictrue 2: hxxp://img46.imageshack.us/img46/2572/jtabpane.png

    Read the article

  • Haproxy not properly passing on X-Forwarded-For header

    - by JesseP
    I have backend web servers that receive requests by way of haproxy-nginx-fastcgi. The web app used to see multiple ip's coming through in the X-Forwarded-For header, chained together with commas (most original IP on the left). At some point in the recent past (just noticed, so not sure what caused it) something changed, and now I'm only seeing a single IP passed in the header to my web application. I've tried with haproxy 1.4.21 and 1.4.22 (recent upgrade) with the same behavior. Haproxy has the forwardfor header set: option forwardfor Nginx fastcgi_params config defines this header to be passed to the app: fastcgi_param HTTP_X_FORWARDED_FOR $http_x_forwarded_for; Anyone have any ideas on what might be going wrong here? EDIT: I just started logging the $http_x_forwarded_for variable in nginx logs, and nginx is only ever seeing a single IP, which shouldn't ever be the case, as we should always see our haproxy ip added in there, right? So, issue must either be in nginx handling of the variable coming in, or haproxy not building it properly. I'll keep digging... EDIT #2: I enabled request and response header logging in HAProxy, and it is not spitting anything out for X-Forwarded-For, which seems very odd: Oct 10 10:49:01 newark-lb1 haproxy[19989]: 66.87.95.74:47497 [10/Oct/2012:10:49:01.467] http service/newark2 0/0/0/16/40 301 574 - - ---- 4/4/3/0/0 0/0 {} {} "GET /2zi HTTP/1.1" O Here are the options i set for this in my frontend: mode http option httplog capture request header X-Forwarded-For len 25 capture response header X-Forwarded-For len 25 option httpclose option forwardfor EDIT #3: It really seems like haproxy is munging the header and just passing on a single one to the backend. This is fairly impacting to our production service, so if anyone has an ideas it would be greatly appreciated. I'm stumped... :(

    Read the article

  • How to set response header in JAX-RS so that user sees download popup for Excel?

    - by masato-san
    I wrote code that generate Excel file using REST JAX-RS and I confirmed that the generated Excel file is in GlassFish server directory. But my goal is when user click on the button (which generate Excel .xls), I want download popup to show up asking user whether to save or open the .xls file just like any other web services doing for downloading any type of files. According to my search, the step is: generate Excel .xls (DONE) write the excel to stream in JAX-RS file, set response header to something like, String fileName = "Blah_Report.xls"; response.setHeader("Content-Disposition", "attachment; filename=" + fileName); My question is I'm doing all of this in JAX-RS file and I don't have HttpServletResponse object available. According to the answer from Add Response Header to JAX-RS Webservice He says: You can inject a reference to the actual HttpServletResponse via the @Context annotation in your webservice and use addHeader() etc. to add your header. I can't really figure what exactly that means without sample code..

    Read the article

  • How to make g++ search for header files in a specific directory?

    - by Bane
    I have a project that is subdivided into a few directories with code in them. I'd like to to have g++ search for header files in the project's root directory, so I can avoid different include paths for same header files across multiple source files. Mainly, the root/ directory has sub-directories A/, B/ and C/, all of which have .hpp and .cpp files inside. If some source file in A wanted to include file.hpp, which was in B, it would have to do it like this: #include "../B/file.hpp". Same for another source file that was in C. But, if A itself had sub-directories with files that needed file.hpp, then, it would be inconsistent and would cause errors if I decided to move files (because the include path would be "../../B/file.hpp"). Also, this would need to work from other projects as well, which reside outside of root/. I already know that there is an option to manually copy all my header files into a default-search directory, but I'd like to do this the way I described.

    Read the article

  • Correct use of SMTP "Sender" header?

    - by Eric Rath
    Our web application sends email messages to people when someone posts new content. Both sender and recipient have opted into receiving email messages from our application. When preparing such a message, we set the following SMTP headers: FROM: [email protected] TO: [email protected] SENDER: [email protected] We chose to use the author's email address in the FROM header in an attempt to provide the best experience for the recipient; when they see the message in their mail client, the author is clear. To avoid the appearance of spoofing, we added the SENDER header (with our own company email address) to make it clear that we sent the message on the author's behalf. After reading RFCs 822 and 2822, this seems to be an intended use of the sender header. Most receiving mail servers seem to handle this well; the email message is delivered normally (assuming the recipient mailbox exists, is not over quota, etc). However, when sending a message FROM an address in a domain TO an address in the same domain, some receiving domains reject the messages with a response like: 571 incorrect IP - psmtp (in reply to RCPT TO command) I think this means the receiving server only saw that the FROM header address was in its own domain, and that the message originated from a server it didn't consider authorized to send messages for that domain. In other words, the receiving server ignored the SENDER header. We have a workaround in place: the webapp keeps a list of such domains that seem to ignore the SENDER header, and when the FROM and TO headers are both in such a domain, it sets the FROM header to our own email address instead. But this list requires maintenance. Is there a better way to achieve the desired experience? We'd like to be a "good citizen" of the net, and all parties involved -- senders and recipients -- want to participate and receive these messages. One alternative is to always use our company email address in the FROM header, and prepend the author's name/address to the subject, but this seems a little clumsy.

    Read the article

  • Correct use of SMTP "Sender" header?

    - by Eric Rath
    Our web application sends email messages to people when someone posts new content. Both sender and recipient have opted into receiving email messages from our application. When preparing such a message, we set the following SMTP headers: FROM: [email protected] TO: [email protected] SENDER: [email protected] We chose to use the author's email address in the FROM header in an attempt to provide the best experience for the recipient; when they see the message in their mail client, the author is clear. To avoid the appearance of spoofing, we added the SENDER header (with our own company email address) to make it clear that we sent the message on the author's behalf. After reading RFCs 822 and 2822, this seems to be an intended use of the sender header. Most receiving mail servers seem to handle this well; the email message is delivered normally (assuming the recipient mailbox exists, is not over quota, etc). However, when sending a message FROM an address in a domain TO an address in the same domain, some receiving domains reject the messages with a response like: 571 incorrect IP - psmtp (in reply to RCPT TO command) I think this means the receiving server only saw that the FROM header address was in its own domain, and that the message originated from a server it didn't consider authorized to send messages for that domain. In other words, the receiving server ignored the SENDER header. We have a workaround in place: the webapp keeps a list of such domains that seem to ignore the SENDER header, and when the FROM and TO headers are both in such a domain, it sets the FROM header to our own email address instead. But this list requires maintenance. Is there a better way to achieve the desired experience? We'd like to be a "good citizen" of the net, and all parties involved -- senders and recipients -- want to participate and receive these messages. One alternative is to always use our company email address in the FROM header, and prepend the author's name/address to the subject, but this seems a little clumsy.

    Read the article

  • Reverse-engineer SharePoint fields, content types and list instance—Part2

    - by ybbest
    Reverse-engineer SharePoint fields, content types and list instance—Part1 Reverse-engineer SharePoint fields, content types and list instance—Part2 In the part1 of this series, I demonstrated how to use VS2010 to Reverse-engineer SharePoint fields, content types and list instances. In the part 2 of this series, I will demonstrate how to do the same using CKS:Dev. CKS:Dev extends the Visual Studio 2010 SharePoint project system with advanced templates and tools. Using these extensions you will be able to find relevant information from your SharePoint environments without leaving Visual Studio. You will have greater productivity while developing SharePoint components and you will have greater deployment capabilities on your local SharePoint installation. You can download the complete solution here. 1. First, download and install appropriate CKS:Dev from CodePlex. If you are using SharePoint Foundation 2010 then download and install the SharePoint Foundation 2010 version If you are using SharePoint Server 2010 then download and install the SharePoint Server 2010 version 2. After installation, you need to restart your visual studio and create empty SharePoint. 3. Go to Viewà Server Explorer 4. Add SharePoint web application connection to the server explorer. 5. After add the connection, you can browse to see the contents for the Web Application. 6. Go to Site Columns à YBBEST (Custom Group of you own choice) and right-click the YBBEST Folder and Click Import Site Columns. 7. Go to ContentTypesà YBBEST (Custom Group of you own choice) and right-click the YBBEST Folder and Click Import Content Types. 8. After the import completes, you can find the fields and contentTypes in the SharePoint project below. Of course you need to do some modification to your current project to make it work. 9. Next, create list instances using list instance item template in Visual Studio 10. Finally, create lookup columns using the feature receivers and the final project will look like this. You can download the complete solution here.

    Read the article

  • A Taxonomy of Numerical Methods v1

    - by JoshReuben
    Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

    Read the article

  • An XEvent a Day (19 of 31) – Using Customizable Fields

    - by Jonathan Kehayias
    Today’s post will be somewhat short, but we’ll look at Customizable Fields on Events in Extended Events and how they are used to collect additional information.  Customizable Fields generally represent information of potential interest that may be expensive to collect, and is therefore made available for collection if specified by the Event Session.  In SQL Server 2008 and 2008 R2, there are 50 Events that have customizable columns in their payload.  In SQL Server Denali CTP1, there...(read more)

    Read the article

  • Concept of bit fields

    - by user1369975
    Whenever I read a code like this: struct node { int x : 2; int p : 4; }n; with bit fields involved, I get really confused, as to how they are represented in memory, what is sizeof(n) etc., how does it differ with normal members of structures? I tried referring K&R and http://en.wikipedia.org/wiki/Bit_field but they little to remove my confusion. What concepts of bit fields am I failing to grasp?

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 33 34 35 36 37 38 39 40 41 42 43 44  | Next Page >