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  • Adaboost algorithm and its usage in face detection

    - by Hani
    I am trying to understand Adaboost algorithm but i have some troubles. After reading about Adaboost i realized that it is a classification algorithm(somehow like neural network). But i could not know how the weak classifiers are chosen (i think they are haar-like features for face detection) and how finally the H result which is the final strong classifier can be used. I mean if i found the alpha values and compute the H ,how am i going to benefit from it as a value (one or zero) for new images. Please is there an example describes it in a perfect way? i found the plus and minus example that is found in most adaboost tutorials but i did not know how exactly hi is chosen and how to adopt the same concept on face detection. I read many papers and i had many ideas but until now my ideas are not well arranged. Thanks....

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  • MySQL performance - 100Mb ethernet vs 1Gb ethernet

    - by Rob Penridge
    Hi All I've just started a new job and noticed that the analysts computers are connected to the network at 100Mbps. The ODBC queries we run against the MySQL server can easily return 500MB+ and it seems at times when the servers are under high load the DBAs kill low priority jobs as they are taking too long to run. My question is this... How much of this server time is spent executing the request, and how much time is spent returning the data to the client? Could the query speeds be improved by upgrading the network connections to 1Gbps? (Updated for the why): The database in question was built to accomodate reporting needs and contains massive amounts of data. We usually work with subsets of this data at a granular level in external applications such as SAS or Excel, hence the reason for the large amounts of data being transmitted. The queries are not poorly structured - they are very simple and the appropriate joins/indexes etc are being used. I've removed 'query' from the Title of the post as I realised this question is more to do with general MySQL performance rather than query related performance. I was kind of hoping that someone with a Gigabit connection may be able to actually quantify some results for me here by running a query that returns a decent amount of data, then they could limit their connection speed to 100Mb and rerun the same query. Hopefully this could be done in an environment where loads are reasonably stable so as not to skew the results. If ethernet speed can improve the situation I wanted some quantifiable results to help argue my case for upgrading the network connections. Thanks Rob

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  • Design for a machine learning artificial intelligence framework (community wiki)

    - by Lirik
    This is a community wiki which aims to provide a good design for a machine learning/artificial intelligence framework (ML/AI framework). Please contribute to the design of a language-agnostic framework which would allow multiple ML/AI algorithms to be plugged into a single framework which: runs the algorithms with a user-specified data set. facilitates learning, qualification, and classification. allows users to easily plug in new algorithms. can aggregate or create an ensemble of the existing algorithms. can save/load the progress of the algorithm (i.e. save the network and weights of a neural network, save the tree of a decision tree, etc.). What is a good design for this sort of ML/AI framework?

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  • Does SmtpClient class represent POP3 client or…?

    - by SourceC
    I assume that web controls (such as the PasswordRecovery control) use SmtpClient to send email messages. If so, does SmtpClient represent a POP3 client or does SmtpClient forward email message to POP3 client? Do attributes specified inside <smtp> element in web.config map to SmtpClient class? <system.net> <mailSettings> <smtp deliveryMethod="Network" ...></smtp> </mailSettings> </system.net> One of the possible values for the attribute deliveryMethod is Network, which tells that email should be sent through the network to an SMTP server. In other words, this value tells to send email to SMTP server using SMTP protocol?! For the PasswordRecovery control to be able to send email messages, we need to set basic properties in <MailDefinition> subelement of the PasswordRecovery control. Thus I assume MailDefinition is used by controls to create an email message?!

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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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  • ClickOnce Deployment Error - Access to the Path is Denied

    - by michael.lukatchik
    I have a WPF app that I'm deploying to a network path using ClickOnce deployment. After the app is deployed to a network location, I use the ClickOnce html page to launch the installation process. I am successfully able to download and install the app. However, my users are not able to download and install the app. When a user navigates to the ClickOnce html page and clicks to begin the installation process, the following error message is received: ERROR SUMMARY Below is a summary of the errors, details of these errors are listed later in the log. * Activation of http://software.mycompany.com/myapp/myapp.application resulted in exception. Following failure messages were detected: + Downloading file://dev/webs/software/myapp/myapp.application did not succeed. * [4/5/2010 1:56:59 PM] System.Deployment.Application.DeploymentDownloadException (Unknown subtype) - Downloading file://dev/Webs/software/myapp/myapp.application did not succeed. All signs point to this being a security issue. So, I've done the following: Ensured that "Everyone" had read access to the files that were being deployed as part of my project Ensured that "Everyone" had read access to the network location where the app was deployed (//dev/webs/software/myapp) Ensured that "Everyone" had read access to the IIS path where the ClickOnce html page is located In each of these cases, I've made no progress in getting the app to successfully deploy via ClickOnce. Again, the odd thing is that I am able to successfully walk through the process of downloading and installing the app. It's my users, though, that need the ability to download and install the app. I've looked extensively on the web for answers, but there hasn't been much. I'd like to resolve the issue without "re-installing" or "rigging" anything. I need a solid answer. Thank you all for your input!! Mike

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  • fabric deploy problem

    - by alexarsh
    Hi, I'm trying to deploy a django app with fabric and get the following error: Alexs-MacBook:fabric alex$ fab config:instance=peergw deploy -H <ip> - u <username> -p <password> [192.168.2.93] run: cat /etc/issue Traceback (most recent call last): File "build/bdist.macosx-10.6-universal/egg/fabric/main.py", line 419, in main File "/Users/alex/Rabota/server/mx30/scripts/fabric/fab/ commands.py", line 37, in deploy checkup() File "/Users/alex/Rabota/server/mx30/scripts/fabric/fab/ commands.py", line 140, in checkup if not 'Ubuntu' in run('cat /etc/issue'): File "build/bdist.macosx-10.6-universal/egg/fabric/network.py", line 382, in host_prompting_wrapper File "build/bdist.macosx-10.6-universal/egg/fabric/operations.py", line 414, in run File "build/bdist.macosx-10.6-universal/egg/fabric/network.py", line 65, in __getitem__ File "build/bdist.macosx-10.6-universal/egg/fabric/network.py", line 140, in connect File "build/bdist.macosx-10.6-universal/egg/paramiko/client.py", line 149, in load_system_host_keys File "build/bdist.macosx-10.6-universal/egg/paramiko/hostkeys.py", line 154, in load File "build/bdist.macosx-10.6-universal/egg/paramiko/hostkeys.py", line 66, in from_line File "build/bdist.macosx-10.6-universal/egg/paramiko/rsakey.py", line 61, in __init__ paramiko.SSHException: Invalid key Alexs-MacBook:fabric alex$ I can't connect to the server via ssh. What can be my problem? Regards, Arshavski Alexander.

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  • Is there an "embedded DBMS" to support multiple writer applications (processes) on the same db files

    - by Amir Moghimi
    I need to know if there is any embedded DBMS (preferably in Java and not necessarily relational) which supports multiple writer applications (processes) on the same set of db files. BerkeleyDB supports multiple readers but just one writer. I need multiple writers and multiple readers. UPDATE: It is not a multiple connection issue. I mean I do not need multiple connections to a running DBMS application (process) to write data. I need multiple DBMS applications (processes) to commit on the same storage files. HSQLDB, H2, JavaDB (Derby) and MongoDB do not support this feature. I think that there may be some File System limitations that prohibit this. If so, is there a File System that allows multiple writers on a single file? Use Case: The use case is a high-throughput clustered system that intends to store its high-volume business log entries into a SAN storage. Storing business logs in separate files for each server does not fit because query and indexing capabilities are needed on the whole biz logs. Because "a SAN typically is its own network of storage devices that are generally not accessible through the regular network by regular devices", I want to use SAN network bandwidth for logging while cluster LAN bandwidth is being used for other server to server and client to server communications.

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  • Calling unmanaged dll from C#. Take 2

    - by Charles Gargent
    I have written a c# program that calls a c++ dll that echoes the commandline args to a file When the c++ is called using the rundll32 command it displays the commandline args no problem, however when it is called from within the c# it doesnt. I asked this question to try and solve my problem, but I have modified it my test environment and I think it is worth asking a new question. Here is the c++ dll #include "stdafx.h" #include "stdlib.h" #include <stdio.h> #include <iostream> #include <fstream> using namespace std; BOOL APIENTRY DllMain( HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved ) { return TRUE; } extern "C" __declspec(dllexport) int WINAPI CMAKEX( HWND hwnd, HINSTANCE hinst, LPCSTR lpszCommandLine, DWORD dwReserved) { ofstream SaveFile("output.txt"); SaveFile << lpszCommandLine; SaveFile.close(); return 0; } Here is the c# app using System; using System.Collections.Generic; using System.Text; using System.Security.Cryptography; using System.Runtime.InteropServices; using System.Net; namespace nac { class Program { [DllImport("cmakca.dll", SetLastError = true, CharSet = CharSet.Unicode)] static extern bool CMAKEX(IntPtr hwnd, IntPtr hinst, string lpszCmdLine, int nCmdShow); static void Main(string[] args) { string cmdLine = @"/source_filename proxy-1.txt /backup_filename proxy.bak /DialRasEntry NULL /TunnelRasEntry DSLVPN /profile ""C:\Documents and Settings\Administrator\Application Data\Microsoft\Network\Connections\Cm\dslvpn.cmp"""; const int SW_SHOWNORMAL = 1; CMAKEX(IntPtr.Zero, IntPtr.Zero, cmdLine, SW_SHOWNORMAL).ToString(); } } } The output from the rundll32 command is rundll32 cmakex.dll,CMAKEX /source_filename proxy-1.txt /backup_filename proxy.bak /DialRasEntry NULL /TunnelRasEntry DSLVPN /profile ""C:\Documents and Settings\Administrator\Application Data\Microsoft\Network\Connections\Cm\dslvpn.cmp" /source_filename proxy-1.txt /backup_filename proxy.bak /DialRasEntry NULL /TunnelRasEntry DSLVPN /profile ""C:\Documents and Settings\Administrator\Application Data\Microsoft\Network\Connections\Cm\dslvpn.cmp" however the output when the c# app runs is /

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  • ASP.NET Chart Control errors in Event Viewer

    - by Richard Reddy
    Hi, I have been using the ASP.NET chart controls for a while on win2k3 (32bit) setups without any issue but have noticed that on our new win2k8 (64bit) box I am getting a warning message showing up in the event viewer from the chart control. In my web.config file I have the following tag telling the Chart Control where I can store the Temp Files: <add key="ChartImageHandler" value="storage=file;timeout=20;dir=c:\TempImageFiles\;" /> Below is the warning message produced by the control: Event code: 3005 Event message: An unhandled exception has occurred. Event time: 10/7/2009 2:40:03 PM Event time (UTC): 10/7/2009 2:40:03 PM Event ID: 237c3b208962429e8bbc5a48ffd177f0 Event sequence: 2860 Event occurrence: 26 Event detail code: 0 Application information: Application domain: /LM/W3SVC/2/ROOT-1-128993655360497729 Trust level: Full Application Virtual Path: / Application Path: C:\data\sites\mydomain.com\ Machine name: 231692-WEB Process information: Process ID: 4068 Process name: w3wp.exe Account name: NT AUTHORITY\NETWORK SERVICE Exception information: Exception type: ArgumentException Exception message: The image is not found. Request information: Request URL: http://www.mydomain.com/ChartImg.axd?i=chart%5F0%5F3.png&g=bccc8aa11abb470980c60e8cf1e71e15 Request path: /ChartImg.axd User host address: my domain ip User: Is authenticated: False Authentication Type: Thread account name: NT AUTHORITY\NETWORK SERVICE Thread information: Thread ID: 7 Thread account name: NT AUTHORITY\NETWORK SERVICE Is impersonating: False Stack trace: at System.Web.UI.DataVisualization.Charting.ChartHttpHandler.ProcessSavedChartImage(HttpContext context) at System.Web.UI.DataVisualization.Charting.ChartHttpHandler.System.Web.IHttpHandler.ProcessRequest(HttpContext context) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) It's worth pointing out that ALL of the chart images are displayed correctly on the screen so I'm not sure when/where the image not found error is being caused. Is this a 64bit issue? Thanks, Rich

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  • SqlException: User does not have permission to perform this action.

    - by Oskar Kjellin
    I have been using my website (ASP.NET MVC) in visual studio but now I want to host it on my server. I published from visual studio onto the network share to be used. The server is running Windows Home Server, IIS 6 and SQL Server 2008 R2 (express). In Microsoft SQL Server Management Studio, I've attached the database and made sure that the user IUSR_SERVER is owner of the db. I also made sure that the user Network Service has access. The Web Site is configured in IIS to run anonymously as IUSR_SERVER. I have granted write and read access to IUSR_SERVER as well as Network Service and made sure that nothing is read only. The web.config has this connectionstring: <connectionStrings> <remove name="ApplicationServices" /> <add name="ApplicationServices" connectionString="Data Source=.\SQLExpress;Integrated Security=True;Initial Catalog=MyDatebase" providerName="System.Data.SqlClient" /> </connectionStrings> However, I cannot browse my web site. I only get this error: Server Error in '/' Application. User does not have permission to perform this action. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: User does not have permission to perform this action. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [SqlException (0x80131904): User does not have permission to perform this action.] System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +4846887 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) +194 Feels like I've tried everything. Would be very grateful for your aid in this.

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  • Algorithm on trajectory analysis.

    - by Arman
    Hello, I would like to analyse the trajectory data based on given templates. I need to stack the similar trajectories together. The data is a set of coordinates xy,xy,xy and the templates are again the lines defined by the set of control points. I don't know to what direction to go, maybe to Neural Networks or pattern recognition? Could you please advace me page, book or library to start with? kind regards Arman. PS. Is it the right place to ask the question?

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  • Listener error not connecting

    - by Sham
    I have two database running on Port No : 1521. When i m connecting to ORCL db it get's connected, but when i try to connect to another DB it gives me following error. ORA-12514: TNS:listener does not currently know of service requested in connect descriptor. My Listener: # listener.ora Network Configuration File: C:\app\Administrator\product\11.2.0 \dbhome_1\network\admin\listener.ora # Generated by Oracle configuration tools. ADMIN_RESTRICTIONS_LISTENER = ON LISTENER = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 127.1.1.1)(PORT = 1521)) ) ) ADR_BASE_LISTENER = C:\app\Administrator TNSNAMES.ora ORCL = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 127.1.1.1)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl) ) ) PARIVARTAN = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 127.1.1.1)(PORT = 1521)) ) (CONNECT_DATA = (SERVICE_NAME = Parivartan) ) ) Lsnrctl Result STATUS of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for 64-bit Windows: Version 11.2.0.1.0 - Production Start Date 14-DEC-2012 14:22:51 Uptime 0 days 0 hr. 19 min. 31 sec Trace Level off Security ON: Local OS Authentication SNMP OFF Listener Parameter File C:\app\Administrator\product\11.2.0\dbhome_1\network\a dmin\listener.ora Listener Log File c:\app\administrator\diag\tnslsnr\127.1.1.1\listener\al ert\log.xml Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.1.1.1)(PORT=1521))) Services Summary... Service "orcl" has 1 instance(s). Instance "orcl", status READY, has 1 handler(s) for this service... Service "orclXDB" has 1 instance(s). Instance "orcl", status READY, has 1 handler(s) for this service... The command completed successfully Reply me soon....

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  • Can SOTI's MobiControl software interfere with an ASP.Net web service?

    - by MusiGenesis
    We have a set of WinMo (5.0) devices running a .NET CF application that talks to an ASP.Net web service running on a server. The devices connect to the network either via ActiveSync through a networked PC or directly to the network via an Ethernet dongle. In our development environment, the communication between devices and web service is 100% reliable. In our production environment, the communications are failing erratically and unpredictably. Sometimes calls to the web service (even to a simple test call that just returns a boolean) begin failing every time on a particular device, with the error message "Could not establish connection to network." This is usually fixed by flip-flopping the selected combo box values on the SETTINGS | NETWORKS screen. Sometimes calls on a particular device begin failing with a generic "WebException" message. The fix for this problem (so far) is either to reset the device (i.e. reinstall the OS) or else it just can't be fixed on some devices. To the best of our knowledge, everything about the DEV and PROD systems are the same (same server and device specs). The most obvious difference to us is that the PROD devices are all controlled by SOTI's MobiControl (which is server-side software that communicates with a SOTI client application installed on each device), whereas our DEV environment does not have SOTI installed anywhere (obviously we should have it there as well - long story). Does anybody have any experience with SOTI MobiControl and/or know of any documented problems where SOTI interferes with other communication mechanisms on a device?

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  • How to limit traffic using multicast over localhost

    - by Shane Holloway
    I'm using multicast UDP over localhost to implement a loose collection of cooperative programs running on a single machine. The following code works well on Mac OSX, Windows and linux. The flaw is that the code will receive UDP packets outside of the localhost network as well. For example, sendSock.sendto(pkt, ('192.168.0.25', 1600)) is received by my test machine when sent from another box on my network. import platform, time, socket, select addr = ("239.255.2.9", 1600) sendSock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP) sendSock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 24) sendSock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_IF, socket.inet_aton("127.0.0.1")) recvSock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP) recvSock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, True) if hasattr(socket, 'SO_REUSEPORT'): recvSock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, True) recvSock.bind(("0.0.0.0", addr[1])) status = recvSock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, socket.inet_aton(addr[0]) + socket.inet_aton("127.0.0.1")); while 1: pkt = "Hello host: {1} time: {0}".format(time.ctime(), platform.node()) print "SEND to: {0} data: {1}".format(addr, pkt) r = sendSock.sendto(pkt, addr) while select.select([recvSock], [], [], 0)[0]: data, fromAddr = recvSock.recvfrom(1024) print "RECV from: {0} data: {1}".format(fromAddr, data) time.sleep(2) I've attempted to recvSock.bind(("127.0.0.1", addr[1])), but that prevents the socket from receiving any multicast traffic. Is there a proper way to configure recvSock to only accept multicast packets from the 127/24 network, or do I need to test the address of each received packet?

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  • Scribe-LinkedIn Search API

    - by Rupeshit
    Hi folks, I want to fetch data from the LinkedIn API for that I am using the Scribe library.All requests are giving me data as expected but when I tried two facet in the url then scribe is not able to get data from LinkedIn API. If I gave this URL : http://api.linkedin.com/v1/people-search?facets=location,network&facet=location,in:0 then it gives me proper result but if I entered this URL: http://api.linkedin.com/v1/people-search?facets=location,network&facet=location,in:0&facet=network,F i.e. URL containing multiple facets then it gives me this output: <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <error> <status>401</status> <timestamp>1292487039516</timestamp> <error-code>0</error-code> <message> [unauthorized].OAU:CiEgwWDkA5BFpNrc0RfGyVuSlOh4tig5kOTZ9q97qcXNrFl7zqk- Ts7DqRGaKDCV|94f13544-9844-41eb-9d53-8fe36535bbc3|*01|*01:1292487039:VseHXaJXM2gerxJyn6kHhIka7zw=</message> </error> Any kind of help to solve this will be appreciated.Thanks.

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  • SqlBackup from my client app

    - by Robbert Dam
    I have an client app that runs on several machines, and connects to a single SQL database. On the client app, the user has the possiblity to use a local SQL (CE) database or connect to a remote SQL database. There is also a box where a backup location can be set. For the backup of the remote SQL database I use the following code: var bdi = new BackupDeviceItem(backupFile, DeviceType.File); var backup = new Backup { Database = "AppDb", Initialize = true }; backup.Devices.Add(bdi); var server = new Server(connection); backup.SqlBackup(server); When developing my application, I wasn't aware that the given backupFile is written on the machine where the SQL server runs! And not on the client machine. What I want is "dump" all the data from my database to a local file. (Why? Because users may enter a network location in the "backup location" box, and backing up SQL immediately to a network location fails. So need to write local first and then copy to the network in that case.) I there an alternative to the method above?

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  • Unable to connect on socket across different networks.

    - by maleki
    I am having trouble connecting my online application to others across another network. I am able to give them the hostAddress to connect when we are on the same network but when we are doing it across the internet the generated host address doesn't allow a connection, nor does using the ip address gotten from online sites such as whatismyip.com My biggest issue isn't debugging this code, because it works over intra-network but The server doesn't see attempts when we try to move to different networks. Also, the test ip I am using is 2222. InetAddress addr = InetAddress.getLocalHost(); String hostname = addr.getHostName(); System.out.println("Hostname: " + hostname); System.out.println("IP: " + addr.getHostAddress()); I display the host to the server when it is starting if (isClient) { System.out.println("Client Starting.."); clientSocket = new Socket(host, port_number); } else { System.out.println("Server Starting.."); echoServer = new ServerSocket(port_number); clientSocket = echoServer.accept(); System.out.println("Warning, Incoming Game.."); }

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  • Building a News-feed that comprises posts "created by user's connections" && "on the topics user is following"

    - by aklin81
    I am working on a project of Questions & Answers website that allows a user to follow questions on certain topics from his network. A user's news-feed wall comprises of only those questions that have been posted by his connections and tagged on the topics that he is following(his expertise topics). I am confused what database's datamodel would be most fitting for such an application. The project needs to consider the future provisions for scalability and high performance issues. I have been looking at Cassandra and MySQL solutions as of now. After my study of Cassandra I realized that Simple news-feed design that shows all the posts from network would be easy to design using Cassandra by executing fast writes to all followers of a user about the post from user. But for my kind of application where there is an additional filter of 'followed topics', (ie, the user receives posts "created by his network" && "on topics user is following"), I could not convince myself with a good schema design in Cassandra. I hope if I missed something because of my short understanding of cassandra, perhaps, can you please help me out with your suggestions of how this news-feed could be implemented in Cassandra ? Looking for a great project with Cassandra ! Edit: There are going to be maximum 5 tags allowed for tagging the question (ie, max 5 topics can be tagged on a question).

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  • Finding distance travelled by robot using Optical Flow

    - by user280454
    Hi, I'm working on a project right now in which we are developing an autonomous robot. I have to basically find out the distance travelled by the robot between any 2 intervals. I'm using OpenCV, and using the Optical Flow functions of OpenCV, I'm able to find out the velocity/distance of each pixel in 2 different images. Using this information, I want to be able to find out the distance travelled by the robot in the interval between those 2 images. I thought of a way in which we could develop an input output mapping between the distance travelled by pixels and the distance travelled by the bot (using some tests). In this way, using neural networks, we would be able to find the relationship. However, the optical flow would depend on the distance of the camera from the pixel, which would cause problems. Is there any way to solve this problem?

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  • Design Decision - Scaling out web based application's architecture

    - by Vadi
    This question is about design decision. I am currently working on a web project that will have 40K users to start with and in couple of month expected to grow 50M users (not concurrent users though). I would like to have a architecture that can be scaled out easily without much effort. In order to explain, I would like to use a trivial scenario. Lets say, User entities and services such as CreateUser, AuthenticateUser etc., are a simple method calls for the Page Controllers. But once the traffic increases, for example, authenticating user (or such services related to user entities) has to be moved out to a different internal server to spread the load. But at the same time using RPC calls over the network when the user count is 40K would become overkill. My proposal was to use IPC initially and when we need to scale out we can interally switch to TCP based RPC calls so that it can easily scale out. For example, I am referring to System.IO.Pipes.NamedPipeStreamServer to start with and move on to a TcpListener later on. If we have proper design that can encapsulate above said approach, it would easy for us to scale out services into multiple network servers but at the same time avoid network calls when the user count is small. Is this is a best approach? Any suggestions would be great .. Note: The database scaling is definetly the second phase optimization so we have already made architectural design in place to easily partition data when traffic increases. The primary bottleneck would be application servers over the time period.

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  • Strange File Upload issue with asp.net site on a web farm

    - by Coov
    I have a basic asp.net file upload page. When I test file uploads from my local machine, it works fine. When I test file uploads from our dev machine, it works fine. When I deploy the site to our production webfarm, it behaves strangely. If I access the site from off the network, I can load file-after-file without issue. If I access the site from within our network, I can load the first file just fine but any subsequent files result it a bad sequence of commands error. I'm not sure if this is web farm issue, a network issue, or something else. It feels like a connection is not being disposed of properly but it doesn't make sense why everything works fine remotely. Markup: <asp:FileUpload ID="FileUpload1" runat="server" Width="350px" /> <asp:Button ID="btnSubmit" runat="server" Text="Upload" onclick="btnSubmit_Click" /> Code: if (FileUpload1.HasFile) { FtpWebRequest ftpRequest; FtpWebResponse ftpResponse; ftpRequest = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://ftp.myftpsite.com/" + FileUpload1.FileName)); ftpRequest.Method = WebRequestMethods.Ftp.UploadFile; ftpRequest.Proxy = null; ftpRequest.UseBinary = true; ftpRequest.Credentials = new NetworkCredential("username", "password"); ftpRequest.KeepAlive = false; byte[] fileContents = new byte[FileUpload1.PostedFile.ContentLength]; using (Stream fr = FileUpload1.PostedFile.InputStream) { fr.Read(fileContents, 0, FileUpload1.PostedFile.ContentLength); } using (Stream writer = ftpRequest.GetRequestStream()) { writer.Write(fileContents, 0, fileContents.Length); } ftpResponse = (FtpWebResponse)ftpRequest.GetResponse(); Response.Write(ftpResponse.StatusDescription); }

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  • Essential skills of a Data Scientist

    - by harshsinghal
    I would like to know more about the relevant skills in the arsenal of a Data Scientist, and with new technologies coming in every day, how one picks and chooses the essentials. A few ideas germane to this discussion: Knowing SQL and the use of a DB such as MySQL, PostgreSQL was great till the advent of NoSql and non-relational databases. MongoDB, CouchDB etc. are becoming popular to work with web-scale data. Knowing a stats tool like R is enough for analysis, but to create applications one may need to add Java, Python, and such others to the list. Data now comes in the form of text, urls, multi-media to name a few, and there are different paradigms associated with their manipulation. What about cluster computing, parallel computing, the cloud, Amazon EC2, Hadoop ? OLS Regression now has Artificial Neural Networks, Random Forests and other relatively exotic machine learning/data mining algos. for company Thoughts?

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  • Cookie add in the Global.asax warning in application log

    - by Ioxp
    In my Global.ASAX file i have the following: System.Web.HttpCookie isAccess = new System.Web.HttpCookie("IsAccess"); isAccess.Expires = DateTime.Now.AddDays(-1); isAccess.Value = ""; System.Web.HttpContext.Current.Response.Cookies.Add(isAccess); So every time this method this is logged in the application events as a warning: Event code: 3005 Event message: An unhandled exception has occurred. Event time: 5/25/2010 12:23:20 PM Event time (UTC): 5/25/2010 4:23:20 PM Event ID: c515e27a28474eab8d99720c3f5a8e90 Event sequence: 4148 Event occurrence: 332 Event detail code: 0 Application information: Application domain: /LM/W3SVC/2100509645/Root-1-129192259222289896 Trust level: Full Application Virtual Path: / Application Path: <PathRemoved>\www\ Machine name: TIPPER Process information: Process ID: 6936 Process name: w3wp.exe Account name: NT AUTHORITY\NETWORK SERVICE Exception information: Exception type: NullReferenceException Exception message: Object reference not set to an instance of an object. Request information: Request URL: Request path: User host address: User: Is authenticated: False Authentication Type: Thread account name: NT AUTHORITY\NETWORK SERVICE Thread information: Thread ID: 7 Thread account name: NT AUTHORITY\NETWORK SERVICE Is impersonating: False Stack trace: at ASP.global_asax.Session_End(Object sender, EventArgs e) in <PathRemoved>\Global.asax:line 113 Any idea why this code would cause this error?

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  • NHibernate is not connecting to sql server.

    - by user177883
    When i set up a regular connection, it works, however when i try to use nhibernate, hibernate.cfg.xml, i m getting the following error. Message="A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)" Source=".Net SqlClient Data Provider" What would be the reason for this and how can i resolve it ? I doubt that it s a network or sql server configuration error. <?xml version="1.0" ?> <hibernate-configuration xmlns="urn:nhibernate-configuration-2.2" > <session-factory> <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property> <property name="dialect">NHibernate.Dialect.MsSql2005Dialect</property> <property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property> <property name="connection.connection_string">Server=(ServerName\DEV_ENV);Initial Catalog=dbName;User Id=SA;Password=PASS</property> <property name="proxyfactory.factory_class">NHibernate.ByteCode.LinFu.ProxyFactoryFactory, NHibernate.ByteCode.LinFu</property> </session-factory> </hibernate-configuration>

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