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  • Message Passing Interface (MPI)

    So you have installed your cluster and you are done with introductory material on Windows HPC. Now you want to develop an application with the most common programming model: Message Passing Interface.The MPI programming model is a standard with implementations from many vendors. For newbies (like myself!), I have aggregated below links for getting started.Non-Microsoft MPI resources (useful even if you are not on the Windows platform)1. Message Passing Interface on wikipedia. 2. The MPI standard.3. MPICH2 - an MPI implementation.4. Tutorial on MPI by William Gropp.5. MPI patterns presented as a tutorial with sample code. 6. THE official MPI Forum (maintains the standard) including the wiki discussing the MPI future.7. Great MPI tutorial including at the end the MPI Exercise.8. C++ MPI Exercises by John Burkardt.9. Book online: MPI The Complete Reference.MS-MPI10. Windows HPC Server 2008 - Using MS-MPI whitepaper (15 page doc).11. Tracing MPI applications (27 page doc).12. Using Microsoft MPI (TechNet section).13. Windows HPC Server MPI forum (for posting questions). MPI.NET14. MPI.NET Home Page (not owned by Microsoft).15. MPI.NET Tutorial.16. HPC Development using F# using MPI.NET (38 page doc).Next time I'll post resources for the Microsoft Cluster SOA programming model - happy coding... Comments about this post welcome at the original blog.

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  • How to use shared_ptr for COM interface pointers

    - by Seefer
    I've been reading about various usage advice relating to the new c++ standard smart pointers unique_ptr, shared_ptr and weak_ptr and generally 'grok' what they are about when I'm writing my own code that declares and consumes them. However, all the discussions I've read seem restricted to this simple usage situation where the programmer is using smart in his/her own code, with no real discussion on techniques when having to work with libraries that expect raw pointers or other types of 'smart pointers' such as COM interface pointers. Specifically I'm learning my way through C++ by attempting to get a standard Win32 real-time game loop up and running that uses Direct2D & DirectWrite to render text to the display showing frames per second. My first task with Direct2D is in creating a Direct2D Factory object with the following code from the Direct2D examples on MSDN: ID2D1Factory* pD2DFactory = nullptr; HRESULT hr = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &pD2DFactory); pD2DFactory is obviously an 'out' parameter and it's here where I become uncertain how to make use of smart pointers in this context, if indeed it's possible. My inexperienced C++ mind tells me I have two problems: With pD2DFactory being a COM interface pointer type, how would smart_ptr work with the Add() / Release() member functions for a COM object instance? Are smart pointers able to be passed to functions in situations where the function is using an 'out' pointer parameter technique? I did experiment with the alternative of using _com_ptr_t in the comip.h header file to help with pointer lifetime management and declared the pD2DFactory pointer with the following code: _com_ptr_t<_com_IIID<pD2DFactory, &__uuidof(pD2DFactory)>> pD2DFactory = nullptr; and it appears to work so far but, as you can see, the syntax is cumbersome :) So, I was wondering if any C++ gurus here could confirm whether smart pointers are able to help in cases like this and provide examples of usage, or point me to more in-depth discussions of smart pointer usage when needing to work with other code libraries that know nothing of them. Or is it simply a case of my trying to use the wrong tool for the job? :)

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  • Is this a good way to expose generic base class methods through an interface?

    - by Nate Heinrich
    I am trying to provide an interface to an abstract generic base class. I want to have a method exposed on the interface that consumes the generic type, but whose implementation is ultimately handled by the classes that inherit from my abstract generic base. However I don't want the subclasses to have to downcast to work with the generic type (as they already know what the type should be). Here is a simple version of the only way I can see to get it to work at the moment. public interface IFoo { void Process(Bar_base bar); } public abstract class FooBase<T> : IFoo where T : Bar_base { abstract void Process(T bar); // Explicit IFoo Implementation void IFoo.Process(Bar_base bar) { if (bar == null) throw new ArgumentNullException(); // Downcast here in base class (less for subclasses to worry about) T downcasted_bar = bar as T; if (downcasted_bar == null) { throw new InvalidOperationException( string.Format("Expected type '{0}', not type '{1}'", T.ToString(), bar.GetType().ToString()); } //Process downcasted object. Process(downcasted_bar); } } Then subclasses of FooBase would look like this... public class Foo_impl1 : FooBase<Bar_impl1> { void override Process(Bar_impl1 bar) { //No need to downcast here! } } Obviously this won't provide me compile time Type Checking, but I think it will get the job done... Questions: 1. Will this function as I think it will? 2. Is this the best way to do this? 3. What are the issues with doing it this way? 4. Can you suggest a different approach? Thanks!

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  • Is there a way to make sure classes implementing an Interface implement static methods?

    - by Tobias Kienzler
    Frist of all, I read erickson's usefull reply to "Why can’t I define a static method in a Java interface?". This question is not about the "why" but about the "how then?". So basically I want one Interface to provide both usual methods and e.g. a getSimilarObject method. For (a made up) example public interface ParametricFunction { /** @return f(x) using the parameters */ static abstract public double getValue(double x, double[] parameters); /** @return The function's name */ static abstract public String getName(); } and then public class Parabola implements ParametricFunction { /** @return f(x) = parameters[0] * x² + parameters[1] * x + parameters[2] */ static public double getValue(double x, double[] parameters) { return ( parameters[2] + x*(parameters[1] + x*parameters[0])); } static public String getName() { return "Parabola"; } } Since this is not allowed in the current Java standard, what is the closest thing to this? The idea behind this is putting several ParametricFunction's in a package and use Reflection to list them all, allowing the user to pick e.g. which one to plot. Obviously one could provide a loader class containing an array of the available ParametricFunction's, but every time a new one is implemented one has to remember adding it there, too.

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  • c# Network Programming - HTTPWebRequest Scraping

    - by masterguru
    Hi, I am building a web scraping application. It should scrape a complex web site with concurrent HttpWebRequests from a single host to a single target web server. The application should run on Windows server 2008. One single HttpWebRequest for data could take from 1 minute to 4 minutes to complete (because of long running db operations) I should have at least 100 parallel requests to the target web server, but i have noticed that when i use more then 2-3 long-running requests i have big performance issues (request timeouts/hanging). How many concurrent requests can i have in this scenario from a single host to a single target web server? can i use Thread Pools in the application to run parallel HttpWebRequests to the server? will i have any issues with the default outbound HTTP connection/requests limits? what about Request timeouts when i reach outbound connection limits? what would be the best setup for my scenario? Any help would be appreciated. Thanks

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  • Are there some general Network programming best practices?

    - by uriDium
    I am implementing some networking stuff in our project. It has been decided that the communication is very important and we want to do it synchronously. So the client sends something the server acknowledges. Are there some general best practices for the interaction between the client and the server. For instance if there isn't an answer from the server should the client automatically retry? Should there be a timeout period before it retries? What happens if the acknowledgement fails? At what point do we break the connection and reconnect? Is there some material? I have done searches but nothing is really coming up. I am looking for best practices in general. I am implementing this in c# (probably with sockets) so if there is anything .Net specific then please let me know too.

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  • Calculation of charged traffic in GPRS network

    - by TyBoer
    I am working with a distributed application communicating over GPRS. I use UDP packets to send business data and ICMP pings to verify connectivity. And now I have a problem with calculating a traffic for which I will be charged by the provider. I have to consider following factors: UDP payload: that is obvious. UDP overhead: UDP header + IP header = 8 + 20 bytes. ICMP echo request without data: IP header + ICMP payload = 28 bytes. ICMP echo reply: as in 3. Above means that for evey data packet I am charged for payload + 28 bytes and for every ping 56 bytes. Am I right or I am missing/misunderstanding something?

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  • Social Network News Feed Database & Design

    - by pws5068
    I'm designing a News Feed system using PHP/MySQL similar to facebook's. I have asked a similar question before but now I've changed the design and I'm looking for feedback. Example Notifications: User_A commented on User_B's new album. "Hey man nice picture!" User_B added a new Photo to [his/her] profile. [show photo thumbnail] Initially, I implemented this using excessive columns for Obj1:Type1 | Obj2:Type2 | etc.. Now the design is set up using a couple special keywords, and actor/receiver relationships. My database is designed for efficiency - using a table of messages joined on a table containing userid,actionid,receiverid,receiverObjectTypeID, Here's a condensed version of what it will look like once joined: News_ID | User_ID | Message | Timestamp 2643 A %a commented on %o's new %r. SomeTimestamp 2644 B %a added a new %r to [his/her] profile. SomeTimestamp %a = the User_ID of the person doing the action %r = the receiving object %o = the owner of the receiving object (for example the owner of the album) (NULL if %r is a user) Questions: Is this a smart (efficient/scalable) way to move forward? How can I show messages like: "User_B added 4 new photos to his profile."?

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  • Neural Network: Handling unavailable inputs (missing or incomplete data)

    - by Mike
    Hopefully the last NN question you'll get from me this weekend, but here goes :) Is there a way to handle an input that you "don't always know"... so it doesn't affect the weightings somehow? Soo... if I ask someone if they are male or female and they would not like to answer, is there a way to disregard this input? Perhaps by placing it squarely in the centre? (assuming 1,0 inputs at 0.5?) Thanks

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  • Problem with a blocking network task

    - by user326967
    Hello everyone. I'm new in Java so please forgive any obscene errors that I may make :) I'm developing a program in Java that among other things it should also handle clients that will connect to a server. The server has 3 threads running, and I have created them in the following way : DaemonForUI du; DaemonForPort da; DaemonForCheck dc; da = new DaemonForPort(3); dc = new DaemonForCheck(5); du = new DaemonForUI(7); Thread t_port = new Thread(da); Thread t_check = new Thread(dc); Thread t_ui = new Thread(du); t_port.setName("v1.9--PORTd"); t_check.setName("v1.9-CHECKd"); t_ui.setName("v1.9----UId"); t_port.start(); t_check.start(); t_ui.start(); Each thread handles a different aspect of the complete program. The thread t_ui is responsible to accept asynchronous incoming connections from clients, process the sent data and send other data back to the client. When I remove all the commands from the previous piece of code that has to with the t_ui thread, everything runs ok which in my case means that the other threads are printing their debug messages. If I set the t_ui thread to run too, then the whole program blocks at the "accept" of the t_ui thread. After reading at online manuals I saw that the accepted connections should be non-blocking, therefore use something like that : public ServerSocketChannel ssc = null; ssc = ServerSocketChannel.open(); ssc.socket().bind(new InetSocketAddress(port)); ssc.configureBlocking(false); SocketChannel sc = ssc.accept(); if (sc == null) { ; } else { System.out.println("The server and client are connected!"); System.out.println("Incoming connection from: " + sc.socket().getRemoteSocketAddress()); in = new DataInputStream(new BufferedInputStream(sc.socket().getInputStream())); out = new DataOutputStream(new BufferedOutputStream(sc.socket().getOutputStream())); //other magic things take place after that point... The thread for t_ui is created as follows : class DaemonForUI implements Runnable{ private int cnt; private int rr; public ListenerForUI serverListener; public DaemonForUI(int rr){ cnt = 0; this.rr = rr; serverListener = new ListenerForUI(); } public static String getCurrentTime() { final String DATE_FORMAT_NOW = "yyyy-MM-dd HH:mm:ss"; Calendar cal = Calendar.getInstance(); SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW); return (sdf.format(cal.getTime())); } public void run() { while(true) { System.out.println(Thread.currentThread().getName() + "\t (" + cnt + ")\t (every " + rr + " sec) @ " + getCurrentTime()); try{ Thread.sleep(rr * 1000); cnt++; } catch (InterruptedException e){ e.printStackTrace(); } } } } Obviously, I'm doing something wrong at the creation of the socket or at the use of the thread. Do you know what is causing the problem? Every help would be greatly appreciated.

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  • How to gain greater control of network packets on Android

    - by mauvehead
    I'm looking to design an application that will require some deep control over IP packets. Looking over the reference guide on the developers site at Android I see very limited control over packets from java.net:SocketOptions and java.net:DatagramPacket. Specifically I'm looking to control the individual bits within the packet to set TCP Flags, SYN/ACK/RST, and so forth. Based on the docs I am assuming I cannot do this within the Java API provided by Android and I'm guessing I'll have to do it some other way? Anyone have any insight on this?

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  • Neural Network Basics

    - by Stat Onetwothree
    I'm a computer science student and for this years project, I need to create and apply a Genetic Algorithm to something. I think Neural Networks would be a good thing to apply it to, but I'm having trouble understanding them. I fully understand the concepts but none of the websites out there really explain the following which is blocking my understanding: How the decision is made for how many nodes there are. What the nodes actually represent and do. What part the weights and bias actually play in classification. Could someone please shed some light on this for me? Also, I'd really appreciate it if you have any similar ideas for what I could apply a GA to. Thanks very much! :)

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  • Hold a network connection although IP address change

    - by rursw1
    Hi, Is it possible to hold an open TCP connection with a client, while the IP address of the client is externally changed? For example, the connection is establishes against address X, but somewhen while the connection is open, the client-side user asks for IP renew and gets another IP address. Can the connection remains alive in this case? Thanks in advance.

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  • Neural Network: Handling unavailable inputs

    - by Mike
    Hopefully the last NN question you'll get from me this weekend, but here goes :) Is there a way to handle an input that you "don't always know"... so it doesn't affect the weightings somehow? Soo... if I ask someone if they are male or female and they would not like to answer, is there a way to disregard this input? Perhaps by placing it squarely in the centre? (assuming 1,0 inputs at 0.5?) Thanks

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  • Solution to route/proxy SNMP Traps (or Netflow, generic UDP, etc) for network monitoring?

    - by Christopher Cashell
    I'm implementing a network monitoring solution for a very large network (approximately 5000 network devices). We'd like to have all devices on our network send SNMP traps to a single box (technically this will probably be an HA pair of boxes) and then have that box pass the SNMP traps on to the real processing boxes. This will allow us to have multiple back-end boxes handling traps, and to distribute load among those back end boxes. One key feature that we need is the ability to forward the traps to a specific box depending on the source address of the trap. Any suggestions for the best way to handle this? Among the things we've considered are: Using snmptrapd to accept the traps, and have it pass them off to a custom written perl handler script to rewrite the trap and send it to the proper processing box Using some sort of load balancing software running on a Linux box to handle this (having some difficulty finding many load balancing programs that will handle UDP) Using a Load Balancing Appliance (F5, etc) Using IPTables on a Linux box to route the SNMP traps with NATing We've currently implemented and are testing the last solution, with a Linux box with IPTables configured to receive the traps, and then depending on the source address of the trap, rewrite it with a destination nat (DNAT) so the packet gets sent to the proper server. For example: # Range: 10.0.0.0/19 Site: abc01 Destination: foo01 iptables -t nat -A PREROUTING -p udp --dport 162 -s 10.0.0.0/19 -j DNAT --to-destination 10.1.2.3 # Range: 10.0.33.0/21 Site: abc01 Destination: foo01 iptables -t nat -A PREROUTING -p udp --dport 162 -s 10.0.33.0/21 -j DNAT --to-destination 10.1.2.3 # Range: 10.1.0.0/16 Site: xyz01 Destination: bar01 iptables -t nat -A PREROUTING -p udp --dport 162 -s 10.1.0.0/16 -j DNAT --to-destination 10.3.2.1 This should work with excellent efficiency for basic trap routing, but it leaves us completely limited to what we can mach and filter on with IPTables, so we're concerned about flexibility for the future. Another feature that we'd really like, but isn't quite a "must have" is the ability to duplicate or mirror the UDP packets. Being able to take one incoming trap and route it to multiple destinations would be very useful. Has anyone tried any of the possible solutions above for SNMP traps (or Netflow, general UDP, etc) load balancing? Or can anyone think of any other alternatives to solve this?

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  • How to connect the printer HP 2575 to a network?

    - by Peter
    I have 2 PCs and a router and I want to connect my HP 2575 to this network. So, I found a network cable and I connected the printer to the router. I access the router and I can see that the printer is connected. My question is: How can I use the printer, from one of my computer. I tried Add Printer feature, but with no luck. Any ideas?

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  • How do I map a network drive in Ubuntu? I want to save my Firefox downloads directly in the mapped n

    - by NJTechie
    I work in an environment wherein files are exchanged over email which are then processed into databases. In Windows, mapping a network drive and storing files directly to a folder in the network drive from Firefox/Chrome downloads is a breeze. How to achieve the same in Ubuntu? I don't see the SFTP'ed drive/directory as options in Firefox- Downloads setup. Thanks in advance!

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  • How do I map a network drive in Ubuntu? I want to save my Firefox downloads directly in the mapped n

    - by NJTechie
    I work in an environment wherein files are exchanged over email which are then processed into databases. In Windows, mapping a network drive and storing files directly to a folder in the network drive from Firefox/Chrome downloads is a breeze. How to achieve the same in Ubuntu? I don't see the SFTP'ed drive/directory as options in Firefox- Downloads setup. Thanks in advance!

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  • On a local network, are you able to password protect certain folders and how (in windows xp)?

    - by Derek
    I have a local network set up for my small office which consists of me, the manager, my wife, the secretary, and a few sales people/others. I would like to share passwords over the network and other such things privately to my wife, the secretary, but would not like the sales people and others to have access to it, yet I need the others to have access to other folders/documents that I'd like to share. How would I go about doing this if not by password? Thanks in advance

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