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• Detecting Connection Speed / Bandwidth in .net/WCF

  - by Mystagogue

  I'm writing both client and server code using WCF, where I need to know the "perceived" bandwidth of traffic between the client and server. I could use ping statistics to gather this information separately, but I wonder if there is a way to configure the channel stack in WCF so that the same statistics can be gathered simultaneously while performing my web service invocations. This would be particularly useful in cases where ICMP is disabled (e.g. ping won't work). In short, while making my regular business-related web service calls (REST calls to be precise), is there a way to collect connection speed data implicitly? Certainly I could time the web service round trip, compared to the size of data used in the round-trip, to give me an idea of throughput - but I won't know how much of that perceived bandwidth was network related, or simply due to server-processing latency. I could perhaps solve that by having the server send back a time delta, representing server latency, so that the client can compute the actual network traffic time. If a more sophisticated approach is not available, that might be my answer...

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• How to enable UAC prompt through programming

  - by peter

  I want to implement a UAC prompt for an application in visualc++ the operating system is 32bit x7460(2processor) Windowsserver 2008 the exe is myproject.exe through manifest.. Here for testing i wl build the application in Windows XP OS and copy the exe in to system containg the Windowsserver 2008 machine and replace it So what i did is i added a manifest like this name of that is myproject.exe.manifest My project has 3 folders like Headerfile,Resourcefile and Source file.I added this manifest(myproject.exe.manifest) in the Sourcefile folder containing other cpp and c code <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0"> <assemblyIdentity version="11.1.4.0" processorArchitecture="X7460" name="myproject" type="win32"/> <description>myproject Problem</description> <!-- Identify the application security requirements. --> <trustInfo xmlns="urn:schemas-microsoft-com:asm.v2"> <security> <requestedPrivileges> <requestedExecutionLevel level="requireAdministrator" uiAccess="false"/> </requestedPrivileges> </security> </trustInfo> </assembly> then i added this line of code in Resourcefile(.rc).Means one header file is there(Myproject.h).I added the line of code there #define MANIFEST_RESOURCE_ID 1 MANIFEST_RESOURCE_ID RT_MANIFEST "myproject.exe.manifest" Finally i did the following step 1. Open your project in Microsoft Visual Studio 2005. 2. Under Project, select Properties. 3. In Properties, select Manifest Tool, and then select Input and Output. 4. Add in the name of your application manifest file under Additional manifest files. 5. Rebuild your application. But i am getting lot of Syntax errors Is there any problems in the way which i followed.If i commented the line define MANIFEST_RESOURCE_ID 1 MANIFEST_RESOURCE_ID RT_MANIFEST "myproject.exe.manifest" which added in Myproject.h for adding values in .rc file there willnot any error other than this general error c1010070: Failed to load and parse the manifest. The system cannot find the file specified. .\myproject.exe.manifest How to enable UAC prompt through programming

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• Sending the array of arbitrary length through a socket. Endianness.

  - by Negai

  Hi everyone, I'm fighting with socket programming now and I've encountered a problem, which I don't know how to solve in a portable way. The task is simple : I need to send the array of 16 bytes over the network, receive it in a client application and parse it. I know, there are functions like htonl, htons and so one to use with uint16 and uint32. But what should I do with the chunks of data greater than that? Thank you.

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• Android, phone call audio stream via wlan

  - by moppel

  I am planning on developing my specific voip app for android. Here's the scenario: when a phone call occurs I want to hear the person who's calling on my local pc speakers and I want to speak to him via my own pc microphone / headset. So I need to send the audio stream of both me and the person I am talking to via the wlan network. Something like this: ... onCallStateChanged(int state, String phoneNumber){ while(state == PhoneListener.CALL_STATE_OFFHOOK){ //while phone call is happaning //send incoming speech via wlan to pc //receive audiostream from pc microphone and direct it to the phone call } } ... Is this possible with the current Android API? (Actually it should be since voip apps are available in the market) I did some research in the Android API and all I found was the AudioManager which has constant named public static final int STREAM_VOICE_CALL; //The audio stream for phone calls But I don't know how to use it our how it should give me access to the actual audiostreams which I can send via network. How do I manage to do this? The connection would be realised by TCP sockets.

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• Using Reachability for Internet *or* local WiFi?

  - by randallmeadows

  I've searched SO for the answer to this question, and it's not really addressed, at least not to a point where I can make it work. I was originally only checking for Internet reachability, using: self.wwanReach = [Reachability reachabilityWithHostName:@"www.apple.com"]; [wwanReach startNotifer]; I now need to support a local WiFi connection (in the absence of reaching the Internet in general), and when I found +reachabilityForLocalWiFi, I also noticed there was +reachabilityForInternetConnection. I figured I could use these, instead of hard-coding "www.apple.com" in there, but alas, when I use self.wwanReach = [Reachability reachabilityForInternetConnection]; [wwanReach startNotifer]; self.wifiReach = [Reachability reachabilityForLocalWiFi]; [wifiReach startNotifer]; the reachability callback that I've set up "never" gets called, for values of "never" up to 10, 12, 15 minutes or so (which was as long as my patience lasted. (User's patience will be much less, I'm sure.) Switching back to +reachabilityWithHostName: works within seconds. I also tried each "pair" individually, in case there was an issue with two notifiers in progress simultaneously, but that made no difference. So: what is the appropriate way to determine reachability to either the Internet/WWAN or a local Wifi network (either one, or both)? [This particular use case is an iPhone or iPad connecting to a Mac mini computer-to-computer network; I'm sure other situations apply.]

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• Need a fast programming language that can drive two printers

  - by Pete

  I have a rather unusual application that isn't working the way I need, and I hope someone here will have some suggestions or at least a direction to investigate. We have a museum exhibit that has a computer at the entrance driving two small receipt printers. There are two buttons on a console, wired to the left and right buttons of a disemboweled mouse. The two printers and associated buttons are for girls and boys, each button does a random selection from a database of names and prints a small ticket on the appropriate printer with a graphic image, a few words about the exhibit and the randomly chosen name. Conceptually all is well, but it hangs quite often. I got the project at the last minute, because the original designer got bogged down and couldn't deliver, so the exhibit's author asked me the day before opening, whether I could write something that would work. I did it in Word, since I am an experienced VBA programmer. Several other avenues I attempted first all lead to dead ends - one couldn't do graphics, another couldn't handle two printers, yet another couldn't change fonts and so on. The problem is that it simply isn't fast enough - Word can only drive one printer at a time and changing the active printer takes a long time. Not by office standards, where a second or two of delay before a printer starts working on your document is not an issue, but here I need more or less instant response. If kids press a button and nothing happens, they press it over and over until something does happen, resulting in maybe half a dozen commands being sent before the printer starts reacting. Sometimes it jams the program completely, since boys and girls will be pressing the two buttons simultaneously and Word locks up, and even when it doesn't jam, the printers then spit out a stream of tickets, making a mess. The kids start squabbling over which ticket is whose, pulling them out of the printers, snarling the paper tape, jamming the printer and generally making a mess of the whole affair, often necessitating the exhibit caretakers having to restart the computer and clear torn bits of paper out the printers. What I need is some sort of fast programming language that can drive two printers *-simultaneously-*, not the MSOffice claptrap of having to switch the active printer, that can react to both left and right mouse button click events, can print a small graphic image and can print in different font sizes and styles and. I don't need many, but it's not all in one typeface. Can anyone suggest what I might use for this? I don't even know if it's possible at all under Windows, whether the "single active printer" garbage is an Office artifact, or a Windows restriction. My little Commodore-64 twenty-five years ago had two printers attached to it and drove both simultaneously with no difficulties - it doesn't seem to me it should be such an impossible requirement today.

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• how to elegantly duplicate a graph (neural network)

  - by macias

  I have a graph (network) which consists of layers, which contains nodes (neurons). I would like to write a procedure to duplicate entire graph in most elegant way possible -- i.e. with minimal or no overhead added to the structure of the node or layer. Or yet in other words -- the procedure could be complex, but the complexity should not "leak" to structures. They should be no complex just because they are copyable. I wrote the code in C#, so far it looks like this: neuron has additional field -- copy_of which is pointer the the neuron which base copied from, this is my additional overhead neuron has parameterless method Clone() neuron has method Reconnect() -- which exchanges connection from "source" neuron (parameter) to "target" neuron (parameter) layer has parameterless method Clone() -- it simply call Clone() for all neurons network has parameterless method Clone() -- it calls Clone() for every layer and then it iterates over all neurons and creates mappings neuron=copy_of and then calls Reconnect to exchange all the "wiring" I hope my approach is clear. The question is -- is there more elegant method, I particularly don't like keeping extra pointer in neuron class just in case of being copied! I would like to gather the data in one point (network's Clone) and then dispose it completely (Clone method cannot have an argument though).

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• connecting to secure database on private network from website host

  - by jim

  Hello all, I've got a requirement to both read and write data via a .net webservice to a sqlserver database that's on a private network. this database is currently accessed via a vpn connection by remote client software (on standard desktop machines) to get latest product prices and to upload product stock sales. I've been tasked with finding a way to centralise this access from a webservice that the clients then access, rather than them using the vpn route to connect directly to the database. My question is related to my .net service's relationship to the sqlserver database. What are the options for connecting to a private network vpn from a domain host in order to achive the functionality of allowing the webservice to both read and write data to the database. For now, I'm not too concerned about the client connectivity and security (tho i appreciate that this will have to be worked out too), I'm really just interested in discovering the options available in order to allow my .net webservice to connect to the private network in as painless and transparent a way as posible. [edit] the webservice will also be available to the retail website in order for it to lookup product info as well as allocate stock transfers to the same sqlserver db. it will therefore be located on the same domain as the retail site The option of switching the database onto public hosting is not feasible, so I have to work with the scenario as described above for now, unless there's a compelling rationale presented to do otherwise. thanks all... jim

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• go programming POST FormValue can't be printed

  - by poor_programmer

  Before I being a bit of background, I am very new to go programming language. I am running go on Win 7, latest go package installer for windows. I'm not good at coding but I do like some challenge of learning a new language. I wanted to start learn Erlang but found go very interesting based on the GO I/O videos in youtube. I'm having problem with capturing POST form values in GO. I spend three hours yesterday to get go to print a POST form value in the browser and failed miserably. I don't know what I'm doing wrong, can anyone point me to the right direction? I can easily do this in another language like C#, PHP, VB, ASP, Rails etc. I have search the entire interweb and haven't found a working sample. Below is my sample code. Here is Index.html page {{ define "title" }}Homepage{{ end }} {{ define "content" }} <h1>My Homepage</h1> <p>Hello, and welcome to my homepage!</p> <form method="POST" action="/"> <p> Enter your name : <input type="text" name="username"> </P> <p> <button>Go</button> </form> <br /><br /> {{ end }} Here is the base page <!DOCTYPE html> <html lang="en"> <head> <title>{{ template "title" . }}</title> </head> <body> <section id="contents"> {{ template "content" . }} </section> <footer id="footer"> My homepage 2012 copy </footer> </body> </html> now some go code package main import ( "fmt" "http" "strings" "html/template" ) var index = template.Must(template.ParseFiles( "templates/_base.html", "templates/index.html", )) func GeneralHandler(w http.ResponseWriter, r *http.Request) { index.Execute(w, nil) if r.Method == "POST" { a := r.FormValue("username") fmt.Fprintf(w, "hi %s!",a); //<-- this variable does not rendered in the browser!!! } } func helloHandler(w http.ResponseWriter, r *http.Request) { remPartOfURL := r.URL.Path[len("/hello/"):] fmt.Fprintf(w, "Hello %s!", remPartOfURL) } func main() { http.HandleFunc("/", GeneralHandler) http.HandleFunc("/hello/", helloHandler) http.ListenAndServe("localhost:81", nil) } Thanks! PS: Very tedious to add four space before every line of code in stackoverflow especially when you are copy pasting. Didn't find it very user friendly or is there an easier way?

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• C: socket connection timeout

  - by The.Anti.9

  I have a simple program to check if a port is open, but I want to shorten the timeout length on the socket connection because the default is far too long. I'm not sure how to do this though. Here's the code: #include <sys/socket.h> #include <sys/time.h> #include <sys/types.h> #include <arpa/inet.h> #include <netinet/in.h> #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <netdb.h> #include <stdlib.h> #include <string.h> #include <unistd.h> int main(int argc, char **argv) { u_short port; /* user specified port number */ char addr[1023]; /* will be a copy of the address entered by u */ struct sockaddr_in address; /* the libc network address data structure */ short int sock = -1; /* file descriptor for the network socket */ if (argc != 3) { fprintf(stderr, "Usage %s <port_num> <address>", argv[0]); return EXIT_FAILURE; } address.sin_addr.s_addr = inet_addr(argv[2]); /* assign the address */ address.sin_port = htons(atoi(argv[2])); /* translate int2port num */ sock = socket(AF_INET, SOCK_STREAM, 0); if (connect(sock,(struct sockaddr *)&address,sizeof(address)) == 0) { printf("%i is open\n", port); } close(sock); return 0; }

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• Java: Multithreading & UDP Socket Programming

  - by Ravi

  I am new to multithreading & socket programming in Java. I would like to know what is the best way to implement 2 threads - one for receiving a socket and one for sending a socket. If what I am trying to do sounds absurd, pls let me know why! The code is largely inspired from Sun's tutorials online.I want to use Multicast sockets so that I can work with a multicast group. class server extends Thread { static protected MulticastSocket socket = null; protected BufferedReader in = null; public InetAddress group; private static class receive implements Runnable { public void run() { try { byte[] buf = new byte[256]; DatagramPacket pkt = new DatagramPacket(buf,buf.length); socket.receive(pkt); String received = new String(pkt.getData(),0,pkt.getLength()); System.out.println("From server@" + received); Thread.sleep(1000); } catch (IOException e) { System.out.println("Error:"+e); } catch (InterruptedException e) { System.out.println("Error:"+e); } } } public server() throws IOException { super("server"); socket = new MulticastSocket(4446); group = InetAddress.getByName("239.231.12.3"); socket.joinGroup(group); } public void run() { while(1>0) { try { byte[] buf = new byte[256]; DatagramPacket pkt = new DatagramPacket(buf,buf.length); //String msg = reader.readLine(); String pid = ManagementFactory.getRuntimeMXBean().getName(); buf = pid.getBytes(); pkt = new DatagramPacket(buf,buf.length,group,4446); socket.send(pkt); Thread t = new Thread(new receive()); t.start(); while(t.isAlive()) { t.join(1000); } sleep(1); } catch (IOException e) { System.out.println("Error:"+e); } catch (InterruptedException e) { System.out.println("Error:"+e); } } //socket.close(); } public static void main(String[] args) throws IOException { new server().start(); //System.out.println("Hello"); } }

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• Determine asymmetric latencies in a network

  - by BeeOnRope

  Imagine you have many clustered servers, across many hosts, in a heterogeneous network environment, such that the connections between servers may have wildly varying latencies and bandwidth. You want to build a map of the connections between servers my transferring data between them. Of course, this map may become stale over time as the network topology changes - but lets ignore those complexities for now and assume the network is relatively static. Given the latencies between nodes in this host graph, calculating the bandwidth is a relative simply timing exercise. I'm having more difficulty with the latencies - however. To get round-trip time, it is a simple matter of timing a return-trip ping from the local host to a remote host - both timing events (start, stop) occur on the local host. What if I want one-way times under the assumption that the latency is not equal in both directions? Assuming that the clocks on the various hosts are not precisely synchronized (at least that their error is of the the same magnitude as the latencies involved) - how can I calculate the one-way latency? In a related question - is this asymmetric latency (where a link is quicker in direction than the other) common in practice? For what reasons/hardware configurations? Certainly I'm aware of asymmetric bandwidth scenarios, especially on last-mile consumer links such as DSL and Cable, but I'm not so sure about latency. Added: After considering the comment below, the second portion of the question is probably better off on serverfault.

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• Are there any lightweight analogues to CORBA/RPC for embedded programs?

  - by Mtr

  I am writing embedded applications for different hardware (avr, arm7, tms55xx…) and different rtoses (freeRTOS, rtx, dsp/bios). And every second of them needs to communicate with PC or another digital device. Sometimes interactions logic is very advanced. So I'm interesting in common methodology (like state-machine programming style), protocol specification or library, that could simplify developing such things.

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• Raspberry Pi broadcast serial port data to local network

  - by D051P0

  I didn't find anything to help me with this problem. What I want is: Serial device sends repeatedly some data to serial port. Raspberry Pi should get this data from RxD and stream it to local network via port 10001 without filtering it. So I can find this device on my pc. This should also work in other direction: Raspberry listen to port 10001 and forward all data from local network to TxD. I'm newbie in Linux World. How can I listen to some port on Raspberry Pi and send broadcast to the same port? I'm using Raspbian Wheezy with soft float. I have found a library Pi4j for Java, that I already use to get and write data from/to serial port. final Serial serial = SerialFactory.createInstance(); serial.addListener(new SerialDataListener() { public void dataReceived(SerialDataEvent event) { forward(event.getData()); } }); event.getData() is a String, which I want to broadcast in my local network. Is it generally a good Idea to use Java for that? I need also a String from port 10001, which I can forward to serial port.

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• Guilty of unsound programming

  - by TelJanini

  I was reading Robert Rossney's entry on "What's the most unsound program you've had to maintain?" found at: (What's the most unsound program you've had to maintain?) when I realized that I had inadvertently developed a near-identical application! The app consists of an HTTPListener object that grabs incoming POST requests. Based on the information in the header, I pass the body of the request to SQL Server to perform the appropriate transaction. The requests look like: <InvoiceCreate Control="389> <Invoice> <CustomerNumber>5555</CustomerNumber> <Total>300.00</Total> <RushOrder>1</RushOrder> </Invoice> </InvoiceCreate> Once it's received by the HTTPListener object, I perform the required INSERT to the Invoice table using SQL Server's built-in XML handling functionality via a stored procedure: INSERT INTO Invoice (InvoiceNumber, CustomerNumber, Total, RushOrder) SELECT @NEW_INVOICE_NUMBER, @XML.value('(InvoiceCreate/Invoice/CustomerNumber)[1]', 'varchar(10)'), @XML.value('(InvoiceCreate/Invoice/Total)[1]', 'varchar(10)'), @XML.value('(InvoiceCreate/Invoice/Total)[1]', 'varchar(10)') I then use another SELECT statement in the same stored procedure to return the value of the new Invoice Number that was inserted into the Invoices table: SELECT @NEW_INVOICE_NUMBER FOR XML PATH 'InvoiceCreateAck' I then read the generated XML using a SQL data reader object in C# and use it as the response of the HTTPListener object. My issue is, I'm noticing that Robert is indeed correct. All of my application logic exists inside the stored procedure, so I find myself having to do a lot of error-checking (i.e. validating the customer number and invoicenumber values) inside the stored procedure. I'm still a midlevel developer, and as such, am looking to improve. Given the original post, and my current architecture, what could I have done differently to improve the application? Are there any patterns or best practices that I could refer to? What approach would you have taken? I'm open to any and all criticism, as I'd like to do my part to reduce the amount of "unsound programming" in the world.

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• In search of a network file system with extended caching to speed up file access

  - by Brecht Machiels

  I'm running a small home server that stores my documents. The disks in this server are in a RAID 1 configuration (using Linux md) and it's also periodically being backup up to an external hard drive to make sure I don't lose them. However, I'm always accessing the files from other computers on the home network using an SMB share, and this results in a considerable speed penalty (especially when connected over WLAN). This is quite annoying when editing large files, such as digital camera RAWs, for example. I've been looking for a solution to this problem. It would have to offer some kind of local caching to speed up the file access. The client would preferably not keep a copy of all data on the server, as it consists of a very large collection of photographs, most of which I will not access frequently. Instead, it should only cache the accessed files and sync the changes back in the background. Ideally, it would also do some smart read-ahead (cache the files that are in the same directory as the currently opened file, for examples), but I suppose that's asking a bit much. Synchronization should be automatic (on file change). Conflicting file changes (at the same time on different clients) are unlikely to happen in my use case, but I would prefer if they are handled properly (notification to the user). I've come across the following options, so far: something similar to Dropbox. iFolder seems to be the only thing that comes close, but its reputation (stability) and requirements put me off. A distributed file system such as OpenAFS. I'm not sure this will speed up file access. It is probably overkill for what I need. Maybe NFS or even Samba offer these possibilities. I read a bit about Windows' Offline Files, but its operation seems limited (at least on Windows XP). As this is just for personal use, I'm not willing to spend a lot of money. A free solution would be preferred. Also, the server needs to run on Linux, and I need a client for at least Windows.

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• KVM network bridge and public static IP for both host and guests

  - by Javier Martinez

  I have a Debian Server with 4 public static addresses. There is a KVM guest (also Debian) installed and running. What I want is to give the guest an IP of the host, so that both machines have public IPs. IP 1: 188.165.A.B IP 2: 178.33.CCC.D IP 3: 178.33.CCC.E IP 4: 178.33.CCC.F What should I do to have connection for host and guest ? This is network conf: # ifconfig br0 Link encap:Ethernet HWaddr e8:40:f2:0a:cc:28 inet addr:188.165.A.B Bcast:188.165.255.255 Mask:255.255.255.0 inet6 addr: fe80::ea40:f2ff:fe0a:cc28/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3618 errors:0 dropped:4 overruns:0 frame:0 TX packets:4853 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:599562 (585.5 KiB) TX bytes:1693443 (1.6 MiB) eth0 Link encap:Ethernet HWaddr e8:40:f2:0a:cc:28 inet6 addr: fe80::ea40:f2ff:fe0a:cc28/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:4274 errors:0 dropped:0 overruns:0 frame:0 TX packets:4879 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:720045 (703.1 KiB) TX bytes:1715641 (1.6 MiB) Interrupt:20 Memory:fe500000-fe520000 eth0:0 Link encap:Ethernet HWaddr e8:40:f2:0a:cc:28 inet addr:178.33.CCC.D Bcast:178.33.255.255 Mask:255.255.255.255 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Interrupt:20 Memory:fe500000-fe520000 eth0:1 Link encap:Ethernet HWaddr e8:40:f2:0a:cc:28 inet addr:178.33.CCC.E Bcast:178.33.255.255 Mask:255.255.255.255 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Interrupt:20 Memory:fe500000-fe520000 eth0:2 Link encap:Ethernet HWaddr e8:40:f2:0a:cc:28 inet addr:178.33.CCC.F Bcast:178.33.255.255 Mask:255.255.255.255 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Interrupt:20 Memory:fe500000-fe520000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:27932 errors:0 dropped:0 overruns:0 frame:0 TX packets:27932 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1820862 (1.7 MiB) TX bytes:1820862 (1.7 MiB) vnet0 Link encap:Ethernet HWaddr fe:54:00:87:40:ec inet6 addr: fe80::fc54:ff:fe87:40ec/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:18 errors:0 dropped:0 overruns:0 frame:0 TX packets:204 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:1452 (1.4 KiB) TX bytes:16958 (16.5 KiB) #route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default aa.bb.cc.eu 0.0.0.0 UG 0 0 0 br0 188.165.255.0 * 255.255.255.0 U 0 0 0 br0 # brctl show bridge name bridge id STP enabled interfaces br0 8000.e840f20acc28 no eth0 vnet0 There is no firewall enabled and DNS is configured properly. What I want to achieve: | | | +----+-------------------------+-+------+ | | Host | | | | | | | | | | +------------+------+ | | eth0 | eth0:0-1 | | | 188.165.A.B | | | | | | | | | br0 vnet0 | | | +------------+------+ | | | | | | | | +------------+------+ | | | | | | | | eth0:2-+ | | | | 178.33.CCC.F | | | | | | | | Guest | | | +-------------------+ | +---------------------------------------+ Thanks you

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• KVM network bridge and public static IP for both host and guests

  - by Javier Martinez

  I have a Debian Server with 4 public static addresses. There is a KVM guest (also Debian) installed and running. What I want is to give the guest an IP of the host, so that both machines have public IPs. IP 1: 188.165.A.B IP 2: 178.33.CCC.D IP 3: 178.33.CCC.E IP 4: 178.33.CCC.F What should I do to have connection for host and guest ? This is network conf: # ifconfig br0 Link encap:Ethernet HWaddr e8:40:f2:0a:cc:28 inet addr:188.165.A.B Bcast:188.165.255.255 Mask:255.255.255.0 inet6 addr: fe80::ea40:f2ff:fe0a:cc28/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3618 errors:0 dropped:4 overruns:0 frame:0 TX packets:4853 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:599562 (585.5 KiB) TX bytes:1693443 (1.6 MiB) eth0 Link encap:Ethernet HWaddr e8:40:f2:0a:cc:28 inet6 addr: fe80::ea40:f2ff:fe0a:cc28/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:4274 errors:0 dropped:0 overruns:0 frame:0 TX packets:4879 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:720045 (703.1 KiB) TX bytes:1715641 (1.6 MiB) Interrupt:20 Memory:fe500000-fe520000 eth0:0 Link encap:Ethernet HWaddr e8:40:f2:0a:cc:28 inet addr:178.33.CCC.D Bcast:178.33.255.255 Mask:255.255.255.255 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Interrupt:20 Memory:fe500000-fe520000 eth0:1 Link encap:Ethernet HWaddr e8:40:f2:0a:cc:28 inet addr:178.33.CCC.E Bcast:178.33.255.255 Mask:255.255.255.255 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Interrupt:20 Memory:fe500000-fe520000 eth0:2 Link encap:Ethernet HWaddr e8:40:f2:0a:cc:28 inet addr:178.33.CCC.F Bcast:178.33.255.255 Mask:255.255.255.255 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Interrupt:20 Memory:fe500000-fe520000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:27932 errors:0 dropped:0 overruns:0 frame:0 TX packets:27932 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1820862 (1.7 MiB) TX bytes:1820862 (1.7 MiB) vnet0 Link encap:Ethernet HWaddr fe:54:00:87:40:ec inet6 addr: fe80::fc54:ff:fe87:40ec/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:18 errors:0 dropped:0 overruns:0 frame:0 TX packets:204 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:1452 (1.4 KiB) TX bytes:16958 (16.5 KiB) #route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default aa.bb.cc.eu 0.0.0.0 UG 0 0 0 br0 188.165.255.0 * 255.255.255.0 U 0 0 0 br0 # brctl show bridge name bridge id STP enabled interfaces br0 8000.e840f20acc28 no eth0 vnet0 There is no firewall enabled and DNS is configured properly. What I want to achieve: | | | +----+-------------------------+-+------+ | | Host | | | | | | | | | | +------------+------+ | | eth0 | eth0:0-1 | | | 188.165.A.B | | | | | | | | | br0 vnet0 | | | +------------+------+ | | | | | | | | +------------+------+ | | | | | | | | eth0:2-+ | | | | 178.33.CCC.F | | | | | | | | Guest | | | +-------------------+ | +---------------------------------------+ Thanks you

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• Conflicting ip routes with local table on attaching a virtual network interface

  - by user1071840

  I have an EC2 instance with these ip rules: $ sudo ip rule show 0: from all lookup local 32766: from all lookup main 32767: from all lookup default I can attach an elastic network interface to it with a private IP. Say the IP of my machine is 10.1.3.12 and the IP of the interface is 10.1.1.190. As soon as I attach the interface to my machine a new entry is added to the routing policy and local routing table: sudo ip rule show 0: from all lookup local 32765: from 10.1.1.190 lookup 10003 32766: from all lookup main 32767: from all lookup default $ sudo ip route show table local broadcast 10.1.1.0 dev eth3 proto kernel scope link src 10.1.1.190 local 10.1.1.190 dev eth3 proto kernel scope host src 10.1.1.190 broadcast 10.1.1.255 dev eth3 proto kernel scope link src 10.1.1.190 broadcast 10.1.3.0 dev eth0 proto kernel scope link src 10.1.3.12 local 10.1.3.12 dev eth0 proto kernel scope host src 10.1.3.12 broadcast 10.1.3.255 dev eth0 proto kernel scope link src 10.1.3.12 broadcast 127.0.0.0 dev lo proto kernel scope link src 127.0.0.1 local 127.0.0.0/8 dev lo proto kernel scope host src 127.0.0.1 local 127.0.0.1 dev lo proto kernel scope host src 127.0.0.1 broadcast 127.255.255.255 dev lo proto kernel scope link src 127.0.0.1 I can send traffic to this ENI directly from a host that can have the same IP as the host the ENI is attached to. This is where the problem starts. I ran tcpdump on the port in question and saw multiple SYNs going to the ENI with src '10.1.3.12' and destination '10.1.1.190' but didn't see even a single ACK. In my understanding if ACKs were being sent from the ENI they'd have destination as 10.1.3.12 i.e. the same as the local machine's IP and such packets will now be routed as local packets matching local routing policy: local 10.1.3.12 dev eth0 proto kernel scope host src 10.1.3.12 I'd like to send all the packets originating from 10.1.1.190 (my ENI) to go back on the same interface i.e. eth3 in this case. Contents of the nee table 10003 are: $ sudo ip route show table 10003 default via 10.1.1.1 dev eth3 I think I can do the following: I don't know if its possible but probably decrease the priority of local table so the packets match the table 10003. Use iptables to mangle these packets and update the local table route to include the mark information But I'm not sure if these are the right approaches.

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• Configure server on network to analyze traffic

  - by Strajan Sebastian

  I have the following network: http://i.stack.imgur.com/rapkH.jpg I want to send all the traffic from the devices that connect to the 192.168.0.1 router to the 192.168.10.1 router(and eventually to the Internet), by passing through the server and an additional router. Almost 2 days have passed and I can't figure what is wrong. While searching on the Internet for some similar configuration I found some articles that are somehow related to my needs, but the proposed solutions don't seem to work for me. This is a similar article: iptables forwarding between two interface I done the following steps for the configuration process: Set static IP address 192.168.1.90 for the eth0 on the server from the 192.168.1.1 router Set static IP address 192.168.0.90 for the eth1 on the server from the 192.168.0.1 router Forwarded all the traffic from 192.168.0.1 router to the server on eth1 interface witch seems to be working. The router firmware has some option to redirect all the traffic from all the ports to a specified address. Added the following rules on the server(Only the following, there aren't any additional rules): iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE iptables -A FORWARD -i eth1 -o eth0 -m state -–state RELATED,ESTABLISHED -j ACCEPT iptables -A FORWARD -i eth0 -o eth1 -j ACCEPT I also tried changing iptables -A FORWARD -i eth1 -o eth0 -m state -–state RELATED,ESTABLISHED -j ACCEPT into iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT but still is not working. After adding the following to enable the packet forwarding for the server that is running CentOS: echo 1 /proc/sys/net/ipv4/ip_forward sysctl -w net.ipv4.ip_forward = 1 After a server restart and extra an extra check to see that all the configuration from above are still available I tried to see again if I can ping from a computer connected to 192.168.0.1/24 LAN the router from 192.168.1.1 but it didn't worked. The server has tshark(console wireshark) installed and I found that while sending a ping from a computer connected to 192.168.0.1 router to 192.168.1.1 the 192.168.0.90(eth1) receives the ping but it doesn't forward it to the eth0 interface as the rule tells: iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT and don't now why this is happening. Questions: The iptables seem that don't work as I am expecting. Is there a need to add in the NAT table from iptables rules to redirect the traffic to the proper location, or is something else wrong with what I've done? I want to use tshark to view the traffic on the server because I think that is the best at doing this. Do you know something better that tshark to capture the traffic and maybe analyze it?

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• Windows CE Programming Serial Port - Getting Garbled Output

  - by user576639

  I am programming a Windows CE 6 device (Motorola MC3100 scanner Terminal). Using Lazarus FPC to compile it. After 3 weeks work I reluctantly post here in the hope someone can suggest why I am getting garbled output from the serial port. The code I am using is posted below. This is the standard code I have found from several places. The OpenPort works OK. When I send the string using SendString('ABCDEF') I get garbled input to the PC Serial port such as: 4[#131][#26][#0][#0][#0][#0] (the bracketed data indicates that it is a non-printable character ASCII Code) Obviously it is connecting to the port OK AND it is sending the correct no of characters (7). I have tried all combinations of Baud Rate, Data Bits, Parity and Stop Bits without any joy. Also tried changing cable, on a different PC etc. Could it be I need to set something else in the DCB? Any help or suggestions would be GREATLY appreciated. unit Unit1; {$mode objfpc}{$H+} interface uses Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls, ExtCtrls, Windows, LResources; type { TForm1 } TForm1 = class(TForm) Button1: TButton; Button2: TButton; Label1: TLabel; procedure Button1Click(Sender: TObject); procedure Button2Click(Sender: TObject); function OpenPort(ComPort:String;BaudRate,ByteSize,Parity,StopBits:integer):String; procedure SendString(str:String); private { private declarations } public { public declarations } end; var Form1: TForm1; cc:TCOMMCONFIG; Connected:Boolean; implementation {$R *.lfm} var F: TextFile; var hComm: THandle; str: String; lrc: LongWord; { TForm1 } function OpenPort(ComPort:String;BaudRate,ByteSize,Parity,StopBits:integer):String; var cc:TCOMMCONFIG; SWide:WideString; Port:LPCWSTR; begin SWide:=ComPort; Port:=PWideChar(SWide); result:=''; if (1=1) then begin Connected:=False; hComm:=CreateFile(Port, GENERIC_READ or GENERIC_WRITE,0, nil,OPEN_EXISTING,0,0); if (hComm = INVALID_HANDLE_VALUE) then begin ShowMessage('Fail to Open'); exit; end; GetCommState(hComm,cc.dcb); cc.dcb.BaudRate:=BaudRate; cc.dcb.ByteSize:=ByteSize; cc.dcb.Parity:=Parity; cc.dcb.StopBits:=StopBits; if not SetCommState(hComm, cc.dcb) then begin result:='SetCommState Error!'; CloseHandle(hComm); exit; end; Connected:=True; end; end; procedure TForm1.Button1Click(Sender: TObject); begin OpenPort('COM1:',9600,8,0,0); end; procedure TForm1.Button2Click(Sender: TObject); begin SendString('ABCDEFG'); end; procedure TForm1.SendString(str:String); var lrc:LongWord; begin if (hComm=0) then exit; try if not PurgeComm(hComm, PURGE_TXABORT or PURGE_TXCLEAR) then raise Exception.Create('Unable to purge com: '); except Exit; end; WriteFile(hComm,str,Length(str), lrc, nil); end; end.

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• SqlBulkCopy is slow, doesn't utilize full network speed

  - by Alex

  Hi, for that past couple of weeks I have been creating generic script that is able to copy databases. The goal is to be able to specify any database on some server and copy it to some other location, and it should only copy the specified content. The exact content to be copied over is specified in a configuration file. This script is going to be used on some 10 different databases and run weekly. And in the end we are copying only about 3%-20% of databases which are as large as 500GB. I have been using the SMO assemblies to achieve this. This is my first time working with SMO and it took a while to create generic way to copy the schema objects, filegroups ...etc. (Actually helped find some bad stored procs). Overall I have a working script which is lacking on performance (and at times times out) and was hoping you guys would be able to help. When executing the WriteToServer command to copy large amount of data ( 6GB) it reaches my timeout period of 1hr. Here is the core code for copying table data. The script is written in PowerShell. $query = ("SELECT * FROM $selectedTable " + $global:selectiveTables.Get_Item($selectedTable)).Trim() Write-LogOutput "Copying $selectedTable : '$query'" $cmd = New-Object Data.SqlClient.SqlCommand -argumentList $query, $source $cmd.CommandTimeout = 120; $bulkData = ([Data.SqlClient.SqlBulkCopy]$destination) $bulkData.DestinationTableName = $selectedTable; $bulkData.BulkCopyTimeout = $global:tableCopyDataTimeout # = 3600 $reader = $cmd.ExecuteReader(); $bulkData.WriteToServer($reader); # Takes forever here on large tables The source and target databases are located on different servers so I kept track of the network speed as well. The network utilization never went over 1% which was quite surprising to me. But when I just transfer some large files between the servers, the network utilization spikes up to 10%. I have tried setting the $bulkData.BatchSize to 5000 but nothing really changed. Increasing the BulkCopyTimeout to an even greater amount would only solve the timeout. I really would like to know why the network is not being used fully. Anyone else had this problem? Any suggestions on networking or bulk copy will be appreciated. And please let me know if you need more information. Thanks. UPDATE I have tweaked several options that increase the performance of SqlBulkCopy, such as setting the transaction logging to simple and providing a table lock to SqlBulkCopy instead of the default row lock. Also some tables are better optimized for certain batch sizes. Overall, the duration of the copy was decreased by some 15%. And what we will do is execute the copy of each database simultaneously on different servers. But I am still having a timeout issue when copying one of the databases. When copying one of the larger databases, there is a table for which I consistently get the following exception: System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. It is thrown about 16 after it starts copying the table which is no where near my BulkCopyTimeout. Even though I get the exception that table is fully copied in the end. Also, if I truncate that table and restart my process for that table only, the tables is copied over without any issues. But going through the process of copying that entire database fails always for that one table. I have tried executing the entire process and reseting the connection before copying that faulty table, but it still errored out. My SqlBulkCopy and Reader are closed after each table. Any suggestions as to what else could be causing the script to fail at the point each time?

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• Does anyone have database, programming language/framework suggestions for a GUI point of sale system

  - by Jason Down

  Our company has a point of sale system with many extras, such as ordering and receiving functionality, sales and order history etc. Our main issue is that the system was not designed properly from the ground up, so it takes too long to make fixes and handle requests from our customers. Also, the current technology we are using (Progress database, Progress 4GL for the language) incurs quite a bit of licensing expenses on our customers due to mutli-user license fees for database connections etc. After a lot of discussion it is looking like we will probably start over from scratch (while maintaining the current product at least for the time being). We are looking for a couple of things: Create the system with a nice GUI front end (it is currently CHUI and the application was not built in a way that allows us to redesign the front end... no layering or separation of business logic and gui...shudder). Create the system with the ability to modularize different functionality so the product doesn't have to include all features. This would keep the cost down for our current customers that want basic functionality and a lower price tag. The bells and whistles would be available for those that would want them. Use proper design patterns to make the product easy to add or change any part at any time (i.e. change the database or change the front end without needing to rewrite the application or most of it). This is a problem today because the Progress 4GL code is directly compiled against the database. Small changes in the database requires lots of code recompiling. Our new system will be Linux based, with a possibility of a client application providing functionality from one or more windows boxes. So what I'm looking for is any suggestions on which database and/or framework or programming language(s) someone might recommend for this sort of product. Anyone that has experience in this field might be able to point us in the right direction or even have some ideas of what to avoid. We have considered .NET and SQL Express (we don't need an enterprise level DB), but that would limit us to windows (as far as I know anyway). I have heard of Mono for writing .NET code in a Linux environment, but I don't know much about it yet. We've also considered a Java and MySql based implementation. To summarize we are looking to do the following: Keep licensing costs down on the technology we will use to develop the product (Oracle, yikes! MySQL, nice.) Deliver a solution that is easily maintainable and supportable. A solution that has a component capable of running on "old" hardware through a CHUI front end. (some of our customers have 40+ terminals which would be a ton of cash in order to convert over to a PC). Suggestions would be appreciated. Thanks [UPDATE] I should note that we are currently performing a total cost analysis. This question is intended to give us a couple of "educated" options to look into to include in or analysis. Anyone who could share experiences/suggestions about client/server setups would be appreciated (not just those who have experience with point of sale systems... that would just be a bonus).

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• Appropriate programming design questions.

  - by Edward

  I have a few questions on good programming design. I'm going to first describe the project I'm building so you are better equipped to help me out. I am coding a Remote Assistance Tool similar to TeamViewer, Microsoft Remote Desktop, CrossLoop. It will incorporate concepts like UDP networking (using Lidgren networking library), NAT traversal (since many computers are invisible behind routers nowadays), Mirror Drivers (using DFMirage's Mirror Driver (http://www.demoforge.com/dfmirage.htm) for realtime screen grabbing on the remote computer). That being said, this program has a concept of being a client-server architecture, but I made only one program with both the functionality of client and server. That way, when the user runs my program, they can switch between giving assistance and receiving assistance without having to download a separate client or server module. I have a Windows Form that allows the user to choose between giving assistance and receiving assistance. I have another Windows Form for a file explorer module. I have another Windows Form for a chat module. I have another Windows Form form for a registry editor module. I have another Windows Form for the live control module. So I've got a Form for each module, which raises the first question: 1. Should I process module-specific commands inside the code of the respective Windows Form? Meaning, let's say I get a command with some data that enumerates the remote user's files for a specific directory. Obviously, I would have to update this on the File Explorer Windows Form and add the entries to the ListView. Should I be processing this code inside the Windows Form though? Or should I be handling this in another class (although I have to eventually pass the data to the Form to draw, of course). Or is it like a hybrid in which I process most of the data in another class and pass the final result to the Form to draw? So I've got like 5-6 forms, one for each module. The user starts up my program, enters the remote machine's ID (not IP, ID, because we are registering with an intermediary server to enable NAT traversal), their password, and connects. Now let's suppose the connection is successful. Then the user is presented with a form with all the different modules. So he can open up a File Explorer, or he can mess with the Registry Editor, or he can choose to Chat with his buddy. So now the program is sort of idle, just waiting for the user to do something. If the user opens up Live Control, then the program will be spending most of it's time receiving packets from the remote machine and drawing them to the form to provide a 'live' view. 2. Second design question. A spin off question #1. How would I pass module-specific commands to their respective Windows Forms? What I mean is, I have a class like "NetworkHandler.cs" that checks for messages from the remote machine. NetworkHandler.cs is a static class globally accessible. So let's say I get a command that enumerates the remote user's files for a specific directory. How would I "give" that command to the File Explorer Form. I was thinking of making an OnCommandReceivedEvent inside NetworkHandler, and having each form register to that event. When the NetworkHandler received a command, it would raise the event, all forms would check it to see if it was relevant, and the appropriate form would take action. Is this an appropriate/the best solution available? 3. The networking library I'm using, Lidgren, provides two options for checking networking messages. One can either poll ReadMessage() to return null or a message, or one can use an AutoResetEvent OnMessageReceived (I'm guessing this is like an event). Which one is more appropriate?

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• [C#][Design] Appropriate programming design questions.

  - by Edward

  I have a few questions on good programming design. I'm going to first describe the project I'm building so you are better equipped to help me out. I am coding a Remote Assistance Tool similar to TeamViewer, Microsoft Remote Desktop, CrossLoop. It will incorporate concepts like UDP networking (using Lidgren networking library), NAT traversal (since many computers are invisible behind routers nowadays), Mirror Drivers (using DFMirage's Mirror Driver (http://www.demoforge.com/dfmirage.htm) for realtime screen grabbing on the remote computer). That being said, this program has a concept of being a client-server architecture, but I made only one program with both the functionality of client and server. That way, when the user runs my program, they can switch between giving assistance and receiving assistance without having to download a separate client or server module. I have a Windows Form that allows the user to choose between giving assistance and receiving assistance. I have another Windows Form for a file explorer module. I have another Windows Form for a chat module. I have another Windows Form form for a registry editor module. I have another Windows Form for the live control module. So I've got a Form for each module, which raises the first question: 1. Should I process module-specific commands inside the code of the respective Windows Form? Meaning, let's say I get a command with some data that enumerates the remote user's files for a specific directory. Obviously, I would have to update this on the File Explorer Windows Form and add the entries to the ListView. Should I be processing this code inside the Windows Form though? Or should I be handling this in another class (although I have to eventually pass the data to the Form to draw, of course). Or is it like a hybrid in which I process most of the data in another class and pass the final result to the Form to draw? So I've got like 5-6 forms, one for each module. The user starts up my program, enters the remote machine's ID (not IP, ID, because we are registering with an intermediary server to enable NAT traversal), their password, and connects. Now let's suppose the connection is successful. Then the user is presented with a form with all the different modules. So he can open up a File Explorer, or he can mess with the Registry Editor, or he can choose to Chat with his buddy. So now the program is sort of idle, just waiting for the user to do something. If the user opens up Live Control, then the program will be spending most of it's time receiving packets from the remote machine and drawing them to the form to provide a 'live' view. 2. Second design question. A spin off question #1. How would I pass module-specific commands to their respective Windows Forms? What I mean is, I have a class like "NetworkHandler.cs" that checks for messages from the remote machine. NetworkHandler.cs is a static class globally accessible. So let's say I get a command that enumerates the remote user's files for a specific directory. How would I "give" that command to the File Explorer Form. I was thinking of making an OnCommandReceivedEvent inside NetworkHandler, and having each form register to that event. When the NetworkHandler received a command, it would raise the event, all forms would check it to see if it was relevant, and the appropriate form would take action. Is this an appropriate/the best solution available? 3. The networking library I'm using, Lidgren, provides two options for checking networking messages. One can either poll ReadMessage() to return null or a message, or one can use an AutoResetEvent OnMessageReceived (I'm guessing this is like an event). Which one is more appropriate?

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