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  • Weird Network Behavior of Home Router

    - by Stilgar
    First of all I would like to apologize because what you are going to read will be long and confusing but I am fighting this issue for 3 days now and am out of ideas. At home I have the following setup 50Mbps Internet connects into a home router A 2 desktop computers connect to router A via standard FTP LAN cables including one where the cable is ~20m long. a second router B connects to router A via standard FTP LAN cable X (~20m long). several devices connect to the wireless network of router B and there are a couple of desktop computers connected to it through FTP LAN cables. For some reason computers connected to router B when it is connected via cable X have very slow Internet connection. It is like 5 times slower than what is expected. This is the actual problem I am trying to solve. Interesting facts If a computer is connected to cable X directly instead of through router B the Internet speed is just fine (up to the 50Mbps I get from the ISP). Tested with two computers. I have tried replacing router B with another router C and the problem persists. If I connect router B via another cable to the same ports with the same settings everything seems to work fine and computers connected to router B have quite fast Internet I have tested mainly via Speedtest.net but I have also achieved similar speeds when downloading a file The upload speed is quite higher than the download speed in all cases. Note that my ISP usually has higher upload speed (unless it manages to hit the 50Mbps cap) It seems like the speed when connecting through router B with cable X is reduced 4-5 times no matter what the original speed is. For example via router B I get 10Mbps speed to local servers where I get 50Mbps when connected on router A. If I use a distant server where the ISP is only able to provide 25Mbps I get 4-5Mbps on router B. WiFi is slower than LAN on both routers (which is normal) but the reduced speed is reduced proportionally for WiFi. In addition the upload speed is normally higher from the ISP and it is also reduced proportionally. I have tried two different network configurations. One where I have NAT behind NAT where router B connects to router A via the WAN port and has its own DHCP. Second where router B connects to router A via standard LAN port and has DHCP disabled. In this configuration router B serves as a switch and the Network Gateway for computers connected to router B is the internal IP address of router A. Both configurations work just fine but both manifest the reduced speed issue. pings seem to work just fine As far as I can tell none of the cables is crossed The RJ45 setup for cable X orange orange-white brown brow-white blue blue-white green green-white This is a big problem for me since cable X passes through walls and floors and is very hard to replace. I also may have gotten some of the facts wrong because I am almost going crazy with this issue and testing includes going several floors up and down the staircase. One hypothesis I came up with is that the cable is defective in such a way that the voltage from the router affects its performance. When it is connected to a computer it performs just fine but the router has less power. Related hypothesis includes the cable being affected by electricity cables in the walls when the voltage is low. (I know nothing about electricity) So any ideas what to do, what to test or what the issue may be?

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  • Does this prove a network bandwidth bottleneck?

    - by Yuji Tomita
    I've incorrectly assumed that my internal AB testing means my server can handle 1k concurrency @3k hits per second. My theory at at the moment is that the network is the bottleneck. The server can't send enough data fast enough. External testing from blitz.io at 1k concurrency shows my hits/s capping off at 180, with pages taking longer and longer to respond as the server is only able to return 180 per second. I've served a blank file from nginx and benched it: it scales 1:1 with concurrency. Now to rule out IO / memcached bottlenecks (nginx normally pulls from memcached), I serve up a static version of the cached page from the filesystem. The results are very similar to my original test; I'm capped at around 180 RPS. Splitting the HTML page in half gives me double the RPS, so it's definitely limited by the size of the page. If I internally ApacheBench from the local server, I get consistent results of around 4k RPS on both the Full Page and the Half Page, at high transfer rates. Transfer rate: 62586.14 [Kbytes/sec] received If I AB from an external server, I get around 180RPS - same as the blitz.io results. How do I know it's not intentional throttling? If I benchmark from multiple external servers, all results become poor which leads me to believe the problem is in MY servers outbound traffic, not a download speed issue with my benchmarking servers / blitz.io. So I'm back to my conclusion that my server can't send data fast enough. Am I right? Are there other ways to interpret this data? Is the solution/optimization to set up multiple servers + load balancing that can each serve 180 hits per second? I'm quite new to server optimization, so I'd appreciate any confirmation interpreting this data. Outbound traffic Here's more information about the outbound bandwidth: The network graph shows a maximum output of 16 Mb/s: 16 megabits per second. Doesn't sound like much at all. Due to a suggestion about throttling, I looked into this and found that linode has a 50mbps cap (which I'm not even close to hitting, apparently). I had it raised to 100mbps. Since linode caps my traffic, and I'm not even hitting it, does this mean that my server should indeed be capable of outputting up to 100mbps but is limited by some other internal bottleneck? I just don't understand how networks at this large of a scale work; can they literally send data as fast as they can read from the HDD? Is the network pipe that big? In conclusion 1: Based on the above, I'm thinking I can definitely raise my 180RPS by adding an nginx load balancer on top of a multi nginx server setup at exactly 180RPS per server behind the LB. 2: If linode has a 50/100mbit limit that I'm not hitting at all, there must be something I can do to hit that limit with my single server setup. If I can read / transmit data fast enough locally, and linode even bothers to have a 50mbit/100mbit cap, there must be an internal bottleneck that's not allowing me to hit those caps that I'm not sure how to detect. Correct? I realize the question is huge and vague now, but I'm not sure how to condense it. Any input is appreciated on any conclusion I've made.

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  • Arduino - AdHoc Network Setup

    - by methodMan
    I`m currently working with an arduino trying to build an adhoc network to which a device can connect to and send web request to. The problem I am currently having is that I can only set up one connection and then when that connection is terminated (client.stop()) all subsequent connections are not picked up by the server, even a curl command just sits there spinning. The first connection I start when I reset the server works fine and I am able to talk to the server; but after that, the arduino can no longer find new clients (even though it's trying with the library given). I`m using the sparkfun library for the wifly shield cloned from github, along with an Arduino Uno. My current code is based off their default example 'WiFly_AdHoc_Example' but I had to remove a few things to get the network to start up which might be the cause of this problem. Here is the .ino file that I am running. #include <SPI.h> #include <WiFly.h> //#include <SoftwareSerial.h> //SoftwareSerial mySerial( 5, 4); //Part from example not used(see below) WiFlyServer server(80); void setup() { Serial.begin(9600); //The code below is from the example but when I run it the WiFly will hang // on Wifly.begin(). Without it the WiFly starts up fine but only works for // one request. //mySerial.begin(9600); //WiFly.setUart(&mySerial); // Tell the WiFly library that we are not //using the SPIUart Serial.println("**************Starting WiFly**************"); // Enable Adhoc mod WiFly.begin(true); Serial.println("WiFly started, creating network."); if (!WiFly.createAdHocNetwork("wifly")) { Serial.print("Failed to create ad hoc network."); while (1) { // Hang on failure. } } Serial.println("Network created"); Serial.print("IP: "); Serial.println(WiFly.ip()); Serial.println("Starting Server..."); server.begin(); Serial.print("Server started, waiting for client."); } void loop() { delay(200); WiFlyClient client = server.available(); if (client) { Serial.println("Client Found."); // a string to store received commands String current_command = ""; while (client.connected()) { if (client.available()) { //Gets a character from the sent request. char c = client.read(); if (c=='#' || c=='\n') //End of extraneous output { current_command = ""; } else if(c!= '\n') { current_command+=c; } if (current_command== "get") { // output the value of each analog input pin for (int i = 0; i < 6; i++) { client.print("analog input "); client.print(i); client.print(" is "); client.print(analogRead(i)); client.println("<br />"); } } else if(current_command== "hello") { client.println("Hello there, I'm still here."); } else if (current_command== "quit") { client.println("Goodbye..."); client.stop(); current_command == ""; break; } else if (current_command == "*OPEN*") { current_command == ""; } } } // give the web browser time to receive the data delay(200); // close the connection client.stop(); } } If anyone understands this better then I (I`m new to arduino) please leave some helpful comments. Or just help me out on getting this little web server up and running so that I can hit it with more then one request. If there is any other helpful information I can provide please let me know. Thanks for reading and hope you can help. EDIT: Using telnet I can successfully connect (the first time) and send commands to the arduino including one to terminate the connection (calls the client.stop() method). But when I try to reconnect though telnet, it says the connection was successful but on the arduino it's still looping thinking the client is still false. WHAT??? I know right, I'm getting mixed messages from telnet vs arduino. None of the commands work obviously since the ardunio is still looping waiting for a client that evaluates to true. I'm gonna take a look at WiFlyServer from the library I imported and see if I can dig up the problem because somehow that server.available() method isn't finding new clients. Noticing a lot of TODO's in the library code.... EDIT: So I found the reason for the problem, it was in WiFlyServer.cpp file from the sparkfun library. The code that was causing the reconnect issue was infact in the server.availible() method. Right at the top of the method, there is a check: // TODO: Ensure no active non-server client connection. if (!WiFly.serverConnectionActive) { activeClient._port = 0; } For some reason when I comment this out, I can reconnect fine and everything works as it should. I will now dive into the library and see if I can fix this, I'm not exactly sure what this is doing but it gets called when the server connection is not active and is somehow blocking subsequent connections. Does anyone have any ideas how I might get to the root of this problem without using this commenting hack? Please help, no-one has commented or answered yet! Don't you want to join in on the fun???

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  • What to filter when providing very limited open WiFi to a small conference or meeting?

    - by Tim Farley
    Executive Summary The basic question is: if you have a very limited bandwidth WiFi to provide Internet for a small meeting of only a day or two, how do you set the filters on the router to avoid one or two users monopolizing all the available bandwidth? For folks who don't have the time to read the details below, I am NOT looking for any of these answers: Secure the router and only let a few trusted people use it Tell everyone to turn off unused services & generally police themselves Monitor the traffic with a sniffer and add filters as needed I am aware of all of that. None are appropriate for reasons that will become clear. ALSO NOTE: There is already a question concerning providing adequate WiFi at large (500 attendees) conferences here. This question concerns SMALL meetings of less than 200 people, typically with less than half that using the WiFi. Something that can be handled with a single home or small office router. Background I've used a 3G/4G router device to provide WiFi to small meetings in the past with some success. By small I mean single-room conferences or meetings on the order of a barcamp or Skepticamp or user group meeting. These meetings sometimes have technical attendees there, but not exclusively. Usually less than half to a third of the attendees will actually use the WiFi. Maximum meeting size I'm talking about is 100 to 200 people. I typically use a Cradlepoint MBR-1000 but many other devices exist, especially all-in-one units supplied by 3G and/or 4G vendors like Verizon, Sprint and Clear. These devices take a 3G or 4G internet connection and fan it out to multiple users using WiFi. One key aspect of providing net access this way is the limited bandwidth available over 3G/4G. Even with something like the Cradlepoint which can load-balance multiple radios, you are only going to achieve a few megabits of download speed and maybe a megabit or so of upload speed. That's a best case scenario. Often it is considerably slower. The goal in most of these meeting situations is to allow folks access to services like email, web, social media, chat services and so on. This is so they can live-blog or live-tweet the proceedings, or simply chat online or otherwise stay in touch (with both attendees and non-attendees) while the meeting proceeds. I would like to limit the services provided by the router to just those services that meet those needs. Problems In particular I have noticed a couple of scenarios where particular users end up abusing most of the bandwidth on the router, to the detriment of everyone. These boil into two areas: Intentional use. Folks looking at YouTube videos, downloading podcasts to their iPod, and otherwise using the bandwidth for things that really aren't appropriate in a meeting room where you should be paying attention to the speaker and/or interacting.At one meeting that we were live-streaming (over a separate, dedicated connection) via UStream, I noticed several folks in the room that had the UStream page up so they could interact with the meeting chat - apparently oblivious that they were wasting bandwidth streaming back video of something that was taking place right in front of them. Unintentional use. There are a variety of software utilities that will make extensive use of bandwidth in the background, that folks often have installed on their laptops and smartphones, perhaps without realizing.Examples: Peer to peer downloading programs such as Bittorrent that run in the background Automatic software update services. These are legion, as every major software vendor has their own, so one can easily have Microsoft, Apple, Mozilla, Adobe, Google and others all trying to download updates in the background. Security software that downloads new signatures such as anti-virus, anti-malware, etc. Backup software and other software that "syncs" in the background to cloud services. For some numbers on how much network bandwidth gets sucked up by these non-web, non-email type services, check out this recent Wired article. Apparently web, email and chat all together are less than one quarter of the Internet traffic now. If the numbers in that article are correct, by filtering out all the other stuff I should be able to increase the usefulness of the WiFi four-fold. Now, in some situations I've been able to control access using security on the router to limit it to a very small group of people (typically the organizers of the meeting). But that's not always appropriate. At an upcoming meeting I would like to run the WiFi without security and let anyone use it, because it happens at the meeting location the 4G coverage in my town is particularly excellent. In a recent test I got 10 Megabits down at the meeting site. The "tell people to police themselves" solution mentioned at top is not appropriate because of (a) a largely non-technical audience and (b) the unintentional nature of much of the usage as described above. The "run a sniffer and filter as needed" solution is not useful because these meetings typically only last a couple of days, often only one day, and have a very small volunteer staff. I don't have a person to dedicate to network monitoring, and by the time we got the rules tweaked completely the meeting will be over. What I've Got First thing, I figured I would use OpenDNS's domain filtering rules to filter out whole classes of sites. A number of video and peer-to-peer sites can be wiped out using this. (Yes, I am aware that filtering via DNS technically leaves the services accessible - remember, these are largely non-technical users attending a 2 day meeting. It's enough). I figured I would start with these selections in OpenDNS's UI: I figure I will probably also block DNS (port 53) to anything other than the router itself, so that folks can't bypass my DNS configuration. A savvy user could get around this, because I'm not going to put a lot of elaborate filters on the firewall, but I don't care too much. Because these meetings don't last very long, its probably not going to be worth the trouble. This should cover the bulk of the non-web traffic, i.e. peer-to-peer and video if that Wired article is correct. Please advise if you think there are severe limitations to the OpenDNS approach. What I Need Note that OpenDNS focuses on things that are "objectionable" in some context or another. Video, music, radio and peer-to-peer all get covered. I still need to cover a number of perfectly reasonable things that we just want to block because they aren't needed in a meeting. Most of these are utilities that upload or download legit things in the background. Specifically, I'd like to know port numbers or DNS names to filter in order to effectively disable the following services: Microsoft automatic updates Apple automatic updates Adobe automatic updates Google automatic updates Other major software update services Major virus/malware/security signature updates Major background backup services Other services that run in the background and can eat lots of bandwidth I also would like any other suggestions you might have that would be applicable. Sorry to be so verbose, but I find it helps to be very, very clear on questions of this nature, and I already have half a solution with the OpenDNS thing.

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  • Using FFmpeg in c#?

    - by daniel
    So i know its a fairly big challenge but i want to write a basic movie player/converter in c# using the FFmpeg library. However the first obstacle i need to overcome is wrapping the FFmpeg library in c#. I downloaded ffmpeg but couldn't compile it on windows, so i downloaded a precompiled version for me. Ok awesome. Then i started looking for c# wrappers. I have looked around and have found a few wrappers such as SharpFFmpeg (http://sourceforge.net/projects/sharpffmpeg/) and ffmpeg-sharp (http://code.google.com/p/ffmpeg-sharp/). First of all i wanted to use ffmpeg-sharp as its LGPL and SharpFFmpeg is GPL. However it had quite a few compile errors. Turns out it was written for the mono compiler, i tried compiling it with mon but couldn't figure out how. I then started to manually fix the compiler errors myself, but came across a few scary ones and thought i'd better leave those alone. So i gave up on ffmpeg-sharp. Then i looked at SharpFFmpeg and it looks like what i want, all the functions P/Invoked for me. However its GPL? Both the AVCodec.cs and AVFormat.cs files look like ports of avcodec.c and avformat.c which i reckon i could port myself? Then not have to worry about licencing. But i wan't to get this right before i go ahead and start coding. Should I: Write my own c++ library for interacting with ffmpeg, then have my c# program talk to the c++ library in order to play/convert videos etc. OR Port avcodec.h and avformat.h (is that all i need?) to c# by using a whole lot of DllImports and write it entirely in c#? First of all consider that i'm not great at c++ as i rarely use it but i know enough to get around. The reason i'm thinking #1 might be the better option is that most FFmpeg tutorials are in c++ and i'd also have more control over memory management that if i was to do it in c#. What do you think? Also would you happen to have any usefull links (perhaps a tutorial) for using FFmpeg? EDIT: spelling mistakes

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  • Using FFmpeg in .net?

    - by daniel
    So i know its a fairly big challenge but i want to write a basic movie player/converter in c# using the FFmpeg library. However the first obstacle i need to overcome is wrapping the FFmpeg library in c#. I downloaded ffmpeg but couldn't compile it on windows, so i downloaded a precompiled version for me. Ok awesome. Then i started looking for c# wrappers. I have looked around and have found a few wrappers such as SharpFFmpeg (http://sourceforge.net/projects/sharpffmpeg/) and ffmpeg-sharp (http://code.google.com/p/ffmpeg-sharp/). First of all i wanted to use ffmpeg-sharp as its LGPL and SharpFFmpeg is GPL. However it had quite a few compile errors. Turns out it was written for the mono compiler, i tried compiling it with mon but couldn't figure out how. I then started to manually fix the compiler errors myself, but came across a few scary ones and thought i'd better leave those alone. So i gave up on ffmpeg-sharp. Then i looked at SharpFFmpeg and it looks like what i want, all the functions P/Invoked for me. However its GPL? Both the AVCodec.cs and AVFormat.cs files look like ports of avcodec.c and avformat.c which i reckon i could port myself? Then not have to worry about licencing. But i wan't to get this right before i go ahead and start coding. Should I: Write my own c++ library for interacting with ffmpeg, then have my c# program talk to the c++ library in order to play/convert videos etc. OR Port avcodec.h and avformat.h (is that all i need?) to c# by using a whole lot of DllImports and write it entirely in c#? First of all consider that i'm not great at c++ as i rarely use it but i know enough to get around. The reason i'm thinking #1 might be the better option is that most FFmpeg tutorials are in c++ and i'd also have more control over memory management than if i was to do it in c#. What do you think? Also would you happen to have any usefull links (perhaps a tutorial) for using FFmpeg? EDIT: spelling mistakes

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  • Good C# Networking Book

    - by Dan
    Hey guys I am looking for a good solid introduction book to the fundementals of network programming in C#. For example is have looked at this one http://www.amazon.com/C-Network-Programming-Richard-Blum/dp/0782141765/ref=pd_sim_b_5 but it is quite old now. Anyone used one recently, i would greatly appriciate it thanks dan

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  • dns_sd.h not found in windows

    - by sneha
    Hello everyone,I am doing a qt application for bonjour advertising..so i need to use dns_sd library for that.can anyone let me know where i can find that library or ddl or dns_sd.h file..when i compile my program i get an error "dns_sd.h no such file"(I am working under windows)

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  • Per Application Packet Analyzer

    - by Anindya Chatterjee
    Is there any tool which can analyze network traffic per application? Wireshark does not have per application filtering, fiddler also does not give proper logging for any application. So can anyone please help me out to find an app which can analyze network traffic originating from a random application and log the traffic for that particular application only?

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  • What is the iPhone simulator IP address?

    - by Chris G
    Hi I have been looking for the answer to this question for some time. I am doing network programming for the iPhone and it is necessary for me to use the IP address of the device. This isn't a problem on the physical device as it has its own IP address on the network. However I was wondering what was the case with it on the simulator. Does it get assigned an IP address to be used? Thanks in advanced for any help, CG

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  • Account sharing among Ubuntu machines

    - by muckabout
    I'd like a simple and secure system to have allow users in our network to have their account (e.g., 'myname') work on every machine in the network (e.g., such that they could ssh to any machine and have the same userid, mounted smb share). Any suggestions?

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  • C# - NetworkChangeEventHandler

    - by Andy
    I have small application which catches Network Availability change and its working very fine in client Desktop m/c (which is having XP) But when I tested the same in Vista by disabling the network and enabling it again..the event is not getting triggered. NetworkChange.NetworkAvailabilityChanged += new NetworkAvailabilityChangedEventHandler(NetworkChange_NetworkAvailabilityChanged); private void NetworkChange_NetworkAvailabilityChanged(object sender, NetworkAvailabilityEventArgs e) {.....} Does .Net framework 3.5 got any new solution introduced ...

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  • AESlibrary only two lines

    - by user303968
    Does anyone know a c++ library that uses advanced encryption standard encryption that can achieve encryption and decryption (using counter mode) in just two lines of codes. No need of padding or buffering the plaintexts the library will take care of all this. I have had a look at crypto++, openssl and libtomcrypt but in these it seems I need to write codes to buffer and pad the plaintexts which I don't want. In brief, I need something along these lines: ciphertext = encrypt(ctr_mode(),plaintext,key) plaintext = decrypt(ctr_mode(),ciphertext,key) Thanks!

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  • Best open source C# libaries?

    - by Alon
    There are great .NET libraries and components. What is, for your opinion the most useful, effective, well wrriten open source C# library you've ever seen? Mines, is the great Html Agility Pack. Please post one library per answer.

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  • Loading c libraries from php

    - by Thomas Ahle
    Hi, in a recent project I've come really need the lib tre matching library. However the project is in php, and there are no php bindings for the library. I've tried to google how to create an interface for c libs, but all I found was the dl function which seams to load only php extensions. What am I missing?

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  • Compatibility between Qt and Boost sockets libraries

    - by cake
    Hello In my work, I'm developing a Viewer client for a Offshore simulation server, using sockets to send the simulation data from the Simulator to de Viewer. But, the server uses Boost.asio as it's sockets library. As the client uses Qt for it's GUI, I was wondering if there is any problem in using de Qt Networking library for handling the sockets. Is there any compatibility issues? Thanks in advance, and sorry for my bad english.

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  • Java GUI libraries

    - by Dan
    I have been working with the Swing library for a long time, I'm working on a new project for school and due to the nature of the program it can't look like a generic/boring swing gui. So my question is does anyone know of an interesting java gui library that is not swing or awt?

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  • Activation Function, Initializer function, etc, effects on neural networks for face detection

    - by harry
    There's various activation functions: sigmoid, tanh, etc. And there's also a few initializer functions: Nguyen and Widrow, random, normalized, constant, zero, etc. So do these have much effect on the outcome of a neural network specialising in face detection? Right now I'm using the Tanh activation function and just randomising all the weights from -0.5 to 0.5. I have no idea if this is the best approach though, and with 4 hours to train the network each time, I'd rather ask on here than experiment!

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  • copy files to nework path or Drive using python

    - by user218976
    hi , Mine is similar to this question. http://stackoverflow.com/questions/2042342/network-path-and-variables-in-python/2042376 The only difference is my network drive has a password protect with user name and password . I need to copy files to a samba share using python and verify it. if i manually login in then the code works but without logging in the shutil command does not work Thanks

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  • Data structures libaray in C

    - by Vineel Kumar Reddy
    Hi all I am very much used to .NET and java collection libraries and searching for a similar library in C. I am in need of following A list data structure for storing generic objects. and also a Dictionary data structure for key value pairs. Please let me know if any library exists. Thanks.

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