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  • realtime visitors with nodejs & redis & socket.io & php

    - by orhan bengisu
    I am new to these tecnologies. I want to get realtime visitor for each products for my site. I mean a notify like "X users seeing this product". Whenever an user connects to a product counter will be increased for this product and when disconnects counter will be decreased just for this product. I tried to search a lots of documents but i got confused. I am using Predis Library for PHP. What i have done may totaly be wrong. I am not sure Where to put createClient , When to subscribe & When to unsubscribe. What I have done yet: On product detail page: $key = "product_views_".$product_id; $counter = $redis->incr($key); $redis->publish("productCounter", json_encode(array("product_id"=> "1000", "counter"=> $counter ))); In app.js var app = require('express')() , server = require('http').createServer(app) , socket = require('socket.io').listen(server,{ log: false }) , url = require('url') , http= require('http') , qs = require('querystring') ,redis = require("redis"); var connected_socket = 0; server.listen(8080); var productCounter = redis.createClient(); productCounter.subscribe("productCounter"); productCounter.on("message", function(channel, message){ console.log("%s, the message : %s", channel, message); io.sockets.emit(channel,message); } productCounter.on("unsubscribe", function(){ //I think to decrease counter here, Shold I? and How? } io.sockets.on('connection', function (socket) { connected_socket++; socket_id = socket.id; console.log("["+socket_id+"] connected"); socket.on('disconnect', function (socket) { connected_socket--; console.log("Client disconnected"); productCounter.unsubscribe("productCounter"); }); }) Thanks a lot for your answers!

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  • Administrators vs Programmers: Who's got more people Interaction / Working hours?

    - by sanksjaya
    Well, I've heard programmers get to interact with other programmers quiet a lot. But, who gets to meet a lot of new people on a daily basis at work without getting the feeling "Goosh! I'm stuck with him/this for another year :(" - Admins or Coders? And what kind of people domain do each get to interact with? Secondly, I've had this myth for a long time that unlike programmers, Network/System/Security Admins get locked-up in a den and juiced up late nights and early mornings. Most of the time they had to slip out of work without being noticed. But recently one of my seniors from my grad school told he had to work late and on weekends for a product release. How true and often does this happen with programmers and admins?

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  • Returning the same type the function was passed

    - by Ken Bloom
    I have the following code implementation of Breadth-First search. trait State{ def successors:Seq[State] def isSuccess:Boolean = false def admissableHeuristic:Double } def breadthFirstSearch(initial:State):Option[List[State]] = { val open= new scala.collection.mutable.Queue[List[State]] val closed = new scala.collection.mutable.HashSet[State] open.enqueue(initial::Nil) while (!open.isEmpty){ val path:List[State]=open.dequeue() if(path.head.isSuccess) return Some(path.reverse) closed += path.head for (x <- path.head.successors) if (!closed.contains(x)) open.enqueue(x::path) } return None } If I define a subtype of State for my particular problem class CannibalsState extends State { //... } What's the best way to make breadthFirstSearch return the same subtype as it was passed? Supposing I change this so that there are 3 different state classes for my particular problem and they share a common supertype: abstract class CannibalsState extends State { //... } class LeftSideOfRiver extends CannibalsState { //... } class InTransit extends CannibalsState { //... } class RightSideOfRiver extends CannibalsState { //... } How can I make the types work out so that breadthFirstSearch infers that the correct return type is CannibalsState when it's passed an instance of LeftSideOfRiver? Can this be done with an abstract type member, or must it be done with generics?

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  • How to manipulate *huge* amounts of data

    - by Alejandro
    Hi there! I'm having the following problem. I need to store huge amounts of information (~32 GB) and be able to manipulate it as fast as possible. I'm wondering what's the best way to do it (combinations of programming language + OS + whatever you think its important). The structure of the information I'm using is a 4D array (NxNxNxN) of double-precission floats (8 bytes). Right now my solution is to slice the 4D array into 2D arrays and store them in separate files in the HDD of my computer. This is really slow and the manipulation of the data is unbearable, so this is no solution at all! I'm thinking on moving into a Supercomputing facility in my country and store all the information in the RAM, but I'm not sure how to implement an application to take advantage of it (I'm not a professional programmer, so any book/reference will help me a lot). An alternative solution I'm thinking on is to buy a dedicated server with lots of RAM, but I don't know for sure if that will solve the problem. So right now my ignorance doesn't let me choose the best way to proceed. What would you do if you were in this situation? I'm open to any idea. Thanks in advance!

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  • Finding Cities within 'X' Kilometers (or Miles)

    - by Mike Curry
    This may or may not be clear, leave me a comment if I am off base, or you need more information. Perhaps there is a solution out there already for what I want in PHP. I am looking for a function that will add or subtract a distance from a longitude OR latitude value. Reason: I have a database with all Latitudes and Longitudes in it and want to form a query to extract all cities within X kilometers (or miles). My query would look something like this... Select * From Cities Where (Longitude > X1 and Longitude < X2) And (Latitude > Y1 and Latitude < Y2) Where X1 = Longitude - (distance) Where X2 = Longitude + (distance) Where Y1 = Latitude - (distance) Where Y2 = Latitude + (distance) I am working in PHP, with a MySql Database. Open to any suggestions also! :)

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  • Get coordinates in parent, but not in stage.

    - by Bart van Heukelom
    I know about Flash's localToGlobal and globalToLocal methods to transform coordinates from the local system to the global system, but is there a way to achieve the intermediate? To transform coordinates from an arbitrary system to any other arbitrary system? I have a clickable object inside a Sprite, and the Sprite is a child of the stage. I want to retrieve the clicked point in the Sprite.

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  • Which parts of Graphics Pipelines are done using CPU & GPU?

    - by afriza
    Which parts of pipelines are done using CPU and which are done using GPU? Reading Wikipedia on Graphics Pipeline, maybe my question does not precisely represent what I am asking. Referring to this question, which "steps" are done in CPU and which are done in GPU? Edit: My question is more into which parts of logical high level steps needed to display terrain+3D models are using CPU/GPU instead of which functions.

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  • Are there any languages that are dynamically typed but do not allow weak typing?

    - by Maulrus
    For example, adding a (previously undeclared) int and a string in pseudocode: x = 1; y = "2"; x + y = z; I've seen strongly typed languages that would not allow adding the two types, but those are also statically typed, so it's impossible to have a situation like above. On the other hand, I've seen weakly typed languages that allow the above and are statically typed. Are there any languages that are dynamically typed but are also strongly typed as well, so that the piece of code above would not be valid?

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  • open source gossip-based membership protocol?

    - by Aaron
    I am looking for a library which I can plug into a distributed application which implements any gossip-based membership protocol. Such a library would allow me to send/receive membership lists, merge received membership lists, etc... Even better would be if the library implemented a protocol with performance O(logn) performance guarantees. Does anyone know of any open source library like this? It doesn't need to meet all of the aforementioned requirements; even something partially implemented would be helpful.

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  • Decoding mysql_real_escape_string() for outputting HTML

    - by Peter
    I'm trying to protect myself from sql injection and am using: mysql_real_escape_string($string); When posting HTML it looks something like this: <span class="\&quot;className\&quot;"> <p class="\&quot;pClass\&quot;" id="\&quot;pId\&quot;"></p> </span> I'm not sure how many other variations real_escape_string adds so don't want to just replace a few and miss others... How do I "decode" this back into correctly formatted HTML, with something like: html_entity_decode(stripslashes($string));

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  • Ajax Push Engine

    - by gkrdvl
    Hi all, are there anyone hear about APE (Ajax Push Engine) before ? I'm building Rails application and trying to create group chat with this APE realtime engine, the problem is how to make Rails communicate with APE Server ? Are there any tutorial or reference on working APE with Rails ?

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  • Opengl Coordinate System

    - by praveen
    Say I am using an Identity Matrix for my modelViewTransformation Matrix on an Open GL ES2.0 program. The Co-ordinate system in this case is the canonical opengl co-ordinate system which extends from (-1,-1,-1) to (1,,1,1). My question is, is this coordinate system right-handed or left-handed? A broader question: Is there a document with OpenGL which can list all the mathematical conventions followed by the API?

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  • mysqli real_escape_string problem

    - by tridat
    When im inserting to the database on my dev server the text goes in fine, for example "that's" is "that's" in the db. when uploading the exact same code to production server (hosted on a reseller account at bluehost) "that's" becomes "that\'s", im not double escaping, its exactly the same code, what could be the issue here?

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  • Algorithm for non-contiguous netmask match

    - by Gianluca
    Hi, I have to write a really really fast algorithm to match an IP address to a list of groups, where each group is defined using a notation like 192.168.0.0/252.255.0.255. As you can see, the bitmask can contain zeros even in the middle, so the traditional "longest prefix match" algorithms won't work. If an IP matches two groups, it will be assigned to the group containing most 1's in the netmask. I'm not working with many entries (let's say < 1000) and I don't want to use a data structure requiring a large memory footprint (let's say 1-2 MB), but it really has to be fast (of course I can't afford a linear search). Do you have any suggestion? Thanks guys. UPDATE: I found something quite interesting at http://www.cse.usf.edu/~ligatti/papers/grouper-conf.pdf, but it's still too memory-hungry for my utopic use case

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  • What's the "Hello World!" of genetic algorithms good for?

    - by JohnIdol
    I found this very cool C++ sample , literally the "Hello World!" of genetic algorithms. I so decided to re-code the whole thing in C# and this is the result. Now I am asking myself: is there any practical application along the lines of generating a target string starting from a population of random strings? EDIT: my buddy on twitter just tweeted that "is useful for transcription type things such as translation. Does not have to be Monkey's". I wish I had a clue.

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  • Calculate total time between Dates in Hours and Minutes

    - by matthew parkes
    Hi I’m trying to resolve a problem using VB and I need some assistance. I’m very new to the language (1 week). The problem is I have created a user form to show how many hours and minutes has elapsed between two different times similar to a time sheet. The user form consists of two calendars, and under each calendar there are two text boxes; one box each to record the Hour and Minute they left and two further boxes to record the time they arrived back. I have used the code to minus the calendars together (e.g calendar in – calendar out) then times this by 24 to indicate the hours away. Then under the calendar out I have a text box for the user to type in the hour they left. Then I minus the 24 by the Hour out e.g. if it was 24 -15 it will appear 9 ( 9 hours of that day ) then I would add that to the figure they inserted in the text box Hour in (Return Time). e.g 14. Then I would add them to together e.g. 9 + 14 = 23 and have this displayed in another text box Total Hours. Therefore it would display 23 meaning 23 hours. I have then want to show another two text boxes to indicate minutes. One for Minutes Out then Minutes In. I have the problem to convert these minutes for instance if it is the out time is 15:50 and the in time the next day is at 15:55 it displays as 24 (in one text box) and 105 minutes (in the other text box). I would like the minutes added to the hour and have the balance of the remaining minutes in the minute text box. This should display 24 (in one text box) and 5 (in another text box). The ultimate aim is to get a result that shows a person was absent for a number of days, hours and minutes, eg, 2 days, 5 hours and 10 minutes. Any ideas on how I can modify my code to achieve this? Here’s my code. Please Help Dim number1 As Date Dim number2 As Date Dim number3 As Integer Dim number4 As Integer Dim Number5 As Integer Dim Number6 As Integer Dim answer As Integer Dim answer2 As Integer Dim answer3 As Integer Dim answer4 As Integer Dim answer5 As String number1 = DTPicker1 number2 = DTPicker2 number3 = Txthourout number4 = TxtHourin Number5 = TxtMinuteout Number6 = TxtMinuetIn answer = number2 - number1 answer2 = answer * 24 answer3 = answer2 - number3 answer4 = answer3 + number4 answer5 = Number5 + Number6 TextBox1.Text = answer4 TextBox2.Text = answer5 End Sub

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  • Ubuntu Linux main utilities

    - by Harry
    I've never used Ubuntu Linux before, but I am researching about the main system tools that are included, e.g. Windows has Disk Cleanup, Disk Defrag... but what does Ubuntu Linux have. I need to know what the main five utilities that are included on Ubuntu Linux and what do they do.

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