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  • Tiled game: how to correct load background image ?

    - by stighy
    Hi, i'm a newbie. I'm trying to develop a 2d game (top-down view). I would like to load a standard background, a textured ground... My "world" is big, for example 3000px X 3000px. I think it is not a good idea to load a 3000px x 3000px image and move it... So, how is the best practice ? To load a single small image (64x64) and repeat it for N times ? If yes, ok, but how i can manage the "background" movement ? Thanks Bye!

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  • Can web apps allow fast data-typists to "type-ahead"?

    - by user61852
    In some data entry contexts, I've seen data typists, type really fast and know so well the app they use, and have a mechanic quality in their work so that they can "type ahead", ie continue typing and "tab-bing" and "enter-ing" faster than the display updates, so that in many occasions they are typing in the data for the next form before it draws itself. Then when this next entry form appears, their keystrokes fill the text boxes and they continue typing, selecting etc. In contexts like this, this speed is desirable, since this persons are really productive. I think this "type ahead of time" is only possible in desktop apps, but I may be wrong. My question is whether this way of handling the keyboard buffer (which in desktop apps require no extra programming) is achievable in web apps, or is this impossible because of the way web apps work, handle sessions, etc (network latency and the overhead of generating new web pages ) ? Edit: By "type ahead" I mean "keyboard type ahead" (typing faster than the next entry form can load), not suggets-as-you-type-like-google type ahead. Typeahead is a feature of computers and software (and some typewriters) that enables users to continue typing regardless of program or computer operation—the user may type in whatever speed he or she desires, and if the receiving software is busy at the time it will be called to handle this later. Often this means that keystrokes entered will not be displayed on the screen immediately. This programming technique for handling user what is known as a keyboard buffer.

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  • Can't load some domain

    - by Grzegorz
    I can't load some domain on my ubuntu 13.04: youtube.com translate.google.com drive.google.com vk.com When I ping them they are responding: PING youtube.com (217.119.79.59) 56(84) bytes of data. 64 bytes from non-registered.plix.pl (217.119.79.59): icmp_req=1 ttl=59 time=21.9 ms 64 bytes from non-registered.plix.pl (217.119.79.59): icmp_req=2 ttl=59 time=20.5 ms 64 bytes from non-registered.plix.pl (217.119.79.59): icmp_req=3 ttl=59 time=21.3 ms --- youtube.com ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2002ms rtt min/avg/max/mdev = 20.544/21.255/21.914/0.560 ms But they don't load in any browser like firefox, chrome, lynx. They load in my media centre on XBMCbuntu.

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  • jqGrid - dynamically load different drop down values for different rows depending on another column value

    - by Renso
    Goal: As we all know the jqGrid examples in the demo and the Wiki always refer to static values for drop down boxes. This of course is a personal preference but in dynamic design these values should be populated from the database/xml file, etc, ideally JSON formatted. Can you do this in jqGrid, yes, but with some custom coding which we will briefly show below (refer to some of my other blog entries for a more detailed discussion on this topic). What you CANNOT do in jqGrid, referrign here up and to version 3.8.x, is to load different drop down values for different rows in the jqGrid. Well, not without some trickery, which is what this discussion is about. Issue: Of course the issue is that jqGrid has been designed for high performance and thus I have no issue with them loading a  reference to a single drop down values list for every column. This way if you have 500 rows or one, each row only refers to a single list for that particuolar column. Nice! SO how easy would it be to simply traverse the grid once loaded on gridComplete or loadComplete and simply load the select tag's options from scratch, via ajax, from memory variable, hard coded etc? Impossible! Since their is no embedded SELECT tag within each cell containing the drop down values (remeber it only has a reference to that list in memory), all you will see when you inspect the cell prior to clicking on it, or even before and on beforeEditCell, is an empty <TD></TD>. When trying to load that list via a click event on that cell will temporarily load the list but jqGrid's last internal callback event will remove it and replace it with the old one, and you are back to square one. Solution: Yes, after spending a few hours on this found a solution to the problem that does not require any updates to jqGrid source code, thank GOD! Before we get into the coding details, the solution here can of course be customized to suite your specific needs, this one loads the entire drop down list that would be needed across all rows once into global variable. I then parse this object that contains all the properties I need to filter the rows depending on which ones I want the user to see based off of another cell value in that row. This only happens when clicking the cell, so no performance penalty. You may of course to load it via ajax when the user clicks the cell, but I found it more effecient to load the entire list as part of jqGrid's normal editoptions: { multiple: false, value: listingStatus } colModel options which again keeps only a reference to the sinlge list, no duplciation. Lets get into the meat and potatoes of it.         var acctId = $('#Id').val();         var data = $.ajax({ url: $('#ajaxGetAllMaterialsTrackingLookupDataUrl').val(), data: { accountId: acctId }, dataType: 'json', async: false, success: function(data, result) { if (!result) alert('Failure to retrieve the Alert related lookup data.'); } }).responseText;         var lookupData = eval('(' + data + ')');         var listingCategory = lookupData.ListingCategory;         var listingStatus = lookupData.ListingStatus;         var catList = '{';         $(lookupData.ListingCategory).each(function() {             catList += this.Id + ':"' + this.Name + '",';         });         catList += '}';         var lastsel;         var ignoreAlert = true;         $(item)         .jqGrid({             url: listURL,             postData: '',             datatype: "local",             colNames: ['Id', 'Name', 'Commission<br />Rep', 'Business<br />Group', 'Order<br />Date', 'Edit', 'TBD', 'Month', 'Year', 'Week', 'Product', 'Product<br />Type', 'Online/<br />Magazine', 'Materials', 'Special<br />Placement', 'Logo', 'Image', 'Text', 'Contact<br />Info', 'Everthing<br />In', 'Category', 'Status'],             colModel: [                 { name: 'Id', index: 'Id', hidden: true, hidedlg: true },                 { name: 'AccountName', index: 'AccountName', align: "left", resizable: true, search: true, width: 100 },                 { name: 'OnlineName', index: 'OnlineName', align: 'left', sortable: false, width: 80 },                 { name: 'ListingCategoryName', index: 'ListingCategoryName', width: 85, editable: true, hidden: false, edittype: "select", editoptions: { multiple: false, value: eval('(' + catList + ')') }, editrules: { required: false }, formatoptions: { disabled: false} }             ],             jsonReader: {                 root: "List",                 page: "CurrentPage",                 total: "TotalPages",                 records: "TotalRecords",                 userdata: "Errors",                 repeatitems: false,                 id: "0"             },             rowNum: $rows,             rowList: [10, 20, 50, 200, 500, 1000, 2000],             imgpath: jQueryImageRoot,             pager: $(item + 'Pager'),             shrinkToFit: true,             width: 1455,             recordtext: 'Traffic lines',             sortname: 'OrderDate',             viewrecords: true,             sortorder: "asc",             altRows: true,             cellEdit: true,             cellsubmit: "remote",             cellurl: editURL + '?rows=' + $rows + '&page=1',             loadComplete: function() {               },             gridComplete: function() {             },             loadError: function(xhr, st, err) {             },             afterEditCell: function(rowid, cellname, value, iRow, iCol) {                 var select = $(item).find('td.edit-cell select');                 $(item).find('td.edit-cell select option').each(function() {                     var option = $(this);                     var optionId = $(this).val();                     $(lookupData.ListingCategory).each(function() {                         if (this.Id == optionId) {                                                       if (this.OnlineName != $(item).getCell(rowid, 'OnlineName')) {                                 option.remove();                                 return false;                             }                         }                     });                 });             },             search: true,             searchdata: {},             caption: "List of all Traffic lines",             editurl: editURL + '?rows=' + $rows + '&page=1',             hiddengrid: hideGrid   Here is the JSON data returned via the ajax call during the jqGrid function call above (NOTE it must be { async: false}: {"ListingCategory":[{"Id":29,"Name":"Document Imaging & Management","OnlineName":"RF Globalnet"} ,{"Id":1,"Name":"Ancillary Department Hardware","OnlineName":"Healthcare Technology Online"} ,{"Id":2,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":3,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":4,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":5,"Name":"Document Imaging & Management","OnlineName":"Healthcare Technology Online"} ,{"Id":6,"Name":"Document Imaging & Management","OnlineName":"Healthcare Technology Online"} ,{"Id":7,"Name":"EMR/EHR Software","OnlineName":"Healthcare Technology Online"}]} I only need the Id and Name for the drop down list, but the third column in the JSON object is important, it is the only that I match up with the OnlineName in the jqGrid column, and then in the loop during afterEditCell simply remove the ones I don't want the user to see. That's it!

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  • How does Starcraft 2 load it's metadata?

    - by chobok
    Lets say you are playing Starcraft 2 melee map. The game loads the map. Melee maps have the following dependencies: Liberty (Mod) Liberty Multi (Mod) I think the game engine will load the data from Liberty (Mod) first, then from Liberty Multi (Mod). For data that exists in both dependencies, the engine will use the one from Liberty Multi (Mod). Is this correct? Liberty Multi (Mod) is updated with each patch of Starcraft 2. Does the game engine load just the latest version of Liberty Multi (Mod)? or Does the game engine load all the versions and overwrite duplicate data with the latest version?

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  • Page load speeds effect on crawl rate

    - by Sam Pegler
    We've noticed a big drop in the total pages crawled per day on our site, we have no control over the crawl rate in google webmaster tools so it's possible this has been changed by google. However it's a fairly large site and I wouldn't of thought that the crawl rate would've been decreased. What we have noticed though is a sizeable increase in page load times, in my mind this would be the cause. Can anyone else confirm if the crawl rate is directly correlated to page load time? Seems logical, longer page load time, less pages crawled. Any decent documentation on this would be appreciated, I don't normally have any input on SEO so this is new to me.

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  • How to migrate user settings and data to new machine?

    - by torbengb
    I'm new to Ubuntu and recently started using it on my PC. I'm going to replace that PC with a new machine. I want to transfer my data and settings to the nettop. What aspects should I consider? Obviously I want to move my data over. What things am I missing if I only copy the entire home folder? This is a home pc (not corporate) so user rights and other security issues are not a concern, except that the files should be accessible on the new machine! Please take into account that the new machine is a nettop that doesn't have an optical drive and doesn't allow me to hook the old SATA disk into it, so any data transfer must be handled via home network (I can have both the old and the new machine turned on and connected to the home LAN) and I have an USB thumbdrive with limited capacity (2GB). This sounds like it might limit the general applicability, but it would in fact make it more general. I'll make this a wiki topic because there could be several "right" answers. Update: Or so I thought. I don't see a choice for that.

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  • Is it conceivable to have millions of lists of data in memory in Python?

    - by Codemonkey
    I have over the last 30 days been developing a Python application that utilizes a MySQL database of information (specifically about Norwegian addresses) to perform address validation and correction. The database contains approximately 2.1 million rows (43 columns) of data and occupies 640MB of disk space. I'm thinking about speed optimizations, and I've got to assume that when validating 10,000+ addresses, each validation running up to 20 queries to the database, networking is a speed bottleneck. I haven't done any measuring or timing yet, and I'm sure there are simpler ways of speed optimizing the application at the moment, but I just want to get the experts' opinions on how realistic it is to load this amount of data into a row-of-rows structure in Python. Also, would it even be any faster? Surely MySQL is optimized for looking up records among vast amounts of data, so how much help would it even be to remove the networking step? Can you imagine any other viable methods of removing the networking step? The location of the MySQL server will vary, as the application might well be run from a laptop at home or at the office, where the server would be local.

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  • MATLAB: What is an appropriate Data Structure for a Matrix with Random Variable Entries?

    - by user12707
    I'm working in an area that is related to simulation and trying to design a data structure that can include random variables within matrices. I am currently coding in MATLAB. To motivate this let me say I have the following matrix: [a b; c d] I want to find a data structure that will allow for a, b, c, d to be either real numbers or random variables. As an example, let's say that a = 1, b = -1, c = 2 but let d be a normally distributed random variable with mean 20 and SD 40. The data structure that I have in mind will give no value to d. However, I also want to be able to design a function that can take in the structure, simulate an uniform(0,1), obtain a value for d using an inverse CDF and then spit out an actual matrix. I have several ideas to do this (all related to the MATLAB icdf function) but would like to know how more experienced programmers would do it. In this application, it's important that the structure is as "lean" as possible since I will be working with very very large matrices and memory will be an issue.

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  • Load Web Pages Problem- Using Firefox and Chromium

    - by dylan0005
    Basicly my problem emerges when I try to load Facebook and Yahoomail, I don't know why Both browsers Firefox and Chromium don't load these webpages, but this problem only happen with UBUNTU, when I'm in windows no problem. Note: The other webpages like youtube, gmail etc load without any problem. I've tried these following quikcly solutions: -delete cookies, history and Temp files -return the browser to their original settings -desintall and install the browsers -Change the DNS configuration Nothing has been successfull. I need your help guys. What should I do?

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  • Migrating data from Plone to Liferay, or how could I retrieve information from Plone's Data.fs

    - by brandizzi
    Hello, all. I need to migrate data from a Plone-based portal to Liferay. Has anyone some idea on how to do it? Anyway, I am trying to retrieve data from Data.fs and store it in a representation easier to work, such as JSON. To do it, I need to know which objects I should get from Plone's Data.fs. I already got the Products.CMFPlone.Portal.PloneSite instance from the Data.fs, but I cannot get anything from it. I would like to get the PloneSite instance and do something like this: >>> import ZODB >>> from ZODB import FileStorage, DB >>> path = r"C:\Arquivos de programas\Plone\var\filestorage\Data.fs" >>> storage = FileStorage.FileStorage(path) >>> db = DB(storage) >>> conn = db.open() >>> root = conn.root() >>> app = root['Application'] >>> plone_site = app.getChildNodes()[13] # 13 would be index of PloneSite object >>> a = plone_site.get_articles() >>> for article in a: ... print "Title:", a.title ... print "Content:", a.content Title: <some title> Conent: <some content> Title: <some title> Conent: <some content> Of course, it did not need to be so straightforward. I just want some information about the structure of PloneSite and how to recover its data. Has anyone some idea? Thank you in advance!

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  • Using Mapping Models to migrate between Core Data Object Models

    - by westsider
    I have a fairly simply scheme. Essentially, Run <-- Data (where a Run holds a data, e.g., Temperature, sampled from some sort of sensor). Now, it seems that sensors can have more than one measurement (e.g., Temperature and Humidity). So, a single Run could have multiple data samples. Hence, Run <-- Sample and Sample <-- Data. (And for simplicity I am leaving Run <-- Data in place, for now.) If I create a new mapping model, then things generally work - except that no new Samples are created, no relationships are established between Runs and Samples nor between Samples and Datas. I am trying to get mapping model to migrate my model but even the slightest change to the generated mapping model results in Cocoa error 134110. For example, if I take the "Sample" mapping (which has no Source) and set its Source to 'Run' (so that I can set Sample's inverse relationship 'run' appropriately) then the mapping changes its name to "RunToSample". There are two relationships handled in this mapping: data and run. The data property gets set automatically to FUNCTION($manager, "destinationInstancesForEntityMappingNamed:sourceInstances:" , "DataToData", $source.dataSet) Following this example, I set the run property to FUNCTION($manager, "destinationInstancesForEntityMappingNamed:sourceInstances:" , "RunToRun", $source) Similarly, I set the 'sample' property mapping in RunToRun to FUNCTION($manager, "destinationInstancesForEntityMappingNamed:sourceInstances:" , "RunToSample", $source) and the 'sample' property in DataToData to FUNCTION($manager, "destinationInstancesForEntityMappingNamed:sourceInstances:" , "RunToSample", $source.run) So, what, I wonder, is going wrong? I have tried various permutations, such as leaving the 'inverse' relationships unspecified. But I continue to get the same error (134110) regardless. I imagine that this is a lot easier than it seems and that I am missing some fundamental but minor piece. I have also tried subclassing NSEntityMigrationPolicy and overriding -createDestinationInstancesForSourceInstance: but these efforts have met with much the same results. Thanks in advance for any pointers or (relevant :-) advice.

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  • Static Data Structures on Embedded Devices (Android in particular)

    - by Mark
    I've started working on some Android applications and have a question regarding how people normally deal with situations where you have a static data set and have an application where that data is needed in memory as one of the standard java collections or as an array. In my current specific issue i have a spreadsheet with some pre-calculated data. It consists of ~100 rows and 3 columns. 1 Column is a string, 1 column is a float, 1 column is an integer. I need access to this data as an array in java. It seems like i could: 1) Encode in XML - This would be cpu intensive to decode in my experience. 2) build into SQLite database - seems like a lot of overhead for static access to data i only need array style access to in ram. 3) Build into binary blob and read in. (never done this in java, i miss void *) 4) Build a python script to take the CSV version of my data and spit out a java function that adds the values to my desired structure with hard coded values. 5) Store a string array via androids resource mechanism and compute the other 2 columns on application load. In my case the computation would require a lot of calls to Math.log, Math.pow and Math.floor which i'd rather not have to do for load time and battery usage reasons. I mostly work in low power embedded applications in C and as such #4 is what i'm used to doing in these situations. It just seems like it should be far easier to gain access to static data structures in java/android. Perhaps I'm just being too battery usage conscious and in my single case i imagine the answer is that it doesn't matter much, but if every application took that stance it could begin to matter. What approaches do people usually take in this situation? Anything I missed?

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  • Efficient data importing?

    - by Kevin
    We work with a lot of real estate, and while rearchitecting how the data is imported, I came across an interesting issue. Firstly, the way our system works (loosely speaking) is we run a Coldfusion process once a day that retrieves data provided from an IDX vendor via FTP. They push the data to us. Whatever they send us is what we get. Over the years, this has proven to be rather unstable. I am rearchitecting it with PHP on the RETS standard, which uses SOAP methods of retrieving data, which is already proven to be much better than what we had. When it comes to 'updating' existing data, my initial thought was to query only for data that was updated. There is a field for 'Modified' that tells you when a listing was last updated, and the code I have will grab any listing updated within the last 6 hours (give myself a window in case something goes wrong). However, I see a lot of real estate developers suggest creating 'batch' processes that run through all listings regardless of updated status that is constantly running. Is this the better way to do it? Or am I fine with just grabbing the data I know I need? It doesn't make a lot of sense to me to do more processing than necessary. Thoughts?

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  • source of historical stock data

    - by rmeador
    I'm trying to make a stock market simulator (perhaps eventually growing into a predicting AI), but I'm having trouble finding data to use. I'm looking for a (hopefully free) source of historical stock market data. Ideally, it would be a very fine-grained (second or minute interval) data set with price and volume of every symbol on NASDAQ and NYSE (and perhaps others if I get adventurous). Does anyone know of a source for such info? I found this question which indicates Yahoo offers historical data in CSV format, but I've been unable to find out how to get it in a cursory examination of the site linked. I also don't like the idea of downloading the data piecemeal in CSV files... I imagine Yahoo would get upset and shut me off after the first few thousand requests. I also discovered another question that made me think I'd hit the jackpot, but unfortunately that OpenTick site seems to have closed its doors... too bad, since I think they were exactly what I wanted. I'd also be able to use data that's just open/close price and volume of every symbol every day, but I'd prefer all the data if I can get it. Any other suggestions?

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  • Filter of Data in Gridview logical error please using asp.net

    - by RajuBabli Abbasi
    I wanted to filter the Data in asp.net but my Data is not filtering i have some logical error So please help me for this case i will be very thanks full to those who will help me please consider my code and replay me with code if you can so please i am waiting for your replay thanks again my asp.cs file is protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { DisplayStudentInformation(); } } private void DisplayStudentInformation() { string filter = "%" + filterTextBox.Text + "%"; if (filter == String.Empty) filter = "%"; try { using (SqlDataReader reader = DAC.GetCompanyInformation(filter)) {//reader.Read(); StudentGridView.DataSource = reader; StudentGridView.DataBind(); } } catch (SqlException ex) { StatusLabel.Text = ex.Message; } } my .aspx file is asp:Table ID="Tabel" runat ="server" asp:TableRow asp:TableCell asp:Label ID="filterLabel" runat ="server" Text ="Company Name Filter:" AssociatedControlID="filterTextBox" /asp:TableCell asp:TableCell asp:TextBox ID="filterTextBox" runat="server" MaxLength ="50" /asp:TableCell asp:TableCell asp:Button ID="refreshButton" runat ="server" Text ="Filter" CausesValidation="false" / /asp:TableCell /asp:TableRow /asp:Table My DAC file is public static SqlDataReader GetCompanyInformation(string filter) { SqlDataReader reader; string sql = "SELECT * FROM Student WHERE LastName LIKE @prmLastName "; using(SqlCommand command = new SqlCommand (sql,ConnectionManager.GetConnection())) {//In ExecuteReader we pass the CommandBehavior as singleResult because we need the Single result and also passing the close connection when Datais retriev // command.Parameters.Add("@prmLastName", SqlDbType.VarChar, 25).Value = filter; command.Parameters.AddWithValue("@prmLastName", filter); reader = command.ExecuteReader(CommandBehavior.SingleResult | CommandBehavior.CloseConnection); } return reader; } Note:- When i don't use the If(!Ispostback) Condition and simply pass the DisplayStudentInformation(); method in my page load then Data can be filter but with If(!IspostBack ) condition which is also important for updating the data and for other purpose . Data can be filter . Se aim of the expert is that Filter the Data in a gridview using condition of IF(!IspostBack ) means without the removing is post back condition Filter the Data . I have been ask other about this question but no body solve this so please help me i will be very thanks full to you all ok

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  • Architecture for data layer that uses both localStorage and a REST remote server

    - by Zack
    Anybody has any ideas or references on how to implement a data persistence layer that uses both a localStorage and a REST remote storage: The data of a certain client is stored with localStorage (using an ember-data indexedDB adapter). The locally stored data is synced with the remote server (using ember-data RESTadapter). The server gathers all data from clients. Using mathematical sets notation: Server = Client1 ? Client2 ? ... ? ClientN where, in general, a record may not be unique to a certain client. Here are some scenarios: A client creates a record. The id of the record can not set on the client, since it may conflict with a record stored on the server. Therefore a newly created record needs to be committed to the server - receive the id - create the record in localStorage. A record is updated on the server, and as a consequence the data in localStorage and in the server go out of sync. Only the server knows that, so the architecture needs to implement a push architecture (?) Would you use 2 stores (one for localStorage, one for REST) and sync between them, or use a hybrid indexedDB/REST adapter and write the sync code within the adapter? Can you see any way to avoid implementing push (Web Sockets, ...)?

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  • Export large amount of data from Oracle 10G to SQL Server 2005

    - by uniball
    Dear all, I need to export 100 million data rows (avg row length ~ 100 bytes) from Oracle 10G database table into SQL server (over WAN/VLAN with 6MBits/sec capacity) on a regular basis. So far, these are the options that I have tried and a quick summary. Has anyone tried this before? Are there other better options? Which option would be the best in terms of performance and reliability? The time taken has been calculated using tests on smaller amounts of data and then extrapolating it to estimate the time required. Using data import wizard on the SQL server or SSIS packages to import the data. It will take around 150 hours to complete the task. Using Oracle batch job to spool data into a comma-delimited flat-file. Then using SSIS package to FTP this file to the SQL server and then load directly from the flat-file. The issue here is the size of the flat-file which is expected to run in GBs. Although this option is drastically different, I am even considering the option of using Linked Server to query the Oracle data directly at run-time to avoid bringing in data. Performance is a big problem and I have limited control over the Oracle database in terms of creating table indexes. Regards, Uniball

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  • Best practices for encrypting continuous/small UDP data

    - by temp
    Hello everyone, I am having an application where I have to send several small data per second through the network using UDP. The application need to send the data in real-time (no waiting). I want to encrypt these data and insure that what I am doing is as secure as possible. Since I am using UDP, there is no way to use SSL/TLS, so I have to encrypt each packet alone since the protocol is connectionless/unreliable/unregulated. Right now, I am using a 128-bit key derived from a passphrase from the user, and AES in CBC mode (PBE using AES-CBC). I decided to use a random salt with the passphrase to derive the 128-bit key (prevent dictionary attack on the passphrase), and of course use IVs (to prevent statistical analysis for packets). However I am concerned about few things: Each packet contains small amount of data (like a couple of integer values per packet) which will make the encrypted packets vulnerable to known-plaintext attacks (which will result in making it easier to crack the key). Also, since the encryption key is derived from a passphrase, this will make the key space way less (I know the salt will help, but I have to send the salt through the network once and anyone can get it). Given these two things, anyone can sniff and store the sent data, and try to crack the key. Although this process might take some time, once the key is cracked all the stored data will be decrypted, which will be a real problem for my application. So my question is, what is the best practices for sending/encrypting continuous small data using a connectionless protocol (UDP)? Is my way the best way to do it? ...flowed? ...Overkill? ... Please note that I am not asking for a 100% secure solution, as there is no such thing. Cheers

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  • Best practices for encrytping continuous/small UDP data

    - by temp
    Hello everyone, I am having an application where I have to send several small data per second through the network using UDP. The application need to send the data in real-time (on waiting). I want to encrypt these data and insure that what I am doing is as secure as possible. Since I am using UDP, there is no way to use SSL/TLS, so I have to encrypt each packet alone since the protocol is connectionless/unreliable/unregulated. Right now, I am using a 128-bit key derived from a passphrase from the user, and AES in CBC mode (PBE using AES-CBC). I decided to use a random salt with the passphrase to derive the 128-bit key (prevent dictionary attack on the passphrase), and of course use IVs (to prevent statistical analysis for packets). However I am concerned about few things: Each packet contains small amount of data (like a couple of integer values per packet) which will make the encrypted packets vulnerable to known-plaintext attacks (which will result in making it easier to crack the key). Also, since the encryption key is derived from a passphrase, this will make the key space way less (I know the salt will help, but I have to send the salt through the network once and anyone can get it). Given these two things, anyone can sniff and store the sent data, and try to crack the key. Although this process might take some time, once the key is cracked all the stored data will be decrypted, which will be a real problem for my application. So my question is, what is the best practices for sending/encrypting continuous small data using a connectionless protocol (UDP)? Is my way the best way to do it? ...flowed? ...Overkill? ... Please note that I am not asking for a 100% secure solution, as there is no such thing. Cheers

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  • Using data.table to aggregate

    - by dayne
    After multiple suggestions from SO users, I am finally trying to convert my code over to using data.tables. library(data.table) DT <- data.table(plate = paste0("plate",rep(1:2,each=5)), id = rep(c("CTRL","CTRL","ID1","ID2","ID3"),2), val = 1:10) > DT plate id val 1: plate1 CTRL 1 2: plate1 CTRL 2 3: plate1 ID1 3 4: plate1 ID2 4 5: plate1 ID3 5 6: plate2 CTRL 6 7: plate2 CTRL 7 8: plate2 ID1 8 9: plate2 ID2 9 10: plate2 ID3 10 What I would like to do is take the average of DT[,val] by plate when the id is "CTRL". I would normally aggregate the data frame, then use match to map the values back to a new column, 'ctrl'. Using the data.table package I can get: DT[id=="CTRL",ctrl:=mean(val),by=plate] > DT plate id val ctrl 1: plate1 CTRL 1 1.5 2: plate1 CTRL 2 1.5 3: plate1 ID1 3 NA 4: plate1 ID2 4 NA 5: plate1 ID3 5 NA 6: plate2 CTRL 6 6.5 7: plate2 CTRL 7 6.5 8: plate2 ID1 8 NA 9: plate2 ID2 9 NA 10: plate2 ID3 10 NA What I need is really: DT <- data.table(plate = paste0("plate",rep(1:2,each=5)), id = rep(c("CTRL","CTRL","ID1","ID2","ID3"),2), val = 1:10, ctrl = rep(c(1.5,6.5),each=5)) > DT plate id val ctrl 1: plate1 CTRL 1 1.5 2: plate1 CTRL 2 1.5 3: plate1 ID1 3 1.5 4: plate1 ID2 4 1.5 5: plate1 ID3 5 1.5 6: plate2 CTRL 6 6.5 7: plate2 CTRL 7 6.5 8: plate2 ID1 8 6.5 9: plate2 ID2 9 6.5 10: plate2 ID3 10 6.5 Eventually I would like to use much more complicated selections of the values, but I do not know how to select specific values, run some function, then map those values back to the appropriate row using data frames.

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  • Can you change an AWS Elastic Load Balancer health check without causing instances to go out of service?

    - by Anton I. Sipos
    For a number of reasons I need to change the health check URL of a live site behind an ELB. The ELB is configured for health checks every 30 seconds, with a healthy threshold of 2 and unhealthy threshold of 2. I need to ensure I make this change with no outage. If I make the change to the health check URL, and assuming the URL checks successfully, will the instances stay healthy on the load balancer, or will they go out of service until they succeed 2 health checks (in 1 minute)?

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  • Is there anyway way to speed up Exchange 2007's Load Generator tool?

    - by JohnM
    I'm running Load Generator to test our new deployment before going live and the initialization process has been running for two days and is only at 25% for ~58000 user test. Does anyone know of a way to speed up this process? Surely it shouldn't take this long. Currently, I've got it running with one master and two remote servers and they aren't peaking out on CPU or Network utilization. Any help you could provide would be greatly appreciated.

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  • How can I set up a load balancer to direct all Search Engine Bot traffic to one server?

    - by Ryan
    We have a simple load balancer set up on Rackspace to 3 web server nodes. After reviewing our traffic and expenses, the largest bandwidth hog is Google Bot. Since on Rackspace we pay for bandwidth by the byte, we'd like to direct all traffic from GoogleBot to another host (MediaTemple) with unlimited bandwidth. We think this would cut our hosting bill several thousand dollars a month. Is this possible? Advisable?

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