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• semi dynamic cdn

  - by dwi kristianto

  i'm developing couple of websites using php (directory script, etc.) and wordpress as cms. i need to improve its performance, by using cdn for static files (css, js, images). the problem is, css and javascript files are generated on the fly. i did that due to yahoo and some expert advice to combine the files into one file. also changing basic color of css files. for the time being, i use couple of small vps but still its not fast enough. i already contact maxcdn and the support guy said that they dont have such kind of services. what i need is: a cdn that will serve the request from user/visitor and there's no file in local disk, the cdn will redirect/fetch it from another domain/server. in vps, it could be done easily using combination of .htaccess and php, but NOT in the cdn. most of cdn only support purely static files. is there any such cdn that will server semi-dynamic files?

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• Where to find algorithms for standard math functions?

  - by dsimcha

  I'm looking to submit a patch to the D programming language standard library that will allow much of std.math to be evaluated at compile time using the compile-time function evaluation facilities of the language. Compile-time function evaluation has several limitations, the most important ones being: You can't use assembly language. You can't call C code or code for which the source is otherwise unavailable. Several std.math functions violate these and compile-time versions need to be written. Where can I get information on good algorithms for computing things such as logarithms, exponents, powers, and trig functions? I prefer just high level descriptions of algorithms to actual code, for two reasons: To avoid legal ambiguity and the need to make my code look "different enough" from the source to make sure I own the copyright. I want simple, portable algorithms. I don't care about micro-optimization as long as they're at least asymptotically efficient. Edit: D's compile time function evaluation model allows floating point results computed at compile time to differ from those computed at runtime anyhow, so I don't care if my compile-time algorithms don't give exactly the same result as the runtime version as long as they aren't less accurate to a practically significant extent.

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• Sorting GridView Formed With Data Set

  - by nani

  Following Code is for Sorting GridView Formed With DataSet Source: http://www.highoncoding.com/Articles/176_Sorting_GridView_Manually_.aspx But it is not displaying any output. There is no problem in sql connection. I am unable to trace the error, please help me. Thank You. public partial class _Default : System.Web.UI.Page { private const string ASCENDING = " ASC"; private const string DESCENDING = " DESC"; private DataSet GetData() { SqlConnection cnn = new SqlConnection("Server=localhost;Database=Northwind;Trusted_Connection=True;"); SqlDataAdapter da = new SqlDataAdapter("SELECT TOP 5 firstname,lastname,hiredate FROM EMPLOYEES", cnn); DataSet ds = new DataSet(); da.Fill(ds); return ds; } public SortDirection GridViewSortDirection { get { if (ViewState["sortDirection"] == null) ViewState["sortDirection"] = SortDirection.Ascending; return (SortDirection)ViewState["sortDirection"]; } set { ViewState["sortDirection"] = value; } } protected void GridView1_Sorting(object sender, GridViewSortEventArgs e) { string sortExpression = e.SortExpression; if (GridViewSortDirection == SortDirection.Ascending) { GridViewSortDirection = SortDirection.Descending; SortGridView(sortExpression, DESCENDING); } else { GridViewSortDirection = SortDirection.Ascending; SortGridView(sortExpression, ASCENDING); } } private void SortGridView(string sortExpression, string direction) { // You can cache the DataTable for improving performance DataTable dt = GetData().Tables[0]; DataView dv = new DataView(dt); dv.Sort = sortExpression + direction; GridView1.DataSource = dv; GridView1.DataBind(); } } aspx page asp:GridView ID="GridView1" runat="server" AllowSorting="True" OnSorting="GridView1_Sorting" /asp:GridView

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• Understanding OOP Principles in passing around objects/values

  - by Hans

  I'm not quite grokking a couple of things in OOP and I'm going to use a fictional understanding of SO to see if I can get help understand. So, on this page we have a question. You can comment on the question. There are also answers. You can comment on the answers. Question - comment - comment - comment Answer -comment Answer -comment -comment -comment Answer -comment -comment So, I'm imagining a very high level understanding of this type of system (in PHP, not .Net as I am not yet familiar with .Net) would be like: $question = new Question; $question->load($this_question_id); // from the URL probably echo $question->getTitle(); To load the answers, I imagine it's something like this ("A"): $answers = new Answers; $answers->loadFromQuestion($question->getID()); // or $answers->loadFromQuestion($this_question_id); while($answer = $answers->getAnswer()) { echo $answer->showFormatted(); } Or, would you do ("B"): $answers->setQuestion($question); // inject the whole obj, so we have access to all the data and public methods in $question $answers->loadFromQuestion(); // the ID would be found via $this->question->getID() instead of from the argument passed in while($answer = $answers->getAnswer()) { echo $answer->showFormatted(); } I guess my problem is, I don't know when or if I should be passing in an entire object, and when I should just be passing in a value. Passing in the entire object gives me a lot of flexibility, but it's more memory and subject to change, I'd guess (like a property or method rename). If "A" style is better, why not just use a function? OOP seems pointless here. Thanks, Hans

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• Which Javascript framework (jQuery vs Dojo vs ... )?

  - by cletus

  There are a few Javascript frameworks/toolets out there, such as: jQuery; Dojo; Prototype; YUI; MooTools; ExtJS; SmartClient; and others I'm sure. It certainly seems that jQuery is ascendant in terms of mindshare at the moment. For example, Microsoft (ASP.NET MVC) and Nokia will use it. I also found this this performance comparison of Dojo, jQuery, MooTools and Prototype (Edit: Updated Comparison), which looks highly favourable to Dojo and jQuery. Now my previous experience with Javascript has been the old school HTML + Javascript most of us have done and RIA frameworks like Google Web Toolkit ("GWT") and Ext-GWT, which were a fairly low-stress entry into the Ajax world for someone from a Java background, such as myself. But, after all this, I find myself leaning towards the more PHP + Ajax type solution, which just seems that much more lightweight. So I've been looking into jQuery and I really like it's use of commands, the use of fluent interfaces and method chaining, it's cross-browser CSS selector superset, the fact that it's lightweight and extensible, the brevity of the syntax, unobtrusive Javascript and the plug-in framework. Now obviously many of these aren't unique to jQuery but on the basis that some things are greater than their sum of parts, it just seems that it all fits together and works well. So jQuery seems to have a lot going for it and it looks to the frontrunner for what I choose to concentrate on. Is there anything else I should be aware of or any particular reasons not to choose it or to choose something else? EDIT: Just wanted to add this trend comparison of Javascript frameworks.

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• Which technology is best suited to store and query a huge readonly graph?

  - by asmaier

  I have a huge directed graph: It consists of 1.6 million nodes and 30 million edges. I want the users to be able to find all the shortest connections (including incoming and outgoing edges) between two nodes of the graph (via a web interface). At the moment I have stored the graph in a PostgreSQL database. But that solution is not very efficient and elegant, I basically need to store all the edges of the graph twice (see my question PostgreSQL: How to optimize my database for storing and querying a huge graph). It was suggested to me to use a GraphDB like neo4j or AllegroGraph. However the free version of AllegroGraph is limited to 50 million nodes and also has a very high-level API (RDF), which seems too powerful and complex for my problem. Neo4j on the other hand has only a very low level API (and the python interface is not mature yet). Both of them seem to be more suited for problems, where nodes and edges are frequently added or removed to a graph. For a simple search on a graph, these GraphDBs seem to be too complex. One idea I had would be to "misuse" a search engine like Lucene for the job, since I'm basically only searching connections in a graph. Another idea would be, to have a server process, storing the whole graph (500MB to 1GB) in memory. The clients could then query the server process and could transverse the graph very quickly, since the graph is stored in memory. Is there an easy possibility to write such a server (preferably in Python) using some existing framework? Which technology would you use to store and query such a huge readonly graph?

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• Can pdflatex (or any tex package) automatically rescale included images which have been reduced in s

  - by drfrogsplat

  I'm writing my thesis in LaTeX, generating it with pdflatex. I have a large number of figures, many of which are bitmaps (as opposed to SVG) in PNG/JPEG format. I've generally created them to be fairly high resolution (say 1600x1200-ish) to ensure that whatever size they end up in the document, they'll be at least 300dpi when printed. As I'm writing/laying out the document, I'm including graphics (using \includegraphics from the graphicx package) and setting widths/heights as appropriate (e.g. subfigures are quite small). I don't need the images to be any more than about 300 dpi at best, so where I have shrunk a 1600x1200 image down to say 5cm, the image is now at 800 dpi. So despite including some very small (on the page) images, the PDF is becoming quite large. Is there a way to tell pdflatex or graphicx (or something else involved?) to convert all images to a maximum of 300 dpi, based on the dimensions I'm setting with say \includegraphics[width=2in]{filename}? i.e. so it scales the image to a max of 600x600 pixels as it includes it in the PDF (leaving the original file untouched). I know I can resize the original images with various command line applications, and include the pre-resized versions, but given the images vary in size considerably, it wouldn't be as simple as making sure they're all 300dpi for a constant printed size. It'd also be nice to be able to easily create different versions of PDFs (web vs final print) without resizing images manually, so that the 'web' PDF capped images at say 72-100 dpi while the final print one could cap at 600 (if at all).

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• Zend php memory memory_limit

  - by RepDetec

  All, I am working on a Zend Framework based web application. We keep encountering out of memory errors on our dev server: Allowed memory size of XXXX bytes exhausted (tried YYYY... We keep increasing memory_limit in php.ini, but it is now up over 1000 megs. What is a normal memory_limit value? What are the usual suspects in php/Zend for running out of memory? We are using the Propel ORM. Thanks for all of the help! Update I cannot reproduce this error in my windows environment. If I set memory_limit low (say 16M), I get the same error, but the "tried to allocate" amount is always something reasonable. For example: (tried to allocate 13344 bytes) If I set the memory very low on the (Fedora 9) server (such as 16M), I get the same thing. consistent, reasonable out of memory errors. However, even when the memory limit is set very high on our server (128M, for example), maybe once a week, I will get an crazy huge memory error: (tried to allocate 1846026201 bytes). I don't know if that might shed any more light onto what is going on. We are using propel 1.5. It sounds like the actual release is going to come out later this month, but it doesn't look like anyone else is having this problem with it anyway. I don't know that Propel is the problem. We are using Zend Server with php 5.2 on the Linux box, and 5.3 locally. Any more ideas? I have a ticket out to get Xdebug installed on the Linux box. Thanks, -rep

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• Is there added overhead to looking up a column in a DataTable by name rather than by index?

  - by Ben McCormack

  In a DataTable object, is there added overhead to looking up a column value by name thisRow("ColumnA") rather than by the column index thisRow(0)? In which scenarios might this be an issue. I work on a team that has lots of experience writing VB6 code and I noticed that didn't do column lookups by name for DataTable objects or data grids. Even in .NET code, we use a set of integer constants to reference column names in these types of objects. I asked our team lead why this was so, and he mentioned that in VB6, there was a lot of overhead in looking up data by column name rather than by index. Is this still true for .NET? Example code (in VB.NET, but same applies to C#): Public Sub TestADOData() Dim dt As New DataTable 'Set up the columns in the DataTable ' dt.Columns.Add(New DataColumn("ID", GetType(Integer))) dt.Columns.Add(New DataColumn("Name", GetType(String))) dt.Columns.Add(New DataColumn("Description", GetType(String))) 'Add some data to the data table ' dt.Rows.Add(1, "Fred", "Pitcher") dt.Rows.Add(3, "Hank", "Center Field") 'Method 1: By Column Name ' For Each r As DataRow In dt.Rows Console.WriteLine( _ "{0,-2} {1,-10} {2,-30}", r("ID"), r("Name"), r("Description")) Next Console.WriteLine() 'Method 2: By Column Name ' For Each r As DataRow In dt.Rows Console.WriteLine("{0,-2} {1,-10} {2,-30}", r(0), r(1), r(2)) Next End Sub Is there an case where method 2 provides a performance advantage over method 1?

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• Change Data Capture or Change Tracking - Same as Traditional Audit Trail Table?

  - by HardCode

  Before I delve into the abyss of Microsoft documentation any deeper, I'd like to know if someone experienced with Change Data Capture and Change Tracking know if one or both of these can be used to replace the traditional ... "Audit trail table copy of the 'real table' (all of the fields of the original table, plus date/time, user ID, and DML action field) inserted into by Triggers" ... setup for a database table audit trail, where the trigger populates the audit trail table (which is all manual work). The MSDN overview documentation explains at a high level what Change Data Capture and Change Tracking are, but it isn't clear enough to me, and doesn't state outright, that these tools can be used to replace the traditional audit trail tables we've made so often. Can someone with any experience using Change Data Capture and Change Tracking save me a lot of time, or confirm that I am spending time looking at the right tool? The critical part of our audit trail is capturing all changes to a table's fields (on INSERT, UPDATE, DELETE), when it happened, and who did it. These changes are commonly provided to an end user chronologically via an audit trail report. Which is another question ... Change Data Capture or Change Tracking is the solution, I'd assume that this data can be queried just like data from a normal table? EDIT: I need a permanent audit trail, irregardless of time. I see that Change Data Capture has to do with the transaction logs, so this sounds finite to me.

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• How to deal with recursive dependencies between static libraries using the binutils linker?

  - by Jack Lloyd

  I'm porting an existing system from Windows to Linux. The build is structured with multiple static libraries. I ran into a linking error where a symbol (defined in libA) could not be found in an object from libB. The linker line looked like g++ test_obj.o -lA -lB -o test The problem of course being that by the time the linker finds it needs the symbol from libA, it has already passed it by, and does not rescan, so it simply errors out even though the symbol is there for the taking. My initial idea was of course to simply swap the link (to -lB -lA) so that libA is scanned afterwards, and any symbols missing from libB that are in libA are picked up. But then I find there is actually a recursive dependency between libA and libB! I'm assuming the Visual C++ linker handles this in some way (does it rescan by default?). Ways of dealing with this I've considered: Use shared objects. Unfortunately this is undesirable from the perspective of requiring PIC compliation (this is performance sensitive code and losing %ebx to hold the GOT would really hurt), and shared objects aren't needed. Build one mega ar of all of the objects, avoiding the problem. Restructure the code to avoid the recursive dependency (which is obviously the Right Thing to do, but I'm trying to do this port with minimal changes). Do you have other ideas to deal with this? Is there some way I can convince the binutils linker to perform rescans of libraries it has already looked at when it is missing a symbol?

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• How to implement properly plugins in C#?

  - by MartyIX

  I'm trying to add plugins to my game and what I'm trying to implement is this: Plugins will be either mine or 3rd party's so I would like a solution where crashing of the plugin would not mean crashing of the main application. Methods of plugins are called very often (for example because of drawing of game objects). What I've found so far: 1) http://www.codeproject.com/KB/cs/pluginsincsharp.aspx - simple concept that seems like it should work nicely. Since plugins are used in my game for every round I would suffice to add the Restart() method and if a plugin is no longer needed Unload() method + GC should take care of that. 2) http://mef.codeplex.com/Wikipage - Managed Extensibility Framework - my program should work on .NET 3.5 and I don't want to add any other framework separately I want to write my plugin system myself. Therefore this solution is out of question. 3) Microsoft provides: http://msdn.microsoft.com/en-us/library/system.addin.aspx but according to a few articles I've read it is very complex. 4) Different AppDomains for plugins. According to Marc Gravell ( http://stackoverflow.com/questions/665668/usage-of-appdomain-in-c ) different AppDomains allow isolation. Unloading of plugins would be easy. What would the performance load be? I need to call methods of plugins very often (to draw objects for example). Using Application Domains - http://msdn.microsoft.com/en-us/library/yb506139.aspx A few tutorials on java2s.com Could you please comment on my findings? New approaches are also welcomed! Thanks!

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• Non-blocking TCP buffer issues.

  - by Poni

  Hi! I think I'm in a problem. I have two TCP apps connected to each other which use winsock I/O completion ports to send/receive data (non-blocking sockets). Everything works just fine until there's a data transfer burst. The sender starts sending incorrect/malformed data. I allocate the buffers I'm sending on the stack, and if I understand correctly, that's a wrong to do, because these buffers should remain as I sent them until I get the "write complete" notification from IOCP. Take this for example: void some_function() { char cBuff[1024]; // filling cBuff with some data WSASend(...); // sending cBuff, non-blocking mode // filling cBuff with other data WSASend(...); // again, sending cBuff // ..... and so forth! } If I understand correctly, each of these WSASend() calls should have its own unique buffer, and that buffer can be reused only when the send completes. Correct? Now, what strategies can I implement in order to maintain a big sack of such buffers, how should I handle them, how can I avoid performance penalty, etc'? And, if I am to use buffers that means I should copy the data to be sent from the source buffer to the temporary one, thus, I'd set SO_SNDBUF on each socket to zero, so the system will not re-copy what I already copied. Are you with me? Please let me know if I wasn't clear.

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• Maximum page fetch with maximum bandwith

  - by Ehsan

  Hi I want to create an application like a spider I've implement fetching page as the following code in multi-thread application but there is two problem 1) I want to use my maximum bandwidth to send/receive request, how should I config my request to do so (Like Download Accelerator application and the like) cause I heard the normal application will use 66% of the available bandwidth. 2) I don't know what exactly HttpWebRequest.KeepAlive do, but as its name implies I think i can create a connection to a website and without closing the connection sending another request to that web site using existing connection. does it boost performance or Im wrong ?? public PageFetchResult Fetch() { PageFetchResult fetchResult = new PageFetchResult(); try { HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(URLAddress); HttpWebResponse resp = (HttpWebResponse)req.GetResponse(); Uri requestedURI = new Uri(URLAddress); Uri responseURI = resp.ResponseUri; string resultHTML = ""; byte[] reqHTML = ResponseAsBytes(resp); if (!string.IsNullOrEmpty(FetchingEncoding)) resultHTML = Encoding.GetEncoding(FetchingEncoding).GetString(reqHTML); else if (!string.IsNullOrEmpty(resp.CharacterSet)) resultHTML = Encoding.GetEncoding(resp.CharacterSet).GetString(reqHTML); req.Abort(); resp.Close(); fetchResult.IsOK = true; fetchResult.ResultHTML = resultHTML; } catch (Exception ex) { fetchResult.IsOK = false; fetchResult.ErrorMessage = ex.Message; } return fetchResult; }

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• chrome extension login security with iframe

  - by Weaver

  I should note, I'm not a chrome extension expert. However, I'm looking for some advice or high level solution to a security concern I have with my chrome extension. I've searched quite a bit but can't seem to find a concrete answer. The situation I have a chrome extension that needs to have the user login to our backend server. However, it was decided for design reasons that the default chrome popup balloon was undesirable. Thus I've used a modal dialog and jquery to make a styled popup that is injected with content scripts. Hence, the popup is injected into the DOM o the page you are visiting. The Problem Everything works, however now that I need to implement login functionality I've noticed a vulnerability: If the site we've injected our popup into knows the password fields ID they could run a script to continuously monitor the password and username field and store that data. Call me paranoid, but I see it as a risk. In fact,I wrote a mockup attack site that can correctly pull the user and password when entered into the given fields. My devised solution I took a look at some other chrome extensions, like Buffer, and noticed what they do is load their popup from their website and, instead, embed an iFrame which contains the popup in it. The popup would interact with the server inside the iframe. My understanding is iframes are subject to same-origin scripting policies as other websites, but I may be mistaken. As such, would doing the same thing be secure? TLDR To simplify, if I embedded an https login form from our server into a given DOM, via a chrome extension, are there security concerns to password sniffing? If this is not the best way to deal with chrome extension logins, do you have suggestions with what is? Perhaps there is a way to declare text fields that javascript can simply not interact with? Not too sure! Thank you so much for your time! I will happily clarify anything required.

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• How do you concat multiple rows into one column in SQL Server?

  - by Jason

  I've searched high and low for the answer to this, but I can't figure it out. I'm relatively new to SQL Server and don't quite have the syntax down yet. I have this datastructure (simplified): Table "Users" | Table "Tags": UserID UserName | TagID UserID PhotoID 1 Bob | 1 1 1 2 Bill | 2 2 1 3 Jane | 3 3 1 4 Sam | 4 2 2 ----------------------------------------------------- Table "Photos": | Table "Albums": PhotoID UserID AlbumID | AlbumID UserID 1 1 1 | 1 1 2 1 1 | 2 3 3 1 1 | 3 2 4 3 2 | 5 3 2 | I'm looking for a way to get the all the photo info (easy) plus all the tags for that photo concatenated like CONCAT(username, ', ') AS Tags of course with the last comma removed. I'm having a bear of a time trying to do this. I've tried the method in this article but I get an error when I try to run the query saying that I can't use DECLARE statements... do you guys have any idea how this can be done? I'm using VS08 and whatever DB is installed in it (I normally use MySQL so I don't know what flavor of DB this really is... it's an .mdf file?)

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• Is it possible that a single-threaded program is executed simultaneously on more than one CPU core?

  - by Wolfgang Plaschg

  When I run a single-threaded program that i have written on my quad core Intel i can see in the Windows Task Manager that actually all four cores of my CPU are more or less active. One core is more active than the other three, but there is also activity on those. There's no other program (besided the OS kernel of course) running that would be plausible for that activitiy. And when I close my program all activity an all cores drops down to nearly zero. All is left is a little "noise" on the cores, so I'm pretty sure all the visible activity comes directly or indirectly (like invoking system routines) from my program. Is it possible that the OS or the cores themselves try to balance some code or execution on all four cores, even it's not a multithreaded program? Do you have any links that documents this technique? Some infos to the program: It's a console app written in Qt, the Task Manager states that only one thread is running. Maybe Qt uses threads, but I don't use signals or slots, nor any GUI. Link to Task Manager screenshot: http://img97.imageshack.us/img97/6403/taskmanager.png This question is language agnostic and not tied to Qt/C++, i just want to know if Windows or Intel do to balance also single-threaded code on all cores. If they do, how does this technique work? All I can think of is, that kernel routines like reading from disk etc. is scheduled on all cores, but this won't improve performance significantly since the code still has to run synchronous to the kernel api calls. EDIT Do you know any tools to do a better analysis of single and/or multi-threaded programs than the poor Windows Task Manager?

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• How do we greatly optimize our MySQL database (or replace it) when using joins?

  - by jkaz

  Hi there, This is the first time I'm approaching an extremely high-volume situation. This is an ad server based on MySQL. However, the query that is used incorporates a lot of JOINs and is generally just slow. (This is Rails ActiveRecord, btw) sel = Ads.find(:all, :select = '*', :joins = "JOIN campaigns ON ads.campaign_id = campaigns.id JOIN users ON campaigns.user_id = users.id LEFT JOIN countries ON countries.campaign_id = campaigns.id LEFT JOIN keywords ON keywords.campaign_id = campaigns.id", :conditions = [flashstr + "keywords.word = ? AND ads.format = ? AND campaigns.cenabled = 1 AND (countries.country IS NULL OR countries.country = ?) AND ads.enabled = 1 AND campaigns.dailyenabled = 1 AND users.uenabled = 1", kw, format, viewer['country'][0]], :order = order, :limit = limit) My questions: Is there an alternative database like MySQL that has JOIN support, but is much faster? (I know there's Postgre, still evaluating it.) Otherwise, would firing up a MySQL instance, loading a local database into memory and re-loading that every 5 minutes help? Otherwise, is there any way I could switch this entire operation to Redis or Cassandra, and somehow change the JOIN behavior to match the (non-JOIN-able) nature of NoSQL? Thank you!

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• Application passwords and SQLite security

  - by Bryan

  I have been searching on google for information regarding application passwords and SQLite security for some time, and nothing that I have found has really answered my questions. Here is what I am trying to figure out: 1) My application is going to have an optional password activity that will be called when the application is first opened. My questions for this are a) If I store the password via android preference or SQLite database, how can I ensure security and privacy for the password, and b) how should password recovery be handled? Regarding b) from above, I have thought about requiring an email address when the password feature is enabled, and also a password hint question for use when requesting password recovery. Upon successfully answering the hint question, the password is then emailed to the email address that was submitted. I am not completely confident in the security and privacy of the email method, especially if the email is sent when the user is connected to an open, public wireless network. 2) My application will be using an SQLite database, which will be stored on the SD card if the user has one. Regardless of whether it is stored on the phone or the SD card, what options do I have for data encryption, and how does that affect the application performance? Thanks in advance for time taken to answer these questions. I think that there may be other developers struggling with the same concerns.

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• Experiences with (free) embedded TCP / IP stacks?

  - by Dan

  Does anyone have especially good (or bad) experiences with any of the following embedded TCP / IP stacks? uIP lwIP Bentham's TCP/IP Lean implementation The TCP/IP stack from this book My needs are for a solid, easy-to-port stack. Code size isn't terribly important, performance is relatively important, but ease of use & porting is very important. The system will probably use an RTOS, that hasn't been decided, but in my experience most stacks can be used with or without an RTOS. Most likely the platform will be an ARM variant (ARM7 or CM3 in all likelihood). Not too concerned about bolting the stack to the Ethernet driver, so that isn't a big priority in the selection. I'm not terribly interested in extracting a stack out of an OS, such as Linux, RTEMS, etc. I'm also not interested in commercial offerings such as Interniche, Micrium, etc... The stack doesn't need all sorts of bells & whistles, doesn't need IPv6, and I don't need any stuff on top of it (web servers, FTP servers, etc..) In fact it's possible that I'll only use UDP, although I can envision a couple scenarios where TCP would be preferable. Experiences with other stacks I've missed are of course also very much of interest. Thanks for your time & input.

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• Pitfalls and practical Use-Cases: Toplink, Hibernate, Eclipse Link, Ibatis ...

  - by Martin K.

  I worked a lot with Hibernate as my JPA implementation. In most cases it works fine! But I have also seen a lot of pitfalls: Remoting with persisted Objects is difficult, because Hibernate replaces the Java collections with its own collection implementation. So the every client must have the Hibernate .jar libraries. You have to take care on LazyLoading exceptions etc. One way to get around this problem is the use of webservices. Dirty checking is done against the Database without any lock. "Delayed SQL", causes that the data access isn't ACID compliant. (Lost data...) Implict Updates So we don't know if an object is modified or not (commit causes updates). Are there similar issues with Toplink, Eclipse Link and Ibatis? When should I use them? Have they a similar performance? Are there reasons to choose Eclipse Link/Toplink... over Hibernate?

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• How to invalidate cache when benchmarking?

  - by Michael Buen

  I have this code, that when swapping the order of UsingAs and UsingCast, their performance also swaps. using System; using System.Diagnostics; using System.Linq; using System.IO; class Test { const int Size = 30000000; static void Main() { object[] values = new MemoryStream[Size]; UsingAs(values); UsingCast(values); Console.ReadLine(); } static void UsingCast(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = 0; foreach (object o in values) { if (o is MemoryStream) { var m = (MemoryStream)o; sum += (int)m.Length; } } sw.Stop(); Console.WriteLine("Cast: {0} : {1}", sum, (long)sw.ElapsedMilliseconds); } static void UsingAs(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = 0; foreach (object o in values) { if (o is MemoryStream) { var m = o as MemoryStream; sum += (int)m.Length; } } sw.Stop(); Console.WriteLine("As: {0} : {1}", sum, (long)sw.ElapsedMilliseconds); } } Outputs: As: 0 : 322 Cast: 0 : 281 When doing this... UsingCast(values); UsingAs(values); ...Results to this: Cast: 0 : 322 As: 0 : 281 When doing just this... UsingAs(values); ...Results to this: As: 0 : 322 When doing just this: UsingCast(values); ...Results to this: Cast: 0 : 322 Aside from running them independently, how to invalidate the cache so the second code being benchmarked won't receive the cached memory of first code? Benchmarking aside, just loved the fact that modern processors do this caching magic :-)

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• What type of webapp is the sweet spot for Scala's Lift framework?

  - by ajay

  What kind of applications are the sweet spot for Scala's lift web framework. My requirements: Ease of development and maintainability Ready for production purposes. i.e. good active online community, regular patches and updates for security and performance fixes etc. Framework should survive a few years. I don't want to write a app in a framework for which no updates/patches are available after 1 year. Has good UI templating engines Interoperation with Java (Scala satisfies this arleady. Just mentioning here for completeness sake) Good component oriented development. Time required to develop should be proportion to the complexity of web application. Should not be totally configuration based. I hate it when code gets automatically generated for me and does all sorts of magic under the hood. That is a debugging nightmare. Amount of Lift knowledge required to develop a webapp should be proportional to the complexity of the web application. i.e I should't have to spend 10+ hours learning Lift just to develop a simple TODO application. (I have knowledge of Databases, Scala) Does Lift satisfy these requirements?

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• Mouse bugginess - SWFObject, Firefox 3 for Mac, and Flash

  - by justinbach

  I'm pulling my hair out over a problem I'm encountering on Firefox 3.5 & 3.6 on OS X. I'm using SWFobject to embed an AmMap of the US, which has rollover tooltips for various states. The rollovers are working fine in every other browser I've tested, but they're very buggy on FF for Mac--most of the time they don't show up at all, but if I persistently click a state that's supposed to have a hover event, I might catch a glimpse of the tooltip. Here's the code for the SWFObject embed (incidentally, this isn't being done in the document head due to templating reasons). The reason that the SWFObject initialization is wrapped in Jquery's document.ready handler is that the swf wasn't even appearing in FF 3.5.9 for mac until I added that in: $(document).ready(function() { var params = { quality: "high", scale: "noscale", allowscriptaccess: "always", allowfullscreen: "true", bgcolor: "#FFFFFF", base:"/<?php print LANG . "/locations/" ?>" }; var flashvars = { path: "", settings_file: "mapsettings", data_file:"mapdata" }; var attributes = { id: "flashmap", name: "flashmap" }; swfobject.embedSWF("/assets/flash/ammap.swf", "flashmap", "470", "300", "8", null, flashvars, params, attributes); }); Any feedback would be greatly appreciate...site goes live in 48 hours! Thanks!

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• Several Small, Specific, MySQL Query Cache Questions

  - by Robbie

  I've look all over the web and in the questions asked here about MySQL caching and most of them seem very non-specific about a couple of questions that I have about performance and MySQL query caching. Specifically I want answers to these questions, assume for all questions that I have the query cache enabled and it is of type 2, or "DEMAND": Is the query cache per table, per database, or per server? Meaning if I have the cache size set to X and have T tables and D databases will I be caching TX, DX, or X amount of data? If I have table T1 which I regularly use the SQL_CACHE hint on for SELECT queries and table T2 which I never do, when I query T2 with a SELECT query will it check through the cache first before performing the query? *Note: I don't want to use the SQL_NO_CACHE for all T2 queries.* Assume the same situation as in question 2. If I alter (INSERT, DELETE) table T2 will any processing be done on the cache? For answers to 2 and 3, is this processing time negligible if T2 is constantly being altered and is the target of a majority of my SELECT queries?

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