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• SQL/Schema comparison and upgrade

  - by Workshop Alex

  I have a simple situation. A large organisation is using several different versions of some (desktop) application and each version has it's own database structure. There are about 200 offices and each office will have it's own version, which can be one of 7 different ones. The company wants to upgrade all applications to the latest versions, which will be version 8. The problem is that they don't have a separate database for each version. Nor do they have a separate database for each office. They have one single database which is handled by a dedicated server, thus keeping things like management and backups easier. Every office has it's own database schema and within the schema there's the whole database structure for their specific application version. As a result, I'm dealing with 200 different schema's which need to be upgraded, each with 7 possible versions. Fortunately, every schema knows the proper version so checking the version isn't difficult. But my problem is that I need to create upgrade scripts which can upgrade from version 1 to version 2 to version 3 to etc... Basically, all schema's need to be bumped up one version until they're all version 8. Writing the code that will do this is no problem. the challenge is how to create the upgrade script from one version to the other? Preferably with some automated tool. I've examined RedGate's SQL Compare and Altova's DatabaseSpy but they're not practical. Altova is way too slow. RedGate requires too much processing afterwards, since the generated SQL Script still has a few errors and it refers to the schema name. Furthermore, the code needs to become part of a stored procedure and the code generated by RedGate doesn't really fit inside a single procedure. (Plus, it's doing too much transaction-handling, while I need everything within a single transaction. I have been considering using another SQL Comparison tool but it seems to me that my case is just too different from what standard tools can deliver. So I'm going to write my own comparison tool. To do this, I'll be using ADOX with Delphi to read the catalogues for every schema version in the database, then use this to write the SQL Statements that will need to upgrade these schema's to their next version. (Comparing 1 with 2, 2 with 3, 3 with 4, etc.) I'm not unfamiliar with generating SQL-Script-Generators so I don't expect too many problems. And I'll only be upgrading the table structures, not any of the other database objects. So, does anyone have some good tips and tricks to apply when doing this kind of comparisons? Things to be aware of? Practical tips to increase speed?

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• Migrating from hand-written persistence layer to ORM

  - by Sergey Mikhanov

  Hi community, We are currently evaluating options for migrating from hand-written persistence layer to ORM. We have a bunch of legacy persistent objects (~200), that implement simple interface like this: interface JDBC { public long getId(); public void setId(long id); public void retrieve(); public void setDataSource(DataSource ds); } When retrieve() is called, object populates itself by issuing handwritten SQL queries to the connection provided using the ID it received in the setter (this usually is the only parameter to the query). It manages its statements, result sets, etc itself. Some of the objects have special flavors of retrive() method, like retrieveByName(), in this case a different SQL is issued. Queries could be quite complex, we often join several tables to populate the sets representing relations to other objects, sometimes join queries are issued on-demand in the specific getter (lazy loading). So basically, we have implemented most of the ORM's functionality manually. The reason for that was performance. We have very strong requirements for speed, and back in 2005 (when this code was written) performance tests has shown that none of mainstream ORMs were that fast as hand-written SQL. The problems we are facing now that make us think of ORM are: Most of the paths in this code are well-tested and are stable. However, some rarely-used code is prone to result set and connection leaks that are very hard to detect We are currently squeezing some additional performance by adding caching to our persistence layer and it's a huge pain to maintain the cached objects manually in this setup Support of this code when DB schema changes is a big problem. I am looking for an advice on what could be the best alternative for us. As far as I know, ORMs has advanced in last 5 years, so it might be that now there's one that offers an acceptable performance. As I see this issue, we need to address those points: Find some way to reuse at least some of the written SQL to express mappings Have the possibility to issue native SQL queries without the necessity to manually decompose their results (i.e. avoid manual rs.getInt(42) as they are very sensitive to schema changes) Add a non-intrusive caching layer Keep the performance figures. Is there any ORM framework you could recommend with regards to that?

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• Improving performance on data pasting 2000 rows with validations

  - by Lohit

  I have N rows (which could be nothing less than 1000) on an excel spreadsheet. And in this sheet our project has 150 columns like this: Now, our application needs data to be copied (using normal Ctrl+C) and pasted (using Ctrl+V) from the excel file sheet on our GUI sheet. Copy pasting 1000 records takes around 5-6 seconds which is okay for our requirement, but the problem is when we need to make sure the data entered is valid. So we have to validate data in each row generate appropriate error messages and format the data as per requirement. So we need to at runtime parse and evaluate data in each row. Now all the formatting of data and validations come from the back-end database and we have it in a data-table (dtValidateAndFormatConditions). The conditions would be around 50. So you can see how slow this whole process becomes since N X 150 X 50 operations are required to complete this whole process. Initially it took approximately 2-3 minutes but now i have reduced it to 20 - 30 seconds. However i have increased the speed by making an expression parser of my own - and not by any algorithm, is there any other way i can improve performance, by using Divide and Conquer or some other mechanism. Currently i am not really sure how to go about this. Here is what part of my code looks like: public virtual void ValidateAndFormatOnCopyPaste(DataTable DtCopied, int CurRow) { foreach (DataRow dRow in dtValidateAndFormatConditions.Rows) { string Condition = dRow["Condition"]; string FormatValue = Value = dRow["Value"]; GetValidatedFormattedData(DtCopied,ref Condition, ref FormatValue ,iRowIndex); Condition = Parse(Condition); dRow["Condition"] = Condition; FormatValue = Parse(FormatValue ); dRow["Value"] = FormatValue; } } The above code gets called row-wise like this: public override void ValidateAndFormat(DataTable dtChangedRecords, CellRange cr) { int iRowStart = cr.Row, iRowEnd = cr.Row + cr.RowCount; for (int iRow = iRowStart; iRow < iRowEnd; iRow++) { ValidateAndFormatOnCopyPaste(dtChangedRecords,iRow); } } Please know my question needs a more algorithmic solution than code optimization, however any answers containing code related optimizations will be appreciated as well. (Tagged Linq because although not seen i have been using linq in some parts of my code).

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• mySQL to .XSL help

  - by kielie

  hi guys, I have to create a script that takes a mySQL table, and exports it into .XSL format, and then saves that file into a specified folder on the web host. I got it working, but now I can't seem to get it to automatically save the file to the location without prompting the user. It needs to run every day at a specified time, so it can save the previous days leads into a .XSL file on the web host. Here is the code: <?php // DB TABLE Exporter // // How to use: // // Place this file in a safe place, edit the info just below here // browse to the file, enjoy! // CHANGE THIS STUFF FOR WHAT YOU NEED TO DO $dbhost = "-"; $dbuser = "-"; $dbpass = "-"; $dbname = "-"; $dbtable = "-"; // END CHANGING STUFF $cdate = date("Y-m-d"); // get current date // first thing that we are going to do is make some functions for writing out // and excel file. These functions do some hex writing and to be honest I got // them from some where else but hey it works so I am not going to question it // just reuse // This one makes the beginning of the xls file function xlsBOF() { echo pack("ssssss", 0x809, 0x8, 0x0, 0x10, 0x0, 0x0); return; } // This one makes the end of the xls file function xlsEOF() { echo pack("ss", 0x0A, 0x00); return; } // this will write text in the cell you specify function xlsWriteLabel($Row, $Col, $Value ) { $L = strlen($Value); echo pack("ssssss", 0x204, 8 + $L, $Row, $Col, 0x0, $L); echo $Value; return; } // make the connection an DB query $dbc = mysql_connect( $dbhost , $dbuser , $dbpass ) or die( mysql_error() ); mysql_select_db( $dbname ); $q = "SELECT * FROM ".$dbtable." WHERE date ='$cdate'"; $qr = mysql_query( $q ) or die( mysql_error() ); // Ok now we are going to send some headers so that this // thing that we are going make comes out of browser // as an xls file. // header("Pragma: public"); header("Expires: 0"); header("Cache-Control: must-revalidate, post-check=0, pre-check=0"); header("Content-Type: application/force-download"); header("Content-Type: application/octet-stream"); header("Content-Type: application/download"); //this line is important its makes the file name header("Content-Disposition: attachment;filename=export_".$dbtable.".xls "); header("Content-Transfer-Encoding: binary "); // start the file xlsBOF(); // these will be used for keeping things in order. $col = 0; $row = 0; // This tells us that we are on the first row $first = true; while( $qrow = mysql_fetch_assoc( $qr ) ) { // Ok we are on the first row // lets make some headers of sorts if( $first ) { foreach( $qrow as $k => $v ) { // take the key and make label // make it uppper case and replace _ with ' ' xlsWriteLabel( $row, $col, strtoupper( ereg_replace( "_" , " " , $k ) ) ); $col++; } // prepare for the first real data row $col = 0; $row++; $first = false; } // go through the data foreach( $qrow as $k => $v ) { // write it out xlsWriteLabel( $row, $col, $v ); $col++; } // reset col and goto next row $col = 0; $row++; } xlsEOF(); exit(); ?> I tried using, fwrite to accomplish this, but it didn't seem to go very well, I removed the header information too, but nothing worked. Here is the original code, as I found it, any help would be greatly appreciated. :-) Thanx in advance. :-)

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• ASP.Net/C# File Upload Progress Display

  - by Ioxp

  I am having a hard time figuring out how to do a "Please wait while file is uploading" message when the user submits the following form. So far the application works to specification with regards to checking files and uploading to the server. You will see some java script below, this is there to allow me to fake out the style of the file up load buttons so that it matches the rest of the site. I have tried to use the ASP.Net Ajax controls to do this however the updateprogress panel would not show up. In further reading it was explained that this has something to do with the Asynchronous transfer that the file upload control uses when you issue a PostedFile.SaveAs("filename") command. I also found a site that refereed to using an iframe to do the job. I'm not really sure if that's the best way to go about doing this or not so I'm asking you the professionals of stackoverflow for help to try and resolve this issue. I will be more than happy to post any spinets you need from my code to help me expedite a solution for this. <table border="0"> <tr> <td>File 1:&nbsp;</td> <td><div class="fileinputs"><input type="file" class="file" size="37" id="f1" runat="server" /></div></td> </tr> <tr> <td>File 2:&nbsp;</td> <td><div class="fileinputs"><input type="file" class="file" size="37" id="f2" runat="server" /></div></td> </tr> <tr> <td colspan="2" style="text-align:right;"><asp:ImageButton ID="ImageButton1" runat="server" ImageUrl="~/Images/Buttons/Upload_Files.gif" OnClick="Submit_Form" /></td> </tr> </table> <asp:Label ID="lblError" runat="server" Text=""></asp:Label> <script type="text/javascript"> var fakeFileUpload = document.createElement('div'); fakeFileUpload.className = 'fakefile'; var fakeInput = document.createElement('input'); fakeInput.style.width = '200px'; fakeFileUpload.appendChild(fakeInput); var image = document.createElement('img'); image.src='../Images/Buttons/Browse.gif'; fakeFileUpload.appendChild(image); var x = document.getElementsByTagName('input'); for (var i=0;i<x.length;i++) { if (x[i].type != 'file') continue; if (x[i].parentNode.className != 'fileinputs') continue; x[i].className = 'file hidden'; var clone = fakeFileUpload.cloneNode(true); x[i].parentNode.appendChild(clone); x[i].relatedElement = clone.getElementsByTagName('input')[0]; x[i].onchange = x[i].onmouseout = function () { this.relatedElement.value = this.value; } } </script>

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• how to gzip-compress large Ajax responses (HTML only) in Coldfusion?

  - by frequent

  I'm running Coldfusion8 and jquery/jquery-mobile on the front-end. I'm playing around with an Ajax powered search engine trying to find the best tradeoff between data-volume and client-side processing time. Currently my AJAX search returns 40k of (JQM-enhanced markup), which avoids any client-side enhancement. This way I'm getting by without the page stalling for about 2-3 seconds, while JQM enhances all elements in the search results. What I'm curious is whether I can gzip Ajax responses sent from Coldfusion. If I check the header of my search right now, I'm having this: RESPONSE-header Connection Keep-Alive Content-Type text/html; charset=UTF-8 Date Sat, 01 Sep 2012 08:47:07 GMT Keep-Alive timeout=5, max=95 Server Apache/2.2.21 (Win32) mod_ssl/2.2.21 ... Transfer-Encoding chunked REQUEST-header Accept */* Accept-Encoding gzip, deflate Accept-Language de-de,de;q=0.8,en-us;q=0.5,en;q=0.3 Connection keep-alive Cookie CFID= ; CFTOKEN= ; resolution=1143 Host www.host.com Referer http://www.host.com/dev/users/index.cfm So, my request would accept gzip, deflate, but I'm getting back chunked. I'm generating the AJAX response in a cfsavecontent (called compressedHTML) and run this to eliminate whitespace <cfrscipt> compressedHTML = reReplace(renderedResults, "\>\s+\<", "> <", "ALL"); compressedHTML = reReplace(compressedHTML, "\s{2,}", chr(13), "ALL"); compressedHTML = reReplace(compressedHTML, "\s{2,}", chr(09), "ALL"); </cfscript> before sending the compressedHTML in a response object like this: {"SUCCESS":true,"DATA": compressedHTML } Question If I know I'm sending back HTML in my data object via Ajax, is there a way to gzip the response server-side before returning it vs sending chunked? If this is at all possible? If so, can I do this inside my response object or would I have to send back "pure" HTML? Thanks! EDIT: Found this on setting a 'web.config' for dynamic compression - doesn't seem to work EDIT2: Found thi snippet and am playing with it, although I'm not sure this will work. <cfscript> compressedHTML = reReplace(renderedResults, "\>\s+\<", "> <", "ALL"); compressedHTML = reReplace(compressedHTML, "\s{2,}", chr(13), "ALL"); compressedHTML = reReplace(compressedHTML, "\s{2,}", chr(09), "ALL"); if ( cgi.HTTP_ACCEPT_ENCODING contains "gzip" AND not showRaw ){ cfheader name="Content-Encoding" value="gzip"; bos = createObject("java","java.io.ByteArrayOutputStream").init(); gzipStream = createObject("java","java.util.zip.GZIPOutputStream"); gzipStream.init(bos); gzipStream.write(compressedHTML.getBytes("utf-8")); gzipStream.close(); bos.flush(); bos.close(); encoder = createObject("java","sun.misc. outStr= encoder.encode(bos.toByteArray()); compressedHTML = toString(bos.toByteArray()); } </cfscript> Probably need to try this on the response object and not the compressedTHML variable

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• which way is correct to retrive data from oracle??

  - by rima

  before answer me plz thinking about the futures of these kind of program and answer me plz. I wanna get some data from oracle server like: 1-get all the function,package,procedure and etc for showing them or drop them & etc... 2-compile my *.sql files,get the result if they have problem & etc... becuz I was beginner in oracle first of all I for solve the second problem I try to connect to sqlPlus by RUN sqlplus and trace the output(I mean,I change the output stream of shell and trace what happend and handle the assigned message to customer. NOW THIS PART SUCCEED. just a little bit I have problem with get all result because the output is asynchronous.any way... [in this case I log in to oracle Server by send argument to the sqlplus by make a process in c#] after that I try to get all function,package or procedure name,but I have problem in speed!so I try to use oracle.DataAccess.dll to connect the database. now I m so confusing about: which way is correct way to build a program that work like Oracle Developer! I do not have any experience for like these program how work. If Your answer is I must use the second way follow this part plz: I search a little bit the Golden,PLedit (Benthic software),I have little bit problem how I must create the connection string?because I thinking about how I can find the host name or port number that oracle work on them?? am I need read the TNSNames.Ora file? IF your answer is I must use the first way follow this part plz: do u have any Idea for how I parse the output?because for example the result of a table is so confusing...[i can handle & program it but I really need someone experience,because the important things to me learn how such software work so nice and with quick response?] All of the has different style in output... If you are not sure Can u help me which book can help me in this way i become expert? becuz for example all the C# write just about how u can connect to DB and the DB books write how u can use this DB program,I looking for a book that give me some Idea how develop an interface for do transaction between these two.not simple send and receive data,for example how write a compiler for them. the language of book is not different for me i know C#,java,VB,sql,Oracle Thanks.

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• Just a small problem regarding javscript BOM question

  - by caramel1991

  The question is this: Create a page with a number of links. Then write code that fires on the window onload event, displaying the href of each of the links on the page. And this is my solution <html> <body language="Javascript" onload="displayLink()"> <a href="http://www.google.com/">First link</a> <a href="http://www.yahoo.com/">Second link</a> <a href="http://www.msn.com/">Third link</a> <script type="text/javascript" language="Javascript"> function displayLink() { for(var i = 0;document.links[i];i++) { alert(document.links[i].href); } } </script> </body> </html> This is the answer provided by the book <html> <head> <script language=”JavaScript” type=”text/javascript”> function displayLinks() { var linksCounter; for (linksCounter = 0; linksCounter < document.links.length; linksCounter++) { alert(document.links[linksCounter].href); } } </script> </head> <body onload=”displayLinks()”> <A href=”link0.htm” >Link 0</A> <A href=”link1.htm”>Link 2</A> <A href=”link2.htm”>Link 2</A> </body> </html> Before I get into the javascript tutorial on how to check user browser version or model,I was using the same method as the example,by acessing the length property of the links array for the loop,but after I read through the tutorial,I find out that I can also use this alternative ways,by using the method that the test condition will evalute to true only if the document.links[i] return a valid value,so does my code is written using the valid method??If it's not,any comment regarding how to write a better code??Correct me if I'm wrong,I heard some of the people say "a good code is not evaluate solely on whether it works or not,but in terms of speed,the ability to comprehend the code,and could posssibly let others to understand the code easily".Is is true??

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• Custom Online Backup Solution Advice

  - by Martín Marconcini

  I have to implement a way so our customers can backup their SQL 2000/5/8 databasase online. The application they use is a C#/.NET35 Winforms application that connects to a SQL Server (can be 2000/2005/2008, sometimes express editions). The SQL Server is on the same LAN. Our application has a very specific UI and we must code each form following those guidelines. There’s lots of GDI+ to give it the look and feel we want. For that reason, using a 3rd party application is not a very good idea. We need to charge the customer on a monthly/annual basis for the service. Preferably, the customer doesn’t need to care about bandwidth and storage space. It must be transparent. Given the above reqs., my first thoughts are: Solution 1: Code some sort of FTP basic functionality with behind the scenes SQL Backup mechanism, then hire a Hosting service and compress-transfer the .BAK to the Hosting. Maintain a series of Folders (for each customer). They won’t see what’s happening. They will just see a list of their files and a big “Backup now” button that will perform the SQL backup, compress it and upload it (and update the file list) ;) Pros: Not very complicated to implement, simple to use, fairly simple to configure (could have a dedicated ftp user/pass) Cons: Finding a “ftp” only hosting plan is not probably going to be easy, they usually come with a bunch of stuff. FTP is not always the best protocol. more? Solution 2: Similar to 1, but instead of FTP, find a cloud computing service like Amazon S3, Mosso or similar. Pros: Cloud Storage is fast, reliable, etc. It’s kind of easy to implement (specially if there are APIs like AWS or Mosso). Cons: I have been unable to come up with a service optimized for resellers where I can give multiple sub-accounts (one for each customer). Billing is going to be a nightmare cuz these services bill per/GB and with One account it’s impossible to differentiate each customer. Solution 3: Similar to 2, but letting the user create their own account on Amazon S3 (for example). Pros: You forget about billing and such. Cons: A mess for the customer who has to open the Amazon (or whatever) account, will be charged for that and not from you. You can’t really charge the customer (since you’re just not doing anything). Solution 4: Use one of the many backup online solutions that use the tech in cloud storage. Pros: many of these include SQL Server backup, and a lot of features that we’d have to implement. Plus web access and stuff like that will come included. Cons: Still have the billing problem described in number 2. Little of these companies (if any) offers “reseller” accounts. You have to eventually use their software (some offer certain branding). Any better approach? Summary: You have a software (.NET Winapp). You want your users to be able to backup their SQL Server databases online (and be able to retrieve the backups if needed). You ideally would like to charge the customer for this service (i.e. XX € a year).

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• java web application best practices

  - by Bruce

  Hi all I'm trying to figure out the optimum way to develop and release a fairly simple web application, and I'm running into several problems. I'll outline the decisions I've made, because somewhere I've clearly gone off the rails.. Hugely grateful for any help! I have what I think is a fairly simple web application. It contains a couple of jsps that reference a couple of java beans, and the usual static html, js, css and images. Decision 1) I wanted to have a clear and clean release procedure, such that I could develop on my local machine and then release reliably to a production machine. I therefore made the decision to package the application into a war file (including all the static resources), to minimize the separate bits and pieces I would need to release. So far so good? Decision 2) I wanted things on my local machine to be as similar as possible to the production environment. So in my html, for example, I may have a reference to a static file such as http://static.foo.com/file . To keep this code working seamlessly on dev and prod, I decided to put static.foo.com in my /etc/hosts when developing locally, so that all the urls work correctly without changing anything. Decision 3) I decided to use eclipse and maven to give me a best practice environment for administering and building my project. So I have a nice tight set up now, except that: Every time I want to change anything in development, like one line in an html file, I have to rebuild the entire project and then wait for tomcat to load the war before I can see if it's what I wanted. So my questions are: 1) Is there a way to connect up eclipse and tomcat so that I don't have to rebuild the war each time? ie tomcat is looking straight at my actual workspace to serve up the static files? 2)I think I'm maybe making things harder by using /etc/hosts to reflect production urls - is there a better way that doesn't involve manually changing over urls (relative urls are fine of course, but where you have many subdomains, say one for static files and one for dynamic, you have to write out the full path, surely?) 3) Is this really best practice?? How do people set things up so that they balance the requirement for an automated, all-encompassing build process on the one hand, and the speed and flexibility to be able to develop javascript and html and css quickly, as quickly as if one just pointed apache at the directory and developed live? What do people find works? Many thanks!

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• Modify audio pitch of recorded clip (m4v)

  - by devcube

  I'm writing an app in which I'm trying to change the pitch of the audio when I'm recording a movie (.m4v). Or by modifying the audio pitch of the movie afterwards. I want the end result to be a movie (.m4v) that has the original length (i.e. same visual as original) but with modified sound pitch, e.g. a "chipmunk voice". A realtime conversion is to prefer if possible. I've read alot about changing audio pitch in iOS but most examples focus on playback, i.e. playing the sound with a different pitch. In my app I'm recording a movie (.m4v / AVFileTypeQuickTimeMovie) and saving it using standard AVAssetWriter. When saving the movie I have access to the following elements where I've tried to manipulate the audio (e.g. modify the pitch): audio buffer (CMSampleBufferRef) audio input writer (AVAssetWriterAudioInput) audio input writer options (e.g. AVNumberOfChannelsKey, AVSampleRateKey, AVChannelLayoutKey) asset writer (AVAssetWriter) I've tried to hook into the above objects to modify the audio pitch, but without success. I've also tried with Dirac as described here: Real Time Pitch Change In iPhone Using Dirac And OpenAL with AL_PITCH as described here: Piping output from OpenAL into a buffer And the "BASS" library from un4seen: Change Pitch/Tempo In Realtime I haven't found success with any of the above libs, most likely because I don't really know how to use them, and where to hook them into the audio saving code. There seems to be alot of librarys that have similar effects but focuses on playback or custom recording code. I want to manipulate the audio stream I've already got (AVAssetWriterAudioInput) or modify the saved movie clip (.m4v). I want the video to be unmodifed visually, i.e. played at the same speed. But I want the audio to go faster (like a chipmunk) or slower (like a ... monster? :)). Do you have any suggestions how I can modify the pitch in either real time (when recording the movie) or afterwards by converting the entire movie (.m4v file)? Should I look further into Dirac, OpenAL, SoundTouch, BASS or some other library? I want to be able to share the movie to others with modified audio, that's the reason I can't rely on modifying the pitch for playback only. Any help is appreciated, thanks!

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• XML pass values to timer, AS3

  - by VideoDnd

  My timer has three variables that I can trace to the output window, but don't know how to pass them to the timer. How to I pass the XML values to my timer? Purpose I want to test with an XML document, before I try connecting it to an XML socket. myXML <?xml version="1.0" encoding="utf-8"?> <SESSION> <TIMER TITLE="speed">100</TIMER> <COUNT TITLE="starting position">-77777</COUNT> <FCOUNT TITLE="ramp">1000</FCOUNT> </SESSION> myFlash //myTimer 'instance of mytext on stage' /* fields I want to change with XML */ //CHANGE TO 100 var timer:Timer = new Timer(10); //CHANGE TO -77777 var count:int = 0; //CHANGE TO 1000 var fcount:int = 0; timer.addEventListener(TimerEvent.TIMER, incrementCounter); timer.start(); function incrementCounter(event:TimerEvent) { count++; fcount=int(count*count/1000);//starts out slow... then speeds up mytext.text = formatCount(fcount); } function formatCount(i:int):String { var fraction:int = i % 100; var whole:int = i / 100; return ("0000000" + whole).substr(-7, 7) + "." + (fraction < 10 ? "0" + fraction : fraction); } //LOAD XML var myXML:XML; var myLoader:URLLoader = new URLLoader(); myLoader.load(new URLRequest("time.xml")); myLoader.addEventListener(Event.COMPLETE, processXML); //PARSE XML function processXML(e:Event):void { myXML = new XML(e.target.data); trace(myXML.ROGUE.*); trace(myXML); //TEXT var text:TextField = new TextField(); text.text = myXML.TIMER.*; text.textColor = 0xFF0000; addChild(text); } RESOURCES OReilly's ActionScript 3.0 Cookbook, Chapter 12 Strings, Chapter 20 XML

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• Writing a managed wrapper for unmanaged (C++) code - custom types/structs

  - by Bobby

  faacEncConfigurationPtr FAACAPI faacEncGetCurrentConfiguration( faacEncHandle hEncoder); I'm trying to come up with a simple wrapper for this C++ library; I've never done more than very simple p/invoke interop before - like one function call with primitive arguments. So, given the above C++ function, for example, what should I do to deal with the return type, and parameter? FAACAPI is defined as: #define FAACAPI __stdcall faacEncConfigurationPtr is defined: typedef struct faacEncConfiguration { int version; char *name; char *copyright; unsigned int mpegVersion; unsigned long bitRate; unsigned int inputFormat; int shortctl; psymodellist_t *psymodellist; int channel_map[64]; } faacEncConfiguration, *faacEncConfigurationPtr; AFAIK this means that the return type of the function is a reference to this struct? And faacEncHandle is: typedef struct { unsigned int numChannels; unsigned long sampleRate; ... SR_INFO *srInfo; double *sampleBuff[MAX_CHANNELS]; ... double *freqBuff[MAX_CHANNELS]; double *overlapBuff[MAX_CHANNELS]; double *msSpectrum[MAX_CHANNELS]; CoderInfo coderInfo[MAX_CHANNELS]; ChannelInfo channelInfo[MAX_CHANNELS]; PsyInfo psyInfo[MAX_CHANNELS]; GlobalPsyInfo gpsyInfo; faacEncConfiguration config; psymodel_t *psymodel; /* quantizer specific config */ AACQuantCfg aacquantCfg; /* FFT Tables */ FFT_Tables fft_tables; int bitDiff; } faacEncStruct, *faacEncHandle; So within that struct we see a lot of other types... hmm. Essentially, I'm trying to figure out how to deal with these types in my managed wrapper? Do I need to create versions of these types/structs, in C#? Something like this: [StructLayout(LayoutKind.Sequential)] struct faacEncConfiguration { uint useTns; ulong bitRate; ... } If so then can the runtime automatically "map" these objects onto eachother? And, would I have to create these "mapped" types for all the types in these return types/parameter type hierarchies, all the way down until I get to all primitives? I know this is a broad topic, any advice on getting up-to-speed quickly on what I need to learn to make this happen would be very much appreciated! Thanks!

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• Mysql select - improve performances

  - by realshadow

  Hey, I am working on an e-shop which sells products only via loans. I display 10 products per page in any category, each product has 3 different price tags - 3 different loan types. Everything went pretty well during testing time, query execution time was perfect, but today when transfered the changes to the production server, the site "collapsed" in about 2 minutes. The query that is used to select loan types sometimes hangs for ~10 seconds and it happens frequently and thus it cant keep up and its hella slow. The table that is used to store the data has approximately 2 milion records and each select looks like this: SELECT * FROM products_loans WHERE KOD IN("X17/Q30-10", "X17/12", "X17/5-24") AND 369.27 BETWEEN CENA_OD AND CENA_DO; 3 loan types and the price that needs to be in range between CENA_OD and CENA_DO, thus 3 rows are returned. But since I need to display 10 products per page, I need to run it trough a modified select using OR, since I didnt find any other solution to this. I have asked about it here, but got no answer. As mentioned in the referencing post, this has to be done separately since there is no column that could be used in a join (except of course price and code, but that ended very, very badly). Here is the show create table, kod and CENA_OD/CENA_DO very indexed via INDEX. CREATE TABLE `products_loans` ( `KOEF_ID` bigint(20) NOT NULL, `KOD` varchar(30) NOT NULL, `AKONTACIA` int(11) NOT NULL, `POCET_SPLATOK` int(11) NOT NULL, `koeficient` decimal(10,2) NOT NULL default '0.00', `CENA_OD` decimal(10,2) default NULL, `CENA_DO` decimal(10,2) default NULL, `PREDAJNA_CENA` decimal(10,2) default NULL, `AKONTACIA_SUMA` decimal(10,2) default NULL, `TYP_VYHODY` varchar(4) default NULL, `stage` smallint(6) NOT NULL default '1', PRIMARY KEY (`KOEF_ID`), KEY `CENA_OD` (`CENA_OD`), KEY `CENA_DO` (`CENA_DO`), KEY `KOD` (`KOD`), KEY `stage` (`stage`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 And also selecting all loan types and later filtering them trough php doesnt work good, since each type has over 50k records and the select takes too much time as well... Any ides about improving the speed are appreciated. Edit: Here is the explain +----+-------------+----------------+-------+---------------------+------+---------+------+--------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+----------------+-------+---------------------+------+---------+------+--------+-------------+ | 1 | SIMPLE | products_loans | range | CENA_OD,CENA_DO,KOD | KOD | 92 | NULL | 190158 | Using where | +----+-------------+----------------+-------+---------------------+------+---------+------+--------+-------------+ I have tried the combined index and it improved the performance on the test server from 0.44 sec to 0.06 sec, I cant access the production server from home though, so I will have to try it tomorrow.

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• Stored procedure performance randomly plummets; trivial ALTER fixes it. Why?

  - by gWiz

  I have a couple of stored procedures on SQL Server 2005 that I've noticed will suddenly take a significantly long time to complete when invoked from my ASP.NET MVC app running in an IIS6 web farm of four servers. Normal, expected completion time is less than a second; unexpected anomalous completion time is 25-45 seconds. The problem doesn't seem to ever correct itself. However, if I ALTER the stored procedure (even if I don't change anything in the procedure, except to perhaps add a space to the script created by SSMS Modify command), the completion time reverts to expected completion time. IIS and SQL Server are running on separate boxes, both running Windows Server 2003 R2 Enterprise Edition. SQL Server is Standard Edition. All machines have dual Xeon E5450 3GHz CPUs and 4GB RAM. SQL Server is accessed using its TCP/IP protocol over gigabit ethernet (not sure what physical medium). The problem is present from all web servers in the web farm. When I invoke the procedure from a query window in SSMS on my development machine, the procedure completes in normal time. This is strange because I was under the impression that SSMS used the same SqlClient driver as in .NET. When I point my development instance of the web app to the production database, I again get the anomalous long completion time. If my SqlCommand Timeout is too short, I get System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Question: Why would performing ALTER on the stored procedure, without actually changing anything in it, restore the completion time to less than a second, as expected? Edit: To clarify, when the procedure is running slow for the app, it simultaneously runs fine in SSMS with the same parameters. The only difference I can discern is login credentials (next time I notice the behavior, I'll be checking from SSMS with the same creds). The ultimate goal is to get the procs to sustainably run with expected speed without requiring occasional intervention. Resolution: I wanted to to update this question in case others are experiencing this issue. Following the leads of the answers below, I was able to consistently reproduce this behavior. In order to test, I utilize sp_recompile and pass it one of the susceptible sprocs. I then initiate a website request from my browser that will invoke the sproc with atypical parameters. Lastly, I initiate a website request to a page that invokes the sproc with typical parameters, and observe that the request does not complete because of a SQL timeout on the sproc invocation. To resolve this on SQL Server 2005, I've added OPTIMIZE FOR hints to my SELECT. The sprocs that were vulnerable all have the "all-in-one" pattern described in this article. This pattern is certainly not ideal but was a necessary trade-off given the timeframe for the project.

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• Primary language - C++/Qt, C#, Java?

  - by Airjoe

  I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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• Having trouble doing an Update with a Linq to Sql object

  - by Pure.Krome

  Hi folks, i've got a simple linq to sql object. I grab it from the database and change a field then save. No rows have been updated. :( When I check the full Sql code that is sent over the wire, I notice that it does an update to the row, not via the primary key but on all the fields via the where clause. Is this normal? I would have thought that it would be easy to update the field(s) with the where clause linking on the Primary Key, instead of where'ing (is that a word :P) on each field. here's the code... using (MyDatabase db = new MyDatabase()) { var boardPost = (from bp in db.BoardPosts where bp.BoardPostId == boardPostId select bp).SingleOrDefault(); if (boardPost != null && boardPost.BoardPostId > 0) { boardPost.ListId = listId; // This changes the value from 0 to 'x' db.SubmitChanges(); } } and here's some sample sql.. exec sp_executesql N'UPDATE [dbo].[BoardPost] SET [ListId] = @p6 WHERE ([BoardPostId] = @p0) AND .... <snip the other fields>',N'@p0 int,@p1 int,@p2 nvarchar(9),@p3 nvarchar(10),@p4 int,@p5 datetime,@p6 int',@p0=1276,@p1=212787,@p2=N'ttreterte',@p3=N'ttreterte3',@p4=1,@p5='2009-09-25 12:32:12.7200000',@p6=72 Now, i know there's a datetime field in this update .. and when i checked the DB it's value was/is '2009-09-25 12:32:12.720' (less zero's, than above) .. so i'm not sure if that is messing up the where clause condition... but still! should it do a where clause on the PK's .. if anything .. for speed! Yes / no ? UPDATE After reading nitzmahone's reply, I then tried playing around with the optimistic concurrency on some values, and it still didn't work :( So then I started some new stuff ... with the optimistic concurrency happening, it includes a where clause on the field it's trying to update. When that happens, it doesn't work. so.. in the above sql, the where clause looks like this ... WHERE ([BoardPostId] = @p0) AND ([ListId] IS NULL) AND ... <rest snipped>) This doesn't sound right! the value in the DB is null, before i do the update. but when i add the ListId value to the where clause (or more to the point, when L2S add's it because of the optomistic concurrecy), it fails to find/match the row. wtf?

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• help me to choose the best soulotion for my purpose to build my software.

  - by rima

  before answer me plz thinking about the futures of these kind of program and answer me plz. I wanna get some data from oracle server like: 1-get all the function,package,procedure and etc for showing them or drop them & etc... 2-compile my *.sql files,get the result if they have problem & etc... becuz I was beginner in oracle first of all I for solve the second problem I try to connect to sqlPlus by RUN sqlplus and trace the output(I mean,I change the output stream of shell and trace what happend and handle the assigned message to customer. NOW THIS PART SUCCEED. just a little bit I have problem with get all result because the output is asynchronous.any way... [in this case I log in to oracle Server by send argument to the sqlplus by make a process in c#] after that I try to get all function,package or procedure name,but I have problem in speed!so I try to use oracle.DataAccess.dll to connect the database. now I m so confusing about: which way is correct way to build a program that work like Oracle Developer! I do not have any experience for like these program how work. If Your answer is I must use the second way follow this part plz: I search a little bit the Golden,PLedit (Benthic software),I have little bit problem how I must create the connection string?because I thinking about how I can find the host name or port number that oracle work on them?? am I need read the TNSNames.Ora file? IF your answer is I must use the first way follow this part plz: do u have any Idea for how I parse the output?because for example the result of a table is so confusing...[i can handle & program it but I really need someone experience,because the important things to me learn how such software work so nice and with quick response?] All of the has different style in output... If you are not sure Can u help me which book can help me in this way i become expert? becuz for example all the C# write just about how u can connect to DB and the DB books write how u can use this DB program,I looking for a book that give me some Idea how develop an interface for do transaction between these two.not simple send and receive data,for example how write a compiler for them. the language of book is not different for me i know C#,java,VB,sql,Oracle Thanks.

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• How to design service that can provide interface as JAX-WS web service, or via JMS, or as local meth

  - by kevinegham

  Using a typical JEE framework, how do I develop and deploy a service that can be called as a web service (with a WSDL interface), be invoked via JMS messages, or called directly from another service in the same container? Here's some more context: Currently I am responsible for a service (let's call it Service X) with the following properties: Interface definition is a human readable document kept up-to-date manually. Accepts HTTP form-encoded requests to a single URL. Sends plain old XML responses (no schema). Uses Apache to accept requests + a proprietary application server (not servlet or EJB based) containing all logic which runs in a seperate tier. Makes heavy use of a relational database. Called both by internal applications written in a variety of languages and also by a small number of third-parties. I want to (or at least, have been told to!): Switch to a well-known (pref. open source) JEE stack such as JBoss, Glassfish, etc. Split Service X into Service A and Service B so that we can take Service B down for maintenance without affecting Service A. Note that Service B will depend on (i.e. need to make requests to) Service A. Make both services easier for third parties to integrate with by providing at least a WS-I style interface (WSDL + SOAP + XML + HTTP) and probably a JMS interface too. In future we might consider a more lightweight API too (REST + JSON? Google Protocol Buffers?) but that's a nice to have. Additional consideration are: On a smaller deployment, Service A and Service B will likely to running on the same machine and it would seem rather silly for them to use HTTP or a message bus to communicate; better if they could run in the same container and make method calls to each other. Backwards compatibility with the existing ad-hoc Service X interface is not required, and we're not planning on re-using too much of the existing code for the new services. I'm happy with either contract-first (WSDL I guess) or (annotated) code-first development. Apologies if my terminology is a bit hazy - I'm pretty experienced with Java and web programming in general, but am finding it quite hard to get up to speed with all this enterprise / SOA stuff - it seems I have a lot to learn! I'm also not very used to using a framework rather than simply writing code that calls some packages to do things. I've got as far as downloading Glassfish, knocking up a simple WSDL file and using wsimport + a little dummy code to turn that into a WAR file which I've deployed.

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• Spinning a circle in J2ME using a Canvas.

  - by JohnQPublic

  Hello all! I have a problem where I need to make a multi-colored wheel spin using a Canvas in J2ME. What I need to do is have the user increase the speed of the spin or slow the spin of the wheel. I have it mostly worked out (I think) but can't think of a way for the wheel to spin without causing my cellphone to crash. Here is what I have so far, it's close but not exactly what I need. class MyCanvas extends Canvas{ //wedgeOne/Two/Three define where this particular section of circle begins to be drawn from int wedgeOne; int wedgeTwo; int wedgeThree; int spinSpeed; MyCanvas(){ wedgeOne = 0; wedgeTwo = 120; wedgeThree = 240; spinSpeed = 0; } //Using the paint method to public void paint(Graphics g){ //Redraw the circle with the current wedge series. g.setColor(255,0,0); g.fillArc(getWidth()/2, getHeight()/2, 100, 100, wedgeOne, 120); g.setColor(0,255,0); g.fillArc(getWidth()/2, getHeight()/2, 100, 100, wedgeTwo, 120); g.setColor(0,0,255); g.fillArc(getWidth()/2, getHeight()/2, 100, 100, wedgeThree, 120); } protected void keyPressed(int keyCode){ switch (keyCode){ //When the 6 button is pressed, the wheel spins forward 5 degrees. case KEY_NUM6: wedgeOne += 5; wedgeTwo += 5; wedgeThree += 5; repaint(); break; //When the 4 button is pressed, the wheel spins backwards 5 degrees. case KEY_NUM4: wedgeOne -= 5; wedgeTwo -= 5; wedgeThree -= 5; repaint(); } } I have tried using a redraw() method that adds the spinSpeed to each of the wedge values while(spinSpeed0) and calls the repaint() method after the addition, but it causes a crash and lockup (I assume due to an infinite loop). Does anyone have any tips or ideas how I could automate the spin so you do not have the press the button every time you want it to spin? (P.S - I have been lurking for a while, but this is my first post. If it's too general or asking for too much info (sorry if it is) and I either remove it or fix it. Thank you!)

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• How do I create a safe local development environment?

  - by docgnome

  I'm currently doing web development with another developer on a centralized development server. In the past this has worked alright, as we have two separate projects we are working on and rarely conflict. Now, however, we are adding a third (possible) developer into the mix. This is clearly going to create problems with other developers changes affecting my work and vice versa. To solve this problem, I'm thinking the best solution would be to create a virtual machine to distribute between the developers for local use. The problem I have is when it comes to the database. Given that we all develop on laptops, simply keeping a local copy of the live data is plain stupid. I've considered sanitizing the data, but I can't really figure out how to replace the real data, with data that would be representative of what people actually enter with out repeating the same information over and over again, e.g. everyone's address becomes 123 Testing Lane, Test Town, WA, 99999 or something. Is this really something to be concerned about? Are there tools to help with this sort of thing? I'm using MySQL. Ideally, if I sanitized the db it should be done from a script that I can run regularly. If I do this I'd also need a way to reduce the size of the db itself. (I figure I could select all the records created after x and whack them and all the records in corresponding tables out so that isn't really a big deal.) The second solution I've thought of is to encrypt the hard drive of the vm, but I'm unsure of how practical this is in terms of speed and also in the event of a lost/stolen laptop. If I do this, should the vm hard drive file itself be encrypted or should it be encrypted in the vm? (I'm assuming the latter as it would be portable and doesn't require the devs to have any sort of encryption capability on their OS of choice.) The third is to create a copy of the database for each developer on our development server that they are then responsible to keep the schema in sync with the canonical db by means of migration scripts or what have you. This solution seems to be the simplest but doesn't really scale as more developers are added. How do you deal with this problem?

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• CGAffineTransformMakeRotation goes the other way after 180 degrees (-3.14)

  - by TheKillerDev

  So, i am trying to do a very simple disc rotation (2d), according to the user touch on it, just like a DJ or something. It is working, but there is a problem, after certain amount of rotation, it starts going backwards, this amount is after 180 degrees or as i saw in while logging the angle, -3.14 (pi). I was wondering, how can i achieve a infinite loop, i mean, the user can keep rotating and rotating to any side, just sliding his finger? Also a second question is, is there any way to speed up the rotation? Here is my code right now: #import <UIKit/UIKit.h> @interface Draggable : UIImageView { CGPoint firstLoc; UILabel * fred; double angle; } @property (assign) CGPoint firstLoc; @property (retain) UILabel * fred; @end @implementation Draggable @synthesize fred, firstLoc; - (id)initWithFrame:(CGRect)frame { self = [super initWithFrame:frame]; angle = 0; if (self) { // Initialization code } return self; } -(void)handleObject:(NSSet *)touches withEvent:(UIEvent *)event isLast:(BOOL)lst { UITouch *touch =[[[event allTouches] allObjects] lastObject]; CGPoint curLoc = [touch locationInView:self]; float fromAngle = atan2( firstLoc.y-self.center.y, firstLoc.x-self.center.x ); float toAngle = atan2( curLoc.y-(self.center.y+10), curLoc.x-(self.center.x+10)); float newAngle = angle + (toAngle - fromAngle); NSLog(@"%f",newAngle); CGAffineTransform cgaRotate = CGAffineTransformMakeRotation(newAngle); self.transform = cgaRotate; if (lst) angle = newAngle; } -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch =[[[event allTouches] allObjects] lastObject]; firstLoc = [touch locationInView:self]; }; -(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { [self handleObject:touches withEvent:event isLast:NO]; }; -(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { [self handleObject:touches withEvent:event isLast:YES]; } @end And in the ViewController: UIImage *tmpImage = [UIImage imageNamed:@"theDisc.png"]; CGRect cellRectangle; cellRectangle = CGRectMake(-1,self.view.frame.size.height,tmpImage.size.width ,tmpImage.size.height ); dragger = [[Draggable alloc] initWithFrame:cellRectangle]; [dragger setImage:tmpImage]; [dragger setUserInteractionEnabled:YES]; dragger.layer.anchorPoint = CGPointMake(.5,.5); [self.view addSubview:dragger]; I am open to new/cleaner/more correct ways of doing this too. Thanks in advance.

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• Improving Javascript Load Times - Concatenation vs Many + Cache

  - by El Yobo

  I'm wondering which of the following is going to result in better performance for a page which loads a large amount of javascript (jQuery + jQuery UI + various other javascript files). I have gone through most of the YSlow and Google Page Speed stuff, but am left wondering about a particular detail. A key thing for me here is that the site I'm working on is not on the public net; it's a business to business platform where almost all users are repeat visitors (and therefore with caches of the data, which is something that YSlow assumes will not be the case for a large number of visitors). First up, the standard approach recommended by tools such as YSlow is to concatenate it, compress it, and serve it up in a single file loaded at the end of your page. This approach sounds reasonably effective, but I think that a key part of the reasoning here is to improve performance for users without cached data. The system I currently have is something like this * All javascript files are compressed and loaded at the bottom of the page * All javascript files have far future cache expiration dates, so will remain (for most users) in the cache for a long time * Pages only load the javascript files that they require, rather than loading one monolithic file, most of which will not be required Now, my understanding is that, if the cache expiration date for a javascript file has not been reached, then the cached version is used immediately; there is no HTTP request sent at to the server at all. If this is correct, I would assume that having multiple tags is not causing any performance penalty, as I'm still not having any additional requests on most pages (recalling from above that almost all users have populated caches). In addition to this, not loading the JS means that the browser doesn't have to interpret or execute all this additional code which it isn't going to need; as a B2B application, most of our users are unfortunately stuck with IE6 and its painfully slow JS engine. Another benefit is that, when code changes, only the affected files need to be fetched again, rather than the whole set (granted, it would only need to be fetched once, so this is not so much of a benefit). I'm also looking at using LabJS to allow for parallel loading of the JS when it's not cached. So, what do people think is a better approach? In a similar vein, what do you think about a similar approach to CSS - is monolithic better?

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• What are the pros and cons of using manual list iteration vs recursion through fail

  - by magus

  I come up against this all the time, and I'm never sure which way to attack it. Below are two methods for processing some season facts. What I'm trying to work out is whether to use method 1 or 2, and what are the pros and cons of each, especially large amounts of facts. methodone seems wasteful since the facts are available, why bother building a list of them (especially a large list). This must have memory implications too if the list is large enough ? And it doesn't take advantage of Prolog's natural backtracking feature. methodtwo takes advantage of backtracking to do the recursion for me, and I would guess would be much more memory efficient, but is it good programming practice generally to do this? It's arguably uglier to follow, and might there be any other side effects? One problem I can see is that each time fail is called, we lose the ability to pass anything back to the calling predicate, eg. if it was methodtwo(SeasonResults), since we continually fail the predicate on purpose. So methodtwo would need to assert facts to store state. Presumably(?) method 2 would be faster as it has no (large) list processing to do? I could imagine that if I had a list, then methodone would be the way to go.. or is that always true? Might it make sense in any conditions to assert the list to facts using methodone then process them using method two? Complete madness? But then again, I read that asserting facts is a very 'expensive' business, so list handling might be the way to go, even for large lists? Any thoughts? Or is it sometimes better to use one and not the other, depending on (what) situation? eg. for memory optimisation, use method 2, including asserting facts and, for speed use method 1? season(spring). season(summer). season(autumn). season(winter). % Season handling showseason(Season) :- atom_length(Season, LenSeason), write('Season Length is '), write(LenSeason), nl. % ------------------------------------------------------------- % Method 1 - Findall facts/iterate through the list and process each %-------------------------------------------------------------- % Iterate manually through a season list lenseason([]). lenseason([Season|MoreSeasons]) :- showseason(Season), lenseason(MoreSeasons). % Findall to build a list then iterate until all done methodone :- findall(Season, season(Season), AllSeasons), lenseason(AllSeasons), write('Done'). % ------------------------------------------------------------- % Method 2 - Use fail to force recursion %-------------------------------------------------------------- methodtwo :- % Get one season and show it season(Season), showseason(Season), % Force prolog to backtrack to find another season fail. % No more seasons, we have finished methodtwo :- write('Done').

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• Primary language - QtC++, C#, Java?

  - by Airjoe

  I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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