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• WPF Spellcheck Engine takes up too much memory.

  - by Matt H.

  Each datatemplate in my WPF ItemsControl contains FIVE custom bindable richtextbox controls. It is a data-driven app that for authoring multiple-choice questions -- The question and four answer choices must all support: 1) Spell check 2) Rich formatting (otherwise I'd use regular textboxes) The spell check object in .NET 4 has a Friend constructor that takes a single argument of owner As TextBoxBase This means every richtextbox in the ItemsControl has 5 Spellcheck objects! This is the problem -- every spell check engine is consuming about 500k memory. So after you favor in the spellcheck, bindings, additional controls in the DataTemplate, etc.. a single multi choice question consumes more than 3MB memory. Users with 100--200 questions will quickly see the App raise it's memory consumption to 500+ MB. Management is definitely not OK with this. Is there a way to minimimze this problem? The best suggestion I've heard is to enable/disable spellcheck if the richtextbox is in the ItemsControl's scrollviewer: I haven't gotten an answer to how to go about it: (http://stackoverflow.com/questions/2869012/possible-to-implement-an-isviewportvisible-dependencyproperty-for-an-item-in-an-i) Any good ideas?

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• Error building Visual Studio 2010 Silverlight 4 projects on Windows 7 with XP Mode

  - by Kevin Dente

  I installed Visual Studio 2010 Beta 2 in an XP Mode VM on Windows 7. Then I created a trivial Silverlight 4 (beta) project and tried to build it. I get the following error: Error 1 The "ValidateXaml" task failed unexpectedly. System.IO.FileLoadException: Could not load file or assembly 'file://\tsclient\d\Users\me\Documents\Visual Studio 2010\Projects\SilverlightApplication2\SilverlightApplication2\obj\Debug\SilverlightApplication2.dll' or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515) File name: 'file://\tsclient\d\Users\me\Documents\Visual Studio 2010\Projects\SilverlightApplication2\SilverlightApplication2\obj\Debug\SilverlightApplication2.dll' --- System.NotSupportedException: An attempt was made to load an assembly from a network location which would have caused the assembly to be sandboxed in previous versions of the .NET Framework. This release of the .NET Framework does not enable CAS policy by default, so this load may be dangerous. If this load is not intended to sandbox the assembly, please enable the loadFromRemoteSources switch. See http://go.microsoft.com/fwlink/?LinkId=155569 for more information. at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) at System.Reflection.RuntimeAssembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection, Boolean suppressSecurityChecks) at System.Reflection.RuntimeAssembly.InternalLoadFrom(String assemblyFile, Evidence securityEvidence, Byte[] hashValue, AssemblyHashAlgorithm hashAlgorithm, Boolean forIntrospection, Boolean suppressSecurityChecks, StackCrawlMark& stackMark) at System.Reflection.Assembly.LoadFrom(String assemblyFile) at Microsoft.Silverlight.Build.Tasks.ValidateXaml.XamlValidator.Execute(ITask task) at Microsoft.Silverlight.Build.Tasks.ValidateXaml.XamlValidator.Execute(ITask task) at Microsoft.Silverlight.Build.Tasks.ValidateXaml.Execute() at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute() at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask, Boolean& taskResult) I believe this is related to the fact that XP Mode redirects the My Documents folder to the host, turning it into a network share location, and some sort of CAS / security policy is being triggered. Anyone know how to fix it?

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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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• 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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• Architecting iPhone Views - seeking help on a specific issue + general advice

  - by Ev

  Hi there, I am a web developer (rails, python) that is new to iPhone development. I've done some desktop development in the past within the MS environment (C#). I'm trying to build a really simple iPhone application and I am confused by the way that views work in general. If someone can provide advice for my particular problem, along with some resources where I can learn how to architect iPhone views in the future, that would be awesome. I feel like a lot of the Apple documentation that I've come across is too specific - I am lacking a fundamental understanding of how views work on the iPhone. My particular problem looks like this: I need one view that displays some downloaded text content. This is the view that shows when the app loads, and it is pretty straightforward. Then I need a settings area (I've already decided I don't want to use the iPhone settings area). The settings area main page will have some text fields on it. It will also have a 2-row grouped table. Each cell in that table will take you to another view which also has a grouped table used for multi-select. I suspect that I can reuse the same view for these two final "detailed setting" views. In summary: home page settings main page detailed setting 1 detailed setting 2 Any help and advice appreciated.

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• Data in J2ME RecordStore does not persist across sessions

  - by Botond Balázs

  I'm building a mobile app with J2ME, and I've found that the data I write into a RecordStore can be accessed while the program is still running but it is lost after quitting and restarting it. No exception is thrown, the data is simply lost. UPDATE: Thanks everyone for your suggestions. I'm using NetBeans on Windows 7. I'm not sure if it is using the WTK version I have previously installed or another one it has installed somewhere else. I've checked my WTK folder for the files Pavel wrote about, but couldn't find them. Now I'm testing the features requiring persistence on my phone and everything else in the emulator, but it would of course be much better to be able to test everything in the emulator. private RecordStore recordStore = null; public MyMIDlet() { readStuff(); // output: nothing found in recordStore :( saveStuff(); readStuff(); // output: stuff } private void readStuff() { try { recordStore = RecordStore.openRecordStore(REC_STORE, true); int n = recordStore.getNumRecords(); String stuff; if (n == 0) { stuff = "nothing found in recordStore :("; } else { stuff = new String(recordStore.getRecord(1)); } System.out.println(stuff); } catch (Exception e) { System.out.println("Exception occured in readStuff: " + e.getMessage()); } finally { if (recordStore != null) { try { recordStore.closeRecordStore(); } catch (Exception e) { // ignore } } } } private void saveStuff() { try { recordStore = RecordStore.openRecordStore(REC_STORE, true); int n = recordStore.getNumRecords(); byte[] stuff = "stuff".getBytes(); recordStore.addRecord(stuff, 0, stuff.length); } catch (Exception e) { System.out.println("Exception occured in saveStuff: " + e.getMessage()); } finally { if (recordStore != null) { try { recordStore.closeRecordStore(); } catch (Exception e) { // ignore } } } }

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• Open Source CMS (.Net vs Java)

  - by CmsAndDotNetKindaGuy

  I must say up-front that this is not a strictly programming-related question and a very opinionated one. I am the lead developer of the dominant .Net CMS in my country and I don't like my own product :). Managerial decisions over what is important or not and large chunks of legacy code done before I joined gives me headache every day I go for work. Anyway, having a vast amount of experience in web industry and a very good grasp of C# and programming practices I'm designing my own CMS the past few months. Now the problem is that I'm an open source kinda guy so I have a dilemma. Should I use C# and .Net which has crippled multi-platform support or should I drop .Net entirely and start learning Java where I can create a truly open-source and cross-platform CMS? Please don't answer that I should contribute to an existing open source CMS. I ruled that out after spending a great deal of time searching for something similar in structure to what I have in mind. I am not a native speaker, so feel free to correct my syntax or rephrase my question.

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• C# Regex stops after first line matched

  - by JD Guzman

  Ok so I have a regex and I need it to find matches in a multiline string. This is the string I am using: Device Identifier: disk0 Device Node: /dev/disk0 Part of Whole: disk0 Device / Media Name: OCZ-VERTEX2 Media Volume Name: Not applicable (no file system) Mounted: Not applicable (no file system) File System: None Content (IOContent): GUID_partition_scheme OS Can Be Installed: No Media Type: Generic Protocol: SATA SMART Status: Verified Total Size: 240.1 GB (240057409536 Bytes) (exactly 468862128 512-Byte-Blocks) Volume Free Space: Not applicable (no file system) Device Block Size: 512 Bytes Read-Only Media: No Read-Only Volume: Not applicable (no file system) Ejectable: No Whole: Yes Internal: Yes Solid State: Yes OS 9 Drivers: No Low Level Format: Not supported Basically I need to separate each line into two groups with the colon as the separator. The regex I am using is: @"([A-Za-z0-9\(\) \-\/]+):([A-Za-z0-9\(\) \-\/]+).*" It does work but only picks up the first line and separates it into the two groups like I want but it stops at that point. I have tried the Multiline option but it doesn't make any difference. I must admit I am new to the regex world. Any help is appreciated.

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• Improving method to read signed 8-bit integers from hexadecimal.

  - by JYelton

  Scenario: I have a string of hexadecimal characters which encode 8-bit signed integers. Each two characters represent a byte which employ the leftmost (MSB) bit as the sign (rather than two's complement). I am converting these to signed ints within a loop and wondered if there's a better way to do it. There are too many conversions and I am sure there's a more efficient method that I am missing. Current Code: string strData = "FFC000407F"; // example input data, encodes: -127, -64, 0, 64, 127 int v; for (int x = 0; x < strData.Length/2; x++) { v = HexToInt(strData.Substring(x * 2, 2)); Console.WriteLine(v); // do stuff with v } private int HexToInt(string _hexData) { string strBinary = Convert.ToString(Convert.ToInt32(_hexData, 16), 2).PadLeft(_hexData.Length * 4, '0'); int i = Convert.ToInt32(strBinary.Substring(1, 7), 2); i = (strBinary.Substring(0, 1) == "0" ? i : -i); return i; } Question: Is there a more streamlined and direct approach to reading two hex characters and converting them to an int when they represent a signed int (-127 to 127) using the leftmost bit as the sign?

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• Where to put external archives to configure running in Eclipse?

  - by Buggieboy

  As a Java/Eclipse noob coming from a Visual Studio .NET background, I'm trying to understand how to set up my run/debug environment in the Eclipse IDE so I can start stepping through code. I have built my application with separate src and bin hierarchies for each library project, and each project has its own jar. For example, in a Windows environment, I have something like: c:\myapp\myapp_main\src\com\mycorp\myapp\main ...and a parallel "bin" tree like this: c:\myapp\myapp_main\bin\com\mycorp\myapp\main Other supporting projects are, similarly: **c:\myapp\myapp_util\src\com\mycorp\myapp\uti**l (and a parallel "bin" tree.) ... etc. So, I end up with, e.g., myapp_util.jar in the ...\myapp_util\bin... path and then add that as an external archive to my myapp_main project. I also use utilities like gluegen-rt.jar, which I add ad external dependencies to the projects requiring them. I have been able to run outside of the Eclipse environment, by copying all my project jars, gluegen-rt DLL, etc., into a "lib" subfolder of some directory and executing something like: java -Djava.library.path=lib -DfullScreen=false -cp lib/gluegen-rt.jar;lib/myapp_main.jar;lib/myapp_util.jar; com.mycorp.myapp.Main When I first pressed F11 to debug, however, I got a message about something like /com/sun/../glugen... not being found by the class loader. So, to debug, or even just run, in Ecplipse, I tried setting up my VM arguments in the Galileo Debug - (Run/Debug) Configurations to be the command line above, beginning at "-Djava.libary.path...". I've put a lib subdirectory - just like the above with all jars and the native gluegen DLL - in various places, such as beneath the folder that my main jar is built in and as a subfolder of my Ecplipse starting workspace folder, but now Eclipse can't find the main class: java.lang.NoClassDefFoundError: com.mycorp.myapp.Main Although the Classpath says that it is using the "default classpath", whatever that is. Bottom line, how do I assemble the constituent files of a multi-project application so that I can run or debug in Ecplipse?

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• [C#] Improving method to read signed 8-bit integers from hexadecimal.

  - by JYelton

  Scenario: I have a string of hexadecimal characters which encode 8-bit signed integers. Each two characters represent a byte which employ the leftmost (MSB) bit as the sign (rather than two's complement). I am converting these to signed ints within a loop and wondered if there's a better way to do it. There are too many conversions and I am sure there's a more efficient method that I am missing. Current Code: string strData = "FFC000407F"; // example input data, encodes: -127, -64, 0, 64, 127 int v; for (int x = 0; x < strData.Length/2; x++) { v = HexToInt(strData.Substring(x * 2, 2)); Console.WriteLine(v); // do stuff with v } private int HexToInt(string _hexData) { string strBinary = Convert.ToString(Convert.ToInt32(_hexData, 16), 2).PadLeft(_hexData.Length * 4, '0'); int i = Convert.ToInt32(strBinary.Substring(1, 7), 2); i = (strBinary.Substring(0, 1) == "0" ? i : -i); return i; } Question: Is there a more streamlined and direct approach to reading two hex characters and converting them to an int when they represent a signed int (-127 to 127) using the leftmost bit as the sign?

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• Am I correctly extracting JPEG binary data from this mysqldump?

  - by Glenn

  I have a very old .sql backup of a vbulletin site that I ran around 8 years ago. I am trying to see the file attachments that are stored in the DB. The script below extracts them all and is verified to be JPEG by hex dumping and checking the SOI (start of image) and EOI (end of image) bytes (FFD8 and FFD9, respectively) according to the JPEG wiki page. But when I try to open them with evince, I get this message "Error interpreting JPEG image file (JPEG datastream contains no image)" What could be going on here? Some background info: sqldump is around 8 years old vbulletin 2.x was the software that stored the info most likely php 4 was used most likely mysql 4.0, possibly even 3.x the column datatype these attachments are stored in is mediumtext My Python 3.1 script: #!/usr/bin/env python3.1 import re trim_l = re.compile(b"""^INSERT INTO attachment VALUES\('\d+', '\d+', '\d+', '(.+)""") trim_r = re.compile(b"""(.+)', '\d+', '\d+'\);$""") extractor = re.compile(b"""^(.*(?:\.jpe?g|\.gif|\.bmp))', '(.+)$""") with open('attachments.sql', 'rb') as fh: for line in fh: data = trim_l.findall(line)[0] data = trim_r.findall(data)[0] data = extractor.findall(data) if data: name, data = data[0] try: filename = 'files/%s' % str(name, 'UTF-8') ah = open(filename, 'wb') ah.write(data) except UnicodeDecodeError: continue finally: ah.close() fh.close() update The JPEG wiki page says FF bytes are section markers, with the next byte indicating the section type. I see some that are not listed in the wiki page (specifically, I see a lot of 5C bytes, so FF5C). But the list is of "common markers" so I'm trying to find a more complete list. Any guidance here would also be appreciated.

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• How to estimate size of data to transfer when using DbCommand.ExecuteXXX?

  - by Yadyn

  I want to show the user detailed progress information when performing potentially lengthy database operations. Specifically, when inserting/updating data that may be on the order of hundreds of KB or MB. Currently, I'm using in-memory DataTables and DataRows which are then synced with the database via TableAdapter.Update calls. This works fine and dandy, but the single call leaves little opportunity to glean any kind of progress info to show to the user. I have no idea how much data is passing through the network to the remote DB or its progress. Basically, all I know is when Update returns and it is assumed complete (barring any errors or exceptions). But this means all I can show is 0% and then a pause and then 100%. I can count the number of rows, even going so far to cound how many are actually Modified or Added, and I could even maybe calculate per DataRow its estimated size based on the datatype of each column, using sizeof for value types like int and checking length for things like strings or byte arrays. With that, I could probably determine, before updating, an estimated total transfer size, but I'm still stuck without any progress info once Update is called on the TableAdapter. Am I stuck just using an indeterminate progress bar or mouse waiting cursor? Would I need to radically change our data access layer to be able to hook into this kind of information? Even if I can't get it down to the precise KB transferred (like a web browser file download progress bar), could I at least know when each DataRow/DataTable finishes or something? How do you best show this kind of progress info using ADO.NET?

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• How can I check whether Exposé is being activated or not?

  - by yangumi

  Hi, I'm creating an application that emulates MacBook's multi-touch Trackpad. As you may know, on MacBook's trackpad if you swipe 4 fingers up, it triggers the Show Desktop. if you swipe 4 fingers down, it shows the Exposé. However, if the Show Desktop is being activated and you swipe 4 fingers down, it will come back to the normal mode. The same goes with the Exposé: if the Exposé is being activated and you swipe 4 fingers up, it will also come back to the normal mode. Here is the problem: I use the keyboard shortcut F3 to show the Exposé and F11 to show the Show Desktop. The problem is, when the Show Desktop is being activated, if I press F3, it will go straight to the Exposé. And when the Exposé is being activated, if I press F11 it will go straight to the Show Desktop. But I want it to behave like Trackpad, which I guess its code may look like this - FourFingersDidSwipeUp { if (isExposeBeingActivated() || isShowDesktopBeingActivated()) { pressKey("Esc"); } else { pressKey("F11"); } } But I don't know how to implement the "isExposeBeingActivated()" and "isShowDesktopBeingActivated()" methods. I've tried creating a window and check whether its size has changed (on assumption that if the Expose is being activated, its size should be smaller), but the system always returns the same size. I tried monitoring the background processes during the Expose, but nothing happened. Does anyknow have any suggestions on this? (I'm sorry if my English sounds weird.)

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• Why use SQL database?

  - by martinthenext

  I'm not quite sure stackoverflow is a place for such a general question, but let's give it a try. Being exposed to the need of storing application data somewhere, I've always used MySQL or sqlite, just because it's always done like that. As it seems like the whole world is using these databases, most of all software products, frameworks, etc. It is rather hard for a beginning developer like me to ask a question - why? Ok, say we have some object-oriented logic in our application, and objects are related to each other somehow. We need to map this logic to the storage logic, so we need relations between database objects too. This leads us to using relational database and I'm ok with that - to put it simple, our database rows sometimes will need to have references to other tables' rows. But why do use SQL language for interaction with such a database? SQL query is a text message. I can understand this is cool for actually understanding what it does, but isn't it silly to use text table and column names for a part of application that no one ever seen after deploynment? If you had to write a data storage from scratch, you would have never used this kind of solution. Personally, I would have used some 'compiled db query' bytecode, that would be assembled once inside a client application and passed to the database. And it surely would name tables and colons by id numbers, not ascii-strings. In the case of changes in table structure those byte queries could be recompiled according to new db schema, stored in XML or something like that. What are the problems of my idea? Is there any reason for me not to write it myself and to use SQL database instead?

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• Combining SQL Rows

  - by lumberjack4

  I've got SQL Compact Database that contains a table of IP Packet Headers. The Table looks like this: Table: PacketHeaders ID SrcAddress SrcPort DestAddress DestPort Bytes 1 10.0.25.1 255 10.0.25.50 500 64 2 10.0.25.50 500 10.0.25.1 255 80 3 10.0.25.50 500 10.0.25.1 255 16 4 75.48.0.25 387 74.26.9.40 198 72 5 74.26.9.40 198 75.48.0.25 387 64 6 10.0.25.1 255 10.0.25.50 500 48 I need to perform a query to show 'conversations' going on across a local network. Packets going from A - B is part of the same conversations as packets going from B - A. I need to perform a query to show the on going conversations. Basically what I need is something that looks like this: Returned Query: SrcAddress SrcPort DestAddress DestPort TotalBytes BytesA->B BytesB->A 10.0.25.1 255 10.0.25.50 500 208 112 96 75.48.0.25 387 74.26.9.40 198 136 72 64 As you can see I need the query (or series of queries) to recognize that A-B is the same as B-A and break up the byte counts accordingly. I'm not a SQL guru by any means but any help on this would be greatly appreciated.

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• ASP.net download page

  - by Russel

  Hi I have a Reports.aspx ASP.NET page that allows users to download excel report files by clicking on several hyperlinks. When a report hyperlink is clicked, I open a new window using the javascript window.open method and navigate off to the download.aspx page. The code-behind for the download page creates a excel file on the fly using openxml(in memory) and send it back to the browser. Here is some code from the download.aspx page: byte[] outputFileBytes = CreateExcelReport().ToArray(); Response.Clear(); Response.BufferOutput = true; Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"; Response.AddHeader("Content-Disposition", string.Format("attachment; filename={0}", "tempReport.xlsx")); Response.BinaryWrite(outputFileBytes); Response.Flush(); Response.Close(); Response.End(); My problem : Some of these reports take some time to generate. I would like to display a loading.gif file on my Reports.aspx page, while the download.aspx page is requested. Once the page request is completed, the loading.gif file should be made invisible. Is there a way to achieve this. Perhaps some kind of event. I have mootools to my disposal. Thanks PS. I know that generating reports like this is not ideal, but thats a different story all together...

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• PostgreSQL: BYTEA vs OID+Large Object?

  - by mlaverd

  I started an application with Hibernate 3.2 and PostgreSQL 8.4. I have some byte[] fields that were mapped as @Basic (= PG bytea) and others that got mapped as @Lob (=PG Large Object). Why the inconsistency? Because I was a Hibernate noob. Now, those fields are max 4 Kb (but average is 2-3 kb). The PostgreSQL documentation mentioned that the LOs are good when the fields are big, but I didn't see what 'big' meant. I have upgraded to PostgreSQL 9.0 with Hibernate 3.6 and I was stuck to change the annotation to @Type(type="org.hibernate.type.PrimitiveByteArrayBlobType"). This bug has brought forward a potential compatibility issue, and I eventually found out that Large Objects are a pain to deal with, compared to a normal field. So I am thinking of changing all of it to bytea. But I am concerned that bytea fields are encoded in Hex, so there is some overhead in encoding and decoding, and this would hurt the performance. Are there good benchmarks about the performance of both of these? Anybody has made the switch and saw a difference?

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• Q on Python serialization/deserialization

  - by neil

  What chances do I have to instantiate, keep and serialize/deserialize to/from binary data Python classes reflecting this pattern (adopted from RFC 2246 [TLS]): enum { apple, orange } VariantTag; struct { uint16 number; opaque string<0..10>; /* variable length */ } V1; struct { uint32 number; opaque string[10]; /* fixed length */ } V2; struct { select (VariantTag) { /* value of selector is implicit */ case apple: V1; /* VariantBody, tag = apple */ case orange: V2; /* VariantBody, tag = orange */ } variant_body; /* optional label on variant */ } VariantRecord; Basically I would have to define a (variant) class VariantRecord, which varies depending on the value of VariantTag. That's not that difficult. The challenge is to find a most generic way to build a class, which serializes/deserializes to and from a byte stream... Pickle, Google protocol buffer, marshal is all not an option. I made little success with having an explicit "def serialize" in my class, but I'm not very happy with it, because it's not generic enough. I hope I could express the problem. My current solution in case VariantTag = apple would look like this, but I don't like it too much import binascii import struct class VariantRecord(object): def __init__(self, number, opaque): self.number = number self.opaque = opaque def serialize(self): out = struct.pack('>HB%ds' % len(self.opaque), self.number, len(self.opaque), self.opaque) return out v = VariantRecord(10, 'Hello') print binascii.hexlify(v.serialize()) >> 000a0548656c6c6f Regards

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• How can I read a DBF file with incorrectly defined column data types using ADO.NET?

  - by Jason

  I have a several DBF files generated by a third party that I need to be able to query. I am having trouble because all of the column types have been defined as characters, but the data within some of these fields actually contain binary data. If I try to read these fields using an OleDbDataReader as anything other than a string or character array, I get an InvalidCastException thrown, but I need to be able to read them as a binary value or at least cast/convert them after they are read. The columns that actually DO contain text are being returned as expected. For example, the very first column is defined as a character field with a length of 2 bytes, but the field contains a 16-bit integer. I have written the following test code to read the first column and convert it to the appropriate data type, but the value is not coming out right. The first row of the database has a value of 17365 (0x43D5) in the first column. Running the following code, what I end up getting is 17215 (0x433F). I'm pretty sure it has to do with using the ASCII encoding to get the bytes from the string returned by the data reader, but I'm not sure of another way to get the value into the format that I need, other that to write my own DBF reader and bypass ADO.NET altogether which I don't want to do unless I absolutely have to. Any help would be greatly appreciated. byte[] c0; int i0; string con = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\ASTM;Extended Properties=dBASE III;User ID=Admin;Password=;"; using (OleDbConnection c = new OleDbConnection(con)) { c.Open(); OleDbCommand cmd = c.CreateCommand(); cmd.CommandText = "SELECT * FROM astm2007"; OleDbDataReader dr = cmd.ExecuteReader(); while (dr.Read()) { c0 = Encoding.ASCII.GetBytes(dr.GetValue(0).ToString()); i0 = BitConverter.ToInt16(c0, 0); } dr.Dispose(); }

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• My OpenCL kernel is slower on faster hardware.. But why?

  - by matdumsa

  Hi folks, As I was finishing coding my project for a multicore programming class I came up upon something really weird I wanted to discuss with you. We were asked to create any program that would show significant improvement in being programmed for a multi-core platform. I’ve decided to try and code something on the GPU to try out OpenCL. I’ve chosen the matrix convolution problem since I’m quite familiar with it (I’ve parallelized it before with open_mpi with great speedup for large images). So here it is, I select a large GIF file (2.5 MB) [2816X2112] and I run the sequential version (original code) and I get an average of 15.3 seconds. I then run the new OpenCL version I just wrote on my MBP integrated GeForce 9400M and I get timings of 1.26s in average.. So far so good, it’s a speedup of 12X!! But now I go in my energy saver panel to turn on the “Graphic Performance Mode” That mode turns off the GeForce 9400M and turns on the Geforce 9600M GT my system has. Apple says this card is twice as fast as the integrated one. Guess what, my timing using the kick-ass graphic card are 3.2 seconds in average… My 9600M GT seems to be more than two times slower than the 9400M.. For those of you that are OpenCL inclined, I copy all data to remote buffers before starting, so the actual computation doesn’t require roundtrip to main ram. Also, I let OpenCL determine the optimal local-worksize as I’ve read they’ve done a pretty good implementation at figuring that parameter out.. Anyone has a clue? edit: full source code with makefiles here http://www.mathieusavard.info/convolution.zip cd gimage make cd ../clconvolute make put a large input.gif in clconvolute and run it to see results

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• Using RecordStore in Java J2ME

  - by me123

  Hi, I am currently doing some J2ME development. I am having a problem in that a user can add and remove elements to the record store, and if a record gets deleted, then that record is left empty and the others don't move up one. I'm trying to come up with a loop that will check if a record has anything in it (incase it has been deleted) and if it does then I want to add the contents of that record to a list. My code is similar to as follows: for (int i = 1; i <= rs.getNumRecords(); i++) { // Re-allocate if necessary if (rs.getRecordSize(i) > recData.length) recData = new byte[rs.getRecordSize(i)]; len = rs.getRecord(i, recData, 0); st = new String(recData, 0, len); System.out.println("Record #" + i + ": " + new String(recData, 0, len)); System.out.println("------------------------------"); if(st != null) { list.insert(i-1, st, null); } } When it gets to rs.getRecordSize(i), I always get a "javax.microedition.rms.InvalidRecordIDException: error finding record". I know this is due to the record being empty but I can't think of a way to get around this problem. Any help would be much appreciated. Thanks in advance.

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• Porting an IBXpress Interbase 6 app to the current Firebird platform, on Delphi 7?

  - by robsoft

  Just wondering if there are any gotchas to be wary of here. We have a legacy D7 app that we developed several years ago for a client, which uses IBXpress to talk to the open source Interbase 6 build. We're having a number of issues with that platform these days (very slow to connect/start-up on new hardware being the chief one) and the client has okayed spending some time/money moving the database over to Firebird. We really DON'T want to embark upon moving it to D2010 (or D2007 which would be my preference right now) as we figure that we might have to move the database layer from IBXpress to something else to best suit Firebird anyway. And at the end of the day, the client is only looking to lessen the database pain, not overhaul/upgrade/rewrite the app. Given the ancestry of Firebird, is it a fairly painless, well-understood path from IBXpress Interbase 6 to (whatever) with Firebird? We have quite a number of sprocs, triggers (and even datatypes) etc in the existing IB database already (and the client has a number of paying customers all using this platform) so we felt that going to Firebird was more likely to be a smoother move than moving to SQL Express (or another flavour of DB entirely). Note that we're not looking for 'embedded' DB advocacy - in many of our client's customers' installations, the software is used in a multi-user client-server way so keeping that kind of approach is important.

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• Java UTF-8 to ASCII conversion with supplements

  - by bozo

  Hi, we are accepting all sorts of national characters in UTF-8 string on the input, and we need to convert them to ASCII string on the output for some legacy use. (we don't accept Chinese and Japanese chars, only European languages) We have a small utility to get rid of all the diacritics: public static final String toBaseCharacters(final String sText) { if (sText == null || sText.length() == 0) return sText; final char[] chars = sText.toCharArray(); final int iSize = chars.length; final StringBuilder sb = new StringBuilder(iSize); for (int i = 0; i < iSize; i++) { String sLetter = new String(new char[] { chars[i] }); sLetter = Normalizer.normalize(sLetter, Normalizer.Form.NFC); try { byte[] bLetter = sLetter.getBytes("UTF-8"); sb.append((char) bLetter[0]); } catch (UnsupportedEncodingException e) { } } return sb.toString(); } The question is how to replace all the german sharp s (ß, Ð, d) and other characters that get through the above normalization method, with their supplements (in case of ß, supplement would probably be "ss" and in case od Ð supplement would be either "D" or "Dj"). Is there some simple way to do it, without million of .replaceAll() calls? So for example: Ðonardan = Djonardan, Blaß = Blass and so on. We can replace all "problematic" chars with empty space, but would like to avoid this to make the output as similar to the input as possible. Thank you for your answers, Bozo

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• Node.js/ v8: How to make my own snapshot to accelerate startup

  - by Anand

  I have a node.js (v0.6.12) application that starts by evaluating a Javascript file, startup.js. It takes a long time to evaluate startup.js, and I'd like to 'bake it in' to a custom build of Node if possible. The v8 source directory distributed with Node, node/deps/v8/src, contains a SconScript that can almost be used to do this. On line 302, we have LIBRARY_FILES = ''' runtime.js v8natives.js array.js string.js uri.js math.js messages.js apinatives.js date.js regexp.js json.js liveedit-debugger.js mirror-debugger.js debug-debugger.js '''.split() Those javascript files are present in the same directory. Something in the build process apparently evaluates them, takes a snapshot of state, and saves it as a byte string in node/out/Release/obj/release/snapshot.cc (on Mac OS). Some customization of the startup snapshot is possible by altering the SconScript. For example, I can change the definition of the builtin Date.toString by altering date.js. I can even add new global variables by adding startup.js to the list of library files, with contents global.test = 1. However, I can't put just any javascript code in startup.js. If it contains Date.toString = 1;, an error results even though the code is valid at the node repl: Build failed: -> task failed (err #2): {task: libv8.a SConstruct -> libv8.a} make: *** [program] Error 1 And it obviously can't make use of code that depends on libraries Node adds to v8. global.underscore = require('underscore'); causes the same error. I'd ideally like a tool, customSnapshot, where customSnapshot startup.js evaluates startup.js with node and then dumps a snapshot to a file, snapshot.cc, which I can put into the node source directory. I can then build node and tell it not to rebuild the snapshot.

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