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• FILESTREAM/FILETABLE Clarifications for Implementation

  - by user1209734

  Recently our team was looking at FILESTREAM to expand the capabilities of our proprietary application. The main purpose of this app is managing the various PDFS, Images and documents to all of the parts we manufacture. Our ASP application uses a few third party tools to allow viewing of these files. We currently have 980GB of data on the Fileserver. We have around 200GB of Binary data in SQL Server that we would like to extract since it is not performing well hence FILESTREAM seems to be a good compromise to the two major data storage/access issues. A few things are not exactly clear to us: FILESTREAM Can or Cannot store its data on a drive that is not locally attached. We already have a File Server with a RAID 10 (1.5TB drives). This server stores all of the documents right now, would we have to move these drives to the SQL Server for FILESTREAM? That would be a tough bullet to bite since the server also is doubling as the Application Server (Two VMs on one physical server). FILETABLE stores the common metadata about the files but where is the Full Text part of it stored to allow searching of files like doc/docx? Is this separate? Are you able to freely add criteria to this to search by? If so any links to clarify would be appreciated. Can FILETABLE be referenced in another table with a foreign key? Thank you in advance EDIT: For those having these questions this web video covered everything and more in terms of explaining filestream from 2008 to 2012 and the cavets to consider (I would seriously rep him if I could): http://channel9.msdn.com/Events/TechDays/Techdays-2012-the-Netherlands/2270 In conclusion we will not be using FILESTREAM as it would be way to huge of an upsurge to accommodate for investment. EDIT 2: Update to #1 - After carefully assessing FileTable in addition to FILESTREAM we got a winning combination. We did have to move the files over to the new server (wasn't to painful since they were on the same VM).It honestly took more time to write an extraction tool to dump the binary data within SQL to the File System. Update to #2 - This was seperate but again Bob had an excellent webinar explaining this: http://channel9.msdn.com/Events/TechEd/Europe/2012/DBI411 Update to #3 - Using TFT inheritance we recycled the Docs table we had (minus the huge binary blobs) which required very little changes in our legacy apps. This was a huge upshot for the developer team.

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• Databinding to ObservableCollection in a different UserControl?

  - by Dave

  Question re-written on 2010-03-24 I have two UserControls, where one is a dialog that has a TabControl, and the other is one that appears within said TabControl. I'll just call them CandyDialog and CandyNameViewer for simplicity's sake. There's also a data management class called Tracker that manages information storage, which for all intents and purposes just exposes a public property that is an ObservableCollection. I display the CandyNameViewer in CandyDialog via code behind, like this: private void CandyDialog_Loaded( object sender, RoutedEventArgs e) { _candyviewer = new CandyViewer(); _candyviewer.DataContext = _tracker; candy_tab.Content = _candyviewer; } The CandyViewer's XAML looks like this (edited for kaxaml): <Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"> <Page.Resources> <DataTemplate x:Key="CandyItemTemplate"> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition Width="120"></ColumnDefinition> <ColumnDefinition Width="150"></ColumnDefinition> </Grid.ColumnDefinitions> <TextBox Grid.Column="0" Text="{Binding CandyName}" Margin="3"></TextBox> <!-- just binding to DataContext ends up using InventoryItem as parent, so we need to get to the UserControl --> <ComboBox Grid.Column="1" SelectedItem="{Binding SelectedCandy, Mode=TwoWay}" ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.CandyNames}" Margin="3"></ComboBox> </Grid> </DataTemplate> </Page.Resources> <Grid> <ListBox DockPanel.Dock="Top" ItemsSource="{Binding CandyBoxContents, Mode=TwoWay}" ItemTemplate="{StaticResource CandyItemTemplate}" /> </Grid> </Page> Now everything works fine when the controls are loaded. As long as CandyNames is populated first, and then the consumer UserControl is displayed, all of the names are there. I obviously don't get any errors in the Output Window or anything like that. The issue I have is that when the ObservableCollection is modified from the model, those changes are not reflected in the consumer UserControl! I've never had this problem before; all of my previous uses of ObservableCollection updated fine, although in those cases I wasn't databinding across assemblies. Although I am currently only adding and removing candy names to/from the ObservableCollection, at a later date I will likely also allow renaming from the model side. Is there something I did wrong? Is there a good way to actually debug this? Reed Copsey indicates here that inter-UserControl databinding is possible. Unfortunately, my favorite Bea Stollnitz article on WPF databinding debugging doesn't suggest anything that I could use for this particular problem.

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• PostgreSQL to Data-Warehouse: Best approach for near-real-time ETL / extraction of data

  - by belvoir

  Background: I have a PostgreSQL (v8.3) database that is heavily optimized for OLTP. I need to extract data from it on a semi real-time basis (some-one is bound to ask what semi real-time means and the answer is as frequently as I reasonably can but I will be pragmatic, as a benchmark lets say we are hoping for every 15min) and feed it into a data-warehouse. How much data? At peak times we are talking approx 80-100k rows per min hitting the OLTP side, off-peak this will drop significantly to 15-20k. The most frequently updated rows are ~64 bytes each but there are various tables etc so the data is quite diverse and can range up to 4000 bytes per row. The OLTP is active 24x5.5. Best Solution? From what I can piece together the most practical solution is as follows: Create a TRIGGER to write all DML activity to a rotating CSV log file Perform whatever transformations are required Use the native DW data pump tool to efficiently pump the transformed CSV into the DW Why this approach? TRIGGERS allow selective tables to be targeted rather than being system wide + output is configurable (i.e. into a CSV) and are relatively easy to write and deploy. SLONY uses similar approach and overhead is acceptable CSV easy and fast to transform Easy to pump CSV into the DW Alternatives considered .... Using native logging (http://www.postgresql.org/docs/8.3/static/runtime-config-logging.html). Problem with this is it looked very verbose relative to what I needed and was a little trickier to parse and transform. However it could be faster as I presume there is less overhead compared to a TRIGGER. Certainly it would make the admin easier as it is system wide but again, I don't need some of the tables (some are used for persistent storage of JMS messages which I do not want to log) Querying the data directly via an ETL tool such as Talend and pumping it into the DW ... problem is the OLTP schema would need tweaked to support this and that has many negative side-effects Using a tweaked/hacked SLONY - SLONY does a good job of logging and migrating changes to a slave so the conceptual framework is there but the proposed solution just seems easier and cleaner Using the WAL Has anyone done this before? Want to share your thoughts?

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• Issues with MIPS interrupt for tv remote simulator

  - by pred2040

  Hello I am writing a program for class to simulate a tv remote in a MIPS/SPIM enviroment. The functions of the program itself are unimportant as they worked fine before the interrupt so I left them all out. The gaol is basically to get a input from the keyboard by means of interupt, store it in $s7 and process it. The interrupt is causing my program to repeatedly spam the errors: Exception occurred at PC=0x00400068 Bad address in data/stack read: 0x00000004 Exception occurred at PC=0x00400358 Bad address in data/stack read: 0x00000000 program starts here .data msg_tvworking: .asciiz "tv is working\n" msg_sec: .asciiz "sec -- " msg_on: .asciiz "Power On" msg_off: .asciiz "Power Off" msg_channel: .asciiz " Channel " msg_volume: .asciiz " Volume " msg_sleep: .asciiz " Sleep Timer: " msg_dash: .asciiz "-\n" msg_newline: .asciiz "\n" msg_comma: .asciiz ", " array1: .space 400 # 400 bytes of storage for 100 channels array2: .space 400 # copy of above for sorting var1: .word 0 # 1 if 0-9 is pressed, 0 if not var2: .word 0 # stores number of channel (ex. 2-) var3: .word 0 # channel timer var4: .word 0 # 1 if s pressed once, 2 if twice, 0 if not var5: .word 0 # sleep wait timer var6: .word 0 # program timer var9: .float 0.01 # for channel timings .kdata var7: .word 10 var8: .word 11 .text .globl main main: li $s0, 300 li $s1, 0 # channel li $s2, 50 # volume li $s3, 1 # power - 1:on 0:off li $s4, 0 # sleep timer - 0:off li $s5, 0 # temporary li $s6, 0 # length of sleep period li $s7, 10000 # current key press li $t2, 0 # temp value not needed across calls li $t4, 0 interrupt data here mfc0 $a0, $12 ori $a0, 0xff11 mtc0 $a0, $12 lui $t0, 0xFFFF ori $a0, $0, 2 sw $a0, 0($t0) mainloop: # 1. get external input, and process it # input from interupt is taken from $a2 and placed in $s7 #for processing beq $a2, $0, next lw $s7, 4($a2) li $a2, 0 # call the process_input function here # jal process_input next: # 2. check sleep timer mainloopnext1: # 3. delay for 10ms jal delay_10ms jal check_timers jal channel_time # 4. print status lw $s5, var6 addi $s5, $s5, 1 sw $s5, var6 addi $s0, $s0, -1 bne $s0, $0, mainloopnext4 li $s0, 300 jal status_print mainloopnext4: j mainloop li $v0,10 # exit syscall -------------------------------------------------- status_print: seconds_stat: power_stat: on_stat: off_stat: channel_stat: volume_stat: sleep_stat: j $ra -------------------------------------------------- delay_10ms: li $t0, 6000 delay_10ms_loop: addi $t0, $t0, -1 bne $t0, $0, delay_10ms_loop jr $ra -------------------------------------------------- check_timers: channel_press: sleep_press: go_back_press: channel_check: channel_ignore: sleep_check: sleep_ignore: j $ra ------------------------------------------------ process_input: beq $s7, 112, power beq $s7, 117, channel_up beq $s7, 100, channel_down beq $s7, 108, volume_up beq $s7, 107, volume_down beq $s7, 115, sleep_init beq $s7, 118, history bgt $s7, 47, end_range jr $ra end_range: power: on: off: channel_up: over: channel_down: under: channel_message: channel_time: volume_up: volume_down: volume_message: sleep_init: sleep_incr: sleep: sleep_reset: history: digit_pad_init: digit_pad: jr $ra -------------------------------------------- interupt data here, followed closely from class .ktext 0x80000180 .set noat move $k1, $at .set at sw $v0, var7 sw $a0, var8 mfc0 $k0, $13 srl $a0, $k0, 2 andi $a0, $a0, 0x1f bne $a0, $zero, no_io lui $v0, 0xFFFF lw $a2, 4($v0) # keyboard data placed in $a2 no_io: mtc0 $0, $13 mfc0 $k0, $12 andi $k0, 0xfffd ori $k0, 0x11 mtc0 $k0, $12 lw $v0, var7 lw $a0, var8 .set noat move $at, $k1 .set at eret Thanks in advance.

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• SQL Server 2008: FileStream Insertion Failure w/ .NET 3.5SP1

  - by James Alexander

  I've configured a db w/ a FileStream group and have a table w/ File type on it. When attempting to insert a streamed file and after I create the table row, my query to read the filepath out and the buffer returns a null file path. I can't seem to figure out why though. Here is the table creation script: /****** Object: Table [dbo].[JobInstanceFile] Script Date: 03/22/2010 18:05:36 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO SET ANSI_PADDING ON GO CREATE TABLE [dbo].[JobInstanceFile]( [JobInstanceFileId] [int] IDENTITY(1,1) NOT NULL, [JobInstanceId] [int] NOT NULL, [File] [varbinary](max) FILESTREAM NULL, [FileId] [uniqueidentifier] ROWGUIDCOL NOT NULL, [Created] [datetime] NOT NULL, CONSTRAINT [PK_JobInstanceFile] PRIMARY KEY CLUSTERED ( [JobInstanceFileId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] FILESTREAM_ON [JobInstanceFilesGroup], UNIQUE NONCLUSTERED ( [FileId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] FILESTREAM_ON [JobInstanceFilesGroup] GO SET ANSI_PADDING OFF GO ALTER TABLE [dbo].[JobInstanceFile] ADD DEFAULT (newid()) FOR [FileId] GO Here's my proc I call to create the row before streaming the file: /****** Object: StoredProcedure [dbo].[JobInstanceFileCreate] Script Date: 03/22/2010 18:06:23 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO create proc [dbo].[JobInstanceFileCreate] @JobInstanceId int, @Created datetime as insert into JobInstanceFile (JobInstanceId, FileId, Created) values (@JobInstanceId, newid(), @Created) select scope_identity() GO And lastly, here's the code I'm using: public int CreateJobInstanceFile(int jobInstanceId, string filePath) { using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["ConsumerMarketingStoreFiles"].ConnectionString)) using (var fileStream = new FileStream(filePath, FileMode.Open)) { connection.Open(); var tran = connection.BeginTransaction(IsolationLevel.ReadCommitted); try { //create the JobInstanceFile instance var command = new SqlCommand("JobInstanceFileCreate", connection) { Transaction = tran }; command.CommandType = CommandType.StoredProcedure; command.Parameters.AddWithValue("@JobInstanceId", jobInstanceId); command.Parameters.AddWithValue("@Created", DateTime.Now); int jobInstanceFileId = Convert.ToInt32(command.ExecuteScalar()); //read out the filestream transaction context to stream the file for storage command.CommandText = "select [File].PathName(), GET_FILESTREAM_TRANSACTION_CONTEXT() from JobInstanceFile where JobInstanceFileId = @JobInstanceFileId"; command.CommandType = CommandType.Text; command.Parameters.AddWithValue("@JobInstanceFileId", jobInstanceFileId); using (SqlDataReader dr = command.ExecuteReader()) { dr.Read(); //get the file path we're writing out to string writePath = dr.GetString(0); using (var writeStream = new SqlFileStream(writePath, (byte[])dr.GetValue(1), FileAccess.ReadWrite)) { //copy from one stream to another byte[] bytes = new byte[65536]; int numBytes; while ((numBytes = fileStream.Read(bytes, 0, 65536)) 0) writeStream.Write(bytes, 0, numBytes); } } tran.Commit(); return jobInstanceFileId; } catch (Exception e) { tran.Rollback(); throw e; } } } Can someone please let me know what I'm doing wrong. In the code, the following expression is returning null for the file path and shouldn't be: //get the file path we're writing out to string writePath = dr.GetString(0); The server is different then the computer the code is running on but the necessary shares appear to be in order and I have also run the following: EXEC sp_configure filestream_access_level, 2 Any help would be greatly appreciated. Thanks!

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• Bazaar newbie question about repository structures

  - by esc1729

  I want to use Bazaar on Windows XP for web-development and related tasks. Most of the files are edited locally and then transferred via FTP to the server. Just now the repository sits on my local workstation. Later on it should be shared locally with some co-workers. Perhaps we will use a local Linux server as a centralized repository, but this structure is not decided for now. But first I need to understand the impacts of the different repository setups, which I do not at all. Using Bazaar-Explorer on Windows XP I’ve created a ‘shared tree repository’ from the option list of the init-dialogue in some location dev-filter/. Bazaar Explorer tells me: Created repository with treeless branches at F:/bzr.local/dev-filter Created branch at F:/bzr.local/dev-filter/trunk Created working tree at F:/bzr.local/dev-filter/work OK so far. Now I move a bunch of files into the work directory and add and commit them as Rev 1 ‘Start Revision’. Then I work on some of these files and commit them again as Rev 2. Here my confusion starts. Shouldn’t both revisions go into the trunk? The trunk is still empty, beside the .bzr directory which only holds some management information. If I delete my working directory, which I have tried during these first experiments, everything is gone. There’s obviously no hidden storage of those files. OK. Perhaps I need to push it into the trunk? This does not work either. Entering the work/ directory and initializing the ‘push’ to the trunk, Bazaar-Explorer tells me No new revisions to push. So what? This looks like a severe conceptual misunderstanding about what should happen on my side. Edit, 2010-02-03: Some conclusions What I learned meanwhile is this: I think I should switch to the command line until I really understand what’s going on, at least for creating the repositories and branches. Bazaar Explorer introduces a new level of abstraction which I only can handle if I understand the level beneath One of the secrets of working with Bazaar at least for me is to understand those .bzr directories, their particular properties and states when created with ‘bzr init’, ‘bzr init-repository’, ‘bzr branch’ etc. in all their variants and how they are plumped together. While there’s a whole chapter of ‘Organizing your workspace’ in the Bazaar User Guide, it’s more or less workflow oriented. The manual contains a lot of directory structures for the given examples. What I would prefer beside this and have not (or only rudimentary) found so far is some graphical representation of those ‘Lego like’ .bzr building blocks which create the linking of all the parts. So I started to invent some simple notation while working through the examples and looking into the .bzr directories to document what information is stored there, where does it come from, how and to what is it linked, is it complete or shared, etc. Erich Schreiber

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• How do I get Visual Studio build process to pass condition to library(external) project

  - by Billy Talented

  I have tried several solutions for this problem. Enough to know I do not know enough about MSBuild to do this elegantly but I feel like there should be a method. I have a set of libraries for working with .net projects. A few of the projects utilize System.Web.Mvc - which recently released Version 2 - and we are looking forward to the upgrade. Currently sites which reference this library reference it directly by the project(csproj) on the developer's computer - not a built version of the library so that changes and source code case easily be viewed when dealing code from this library. This works quite well and would prefer to not have to switch to binary references (but will if this is the only solution). The problem I have is that because of some of the functionality that was added onto the MVC1 based library (view engines, model binders etc) several of the sites reliant on these libraries need to stay on MVC1 until we have full evaluated and tested them on MVC2. I would prefer to not have to fork or have two copies on each dev machine. So what I would like to be able to do is set a property group value in the referencing web application and have this read by the above mentions library with the caviat that when working directly on the library via its containing solution I would like to be able to control this via Configuration Manager by selecting a build type and that property overriding the build behavior of the solution (i.e. 'Debug - MVC1' vs 'Debug -MVC2') - I have this working via: <Choose> <When Condition=" '$(Configuration)|$(Platform)' == 'Release - MVC2|AnyCPU' Or '$(Configuration)|$(Platform)' == 'Debug - MVC2|AnyCPU'"> <ItemGroup> <Reference Include="System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL"> </Reference> <Reference Include="Microsoft.Web.Mvc, Version=1.0.0.0, Culture=neutral, processorArchitecture=MSIL"> <SpecificVersion>False</SpecificVersion> <HintPath>..\Dependancies\Web\MVC2\Microsoft.Web.Mvc.dll</HintPath> </Reference> </ItemGroup> </When> <Otherwise> <ItemGroup> <Reference Include="System.Web.Mvc, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL"> <SpecificVersion>False</SpecificVersion> <HintPath>..\Dependancies\Web\MVC\System.Web.Mvc.dll</HintPath> </Reference> </ItemGroup> </Otherwise> The item that I am struggling with is the cross solution issue(solution TheWebsite references this project and needs to control which build property to use) that I have not found a way to work with that I think is a solid solution that enabled the build within visual studio to work as it has to date. Other bits: we are using VS2008, Resharper, TeamCity for CI, SVN for source control.

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• print a linear linked list into a table

  - by user1796970

  I am attempting to print some values i have stored into a LLL into a readable table. The data i have stored is the following : DEBBIE STARR F 3 W 1000.00 JOAN JACOBUS F 9 W 925.00 DAVID RENN M 3 H 4.75 ALBERT CAHANA M 3 H 18.75 DOUGLAS SHEER M 5 W 250.00 SHARI BUCHMAN F 9 W 325.00 SARA JONES F 1 H 7.50 RICKY MOFSEN M 6 H 12.50 JEAN BRENNAN F 6 H 5.40 JAMIE MICHAELS F 8 W 150.00 i have stored each firstname, lastname, gender, tenure, payrate, and salary into their own List. And would like to be able to print them out in the same format that they are viewed on the text file i read them in from. i have messed around with a few methods that allow me to traverse and print the Lists, but i end up with ugly output. . . here is my code for the storage of the text file and the format i would like to print out: public class Payroll { private LineWriter lw; private ObjectList output; ListNode input; private ObjectList firstname, lastname, gender, tenure, rate, salary; public Payroll(LineWriter lw) { this.lw = lw; this.firstname = new ObjectList(); this.lastname = new ObjectList(); this.gender = new ObjectList(); this.tenure = new ObjectList(); this.rate = new ObjectList(); this.salary = new ObjectList(); this.output = new ObjectList(); this.input = new ListNode(); } public void readfile() { File file = new File("payfile.txt"); try{ Scanner scanner = new Scanner(file); while(scanner.hasNextLine()) { String line = scanner.nextLine(); Scanner lineScanner = new Scanner(line); lineScanner.useDelimiter("\\s+"); while(lineScanner.hasNext()) { firstname.insert1(lineScanner.next()); lastname.insert1(lineScanner.next()); gender.insert1(lineScanner.next()); tenure.insert1(lineScanner.next()); rate.insert1(lineScanner.next()); salary.insert1(lineScanner.next()); } } }catch(FileNotFoundException e) {e.printStackTrace();} } public void printer(LineWriter lw) { String msg = " FirstName " + " LastName " + " Gender " + " Tenure " + " Pay Rate " + " Salary "; output.insert1(msg); System.out.println(output.getFirst()); System.out.println(" " + firstname.getFirst() + " " + lastname.getFirst() + "\t" + gender.getFirst() + "\t" + tenure.getFirst() + "\t" + rate.getFirst() + "\t" + salary.getFirst()); } }

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• NSXMLParser Memory Allocation Efficiency for the iPhone

  - by Staros

  Hello, I've recently been playing with code for an iPhone app to parse XML. Sticking to Cocoa, I decided to go with the NSXMLParser class. The app will be responsible for parsing 10,000+ "computers", all which contain 6 other strings of information. For my test, I've verified that the XML is around 900k-1MB in size. My data model is to keep each computer in an NSDictionary hashed by a unique identifier. Each computer is also represented by a NSDictionary with the information. So at the end of the day, I end up with a NSDictionary containing 10k other NSDictionaries. The problem I'm running into isn't about leaking memory or efficient data structure storage. When my parser is done, the total amount of allocated objects only does go up by about 1MB. The problem is that while the NSXMLParser is running, my object allocation is jumping up as much as 13MB. I could understand 2 (one for the object I'm creating and one for the raw NSData) plus a little room to work, but 13 seems a bit high. I can't imaging that NSXMLParser is that inefficient. Thoughts? Code... The code to start parsing... NSXMLParser *parser = [[NSXMLParser alloc] initWithData: data]; [parser setDelegate:dictParser]; [parser parse]; output = [[dictParser returnDictionary] retain]; [parser release]; [dictParser release]; And the parser's delegate code... -(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict { if(mutableString) { [mutableString release]; mutableString = nil; } mutableString = [[NSMutableString alloc] init]; } -(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string { if(self.mutableString) { [self.mutableString appendString:string]; } } -(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName { if([elementName isEqualToString:@"size"]){ //The initial key, tells me how many computers returnDictionary = [[NSMutableDictionary alloc] initWithCapacity:[mutableString intValue]]; } if([elementName isEqualToString:hashBy]){ //The unique identifier if(mutableDictionary){ [mutableDictionary release]; mutableDictionary = nil; } mutableDictionary = [[NSMutableDictionary alloc] initWithCapacity:6]; [returnDictionary setObject:[NSDictionary dictionaryWithDictionary:mutableDictionary] forKey:[NSMutableString stringWithString:mutableString]]; } if([fields containsObject:elementName]){ //Any of the elements from a single computer that I am looking for [mutableDictionary setObject:mutableString forKey:elementName]; } } Everything initialized and released correctly. Again, I'm not getting errors or leaking. Just inefficient. Thanks for any thoughts!

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• NoHostAvailableException With Cassandra & DataStax Java Driver If Large ResultSet

  - by hughj

  The setup: 2-node Cassandra 1.2.6 cluster replicas=2 very large CQL3 table with no secondary index Rowkey is a UUID.randomUUID().toString() read consistency set to ONE Using DataStax java driver 1.0 The request: Attempting to do a table scan by "SELECT some-col from schema.table LIMIT nnn;" The fail: Once I go beyond a certain nnn LIMIT, I start to get NoHostAvailableExceptions from the driver. It reads like this: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /10.181.13.239 ([/10.181.13.239] Unexpected exception triggered)) at com.datastax.driver.core.exceptions.NoHostAvailableException.copy(NoHostAvailableException.java:64) at com.datastax.driver.core.ResultSetFuture.extractCauseFromExecutionException(ResultSetFuture.java:214) at com.datastax.driver.core.ResultSetFuture.getUninterruptibly(ResultSetFuture.java:169) at com.jpmc.es.rtm.storage.impl.EventExtract.main(EventExtract.java:36) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120) Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /10.181.13.239 ([/10.181.13.239] Unexpected exception triggered)) at com.datastax.driver.core.RequestHandler.sendRequest(RequestHandler.java:98) at com.datastax.driver.core.RequestHandler$1.run(RequestHandler.java:165) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) Given: This is probably not the most enlightened thing to do to a large table with millions of rows, but this is how I learn what not to do, so I would really appreciate someone who could volunteer how this kind of error can be debugged. For example, when this happens, there are no indications that the nodes in the cluster ever had an issue with the request (there is nothing in the logs on either node that indicate any timeout or failure). Also, I enabled the trace on the driver, which gives you some nice autotrace (ala Oracle) info as long as the query succeeds. But in this case, the driver blows a NoHostAvailableException and no ExecutionInfo is available, so tracing has not provided any benefit in this case. I also find it interesting that this does not seem to be recorded as a timeout (my JMX consoles tell me no timeouts have occurred). So, I am left not understanding WHERE the failure is actually occurring. I am left with the idea that it is the driver that is having a problem, but I don't know how to debug it (and I would really like to). I have read several posts from folks that state that query'g for resultSets 10000 rows is probably not a good idea, and I am willing to accept this, but I would like to understand what is causing the exception and where the exception is happening. FWIW, I also tried bumping the timeout properties in the cassandra.yaml, but this made no difference whatsoever. I welcome any suggestions, anecdotes, insults, or monetary contributions for my registration in the house of moron-developers. Regards!!

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• Creating thousands of records in Rails

  - by willCosgrove

  Let me set the stage: My application deals with gift cards. When we create cards they have to have a unique string that the user can use to redeem it with. So when someone orders our gift cards, like a retailer, we need to make a lot of new card objects and store them in the DB. With that in mind, I'm trying to see how quickly I can have my application generate 100,000 Cards. Database expert, I am not, so I need someone to explain this little phenomena: When I create 1000 Cards, it takes 5 seconds. When I create 100,000 cards it should take 500 seconds right? Now I know what you're wanting to see, the card creation method I'm using, because the first assumption would be that it's getting slower because it's checking the uniqueness of a bunch of cards, more as it goes along. But I can show you my rake task desc "Creates cards for a retailer" task :order_cards, [:number_of_cards, :value, :retailer_name] => :environment do |t, args| t = Time.now puts "Searching for retailer" @retailer = Retailer.find_by_name(args[:retailer_name]) puts "Retailer found" puts "Generating codes" value = args[:value].to_i number_of_cards = args[:number_of_cards].to_i codes = [] top_off_codes(codes, number_of_cards) while codes != codes.uniq codes.uniq! top_off_codes(codes, number_of_cards) end stored_codes = Card.all.collect do |c| c.code end while codes != (codes - stored_codes) codes -= stored_codes top_off_codes(codes, number_of_cards) end puts "Codes are unique and generated" puts "Creating bundle" @bundle = @retailer.bundles.create!(:value => value) puts "Bundle created" puts "Creating cards" @bundle.transaction do codes.each do |code| @bundle.cards.create!(:code => code) end end puts "Cards generated in #{Time.now - t}s" end def top_off_codes(codes, intended_number) (intended_number - codes.size).times do codes << ReadableRandom.get(CODE_LENGTH) end end I'm using a gem called readable_random for the unique code. So if you read through all of that code, you'll see that it does all of it's uniqueness testing before it ever starts creating cards. It also writes status updates to the screen while it's running, and it always sits for a while at creating. Meanwhile it flies through the uniqueness tests. So my question to the stackoverflow community is: Why is my database slowing down as I add more cards? Why is this not a linear function in regards to time per card? I'm sure the answer is simple and I'm just a moron who knows nothing about data storage. And if anyone has any suggestions, how would you optimize this method, and how fast do you think you could get it to create 100,000 cards? (When I plotted out my times on a graph and did a quick curve fit to get my line formula, I calculated how long it would take to create 100,000 cards with my current code and it says 5.5 hours. That maybe completely wrong, I'm not sure. But if it stays on the line I curve fitted, it would be right around there.)

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• stdio's remove() not always deleting on time.

  - by Kyte

  For a particular piece of homework, I'm implementing a basic data storage system using sequential files under standard C, which cannot load more than 1 record at a time. So, the basic part is creating a new file where the results of whatever we do with the original records are stored. The previous file's renamed, and a new one under the working name is created. The code's compiled with MinGW 5.1.6 on Windows 7. Problem is, this particular version of the code (I've got nearly-identical versions of this floating around my functions) doesn't always remove the old file, so the rename fails and hence the stored data gets wiped by the fopen(). FILE *archivo, *antiguo; remove("IndiceNecesidades.old"); // This randomly fails to work in time. rename("IndiceNecesidades.dat", "IndiceNecesidades.old"); // So rename() fails. antiguo = fopen("IndiceNecesidades.old", "rb"); // But apparently it still gets deleted, since this turns out null (and I never find the .old in my working folder after the program's done). archivo = fopen("IndiceNecesidades.dat", "wb"); // And here the data gets wiped. Basically, anytime the .old previously exists, there's a chance it's not removed in time for the rename() to take effect successfully. No possible name conflicts both internally and externally. The weird thing's that it's only with this particular file. Identical snippets except with the name changed to Necesidades.dat (which happen in 3 different functions) work perfectly fine. // I'm yet to see this snippet fail. FILE *antiguo, *archivo; remove("Necesidades.old"); rename("Necesidades.dat", "Necesidades.old"); antiguo = fopen("Necesidades.old", "rb"); archivo = fopen("Necesidades.dat", "wb"); Any ideas on why would this happen, and/or how can I ensure the remove() command has taken effect by the time rename() is executed? (I thought of just using a while loop to force call remove() again so long as fopen() returns a non-null pointer, but that sounds like begging for a crash due to overflowing the OS with delete requests or something.)

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• Odd "Object reference not set to an instance of an object" involving xWinForms

  - by Kyle

  Hey, I've been trying to get the xWinForms 3.0 library (a library with forms support in xna) working with my C# XNA Game project but I keep getting the same problem. I add the reference to my project, put in the using statement, declare a formCollection variable and then I try to initialize it. whenever I run the project I get stopped on this line: formCollection = new FormCollection(this.Window, Services, ref graphics); it gives me the error: " System.NullReferenceException was unhandled Message="Object reference not set to an instance of an object." Source="Microsoft.Xna.Framework" StackTrace: at Microsoft.Xna.Framework.Graphics.VertexShader..ctor(GraphicsDevice graphicsDevice, Byte[] shaderCode) at Microsoft.Xna.Framework.Graphics.SpriteBatch.ConstructPlatformData() at Microsoft.Xna.Framework.Graphics.SpriteBatch..ctor(GraphicsDevice graphicsDevice) at xWinFormsLib.FormCollection..ctor(GameWindow window, IServiceProvider services, GraphicsDeviceManager& graphics) at GameSolution.Game2.LoadContent() in C:\Users\Owner\Documents\School\Year 3\Winter\Soen 390\TeamWTF_3\SourceCode\GameSolution\GameSolution\Game2.cs:line 45 at Microsoft.Xna.Framework.Game.Initialize() at GameSolution.Game2.Initialize() in C:\Users\Owner\Documents\School\Year 3\Winter\Soen 390\TeamWTF_3\SourceCode\GameSolution\GameSolution\Game2.cs:line 37 at Microsoft.Xna.Framework.Game.Run() at GameSolution.Program.Main(String[] args) in C:\Users\Owner\Documents\School\Year 3\Winter\Soen 390\TeamWTF_3\SourceCode\GameSolution\GameSolution\Program.cs:line 14 InnerException: " In a project I downloaded that used the xWinForms, I put the following code in and it compiled and ran no error. but when I put it in my project I get the error. Am I making some stupid mistake about including dlls or something? I've been at this for hours and I can't seem to find anything that would cause this. using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; using Microsoft.Xna.Framework.Net; using Microsoft.Xna.Framework.Storage; using xWinFormsLib; namespace GameSolution { public class Game2 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; FormCollection formCollection; public Game2() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } protected override void Initialize() { // TODO: Add your initialization logic here base.Initialize(); } protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); formCollection = new FormCollection(this.Window, Services, ref graphics); } protected override void Update(GameTime gameTime) { base.Update(gameTime); } protected override void Draw(GameTime gameTime) { base.Draw(gameTime); } } } Any help would be greatly appreciated ._.

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• Searches (and general querying) with HBase and/or Cassandra (best practices?)

  - by alexeypro

  I have User model object with quite few fields (properties, if you wish) in it. Say "firstname", "lastname", "city" and "year-of-birth". Each user also gets "unique id". I want to be able to search by them. How do I do that properly? How to do that at all? My understanding (will work for pretty much any key-value storage -- first goes key, then value) u:123456789 = serialized_json_object ("u" as a simple prefix for user's keys, 123456789 is "unique id"). Now, thinking that I want to be able to search by firstname and lastname, I can save in: f:Steve = u:384734807,u:2398248764,u:23276263 f:Alex = u:12324355,u:121324334 so key is "f" - which is prefix for firstnames, and "Steve" is actual firstname. For "u:Steve" we save as value all user id's who are "Steve's". That makes every search very-very easy. Querying by few fields (properties) -- say by firstname (i.e. "Steve") and lastname (i.e. "l:Anything") is still easy - first get list of user ids from "f:Steve", then list from "l:Anything", find crossing user ids, an here you go. Problems (and there are quite a few): Saving, updating, deleting user is a pain. It has to be atomic and consistent operation. Also, if we have size of value limited to some value - then we are in (potential) trouble. And really not of an answer here. Only zipping the list of user ids? Not too cool, though. What id we want to add new field to search by. Eventually. Say by "city". We certainly can do the same way "c:Los Angeles" = ..., "c:Chicago" = ..., but if we didn't foresee all those "search choices" from the very beginning, then we will have to be able to create some night job or something to go by all existing User records and update those "c:CITY" for them... Quite a big job! Problems with locking. User "u:123" updates his name "Alex", and user "u:456" updates his name "Alex". They both have to update "f:Alex" with their id's. That means either we get into overwriting problem, or one update will wait for another (and imaging if there are many of them?!). What's the best way of doing that? Keeping in mind that I want to search by many fields? P.S. Please, the question is about HBase/Cassandra/NoSQL/Key-Value storages. Please please - no advices to use MySQL and "read about" SELECTs; and worry about scaling problems "later". There is a reason why I asked MY question exactly the way I did. :-)

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• Help choosing authentication method

  - by Dima

  I need to choose an authentication method for an application installed and integrated in customers environment. There are two types of environments - windows and linux/unix. Application is user based, no web stuff, pure Java. The requirement is to authenticate users which will use my application against customer provided user base. Meaning, customer installs my app, but uses his own users to grant or deny access to my app. Typical, right? I have three options to consider and I need to pick up the one which would be a) the most flexible to cover most common modern environments and b) would take least effort while stay robust and standard. Option (1) - Authenticate locally managing user credentials in some local storage, e.g. file. Customer would then add his users to my application and it will then check the passwords. Simple, clumsy but would work. Customers would have to punch every user they want to grant access to my app using some UI we will have to provide. Lots of work for me, headache to the customer. Option (2) - Use LDAP authentication. Customers would tell my app where to look for users and I will walk their directory resolving names into user names and trying to bind with found password. This is better approach IMO, but more fragile because I will have to walk an unknown directory structure and who knows if this will be permitted everywhere. Would be harder to test since there are many LDAP implementation out there, last thing I want is drowning in this voodoo. Option(3) - Use plain Kerberos authentication. Customers would tell my app what realm (domain) and which KDC (key distribution center) to use. In ideal world these two parameters would be all I need to set while customers could use their own administration tools to configure domain and kdc. My application would simply delegate user credentials to this third party (using JAAS or Spring security) and consider success when third party is happy with them. I personally prefer #3, but not sure what surprises I might face. Would this cover windows and *nix systems entirely? Is there another option to consider?

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• Program execution stop at scanf???

  - by Mohit Deshpande

  main.c (with all the headers like stdio, stdlib, etc): int main() { int input; while(1) { printf("\n"); printf("\n1. Add new node"); printf("\n2. Delete existing node"); printf("\n3. Print all data"); printf("\n4. Exit"); printf("Enter your option -> "); scanf("%d", &input); string key = ""; string tempKey = ""; string tempValue = ""; Node newNode; Node temp; switch (input) { case 1: printf("\nEnter a key: "); scanf("%s", tempKey); printf("\nEnter a value: "); scanf("%s", tempValue); //execution ternimates here newNode.key = tempKey; newNode.value = tempValue; AddNode(newNode); break; case 2: printf("\nEnter the key of the node: "); scanf("%s", key); temp = GetNode(key); DeleteNode(temp); break; case 3: printf("\n"); PrintAllNodes(); break; case 4: exit(0); break; default: printf("\nWrong option chosen!\n"); break; } } return 0; } storage.h: #ifndef DATABASEIO_H_ #define DATABASEIO_H_ //typedefs typedef char *string; /* * main struct with key, value, * and pointer to next struct * Also typedefs Node and NodePtr */ typedef struct Node { string key; string value; struct Node *next; } Node, *NodePtr; //Function Prototypes void AddNode(Node node); void DeleteNode(Node node); Node GetNode(string key); void PrintAllNodes(); #endif /* DATABASEIO_H_ */ I am using Eclipse CDT, and when I enter 1, then I enter a key. Then the console says . I used gdb and got this error: Program received signal SIGSEGV, Segmentation fault. 0x00177024 in _IO_vfscanf () from /lib/tls/i686/cmov/libc.so.6 Any ideas why?

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• When is #include <new> library required in C++?

  - by Czarak

  Hi, According to this reference entry for operator new ( http://www.cplusplus.com/reference/std/new/operator%20new/ ) : Global dynamic storage operator functions are special in the standard library: All three versions of operator new are declared in the global namespace, not in the std namespace. The first and second versions are implicitly declared in every translation unit of a C++ program: The header does not need to be included for them to be present. This seems to me to imply that the third version of operator new (placement new) is not implicitly declared in every translation unit of a C++ program and the header <new> does need to be included for it to be present. Is that correct? If so, how is it that using both g++ and MS VC++ Express compilers it seems I can compile code using the third version of new without #include <new> in my source code? Also, the MSDN Standard C++ Library reference entry on operator new gives some example code for the three forms of operator new which contains the #include <new> statement, however the example seems to compile and run just the same for me without this include? // new_op_new.cpp // compile with: /EHsc #include<new> #include<iostream> using namespace std; class MyClass { public: MyClass( ) { cout << "Construction MyClass." << this << endl; }; ~MyClass( ) { imember = 0; cout << "Destructing MyClass." << this << endl; }; int imember; }; int main( ) { // The first form of new delete MyClass* fPtr = new MyClass; delete fPtr; // The second form of new delete char x[sizeof( MyClass )]; MyClass* fPtr2 = new( &x[0] ) MyClass; fPtr2 -> ~MyClass(); cout << "The address of x[0] is : " << ( void* )&x[0] << endl; // The third form of new delete MyClass* fPtr3 = new( nothrow ) MyClass; delete fPtr3; } Could anyone shed some light on this and when and why you might need to #include <new> - maybe some example code that will not compile without #include <new> ? Thanks.

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• MSBuild condition across projects

  - by Billy Talented

  I have tried several solutions for this problem. Enough to know I do not know enough about MSBuild to do this elegantly but I feel like there should be a method. I have a set of libraries for working with .net projects. A few of the projects utilize System.Web.Mvc - which recently released Version 2 - and we are looking forward to the upgrade. Currently sites which reference this library reference it directly by the project(csproj) on the developer's computer - not a built version of the library so that changes and source code case easily be viewed when dealing code from this library. This works quite well and would prefer to not have to switch to binary references (but will if this is the only solution). The problem I have is that because of some of the functionality that was added onto the MVC1 based library (view engines, model binders etc) several of the sites reliant on these libraries need to stay on MVC1 until we have full evaluated and tested them on MVC2. I would prefer to not have to fork or have two copies on each dev machine. So what I would like to be able to do is set a property group value in the referencing web application and have this read by the above mentions library with the caviat that when working directly on the library via its containing solution I would like to be able to control this via Configuration Manager by selecting a build type and that property overriding the build behavior of the solution (i.e. 'Debug - MVC1' vs 'Debug -MVC2') - I have this working via: <Choose> <When Condition=" '$(Configuration)|$(Platform)' == 'Release - MVC2|AnyCPU' Or '$(Configuration)|$(Platform)' == 'Debug - MVC2|AnyCPU'"> <ItemGroup> <Reference Include="System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL"> </Reference> <Reference Include="Microsoft.Web.Mvc, Version=1.0.0.0, Culture=neutral, processorArchitecture=MSIL"> <SpecificVersion>False</SpecificVersion> <HintPath>..\Dependancies\Web\MVC2\Microsoft.Web.Mvc.dll</HintPath> </Reference> </ItemGroup> </When> <Otherwise> <ItemGroup> <Reference Include="System.Web.Mvc, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL"> <SpecificVersion>False</SpecificVersion> <HintPath>..\Dependancies\Web\MVC\System.Web.Mvc.dll</HintPath> </Reference> </ItemGroup> </Otherwise> The item that I am struggling with is the cross solution issue(solution TheWebsite references this project and needs to control which build property to use) that I have not found a way to work with that I think is a solid solution that enabled the build within visual studio to work as it has to date. Other bits: we are using VS2008, Resharper, TeamCity for CI, SVN for source control.

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• android zxing intentintegrator

  - by cristi _b

  I've written the following code that works fine if you decide to scan a QR code (using zxing) and store it in private storage but in case you decide to cancel scanning, it crashes and the file previously stored content disappears. I think it might be a design error, not sure why. Below is relevant code ... /** * menu generation */ @Override public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.menu, menu); return true; } /** * menu handling */ @Override public boolean onOptionsItemSelected(MenuItem item) { Context context = getApplicationContext(); Toast toast = Toast.makeText(context, "", Toast.LENGTH_LONG); toast.setGravity(Gravity.FILL_HORIZONTAL, 0, 0); switch (item.getItemId()) { case R.id.qrScan: IntentIntegrator integrator = new IntentIntegrator(this); integrator.initiateScan(); return true; case R.id.qrReset: File dir = getFilesDir(); File file = new File(dir, qrCodeFile); boolean deleted = file.delete(); return true; case R.id.appClose: this.finish(); return true; default: return super.onOptionsItemSelected(item); } } ... public void onActivityResult(int requestCode, int resultCode, Intent intent) { IntentResult scanResult = IntentIntegrator.parseActivityResult(requestCode, resultCode, intent); Context context = getApplicationContext(); Toast toast = Toast.makeText(context, "", Toast.LENGTH_SHORT); if (scanResult != null) { FileOutputStream fos = null; CharSequence text = scanResult.getContents(); try { fos = openFileOutput(qrCodeFile, Context.MODE_PRIVATE); try { fos.write(text.toString().getBytes()); fos.close(); toast.setGravity(Gravity.FILL_HORIZONTAL, 0, 0); toast.setText("Code saved"); toast.show(); } catch (IOException ex) { toast.setGravity(Gravity.FILL_HORIZONTAL, 0, 0); toast.setText("Invalid code"); toast.show(); Logger.getLogger(MainActivity.class.getName()).log(Level.SEVERE, null, ex); } } catch (FileNotFoundException ex) { toast.setGravity(Gravity.FILL_HORIZONTAL, 0, 0); toast.setText("Error while saving"); toast.show(); Logger.getLogger(MainActivity.class.getName()).log(Level.SEVERE, null, ex); } } else { toast.setGravity(Gravity.FILL_HORIZONTAL, 0, 0); toast.setText("Invalid code"); toast.show(); } }

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• What do I need to write a small game on Linux?

  - by Michas

  I want to make a simple game: 2d, single-player, without tons of animations and special effects. I am not interested in ready to use game engines, I want to learn to write some code in a quite universal language. I am using Linux (AMD64) and looking for something easy with nice library for games. I do not want to mix few languages, most of them are in fact fast enough themselves for my needs. Cross platform would be an advantage, however all I need is a good Linux support. I have been considering few solutions. Ruby + Language looks very nice. + I am going to learn Ruby. - I am afraid I can have problems with additional libraries. - This thread about game libraries for Ruby could be longer. SDL + C + It is used for games. + It is very easy to set up. + There is a lot of additional libraries. + It is cross-platform. - The solution is quite low level. - The language is sometimes quite hard to read. QT + C++ + It is very easy to set up. + The standard QT libraries supports everything I can possibly need. + It is cross-platform. + The documentation is good. - The compilation is slow. - The language looks horrible. - The size of standard QT libraries is too big to comprehend. Environment of web browser + I am going to learn something more about this environment. + It is somewhat used for games. + It is quite cross-platform. - It would be too much experimental. Java + It is used for games. + The standard Java libraries supports everything I can possibly need. + It is cross-platform. - It is quite hard to set up. - The size of standard Java libraries is too big to comprehend. - The source code in Java could look better. - I think I do not want to learn Java. Google Go + I am going to learn Google Go. - There is big problem with libraries. - The solution would be quite low level. Python + It looks some people do games in Python, according to this thread. + It looks there are probably more libraries than for Ruby. - The Ruby language looks better. - I think I do not want to learn Python. C++ + something else + It is used for games. + It would be probably cross-platform. + There is a lot of libraries. - I do not need C++ extensions over C. - Compilation could be slow, there are fast compilers for C, not for C++. Haskell + I am going to learn Haskell. - Many things about programming computer games looks too much imperative. - It looks I can have some problems with libraries. - Compilation (GHC) looks slow. There is probably something more to consider. Does anyone have experience in making small games for Linux in non mainstream solutions? Does anyone have an advice for me?

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• Recursive N-way merge/diff algorithm for directory trees?

  - by BobMcGee

  What algorithms or Java libraries are available to do N-way, recursive diff/merge of directories? I need to be able to generate a list of folder trees that have many identical files, and have subdirectories with many similar files. I want to be able to use 2-way merge operations to quickly remove as much redundancy as possible. Goals: Find pairs of directories that have many similar files between them. Generate short list of directory pairs that can be synchronized with 2-way merge to eliminate duplicates Should operate recursively (there may be nested duplicates of higher-level directories) Run time and storage should be O(n log n) in numbers of directories and files Should be able to use an embedded DB or page to disk for processing more files than fit in memory (100,000+). Optional: generate an ancestry and change-set between folders Optional: sort the merge operations by how many duplicates they can elliminate I know how to use hashes to find duplicate files in roughly O(n) space, but I'm at a loss for how to go from this to finding partially overlapping sets between folders and their children. EDIT: some clarification The tricky part is the difference between "exact same" contents (otherwise hashing file hashes would work) and "similar" (which will not). Basically, I want to feed this algorithm at a set of directories and have it return a set of 2-way merge operations I can perform in order to reduce duplicates as much as possible with as few conflicts possible. It's effectively constructing an ancestry tree showing which folders are derived from each other. The end goal is to let me incorporate a bunch of different folders into one common tree. For example, I may have a folder holding programming projects, and then copy some of its contents to another computer to work on it. Then I might back up and intermediate version to flash drive. Except I may have 8 or 10 different versions, with slightly different organizational structures or folder names. I need to be able to merge them one step at a time, so I can chose how to incorporate changes at each step of the way. This is actually more or less what I intend to do with my utility (bring together a bunch of scattered backups from different points in time). I figure if I can do it right I may as well release it as a small open source util. I think the same tricks might be useful for comparing XML trees though.

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• Why is cell phone software still so primitive?

  - by Tomislav Nakic-Alfirevic

  I don't do mobile development, but it strikes me as odd that features like this aren't available by default on most phones: full text search: searches all address book contents, messages, anything else being a plus better call management: e.g. a rotating audio call log, meaning you always have the last N calls recorded for your listening pleasure later (your little girl just said her first "da-da" while you were on a business trip, you had a telephone job interview, you received complex instructions to do something etc.) bluetooth remote control (like e.g. anyRemote, but available by default on a bluetooth phone) no multitasking capabilities worth mentioning and in general no e.g. weekly software updates, making the phone much more usable (even if it had to be done over USB, rather than over the network). I'm sure I was dumbfounded by the lack or design of other features as well, but they don't come to mind right now. To clarify, I'm not talking about smartphones here: my plain, 2-year old phone has a CPU an order of magnitude faster than my first PC, about as much storage space and it's ridiculous how bad (slow, unwieldy) the software is and it's not one phone or one manufacturer. What keeps the (to me) obvious software functionality vacuum on a capable hardware platform from being filled up? Edit: I believe a clarification on the multitasking point might be beneficial. I'll use my phone as an example, although the point is much more general. The phone can multitask and in fact does: you can listen to music and do something else at the same time. On the other hand, the way the software has been designed makes multitasking next to useless. (Ditto with the external touch screen: it can take touch commands, but only one application makes use of it, and only with 3 commands.) To take the multitasking example to the extreme, if I plug my phone into my laptop and it registers as an external disk, it doesn't allow any kind of operation: messages, calling, calendar, everything out of reach, although I can receive a call. No "battery life" issue there: it's charging while connected. BTW, another example of design below the current state of the art: I don't see a phone on the horizon which will remember where in an audio or video file you were when you stopped listening/watching it last time (podcasts are a good use case). Simplistic rewind/fast forward functionality only aggravates the problem.

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• How to implement Xml Serialization with inherited classes in C#

  - by liorafar

  I have two classes : base class name Component and inheritd class named DBComponent [Serializable] public class Component { private string name = string.Empty; private string description = string.Empty; } [Serializable] public class DBComponent : Component { private List<string> spFiles = new List<string>(); // Storage Procedure Files [XmlArrayItem("SPFile", typeof(string))] [XmlArray("SPFiles")] public List<string> SPFiles { get { return spFiles; } set { spFiles = value; } } public DBComponent(string name, string description) : base(name, description) { } } [Serializable] public class ComponentsCollection { private static ComponentsCollection instance = null; private List<Component> components = new List<Component>(); public List<Component> Components { get { return components; } set { components = value; } } public static ComponentsCollection GetInstance() { if (ccuInstance == null) { lock (lockObject) { if (instance == null) PopulateComponents(); } } return instance; } private static void PopulateComponents() { instance = new CCUniverse(); XmlSerializer xs = new XmlSerializer(instance.GetType()); instance = xs.Deserialize(XmlReader.Create("Components.xml")) as ComponentsCollection; } } } I want read\write from a Xml file. I know that I need to implement the Serialization for DBComponent class otherwise it will not read it.But i cannot find any simple article for that. all the articles that I found were too complex for this simple scenario. The Xml file looks like this: <?xml version="1.0" encoding="utf-8" ?> <ComponentsCollection> <Components> <DBComponent Name="Tenant Historical Database" Description="Tenant Historical Database"> <SPFiles> <SPFile>Setup\TenantHistoricalSP.sql</SPFile> </SPFiles> </DBComponent> <Component Name="Agent" Description="Desktop Agent" /> </Components> </ComponentsCollection> Can someone please give me a simple example of how to read this kind of xml file and what should be implemented ? Thanks Lior

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• Pass MSBuild condition to library project

  - by Billy Talented

  I have tried several solutions for this problem. Enough to know I do not know enough about MSBuild to do this elegantly but I feel like there should be a method. I have a set of libraries for working with .net projects. A few of the projects utilize System.Web.Mvc - which recently released Version 2 - and we are looking forward to the upgrade. Currently sites which reference this library reference it directly by the project(csproj) on the developer's computer - not a built version of the library so that changes and source code case easily be viewed when dealing code from this library. This works quite well and would prefer to not have to switch to binary references (but will if this is the only solution). The problem I have is that because of some of the functionality that was added onto the MVC1 based library (view engines, model binders etc) several of the sites reliant on these libraries need to stay on MVC1 until we have full evaluated and tested them on MVC2. I would prefer to not have to fork or have two copies on each dev machine. So what I would like to be able to do is set a property group value in the referencing web application and have this read by the above mentions library with the caviat that when working directly on the library via its containing solution I would like to be able to control this via Configuration Manager by selecting a build type and that property overriding the build behavior of the solution (i.e. 'Debug - MVC1' vs 'Debug -MVC2') - I have this working via: <Choose> <When Condition=" '$(Configuration)|$(Platform)' == 'Release - MVC2|AnyCPU' Or '$(Configuration)|$(Platform)' == 'Debug - MVC2|AnyCPU'"> <ItemGroup> <Reference Include="System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL"> </Reference> <Reference Include="Microsoft.Web.Mvc, Version=1.0.0.0, Culture=neutral, processorArchitecture=MSIL"> <SpecificVersion>False</SpecificVersion> <HintPath>..\Dependancies\Web\MVC2\Microsoft.Web.Mvc.dll</HintPath> </Reference> </ItemGroup> </When> <Otherwise> <ItemGroup> <Reference Include="System.Web.Mvc, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL"> <SpecificVersion>False</SpecificVersion> <HintPath>..\Dependancies\Web\MVC\System.Web.Mvc.dll</HintPath> </Reference> </ItemGroup> </Otherwise> The item that I am struggling with is the cross solution issue(solution TheWebsite references this project and needs to control which build property to use) that I have not found a way to work with that I think is a solid solution that enabled the build within visual studio to work as it has to date. Other bits: we are using VS2008, Resharper, TeamCity for CI, SVN for source control.

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• What does the `forall` keyword in Haskell/GHC do?

  - by JUST MY correct OPINION

  I've been banging my head on this one for (quite literally) years now. I'm beginning to kinda/sorta understand how the foreach keyword is used in so-called "existential types" like this: data ShowBox = forall s. Show s => SB s (This despite the confusingly-worded explanations of it in the fragments found all around the web.) This is only a subset, however, of how foreach is used and I simply cannot wrap my mind around its use in things like this: runST :: forall a. (forall s. ST s a) -> a Or explaining why these are different: foo :: (forall a. a -> a) -> (Char,Bool) bar :: forall a. ((a -> a) -> (Char, Bool)) Or the whole RankNTypes stuff that breaks my brain when "explained" in a way that makes me want to do that Samuel L. Jackson thing from Pulp Fiction. (Don't follow that link if you're easily offended by strong language.) The problem, really, is that I'm a dullard. I can't fathom the chicken scratchings (some call them "formulae") of the elite mathematicians that created this language seeing as my university years are over two decades behind me and I never actually had to put what I learnt into use in practice. I also tend to prefer clear, jargon-free English rather than the kinds of language which are normal in academic environments. Most of the explanations I attempt to read on this (the ones I can find through search engines) have these problems: They're incomplete. They explain one part of the use of this keyword (like "existential types") which makes me feel happy until I read code that uses it in a completely different way (like runST, foo and bar above). They're densely packed with assumptions that I've read the latest in whatever branch of discrete math, category theory or abstract algebra is popular this week. (If I never read the words "consult the paper whatever for details of implementation" again, it will be too soon.) They're written in ways that frequently turn even simple concepts into tortuously twisted and fractured grammar and semantics. (I suspect that the last two items are the biggest problem. I wouldn't know, though, since I'm too much a dullard to comprehend them.) It's been asked why Haskell never really caught on in industry. I suspect, in my own humble, unintelligent way, that my experience in figuring out one stupid little keyword -- a keyword that is increasingly ubiquitous in the libraries being written these days -- are also part of the answer to that question. It's hard for a language to catch on when even its individual keywords cause years-long quests to comprehend. Years-long quests which end in failure. So... On to the actual question. Can anybody completely explain the foreach keyword in clear, plain English (or, if it exists somewhere, point to such a clear explanation which I've missed) that doesn't assume I'm a mathematician steeped in the jargon?

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