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• Feasibility of using Silverlight for web and windows client with common code base for data intensive

  - by Kabeer

  Hello. Recently in a conversation, someone suggested me to make use of Silverlight if I am targeting a web client and a windows client for the same application. This will cut down my effort for supporting the contrast in both presentation layers. Mine is a product, that will be deployed in enterprises. Both web and windows clients are desirable. With the above context, I have few queries: Is it advisable to adopt the recommended approach and whether this approach is becoming a trend? Besides, some configuration & deployment tweaking, will this significantly reduce effort on the presentation layer? Is there a possibility that my future prospects (for this product) will resist Silverlight footprint? Will I be able to make use of the ASP.Net MVC pattern? Will there be any performance implication for the web client? Will Silverlight support incremental load of controls? If my back-end includes SSRS, will I be able to harness all its front end features with Silverlight? Will I be able to support additional devices with same code base in future? Mine is a very data intensive application from both, data entry and reporting perspective. Is it advisable to use 3rd party controls (like Telerik) for improved user experience and developer productivity? Are their any professional quality open source Silverlight controls (library) available? Further, I seek information of best practices in the context I shared above.

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• Advice on optimzing speed for a Stored Procedure that uses Views

  - by Belliez

  Based on a previous question and with a lot of help from Damir Sudarevic (thanks) I have the following sql code which works great but is very slow. Can anyone suggest how I can speed this up and optimise for speed. I am now using SQL Server Express 2008 (not 2005 as per my original question). What this code does is retrieves parameters and their associated values from several tables and rotates the table in a form that can be easily compared. Its great for one of two rows of data but now I am testing with 100 rows and to run GetJobParameters takes over 7 minutes to complete? Any advice is gratefully accepted, thank you in advanced. /*********************************************************************************************** ** CREATE A VIEW (VIRTUAL TABLE) TO ALLOW EASIER RETREIVAL OF PARMETERS ************************************************************************************************/ CREATE VIEW dbo.vParameters AS SELECT m.MachineID AS [Machine ID] ,j.JobID AS [Job ID] ,p.ParamID AS [Param ID] ,t.ParamTypeID AS [Param Type ID] ,m.Name AS [Machine Name] ,j.Name AS [Job Name] ,t.Name AS [Param Type Name] ,t.JobDataType AS [Job DataType] ,x.Value AS [Measurement Value] ,x.Unit AS [Unit] ,y.Value AS [JobDataType] FROM dbo.Machines AS m JOIN dbo.JobFiles AS j ON j.MachineID = m.MachineID JOIN dbo.JobParams AS p ON p.JobFileID = j.JobID JOIN dbo.JobParamType AS t ON t.ParamTypeID = p.ParamTypeID LEFT JOIN dbo.JobMeasurement AS x ON x.ParamID = p.ParamID LEFT JOIN dbo.JobTrait AS y ON y.ParamID = p.ParamID GO -- Step 2 CREATE VIEW dbo.vJobValues AS SELECT [Job Name] ,[Param Type Name] ,COALESCE(cast([Measurement Value] AS varchar(50)), [JobDataType]) AS [Val] FROM dbo.vParameters GO /*********************************************************************************************** ** GET JOB PARMETERS FROM THE VIEW JUST CREATED ************************************************************************************************/ CREATE PROCEDURE GetJobParameters AS -- Step 3 DECLARE @Params TABLE ( id int IDENTITY (1,1) ,ParamName varchar(50) ); INSERT INTO @Params (ParamName) SELECT DISTINCT [Name] FROM dbo.JobParamType -- Step 4 DECLARE @qw TABLE( id int IDENTITY (1,1) , txt nchar(300) ) INSERT INTO @qw (txt) SELECT 'SELECT' UNION SELECT '[Job Name]' ; INSERT INTO @qw (txt) SELECT ',MAX(CASE [Param Type Name] WHEN ''' + ParamName + ''' THEN Val ELSE NULL END) AS [' + ParamName + ']' FROM @Params ORDER BY id; INSERT INTO @qw (txt) SELECT 'FROM dbo.vJobValues' UNION SELECT 'GROUP BY [Job Name]' UNION SELECT 'ORDER BY [Job Name]'; -- Step 5 --SELECT txt FROM @qw DECLARE @sql_output VARCHAR (MAX) SET @sql_output = '' -- NULL + '' = NULL, so we need to have a seed SELECT @sql_output = -- string to avoid losing the first line. COALESCE (@sql_output + txt + char (10), '') FROM @qw EXEC (@sql_output) GO

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• RESTful idempotence

  - by DutrowLLC

  I'm designing a RESTful web service utilizing ROA(Resource oriented architecture). I'm trying to work out an efficient way to guarantee idempotence for PUT requests that create new resources in cases that the server designates the resource key. From my understanding, the traditional approach is to create a type of transaction resource such as /CREATE_PERSON. The the client-server interaction for creating a new person resource would be in two parts: Step 1: Get unique transaction id for creating the new PERSON resource::: **Client request:** GET /CREATE_PERSON **Server response:** 200 OK transaction-id:"as8yfasiob" Step 2: Create the new person resource in a request guaranteed to be unique by using the transaction id::: **Client request** PUT /CREATE_PERSON/{transaction_id} first_name="Big bubba" **Server response** 201 Created // (If the request is a duplicate, it would send this PersonKey="398u4nsdf" // same response without creating a new resource. It // would perhaps send an error response if the was used // on a transaction id non-duplicate request, but I have // control over the client, so I can guarantee that this // won't happen) The problem that I see with this approach is that it requires sending two requests to the server in order to do to single operation of creating a new PERSON resource. This creates a performance issues increasing the chance that the user will be waiting around for the client to complete their request. I've been trying to hash out ideas for eliminating the first step such as pre-sending transaction-id's with each request, but most of my ideas have other issues or involve sacrificing the statelessness of the application. Is there a way to do this?

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• WCF 3.5 - Remove SVC Extension - Special Case

  - by Brandon

  I have several RESTful endpoints like such: System.Security.Role.svc System.Security.User.svc etc. This is meant to be a namespace so our RESTful URL's would look like: /rest/{class namespace}/{actions} I have tried a few examples to get the SVC extension removed when my endpoint has multiple periods in it, however, nothing seems to work. I have tested with the WCF REST Contrib package (http://wcfrestcontrib.codeplex.com/), this example (http://www.west-wind.com/weblog/posts/570695.aspx), and another StackOverflow post (http://stackoverflow.com/questions/355165/how-to-remove-thie-svc-extension-in-restful-wcf-service). This works great when my endpoint is something like this: Echo.svc It will properly remove the SVC extension. Any ideas on how to handle endpoints with multiple periods in the endpoint name? EDIT: After some further testing, I found out that it is failing because whenever you do: string path = HttpContext.Current.Request.AppRelativeCurrentExecutionFilePath; If the endpoint contains multiple periods, it strips off everything after the endpoint causing all of the standard IHttpModule's to fail. Example: If I call http://localhost/services/Echo/test, my relative app file path has a returned value of: ~/echo/test However, if I make a call as http://localhost/services/System.Security.User/test, then my relative app file path has a returned value of: ~/system.security.user I am missing the '/test' on the end in that situation.

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• Passenger: "Missing these required gems redgreen"

  - by Michael Stum

  Hello, total ruby newbie, trying to setup a Rails/MongoDB application on Mac OS X Snow leopard. Installed Ruby 1.9.1 and RubyGems 1.3.7, which ruby and which gem point to the same directory. I'm using the Snow Leopard built-in apache and Passenger 2.2.11. I'm using the rails template from the mongo-site which seems to work okay overall. The exact error that passenger gives me is: /Users/User/Sites/feuerapp/vendor/rails/railties/lib/rails/gem_dependency.rb:119:Warning: Gem::Dependency#version_requirements is deprecated and will be removed on or after August 2010. Use #requirement **Notice: C extension not loaded. This is required for optimum MongoDB Ruby driver performance. You can install the extension as follows: gem install bson_ext If you continue to receive this message after installing, make sure that the bson_ext gem is in your load path and that the bson_ext and mongo gems are of the same version. Missing these required gems: redgreen You're running: ruby 1.9.1.376 at /usr/local/bin/ruby rubygems 1.3.7 at /Users/User/.gem/ruby/1.9.1, /usr/local/lib/ruby/gems/1.9.1 Runrake gems:installto install the missing gems. The weird thing is that redgreen is installed and looks fine to me: Dahlia:feuerapp User$ ls -la vendor/gems/ total 0 drwxr-xr-x 7 User staff 238 May 18 22:56 . drwxr-xr-x 5 User staff 170 May 18 23:00 .. drwxr-xr-x 11 User staff 374 May 18 22:56 factory_girl-1.2.4 drwxr-xr-x 11 User staff 374 May 18 22:56 mocha-0.9.8 drwxr-xr-x 7 User staff 238 May 18 22:56 mongo_mapper-0.7.6 drwxr-xr-x 7 User staff 238 May 18 22:56 redgreen-1.2.2 drwxr-xr-x 11 User staff 374 May 18 22:56 shoulda-2.10.3 Commenting out this line in environment.rb "solves" the issue, but that's not really want I want: config.gem 'redgreen' I don't understand anything of gems yet, but from my limited understanding, redgreen should be there and found?

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• PHP Frameworks: Codeigniter vs. Yii vs. Custom?

  - by Industrial

  Hi everybody, I have used codeigniter for a some years now. Why I chosed to work with codeigniter back then? Pretty much for the extensive documentation that were available and the big user community. It made me as a totally newbie to the MVC pattern able to get a site up and running really fast. I think what is priorited from my side is that the framework doesn't affect performance too much, which Codeigniter seems to be pretty good at (when compared to other frameworks out there) and Yii, an even better option. Since the time has gone from when I started out with codeigniter, the project sizes have also increased and thereby the demand of the framework and it's footprint on the code. I have thought a few times about writing a whole new MVC framework to do only the thing's I want it to do, but it feels like reinventing the wheel and I cannot yet justify it. I am not sure whether or not it's a good solution to build a site that have the potential to become really big on either Yii or Codeigniter. I have tried to find as much as possible documentation about this comparision/issue online before posting here, but have found very few real-life arguments and stories from people that have shifted between the two PHP frameworks or have been in the same situation as me. So - what's your thoughts about Codeigniter vs. Yii vs. going custom? References: http://daniel.carrera.bz/2009/01/comparison-of-php-frameworks-part-i/ http://www.beyondcoding.com/2009/03/02/choosing-a-php-framework-round-2-yii-vs-kohana-vs-codeigniter/

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• Contributing to a Linux distribution

  - by Big Al

  I'm interested in contributing to a Linux distro, but regarding the various distro's developer communities, I'm having a bit of trouble figuring out which one I'd most like to join. What languages I know: C, C++, Lua, Python, and fairly familiar with Perl (though I wouldn't say I "know" it). In particular, I have very little experience with x86 assembly besides hacking stuff together for performance tweaks, though that will be partially rectified soon. What I'm looking for: A community that provides plenty of opportunities for developers to work on various aspects of the distribution. To be honest I'm most interested in reading and working on the kernel source (in which case the distro doesn't matter), but it's pretty daunting and I figure getting into the Linux community and working with experienced Linux developers might give me a better idea of how to jump into the guts(let me know if this is bogus, or if you have any advice regarding that). So... Which distro has the "best" developer community in terms of organization, people who are fun to work with, and opportunities to contribute? I've read various "Contributing to XXX" pages and mailing lists for distros like Ubuntu, OpenSuse, Fedora, etc. but I'd rather get a more personal testament from an actual developer.

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• How to make a GRANT persist for a table that's being dropped and re-created?

  - by Eli Courtwright

  I'm on a fairly new project where we're still modifying the design of our Oracle 11g database tables. As such, we drop and re-create our tables fairly often to make sure that our table creation scripts work as expected whenever we make a change. Our database consists of 2 schemas. One schema has some tables with INSERT triggers which cause the data to sometimes be copied into tables in our second schema. This requires us to log into the database with an admin account such as sysdba and GRANT access to the first schema to the necessary tables on the second schema, e.g. GRANT ALL ON schema_two.SomeTable TO schema_one; Our problem is that every time we make a change to our database design and want to drop and re-create our database tables, the access we GRANT-ed to schema_one went away when the table was dropped. Thus, this creates another annoying step wherein we must log in with an admin account to re-GRANT the access every time one of these tables is dropped and re-created. This isn't a huge deal, but I'd love to eliminate as many steps as possible from our development and testing procedures. Is there any way to GRANT access to a table in such a way that the GRANT-ed permissions survive a table being dropped and then re-created? And if this isn't possible, then is there a better way to go about this?

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• Best way to manipulate and compare strings

  - by vtortola

  I'm developing a REST service, so a request could be something like this: /Data/Main/Table=Customers/ I need to get the segments one by one, and for each segment I will decide wich object I'm going to use, after I'll pass to that object the rest of the query so it can decide what to do next. Basically, the REST query is a path on a tree :P This imply lots String operations (depending on the query complexity), but StringBuilder is useful just for concatenations and remove, you cannot perform a search with IndexOf or similar. I've developed this class that fulfill my requirement, but the problem is that is manipulating Strings, so every time I get one segment ... I'll create extra Strings because String is an inmutable data type: public class RESTQueryParser { String _query; public RESTQueryParser(String query) { _query = query; } public String GetNext() { String result = String.Empty; Int32 startPosition = _query.StartsWith("/", StringComparison.InvariantCultureIgnoreCase) ? 1 : 0; Int32 i = _query.IndexOf("/", startPosition, StringComparison.InvariantCultureIgnoreCase) - 1; if (!String.IsNullOrEmpty(_query)) { if (i < 0) { result = _query.Substring(startPosition, _query.Length - 1); _query = String.Empty; } else { result = _query.Substring(startPosition, i); _query = _query.Remove(0, i + 1); } } return result; } } The server should support a lot of calls, and the queries could be huge, so this is gonna be a very repetitive task. I don't really know how big is the impact on the memory and the performance, I've just readed about it in some books. Should I implement a class that manage a Char[] instead Strings and implement the methods that I want? Or should be ok with this one? Regular expressions maybe?

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• "Programming In Haskell" error in sat function

  - by Matt Ellen

  I'm in chapter 8 of Graham Hutton's Programming in Haskell and I'm copying the code and testing it in GHC. See the slides here: http://www.cis.syr.edu/~sueo/cis352/chapter8.pdf in particular slide 15 The relevant code I've copied so far is: type Parser a = String -> [(a, String)] pih_return :: a -> Parser a pih_return v = \inp -> [(v, inp)] failure :: Parser a failure = \inp -> [] item :: Parser Char item = \inp -> case inp of [] -> [] (x:xs) -> [(x,xs)] parse :: Parser a -> String -> [(a, String)] parse p inp = p inp sat :: (Char -> Bool) -> Parser Char sat p = do x <- item if p x then pih_return x else failure I have changed the name of the return function from the book to pih_return so that it doesn't clash with the Prelude return function. The errors are in the last function sat. I have copied this directly from the book. As you can probably see p is a function from Char to Bool (e.g. isDigit) and x is of type [(Char, String)], so that's the first error. Then pih_return takes a value v and returns [(v, inp)] where inp is a String. This causes an error in sat because the v being passed is x which is not a Char. I have come up with this solution, by explicitly including inp into sat sat :: (Char -> Bool) -> Parser Char sat p inp = do x <- item inp if p (fst x) then pih_return (fst x) inp else failure inp Is this the best way to solve the issue?

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• Flash movies in inactive browser tabs pause or don't execute in real time

  - by ZenBlender

  I'm noticing some unexpected behavior. Some time in the last few months, a change in either Firefox, the Flash player, or both, has made it so that Flash movies that are in inactive browser tabs no longer execute in real time. They appear to still execute, but only in bursts, and not in a predictable way. This is a problem because I develop a Flash-based (Actionscript 2.0, Flash CS3) multiplayer game that maintains a network connection and allows players to chat, etc. Many of our players complain about Firefox crashing while playing the game. I have noticed it too, not too frequently, but it crashes several times a week. (Firefox crashes, I do not get a message from Flash player that indicates an infinite loop or problem in my code) My theory is that this new behavior is causing crashes when there is a lot of activity in my game, leading to lots of unhandled network traffic for my game getting buffered before Firefox/Flash will give it a chance to execute. Maybe this leads to a buffer overflow or missing packets, and as a result, something crashes. At times I will switch back to the tab that is running my game and discover a display bug, which looks as though Flash has simply failed to execute something that it was supposed to. I would assume this new behavior is on purpose, for example to prevent all the Flash-based advertisements in inactive tabs from executing and therefore killing performance. In a quick test on Chrome (5.0.342.9 beta), this "pausing" of Flash seems to be there as well, but somehow it seems much less of a problem. My users have only complained about Firefox crashing, not other browsers. My machine: Windows 7 x64 Firefox 3.6.3 Flash Player 10.1.50.426 My game: triplejack.com Any ideas? Ideally I'd like to disable this behavior for my Flash game so it can execute in real time even when in an inactive tab. Thanks for any help!

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• Jquery star rating plugin and cancel rating button

  - by Roger

  Using this plugin: http://www.fyneworks.com/jquery/star-rating/#tab-Testing I have a simple callback function that picks up the id from the radio buttons: <input type="radio" class="auto-submit-star {split:2}" id="myid" value="1" /> $('.auto-submit-star').rating({ callback: function(value, link){ alert($(this).attr('id')); } }); This works fine, but if the user clicks on the cancel button, then it can't read the id of it. In the js, I think the cancel button is added dynamically with: control.cancel = $('<div class="rating-cancel"><a title="' + control.cancel + '">' + control.cancelValue + '</a></div>') If I add an id to it like this: control.cancel = $('<div class="rating-cancel"><a id="someid" title="' + control.cancel + '">' + control.cancelValue + '</a></div>') How could I read the id? This would be undefined. I can set a class and use $('.myclass').attr('id') but I will have multiple ratings on one page so I'll need something similar to "this". Or is it possible for the cancel button to pick up the id of the corresponding radio buttons?

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• Galleria and Infinite carousel and ajax

  - by John the horn

  Hy all you smart people I am using Galleria plugin for a image gallery on a page this page is loaded in a frame page using ajax this is the ajax $(document).ready(function() { function loadTab(pageUrl) { $.ajax( { url: pageUrl, cache: true, success: function(load) { $("#tabcontent").empty().append(load); } }); } $(document).ready(function() { $("#tab1").ready(function() { loadTab("acasa.html"); }); $("#tab1").click(function() { loadTab("acasa.html"); }); $("#tab2").click(function() { loadTab("desprenoi.html"); }); $("#tab3").click(function() { loadTab("servici.html"); }); $("#tab4").click(function() { loadTab("parteneri.html"); }); $("#tab5").click(function() { loadTab("galerie.html"); }); $("#tab6").click(function() { loadTab("contact.php"); }); }); }); On the frame page Im using Infinite gallery that uses <ul></ul> tags my problem is that offline, testing the page it works perfect but on the server(online) the gallery using galleria goes to the dogs. What I mean is that I have in stead of the gallery the a list of all the images. Can enione help this pore nube ? Thx for your time. P.S. Can enyone help me find a better ajax script :D

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• java distributed cache for low latency, high availability

  - by Shahbaz

  I've never used distributed caches/DHTs like memcached, jboss cache, ehcache, etc. I'm wondering which, if any, is appropriate for my use. First, I'm not doing web applications (as most of these project seem to be geared towards web apps). I write servers (Order Management Systems actually) for financial trading firms. The servers themselves are not too complicated. They need to receive information (market data, orders, executions, etc.) rout them to their destination while possibly transforming some of these messages. I am looking at these products to solve the following problems: * Safe repository of the state of the server. I'd rather build the logic of my application as a bunch of transformers (similar to Apache Camel) and store the state in a 'safe' place * This repository should be distributed: in case one of these data stores crashes, one or two more should be up and I should be able to switch to them seamlessly * This repository should be fast. Single digits milliseconds count here, in other words, systems which consume/process this data are automated systems, not humans clicking on links. This system needs to have high-throughput and low latency. By sending my data outside the process, I am necessarily slowing performance, but I am trying to balance absolute raw speed and absolute protection of data. * This repository should be safe. Similar to the point about several on-line backups, this system needs to write data to disk (potentially more than one disk). I'd really like to stop writing my own 'transaction servers.' Am I correct to be looking into projects such as jboss cache, ehcache, etc.? Thanks

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• Is any solution the correct solution?

  - by Eli

  I always think to myself after solving a programming challenge that I have been tied up with for some time, "It works, thats good enough". I don't think this is really the correct mindset, in my opinion and I think I should always be trying to code with the greatest performance. Anyway, with this said, I just tried a ProjectEuler question. Specifically question #2. How could I have improved this solution. I feel like its really verbose. Like I'm passing the previous number in recursion. <?php /* Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be: 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ... Find the sum of all the even-valued terms in the sequence which do not exceed four million. */ function fibonacci ( $number, $previous = 1 ) { global $answer; $fibonacci = $number + $previous; if($fibonacci > 4000000) return; if($fibonacci % 2 == 0) { $answer = is_numeric($answer) ? $answer + $fibonacci : $fibonacci; } return fibonacci($fibonacci, $number); } fibonacci(1); echo $answer; ?> Note this isn't homework. I left school hundreds of years ago. I am just feeling bored and going through the Project Euler questions

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• iPad + OpenGL ES2. Why the Puzzling Virtual Memory Spike During Device Reorientation?

  - by dugla

  I've been spending the afternoon starring at Xcode Instruments memory monitor trying to decipher the following memory issue. I have a fullscreen OpenGL ES2 app running on iPad. I am fanatical about memory issues so my retains/releases are all nicely balanced. I closely monitor memory leaks. My app is basically squeeky clean. Except occassionally when I reorient the device. Portrait to Landscape. Back and forth I rock the device stress testing my discarding and rebuilding of the OpenGL framebuffer. The ambient memory footprint of my app is about 70MB Real Mems and 180MB Virtual Mems. Real memory hardly varies at all during device rotations. However the virtual mems reading sometimes briefly spikes up to 250MB and then recedes back to 180MB. No real pattern. But clearly related discarding/rebuilding the framebuffer. I see random memory warnings in my NSlogs but the app just hums along, no worries. 1) Since iPhone OS devices don't have VM could someone explain to me what the VM reading actually means? 2) My app totally leak free and generally bulletproof dispite the VM spikes. Never crashes. Rock solid. Should I be concerned about this? 3) There is clearly something happening in OpenGL framebuffer land that is causing this but I am using the API in the proper way: paraphrasing: Discarding the framebuffer: glDeleteRenderbuffers(1, &m_colorbuffer); glDeleteFramebuffers(1, &m_framebuffer); Rebuilding the framebuffer: glGenFramebuffers(1, &m_framebuffer); glGenRenderbuffers(1, &m_colorbuffer); Is there some other memory flushing trick I have missed? Thanks for any insight. Cheers, Doug

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• DrScheme versus mzscheme: treatment of definitions

  - by speciousfool

  One long term project I have is working through all the exercises of SICP. I noticed something a bit odd with the most recent exercise. I am testing a Huffman encoding tree. When I execute the following code in DrScheme I get the expected result: (a d a b b c a) However, if I execute this same code in mzscheme by calling (load "2.67.scm") or by running mzscheme -f 2.67.scm, it reports: symbols: expected symbols as arguments, given: (leaf D 1) My question is: why? Is it because mzscheme and drscheme use different rules for loading program definitions? The program code is below. ;; Define an encoding tree and a sample message ;; Use the decode procedure to decode the message, and give the result. (define (make-leaf symbol weight) (list 'leaf symbol weight)) (define (leaf? object) (eq? (car object) 'leaf)) (define (symbol-leaf x) (cadr x)) (define (weight-leaf x) (caddr x)) (define (make-code-tree left right) (list left right (append (symbols left) (symbols right)) (+ (weight left) (weight right)))) (define (left-branch tree) (car tree)) (define (right-branch tree) (cadr tree)) (define (symbols tree) (if (leaf? tree) (list (symbol-leaf tree)) (caddr tree))) (define (weight tree) (if (leaf? tree) (weight-leaf tree) (cadddr tree))) (define (decode bits tree) (define (decode-1 bits current-branch) (if (null? bits) '() (let ((next-branch (choose-branch (car bits) current-branch))) (if (leaf? next-branch) (cons (symbol-leaf next-branch) (decode-1 (cdr bits) tree)) (decode-1 (cdr bits) next-branch))))) (decode-1 bits tree)) (define (choose-branch bit branch) (cond ((= bit 0) (left-branch branch)) ((= bit 1) (right-branch branch)) (else (error "bad bit -- CHOOSE-BRANCH" bit)))) (define (test s-exp) (display s-exp) (newline)) (define sample-tree (make-code-tree (make-leaf 'A 4) (make-code-tree (make-leaf 'B 2) (make-code-tree (make-leaf 'D 1) (make-leaf 'C 1))))) (define sample-message '(0 1 1 0 0 1 0 1 0 1 1 1 0)) (test (decode sample-message sample-tree))

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• Recursively adding threads to a Java thread pool

  - by Leith

  I am working on a tutorial for my Java concurrency course. The objective is to use thread pools to compute prime numbers in parallel. The design is based on the Sieve of Eratosthenes. It has an array of n bools, where n is the largest integer you are checking, and each element in the array represents one integer. True is prime, false is non prime, and the array is initially all true. A thread pool is used with a fixed number of threads (we are supposed to experiment with the number of threads in the pool and observe the performance). A thread is given a integer multiple to process. The thread then finds the first true element in the array that is not a multiple of thread's integer. The thread then creates a new thread on the thread pool which is given the found number. After a new thread is formed, the existing thread then continues to set all multiples of it's integer in the array to false. The main program thread starts the first thread with the integer '2', and then waits for all spawned threads to finish. It then spits out the prime numbers and the time taken to compute. The issue I have is that the more threads there are in the thread pool, the slower it takes with 1 thread being the fastest. It should be getting faster not slower! All the stuff on the internet about Java thread pools create n worker threads the main thread then wait for all threads to finish. The method I use is recursive as a worker can spawn more worker threads. I would like to know what is going wrong, and if Java thread pools can be used recursively.

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• Detecting duplicate values in a column of a Datatable while traversing through It

  - by Ashish Gupta

  I have a Datatable with Id(guid) and Name(string) columns. I traverse through the data table and run a validation criteria on the Name (say, It should contain only letters and numbers) and then adding the corresponding Id to a List If name passes the validation. Something like below:- List<Guid> validIds=new List<Guid>(); foreach(DataRow row in DataTable1.Rows) { if(IsValid(row["Name"]) { validIds.Add((Guid)row["Id"]); } } In addition to this validation I should also check If the name is not repeating in the whole datatable (even for the case-sensitiveness), If It is repeating, I should not add the corresponding Id in the List. Things I am thinking/have thought about:- 1) I can have another List, check for the "Name" in the same, If It exists, will add the corresponding Guild 2) I cannot use HashSet as that would treat "Test" and "test" as different strings and not duplicates. 3) Take the DataTable to another one where I have the disctict names (this I havent tried and the code might be incorrect, please correct me whereever possible) DataTable dataTableWithDistinctName = new DataTable(); dataTableWithDistinctName.CaseSensitive=true CopiedDataTable=DataTable1.DefaultView.ToTable(true,"Name"); I would loop through the original datatable and check the existence of the "Name" in the CopiedDataTable, If It exists, I wont add the Id to the List. Are there any better and optimum way to achieve the same? I need to always think of performance. Although there are many related questions in SO, I didnt find a problem similar to this. If you could point me to a question similar to this, It would be helpful. Thanks

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• .NET WF4: Should it be in the middle of everything?

  - by stimpy77

  I am aware that WF4 (Windows Workflow 4.0, part of .NET 4.0) is a significant rework and redesign of WF3, where much of what made WF3 a poor technology choice has been cleaned up in WF4. For example, as far as I can tell, WF4 (Windows Workflow 4.0) activities are more or less testable with [TestMethod] and mocking. This among other things, like improved performance, has grabbed my attention about the technology again, whereas I had previously pooh-poohed WF3. I'm working on a new architecture for essentially an n-tier collaborative application (not enterprise-class, just a smallish project with potential to grow significantly) where I'm already trying to discipline myself to use IoC and, to some extent, TDD, and I'm wondering, in general terms, whether it is wiser to just hand-code workflow logic or if I should delve into learning and integrating WF4 so that WF becomes literally the controller of the entire application, i.e. the practical C in "MVC" (not ASP.NET MVC but rather the pattern). So should workflow activities in WF4 be the primary controller for a highly expandable/growable web-based collaborative application? Or am I asking entirely the wrong question? This is a vague question, I'm sure, so abstract answers are as welcome as specific ones.

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• Programmatically copying custom content type and columns from one web to another

  - by BeraCim

  Hi all: I'm experiencing a very stubborn problem when copying custom content type and its columns from one web to another within the same site. Basically, this is the code that I have: foreach (SPField field in existingWeb.Fields) { if (!destinationWeb.Fields.ContainsField(field.Title)) { destinationWeb.Fields.AddFieldAsXml(field.SchemaXml); destinationWeb.Update(); } } foreach (SPContentType existingWebCt in destinationWeb.ContentType) { SPContentType newContentType = new SPContentType(existingWebCt.Parent, destinationWeb.ContentTypes, existingWebCt.Name); foreach (SPFieldLink fieldLink in existingWebCt.FieldLinks) { SPField sourceField = existingWebCt.Fields[fieldLink.Id]; if (destinationWeb.Fields.ContainsField(sourceField.Title)) { SPFieldLink destinationWebFieldLink = new SPFieldLink(destinationWeb.Fields[sourceField.Title]); newContentType.FieldLinks.Add(destinationWebFieldLink); } } } existingWeb and destinationWeb are 2 webs within the same site. The code runs fine. But the problem is that in the SITE Content Type screen (under site settings), when I click the custom column link in the custom content type, I got an error saying: Invalid field name {UID}. The UID is the same UID as the custom column in the existing site. I checked with my web settings after completion. I can see the custom list (which I created with an item for testing purpose), but the custom column is gone from the view (though the actual data is still there... just have to check the box to get it to display). But I think that is less important... more of fyi. I've also gotten a variety of different exceptions should I copy things wrongly. Google has failed to help me out on this one. Does anyone know what I'm missing in order to get that link to work again? Thanks.

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• Why is Available Physical Memory (dwAvailPhys) > Available Virtual Memory (dwAvailVirtual) in call G

  - by Andrew

  I am playing with an MSDN sample to do memory stress testing (see: http://msdn.microsoft.com/en-us/magazine/cc163613.aspx) and an extension of that tool that specifically eats physical memory (see http://www.donationcoder.com/Forums/bb/index.php?topic=14895.0;prev_next=next). I am obviously confused though on the differences between Virtual and Physical Memory. I thought each process has 2 GB of virtual memory (although I also read 1.5 GB because of "overhead". My understanding was that some/all/none of this virtual memory could be physical memory, and the amount of physical memory used by a process could change over time (memory could be swapped out to disc, etc.)I further thought that, in general, when you allocate memory, the operating system could use physical memory or virtual memory. From this, I conclude that dwAvailVirtual should always be equal to or greater than dwAvailPhys in the call GlobalMemoryStatus. However, I often (always?) see the opposite. What am I missing. I apologize in advance if my question is not well formed. I'm still trying to get my head around the whole memory management system in Windows. Tutorials/Explanations/Book recs are most welcome! Andrew

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• What's are the best readings to start using WPF instead of WinForms?

  - by Ivan

  Keeping in mind what CannibalSmith once said - "All the answers are saying "WPF is different". That's a huge understatement. You not only have to learn lots of new stuff - you must forget everything you've learned from Forms. It's a completely new way of doing UI." .. and having many years of experience with visual Windows desktop applications development (VB6, Borland C++ Builder VCL, WinForms) (which is hard to forget), how do I quickly move to developing to say well-formed WPF applications with Visual Studio? I don't need boozy-woozy graphics to give my app look and feel of a Hollywood blockbuster or a million dollar pyjamas. I always loved tidiness of standard Windows common controls and UI design guidelines, end even more I enjoyed them under Vista Glass Aero Graphite sauce. I am perfectly satisfied with WinForms but I want to my applications to be built of the most efficient and up-to-date standard technologies and architectured according to the most efficient and flexible patterns of today and tomorrow, leveraging interface-based integration and functionality reuse and to take all advantages of modern hardware and APIs to maximize performance, usability, reliability, maintainability, extensibility, etc. I very much like the idea of separating view, logic and data, letting a view to take all advantages of the platform (may it run as a web browser applet on a thin client or as a desktop application on a PC with a latest GPU), letting logic be reused, parallelized and seamlessly evolve, storing data in a well structured format in a right place. But... while moving from VB6 to Borland C++ Builder was very easy (no books/tutorials needed to turn it on and start working) (assuming I already knew C++), moving from BCB to WinForms was the same seamless, it does not seem any obvious to me how to do with WPF. So how do I best convert myself from a WinForms developer into a right-way thinking and doing WPF developer?

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• Python interface to PayPal - urllib.urlencode non-ASCII characters failing

  - by krys

  I am trying to implement PayPal IPN functionality. The basic protocol is as such: The client is redirected from my site to PayPal's site to complete payment. He logs into his account, authorizes payment. PayPal calls a page on my server passing in details as POST. Details include a person's name, address, and payment info etc. I need to call a URL on PayPal's site internally from my processing page passing back all the params that were passed in abovem and an additional one called 'cmd' with a value of '_notify-validate'. When I try to urllib.urlencode the params which PayPal has sent to me, I get a: While calling send_response_to_paypal. Traceback (most recent call last): File "<snip>/account/paypal/views.py", line 108, in process_paypal_ipn verify_result = send_response_to_paypal(params) File "<snip>/account/paypal/views.py", line 41, in send_response_to_paypal params = urllib.urlencode(params) File "/usr/local/lib/python2.6/urllib.py", line 1261, in urlencode v = quote_plus(str(v)) UnicodeEncodeError: 'ascii' codec can't encode character u'\ufffd' in position 9: ordinal not in range(128) I understand that urlencode does ASCII encoding, and in certain cases, a user's contact info can contain non-ASCII characters. This is understandable. My question is, how do I encode non-ASCII characters for POSTing to a URL using urllib2.urlopen(req) (or other method) Details: I read the params in PayPal's original request as follows (the GET is for testing): def read_ipn_params(request): if request.POST: params= request.POST.copy() if "ipn_auth" in request.GET: params["ipn_auth"]=request.GET["ipn_auth"] return params else: return request.GET.copy() The code I use for sending back the request to PayPal from the processing page is: def send_response_to_paypal(params): params['cmd']='_notify-validate' params = urllib.urlencode(params) req = urllib2.Request(PAYPAL_API_WEBSITE, params) req.add_header("Content-type", "application/x-www-form-urlencoded") response = urllib2.urlopen(req) status = response.read() if not status == "VERIFIED": logging.warn("PayPal cannot verify IPN responses: " + status) return False return True Obviously, the problem only arises if someone's name or address or other field used for the PayPal payment does not fall into the ASCII range.

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• What is the correct connection string for clsql when accessing ms sqlserver using odbc?

  - by nunb

  I am accessing a database on another machine from an OS X server. After setting up freetds through macports and creating the freetds.conf file like so: dump file = /tmp/freetds.log # nunb our Microsoft server [winnt] host = 192.168.0.2 port = 1433 tds version = 8.0 I have the following test commands that work: Test freetds works: tsql -S winnt -U sa 1> use myDB; 2> select count (*) from "sysObjects"; 3> go ODBC is setup through /Applications/Utilities/ODBC\ Administrator.app, with dsn "gmb" using the freeTDS driver and a ServerName of "winnt" -- testing it yields: iodbctest "dsn=gmb;uid=sa;pwd=foo" SQL>select count (*) from "sysObjects"; = 792 Now I run the following code in lisp: (require 'asdf) (setf asdf:*central-registry* nil) (push #P"/Users/way/ff/clbuild/systems/" asdf:*central-registry*) (asdf:oos 'asdf:load-op 'cffi) (asdf:oos 'asdf:load-op 'clsql) (asdf:operate 'asdf:test-op 'cffi) (asdf:oos 'asdf:load-op 'clsql-odbc) (asdf:oos 'asdf:test-op 'clsql-odbc) (in-package :clsql-user) (connect '("gmb" "sa" "foo") :database-type :odbc) This drops me in the debugger with the error: debugger invoked on a SQL-DATABASE-ERROR in thread #<THREAD "initial thread" RUNNING {1194EA31}>: A database error occurred: NIL / IM002 [iODBC][Driver Manager]Data source name not found and no default driver specified. Driver could not be loaded Type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL

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