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• XML: Process large data

  - by Atmocreations

  Hello What XML-parser do you recommend for the following purpose: The XML-file (formatted, containing whitespaces) is around 800 MB. It mostly contains three types of tag (let's call them n, w and r). They have an attribute called id which i'd have to search for, as fast as possible. Removing attributes I don't need could save around 30%, maybe a bit more. First part for optimizing the second part: Is there any good tool (command line linux and windows if possible) to easily remove unused attributes in certain tags? I know that XSLT could be used. Or are there any easy alternatives? Also, I could split it into three files, one for each tag to gain speed for later parsing... Speed is not too important for this preparation of the data, of course it would be nice when it took rather minutes than hours. Second part: Once I have the data prepared, be it shortened or not, I should be able to search for the ID-attribute I was mentioning, this being time-critical. Estimations using wc -l tell me that there are around 3M N-tags and around 418K W-tags. The latter ones can contain up to approximately 20 subtags each. W-Tags also contain some, but they would be stripped away. "All I have to do" is navigating between tags containing certain id-attributes. Some tags have references to other id's, therefore giving me a tree, maybe even a graph. The original data is big (as mentioned), but the resultset shouldn't be too big as I only have to pick out certain elements. Now the question: What XML parsing library should I use for this kind of processing? I would use Java 6 in a first instance, with having in mind to be porting it to BlackBerry. Might it be useful to just create a flat file indexing the id's and pointing to an offset in the file? Is it even necessary to do the optimizations mentioned in the upper part? Or are there parser known to be quite as fast with the original data? Little note: To test, I took the id being on the very last line on the file and searching for the id using grep. This took around a minute on a Core 2 Duo. What happens if the file grows even bigger, let's say 5 GB? I appreciate any notice or recommendation. Thank you all very much in advance and regards

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• Scheme Formatting Help

  - by Logan

  I've been working on a project for school that takes functions from a class file and turns them into object/classes. The assignment is all about object oriented programming in scheme. My problem however is that my code doesn't format right. The output it gives me whenever I give it a file to pass in wraps the methods of the class in a list, making it so that the class never really gets declared. I can't for the life of me figure out how to get the parenthesis wrapping the method list to remove. I would really appreciate any help. Below is the code and the class file. ;;;; PART1 --- A super-easy set of classes. Just models points and lines. Tests all of the ;; basics of class behavior without touching on anything particularly complex. (class pointInstance (parent:) (constructor_args:) (ivars: (myx 1) (myy 2)) (methods: (getx () myx) (gety () myy) (setx (x) (set! myx x)) (show () (begin (display "[") (display myx) (display ",") (display myy) (display "]"))) )) (require (lib "trace.ss")) ;; Continue reading until you hit the end of the file, all the while ;; building a list with the contents (define load-file (lambda (port) (let ((rec (read port))) (if (eof-object? rec) '() (cons rec (load-file port)))))) ;; Open a port based on a file name using open-input-file (define (load fname) (let ((fport (open-input-file fname))) (load-file fport))) ;(define lis (load "C:\\Users\\Logan\\Desktop\\simpletest.txt")) ;(define lis (load "C:\\Users\\Logan\\Desktop\\complextest.txt")) (define lis (load "C:\\Users\\Logan\\Desktop\\pointinstance.txt")) ;(display (cdaddr (cdddar lis))) (define makeMethodList (lambda (listToMake retList) ;(display listToMake) (cond [(null? listToMake) retList ;(display "The list passed in to parse was null") ] [else (makeMethodList (cdr listToMake) (append retList (list (getMethodLine listToMake)))) ] ) )) ;(trace makeMethodList) ;this works provided you just pass in the function line (define getMethodLine (lambda (functionList) `((eq? (car msg) ,(caar functionList)) ,(caddar functionList)))) (define load-classes (lambda paramList (cond [(null? paramList) (display "Your parameters are null, man.")] [(null? (car paramList))(display "Done creating class definitions.")] [(not (null? (car paramList))) (begin (let* ((className (cadaar paramList)) (classInstanceVars (cdaddr (cddaar paramList))) (classMethodList (cdr (cadddr (cddaar paramList)))) (desiredMethodList (makeMethodList classMethodList '())) ) ;(display "Classname: ") ;(display className) ;(newline)(newline) ;(display "Class Instance Vars: ") ;(display classInstanceVars) ;(newline)(newline) ;(display "Class Method List: ") ;(display classMethodList) ;(newline) ;(display "Desired Method List: ") ;(display desiredMethodList)) ;(newline)(newline) ;---------------------------------------------------- ;do not delete the below code!` `(define ,className (let ,classInstanceVars (lambda msg ;return the function list here (cond ,(makeMethodList classMethodList '()))) )) ;--------------------------------------------------- ))] ) )) (load-classes lis) ;(load-classes lis) ;(load-classes-helper lis) ;(load-classes "simpletest.txt") ;(load-classes "complextest.txt") ;method list ;(display (cdr (cadddr (cddaar <class>))))

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• Modeling distribution of performance measurements

  - by peterchen

  How would you mathematically model the distribution of repeated real life performance measurements - "Real life" meaning you are not just looping over the code in question, but it is just a short snippet within a large application running in a typical user scenario? My experience shows that you usually have a peak around the average execution time that can be modeled adequately with a Gaussian distribution. In addition, there's a "long tail" containing outliers - often with a multiple of the average time. (The behavior is understandable considering the factors contributing to first execution penalty). My goal is to model aggregate values that reasonably reflect this, and can be calculated from aggregate values (like for the Gaussian, calculate mu and sigma from N, sum of values and sum of squares). In other terms, number of repetitions is unlimited, but memory and calculation requirements should be minimized. A normal Gaussian distribution can't model the long tail appropriately and will have the average biased strongly even by a very small percentage of outliers. I am looking for ideas, especially if this has been attempted/analysed before. I've checked various distributions models, and I think I could work out something, but my statistics is rusty and I might end up with an overblown solution. Oh, a complete shrink-wrapped solution would be fine, too ;) Other aspects / ideas: Sometimes you get "two humps" distributions, which would be acceptable in my scenario with a single mu/sigma covering both, but ideally would be identified separately. Extrapolating this, another approach would be a "floating probability density calculation" that uses only a limited buffer and adjusts automatically to the range (due to the long tail, bins may not be spaced evenly) - haven't found anything, but with some assumptions about the distribution it should be possible in principle. Why (since it was asked) - For a complex process we need to make guarantees such as "only 0.1% of runs exceed a limit of 3 seconds, and the average processing time is 2.8 seconds". The performance of an isolated piece of code can be very different from a normal run-time environment involving varying levels of disk and network access, background services, scheduled events that occur within a day, etc. This can be solved trivially by accumulating all data. However, to accumulate this data in production, the data produced needs to be limited. For analysis of isolated pieces of code, a gaussian deviation plus first run penalty is ok. That doesn't work anymore for the distributions found above. [edit] I've already got very good answers (and finally - maybe - some time to work on this). I'm starting a bounty to look for more input / ideas.

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• Fulltext search for django : Mysql not so bad ? (vs sphinx, xapian)

  - by Eric

  I am studying fulltext search engines for django. It must be simple to install, fast indexing, fast index update, not blocking while indexing, fast search. After reading many web pages, I put in short list : Mysql MYISAM fulltext, djapian/python-xapian, and django-sphinx I did not choose lucene because it seems complex, nor haystack as it has less features than djapian/django-sphinx (like fields weighting). Then I made some benchmarks, to do so, I collected many free books on the net to generate a database table with 1 485 000 records (id,title,body), each record is about 600 bytes long. From the database, I also generated a list of 100 000 existing words and shuffled them to create a search list. For the tests, I made 2 runs on my laptop (4Go RAM, Dual core 2.0Ghz): the first one, just after a server reboot to clear all caches, the second is done juste after in order to test how good are cached results. Here are the "home made" benchmark results : 1485000 records with Title (150 bytes) and body (450 bytes) Mysql 5.0.75/Ubuntu 9.04 Fulltext : ========================================================================== Full indexing : 7m14.146s 1 thread, 1000 searchs with single word randomly taken from database : First run : 0:01:11.553524 next run : 0:00:00.168508 Mysql 5.5.4 m3/Ubuntu 9.04 Fulltext : ========================================================================== Full indexing : 6m08.154s 1 thread, 1000 searchs with single word randomly taken from database : First run : 0:01:11.553524 next run : 0:00:00.168508 1 thread, 100000 searchs with single word randomly taken from database : First run : 9m09s next run : 5m38s 1 thread, 10000 random strings (random strings should not be found in database) : just after the 100000 search test : 0:00:15.007353 1 thread, boolean search : 1000 x (+word1 +word2) First run : 0:00:21.205404 next run : 0:00:00.145098 Djapian Fulltext : ========================================================================== Full indexing : 84m7.601s 1 thread, 1000 searchs with single word randomly taken from database with prefetch : First run : 0:02:28.085680 next run : 0:00:14.300236 python-xapian Fulltext : ========================================================================== 1 thread, 1000 searchs with single word randomly taken from database : First run : 0:01:26.402084 next run : 0:00:00.695092 django-sphinx Fulltext : ========================================================================== Full indexing : 1m25.957s 1 thread, 1000 searchs with single word randomly taken from database : First run : 0:01:30.073001 next run : 0:00:05.203294 1 thread, 100000 searchs with single word randomly taken from database : First run : 12m48s next run : 9m45s 1 thread, 10000 random strings (random strings should not be found in database) : just after the 100000 search test : 0:00:23.535319 1 thread, boolean search : 1000 x (word1 word2) First run : 0:00:20.856486 next run : 0:00:03.005416 As you can see, Mysql is not so bad at all for fulltext search. In addition, its query cache is very efficient. Mysql seems to me a good choice as there is nothing to install (I need just to write a small script to synchronize an Innodb production table to a MyISAM search table) and as I do not really need advanced search feature like stemming etc... Here is the question : What do you think about Mysql fulltext search engine vs sphinx and xapian ?

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• NSFetchedResultsController - Delegate methods crashing under iPhone OS 3.0, but NOT UNDER 3.1

  - by Scott Langendyk

  Hey guys, so I've got my NSFetchedResultsController working fine under the 3.1 SDK, however I start getting some weird errors, specifically in the delegate methods when I try it under 3.0. I've determined that this is related to the NSFetchedResultsControllerDelegate methods. This is what I have set up. The inEditingMode stuff has to do with the way I've implemented adding another static section to the table. - (void)controllerWillChangeContent:(NSFetchedResultsController*)controller { [self.tableView beginUpdates]; } - (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type{ NSIndexSet *sectionSet = [NSIndexSet indexSetWithIndex:sectionIndex]; if(self.inEditingMode){ sectionSet = [NSIndexSet indexSetWithIndex:sectionIndex + 1]; } switch (type) { case NSFetchedResultsChangeInsert: [self.tableView insertSections:sectionSet withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeDelete: [self.tableView deleteSections:sectionSet withRowAnimation:UITableViewRowAnimationFade]; break; default: [self.tableView reloadData]; break; } } - (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath{ NSIndexPath *relativeIndexPath = indexPath; NSIndexPath *relativeNewIndexPath = newIndexPath; if(self.inEditingMode){ relativeIndexPath = [NSIndexPath indexPathForRow:indexPath.row inSection:indexPath.section + 1]; relativeNewIndexPath = [NSIndexPath indexPathForRow:newIndexPath.row inSection:newIndexPath.section + 1]; } switch(type) { case NSFetchedResultsChangeInsert: [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:relativeNewIndexPath] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeDelete: [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:relativeIndexPath] withRowAnimation:UITableViewRowAnimationFade]; break; default: [self.tableView reloadData]; break; } } -(void)controllerDidChangeContent:(NSFetchedResultsController *)controller{ [self.tableView endUpdates]; } When I add an entity to the managed object context, I get the following error: Serious application error. Exception was caught during Core Data change processing: *** -[NSCFArray objectAtIndex:]: index (1) beyond bounds (1) with userInfo (null) I put a breakpoint on objc_exception_throw, and the crash seems to be occuring inside of controllerDidChangeContent. If I comment out all of the self.tableView methods, and put a single [self.tableView reloadData] inside of controllerDidChangeContent, everything works as expected. Anybody have any idea as to why this is happening?

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• Building the WAR with m2eclipse in combination with WTP (handling webResources)

  - by waxwing

  I have a situation where I have a web application that is built using maven (i.e., maven-war-plugin). For each code modification, we have had to manually launch maven and restart the application server. Now, to reduce build cycle overhead, I want to use WTP to publish the webapp. Now, we have resource processing with Maven, and there are some additional Maven tasks defined in our POM when building the webapp. Therefore m2eclipse seems like a natural solution. I have gotten far enough that the Maven builder is running these tasks and filtering resources correctly. However, when I choose "Run on Server", the WAR file does not look like it would if I built it in Maven. I am guessing that this is because WTP actually builds the WAR, and not the m2eclipse builder. So even though we have configured the maven-war-plugin in our POM, those settings are not used. Below is a snippet with our maven-war-plugin configuration. What is configured under "webResources" is not picked up, it appears: <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>2.1-alpha-2</version> <configuration> <outputDirectory>${project.build.directory}</outputDirectory> <workDirectory>${project.build.directory}/work</workDirectory> <webappDirectory>${project.build.webappDirectory}</webappDirectory> <cacheFile>${project.build.webappDirectory}/webapp-cache.xml</cacheFile> <filteringDeploymentDescriptors>true</filteringDeploymentDescriptors> <nonFilteredFileExtensions> <nonFilteredFileExtension>pdf</nonFilteredFileExtension> <nonFilteredFileExtension>png</nonFilteredFileExtension> <nonFilteredFileExtension>gif</nonFilteredFileExtension> <nonFilteredFileExtension>jsp</nonFilteredFileExtension> </nonFilteredFileExtensions> <webResources> <!-- Add generated WSDL:s and XSD:s for the web service api. --> <resource> <directory>${project.build.directory}/jaxws/wsgen/wsdl</directory> <targetPath>WEB-INF/wsdl</targetPath> <filtering>false</filtering> <includes> <include>**/*</include> </includes> </resource> </webResources> </configuration> Do I need to reconfigure these resources to be handled elsewhere, or is there a better solution?

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• What should I do or don't do to avoid Delphi "push dword" bug.

  - by Maksee

  I found that Delphi 5 generates invalid assembly code in specific cases. I can't understand in what cases in general. The example below produces access violation since a very strange optimization occurs. For a byte in a record or array Delphi generates push dword [...], pop ebx, mov .., bl that works correctly if there are data after this byte (we need at least three to push dword correctly), but fails if the data is inaccessible. I emulated the strict boundaries here with win32 Virtual* functions Specifically the error occurs when the last byte from the block accessed inside FeedBytesToClass procedure. And if I try to change something like using data array instead of object property of remove actionFlag variable, Delphi generates correct assembly instructions. const BlockSize = 4096; type TSomeClass = class private fBytes: PByteArray; public property Bytes: PByteArray read fBytes; constructor Create; destructor Destroy;override; end; constructor TSomeClass.Create; begin inherited Create; GetMem(fBytes, BlockSize); end; destructor TSomeClass.Destroy; begin FreeMem(fBytes); inherited; end; procedure FeedBytesToClass(SrcDataBytes: PByteArray; Count: integer); var j: integer; Ofs: integer; actionFlag: boolean; AClass: TSomeClass; begin AClass:=TSomeClass.Create; try actionFlag:=true; for j:=0 to Count-1 do begin Ofs:=j; if actionFlag then begin AClass.Bytes[Ofs]:=SrcDataBytes[j]; end; end; finally AClass.Free; end; end; procedure TForm31.Button1Click(Sender: TObject); var SrcDataBytes: PByteArray; begin SrcDataBytes:=VirtualAlloc(Nil, BlockSize, MEM_COMMIT, PAGE_READWRITE); try if VirtualLock(SrcDataBytes, BlockSize) then try FeedBytesToClass(SrcDataBytes, BlockSize); finally VirtualUnLock(SrcDataBytes, BlockSize); end; finally VirtualFree(SrcDataBytes, MEM_DECOMMIT, BlockSize); end; end; Initially the error occured when I used access to RGB data of bitmap bits, but the code there is too complex so I narrowed it to this fragment. So the question is what is here so specific that makes Delphi produce push,pop,mov optimization. I need to know this in order to avoid such side effects in general.

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• help with jquery ajax and templates in asp.net mvc

  - by NachoF

  So I have a complex form for an IncomeDeclaration. Its going to display a textfield GrossIncome for each Activity that the IncomeDeclaration is related to... this all gets done on the server and works just fine.... the problem is. The User should also be able to add Activities on the fly.. through javascript... so when the user clicks on Add Activity a Dropdown and a textfield must be appended to the bottom the activities list... heres what Ive got so far <tbody id="activities"> @Html.EditorFor(model => model.income.EconomicActivityIncomeDeclarations) </tbody> </table> <a href="#" id="add_activity">Agregar Otra Actividad</a> </fieldset> <script type="text/javascript"> $("#add_activity").click(function () { $.getJSON('/IncomeDeclarations/GetEconomicActivities', function (data) { var select = new Select(); var data = new Array(); for (var i = 0; i < data.length; i++) { var option = new Option(data[i]["name"], data[i]["i"]) //should do something here } //should call the template and append to #activities }); }); </script> <script id="template" type="text/x-jquery-tmpl"> <tr> <td><select name="income.EconomicActivityIncomeDeclarations[${SomeNumber}].EconomicActivityId"> ${MyOptions} </select></td> <td><input type="text" name="income.EconomicActivityIncomeDeclarations[${SomeNumber}].GrossIncome" /></td>> </tr> </script> } The name attribute for both the select and the text_field is key for this to work... otherwise modelbinding wont work... I would think that if the SomeNumber variable is set to new Date.GetTime() model Binding should work just fine... I actually dont see the need of ajax for this but thats another topic.. I just havent figured out a way to do this without ajax... right now I want to get the template to work and append the form elements to the bottom of the list.

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• Validate a string in a table in SQL Server - CLR function or T-SQL (Question updated)

  - by Ashish Gupta

  I need to check If a column value (string) in SQL server table starts with a small letter and can only contain '_', '-', numbers and alphabets. I know I can use a SQL server CLR function for that. However, I am trying to implement that validation using a scalar UDF and could make very little here...I can use 'NOT LIKE', but I am not sure how to make sure I validate the string irrespective of the order of characters or in other words write a pattern in SQL for this. Am I better off using a SQL CLR function? Any help will be appreciated.. Thanks in advance Thank you everyone for their comments. This morning, I chose to go CLR function way. For the purpose of what I was trying to achieve, I created one CLR function which does the validation of an input string and have that called from a SQL UDF and It works well. Just to measure the performance of t-SQL UDF using SQL CLR function vs t- SQL UDF, I created a SQL CLR function which will just check if the input string contains only small letters, it should return true else false and have that called from a UDF (IsLowerCaseCLR). After that I also created a regular t-SQL UDF(IsLowerCaseTSQL) which does the same thing using the 'NOT LIKE'. Then I created a table (Person) with columns Name(varchar) and IsValid(bit) columns and populate that with names to test. Data :- 1000 records with 'Ashish' as value for Name column 1000 records with 'ashish' as value for Name column then I ran the following :- UPDATE Person Set IsValid=1 WHERE dbo.IsLowerCaseTSQL (Name) Above updated 1000 records (with Isvalid=1) and took less than a second. I deleted all the data in the table and repopulated the same with same data. Then updated the same table using Sql CLR UDF (with Isvalid=1) and this took 3 seconds! If update happens for 5000 records, regular UDF takes 0 seconds compared to CLR UDF which takes 16 seconds! I am very less knowledgeable on t-SQL regular expression or I could have tested my actual more complex validation criteria. But I just wanted to know, even I could have written that, would that have been faster than the SQL CLR function considering the example above. Are we using SQL CLR because we can implement we can implement lot richer logic which would have been difficult otherwise If we write in regular SQL. Sorry for this long post. I just want to know from the experts. Please feel free to ask if you could not understand anything here. Thank you again for your time.

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• How to configure maximum number of transport channels in WCF using basicHttpBinding?

  - by Hemant

  Consider following code which is essentially a WCF host: [ServiceContract (Namespace = "http://www.mightycalc.com")] interface ICalculator { [OperationContract] int Add (int aNum1, int aNum2); } [ServiceBehavior (InstanceContextMode = InstanceContextMode.PerCall)] class Calculator: ICalculator { public int Add (int aNum1, int aNum2) { Thread.Sleep (2000); //Simulate a lengthy operation return aNum1 + aNum2; } } class Program { static void Main (string[] args) { try { using (var serviceHost = new ServiceHost (typeof (Calculator))) { var httpBinding = new BasicHttpBinding (BasicHttpSecurityMode.None); serviceHost.AddServiceEndpoint (typeof (ICalculator), httpBinding, "http://172.16.9.191:2221/calc"); serviceHost.Open (); Console.WriteLine ("Service is running. ENJOY!!!"); Console.WriteLine ("Type 'stop' and hit enter to stop the service."); Console.ReadLine (); if (serviceHost.State == CommunicationState.Opened) serviceHost.Close (); } } catch (Exception e) { Console.WriteLine (e); Console.ReadLine (); } } } Also the WCF client program is: class Program { static int COUNT = 0; static Timer timer = null; static void Main (string[] args) { var threads = new Thread[10]; for (int i = 0; i < threads.Length; i++) { threads[i] = new Thread (Calculate); threads[i].Start (null); } timer = new Timer (o => Console.WriteLine ("Count: {0}", COUNT), null, 1000, 1000); Console.ReadLine (); timer.Dispose (); } static void Calculate (object state) { var c = new CalculatorClient ("BasicHttpBinding_ICalculator"); c.Open (); while (true) { try { var sum = c.Add (2, 3); Interlocked.Increment (ref COUNT); } catch (Exception ex) { Console.WriteLine ("Error on thread {0}: {1}", Thread.CurrentThread.Name, ex.GetType ()); break; } } c.Close (); } } Basically, I am creating 10 proxy clients and then repeatedly calling Add service method. Now if I run both applications and observe opened TCP connections using netstat, I find that: If both client and server are running on same machine, number of tcp connections are equal to number of proxy objects. It means all requests are being served in parallel. Which is good. If I run server on a separate machine, I observed that maximum 2 TCP connections are opened regardless of the number of proxy objects I create. Only 2 requests run in parallel. It hurts the processing speed badly. If I switch to net.tcp binding, everything works fine (a separate TCP connection for each proxy object even if they are running on different machines). I am very confused and unable to make the basicHttpBinding use more TCP connections. I know it is a long question, but please help!

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• Storing a set of criteria in another table

  - by bendataclear

  I have a large table with sales data, useful data below: RowID Date Customer Salesperson Product_Type Manufacturer Quantity Value 1 01-06-2004 James Ian Taps Tap Ltd 200 £850 2 02-06-2004 Apple Fran Hats Hats Inc 30 £350 3 04-06-2004 James Lawrence Pencils ABC Ltd 2000 £980 ... Many rows later... ... 185352 03-09-2012 Apple Ian Washers Tap Ltd 600 £80 I need to calculate a large set of targets from table containing values different types, target table is under my control and so far is like: TargetID Year Month Salesperson Target_Type Quantity 1 2012 7 Ian 1 6000 2 2012 8 James 2 2000 3 2012 9 Ian 2 6500 At present I am working out target types using a view of the first table which has a lot of extra columns: SELECT YEAR(Date) , MONTH(Date) , Salesperson , Quantity , CASE WHEN Manufacturer IN ('Tap Ltd','Hats Inc') AND Product_Type = 'Hats' THEN True ELSE False END AS IsType1 , CASE WHEN Manufacturer = 'Hats Inc' AND Product_Type IN ('Hats','Coats') THEN True ELSE False END AS IsType2 ... ... , CASE WHEN Manufacturer IN ('Tap Ltd','Hats Inc') AND Product_Type = 'Hats' THEN True ELSE False END AS IsType24 , CASE WHEN Manufacturer IN ('Tap Ltd','Hats Inc') AND Product_Type = 'Hats' THEN True ELSE False END AS IsType25 FROM SalesTable WHERE [some stuff here] This is horrible to read/debug and I hate it!! I've tried a few different ways of simplifying this but have been unable to get it to work. The closest I have come is to have a third table holding the definition of the types with the values for each field and the type number, this can be joined to the tables to give me the full values but I can't work out a way to cope with multiple values for each field. Finally the question: Is there a standard way this can be done or an easier/neater method other than one column for each type of target? I know this is a complex problem so if anything is unclear please let me know. Edit - What I need to get: At the very end of the process I need to have targets displayed with actual sales: Type Year Month Salesperson TargetQty ActualQty 2 2012 8 James 2000 2809 2 2012 9 Ian 6500 6251 Each row of the sales table could potentially satisfy 8 of the types. Some more points: I have 5 different columns that need to be defined against the targets (or set to NULL to include any value) I have between 30 and 40 different types that need to be defined, several of the columns could contain as many as 10 different values For point 2, if I am using a row for each permutation of values, 2 columns with 10 values each would give me 100 rows for each sales person for each month which is a lot but if this is the only way to define multiple values I will have to do this. Sorry if this makes no sense!

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• Wiki-fying a text using LPeg

  - by Stigma

  Long story coming up, but I'll try to keep it brief. I have many pure-text paragraphs which I extract from a system and re-output in wiki format so that the copying of said data is not such an arduous task. This all goes really well, except that there are no automatic references being generated for the 'topics' we have pages for, which end up needing to be added by reading through all the text and adding it in manually by changing Topic to [[Topic]]. First requirement: each topic is only to be made clickable once, which is the first occurrence. Otherwise, it would become a really spammy linkfest, which would detract from readability. To avoid issues with topics that start with the same words Second requirement: overlapping topic names should be handled in such a way that the most 'precise' topic gets the link, and in later occurrences, the less precise topics do not get linked, since they're likely not correct. Example: topics = { "Project", "Mary", "Mr. Moore", "Project Omega"} input = "Mary and Mr. Moore work together on Project Omega. Mr. Moore hates both Mary and Project Omega, but Mary simply loves the Project." output = function_to_be_written(input) -- "[[Mary]] and [[Mr. Moore]] work together on [[Project Omega]]. Mr. Moore hates both Mary and Project Omega, but Mary simply loves the [[Project]]." Now, I quickly figured out a simple or complicated string.gsub() could not get me what I need to satisfy the second requirement, as it provides no way to say 'Consider this match as if it did not happen - I want you to backtrack further'. I need the engine to do something akin to: input = "abc def ghi" -- Looping over the input would, in this order, match the following strings: -- 1) abc def ghi -- 2) abc def -- 3) abc -- 4) def ghi -- 5) def -- 6) ghi Once a string matches an actual topic and has not been replaced before by its wikified version, it is replaced. If this topic has been replaced by a wikified version before, don't replace, but simply continue the matching at the end of the topic. (So for a topic "abc def", it would test "ghi" next in both cases.) Thus I arrive at LPeg. I have read up on it, played with it, but it is considerably complex, and while I think I need to use lpeg.Cmt and lpeg.Cs somehow, I am unable to mix the two properly to make what I want to do work. I am refraining from posting my practice attempts as they are of miserable quality and probably more likely to confuse anyone than assist in clarifying my problem. (Why do I want to use a PEG instead of writing a triple-nested loop myself? Because I don't want to, and it is a great excuse to learn PEGs.. except that I am in over my head a bit. Unless it is not possible with LPeg, the first is not an option.)

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• KISS: Simple C# application which communicates with a RESTful web service.

  - by Workshop Alex

  Following the KISS principle, I suddenly realised the following: In .NET, you can use the Entity Model Framework to wrap around a database. This model can be exposed as a web service through WCF. This web service would have a very standardized definition. A client application could be created which could consume any such RESTful web service. I don't want to re-invent the wheel and it wouldn't surprise me if someone has already done this, so my question is simple: Has anyone already created a simple (desktop, not web) client application that can consume a RESTful service that's based on the Entity Framework and which will allow the user to read and write data directly to this service? Otherwise, I'll just have to "invent" this myself. :-)Problem is, the database layer and RESTful service is already finished. The RESTful service will only stay in the project during it's development phase, since we can use the database-layer assembly directly from the web applications that are build around it. When the web application is deployed, the RESTful services are just kept out of the deployment. But the database has a lot of data to manage over nearly 50 tables. When developing against a local database, we can have straight access to the database so I wouldn't need this tool for this. When it's deployed, the web application would be the only way to access the data so I could not use this tool. But we're also having a test phase where the database is stored on another system outside the local domain and this database is not available for developers. Only administrators have direct access to this database, making tests a bit more complex. However, through the RESTful service, I can still access the data directly. Thus, when some test goes wrong, I can repair the data through this connection or just create a copy of the data for tests on my local system. There's plenty of other functionality and it's even possible to just open the URL to a table service straight in Excel or XMLSpy to see the contents. But when I want to write something back, I have to write special code to do just that. A generic tool that would allow me to access the data and modify it would be easier. Since it's a generic setup around the ADO.NET Data services, this should be reasonable easy too. Thus, I can do it but hoped someone else has already done something similar. But it appears that there's no such tool made yet...

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• C# DirectSound - Capture buffers not continuous

  - by Wizche

  Hi, I'm trying to capture raw data from my line-in using DirectSound. My problem is that, from a buffer to another the data are just inconsistent, if for example I capture a sine I see a jump from my last buffer and the new one. To detected this I use a graph widget to draw the first 500 elements of the last buffer and the 500 elements from the new one: Snapshot I initialized my buffer this way: format = new WaveFormat { SamplesPerSecond = 44100, BitsPerSample = (short)bitpersample, Channels = (short)channels, FormatTag = WaveFormatTag.Pcm }; format.BlockAlign = (short)(format.Channels * (format.BitsPerSample / 8)); format.AverageBytesPerSecond = format.SamplesPerSecond * format.BlockAlign; _dwNotifySize = Math.Max(4096, format.AverageBytesPerSecond / 8); _dwNotifySize -= _dwNotifySize % format.BlockAlign; _dwCaptureBufferSize = NUM_BUFFERS * _dwNotifySize; // my capture buffer _dwOutputBufferSize = NUM_BUFFERS * _dwNotifySize / channels; // my output buffer I set my notifications one at half the buffer and one at the end: _resetEvent = new AutoResetEvent(false); _notify = new Notify(_dwCapBuffer); bpn1 = new BufferPositionNotify(); bpn1.Offset = ((_dwCapBuffer.Caps.BufferBytes) / 2) - 1; bpn1.EventNotifyHandle = _resetEvent.SafeWaitHandle.DangerousGetHandle(); bpn2 = new BufferPositionNotify(); bpn2.Offset = (_dwCapBuffer.Caps.BufferBytes) - 1; bpn2.EventNotifyHandle = _resetEvent.SafeWaitHandle.DangerousGetHandle(); _notify.SetNotificationPositions(new BufferPositionNotify[] { bpn1, bpn2 }); observer.updateSamplerStatus("Events listener initialization complete!\r\n"); And here is how I process the events. /* Process thread */ private void eventReceived() { int offset = 0; _dwCaptureThread = new Thread((ThreadStart)delegate { _dwCapBuffer.Start(true); while (isReady) { _resetEvent.WaitOne(); // Notification received /* Read the captured buffer */ Array read = _dwCapBuffer.Read(offset, typeof(short), LockFlag.None, _dwOutputBufferSize - 1); observer.updateTextPacket("Buffer: " + count.ToString() + " # " + read.GetValue(read.Length - 1).ToString() + " # " + read.GetValue(0).ToString() + "\r\n"); /* Print last/new part of the buffer to the debug graph */ short[] graphData = new short[1001]; Array.Copy(read, graphData, 1000); db.SetBufferDebug(graphData, 500); observer.updateGraph(db.getBufferDebug()); offset = (offset + _dwOutputBufferSize) % _dwCaptureBufferSize; /* Out buffer not used */ /*_dwDevBuffer.Write(0, read, LockFlag.EntireBuffer); _dwDevBuffer.SetCurrentPosition(0); _dwDevBuffer.Play(0, BufferPlayFlags.Default);*/ } _dwCapBuffer.Stop(); }); _dwCaptureThread.Start(); } Any advise? I'm sure I'm failing somewhere in the event processing, but I cant find where. I had developed the same application using the WaveIn API and it worked well. Thanks a lot...

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• trouble resolving location in <xs:import > element in C#

  - by BobC

  I'm using an XML schema document to validate incoming data documents, however the schema appears be failing during compilation at run time because it refers to a complex type which part of an external schema. The external schema is specified in a element at the top of the document. I had thought it might be an access problem, so I moved a copy of the external document to a localhost folder. I get the same error, so now I'm wondering if there might be some sort of issue with the use of the element. The schema document fragment looks like this: <xs:schema targetNamespace="http://www.smpte-ra.org/schemas/429-7/2006/CPL" xmlns:cpl="http://www.smpte-ra.org/schemas/429-7/2006/CPL" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"> ... <xs:import namespace="http://www.w3.org/2000/09/xmldsig#" schemaLocation="http://localhost/TMSWebServices/XMLSchema/xmldsig-core-schema.xsd"/> ... <xs:element name="Signer" type="ds:KeyInfoType" minOccurs="0"/> ... </xs:schema> The code I'm trying to run this with is real simple (got it from http://dotnetslackers.com/Community/blogs/haissam/archive/2008/11/06/validate-xml-against-xsd-xml-schema-using-c.aspx) string XSDFILEPATH = @"http://localhost/TMSWebServices/XMLSchema/CPL.xsd"; string XMLFILEPATH = @"C:\foo\bar\files\TestCPLs\CPL_930f5e92-be03-440c-a2ff-a13f3f16e1d6.xml"; System.Xml.XmlReaderSettings settings = new System.Xml.XmlReaderSettings(); settings.Schemas.Add(null, XSDFILEPATH); settings.ValidationType = System.Xml.ValidationType.Schema; System.Xml.XmlDocument document = new System.Xml.XmlDocument(); document.Load(XMLFILEPATH); System.Xml.XmlReader rdr = System.Xml.XmlReader.Create(new StringReader(document.InnerXml), settings); while (rdr.Read()) { } Everything goes well until the line that instantiates the XMLReader object just before the while loop. Then it fails with a type not declared error. The type that it's trying to find, KeyInfoType, is defined in one of the the documents in the import element. I've made sure the namespaces line up. I wondered if the # signs in the namespace definitions were causing a problem, but removing them had no effect, it just changed what the error looked like (i.e. "Type 'http://www.w3.org/2000/09/xmldsig:KeyInfoType' is not declared." versus "Type 'http://www.w3.org/2000/09/xmldsig#:KeyInfoType' is not declared.") My suspicion is that there's something about the processing of the element that I'm missing. Any suggestions are very welcome. Thanks!

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• Linq-to-sql Compiled Query returning object NOT belonging to submitted DataContext

  - by Vladimir Kojic

  Compiled query: public static class Machines { public static readonly Func<OperationalDataContext, short, Machine> QueryMachineById = CompiledQuery.Compile((OperationalDataContext db, short machineID) => db.Machines.Where(m => m.MachineID == machineID).SingleOrDefault() ); public static Machine GetMachineById(IUnitOfWork unitOfWork, short id) { Machine machine; // Old code (working) //var machineRepository = unitOfWork.GetRepository<Machine>(); //machine = machineRepository.Find(m => m.MachineID == id).SingleOrDefault(); // New code (making problems) machine = QueryMachineById(unitOfWork.DataContext, id); return machine; } It looks like compiled query is caching Machine object and returning the same object even if query is called from new DataContext (I’m disposing DataContext in the service but I’m getting Machine from previous DataContext). I use POCOs and XML mapping. Revised: It looks like compiled query is returning result from new data context and it is not using the one that I passed in compiled-query. Therefore I can not reuse returned object and link it to another object obtained from datacontext thru non compiled queries. [TestMethod] public void GetMachinesTest() { // Test Preparation (not important) using (var unitOfWork = IoC.Get<IUnitOfWork>()) { var machineRepository = unitOfWork.GetRepository<Machine>(); // GET ALL List<Machine> list = machineRepository.FindAll().ToList<Machine>(); VerifyIntegratedMachine(list[2], 3, "Machine 3", "333333", "G300PET", "MachineIconC.xaml", false, true, LicenseType.Licensed, "10.0.97.3", "10.0.97.3", 0); var machine = Machines.GetMachineById(unitOfWork, 3); Assert.AreSame(list[2], machine); // PASS !!!! } using (var unitOfWork = IoC.Get<IUnitOfWork>()) { var machineRepository = unitOfWork.GetRepository<Machine>(); // GET ALL List<Machine> list = machineRepository.FindAll().ToList<Machine>(); VerifyIntegratedMachine(list[2], 3, "Machine 3", "333333", "G300PET", "MachineIconC.xaml", false, true, LicenseType.Licensed, "10.0.97.3", "10.0.97.3", 0); var machine = Machines.GetMachineById(unitOfWork, 3); Assert.AreSame(list[2], machine); // FAIL !!!! } } If I run other (complex) unit tests I'm getting as expected: An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext.

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• Problems doing asynch operations in C# using Mutex.

  - by firoso

  I've tried this MANY ways, here is the current iteration. I think I've just implemented this all wrong. What I'm trying to accomplish is to treat this Asynch result in such a way that until it returns AND I finish with my add-thumbnail call, I will not request another call to imageProvider.BeginGetImage. To Clarify, my question is two-fold. Why does what I'm doing never seem to halt at my Mutex.WaitOne() call, and what is the proper way to handle this scenario? /// <summary> /// re-creates a list of thumbnails from a list of TreeElementViewModels (directories) /// </summary> /// <param name="list">the list of TreeElementViewModels to process</param> public void BeginLayout(List<AiTreeElementViewModel> list) { // *removed code for canceling and cleanup from previous calls* // Starts the processing of all folders in parallel. Task.Factory.StartNew(() => { thumbnailRequests = Parallel.ForEach<AiTreeElementViewModel>(list, options, ProcessFolder); }); } /// <summary> /// Processes a folder for all of it's image paths and loads them from disk. /// </summary> /// <param name="element">the tree element to process</param> private void ProcessFolder(AiTreeElementViewModel element) { try { var images = ImageCrawler.GetImagePaths(element.Path); AsyncCallback callback = AddThumbnail; foreach (var image in images) { Console.WriteLine("Attempting Enter"); synchMutex.WaitOne(); Console.WriteLine("Entered"); var result = imageProvider.BeginGetImage(callback, image); } } catch (Exception exc) { Console.WriteLine(exc.ToString()); // TODO: Do Something here. } } /// <summary> /// Adds a thumbnail to the Browser /// </summary> /// <param name="result">an async result used for retrieving state data from the load task.</param> private void AddThumbnail(IAsyncResult result) { lock (Thumbnails) { try { Stream image = imageProvider.EndGetImage(result); string filename = imageProvider.GetImageName(result); string imagePath = imageProvider.GetImagePath(result); var imageviewmodel = new AiImageThumbnailViewModel(image, filename, imagePath); thumbnailHash[imagePath] = imageviewmodel; HostInvoke(() => Thumbnails.Add(imageviewmodel)); UpdateChildZoom(); //synchMutex.ReleaseMutex(); Console.WriteLine("Exited"); } catch (Exception exc) { Console.WriteLine(exc.ToString()); // TODO: Do Something here. } } }

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• heroku time zone problem, logging local server time

  - by Ole Morten Amundsen

  UPDATE: Ok, I didn't formulate a good Q to be answered. I still struggle with heroku being on -07:00 UTC and I at +02:200 UTC. Q: How do I get the log written in the correct Time.zone ? The 9 hours difference, heroku (us west) - norway, is distracting to work with. I get this in my production.log (using heroku logs): Processing ProductionController#create to xml (for 81.26.51.35 at 2010-04-28 23:00:12) [POST] How do I get it to write 2010-04-29 08:00:12 +02:00 GMT ? Note that I'm running at heroku and cannot set the server time myself, as one could do at your amazon EC2 servers. Below is my previous question, I'll leave it be as it holds some interesting information about time and zones. Why does Time.now yield the server local time when I have set the another time zone in my environment.rb config.time_zone = 'Copenhagen' I've put this in a view <p> Time.zone <%= Time.zone %> </p> <p> Time.now <%= Time.now %> </p> <p> Time.now.utc <%= Time.now.utc %> </p> <p> Time.zone.now <%= Time.zone.now %> </p> <p> Time.zone.today <%= Time.zone.today %> </p> rendering this result on my app at heroku Time.zone (GMT+01:00) Copenhagen Time.now Mon Apr 26 08:28:21 -0700 2010 Time.now.utc Mon Apr 26 15:28:21 UTC 2010 Time.zone.now 2010-04-26 17:28:21 +0200 Time.zone.today 2010-04-26 Time.zone.now yields the correct result. Do I have to switch from Time.now to Time.zone.now, everywhere? Seems cumbersome. I truly don't care what the local time of the server is, it's giving me loads of trouble due to extensive use of Time.now. Am I misunderstanding anything fundamental here?

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• PHP: How to find connections between users so I can create a closed friend circle?

  - by CuSS

  Hi all, First of all, I'm not trying to create a social network, facebook is big enough! (comic) I've chosen this question as example because it fits exactly on what I'm trying to do. Imagine that I have in MySQL a users table and a user_connections table with 'friend requests'. If so, it would be something like this: Users Table: userid username 1 John 2 Amalia 3 Stewie 4 Stuart 5 Ron 6 Harry 7 Joseph 8 Tiago 9 Anselmo 10 Maria User Connections Table: userid_request userid_accepted 2 3 7 2 3 4 7 8 5 6 4 5 8 9 4 7 9 10 6 1 10 7 1 2 Now I want to find circles between friends and create a structure array and put that circle on the database (none of the arrays can include the same friends that another has already). Return Example: // First Circle of Friends Circleid => 1 CircleStructure => Array( 1 => 2, 2 => 3, 3 => 4, 4 => 5, 5 => 6, 6 => 1, ) // Second Circle of Friends Circleid => 2 CircleStructure => Array( 7 => 8, 8 => 9, 9 => 10, 10 => 7, ) I'm trying to think of an algorithm to do that, but I think it will take a lot of processing time because it would randomly search the database until it 'closes' a circle. PS: The minimum structure length of a circle is 3 connections and the limit is 100 (so the daemon doesn't search the entire database) EDIT: I've think on something like this: function browse_user($userget='random',$users_history=array()){ $user = user::get($userget); $users_history[] = $user['userid']; $connections = user::connection::getByUser($user['userid']); foreach($connections as $connection){ $userid = ($connection['userid_request']!=$user['userid']) ? $connection['userid_request'] : $connection['userid_accepted']; // Start the circle array if(in_array($userid,$users_history)) return array($user['userid'] => $userid); $res = browse_user($userid, $users_history); if($res!==false){ // Continue the circle array return $res + array($user['userid'] => $userid); } } return false; } while(true){ $res = browse_user(); // Yuppy, friend circle found! if($res!==false){ user::circle::create($res); } // Start from scratch again! } The problem with this function is that it could search the entire database without finding the biggest circle, or the best match.

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• System architecture: simple approach for setting up background tasks behind a web application -- wil

  - by Tim Molendijk

  I have a Django web application and I have some tasks that should operate (or actually: be initiated) on the background. The application is deployed as follows: apache2-mpm-worker; mod_wsgi in daemon mode (1 process, 15 threads). The background tasks have the following characteristics: they need to operate in a regular interval (every 5 minutes or so); they require the application context (i.e. the application packages need to be available in memory); they do not need any input other than database access, in order to perform some not-so-heavy tasks such as sending out e-mail and updating the state of the database. Now I was thinking that the most simple approach to this problem would be simply to piggyback on the existing application process (as spawned by mod_wsgi). By implementing the task as part of the application and providing an HTTP interface for it, I would prevent the overhead of another process that is holding all of the application into memory. A simple cronjob can be setup that sends a request to this HTTP interface every 5 minutes and that would be it. Since the application process provides 15 threads and the tasks are quite lightweight and only running every 5 minutes, I figure they would not be hindering the performance of the web application's user-facing operations. Yet... I have done some online research and I have seen nobody advocating this approach. Many articles suggest a significantly more complex approach based on a full-blown messaging component (such as Celery, which uses RabbitMQ). Although that's sexy, it sounds like overkill to me. Some articles suggest setting up a cronjob that executes a script which performs the tasks. But that doesn't feel very attractive either, as it results in creating a new process that loads the entire application into memory, performs some tiny task, and destroys the process again. And this is repeated every 5 minutes. Does not sound like an elegant solution. So, I'm looking for some feedback on my suggested approach as described in the paragraph before the preceeding paragraph. Is my reasoning correct? Am I overlooking (potential) problems? What about my assumption that application's performance will not be impeded?

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• PHP Form POST to external URL with Redirect to another URL

  - by Marlon

  So, what I am trying to accomplish is have a self-posting PHP form, POST to an external page (using CURL) which in turn redirects to another page. Currently, what is happening is that once I click "Submit" on the form (in contact.php) it will POST to itself (as it is a self-posting form). The script then prepares the POST using CURL and performs the post. The external page does its processing and then, the external page is supposed to redirect back to another page, in a referring domain. However, what happens instead, is that it seems like the contact.php page loads the HTML from the page the external page redirected to, and then, the contact.php's HTML loads after that, ON THE SAME PAGE. The effect, is what looks like two separate pages rendered as one page. Naturally, I just want to perform the POST and have the browser render the page it is supposed to redirect to as specified by the external page. Here is the code I have so far: <?php if(isset($_POST['submit'])) { doCURLPost(); } function doCURLPost() { $emailid = "2, 4"; $hotel = $_POST['hotel']; //you will need to setup an array of fields to post with //then create the post string $data = array ( "recipient" => $emailid, "subject" => "Hotel Contact Form", "redirect" => "http://www.localhost.com/thanx.htm", "Will be staying in hotel: " => $_POST['hotel'], "Name" => $_POST['Name'], "Phone" => $_POST['Phone'], "Comments" => $_POST['Comments']); $ch = curl_init(); curl_setopt($ch, CURLOPT_URL, "http://www.externallink.com/external.aspx"); curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true); curl_setopt($ch, CURLOPT_POST, true); curl_setopt($ch, CURLOPT_POSTFIELDS, $data); curl_setopt($ch, CURLOPT_HTTPHEADER, array("Referer: http://www.localhost.com/contact.php")); $output = curl_exec($ch); $info = curl_getinfo($ch); curl_close($ch); } ?>

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• Merging two XML files into one XML file using Java

  - by dmurali

  I am stuck with how to proceed with combining two different XML files(which has the same structure). When I was doing some research on it, people say that XML parsers like DOM or StAX will have to be used. But cant I do it with the regular IOStream? I am currently trying to do with the help of IOStream but this is not solving my purpose, its being more complex. For example, What I have tried is; public class GUI { public static void main(String[] args) throws Exception { // Creates file to write to Writer output = null; output = new BufferedWriter(new FileWriter("C:\\merged.xml")); String newline = System.getProperty("line.separator"); output.write(""); // Read in xml file 1 FileInputStream in = new FileInputStream("C:\\1.xml"); BufferedReader br = new BufferedReader(new InputStreamReader(in)); String strLine; while ((strLine = br.readLine()) != null) { if (strLine.contains("<MemoryDump>")){ strLine = strLine.replace("<MemoryDump>", "xmlns:xsi"); } if (strLine.contains("</MemoryDump>")){ strLine = strLine.replace("</MemoryDump>", "xmlns:xsd"); } output.write(newline); output.write(strLine); System.out.println(strLine); } // Read in xml file 2 FileInputStream in = new FileInputStream("C:\\2.xml"); BufferedReader br1 = new BufferedReader(new InputStreamReader(in)); String strLine1; while ((strLine1 = br1.readLine()) != null) { if (strLine1.contains("<MemoryDump>")){ strLine1 = strLine1.replace("<MemoryDump>", ""); } if (strLine1.contains("</MemoryDump>")){ strLine1 = strLine1.replace("</MemoryDump>", ""); } output.write(newline); output.write(strLine1); I request you to kindly let me know how do I proceed with merging two XML files by adding additional content as well. It would be great if you could provide me some example links as well..! Thank You in Advance..! System.out.println(strLine1); } }

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• Is the design notion of layers contrived?

  - by Bruce

  Hi all I'm reading through Eric Evans' awesome work, Domain-Driven Design. However, I can't help feeling that the 'layers' model is contrived. To expand on that statement, it seems as if it tries to shoe-horn various concepts into a specific, neat model, that of layers talking to each other. It seems to me that the layers model is too simplified to actually capture the way that (good) software works. To expand further: Evans says: "Partition a complex program into layers. Develop a design within each layer that is cohesive and that depends only on the layers below. Follow standard architectural patterns to provide loose coupling to the layers above." Maybe I'm misunderstanding what 'depends' means, but as far as I can see, it can either mean a) Class X (in the UI for example) has a reference to a concrete class Y (in the main application) or b) Class X has a reference to a class Y-ish object providing class Y-ish services (ie a reference held as an interface). If it means (a), then this is clearly a bad thing, since it defeats re-using the UI as a front-end to some other application that provides Y-ish functionality. But if it means (b), then how is the UI any more dependent on the application, than the application is dependent on the UI? Both are decoupled from each other as much as they can be while still talking to each other. Evans' layer model of dependencies going one way seems too neat. First, isn't it more accurate to say that each area of the design provides a module that is pretty much an island to itself, and that ideally all communication is through interfaces, in a contract-driven/responsibility-driven paradigm? (ie, the 'dependency only on lower layers' is contrived). Likewise with the domain layer talking to the database - the domain layer is as decoupled (through DAO etc) from the database as the database is from the domain layer. Neither is dependent on the other, both can be swapped out. Second, the idea of a conceptual straight line (as in from one layer to the next) is artificial - isn't there more a network of intercommunicating but separate modules, including external services, utility services and so on, branching off at different angles? Thanks all - hoping that your responses can clarify my understanding on this..

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• Faster Matrix Multiplication in C#

  - by Kyle Lahnakoski

  I have as small c# project that involves matrices. I am processing large amounts of data by splitting it into n-length chunks, treating the chucks as vectors, and multiplying by a Vandermonde** matrix. The problem is, depending on the conditions, the size of the chucks and corresponding Vandermonde** matrix can vary. I have a general solution which is easy to read, but way too slow: public byte[] addBlockRedundancy(byte[] data) { if (data.Length!=numGood) D.error("Expecting data to be just "+numGood+" bytes long"); aMatrix d=aMatrix.newColumnMatrix(this.mod, data); var r=vandermonde.multiplyBy(d); return r.ToByteArray(); }//method This can process about 1/4 megabytes per second on my i5 U470 @ 1.33GHz. I can make this faster by manually inlining the matrix multiplication: int o=0; int d=0; for (d=0; d<data.Length-numGood; d+=numGood) { for (int r=0; r<numGood+numRedundant; r++) { Byte value=0; for (int c=0; c<numGood; c++) { value=mod.Add(value, mod.Multiply(vandermonde.get(r, c), data[d+c])); }//for output[r][o]=value; }//for o++; }//for This can process about 1 meg a second. (Please note the "mod" is performing operations over GF(2^8) modulo my favorite irreducible polynomial.) I know this can get a lot faster: After all, the Vandermonde** matrix is mostly zeros. I should be able to make a routine, or find a routine, that can take my matrix and return a optimized method which will effectively multiply vectors by the given matrix, but faster. Then, when I give this routine a 5x5 Vandermonde matrix (the identity matrix), there is simply no arithmetic to perform, and the original data is just copied. ** Please note: What I use the term "Vandermonde", I actually mean an Identity matrix with some number of rows from the Vandermonde matrix appended (see comments). This matrix is wonderful because of all the zeros, and because if you remove enough rows (of your choosing) to make it square, it is an invertible matrix. And, of course, I would like to use this same routine to convert any one of those inverted matrices into an optimized series of instructions. How can I make this matrix multiplication faster? Thanks! (edited to correct my mistake with Vandermonde matrix)

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• Can LINQ-to-SQL omit unspecified columns on insert so a database default value is used?

  - by Todd Ropog

  I have a non-nullable database column which has a default value set. When inserting a row, sometimes a value is specified for the column, sometimes one is not. This works fine in TSQL when the column is omitted. For example, given the following table: CREATE TABLE [dbo].[Table1]( [id] [int] IDENTITY(1,1) NOT NULL, [col1] [nvarchar](50) NOT NULL, [col2] [nvarchar](50) NULL, CONSTRAINT [PK_Table1] PRIMARY KEY CLUSTERED ([id] ASC) ) GO ALTER TABLE [dbo].[Table1] ADD CONSTRAINT [DF_Table1_col1] DEFAULT ('DB default') FOR [col1] The following two statements will work: INSERT INTO Table1 (col1, col2) VALUES ('test value', '') INSERT INTO Table1 (col2) VALUES ('') In the second statement, the default value is used for col1. The problem I have is when using LINQ-to-SQL (L2S) with a table like this. I want to produce the same behavior, but I can't figure out how to make L2S do that. I want to be able to run the following code and have the first row get the value I specify and the second row get the default value from the database: var context = new DataClasses1DataContext(); var row1 = new Table1 { col1 = "test value", col2 = "" }; context.Table1s.InsertOnSubmit(row1); context.SubmitChanges(); var row2 = new Table1 { col2 = "" }; context.Table1s.InsertOnSubmit(row2); context.SubmitChanges(); If the Auto Generated Value property of col1 is False, the first row is created as desired, but the second row fails with a null error on col1. If Auto Generated Value is True, both rows are created with the default value from the database. I've tried various combinations of Auto Generated Value, Auto-Sync and Nullable, but nothing I've tried gives the behavior I want. L2S does not omit the column from the insert statement when no value is specified. Instead it does something like this: INSERT INTO Table1 (col1, col2) VALUES (null, '') ...which of course causes a null error on col1. Is there some way to get L2S to omit a column from the insert statement if no value is given? Or is there some other way to get the behavior I want? I need the default value at the database level because not all row inserts are done via L2S, and in some cases the default value is a little more complex than a hard coded value (e.g. creating the default based on another field) so I'd rather avoid duplicating that logic.

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