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• Design Patterns Recommendation for Filtering Option

  - by Tarik

  Hi people, I am thinking to create a filter object which filters and delete everything like html tags from a context. But I want it to be independent which means the design pattern I can apply will help me to add more filters in the future without effecting the current codes. I thought Abstract Factory but it seems it ain't gonna work out the way I want. So maybe builder but it looks same. I don't know I am kinda confused, some one please recommend me a design pattern which can solve my problem but before that let me elaborate the problem a little bit. Lets say I have a class which has Description field or property what ever. And I need filters which remove the things I want from this Description property. So whenever I apply the filter I can add more filter in underlying tier. So instead of re-touching the Description field, I can easily add more filters and all the filters will run for Description field and delete whatever they are supposed to delete from the Description context. I hope I could describe my problem. I think some of you ran into the same situation before. Thanks in advance...

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• Sync Vs. Async Sockets Performance in C#

  - by Michael Covelli

  Everything that I read about sockets in .NET says that the asynchronous pattern gives better performance (especially with the new SocketAsyncEventArgs which saves on the allocation). I think this makes sense if we're talking about a server with many client connections where its not possible to allocate one thread per connection. Then I can see the advantage of using the ThreadPool threads and getting async callbacks on them. But in my app, I'm the client and I just need to listen to one server sending market tick data over one tcp connection. Right now, I create a single thread, set the priority to Highest, and call Socket.Receive() with it. My thread blocks on this call and wakes up once new data arrives. If I were to switch this to an async pattern so that I get a callback when there's new data, I see two issues The threadpool threads will have default priority so it seems they will be strictly worse than my own thread which has Highest priority. I'll still have to send everything through a single thread at some point. Say that I get N callbacks at almost the same time on N different threadpool threads notifying me that there's new data. The N byte arrays that they deliver can't be processed on the threadpool threads because there's no guarantee that they represent N unique market data messages because TCP is stream based. I'll have to lock and put the bytes into an array anyway and signal some other thread that can process what's in the array. So I'm not sure what having N threadpool threads is buying me. Am I thinking about this wrong? Is there a reason to use the Async patter in my specific case of one client connected to one server?

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• Async.Parallel or Array.Parallel.Map ?

  - by gurteen2

  Hello- I'm trying to implement a pattern I read from Don Syme's blog (http://blogs.msdn.com/dsyme/archive/2010/01/09/async-and-parallel-design-patterns-in-f-parallelizing-cpu-and-i-o-computations.aspx) which suggests that there are opportunities for massive performance improvements from leveraging asynchronous I/O. I am currently trying to take a piece of code that "works" one way, using Array.Parallel.Map, and see if I can somehow achieve the same result using Async.Parallel, but I really don't understand Async.Parallel, and cannot get anything to work. I have a piece of code (simplified below to illustrate the point) that successfully retrieves an array of data for one cusip. (A price series, for example) let getStockData cusip = let D = DataProvider() let arr = D.GetPriceSeries(cusip) return arr let data = Array.Parallel.map (fun x -> getStockData x) stockCusips So this approach contructs an array of arrays, by making a connection over the internet to my data vendor for each stock (which could be as many as 3000) and returns me an array of arrays (1 per stock, with a price series for each one). I admittedly don't understand what goes on underneath Array.Parallel.map, but am wondering if this is a scenario where there are resources wasted under the hood, and it actually could be faster using asynchronous I/O? So to test this out, I have attempted to make this function using asyncs, and I think that the function below follows the pattern in Don Syme's article using the URLs, but it won't compile with "let!". let getStockDataAsync cusip = async { let D = DataProvider() let! arr = D.GetData(cusip) return arr } The error I get is: This expression was expected to have type Async<'a but here has type obj It compiles fine with "let" instead of "let!", but I had thought the whole point was that you need the exclamation point in order for the command to run without blocking a thread. So the first question really is, what's wrong with my syntax above, in getStockDataAsync, and then at a higher level, can anyone offer some additional insight about asychronous I/O and whether the scenario I have presented would benefit from it, making it potentially much, much faster than Array.Parallel.map? Thanks so much.

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• How to roll the log file on startup in logback

  - by Mike Q

  Hi all, I would like to configure logback to do the following. Log to a file Roll the file when it reaches 50MB Only keep 7 days worth of logs On startup always generate a new file (do a roll) I have it all working except for the last item, startup roll. Does anyone know how to achieve that? Here's the config... <appender name="File" class="ch.qos.logback.core.rolling.RollingFileAppender"> <layout class="ch.qos.logback.classic.PatternLayout"> <Pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg \(%file:%line\)%n</Pattern> </layout> <File>server.log</File> <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"> <FileNamePattern>server.%d{yyyy-MM-dd}.log</FileNamePattern> <!-- keep 7 days' worth of history --> <MaxHistory>7</MaxHistory> <TimeBasedFileNamingAndTriggeringPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP"> <MaxFileSize>50MB</MaxFileSize> </TimeBasedFileNamingAndTriggeringPolicy> </rollingPolicy> </appender>

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• Resources related to data-mining and gaming on social networks

  - by darren

  Hi all I'm interested in the problem of patterning mining among players of social networking games. For example detecting cheaters of a game, given a company's user database. So far I have been following the usual recipe for a data mining project: construct a data warehouse that aggregates significant information select a classifier, and train it with a subsectio of records from the warehouse validate classifier with another test set lather, rinse, repeat Surprisingly, I've found very little in this area regarding literature, best practices, etc. I am hoping to crowdsource the information gathering problem here. Specifically what I'm looking for: What classifiers have worked will for this type of pattern mining (it seems highly temporal, users playing games, users receiving rewards, users transferring prizes etc). Are there any highly agreed upon attributes specific to social networking / gaming data? What is a practical amount of information that should be considered? One problem I've run into is data overload, where queries and data cleansing may take days to complete. Related to point above, what hardware resources are required to produce results? I've found it difficult to estimate the amount of computing power I will require for production use. It has become apparent that a white box in the corner does not have enough horse-power for such a project. Are companies generally resorting to cloud solutions? Are they buying clusters? Basically, any resources (theoretical, academic, or practical) about implementing a social networking / gaming pattern-mining program would be very much appreciated. Thanks.

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• AS3 : RegExp exec method in loop problem

  - by Boun

  Hi everyone, I need some help about RegExp in AS3. I have a simple pattern : patternYouTube = new RegExp ( "v(?:\/|=)([A-Z0-9_-]+)", "gi" ); This pattern is looking for the youTube id video. For example : var tmpUrl : String; var result : Object; var toto : Array = new Array(); toto = [http://www.youtube.com/v/J-vCxmjCm-8&autoplay=1, http://www.youtube.com/v/xFTRnE1WBmU&autoplay=1]; var i : uint; for ( i = 0 ; i < toto.length ; i++) { tmpUrl = toto[i]; result = patternYouTube.exec ( tmpUrl ); if ( result.length != 0 && result != null ) { trace(result); } } When i == 0, it works perfectly. Flash returns me : v/J-vCxmjCm-8,J-vCxmjCm-8 When i == 1, it fails. Flash returns me : null When I revert the two strings in my array such as : toto = [ http://www.youtube.com/v/xFTRnE1WBmU&autoplay=1, http://www.youtube.com/v/J-vCxmjCm-8&autoplay=1 ]; When i == 0, it works perfectly : Flash returns me : xFTRnE1WBmU When i == 1, it fails : Flash returns me : null Do you have any idea about the problem in the loop ?

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• Need help modifying C++ application to accept continuous piped input in Linux

  - by GreeenGuru

  The goal is to mine packet headers for URLs visited using tcpdump. So far, I can save a packet header to a file using: tcpdump "dst port 80 and tcp[13] & 0x08 = 8" -A -s 300 | tee -a ./Desktop/packets.txt And I've written a program to parse through the header and extract the URL when given the following command: cat ~/Desktop/packets.txt | ./packet-parser.exe But what I want to be able to do is pipe tcpdump directly into my program, which will then log the data: tcpdump "dst port 80 and tcp[13] & 0x08 = 8" -A -s 300 | ./packet-parser.exe Here is the script as it is. The question is: how do I need to change it to support continuous input from tcpdump? #include <boost/regex.hpp> #include <fstream> #include <cstdio> // Needed to define ios::app #include <string> #include <iostream> int main() { // Make sure to open the file in append mode std::ofstream file_out("/var/local/GreeenLogger/url.log", std::ios::app); if (not file_out) std::perror("/var/local/GreeenLogger/url.log"); else { std::string text; // Get multiple lines of input -- raw std::getline(std::cin, text, '\0'); const boost::regex pattern("GET (\\S+) HTTP.*?[\\r\\n]+Host: (\\S+)"); boost::smatch match_object; bool match = boost::regex_search(text, match_object, pattern); if(match) { std::string output; output = match_object[2] + match_object[1]; file_out << output << '\n'; std::cout << output << std::endl; } file_out.close(); } } Thank you ahead of time for the help!

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• Database structure - is mySQL the right choice?

  - by Industrial

  Hi everyone, We are currently planning the database structure of a quite complex e-commerce web app that has flexibility as it's main cornerstone. Our app features a large amount of data (products) and we have run into a slight headache trying to keep performance high without compromizing normalization rules in the database, or leaving our highly beloved flexibility concept behind when integrating product options (also widely known as product attributes or parameters). Based on various references and sources available, we have made up lists on pros and cons of all major and well known database patterns to solve this. After comparing these, we have come up with two final alternatives: EAV (Entity-attribute-value model) : Pros: Database is used for all sorting. Cons: All related queries will include a number of joins between multiple tables in order to complete the collection of data. SLOB (Serialized LOB, also known as Facade?) : Pros: Very flexible. Keeping the number of necessary joins low compared to a EAV design pattern. Easy to update/add/remove data from each product. Cons: All sorting will be done by the application instead of the database. Will use lots of performance (memory?) when big datasets is processed by a large number of users. Our main questions: Which pattern/structure would you use, or maybe even a different solution? Is there better databases besides mySQL available nowadays to accomplish what we want? Thanks a lot! Reference: http://stackoverflow.com/questions/695752/product-table-many-kinds-of-product-each-product-has-many-parameters

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• CCNet: "Failing Tasks : FilteredSourceControl: CheckForModifications" error

  - by Marc

  I've installed CCNet and now I'm trying to set up a link to our repository. When I visit the CCNet dashboard website the project shows up ok, but when I click the Force button I receive this error in the messages column: Failing Tasks : FilteredSourceControl: CheckForModifications If I log into the server as the account which I've specified CCNet should use to connect to the repository, and do an Update on the project by hand (i.e. using SVN.exe or TortoiseSVN) the update works fine. My sourcecontrol section of the CCNet.config file is below. <sourcecontrol type="filtered"> <sourceControlProvider type="svn" autoGetSource="true"> <executable>E:\SVNServer\bin\svn.exe</executable> <trunkUrl> https://bserver.int:4443/trunk </trunkUrl> <workingDirectory>E:\buildserver</workingDirectory> <username>USER</username> <password>PASSWORD</password> </sourceControlProvider> <inclusionFilters> <pathFilter> <pattern>**/*.*</pattern> </pathFilter> </inclusionFilters> </sourcecontrol> Both the cruisecontrol.net website and google seem utterly devoid of any information on this error, other than that it probably relates to the inclusionfilter section in the block above. Can anyone provide any ideas?

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• Am I deleting this properly?

  - by atch

  I have some struct: struct A { const char* name_; A* left_; A* right_; A(const char* name):name_(name), left_(nullptr), right_(nullptr){} A(const A&); //A(const A*);//ToDo A& operator=(const A&); ~A() { /*ToDo*/ }; }; /*Just to compile*/ A& A::operator=(const A& pattern) { //check for self-assignment if (this != &pattern) { void* p = new char[sizeof(A)]; } return *this; } A::A(const A& pat) { void* p = new char[sizeof(A)]; A* tmp = new (p) A("tmp"); tmp->~A(); delete tmp;//I WONDER IF HERE I SHOULD USE DIFFERENT delete[]? } int _tmain(int argc, _TCHAR* argv[]) { A a("a"); A b = a; cin.get(); return 0; } Guys I know this is far from ideal and far from finished. But please don't tell me the answer how to do it properly. I'm trying to figure it out myself. The only think I would like to know if I'm deleting my memory in proper way. Thanks.

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• How do you capture a group with regex?

  - by Sylvain

  Hi, I'm trying to extract a string from another using regex. I'm using the POSIX regex functions (regcomp, regexec ...), and I fail at capturing a group ... For instance, let the pattern be something as simple as "MAIL FROM:<(.*)>" (with REG_EXTENDED cflags) I want to capture everything between '<' and '' My problem is that regmatch_t gives me the boundaries of the whole pattern (MAIL FROM:<...) instead of just what's between the parenthesis ... What am I missing ? Thanks in advance, edit: some code #define SENDER_REGEX "MAIL FROM:<(.*)>" int main(int ac, char **av) { regex_t regex; int status; regmatch_t pmatch[1]; if (regcomp(&regex, SENDER_REGEX, REG_ICASE|REG_EXTENDED) != 0) printf("regcomp error\n"); status = regexec(&regex, av[1], 1, pmatch, 0); regfree(&regex); if (!status) printf( "matched from %d (%c) to %d (%c)\n" , pmatch[0].rm_so , av[1][pmatch[0].rm_so] , pmatch[0].rm_eo , av[1][pmatch[0].rm_eo] ); return (0); } outputs: $./a.out "012345MAIL FROM:<abcd>$" matched from 6 (M) to 22 ($) solution: as RarrRarrRarr said, the indices are indeed in pmatch[1].rm_so and pmatch[1].rm_eo hence regmatch_t pmatch[1]; becomes regmatch_t pmatch[2]; and regexec(&regex, av[1], 1, pmatch, 0); becomes regexec(&regex, av[1], 2, pmatch, 0); Thanks :)

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• How to avoid using this in a contructor

  - by Paralife

  I have this situation: interface MessageListener { void onMessageReceipt(Message message); } class MessageReceiver { MessageListener listener; public MessageReceiver(MessageListener listener, other arguments...) { this.listener = listener; } loop() { Message message = nextMessage(); listener.onMessageReceipt(message); } } and I want to avoid the following pattern: (Using the this in the Client constructor) class Client implements MessageListener { MessageReceiver receiver; MessageSender sender; public Client(...) { receiver = new MessageReceiver(this, other arguments...); sender = new Sender(...); } . . . @Override public void onMessageReceipt(Message message) { if(Message.isGood()) sender.send("Congrtulations"); else sender.send("Boooooooo"); } } The reason why i need the above functionality is because i want to call the sender inside the onMessageReceipt() function, for example to send a reply. But I dont want to pass the sender into a listener, so the only way I can think of is containing the sender in a class that implements the listener, hence the above resulting Client implementation. Is there a way to achive this without the use of 'this' in the constructor? It feels bizare and i dont like it, since i am passing myself to an object(MessageReceiver) before I am fully constructed. On the other hand, the MessageReceiver is not passed from outside, it is constructed inside, but does this 'purifies' the bizarre pattern? I am seeking for an alternative or an assurance of some kind that this is safe, or situations on which it might backfire on me.

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• Sync Vs. Async Sockets Performance in .NET

  - by Michael Covelli

  Everything that I read about sockets in .NET says that the asynchronous pattern gives better performance (especially with the new SocketAsyncEventArgs which saves on the allocation). I think this makes sense if we're talking about a server with many client connections where its not possible to allocate one thread per connection. Then I can see the advantage of using the ThreadPool threads and getting async callbacks on them. But in my app, I'm the client and I just need to listen to one server sending market tick data over one tcp connection. Right now, I create a single thread, set the priority to Highest, and call Socket.Receive() with it. My thread blocks on this call and wakes up once new data arrives. If I were to switch this to an async pattern so that I get a callback when there's new data, I see two issues The threadpool threads will have default priority so it seems they will be strictly worse than my own thread which has Highest priority. I'll still have to send everything through a single thread at some point. Say that I get N callbacks at almost the same time on N different threadpool threads notifying me that there's new data. The N byte arrays that they deliver can't be processed on the threadpool threads because there's no guarantee that they represent N unique market data messages because TCP is stream based. I'll have to lock and put the bytes into an array anyway and signal some other thread that can process what's in the array. So I'm not sure what having N threadpool threads is buying me. Am I thinking about this wrong? Is there a reason to use the Async patter in my specific case of one client connected to one server?

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• java regex: capture multiline sequence between tokens

  - by Guillaume

  I'm struggling with regex for splitting logs files into log sequence in order to match pattern inside these sequences. log format is: timestamp fieldA fieldB fieldn log message1 timestamp fieldA fieldB fieldn log message2 log message2bis timestamp fieldA fieldB fieldn log message3 The timestamp regex is known. I want to extract every log sequence (potentialy multiline) between timestamps. And I want to keep the timestamp. I want in the same time to keep the exact count of lines. What I need is how to decorate timestamp pattern to make it split my log file in log sequence. I can not split the whole file as a String, since the file content is provided in a CharBuffer Here is sample method that will be using this log sequence matcher: private void matches(File f, CharBuffer cb) { Matcher sequenceBreak = sequencePattern.matcher(cb); // sequence matcher int lines = 1; int sequences = 0; while (sequenceBreak.find()) { sequences++; String sequence = sequenceBreak.group(); if (filter.accept(sequence)) { System.out.println(f + ":" + lines + ":" + sequence); } //count lines Matcher lineBreak = LINE_PATTERN.matcher(sequence); while (lineBreak.find()) { lines++; } if (sequenceBreak.end() == cb.limit()) { break; } } }

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• Django deployment - can't import app.urls

  - by hora

  I just moved a django project to a deployment server from my dev server, and I'm having some issues deploying it. My apache config is as follows: <Location "/"> Order allow,deny Allow from all SetHandler python-program PythonHandler django.core.handlers.modpython SetEnv DJANGO_SETTINGS_MODULE project.settings PythonDebug On PythonPath "['/home/django/'] + sys.path" </Location> Django does work, since it renders the Django debug views, but I get the following error: ImportError at / No module named app.urls And here is all the information Django gives me: Request Method: GET Request URL: http://myserver.com/ Django Version: 1.1.1 Python Version: 2.6.5 Installed Applications: ['django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.sites', 'django.contrib.admin', 'django.contrib.admindocs', 'project.app'] Installed Middleware: ('django.middleware.common.CommonMiddleware', 'django.contrib.sessions.middleware.SessionMiddleware', 'django.contrib.auth.middleware.AuthenticationMiddleware') Traceback: File "/usr/lib64/python2.6/site-packages/django/core/handlers/base.py" in get_response 83. request.path_info) File "/usr/lib64/python2.6/site-packages/django/core/urlresolvers.py" in resolve 218. sub_match = pattern.resolve(new_path) File "/usr/lib64/python2.6/site-packages/django/core/urlresolvers.py" in resolve 216. for pattern in self.url_patterns: File "/usr/lib64/python2.6/site-packages/django/core/urlresolvers.py" in _get_url_patterns 245. patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module) File "/usr/lib64/python2.6/site-packages/django/core/urlresolvers.py" in _get_urlconf_module 240. self._urlconf_module = import_module(self.urlconf_name) File "/usr/lib64/python2.6/site-packages/django/utils/importlib.py" in import_module 35. __import__(name) Exception Type: ImportError at / Exception Value: No module named app.urls Any ideas as to why I get an import error?

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• Question about functional OOP style in JavaScript

  - by valums

  I prefer to use functional OOP style for my code (similar to the module pattern) because it helps me to avoid the "new" keyword and all problems with the scope of "this" keyword in callbacks. But I've run into a few minor issues with it. I would like to use the following code to create a class. namespace.myClass = function(){ var self = {}, somePrivateVar1; // initialization code that would call // private or public methods privateMethod(); self.publicMethod(); // sorry, error here function privateMethod(){} self.publicMethod = function(){}; return self; } The problem is that I can't call public methods from my initialization code, as these functions are not defined yet. The obvious solution would be to create an init method, and call it before "return self" line. But maybe you know a more elegant solution? Also, how do you usually handle inheritance with this pattern? I use the following code, butI would like to hear your ideas and suggestions. namespace.myClass2 = function(){ var self = namespace.parentClass(), somePrivateVar1; var superMethod = self.someMethod; self.someMethod = function(){ // example shows how to overwrite parent methods superMethod(); }; return self; } Edit. For those who asked what are the reasons for choosing this style of OOP, you can look into following questions: http://stackoverflow.com/questions/1557386/prototypal-vs-functional-oop-in-javascript http://stackoverflow.com/questions/383402/is-javascript-s-new-keyword-considered-harmful

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• Changing FileNames using RegEx and Recursion

  - by yeahumok

  Hello I'm trying to rename files that my program lists as having "illegal characters" for a SharePoint file importation. The illegal characters I am referring to are: ~ # % & * {} / \ | : < ? - "" What i'm trying to do is recurse through the drive, gather up a list of filenames and then through Regular Expressions, pick out file names from a List and try to replace the invalid characters in the actual filenames themselves. Anybody have any idea how to do this? So far i have this: (please remember, i'm a complete n00b to this stuff) class Program { static void Main(string[] args) { string[] files = Directory.GetFiles(@"C:\Documents and Settings\bob.smith\Desktop\~Test Folder for [SharePoint] %testing", "*.*", SearchOption.AllDirectories); foreach (string file in files) { Console.Write(file + "\r\n"); } Console.WriteLine("Press any key to continue..."); Console.ReadKey(true); string pattern = " *[\\~#%&*{}/:<>?|\"-]+ *"; string replacement = " "; Regex regEx = new Regex(pattern); string[] fileDrive = Directory.GetFiles(@"C:\Documents and Settings\bob.smith\Desktop\~Test Folder for [SharePoint] %testing", "*.*", SearchOption.AllDirectories); StreamWriter sw = new StreamWriter(@"C:\Documents and Settings\bob.smith\Desktop\~Test Folder for [SharePoint] %testing\File_Renames.txt"); foreach(string fileNames in fileDrive) { string sanitized = regEx.Replace(fileNames, replacement); sw.Write(sanitized + "\r\n"); } sw.Close(); } } So what i need to figure out is how to recursively search for these invalid chars, replace them in the actual filename itself. Anybody have any ideas?

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• How do I extract HTML content using Regex in PHP

  - by gAMBOOKa

  I know, i know... regex is not the best way to extract HTML text. But I need to extract article text from a lot of pages, I can store regexes in the database for each website. I'm not sure how XML parsers would work with multiple websites. You'd need a separate function for each website. In any case, I don't know much about regexes, so bear with me. I've got an HTML page in a format similar to this <html> <head>...</head> <body> <div class=nav>...</div><p id="someshit" /> <div class=body>....</div> <div class=footer>...</div> </body> I need to extract the contents of the body class container. I tried this. $pattern = "/<div class=\"body\">\(.*?\)<\/div>/sui" $text = $htmlPageAsIs; if (preg_match($pattern, $text, $matches)) echo "MATCHED!"; else echo "Sorry gambooka, but your text is in another castle."; What am I doing wrong? My text ends up in another castle.

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• Using LINQ in generic collections

  - by Hugo S Ferreira

  Hi, Please consider the following snippet from an implementation of the Interpreter pattern: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<string>; return (list != null) ? list.FirstOrDefault() : null; } What about if I want to use the same function for integers? public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<string>; if (list != null) return list.FirstOrDefault(); var list = ctx as IEnumerable<int>; return (list != null) ? list.FirstOrDefault() : null; } What I wanted was something like: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable; return (list != null) ? list.FirstOrDefault() : null; } But Linq doesn't act on IEnumerables. Instead, to get to this solution, I would be forced to write something like: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable; if (list != null) foreach(var i in list) { yield return i; return; } return null; } Or use a generic method: public override T Execute<T>(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<T>; return (list != null) ? list.FirstOrDefault() : null; } Which would break the Interpreter pattern (as it was implemented in this system). Covariance would also fail (at least in C#3), though would it work, it would be the exact behavior I wanted: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<object>; return (list != null) ? list.FirstOrDefault() : null; } So, my question is: what's the best way to achieve the intended behavior? Thanks :-)

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• Groovlet not working in GWT project, container : embedded Jetty in google plugin

  - by user325284

  Hi, I am working on a GWT application which uses GWT-RPC. I just made a test groovlet to see if it worked, but ran into some problems here's my groovlet package groovy.servlet; print "testing the groovlet"; Every tutorial said we don't need to subclass anything, and just a simple script would act as a servlet. my web.xml looks like this - <!-- groovy --> <servlet> <servlet-name>testGroovy</servlet-name> <servlet-class>groovy.servlet.testGroovy</servlet-class> </servlet> <servlet-mapping> <servlet-name>testGroovy</servlet-name> <url-pattern>*.groovy</url-pattern> </servlet-mapping When I Run as - web application, i get the following error from jetty : [WARN] failed testGroovy javax.servlet.UnavailableException: Servlet class groovy.servlet.testGroovy is not a javax.servlet.Servlet at org.mortbay.jetty.servlet.ServletHolder.checkServletType(ServletHolder.java:377) at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:234) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39) at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:616) at org.mortbay.jetty.servlet.Context.startContext(Context.java:140) at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1220) at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:513) at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:448) at com.google.gwt.dev.shell.jetty.JettyLauncher$WebAppContextWithReload.doStart(JettyLauncher.java:447) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39) at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130) at org.mortbay.jetty.handler.RequestLogHandler.doStart(RequestLogHandler.java:115) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39) at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130) at org.mortbay.jetty.Server.doStart(Server.java:222) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39) at com.google.gwt.dev.shell.jetty.JettyLauncher.start(JettyLauncher.java:543) at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:421) at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:1035) at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:783) at com.google.gwt.dev.DevMode.main(DevMode.java:275) What did I miss ?

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• Objective-C Simple Inheritance and OO Principles

  - by bleeckerj

  I have a subclass SubClass that inherits from baseclass BaseClass. BaseClass has an initializer, like so: -(id)init { self = [super init]; if(self) { [self commonInit]; } return self; } -(void)commonInit { self.goodStuff = [[NSMutableArray alloc]init]; } SubClass does its initializer, like so: -(id)init { self = [super init]; if(self) { [self commonInit]; } return self; } -(void)commonInit { self.extraGoodStuff = [[NSMutableArray alloc]init]; } Now, I've *never taken a proper Objective-C course, but I'm a programmer more from the Electrical Engineering side, so I make do. I've developed server-side applications mostly in Java though, so I may be seeing the OO world through Java principles. When SubClass is initialized, it calls the BaseClass init and my expectation would be — because inheritance to me implies that characteristics of a BaseClass pass through to SubClass — that the commonInit method in BaseClass would be called during BaseClass init. It is not. I can *sorta understand maybe-possibly-stretch-my-imagination why it wouldn't be. But, then — why wouldn't it be based on the principles of OOP? What does "self" represent if not the instance of the class of the running code? Okay, so — I'm not going to argue that what a well-developed edition of Objective-C is doing is wrong. So, then — what is the pattern I should be using in this case? I want SubClass to have two main bits — the goodStuff that BaseClass has as well as the extraGoodStuff that it deserves as well. Clearly, I've been using the wrong pattern in this type of situation. Am I meant to expose commonInit (which makes me wonder about encapsulation principles — why expose something that, in the Java world at least, would be considered "protected" and something that should only ever be called once for each instance)? I've run into a similar problem in the recent past and tried to muddle through it, but now — I'm really wondering if I've got my principles and concepts all straight in my head. Little help, please.

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• Groovlet + Tomcat: "unable to resolve class" when importing libraries

  - by Rob Hruska

  I'm having some trouble running a groovy servlet (groovlet) in tomcat that imports a library class. When I don't import anything the groovlet works correctly, but if I do import something that I expect to be on the classpath (I can import the same class successfully in a regular servlet), I see the following error: groovy.util.ScriptException: Could not parse scriptName: /MyGroovlet.groovy java.lang.RuntimeException: groovy.util.ScriptException: Could not parse scriptName: /MyGroovlet.groovy at groovy.servlet.GroovyServlet$1.call(GroovyServlet.java:123) ... Caused by: org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed, /MyGroovlet.groovy: 1: unable to resolve class com.mycompany.mypackage.MyLibraryClass @ line 1, column 1. The jar containing MyLibraryClass is in shared/lib, which is loaded by tomcat by the following in catalina.properties: shared.loader=...,${catalina.base}/shared/lib/*.jar,... My groovlets are mapped as described in the user guide in my application's web.xml: <servlet> <servlet-name>GroovyServlet</servlet-name> <servlet-class>groovy.servlet.GroovyServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>GroovyServlet</servlet-name> <url-pattern>*.groovy</url-pattern> </servlet-mapping> And here's the code for the groovlet, MyGroovlet.groovy: import com.mycompany.mypackage.MyLibraryClass MyLibraryClass.someStaticMethod() My groovlet is deployed to WEB-INF/groovy/MyGroovlet.groovy, per the GroovyServlet API. When I visit http://localhost:8080/myapplication/MyGroovlet.groovy, the error described previously is written to my application logs. Is there some way that I need to explicitly declare the runtime classpath for GroovyServlet? I've tried moving the library jar to several places, including WEB-INF/lib and moving the actual MyLibraryClass.class file to WEB-INF/classes, but with no luck.

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• ASP.NET MVC and NHibernate coupling

  - by Ben

  I have just started learning NHibernate. Over the past few months I have been using IoC / DI (structuremap) and the repository pattern and it has made my applications much more loosely coupled and easier to test. When switching my persistence layer to NHibernate I decided to stick with my repositories. Currently I am creating a new session on each method call but of course this means that I can not benefit from lazy loading. Therefore I wish to implement session-per-request but in doing so this will make my web project dependent on NHibernate (perhaps this is not such a bad thing?). I was planning to inject ISession into my repositories and create and dispose sessions on beginrequest/endrequest events (see http://ayende.com/Blog/archive/2009/08/05/do-you-need-a-framework.aspx) Is this a good approach? Presumably I cannot use session-per-request without having a reference to NHibernate in my web project? Having the web project dependent on NHibernate prompts my next (few) questions - why even bother with the repository? Since my web app is calling services that talk to the repositories, why not ditch the repositories and just add my NHibernate persistance code inside the services? And finally, is there really any need to split out into so many projects. Is a web project and an infrastructure project sufficient? I realise that I have veered off a bit from my original question but it seems that everyone seems to have their own opinion on these topics. Some people use the repository pattern with NHibernate, some don't. Some people stick their mapping files with the related classes, others have a separate project for this. Many thanks, Ben

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• GWT, MVP, and UIBinding - How to get the best of all worlds

  - by Stephane Grenier

  With MVP, you normally bind the View (UI) with the Presenter in the Presenter. However with the latest version of GWT, especially with UIBinding, you can do the following in the View: @UiHandler("loginButton") void onAboutClicked(ClickEvent event) { // my login code } Which basically exchanges a lot of anonymous inner class code for some quick annotation code. Very nice!! The problem is that this code is in the view and not the presenter... So I thought maybe: @UiHandler("loginButton") void onAboutClicked(ClickEvent event) { myPresenter.onAboutClicked(...); } But there are several problems with this approach. The most important, you blur the lines between View and Presenter. Who does which binding, in some cases it's the View, in others it's the presenter (binding to events not in your current view but that need to be attached - for example a system wide update event). You still get the benefit of being able to unit test your presenter, but at what cost. The responsibilities are messy now. For example the binding is sometimes in the View and others times in the Presenter level. I can see the code falling into all kinds of chaos with time. I also thought of extending the Presenter to the View, so that you could do this in the View. The problem here is that you lose the Presenter's ability to run standard unit tests! That's a major issue. That and the lines again become blurred. So my question, does anyone have a good method of taking advantage of the annotation from UIBinding within the MVP pattern without blurring the lines and losing the advantages of the MVP pattern?

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• How do you configure jax-ws to work with Spring using jax-ws commons?

  - by LES2

  In web.xml I have the following: <servlet> <description>JAX-WS endpoint - EARM</description> <display-name>jaxws-servlet</display-name> <servlet-name>jaxws-servlet</servlet-name> <servlet-class>com.sun.xml.ws.transport.http.servlet.WSSpringServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>jaxws-servlet</servlet-name> <url-pattern>/webServices/*</url-pattern> </servlet-mapping> In my application context I have the following definitions: <bean id="helloService" class="com.foo.HelloServiceImpl"> <property name="regularService" ref="regularService" /> </bean> <wss:binding url="/webServices/helloService" service="#helloService" /> I get a NullPointerException when trying to access the WSDL: java.lang.NullPointerException at com.sun.xml.ws.transport.http.HttpAdapter.<init>(HttpAdapter.java:145) at com.sun.xml.ws.transport.http.servlet.ServletAdapter.<init>(ServletAdapter.java:76) at com.sun.xml.ws.transport.http.servlet.ServletAdapterList.createHttpAdapter(ServletAdapterList.java:5 0) at com.sun.xml.ws.transport.http.servlet.ServletAdapterList.createHttpAdapter(ServletAdapterList.java:4 7) at com.sun.xml.ws.transport.http.HttpAdapterList.createAdapter(HttpAdapterList.java:73) at com.sun.xml.ws.transport.http.servlet.SpringBinding.create(SpringBinding.java:24) at com.sun.xml.ws.transport.http.servlet.WSSpringServlet.init(WSSpringServlet.java:46) Strange ... appears to be a configuration error but the darn thing just dies with a NullPointerException!!!!!!!! No logging is provided. Deployed in Resin.

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