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• Multiple "pages" in GWT with human friendly URLs

  - by Andreas Borglin

  Hi. I'm playing with a GWT/GAE project which will have three different "pages", although it is not really pages in a GWT sense. The top views (one for each page) will have completely different layouts, but some of the widgets will be shared. One of the pages is the main page which is loaded by the default url (http://www.site.com), but the other two needs additional URL information to differentiate the page type. They also need a name parameter, (like http://www.site.com/project/project-name. There are at least two solutions to this that I'm aware of. Use GWT history mechanism and let page type and parameters (such as project name) be part of the history token. Use servlets with url-mapping patterns (like /project/*) The first choice might seem obvious at first, but it has several drawbacks. First, a user should be able to easily remember and type URL directly to a project. It is hard to produce a human friendly URL with history tokens. Second, I'm using gwt-presenter and this approach would mean that we need to support subplaces in one token, which I'd rather avoid. Third, a user will typically stay at one page, so it makes more sense that the page information is part of the "static" URL. Using servlets solves all these problems, but also creates other ones. So my first questions is, what is the best solution here? If I would go for the servlet solution, new questions pop up. It might make sense to split the GWT app into three separate modules, each with an entry point. Each servlet that is mapped to a certain page would then simply forward the request to the GWT module that handles that page. Since a user typically stays at one page, the browser only needs to load the js for that page. Based on what I've read, this solution is not really recommended. I could also stick with one module, but then GWT needs to find out which page it should display. It could either query the server or parse the URL itself. If I stick with one GWT module, I need to keep the page information stored on server side. Naturally I thought about sessions, but I'm not sure if its a good idea to mix page information with user data. A session usually lives between user login and logout, but in this case it would need different behavior. Would it be bad practise to handle this via sessions? The one GWT module + servlet solution also leads to another problem. If a user goes from a project page to the main page, how will GWT know that this has happened? The app will not be reloaded, so it will be treated as a simple state change. It seems rather ineffecient to have to check page info for every state change. Anyone care to guide me out of the foggy darkness that surrounds me? :-)

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• Django manager for _set in model

  - by Daniel Johansson

  Hello, I'm in the progress of learning Django at the moment but I can't figure out how to solve this problem on my own. I'm reading the book Developers Library - Python Web Development With Django and in one chapter you build a simple CMS system with two models (Story and Category), some generic and custom views together with templates for the views. The book only contains code for listing stories, story details and search. I wanted to expand on that and build a page with nested lists for categories and stories. - Category1 -- Story1 -- Story2 - Category2 - Story3 etc. I managed to figure out how to add my own generic object_list view for the category listing. My problem is that the Story model have STATUS_CHOICES if the Story is public or not and a custom manager that'll only fetch the public Stories per default. I can't figure out how to tell my generic Category list view to also use a custom manager and only fetch the public Stories. Everything works except that small problem. I'm able to create a list for all categories with a sub list for all stories in that category on a single page, the only problem is that the list contains non public Stories. I don't know if I'm on the right track here. My urls.py contains a generic view that fetches all Category objects and in my template I'm using the *category.story_set.all* to get all Story objects for that category, wich I then loop over. I think it would be possible to add a if statement in the template and use the VIEWABLE_STATUS from my model file to check if it should be listed or not. The problem with that solution is that it's not very DRY compatible. Is it possible to add some kind of manager for the Category model too that only will fetch in public Story objects when using the story_set on a category? Or is this the wrong way to attack my problem? Related code urls.py (only category list view): urlpatterns += patterns('django.views.generic.list_detail', url(r'^categories/$', 'object_list', {'queryset': Category.objects.all(), 'template_object_name': 'category' }, name='cms-categories'), models.py: from markdown import markdown import datetime from django.db import models from django.db.models import permalink from django.contrib.auth.models import User VIEWABLE_STATUS = [3, 4] class ViewableManager(models.Manager): def get_query_set(self): default_queryset = super(ViewableManager, self).get_query_set() return default_queryset.filter(status__in=VIEWABLE_STATUS) class Category(models.Model): """A content category""" label = models.CharField(blank=True, max_length=50) slug = models.SlugField() class Meta: verbose_name_plural = "categories" def __unicode__(self): return self.label @permalink def get_absolute_url(self): return ('cms-category', (), {'slug': self.slug}) class Story(models.Model): """A hunk of content for our site, generally corresponding to a page""" STATUS_CHOICES = ( (1, "Needs Edit"), (2, "Needs Approval"), (3, "Published"), (4, "Archived"), ) title = models.CharField(max_length=100) slug = models.SlugField() category = models.ForeignKey(Category) markdown_content = models.TextField() html_content = models.TextField(editable=False) owner = models.ForeignKey(User) status = models.IntegerField(choices=STATUS_CHOICES, default=1) created = models.DateTimeField(default=datetime.datetime.now) modified = models.DateTimeField(default=datetime.datetime.now) class Meta: ordering = ['modified'] verbose_name_plural = "stories" def __unicode__(self): return self.title @permalink def get_absolute_url(self): return ("cms-story", (), {'slug': self.slug}) def save(self): self.html_content = markdown(self.markdown_content) self.modified = datetime.datetime.now() super(Story, self).save() admin_objects = models.Manager() objects = ViewableManager() category_list.html (related template): {% extends "cms/base.html" %} {% block content %} <h1>Categories</h1> {% if category_list %} <ul id="category-list"> {% for category in category_list %} <li><a href="{{ category.get_absolute_url }}">{{ category.label }}</a></li> {% if category.story_set %} <ul> {% for story in category.story_set.all %} <li><a href="{{ story.get_absolute_url }}">{{ story.title }}</a></li> {% endfor %} </ul> {% endif %} {% endfor %} </ul> {% else %} <p> Sorry, no categories at the moment. </p> {% endif %} {% endblock %}

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• Psychology researcher wants to learn new language

  - by user273347

  I'm currently considering R, matlab, or python, but I'm open to other options. Could you help me pick the best language for my needs? Here are the criteria I have in mind (not in order): Simple to learn. I don't really have a lot of free time, so I'm looking for something that isn't extremely complicated and/or difficult to pick up. I know some C, FWIW. Good for statistics/psychometrics. I do a ton of statistics and psychometrics analysis. A lot of it is basic stuff that I can do with SPSS, but I'd like to play around with the more advanced stuff too (bootstrapping, genetic programming, data mining, neural nets, modeling, etc). I'm looking for a language/environment that can help me run my simpler analyses faster and give me more options than a canned stat package like SPSS. If it can even make tables for me, then it'll be perfect. I also do a fair bit of experimental psychology. I use a canned experiment "programming" software (SuperLab) to make most of my experiments, but I want to be able to program executable programs that I can run on any computer and that can compile the data from the experiments in a spreadsheet. I know python has psychopy and pyepl and matlab has psychtoolbox, but I don't know which one is best. If R had something like this, I'd probably be sold on R already. I'm looking for something regularly used in academe and industry. Everybody else here (including myself, so far) uses canned stat and experiment programming software. One of the reasons I'm trying to learn a programming language is so that I can keep up when I move to another lab. Looking forward to your comments and suggestions. Thank you all for your kind and informative replies. I appreciate it. It's still a tough choice because of so many strong arguments for each language. Python - Thinking about it, I've forgotten so much about C already (I don't even remember what to do with an array) that it might be better for me to start from scratch with a simple program that does what it's supposed to do. It looks like it can do most of the things I'll need it to do, though not as cleanly as R and MATLAB. R - I'm really liking what I'm reading about R. The packages are perfect for my statistical work now. Given the purpose of R, I don't think it's suited to building psychological experiments though. To clarify, what I mean is making a program that presents visual and auditory stimuli to my specifications (hundreds of them in a preset and/or randomized sequence) and records the response data gathered from participants. MATLAB - It's awesome that cognitive and neuro folk are recommending MATLAB, because I'm preparing for the big leap from social and personality psychology to cognitive neuro. The problem is the Uni where I work doesn't have MATLAB licenses (and 3750 GBP for a compiler license is not an option for me haha). Octave looks like a good alternative. PsychToolbox is compatible with Octave, thankfully. SQL - Thanks for the tip. I'll explore that option, too. Python will be the least backbreaking and most useful in the short term. R is well suited to my current work. MATLAB is well suited to my prospective work. It's a tough call, but I think I am now equipped to make a more well-informed decision about where to go next. Thanks again!

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• multiple-inheritance substitution

  - by Luigi

  I want to write a module (framework specific), that would wrap and extend Facebook PHP-sdk (https://github.com/facebook/php-sdk/). My problem is - how to organize classes, in a nice way. So getting into details - Facebook PHP-sdk consists of two classes: BaseFacebook - abstract class with all the stuff sdk does Facebook - extends BaseFacebook, and implements parent abstract persistance-related methods with default session usage Now I have some functionality to add: Facebook class substitution, integrated with framework session class shorthand methods, that run api calls, I use mostly (through BaseFacebook::api()), authorization methods, so i don't have to rewrite this logic every time, configuration, sucked up from framework classes, insted of passed as params caching, integrated with framework cache module I know something has gone very wrong, because I have too much inheritance that doesn't look very normal.Wrapping everything in one "complex extension" class also seems too much. I think I should have few working togheter classes - but i get into problems like: if cache class doesn't really extend and override BaseFacebook::api() method - shorthand and authentication classes won't be able to use the caching. Maybe some kind of a pattern would be right in here? How would you organize these classes and their dependencies? EDIT 04.07.2012 Bits of code, related to the topic: This is how the base class of Facebook PHP-sdk: abstract class BaseFacebook { // ... some methods public function api(/* polymorphic */) { // ... method, that makes api calls } public function getUser() { // ... tries to get user id from session } // ... other methods abstract protected function setPersistentData($key, $value); abstract protected function getPersistentData($key, $default = false); // ... few more abstract methods } Normaly Facebook class extends it, and impelements those abstract methods. I replaced it with my substitude - Facebook_Session class: class Facebook_Session extends BaseFacebook { protected function setPersistentData($key, $value) { // ... method body } protected function getPersistentData($key, $default = false) { // ... method body } // ... implementation of other abstract functions from BaseFacebook } Ok, then I extend this more with shorthand methods and configuration variables: class Facebook_Custom extends Facebook_Session { public funtion __construct() { // ... call parent's constructor with parameters from framework config } public function api_batch() { // ... a wrapper for parent's api() method return $this->api('/?batch=' . json_encode($calls), 'POST'); } public function redirect_to_auth_dialog() { // method body } // ... more methods like this, for common queries / authorization } I'm not sure, if this isn't too much for a single class ( authorization / shorthand methods / configuration). Then there comes another extending layer - cache: class Facebook_Cache extends Facebook_Custom { public function api() { $cache_file_identifier = $this->getUser(); if(/* cache_file_identifier is not null and found a valid file with cached query result */) { // return the result } else { try { // call Facebook_Custom::api, cache and return the result } catch(FacebookApiException $e) { // if Access Token is expired force refreshing it parent::redirect_to_auth_dialog(); } } } // .. some other stuff related to caching } Now this pretty much works. New instance of Facebook_Cache gives me all the functionality. Shorthand methods from Facebook_Custom use caching, because Facebook_Cache overwrited api() method. But here is what is bothering me: I think it's too much inheritance. It's all very tight coupled - like look how i had to specify 'Facebook_Custom::api' instead of 'parent:api', to avoid api() method loop on Facebook_Cache class extending. Overall mess and ugliness. So again, this works but I'm just asking about patterns / ways of doing this in a cleaner and smarter way.

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• Accessing Python module fails although its package is imported

  - by codethief

  Hey Stackers! :) My Django project's directory hierarchy looks like this: + pybsd |---+ devices |---+ templates |---+ views |---+ interaction |---- __init__.py |---- geraete.py |---- geraetemodelle.py |---- geraetegruppen.py |---- __init__.py |---- ajax.py |---- html.py |---- misc.py |---- __init__.py |---- urls.py |---- __init__.py |---- urls.py (Please excuse the German names. I preferred not to replace them here since it would add yet another possible error source when trying out the solutions you'll hopefully suggest and answering your questions.) Every request to http://URL/devices/.* is dispatched to the urls.py file living in /devices: # ... from views import html, ajax, misc, interaction urlpatterns = patterns('', # ... (r'^ajax/update/(?P<table>[a-z_]+)$', ajax.update), (r'^ajax/delete/(?P<table>[a-z_]+)$', ajax.delete), (r'^ajax/select_options/(?P<table>[a-z_]+)$', ajax.select_options), (r'^interaction/geraete/info/(?P<geraet>\d+)$', interaction.geraete.info), (r'^interaction/geraete/delete/(?P<geraet>\d+)?$', interaction.geraete.delete), (r'^interaction/geraetemodelle/delete/(?P<geraetemodell>\d+)?$', interaction.geraetemodelle.delete), (r'^interaction/geraetegruppen/delete/(?P<geraetegruppe>\d+)?$', interaction.geraetegruppen.delete), # ... ) All URL definitions work except for those referencing the interaction package. I'm constantly getting the following error: File "/home/simon/projekte/pybsd/../pybsd/devices/urls.py", line 33, in `<module>` (r'^interaction/geraete/info/(?P<geraet>\d+)$', interaction.geraete.info), AttributeError: 'module' object has no attribute 'geraete' I double-checked that the __init__.py files don't contain anything. Maybe you've already found the (Python- or Django-related?) mistake I made and am apparently unable to see. If not, read on. In any case, thanks for reading this long post! Isolating the problem 1st test It works if I provide the view functions as strings: (r'^interaction/geraete/info/(?P<geraet>\d+)$', 'devices.views.interaction.geraete.info'), (r'^interaction/geraete/delete/(?P<geraet>\d+)?$', 'devices.views.interaction.geraete.delete'), (r'^interaction/geraetemodelle/delete/(?P<geraetemodell>\d+)?$', 'devices.views.interaction.geraetemodelle.delete'), (r'^interaction/geraetegruppen/delete/(?P<geraetegruppe>\d+)?$', 'devices.views.interaction.geraetegruppen.delete'), ... or add yet another line to the imports: from views.interaction import geraete, geraetemodelle, geraetegruppen Using from views.interaction import *, however, doesn't work either and results in the same error message. 2nd test I created a file test.py in /devices: from views import interaction print dir(interaction) Output: simon@bsd-simon:~/projekte/pybsd/devices$ python test.py ['__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__'] Again, no sign of the modules I created in the interaction package (geraete.py, geraetemodelle.py, geraetegruppen.py). Unlike in urls.py, trying from view.interaction import geraete, geraetegruppen, geraetemodelle in test.py results in ImportError: No module named view.interaction this time. 3rd test I started the Django shell: $ python manage.py shell >>> import devices.views.interaction.geraete >>> dir(devices.views.interaction.geraete) ['Abteilung', 'Auftrag', 'Auftragsvorlage', 'Geraet', 'Geraetegruppe', 'Geraetemodell', 'HttpResponse', 'HttpResponseBadRequest', 'HttpResponseRedirect', 'Raum', 'Standort', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'delete', 'info', 'models', 'move', 'render_to_response'] >>> $ python manage.py shell >>> from devices.views.interaction import geraete >>> dir(geraete) ['Abteilung', 'Auftrag', 'Auftragsvorlage', 'Geraet', 'Geraetegruppe', 'Geraetemodell', 'HttpResponse', 'HttpResponseBadRequest', 'HttpResponseRedirect', 'Raum', 'Standort', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'delete', 'info', 'models', 'move', 'render_to_response'] >>> $ python manage.py shell >>> import devices.views.interaction >>> devices.views.interaction.geraete Traceback (most recent call last): File "<console>", line 1, in <module> AttributeError: 'module' object has no attribute 'geraete' >>> dir(devices.views.interaction) ['__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__']

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• Performance in backpropagation algorithm

  - by Taban

  I've written a matlab program for standard backpropagation algorithm, it is my homework and I should not use matlab toolbox, so I write the entire code by myself. This link helped me for backpropagation algorithm. I have a data set of 40 random number and initial weights randomly. As output, I want to see a diagram that shows the performance. I used mse and plot function to see performance for 20 epochs but the result is this: I heard that performance should go up through backpropagation, so I want to know is there any problem with my code or this result is normal because local minimums. This is my code: Hidden_node=inputdlg('Enter the number of Hidden nodes'); a=0.5;%initialize learning rate hiddenn=str2num(Hidden_node{1,1}); randn('seed',0); %creating data set s=2; N=10; m=[5 -5 5 5;-5 -5 5 -5]; S = s*eye(2); [l,c] = size(m); x = []; % Creating the training set for i = 1:c x = [x mvnrnd(m(:,i)',S,N)']; end % target value toutput=[ones(1,N) zeros(1,N) ones(1,N) zeros(1,N)]; for epoch=1:20; %number of epochs for kk=1:40; %number of patterns %initial weights of hidden layer for ii=1 : 2; for jj=1 :hiddenn; whidden{ii,jj}=rand(1); end end initial the wights of output layer for ii=1 : hiddenn; woutput{ii,1}=rand(1); end for ii=1:hiddenn; x1=x(1,kk); x2=x(2,kk); w1=whidden{1,ii}; w2=whidden{2,ii}; activation{1,ii}=(x1(1,1)*w1(1,1))+(x2(1,1)*w2(1,1)); end %calculate output of hidden nodes for ii=1:hiddenn; hidden_to_out{1,ii}=logsig(activation{1,ii}); end activation_O{1,1}=0; for jj=1:hiddenn; activation_O{1,1} = activation_O{1,1}+(hidden_to_out{1,jj}*woutput{jj,1}); end %calculate output out{1,1}=logsig(activation_O{1,1}); out_for_plot(1,kk)= out{1,ii}; %calculate error for output node delta_out{1,1}=(toutput(1,kk)-out{1,1}); %update weight of output node for ii=1:hiddenn; woutput{ii,jj}=woutput{ii,jj}+delta_out{1,jj}*hidden_to_out{1,ii}*dlogsig(activation_O{1,jj},logsig(activation_O{1,jj}))*a; end %calculate error of hidden nodes for ii=1:hiddenn; delta_hidden{1,ii}=woutput{ii,1}*delta_out{1,1}; end %update weight of hidden nodes for ii=1:hiddenn; for jj=1:2; whidden{jj,ii}= whidden{jj,ii}+(delta_hidden{1,ii}*dlogsig(activation{1,ii},logsig(activation{1,ii}))*x(jj,kk)*a); end end a=a/(1.1);%decrease learning rate end %calculate performance e=toutput(1,kk)-out_for_plot(1,1); perf(1,epoch)=mse(e); end plot(perf); Thanks a lot.

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• LLVM JIT segfaults. What am I doing wrong?

  - by bugspy.net

  It is probably something basic because I am just starting to learn LLVM.. The following creates a factorial function and tries to git and execute it (I know the generated func is correct because I was able to static compile and execute it). But I get segmentation fault upon execution of the function (in EE-runFunction(TheF, Args)) #include <iostream> #include "llvm/Module.h" #include "llvm/Function.h" #include "llvm/PassManager.h" #include "llvm/CallingConv.h" #include "llvm/Analysis/Verifier.h" #include "llvm/Assembly/PrintModulePass.h" #include "llvm/Support/IRBuilder.h" #include "llvm/Support/raw_ostream.h" #include "llvm/ExecutionEngine/JIT.h" #include "llvm/ExecutionEngine/GenericValue.h" using namespace llvm; Module* makeLLVMModule() { // Module Construction LLVMContext& ctx = getGlobalContext(); Module* mod = new Module("test", ctx); Constant* c = mod->getOrInsertFunction("fact64", /*ret type*/ IntegerType::get(ctx,64), IntegerType::get(ctx,64), /*varargs terminated with null*/ NULL); Function* fact64 = cast<Function>(c); fact64->setCallingConv(CallingConv::C); /* Arg names */ Function::arg_iterator args = fact64->arg_begin(); Value* x = args++; x->setName("x"); /* Body */ BasicBlock* block = BasicBlock::Create(ctx, "entry", fact64); BasicBlock* xLessThan2Block= BasicBlock::Create(ctx, "xlst2_block", fact64); BasicBlock* elseBlock = BasicBlock::Create(ctx, "else_block", fact64); IRBuilder<> builder(block); Value *One = ConstantInt::get(Type::getInt64Ty(ctx), 1); Value *Two = ConstantInt::get(Type::getInt64Ty(ctx), 2); Value* xLessThan2 = builder.CreateICmpULT(x, Two, "tmp"); //builder.CreateCondBr(xLessThan2, xLessThan2Block, cond_false_2); builder.CreateCondBr(xLessThan2, xLessThan2Block, elseBlock); /* Recursion */ builder.SetInsertPoint(elseBlock); Value* xMinus1 = builder.CreateSub(x, One, "tmp"); std::vector<Value*> args1; args1.push_back(xMinus1); Value* recur_1 = builder.CreateCall(fact64, args1.begin(), args1.end(), "tmp"); Value* retVal = builder.CreateBinOp(Instruction::Mul, x, recur_1, "tmp"); builder.CreateRet(retVal); /* x<2 */ builder.SetInsertPoint(xLessThan2Block); builder.CreateRet(One); return mod; } int main(int argc, char**argv) { long long x; if(argc > 1) x = atol(argv[1]); else x = 4; Module* Mod = makeLLVMModule(); verifyModule(*Mod, PrintMessageAction); PassManager PM; PM.add(createPrintModulePass(&outs())); PM.run(*Mod); // Now we going to create JIT ExecutionEngine *EE = EngineBuilder(Mod).create(); // Call the function with argument x: std::vector<GenericValue> Args(1); Args[0].IntVal = APInt(64, x); Function* TheF = cast<Function>(Mod->getFunction("fact64")) ; /* The following CRASHES.. */ GenericValue GV = EE->runFunction(TheF, Args); outs() << "Result: " << GV.IntVal << "\n"; delete Mod; return 0; }

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• Managing highly repetitive code and documentation in Java

  - by polygenelubricants

  Highly repetitive code is generally a bad thing, and there are design patterns that can help minimize this. However, sometimes it's simply inevitable due to the constraints of the language itself. Take the following example from java.util.Arrays: /** * Assigns the specified long value to each element of the specified * range of the specified array of longs. The range to be filled * extends from index <tt>fromIndex</tt>, inclusive, to index * <tt>toIndex</tt>, exclusive. (If <tt>fromIndex==toIndex</tt>, the * range to be filled is empty.) * * @param a the array to be filled * @param fromIndex the index of the first element (inclusive) to be * filled with the specified value * @param toIndex the index of the last element (exclusive) to be * filled with the specified value * @param val the value to be stored in all elements of the array * @throws IllegalArgumentException if <tt>fromIndex &gt; toIndex</tt> * @throws ArrayIndexOutOfBoundsException if <tt>fromIndex &lt; 0</tt> or * <tt>toIndex &gt; a.length</tt> */ public static void fill(long[] a, int fromIndex, int toIndex, long val) { rangeCheck(a.length, fromIndex, toIndex); for (int i=fromIndex; i<toIndex; i++) a[i] = val; } The above snippet appears in the source code 8 times, with very little variation in the documentation/method signature but exactly the same method body, one for each of the root array types int[], short[], char[], byte[], boolean[], double[], float[], and Object[]. I believe that unless one resorts to reflection (which is an entirely different subject in itself), this repetition is inevitable. I understand that as a utility class, such high concentration of repetitive Java code is highly atypical, but even with the best practice, repetition does happen! Refactoring doesn't always work because it's not always possible (the obvious case is when the repetition is in the documentation). Obviously maintaining this source code is a nightmare. A slight typo in the documentation, or a minor bug in the implementation, is multiplied by however many repetitions was made. In fact, the best example happens to involve this exact class: Google Research Blog - Extra, Extra - Read All About It: Nearly All Binary Searches and Mergesorts are Broken (by Joshua Bloch, Software Engineer) The bug is a surprisingly subtle one, occurring in what many thought to be just a simple and straightforward algorithm. // int mid =(low + high) / 2; // the bug int mid = (low + high) >>> 1; // the fix The above line appears 11 times in the source code! So my questions are: How are these kinds of repetitive Java code/documentation handled in practice? How are they developed, maintained, and tested? Do you start with "the original", and make it as mature as possible, and then copy and paste as necessary and hope you didn't make a mistake? And if you did make a mistake in the original, then just fix it everywhere, unless you're comfortable with deleting the copies and repeating the whole replication process? And you apply this same process for the testing code as well? Would Java benefit from some sort of limited-use source code preprocessing for this kind of thing? Perhaps Sun has their own preprocessor to help write, maintain, document and test these kind of repetitive library code? A comment requested another example, so I pulled this one from Google Collections: com.google.common.base.Predicates lines 276-310 (AndPredicate) vs lines 312-346 (OrPredicate). The source for these two classes are identical, except for: AndPredicate vs OrPredicate (each appears 5 times in its class) "And(" vs Or(" (in the respective toString() methods) #and vs #or (in the @see Javadoc comments) true vs false (in apply; ! can be rewritten out of the expression) -1 /* all bits on */ vs 0 /* all bits off */ in hashCode() &= vs |= in hashCode()

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• Tomcat stops responding to JK requests

  - by Bruno Reis

  Hello. I have a nasty issue with load-balanced Tomcat servers that are hanging up. Any help would be greatly appreciated. The system I'm running Tomcat 6.0.26 on HotSpot Server 14.3-b01 (Java 1.6.0_17-b04) on three servers sitting behind another server that acts as load balancer. The load balancer runs Apache (2.2.8-1) + MOD_JK (1.2.25). All of the servers are running Ubuntu 8.04. The Tomcat's have 2 connectors configured: an AJP one, and a HTTP one. The AJP is to be used with the load balancer, while the HTTP is used by the dev team to directly connect to a chosen server (if we have a reason to do so). I have Lambda Probe 1.7b installed on the Tomcat servers to help me diagnose and fix the problem soon to be described. The problem Here's the problem: after about 1 day the application servers are up, JK Status Manager starts reporting status ERR for, say, Tomcat2. It will simply get stuck on this state, and the only fix I've found so far is to ssh the box and restart Tomcat. I must also mention that JK Status Manager takes a lot longer to refresh when there's a Tomcat server in this state. Finally, the "Busy" count of the stuck Tomcat on JK Status Manager is always high, and won't go down per se -- I must restart the Tomcat server, wait, then reset the worker on JK. Analysis Since I have 2 connectors on each Tomcat (AJP and HTTP), I still can connect to the application through the HTTP one. The application works just fine like this, very, very fast. That is perfectly normal, since I'm the only one using this server (as JK stopped delegating requests to this Tomcat). To try to better understand the problem, I've taken a thread dump from a Tomcat which is not responding anymore, and from another one that has been restarted recently (say, 1 hour before). The instance that is responding normally to JK shows most of the TP-ProcessorXXX threads in "Runnable" state, with the following stack trace: java.net.SocketInputStream.socketRead0 ( native code ) java.net.SocketInputStream.read ( SocketInputStream.java:129 ) java.io.BufferedInputStream.fill ( BufferedInputStream.java:218 ) java.io.BufferedInputStream.read1 ( BufferedInputStream.java:258 ) java.io.BufferedInputStream.read ( BufferedInputStream.java:317 ) org.apache.jk.common.ChannelSocket.read ( ChannelSocket.java:621 ) org.apache.jk.common.ChannelSocket.receive ( ChannelSocket.java:559 ) org.apache.jk.common.ChannelSocket.processConnection ( ChannelSocket.java:686 ) org.apache.jk.common.ChannelSocket$SocketConnection.runIt ( ChannelSocket.java:891 ) org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run ( ThreadPool.java:690 ) java.lang.Thread.run ( Thread.java:619 ) The instance that is stuck show most (all?) of the TP-ProcessorXXX threads in "Waiting" state. These have the following stack trace: java.lang.Object.wait ( native code ) java.lang.Object.wait ( Object.java:485 ) org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run ( ThreadPool.java:662 ) java.lang.Thread.run ( Thread.java:619 ) I don't know of the internals of Tomcat, but I would infer that the "Waiting" threads are simply threads sitting on a thread pool. So, if they are threads waiting inside of a thread pool, why wouldn't Tomcat put them to work on processing requests from JK? Solution? So, as I've stated before, the only fix I've found is to stop the Tomcat instance, stop the JK worker, wait the latter's busy count slowly go down, start Tomcat again, and enable the JK worker once again. What is causing this problem? How should I further investigate it? What can I do to solve it? Thanks in advance.

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• Reading email address from contacts fails with weird memory issue - Solved

  - by CapsicumDreams

  Hi all, I'm stumped. I'm trying to get a list of all the email address a person has. I'm using the ABPeoplePickerNavigationController to select the person, which all seems fine. I'm setting my ABRecordRef personDealingWith; from the person argument to - (BOOL)peoplePickerNavigationController:(ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)person property:(ABPropertyID)property identifier:(ABMultiValueIdentifier)identifier { and everything seems fine up till this point. The first time the following code executes, all is well. When subsequently run, I can get issues. First, the code: // following line seems to make the difference (issue 1) // NSLog(@"%d", ABMultiValueGetCount(ABRecordCopyValue(personDealingWith, kABPersonEmailProperty))); // construct array of emails ABMultiValueRef multi = ABRecordCopyValue(personDealingWith, kABPersonEmailProperty); CFIndex emailCount = ABMultiValueGetCount(multi); if (emailCount > 0) { // collect all emails in array for (CFIndex i = 0; i < emailCount; i++) { CFStringRef emailRef = ABMultiValueCopyValueAtIndex(multi, i); [emailArray addObject:(NSString *)emailRef]; CFRelease(emailRef); } } // following line also matters (issue 2) CFRelease(multi); If compiled as written, the are no errors or static analysis problems. This crashes with a *** -[Not A Type retain]: message sent to deallocated instance 0x4e9dc60 error. But wait, there's more! I can fix it in either of two ways. Firstly, I can uncomment the NSLog at the top of the function. I get a leak from the NSLog's ABRecordCopyValue every time through, but the code seems to run fine. Also, I can comment out the CFRelease(multi); at the end, which does exactly the same thing. Static compilation errors, but running code. So without a leak, this function crashes. To prevent a crash, I need to haemorrhage memory. Neither is a great solution. Can anyone point out what's going on? Solution: It turned out that I wasn't storing the ABRecordRef personDealingWith var correctly. I'm still not sure how to do that properly, but instead of having the functionality in another routine (performed later), I'm now doing the grunt-work in the delegate method, and using the derived results at my leisure. The new (working) routine: - (BOOL)peoplePickerNavigationController:(ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)person { // as soon as they select someone, return personDealingWithFullName = (NSString *)ABRecordCopyCompositeName(person); personDealingWithFirstName = (NSString *)ABRecordCopyValue(person, kABPersonFirstNameProperty); // construct array of emails [personDealingWithEmails removeAllObjects]; ABMutableMultiValueRef multi = ABRecordCopyValue(person, kABPersonEmailProperty); if (ABMultiValueGetCount(multi) > 0) { // collect all emails in array for (CFIndex i = 0; i < ABMultiValueGetCount(multi); i++) { CFStringRef emailRef = ABMultiValueCopyValueAtIndex(multi, i); [personDealingWithEmails addObject:(NSString *)emailRef]; CFRelease(emailRef); } } CFRelease(multi); return NO; }

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• Postmortem debugging with WinDBG.

  - by Drazar

  I have an WCF-service running on an server, and occasionally(1-2 times every month) it throws an COMException with the informative message ”Unknown error (0x8005008)”. When i googled for this particular error I only got threads about problems when creating virtual directories in IIS. And the source code hasn’t anything with making a virtual directory in IIS. DirectoryServiceLib.LdapProvider.Directory - CreatePost - Could not create employee for 195001010000,000000000000: System.Runtime.InteropServices.COMException (0x80005008): Unknown error (0x80005008) at System.DirectoryServices.PropertyValueCollection.PopulateList I've taken a memorydump when I catch the Exception for further analysis in WinDBG. After switching to the right thread I executed the !CLRStack command: 000000001b8ab6d8 000000007708671a [NDirectMethodFrameStandalone: 000000001b8ab6d8] Common.MemoryDump.MiniDumpWriteDump(IntPtr, Int32, IntPtr, MINIDUMP_TYPE, IntPtr, IntPtr, IntPtr) 000000001b8ab680 000007ff002808d8 DomainBoundILStubClass.IL_STUB_PInvoke(IntPtr, Int32, IntPtr, MINIDUMP_TYPE, IntPtr, IntPtr, IntPtr) 000000001b8ab780 000007ff00280812 Common.MemoryDump.CreateMiniDump(System.String) 000000001b8ab7e0 000007ff0027b218 DirectoryServiceLib.LdapProvider.Directory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String) 000000001b8ad6d8 000007fef8816869 [HelperMethodFrame: 000000001b8ad6d8] 000000001b8ad820 000007feec2b6c6f System.DirectoryServices.PropertyValueCollection.PopulateList() 000000001b8ad860 000007feec225f0f System.DirectoryServices.PropertyValueCollection..ctor(System.DirectoryServices.DirectoryEntry, System.String) 000000001b8ad8a0 000007feec22d023 System.DirectoryServices.PropertyCollection.get_Item(System.String) 000000001b8ad8f0 000007ff00274d34 Common.DirectoryEntryExtension.GetStringAttribute(System.String) 000000001b8ad940 000007ff0027f507 DirectoryServiceLib.LdapProvider.DirectoryPost.Copy(DirectoryServiceLib.LdapProvider.DirectoryPost) 000000001b8ad980 000007ff0027a7cf DirectoryServiceLib.LdapProvider.Directory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String) 000000001b8adbe0 000007ff00279532 DirectoryServiceLib.WCFDirectory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String) 000000001b8adc60 000007ff001f47bd DynamicClass.SyncInvokeCreatePost(System.Object, System.Object[], System.Object[]) My conclusion is that it fails when the code is calling System.DirectoryServices.PropertyCollection.get_Item(System.String). So after issuing an !CLRStack -a I get this result: 000000001b8ad8a0 000007feec22d023 System.DirectoryServices.PropertyCollection.get_Item(System.String) PARAMETERS: this = <no data> propertyName = <no data> LOCALS: <CLR reg> = 0x0000000001dcef78 <no data> My very first question is why does it display no data on the propertyname? I am kinda new on Windbg. However I executed an dumpobject on = 0x0000000001dcef78: 0:013> !do 0x0000000001dcef78 Name: System.String MethodTable: 000007fef66d6960 EEClass: 000007fef625eec8 Size: 74(0x4a) bytes File: C:\Windows\Microsoft.Net\assembly\GAC_64\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll String: personalprescriptioncode Fields: MT Field Offset Type VT Attr Value Name 000007fef66dc848 40000ed 8 System.Int32 1 instance 24 m_stringLength 000007fef66db388 40000ee c System.Char 1 instance 70 m_firstChar 000007fef66d6960 40000ef 10 System.String 0 shared static Empty >> Domain:Value 0000000000174e10:00000000019d1420 000000001a886f50:00000000019d1420 << So when the source code wants to fetch the personalprescriptioncode from Active Directory(what is used for persistence layer) it fails. Looking back at the stack it is when issuing the Copy method. DirectoryServiceLib.LdapProvider.DirectoryPost.Copy(DirectoryServiceLib.LdapProvider.DirectoryPost) So looking in the sourcecode: DirectoryPost postInLimbo = DirectoryPostFactory.Instance().GetDirectoryPost(LdapConfigReader.Instance().GetConfigValue("LimboDN"), idGenPerson.ID.UserId); if (postInLimbo != null) newPost.Copy(postInLimbo); This code is looking for another post in OU=limbo with the same UserId and if it finds one it copies the attributes to the new post. In this case it does and it fails with personalprescriptioncode. I've looked in Active Directory under OU=Limbo and the post exist there with the attribute personalprescriptioncode=31243. Question 1: Why does it display no data for some of the PARAMETERS and LOCALS? Is it the GC who has cleaned up before the memorydump had been created. Question 2: Is there anymore i can do to get to the solution to this problem?

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• Thread Synchronisation 101

  - by taspeotis

  Previously I've written some very simple multithreaded code, and I've always been aware that at any time there could be a context switch right in the middle of what I'm doing, so I've always guarded access the shared variables through a CCriticalSection class that enters the critical section on construction and leaves it on destruction. I know this is fairly aggressive and I enter and leave critical sections quite frequently and sometimes egregiously (e.g. at the start of a function when I could put the CCriticalSection inside a tighter code block) but my code doesn't crash and it runs fast enough. At work my multithreaded code needs to be a tighter, only locking/synchronising at the lowest level needed. At work I was trying to debug some multithreaded code, and I came across this: EnterCriticalSection(&m_Crit4); m_bSomeVariable = true; LeaveCriticalSection(&m_Crit4); Now, m_bSomeVariable is a Win32 BOOL (not volatile), which as far as I know is defined to be an int, and on x86 reading and writing these values is a single instruction, and since context switches occur on an instruction boundary then there's no need for synchronising this operation with a critical section. I did some more research online to see whether this operation did not need synchronisation, and I came up with two scenarios it did: The CPU implements out of order execution or the second thread is running on a different core and the updated value is not written into RAM for the other core to see; and The int is not 4-byte aligned. I believe number 1 can be solved using the "volatile" keyword. In VS2005 and later the C++ compiler surrounds access to this variable using memory barriers, ensuring that the variable is always completely written/read to the main system memory before using it. Number 2 I cannot verify, I don't know why the byte alignment would make a difference. I don't know the x86 instruction set, but does mov need to be given a 4-byte aligned address? If not do you need to use a combination of instructions? That would introduce the problem. So... QUESTION 1: Does using the "volatile" keyword (implicity using memory barriers and hinting to the compiler not to optimise this code) absolve a programmer from the need to synchronise a 4-byte/8-byte on x86/x64 variable between read/write operations? QUESTION 2: Is there the explicit requirement that the variable be 4-byte/8-byte aligned? I did some more digging into our code and the variables defined in the class: class CExample { private: CRITICAL_SECTION m_Crit1; // Protects variable a CRITICAL_SECTION m_Crit2; // Protects variable b CRITICAL_SECTION m_Crit3; // Protects variable c CRITICAL_SECTION m_Crit4; // Protects variable d // ... }; Now, to me this seems excessive. I thought critical sections synchronised threads between a process, so if you've got one you can enter it and no other thread in that process can execute. There is no need for a critical section for each variable you want to protect, if you're in a critical section then nothing else can interrupt you. I think the only thing that can change the variables from outside a critical section is if the process shares a memory page with another process (can you do that?) and the other process starts to change the values. Mutexes would also help here, named mutexes are shared across processes, or only processes of the same name? QUESTION 3: Is my analysis of critical sections correct, and should this code be rewritten to use mutexes? I have had a look at other synchronisation objects (semaphores and spinlocks), are they better suited here? QUESTION 4: Where are critical sections/mutexes/semaphores/spinlocks best suited? That is, which synchronisation problem should they be applied to. Is there a vast performance penalty for choosing one over the other? And while we're on it, I read that spinlocks should not be used in a single-core multithreaded environment, only a multi-core multithreaded environment. So, QUESTION 5: Is this wrong, or if not, why is it right? Thanks in advance for any responses :)

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• OSGI Declarative Services (DS): What is a good way of using service component instances

  - by Christoph

  I am just getting started with OSGI and Declarative Services (DS) using Equinox and Eclipse PDE. I have 2 Bundles, A and B. Bundle A exposes a component which is consumed by Bundle B. Both bundles also expose this service to the OSGI Service registry again. Everything works fine so far and Equinox is wireing the components together, which means the Bundle A and Bundle B are instanciated by Equinox (by calling the default constructor) and then the wireing happens using the bind / unbind methods. Now, as Equinox is creating the instances of those components / services I would like to know what is the best way of getting this instance? So assume there is third class class which is NOT instantiated by OSGI: Class WantsToUseComponentB{ public void doSomethingWithComponentB(){ // how do I get componentB??? Something like this maybe? ComponentB component = (ComponentB)someComponentRegistry.getComponent(ComponentB.class.getName()); } I see the following options right now: 1. Use a ServiceTracker in the Activator to get the Service of ComponentBundleA.class.getName() (I have tried that already and it works, but it seems to much overhead to me) and make it available via a static factory methods public class Activator{ private static ServiceTracker componentBServiceTracker; public void start(BundleContext context){ componentBServiceTracker = new ServiceTracker(context, ComponentB.class.getName(),null); } public static ComponentB getComponentB(){ return (ComponentB)componentBServiceTracker.getService(); }; } 2. Create some kind of Registry where each component registers as soon as the activate() method is called. public ComponentB{ public void bind(ComponentA componentA){ someRegistry.registerComponent(this); } or public ComponentB{ public void activate(ComponentContext context){ someRegistry.registerComponent(this); } } } 3. Use an existing registry inside osgi / equinox which has those instances? I mean OSGI is already creating instances and wires them together, so it has the objects already somewhere. But where? How can I get them? Conclusion Where does the class WantsToUseComponentB (which is NOT a Component and NOT instantiated by OSGI) get an instance of ComponentB from? Are there any patterns or best practises? As I said I managed to use a ServiceTracker in the Activator, but I thought that would be possible without it. What I am looking for is actually something like the BeanContainer of Springframework, where I can just say something like Container.getBean(ComponentA.BEAN_NAME). But I don't want to use Spring DS. I hope that was clear enough. Otherwise I can also post some source code to explain in more detail. Thanks Christoph UPDATED: Answer to Neil's comment: Thanks for clarifying this question against the original version, but I think you still need to state why the third class cannot be created via something like DS. Hmm don't know. Maybe there is a way but I would need to refactor my whole framework to be based on DS, so that there are no "new MyThirdClass(arg1, arg2)" statements anymore. Don't really know how to do that, but I read something about ComponentFactories in DS. So instead of doing a MyThirdClass object = new MyThirdClass(arg1, arg2); I might do a ComponentFactory myThirdClassFactory = myThirdClassServiceTracker.getService(); // returns a if (myThirdClassFactory != null){ MyThirdClass object = objectFactory.newInstance(); object.setArg1("arg1"); object.setArg2("arg2"); } else{ // here I can assume that some service of ComponentA or B went away so MyThirdClass Componenent cannot be created as there are missing dependencies? } At the time of writing I don't know exactly how to use the ComponentFactories but this is supposed to be some kind of pseudo code :) Thanks Christoph

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• jqgrid retrieving empty rows using webapi (REST)

  - by polonskyg

  I'm using jqgrid in an ASPNET MVC4 project with WebApi (REST), Entity Framework 5 using Unit Of Work and Repository patterns. My problem is that I see the data flowing as json to the browser and I see three rows in the grid, but those rows are empty, and the data is not shown (three empty rows in the grid). This is method to get the data in the WebApi controller: public dynamic GetGridData(int rows, int page, string sidx, string sord) { var pageSize = rows; var index = sidx; var order = sord; var categories = Uow.Categories.GetAll().OrderBy(t => (string.IsNullOrEmpty(index) ? "Id" : index) + " " + (order ?? "desc")); var pageIndex = Convert.ToInt32(page) - 1; var totalRecords = categories.Count(); var totalPages = (int)Math.Ceiling((float) totalRecords / (float) pageSize); var categoriesPage = categories.Skip(pageIndex * pageSize).Take(pageSize).ToList(); return new { total = totalPages, page = page, records = totalRecords, rows = (from category in categoriesPage select new { id = category.Id.ToString(), cell = new string[] { category.Id.ToString(), category.Name, category.Description } }).ToArray() }; } This is the json received in the browser { "total": 1, "page": 1, "records": 3, "rows": [{ "id": "1", "cell": ["1", "Category 1", null] }, { "id": "3", "cell": ["3", "Category 3", "asAS"] }, { "id": "4", "cell": ["4", "Category 4", null] }] } This is the .js file with jqgrid jQuery("#ajaxGrid").jqGrid({ url: $("#ServiceUrl").val(), datatype: "json", jsonReader: { repeatitems: false, id: "Id" }, colNames: ['Id', 'Name', 'Description'], colModel: [ { name: 'id', editable: true, sortable: true, hidden: true, align: 'left' }, { name: 'name', editable: true, sortable: true, hidden: false, align: 'left' }, { name: 'description', editable: true, sortable: true, hidden: false, align: 'left' } ], mtype: 'GET', rowNum: 15, pager: '#ajaxGridPager', rowList: [10, 20, 50, 100], caption: 'List of Categories', imgpath: $("#ServiceImagesUrl").val(), altRows: true, shrinkToFit: true, viewrecords: true, autowidth: true, height: 'auto', error: function(x, e) { alert(x.readyState + " "+ x.status +" "+ e.msg); } }); function updateDialog(action) { return { url: $("#ServiceUrl").val(), closeAfterAdd: true, closeAfterEdit: true, afterShowForm: function (formId) { }, modal: true, onclickSubmit: function (params) { var list = $("#ajaxGrid"); var selectedRow = list.getGridParam("selrow"); params.url += "/" + list.getRowData(selectedRow).Id; params.mtype = action; }, width: "300", ajaxEditOptions: { contentType: "application/json" }, serializeEditData: function (data) { delete data.oper; return JSON.stringify(data); } }; } jQuery("#ajaxGrid").jqGrid( 'navGrid', '#ajaxGridPager', { add: true, edit: true, del: true, search: false, refresh: false }, updateDialog('PUT'), updateDialog('POST'), updateDialog('DELETE') ); BTW, If I want to return jqGridData instead the dynamic, How should I do it? Did is showing empty rows as well: public class jqGridData<T> where T : class { public int page { get; set; } public int records { get; set; } public IEnumerable<T> rows { get; set; } public decimal total { get; set; } } public jqGridData<Category> GetGridData(int rows, int page, string sidx, string sord) { var pageSize = rows; var index = sidx; var order = sord; var categories = Uow.Categories.GetAll().OrderBy(t => (string.IsNullOrEmpty(index) ? "Id" : index) + " " + (order ?? "desc")); var pageIndex = Convert.ToInt32(page) - 1; var totalRecords = categories.Count(); var totalPages = (int)Math.Ceiling((float)totalRecords / (float)pageSize); var categoriesPage = categories.Skip(pageIndex * pageSize).Take(pageSize); return new jqGridData<Category> { page = page, records = totalRecords, total = totalPages, rows = categoriesPage }; }

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• Is this a right way to use NHibernate?

  - by Venemo

  I spent the rest of the evening reading StackOverflow questions and also some blog entries and links about the subject. All of them turned out to be very helpful, but I still feel that they don't really answer my question. So, I'm developing a simple web application. I'd like to create a reusable data access layer which I can later reuse in other solutions. 99% of these will be web applications. This seems to be a good excuse for me to learn NHibernate and some of the patterns around it. My goals are the following: I don't want the business logic layer to know ANYTHING about the inner workings of the database, nor NHibernate itself. I want the business logic layer to have the least possible number of assumptions about the data access layer. I want the data access layer as simplistic and easy-to-use as possible. This is going to be a simple project, so I don't want to overcomplicate anything. I want the data access layer to be as non-intrusive as possible. Will all this in mind, I decided to use the popular repository pattern. I read about this subject on this site and on various dev blogs, and I heard some stuff about the unit of work pattern. I also looked around and checked out various implementations. (Including FubuMVC contrib, and SharpArchitecture, and stuff on some blogs.) I found out that most of these operate with the same principle: They create a "unit of work" which is instantiated when a repository is instantiated, they start a transaction, do stuff, and commit, and then start all over again. So, only one ISession per Repository and that's it. Then the client code needs to instantiate a repository, do stuff with it, and then dispose. This usage pattern doesn't meet my need of being as simplistic as possible, so I began thinking about something else. I found out that NHibernate already has something which makes custom "unit of work" implementations unnecessary, and that is the CurrentSessionContext class. If I configure the session context correctly, and do the clean up when necessary, I'm good to go. So, I came up with this: I have a static class called NHibernateHelper. Firstly, it has a static property called CurrentSessionFactory, which upon first call, instantiates a session factory and stores it in a static field. (One ISessionFactory per one AppDomain is good enough.) Then, more importantly, it has a CurrentSession static property, which checks if there is an ISession bound to the current session context, and if not, creates one, and binds it, and it returns with the ISession bound to the current session context. Because it will be used mostly with WebSessionContext (so, one ISession per HttpRequest, although for the unit tests, I configured ThreadStaticSessionContext), it should work seamlessly. And after creating and binding an ISession, it hooks an event handler to the HttpContext.Current.ApplicationInstance.EndRequest event, which takes care of cleaning up the ISession after the request ends. (Of course, it only does this if it is really running in a web environment.) So, with all this set up, the NHibernateHelper will always be able to return a valid ISession, so there is no need to instantiate a Repository instance for the "unit of work" to operate properly. Instead, the Repository is a static class which operates with the ISession from the NHibernateHelper.CurrentSession property, and exposes some functionality through that. I'm curious, what do you think about this? Is it a valid way of thinking, or am I completely off track here?

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• Rendering a Long Document on iPad

  - by benjismith

  I'm implementing a document viewer with highlighting/annotation capabilities for a custom document format on iPad. The documents are kind of long (100 to 200 pages, if printed on paper) and I've had a hard time finding the right approach. Here are the requirments: 1) Basic rich-text styling: control of left/right margins. Control of font name, size, foreground/background color, and line spacing. Bold, italics, underline, etc. 2) Selection and highlighting of arbitrary text regions (not limited to paragraph boundaries, like in Safari/UIWebView). 3) Customization of the Cut/Copy/Paste popup (what is that thing called anyhow? UIActionBar?) This is one of the essential requirements of the app. My first implementation was based on UIWebView. I just rendered the document as HTML with CSS for text styling. But I couldn't get the kind of text selection behavior I wanted (across paragraph boundaries) and the UIActionBar can't be customized from within UIWebView. So I started working on a javascript approach, faking the device text-selection behavior using JQuery to trap touch events and dynamically modifying the DOM to change the background color of selected regions of text. I built a fake UIActionBar control as a hidden DIV, positioning it and unhiding it whenever there was an active selection region. Not too shabby. The main problem is that it's SLOOOOOOOW. Scrolling through the document is nice and quick, but dynamically changing the DOM is not very snappy. Plus, I couldn't figure out how to recreate the magnifier loupe, so my fake text-selection GUI doesn't look quite the same as the native implementation. Also, I haven't yet implemented the communication bridge between the javascript layer and the objective-c layer (where the rest of the app lives), but it was shaping up to be a huge hassle. So I've been looking at CoreText, but there are precious few examples on the web. I spent a little time with this simple little demo: http://github.com/jonasschnelli/I7CoreTextExample/ It shows how to use CoreText to draw an NSAttributedText string into a UIView. But it has its own problems: It doesn't implement text-selection behavior, and it doesn't present a UIActionBar, so I don't have any idea how to make that happen. And, more importantly, it tries to draw the entire document all at once, with significant performance degradations for long documents. My documents can have thousands of paragraphs, and less than 1% of the document is ever on screen at a time. On the plus side, these documents already contain precise formatting information. I know the exact page-position of every line of text, so I don't need a layout engine. Does anyone know how to implement this sort of view using CoreText? I understand that a full-fledged implementation is overkill for a question like this, but I'm looking for a good CoreText example with a few basic requirements: 1) Precise layout & formatting control (using the formatting metrics and text styles I've already calculated). 2) Arbitrary selection of text. 3) Customization of the UIActionBar. 4) Efficient recycling of resources for off-screen objects. I'd be happy to implement my own recycling when text elements scroll off-screen, but wouldn't that require re-implementing UIScrollView? I'm brand-new to iPhone development, and still getting used to Objective-C, but I've been working in other languages (Java, C#, flex/actionscript, etc) for more than ten years, so I feel confident in my ability to get the work done, if only I had a better feel for the iPhone SDK and the common coding patterns for stuff like this. Is it just me, or does the SDK documentation really suck? Anyhow, thanks for your help!

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• Spring MVC working with Web Designers

  - by jboyd

  When working with web-designers in a Spring-MVC and JSP environment, are there any tools or helpful patterns to reduce the pain of going back and forth from HTML to JSP and back? Project requirements dictate that views will change often, and it can be difficult to make changes efficiently because of the amount of Java code that leaks into the view layer. Ideally I'd like to remove almost all Java code from the view, but it does not seem like this works with the Spring/JSP philosophy where often the way to remove Java code is to replace that code with tag libraries, which will still have a similar problem. To provide a little clarity to my question I'm going to include some existing code (inherited by me) to show the kinds of problems I'm likely to face when change the look of our views: <%-- Begin looping through results --%> <% List memberList = memberSearchResults.getResults(); for(int i = start - 1; i < memberList.size() && i < end; i++) { Profile profile = (Profile)memberList.get(i); long profileId = profile.getProfileId(); String nickname = profile.getNickname(); String description = profile.getDescription(); Image image = profile.getAvatarImage(); String avatarImageSrc = null; int avatarImageWidthNum = 0; int avatarImageHeightNum = 0; if(null != image) { avatarImageSrc = image.getSrc(); avatarImageWidthNum = image.getWidth(); avatarImageHeightNum = image.getHeight(); } String bgColor = i % 2 == 1 ? "background-color:#FFF" : ""; %> <div style="float:left;clear:both;padding:5px 0 5px 5px;cursor:pointer;<%= bgColor %>" onclick='window.location="profile.sp?profileId=<%= profileId %>"'> <div style="float:right;clear:right;padding-left:10px;width:515px;font-size:10px;color:#7e7e7e"> <h6><%= nickname %></h6> <%= description %> </div> <img style="float:left;clear:left;" alt="Avatar Image" src="<%= null != avatarImageSrc && avatarImageSrc.trim().length() > 0 ? avatarImageSrc : "images/defaultUserImage.png" %>" <%= avatarImageWidthNum < avatarImageHeightNum ? "height='59'" : "width='92'" %> /> </div> <% } // End loop %> Now, ignoring some of the code smells there, it's obvious that if someone wants to change the look of that DIV it would be neccesary to re-place all the Java/JSP code into the new HTML given (the designers don't work in JSP files, they have their own HTML versions of the website). Which is tedious, and prone to errors.

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• Ajax and using responseXML

  - by Banderdash

  Hello, I have a XML file that looks like this: <response> <library name="My Library"> <book id="1" checked-out="1"> <authors> <author>David Flanagan</author> </authors> <title>JavaScript: The Definitive Guide</title> <isbn-10>0596101996</isbn-10> </book> <book id="2" checked-out="1"> <authors> <author>John Resig</author> </authors> <title>Pro JavaScript Techniques (Pro)</title> <isbn-10>1590597273</isbn-10> </book> <book id="3" checked-out="0"> <authors> <author>Erich Gamma</author> <author>Richard Helm</author> <author>Ralph Johnson</author> <author>John M. Vlissides</author> </authors> <title>Design Patterns: Elements of Reusable Object-Oriented Software</title> <isbn-10>0201633612</isbn-10> </book> ... </library> </response> I'm using a simple JS script to, on click show all the titles of the books: <script type="text/javascript"> function loadXMLDoc() { if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari xmlhttp=new XMLHttpRequest(); } else {// code for IE6, IE5 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { xmlDoc=xmlhttp.responseXML; var txt=""; x=xmlDoc.getElementsByTagName("title"); for (i=0;i<x.length;i++) { txt=txt + x[i].childNodes[0].nodeValue + "<br />"; } document.getElementById("checkedIn").innerHTML=txt; } } xmlhttp.open("GET","ajax-response-data.xml",true); xmlhttp.send(); } </script> This works fine, as you can see here: http://clients.pixelbleed.net/ajax-test/ What I'd like to do is have the results post, on page load (not on click) into two separate DIV's depending on checked-out variable in the XML. So <book id="#" checked-out="1"> would post to the checkedIn div, <book id="#" checked-out="0"> posts to a checkedOut div. Also want to display the title and the author--would love any ideas as best method for accomplishing this. Apologize in advanced for the newbieness of my query.

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• Survey Data Model - How to avoid EAV and excessive denormalization?

  - by AlexDPC

  Hi everyone, My database skills are mediocre at best and I have to design a data model for survey data. I have spent some thoughts on this and right now I feel that I am stuck between some kind of EAV model and a design involving hundreds of tables, each with hundreds of columns (and thousands of records). There must be a better way to do this and I hope that the wise folks on this forum can help me. I have already searched various forums, but I couldn't really find a solution. If it has already been given elsewhere, please excuse me and provide me with a link so I can read it up. Some assumptions about the data I have to deal with: Each survey consists of 1 to n questionnaires Each questionnaire consists of 100-2,000 questions (please ignore that 2,000 questions really sound like a lot to answer...) Questions can be of various types: multiple-choice, free text, a number (like age, income, percentages, ...) Each survey involves 10-200 countries (These are not the respondents. The respondents are actually people in the countries.) Depending on the type of questionnaire, each questionnaire is answered by 100-20,000 respondents per country. A country can adapt the questionnaires for a survey, i.e. add, remove or edit questions The data for one country is gathered in a separate database in that country. There is no possibility for online integration from the start. The data for all countries has to be integrated later. This means for example, if a country has deleted a question, that data must somehow be derived from what they sent in order to achieve a uniform design across all countries I will have to write the integration and cleaning software, which will need to work with every country's data In the end the data needs to be exported to flat files, one rectangular grid per country and questionnaire. I have already discussed this topic with people from various backgrounds and have not come to a good solution yet. I mainly got two kinds of opinions. The domain experts, who are used to working with flat files (spreadsheet-style) for data processing and analysis vote for a denormalized structure with loads of tables and columns as I described above (1 table per country and questionnaire). This sounds terrible to me, because I learned that wide tables are to be avoided, it will be annoying to determine which columns are actually in a table when working with it, the database will become cluttered with hundreds of tables (or I even need to set up multiple databases, each with a similar yet a bit differetn design), etc. O-O-programmers vote for a strongly "normalized" design, which would effectively lead to a central table containing all the answers from all respondents to all questions. This table would either need to contain a column of type sql_variant type or multiple answer columns with different types to store answers of different types (multiple choice, free text, ..). The former would essentially be a EAV model. I tend to follow Joe Celko here, who strongly discourages its use (he calls it OTLT or "One True Lookup Table"). The latter would imply that each row would contain null cells for the not applicable types by design. Another alternative I could think of would be to create one table per answer type, i.e., one for multiple-choice questions, one for free text questions, etc.. That's not so generic, it would lead to a lot of union joins, I think and I would have to add a table if a new answer type is invented. Sorry for boring you with all this text and thank you for your input! Cheers, Alex PS: I asked the same question here: http://www.eggheadcafe.com/community/aspnet/13/10242616/survey-data-model--how-to-avoid-eav-and-excessive-denormalization.aspx

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• How to cope with developing against a poor 3rd party API/application?

  - by wsanville

  I'm a web developer, and my organization has recently started to use a proprietary ASP.NET CMS for our web sites. I was excited to get started using the CMS, thinking it would bring a lot of value to our end users and be fun to work with, since my skills are a good match for the types of projects we're using it for. That was about a year ago. Since then, we've ran into all kinds of issues, from blatant bugs in the product, to nasty edge cases in the APIs, to extremely poor documentation for developers. On about a weekly basis, we are forced to pursue workarounds and rewrite some of the out of the box functionality, and even find some of the basic features unusable. In many cases, since this is a closed source application (and obfuscated of course), there's nothing we can do as developers to solve these issues. So my question is, how does one attempt to develop a good application in such a scenario? The application mostly works when using the the exact out of the box behavior, or using one of the company's starter sites. However, my attempts to use the underlying APIs to implement slightly different, yet reasonable behavior has proved to be extremely time consuming (not to mention just as buggy), given the lack of good information about the APIs. I've given this a lot of thought, and my conflicting viewpoints are the following: Strongly advise against any customization to the CMS, as development time will rise exponentially, or even have an extremely high chance of failing. While this is accurate, I do not want to give the impression that I am not willing to code my own solutions to problems and take the initiative to implement something difficult or complex. I don't want to be perceived as someone who is not motivated, lazy, or not knowledgeable to do anything complex, because this is simply not the case. I love coding my own solutions, trying new/difficult things, I just dislike the vendor app we're using. Continue on the path I'm on now, which is hacking my way past all issues I encounter and try my best to deliver an application that meets the needs and specs exactly. My goals are to make it as seamless and easy to use as possible to the end user, even when integrating the CMS with our other applications internally. The problem I'm finding with this approach is it is very time consuming. I open support cases with the vendor on a regular basis to solve issues and to gain knowledge of their APIs, but this is extremely time consuming, and in some cases it leads to dead ends. I post on the vendors forums on a regular basis but have become frustrated as most of my posts get 0 replies. So, what would you, a reasonable developer, do in this case? How can I make the best of the situation? And just for fun, here are some of the code smells and anti-patterns I've dealt with using the product (aside from their own code blatantly failing): Use of StringBuilder to concatenate a giant string that is hard coded and does not change. They use it to concatenate their Javascript and write it out into the body tags of their pages. Methods that accept object or Microsoft.VisualBasic.Collection as the parameters. In the case of the VB Collection, the data is not a list of any kind, it's used instead of making a class. Methods that return a Hashtable of VB Collections Method names of the form MethodName_v45, MethodName_v20, etc... Multiple classes with the same name in different namespaces with different functionality/behavior. Intellisense that reads "Note: this parameter is non functional" Complete lack of coding standards, API is filled with magic numbers and magic strings. Properties with a getter of type object that accepts totally different things, like enum or strings, and throw exceptions at runtime when you pass in something not supported. And much, much, more...

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• Defend PHP; convince me it isn't horrible

  - by Jason L

  I made a tongue-in-cheek comment in another question thread calling PHP a terrible language and it got down-voted like crazy. Apparently there are lots of people here who love PHP. So I'm genuinely curious. What am I missing? What makes PHP a good language? Here are my reasons for disliking it: PHP has inconsistent naming of built-in and library functions. Predictable naming patterns are important in any design. PHP has inconsistent parameter ordering of built-in functions, eg array_map vs. array_filter which is annoying in the simple cases and raises all sorts of unexpected behaviour or worse. The PHP developers constantly deprecate built-in functions and lower-level functionality. A good example is when they deprecated pass-by-reference for functions. This created a nightmare for anyone doing, say, function callbacks. A lack of consideration in redesign. The above deprecation eliminated the ability to, in many cases, provide default keyword values for functions. They fixed this in PHP 5, but they deprecated the pass-by-reference in PHP 4! Poor execution of name spaces (formerly no name spaces at all). Now that name spaces exist, what do we use as the dereference character? Backslash! The character used universally for escaping, even in PHP! Overly-broad implicit type conversion leads to bugs. I have no problem with implicit conversions of, say, float to integer or back again. But PHP (last I checked) will happily attempt to magically convert an array to an integer. Poor recursion performance. Recursion is a fundamentally important tool for writing in any language; it can make complex algorithms far simpler. Poor support is inexcusable. Functions are case insensitive. I have no idea what they were thinking on this one. A programming language is a way to specify behavior to both a computer and a reader of the code without ambiguity. Case insensitivity introduces much ambiguity. PHP encourages (practically requires) a coupling of processing with presentation. Yes, you can write PHP that doesn't do so, but it's actually easier to write code in the incorrect (from a sound design perspective) manner. PHP performance is abysmal without caching. Does anyone sell a commercial caching product for PHP? Oh, look, the designers of PHP do. Worst of all, PHP convinces people that designing web applications is easy. And it does indeed make much of the effort involved much easier. But the fact is, designing a web application that is both secure and efficient is a very difficult task. By convincing so many to take up programming, PHP has taught an entire subgroup of programmers bad habits and bad design. It's given them access to capabilities that they lack the understanding to use safely. This has led to PHP's reputation as being insecure. (However, I will readily admit that PHP is no more or less secure than any other web programming language.) What is it that I'm missing about PHP? I'm seeing an organically-grown, poorly-managed mess of a language that's spawning poor programmers. So convince me otherwise!

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• Application shows low memory warning and crashes while loading images?

  - by Bhoomi

  I am using following code for loading images from server using following code.When i scroll UITableView application crashes. AsynchrohousImageView class .m file - (void)dealloc { [connection cancel]; //in case the URL is still downloading [connection release]; [data release]; [_imageView release]; [_activityIndicator release]; [super dealloc]; } - (void)loadImageFromURL:(NSURL*)url defaultImageName:(NSString *)defaultImageName showDefaultImage:(BOOL)defaultImageIsShown showActivityIndicator:(BOOL)activityIndicatorIsShown activityIndicatorRect:(CGRect)activityIndicatorRect activityIndicatorStyle:(UIActivityIndicatorViewStyle)activityIndicatorStyle { if (connection!=nil) { [connection release]; } if (data!=nil) { [data release]; } if ([[self subviews] count]>0) { [[[self subviews] objectAtIndex:0] removeFromSuperview]; // } if (defaultImageIsShown) { self.imageView = [[[UIImageView alloc] initWithImage:[UIImage imageNamed:defaultImageName]] autorelease]; } else { self.imageView = [[[UIImageView alloc] init] autorelease]; } [self addSubview:_imageView]; _imageView.frame = self.bounds; [_imageView setNeedsLayout]; [self setNeedsLayout]; if (activityIndicatorIsShown) { self.activityIndicator = [[[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:activityIndicatorStyle] autorelease]; [self addSubview:_activityIndicator]; _activityIndicator.frame = activityIndicatorRect; _activityIndicator.center = CGPointMake(_imageView.frame.size.width/2, _imageView.frame.size.height/2); [_activityIndicator setHidesWhenStopped:YES]; [_activityIndicator startAnimating]; } NSURLRequest* request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0]; connection = [[NSURLConnection alloc] initWithRequest:request delegate:self]; } - (void)connection:(NSURLConnection *)theConnection didReceiveData:(NSData *)incrementalData { if (data==nil) { data = [[NSMutableData alloc] initWithCapacity:2048]; } [data appendData:incrementalData]; } - (void)connectionDidFinishLoading:(NSURLConnection*)theConnection { [connection release]; connection=nil; _imageView.image = [UIImage imageWithData:data]; if (_activityIndicator) { [_activityIndicator stopAnimating]; } [data release]; data=nil; } - (UIImage*) image { UIImageView* iv = [[self subviews] objectAtIndex:0]; return [iv image]; } In ViewController Class Which loads image - (UITableViewCell *)tableView:(UITableView *)tV cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *reuseIdentifier =@"CellIdentifier"; ListCell *cell = (ListCell *)[tableView dequeueReusableCellWithIdentifier:reuseIdentifier]; if (cell==nil) { cell = [[ListCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:reuseIdentifier]; NSMutableDictionary *dicResult = [arrResults objectAtIndex:indexPath.row]; NSURL *url=[NSURL URLWithString:[dicResult objectForKey:@"Image"]]; AsynchronousImageView *asyncImageView = [[AsynchronousImageView alloc] initWithFrame:CGRectMake(5, 10,80,80)]; [asyncImageView loadImageFromURL:url defaultImageName:@"DefaultImage.png" showDefaultImage:NO showActivityIndicator:YES activityIndicatorRect:CGRectMake(5, 10,30,30) activityIndicatorStyle:UIActivityIndicatorViewStyleGray]; // load our image with URL asynchronously [cell.contentView addSubview:asyncImageView]; // cell.imgLocationView.image = [UIImage imageNamed:[dicResult valueForKey:@"Image"]]; [asyncImageView release]; } if([arrResults count]==1) { UITableViewCell *cell1=[tableView dequeueReusableCellWithIdentifier:reuseIdentifier]; if(cell1==nil) cell1=[[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:reuseIdentifier] autorelease]; NSMutableDictionary *dicResult = [arrResults objectAtIndex:0]; cell1.textLabel.text=[dicResult valueForKey:@"NoResults"]; return cell1; } else { NSMutableDictionary *dicResult = [arrResults objectAtIndex:indexPath.row]; NSString *title = [NSString stringWithFormat:@"%@ Bedrooms-%@", [dicResult valueForKey:KEY_NUMBER_OF_BEDROOMS],[dicResult valueForKey:KEY_PROPERTY_TYPE]]; NSString *strAddress = [dicResult valueForKey:KEY_DISPLAY_NAME]; NSString *address = [strAddress stringByReplacingOccurrencesOfString:@", " withString:@"\n"]; NSString *price = [dicResult valueForKey:KEY_PRICE]; NSString *distance = [dicResult valueForKey:KEY_DISTANCE]; cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator; cell.lblTitle.text = title; cell.lblAddress.text = address; if ([price length]>0) { cell.lblPrice.text = [NSString stringWithFormat:@"£%@",price]; }else{ cell.lblPrice.text = @""; } if ([distance length]>0) { cell.lblmiles.text = [NSString stringWithFormat:@"%.2f miles",[distance floatValue]]; }else{ cell.lblmiles.text = @""; } } return cell; } How can i resolve this? I have attached heapshot analysis screen shot of it.Here non Object consumes so much of memory what is that?

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• L2S DataContext out of synch: row not found or changed

  - by awrigley

  The Problem I am getting a number of errors that imply that the DataContext, or rather, the way I am using the DataContext is getting out of synch. The error occurs on db.SubmitChanges() where db is my DataContext instance. The error is: Row not found or changed. The problem only occurs intermitently, for example, adding a row then deleting it. If I stop the dev server and restart, the added row is there and I can delete it no problem. Ie, it seems that the problem is related to the DataContext losing track of the rows that have been added. IMPORTANT: Before anyone votes to close this thread, on the basis of it being a duplicate, I have checked the sql server profiler and there is no "Where 0 = 1" in the SQL. I have also recreated the dbml file, so am satisfied that the database schema is in synch with the schema represented by the dbml file. Ie, no cases of mismatched nullable/not nullable columns, etc. My Diagnosis (for what it is worth): It seems to be a problem related to how I am using the DataContext. I am new to MVC, Repositories and Services patterns, so suspect that I have wired things up wrong. The Setup Simple eLearning app in its early stages. Pupils need to be able to add and delete courses (Courses table) to their UserCourses. To do this, I have a service that gets a specific DataContext instance Dependency Injected into its constructor. Service Class Constructor: public class SqlPupilBlockService : IPupilBlockService { DataContext db; public SqlPupilBlockService(DataContext db) { this.db = db; CoursesRepository = new SqlRepository<Course>(db); UserCoursesRepository = new SqlRepository<UserCourse>(db); } // Etc, etc } The CoursesRepository and UserCoursesRepository are both private properties of the service class that are of Type IRepository (just a simple generic repository interface). Sql Respoitory Code: public class SqlRepository<T> : IRepository<T> where T : class { DataContext db; public SqlRepository(DataContext db) { this.db = db; } #region IRepository<T> Members public IQueryable<T> Query { get { return db.GetTable<T>(); } } public List<T> FetchAll() { return Query.ToList(); } public void Add(T entity) { db.GetTable<T>().InsertOnSubmit(entity); } public void Delete(T entity) { db.GetTable<T>().DeleteOnSubmit(entity); } public void Save() { db.SubmitChanges(); } #endregion } The two methods for adding and deleting UserCourses are: Service Methods for Adding and Deleting UserCourses: public void AddUserCourse(int courseId) { UserCourse uc = new UserCourse(); uc.IdCourse = courseId; uc.IdUser = UserId; uc.DateCreated = DateTime.Now; uc.DateAmended = DateTime.Now; uc.Role = "Pupil"; uc.CourseNotes = string.Empty; uc.ActiveStepIndex = 0; UserCoursesRepository.Add(uc); UserCoursesRepository.Save(); } public void DeleteUserCourse(int courseId) { var uc = (UserCoursesRepository.Query.Where(x => x.IdUser == UserId && x.IdCourse == courseId)).Single(); UserCoursesRepository.Delete(uc); UserCoursesRepository.Save(); } Ajax I am using Ajax via Ajax.BeginForm I don't think that is relevant. ASP.NET MVC 3 I am using mvc3, but don't think that is relevant: the errors are related to model code.

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• "assignment makes integer from pointer without a cast " warning in c

  - by mekasperasky

  #include<stdio.h> /* this is a lexer which recognizes constants , variables ,symbols, identifiers , functions , comments and also header files . It stores the lexemes in 3 different files . One file contains all the headers and the comments . Another file will contain all the variables , another will contain all the symbols. */ int main() { int i=0,j; char a,b[20],c[30]; FILE *fp1,*fp2; c[0]='"if"; c[1]="then"; c[2]="else"; c[3]="switch"; c[4]="printf"; c[5]="scanf"; c[6]="NULL"; c[7]="int"; c[8]="char"; c[9]="float"; c[10]="long"; c[11]="double"; c[12]="char"; c[13]="const"; c[14]="continue"; c[15]="break"; c[16]="for"; c[17]="size of"; c[18]="register"; c[19]="short"; c[20]="auto"; c[21]="while"; c[22]="do"; c[23]="case"; fp1=fopen("source.txt","r"); //the source file is opened in read only mode which will passed through the lexer fp2=fopen("lext.txt","w"); //now lets remove all the white spaces and store the rest of the words in a file if(fp1==NULL) { perror("failed to open source.txt"); //return EXIT_FAILURE; } i=0; while(!feof(fp1)) { a=fgetc(fp1); if(a!=' ') { b[i]=a; } else { for (j=0;j<23;j++) { if(c[j]==b) { fprintf(fp2, "%.20s\n", c[j]); continue ; } b[i]='\0'; fprintf(fp2, "%.20s\n", b); i=0; continue; } //else if //{ i=i+1; /*Switch(a) { case EOF :return eof; case '+':sym=sym+1; case '-':sym=sym+1; case '*':sym=sym+1; case '/':sym=sym+1; case '%':sym=sym+1; case ' */ } fclose(fp1); fclose(fp2); return 0; } This is my c code for lexical analysis .. its giving warnings and also not writing anything into the lext file ..

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• Upgrading from TFS 2010 RC to TFS 2010 RTM done

  - by Martin Hinshelwood

  Today is the big day, with the Launch of Visual Studio 2010 already done in Asia, and rolling around the world towards us, we are getting ready for the RTM (Released). We have had TFS 2010 in Production for nearly 6 months and have had only minimal problems. Update 12th April 2010  – Added Scott Hanselman’s tweet about the MSDN download release time. SSW was the first company in the world outside of Microsoft to deploy Visual Studio 2010 Team Foundation Server to production, not once, but twice. I am hoping to make it 3 in a row, but with all the hype around the new version, and with it being a production release and not just a go-live, I think there will be a lot of competition. Developers: MSDN will be updated with #vs2010 downloads and details at 10am PST *today*! @shanselman - Scott Hanselman Same as before, we need to Uninstall 2010 RC and install 2010 RTM. The installer will take care of all the complexity of actually upgrading any schema changes. If you are upgrading from TFS 2008 to TFS2010 you can follow our Rules To Better TFS 2010 Migration and read my post on our successes.   We run TFS 2010 in a Hyper-V virtual environment, so we have the advantage of running a snapshot as well as taking a DB backup. Done - Snapshot the hyper-v server Microsoft does not support taking a snapshot of a running server, for very good reason, and Brian Harry wrote a post after my last upgrade with the reason why you should never snapshot a running server. Done - Uninstall Visual Studio Team Explorer 2010 RC You will need to uninstall all of the Visual Studio 2010 RC client bits that you have on the server. Done - Uninstall TFS 2010 RC Done - Install TFS 2010 RTM Done - Configure TFS 2010 RTM Pick the Upgrade option and point it at your existing “tfs_Configuration” database to load all of the existing settings Done - Upgrade the SharePoint Extensions Upgrade Build Servers (Pending) Test the server The back out plan, and you should always have one, is to restore the snapshot. Upgrading to Team Foundation Server 2010 – Done The first thing you need to do is off the TFS server and then log into the Hyper-v server and create a snapshot. Figure: Make sure you turn the server off and delete all old snapshots before you take a new one I noticed that the snapshot that was taken before the Beta 2 to RC upgrade was still there. You should really delete old snapshots before you create a new one, but in this case the SysAdmin (who is currently tucked up in bed) asked me not to. I guess he is worried about a developer messing up his server Turn your server on and wait for it to boot in anticipation of all the nice shiny RTM’ness that is coming next. The upgrade procedure for TFS2010 is to uninstal the old version and install the new one. Figure: Remove Visual Studio 2010 Team Foundation Server RC from the system.   Figure: Most of the heavy lifting is done by the Uninstaller, but make sure you have removed any of the client bits first. Specifically Visual Studio 2010 or Team Explorer 2010.  Once the uninstall is complete, this took around 5 minutes for me, you can begin the install of the RTM. Running the 64 bit OS will allow the application to use more than 2GB RAM, which while not common may be of use in heavy load situations. Figure: It is always recommended to install the 64bit version of a server application where possible. I do not think it is likely, with SharePoint 2010 and Exchange 2010  and even Windows Server 2008 R2 being 64 bit only, I do not think there will be another release of a server app that is 32bit. You then need to choose what it is you want to install. This depends on how you are running TFS and on how many servers. In our case we run TFS and the Team Foundation Build Service (controller only) on out TFS server along with Analysis services and Reporting Services. But our SharePoint server lives elsewhere. Figure: This always confuses people, but in reality it makes sense. Don’t install what you do not need. Every extra you install has an impact of performance. If you are integrating with SharePoint you will need to run this install on every Front end server in your farm and don’t forget to upgrade your Build servers and proxy servers later. Figure: Selecting only Team Foundation Server (TFS) and Team Foundation Build Services (TFBS)   It is worth noting that if you have a lot of builds kicking off, and hence a lot of get operations against your TFS server, you can use a proxy server to cache the source control on another server in between your TFS server and your build servers. Figure: Installing Microsoft .NET Framework 4 takes the most time. Figure: Now run Windows Update, and SSW Diagnostic to make sure all your bits and bobs are up to date. Note: SSW Diagnostic will check your Power Tools, Add-on’s, Check in Policies and other bits as well. Configure Team Foundation Server 2010 – Done Now you can configure the server. If you have no key you will need to pick “Install a Trial Licence”, but it is only £500, or free with a MSDN subscription. Anyway, if you pick Trial you get 90 days to get your key. Figure: You can pick trial and add your key later using the TFS Server Admin. Here is where the real choices happen. We are doing an Upgrade from a previous version, so I will pick Upgrade the same as all you folks that are using the RC or TFS 2008. Figure: The upgrade wizard takes your existing 2010 or 2008 databases and upgraded them to the release.   Once you have entered your database server name you can click “List available databases” and it will show what it can upgrade. Figure: Select your database from the list and at this point, make sure you have a valid backup. At this point you have not made ANY changes to the databases. At this point the configuration wizard will load configuration from your existing database if you have one. If you are upgrading TFS 2008 refer to Rules To Better TFS 2010 Migration. Mostly during the wizard the default values will suffice, but depending on the configuration you want you can pick different options. Figure: Set the application tier account and Authentication method to use. We use NTLM to keep things simple as we host our TFS server externally for our remote developers.  Figure: Setting your TFS server URL’s to be the remote URL’s allows the reports to be accessed without using VPN. Very handy for those remote developers. Figure: Detected the existing Warehouse no problem. Figure: Again we love green ticks. It gives us a warm fuzzy feeling. Figure: The username for connecting to Reporting services should be a domain account (if you are on a domain that is). Figure: Setup the SharePoint integration to connect to your external SharePoint server. You can take the option to connect later.   You then need to run all of your readiness checks. These check can save your life! it will check all of the settings that you have entered as well as checking all the external services are configures and running properly. There are two reasons that TFS 2010 is so easy and painless to install where previous version were not. Microsoft changes the install to two steps, Install and configuration. The second reason is that they have pulled out all of the stops in making the install run all the checks necessary to make sure that once you start the install that it will complete. if you find any errors I recommend that you report them on http://connect.microsoft.com so everyone can benefit from your misery.   Figure: Now we have everything setup the configuration wizard can do its work.  Figure: Took a while on the “Web site” stage for some point, but zipped though after that.  Figure: last wee bit. TFS Needs to do a little tinkering with the data to complete the upgrade. Figure: All upgraded. I am not worried about the yellow triangle as SharePoint was being a little silly Exception Message: TF254021: The account name or password that you specified is not valid. (type TfsAdminException) Exception Stack Trace:    at Microsoft.TeamFoundation.Management.Controls.WizardCommon.AccountSelectionControl.TestLogon(String connectionString)    at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument) [Info   @16:10:16.307] Benign exception caught as part of verify: Exception Message: TF255329: The following site could not be accessed: http://projects.ssw.com.au/. The server that you specified did not return the expected response. Either you have not installed the Team Foundation Server Extensions for SharePoint Products on this server, or a firewall is blocking access to the specified site or the SharePoint Central Administration site. For more information, see the Microsoft Web site (http://go.microsoft.com/fwlink/?LinkId=161206). (type TeamFoundationServerException) Exception Stack Trace:    at Microsoft.TeamFoundation.Client.SharePoint.WssUtilities.VerifyTeamFoundationSharePointExtensions(ICredentials credentials, Uri url)    at Microsoft.TeamFoundation.Admin.VerifySharePointSitesUrl.Verify() Inner Exception Details: Exception Message: TF249064: The following Web service returned an response that is not valid: http://projects.ssw.com.au/_vti_bin/TeamFoundationIntegrationService.asmx. This Web service is used for the Team Foundation Server Extensions for SharePoint Products. Either the extensions are not installed, the request resulted in HTML being returned, or there is a problem with the URL. Verify that the following URL points to a valid SharePoint Web application and that the application is available: http://projects.ssw.com.au. If the URL is correct and the Web application is operating normally, verify that a firewall is not blocking access to the Web application. (type TeamFoundationServerInvalidResponseException) Exception Data Dictionary: ResponseStatusCode = InternalServerError I’ll look at SharePoint after, probably the SharePoint box just needs a restart or a kick If there is a problem with SharePoint it will come out in testing, But I will definatly be passing this on to Microsoft.   Upgrading the SharePoint connector to TFS 2010 You will need to upgrade the Extensions for SharePoint Products and Technologies on all of your SharePoint farm front end servers. To do this uninstall  the TFS 2010 RC from it in the same way as the server, and then install just the RTM Extensions. Figure: Only install the SharePoint Extensions on your SharePoint front end servers. TFS 2010 supports both SharePoint 2007 and SharePoint 2010.   Figure: When you configure SharePoint it uploads all of the solutions and templates. Figure: Everything is uploaded Successfully. Figure: TFS even remembered the settings from the previous installation, fantastic.   Upgrading the Team Foundation Build Servers to TFS 2010 Just like on the SharePoint servers you will need to upgrade the Build Server to the RTM. Just uninstall TFS 2010 RC and then install only the Team Foundation Build Services component. Unlike on the SharePoint server you will probably have some version of Visual Studio installed. You will need to remove this as well. (Coming Soon) Connecting Visual Studio 2010 / 2008 / 2005 and Eclipse to TFS2010 If you have developers still on Visual Studio 2005 or 2008 you will need do download the respective compatibility pack: Visual Studio Team System 2005 Service Pack 1 Forward Compatibility Update for Team Foundation Server 2010 Visual Studio Team System 2008 Service Pack 1 Forward Compatibility Update for Team Foundation Server 2010 If you are using Eclipse you can download the new Team Explorer Everywhere install for connecting to TFS. Get your developers to check that you have the latest version of your applications with SSW Diagnostic which will check for Service Packs and hot fixes to Visual Studio as well.   Technorati Tags: TFS,TFS2010,TFS 2010,Upgrade

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