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• Strategies for serializing an object for auditing/logging purpose in .NET?

  - by Jiho Han

  Let's say I have an application that processes messages. Messages are just objects in this case that implements IMessage interface which is just a marker. In this app, if a message fails to process, then I want to log it, first of all for auditing and troubleshooting purposes. Secondly I might want to use it for re-processing. Ideally, I want the message to be serialized into a format that is human-readable. The first candidate is XML although there are others like JSON. If I were to serialize the messages as XML, I want to know whether the message object is XML-serializable. One way is to reflect on the type and to see if it has a parameter-less constructor and the other is to require IXmlSerializable interface. I'm not too happy with either of these approaches. There is a third option which is to try to serialize it and catch exceptions. This doesn't really help - I want to, in some way, stipulate that IMessage (or a derived type) should be xml-serializable. The reflection route has obvious disadvantages such as security, performance, etc. IXmlSerializable route locks down my messages to one format, when in the future, I might want to change the serialization format to be JSON. The other thing is even the simplest objects now must implement ReadXml and WriteXml methods. Is there a route that involves the least amount of work that lets me serialize an arbitrary object (as long as it implements the marker interface) into XML but not lock future messages into XML?

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• Binding a WPF ComboBox to a different ItemsSource within a ListBox DataTemplate

  - by tjans

  I have a ListBox that contains a textbox and a combobox in its datatemplate: <ListBox Height="147" Margin="158,29,170,0" Name="PitcherListBox" VerticalAlignment="Top" ItemsSource="{Binding SomeCollectionOfObjects}" Background="Black"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal"> <TextBox Text="{Binding Path=Name}" /> <ComboBox ItemsSource="{Binding LocalArrayOfIntsProperty}" /> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> I want to bind the listbox to a collection of objects (which I've done successfully), but I want the combobox in the above datatemplate to have its itemssource set to a local property on the window (array of ints). I still want the combobox to have a two-way bind between its selected item and a property on the collection of objects... I have the following in code: PitcherListBox.DataContext = this; Basically in the end, I want the combobox within the listbox to have a different itemssource than the listbox itself. I can't seem to figure out how to change the ComboBox's ItemsSource in XAML. Can someone provide me some feedback? Thanks!

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• Django Cannot set values on a ManyToManyField which specifies an intermediary model

  - by dana

  i am using a m2m and a through table, and when i was trying to save, my error was: Cannot set values on a ManyToManyField which specifies an intermediary model so, i've modified my code, so that when i save the form, to insert data into the 'through' table too.But now, i'm having another error. (i've bolded the lines where i think i am wrong) i have in models.py: class Classroom(models.Model): user = models.ForeignKey(User, related_name = 'classroom_creator') classname = models.CharField(max_length=140, unique = True) date = models.DateTimeField(auto_now=True) open_class = models.BooleanField(default=True) members = models.ManyToManyField(User,related_name="list of invited members", through = 'Membership') class Membership(models.Model): accept = models.BooleanField(User) date = models.DateTimeField(auto_now = True) classroom = models.ForeignKey(Classroom, related_name = 'classroom_membership') member = models.ForeignKey(User, related_name = 'user_membership') and in def save_classroom(request): if request.method == 'POST': form = ClassroomForm(request.POST, request.FILES, user = request.user) **classroom_instance = Classroom member_instance = Membership** if form.is_valid(): new_obj = form.save(commit=False) new_obj.user = request.user r = Relations.objects.filter(initiated_by = request.user) membership = Membership.objects.create(**classroom = classroom_instance, member = member_instance,date=datetime.datetime.now())** new_obj.save() form.save_m2m() return HttpResponseRedirect('/classroom/classroom_view/{{user}}/') else: form = ClassroomForm(user = request.user) return render_to_response('classroom/classroom_form.html', { 'form': form, }, context_instance=RequestContext(request)) but i don't seem to initialise okay the classroom_instance and menber_instance.My error os: Cannot assign "": "Membership.classroom" must be a "Classroom" instance. Thanks!

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• Django's post_save signal behaves weirdly with models using multi-table inheritance

  - by hekevintran

  Django's post_save signal behaves weirdly with models using multi-table inheritance I am noticing an odd behavior in the way Django's post_save signal works when using a model that has multi-table inheritance. I have these two models: class Animal(models.Model): category = models.CharField(max_length=20) class Dog(Animal): color = models.CharField(max_length=10) I have a post save callback called echo_category: def echo_category(sender, **kwargs): print "category: '%s'" % kwargs['instance'].category post_save.connect(echo_category, sender=Dog) I have this fixture: [ { "pk": 1, "model": "animal.animal", "fields": { "category": "omnivore" } }, { "pk": 1, "model": "animal.dog", "fields": { "color": "brown" } } ] In every part of the program except for in the post_save callback the following is true: from animal.models import Dog Dog.objects.get(pk=1).category == u'omnivore' # True When I run syncdb and the fixture is installed, the echo_category function is run. The output from syncdb is: $ python manage.py syncdb --noinput Installing json fixture 'initial_data' from '~/my_proj/animal/fixtures'. category: '' Installed 2 object(s) from 1 fixture(s) The weird thing here is that the dog object's category attribute is an empty string. Why is it not 'omnivore' like it is everywhere else? As a temporary (hopefully) workaround I reload the object from the database in the post_save callback: def echo_category(sender, **kwargs): instance = kwargs['instance'] instance = sender.objects.get(pk=instance.pk) print "category: '%s'" % instance.category post_save.connect(echo_category, sender=Dog) This works but it is not something I like because I must remember to do it when the model inherits from another model and it must hit the database again. The other weird thing is that I must do instance.pk to get the primary key. The normal 'id' attribute does not work (I cannot use instance.id). I do not know why this is. Maybe this is related to the reason why the category attribute is not doing the right thing?

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• How do I implement repository pattern and unit of work when dealing with multiple data stores?

  - by Jason

  I have a unique situation where I am building a DDD based system that needs to access both Active Directory and a SQL database as persistence. Initially this wasnt a problem because our design was setup where we had a unit of work that looked like this: public interface IUnitOfWork { void BeginTransaction() void Commit() } and our repositories looked like this: public interface IRepository<T> { T GetByID() void Save(T entity) void Delete(T entity) } In this setup our load and save would handle the mapping between both data stores because we wrote it ourselves. The unit of work would handle transactions and would contain the Linq To SQL data context that the repositories would use for persistence. The active directory part was handled by a domain service implemented in infrastructure and consumed by the repositories in each Save() method. Save() was responsible with interacting with the data context to do all the database operations. Now we are trying to adapt it to entity framework and take advantage of POCO. Ideally we would not need the Save() method because the domain objects are being tracked by the object context and we would just need to add a Save() method on the unit of work to have the object context save the changes, and a way to register new objects with the context. The new proposed design looks more like this: public interface IUnitOfWork { void BeginTransaction() void Save() void Commit() } public interface IRepository<T> { T GetByID() void Add(T entity) void Delete(T entity) } This solves the data access problem with entity framework, but does not solve the problem with our active directory integration. Before, it was in the Save() method on the repository, but now it has no home. The unit of work knows nothing other than the entity framework data context. Where should this logic go? I argue this design only works if you only have one data store using entity framework. Any ideas how to best approach this issue? Where should I put this logic?

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• Android: Change the source of ImageView present in ListView

  - by Vivek

  Hi All, I have a ListView specified by list_item.xml Now I need to change the Image in my list inside onListItemClick. How to achieve this? //list_item.xml <?xml version="1.0" encoding="UTF-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content"> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/play" android:id="@+id/img" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="center_vertical" android:id="@+id/txt" /> </LinearLayout> I have a Custom Adapter to populate my list. Code below is the adapter. public class MyCustomAdapter extends ArrayAdapter<String> { public MyCustomAdapter(Context context, int textViewResourceId, String[] objects) { super(context, textViewResourceId, objects); // TODO Auto-generated constructor stub } @Override public View getView(int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub LayoutInflater inflater=getLayoutInflater(); View row=inflater.inflate(R.layout.list_item, parent, false); TextView label=(TextView)row.findViewById(R.id.txt); label.setText(Sounds[position]); ImageView icon=(ImageView)row.findViewById(R.id.img); icon.setMaxHeight(32); icon.setMaxWidth(32); icon.setPadding(2, 1, 5, 1); icon.setImageResource(R.drawable.play); return row; } } And in onCreate I do the following @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); try { setListAdapter(new MyCustomAdapter(this, R.layout.list_item, Sounds)); //Sounds --> String array } catch(Exception e) { e.printStackTrace(); } } Now when any row is selected, I need to change the image associated with the selected view. Your help is appreciated. Thanks.

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• Programmatically Creating fieldset, ol/ul and li tags in ASP.Net, C#

  - by Matt

  Hi, I need to write an ASP.Net form which will produce the following HTML: <fieldset> <legend>Contact Details</legend> <ol> <li> <label for="name">Name:</label> <input id="name" name="name" class="text" type="text" /> </li> <li> <label for="email">Email address:</label> <input id="email" name="email" class="text" type="text" /> </li> <li> <label for="phone">Telephone:</label> <input id="phone" name="phone" class="text" type="text" /> </li> </ol> </fieldset> However, the fields which are to be added to the form will be determined at runtime, so I need to create the fieldset at runtime and add an ordered list and listitems to it, with labels, textboxes, checkboxes etc as appropriate. I can’t find standard ASP.Net objects which will create these tags. For instance, I’d like to do something like the following in C#: FieldSet myFieldSet = new FieldSet(); myFieldSet.Legend = “Contact Details”; OrderedList myOrderedList = new OrderedList(); ListItem listItem1 = new ListItem(); ListItem listItem2 = new ListItem(); ListItem listItem3 = new ListItem(); // code here which would add labels and textboxes to the ListItems myOrderedList.Controls.Add(listItem1); myOrderedList.Controls.Add(listItem2); myOrderedList.Controls.Add(listItem3); myFieldSet.Controls.Add(myOrderedList); Form1.Controls.Add(myFieldSet); Are there any standard ASP.Net objects which can produce this, or is there some other way of achieving the same result? Matt

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• Does WPF break an Entity Framework ObjectContext?

  - by David Veeneman

  I am getting started with Entity Framework 4, and I am getting ready to write a WPF demo app to learn EF4 better. My LINQ queries return IQueryable<T>, and I know I can drop those into an ObservableCollection<T> with the following code: IQueryable<Foo> fooList = from f in Foo orderby f.Title select f; var observableFooList = new ObservableCollection<Foo>(fooList); At that point, I can set the appropriate property on my view model to the observable collection, and I will get WPF data binding between the view and the view model property. Here is my question: Do I break the ObjectContext when I move my foo list to the observable collection? Or put another way, assuming I am otherwise handling my ObjectContext properly, will EF4 properly update the model (and the database)? The reason why I ask is this: NHibernate tracks objects at the collection level. If I move an NHibernate IList<T> to an observable collection, it breaks NHibernate's change tracking mechanism. That means I have to do some very complicated object wrapping to get NHibernate to work with WPF. I am looking at EF4 as a way to dispense with all that. So, to get EF4 working with WPF, is it as simple as dropping my IQueryable<T> results into an ObservableCollection<T>. Does that preserve change-tracking on my EDM entity objects? Thanks for your help.

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• Proper way to validate model in ASP.NET MVC 2 and ViewModel apporach

  - by adrin

  I am writing an ASP.NET MVC 2 application using NHibernate and repository pattern. I have an assembly that contains my model (business entities), moreover in my web project I want to use flattened objects (possibly with additional properties/logic) as ViewModels. These VMs contain UI-specific metadata (eg. DisplayAttribute used by Html.LabelFor() method). The problem is that I don't know how to implement validation so that I don't repeat myself throughout various tiers (specifically validation rules are written once in Model and propagated to ViewModel). I am using DataAnnotations on my ViewModel but this means no validation rules are imposed on the Model itself. One approach I am considering is deriving ViewModel objects from business entities adding new properties/overriding old ones, thus preserving validation metadata between the two however this is an ugly workaround. I have seen Automapper project which helps to map properties, but I am not sure if it can handle ASP.NET MVC 2 validation metadata properly. Is it difficult to use custom validation framework in asp.net mvc 2? Do you have any patterns that help to preserve DRY in regard to validation?

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• Types issue in F#

  - by Andry

  Hello! In my ongoing adventure deep diving into f# I am understanding a lot of this powerful language but there are things that I still do not understand so clearly. One of the most important issues I need to master is types. Well the book I am reading is very straight forward and introduces entities and main functionalities with a direct approach. The first thing I could get start with is types. It introduces the main types as list, option, tuples, and so on... It is clearly underlined that all these types are IMMUTABLE for many reasons regarding functional programming and data consistance in functional programing. Well, no problems until now... But now I am getting started with Concrete Types... Well... I have problems in managing with types like list, option, tuples, types created through new operator and concrete types created using type keyword (for abbreviations, concrete types...). So my question is: how can I efficently catalogue/distinguish all types of data in f#???? I can create a perfect separation among types in C#, VB.NET... FOr example in VB.NET there are value and reference types while in C# there are only references and also int, double are treated as objects (they are objects while in VB.NET a value type is not a object and there is a split in types for this reason). Well in F# I cannot create such differences among types in the language. Can you help me? I hope I was clear.

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• Getter and Setter vs. Builder strategy

  - by Extrakun

  I was reading a JavaWorld's article on Getter and Setter where the basic premise is that getters expose internal content of an object, hence tightening coupling, and go on to provide examples using builder objects. I was rather leery of abolishing getter/setter but on second reading of the article, see to quite like the idea. However, sometimes I just need one cruical element of an entity class, such as the user's id and writing one whole class just to extract that cruical element seems like overkill. It also implies that for different view, a different type of importer/exporter must be implemented (or the whole data of the class to be exported out, thus resulting in waste). Usually I tend towards filtering the result of a getter - for example, if I need to output the price of a product in different currency, I would code it as: return CurrencyOutput::convertTo($product->price(), 'USD'); This is with the understanding that the raw output of a getter is not necessary the final result to be pushed onto a screen or a database. Is getter/setter really as bad as it is protrayed to be? When should one adopt a builder strategy, or a 'get the result and filter it' approach? How do you avoid having a class needing to know about every other objects if you are not using getter/setter?

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• Yaml::load_file acting different between development and production (Rails)

  - by James

  Hi, I am completely stumped at the nature of this problem. We export data from our application into a 'cleaned' YAML file (stripping out IDs, created_at etc). Then we (will) allow users to import these files back into the application - it is the import that is completely bugging me out. In development, YAML::load_file(params[:uploaded_data].local_path) returns an array of YAML::Objects's (and it doesn't matter which of the number of different ways the file could be loaded): [#{"exception_count"="0", "title"="Start", "amount"="70.00", "colour"=nil, "repeat_type_id"="0", "repeat_interval"="1"}}, etc etc] Which is very nice, as the attributes also include the (associated model) exceptions that you see an exception_count for. However on production (rails 2.3.2, running REE 1.8.7 and 1.8.6 for testing, tested on two different production env's, and running production locally) it returns an array of the Objects within the YAML - in this case, Event: [#, repeat_type_id: 0, colour: nil, repeat_interval: 1, exception_count: 0, etc etc] Now this would be just perplexing if it also included the associated model Exception with it - however it doesn't. Can anyone at all shed some light on why the Yaml parser would behave so differently between production and development? I'm on rails 2.3.2, running REE 1.8.7; however I've also tested running Ruby 1.8.6 with exactly the same results. Thanks for any help!

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• unable to find a MessageBodyReader

  - by Cristian Boariu

  Hi guys, I have this interface: @Path("inbox") public interface InboxQueryResourceTest { @POST @Path("{membershipExternalId}/query") @Consumes(MediaType.APPLICATION_XML) @Produces("multipart/mixed") public MultipartOutput query(@PathParam("membershipExternalId") final String membershipExternalId, @QueryParam("page") @DefaultValue("0") final int page, @QueryParam("pageSize") @DefaultValue("10") final int pageSize, @QueryParam("sortProperty") final List<String> sortPropertyList, @QueryParam("sortReversed") final List<Boolean> sortReversed, @QueryParam("sortType") final List<String> sortTypeString, final InstanceQuery instanceQuery) throws IOException; } I have implemented the method to return a MultipartOutput. I am posting an xml query from Fiddler and i receive the result without any problem. BUT i have done an integration test for the same interface, i send the same objects and i put the response like: final MultipartOutput multiPartOutput = getClient().query(getUserRestAuth(), 0, 25, null, null, null, instanceQuery); But here, so from integration tests, i receive a strange error: Unable to find a MessageBodyReader of content-type multipart/mixed;boundary="74c5b6b4-e820-452d-abea-4c56ffb514bb" and type class org.jboss.resteasy.plugins.providers.multipart.MultipartOutput Anyone has any ideea why only in integration tests i receive this error? PS: Some of you will say that i do not send application/xml as ContentType but multipart, which of course is false because the objects are annotated with the required @XmlRootElement etc, otherways neither the POST from Fiddler would work.

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• How to mimic built-in .NET serialization idioms?

  - by Matt Enright

  I have a library (written in C#) for which I need to read/write representations of my objects to disk (or to any Stream) in a particular binary format (to ensure compatibility with C/Java library implementations). The format requires a fair amount of bit-packing and some DEFLATE'd bytestreams. I would like my library, however, to be as idiomatic .NET as possible, however, and so would like to provide an API as close as possible to the normal binary serialization process. I'm aware of the ability to implement the IFormatter interface, but being that I really am unable to reuse any part of the built-in serialization stack, is it worth doing this, or will it just bring unnecessary overhead. In other words: Implement IFormatter and co. OR Just provide "Serialize"/"Deserialize" methods that act on a Stream? A good point brought up below about needing the serialization semantics for any case involving Remoting. In a case where using MarshalByRef objects is feasible, I'm pretty sure that this won't be an issue, so leaving that aside are there any benefits or drawbacks to using the ISerializable/IFormatter versus a custom stack (or, is my understanding remoting incorrectly)?

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• Problem with JMX query of Coherence node MBeans visible in JConsole

  - by Quinn Taylor

  I'm using JMX to build a custom tool for monitoring remote Coherence clusters at work. I'm able to connect just fine and query MBeans directly, and I've acquired nearly all the information I need. However, I've run into a snag when trying to query MBeans for specific caches within a cluster, which is where I can find stats about total number of gets/puts, average time for each, etc. The MBeans I'm trying to access programatically are visible when I connect to the remote process using JConsole, and have names like this: Coherence:type=Cache,service=SequenceQueue,name=SEQ%GENERATOR,nodeId=1,tier=back It would make it more flexible if I can dynamically grab all type=Cache MBeans for a particular node ID without specifying all the caches. I'm trying to query them like this: QueryExp specifiedNodeId = Query.eq(Query.attr("nodeId"), Query.value(nodeId)); QueryExp typeIsCache = Query.eq(Query.attr("type"), Query.value("Cache")); QueryExp cacheNodes = Query.and(specifiedNodeId, typeIsCache); ObjectName coherence = new ObjectName("Coherence:*"); Set<ObjectName> cacheMBeans = mBeanServer.queryMBeans(coherence, cacheNodes); However, regardless of whether I use queryMBeans() or queryNames(), the query returns a Set containing... ...0 objects if I pass the arguments shown above ...0 objects if I pass null for the first argument ...all MBeans in the Coherence:* domain (112) if I pass null for the second argument ...every single MBean (128) if I pass null for both arguments The first two results are the unexpected ones, and suggest a problem in the QueryExp I'm passing, but I can't figure out what the problem is. I even tried just passing typeIsCache or specifiedNodeId for the second parameter (with either coherence or null as the first parameter) and I always get 0 results. I'm pretty green with JMX — any insight on what the problem is? (FYI, the monitoring tool will be run on Java 5, so things like JMX 2.0 won't help me at this point.)

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• Sorting an XML in Java

  - by Java Guy

  Hello I have an XML similiar to below, which needed to be sorted using the date field. <root> <Node1><date></date></Node1> <Node1><date></date></Node1> <Node1> <date></date></Node1> <Node1> <date></date></Node1> <Node2> <date></date></Node2> <Node2> <date></date></Node2> <Node2> <date></date></Node2> <Node2> <date></date> </Node2> </root> I would like to sort the XML based on the date(say asc order), irrespective of whether the date is under Node1 or Node2. Actually in Java code I have two seperate lists, one with Node1 objects and other with Node2 obects. I can sort the list in any order sperately inside java. But I need to have the dates sorted irrespective of the nodes it is apperaing on the XML. What is the best approach to sort this way in Java? Actaully I am using Castor for marshalling the java objects to XML. If you know this can be done with Castor, that will be great!

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• DataTable vs. Collection in .Net

  - by B Pete

  I am writing a program that needs to read a set of records that describe the register map of a device I need to communicate with. Each record will have a handfull of fields that describe the properties of each register. I don't really need to edit or modify the data in my VB or C# program, though I would like to be able to display the data on a grid. I would like to store the data in a CSV file, or perhaps an XML file. I need to enable users to edit the data off-line, preferably in excel. I am considering using a DataTable or a Collection of "Register" objects (which I would define). I prototyped a DataTable, and found I can read/write XML easily using the built in methods and I can easily bind to a DataGridView. I was not able to find a way to retreive info on a single register without using a query that returns a collection of rows, even though I defined a unique primaty key column. The syntax to get a value from a column is also complex, though I could be missing something on both counts. I'm tempted to use a collection of "Register" objects that I can access via a unique key. It would be a little more coding up front, but seems like a cleaner solution overall. I should still be able to use LINQ to dataset to query subsets of registers when I need them, but would also be able to grab a single field using a the key value, something like this: Registers(keyValue).fieldName). Which would be a cleaner approach to the problem? Is there a way to read/write XML into a Collection without needing custom code? Could this be accomplished using String for a key?

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• Android Hashtable Serialization

  - by Nsyed

  Hi All, I am having a weird issue with serialization of a Hashtable. I have made a Server, Client app. Where server(PC/MAC) is serializing a Hashtable and sending it to Client(Android) through UDP. The data is sent/read correctly but I get a bunch of these messages below on LogCat. 04-12 11:19:43.059: DEBUG/dalvikvm(407): GetFieldID: unable to find field Ljava/util/Hashtable;.loadFactor:F Occasionally, I would see these 04-12 11:21:19.150: DEBUG/dalvikvm(407): GC freed 10814 objects / 447184 bytes in 97ms The app would run for 2-3 mins and then crash. Interestingly enough I do not see the Loadfactor errors on SDK 1.5. But I do see the GC Free xxxx objects, quiet often. After debugging I have found that the issue is with de-serialization and the error/warning are coming from following code Code: ByteArrayInputStream bis = new ByteArrayInputStream(bytes); ObjectInputStream ois = new ObjectInputStream(bis); object = ois.readObject(); at Code: object = ois.readObject(); on the client. My server is serializing code is the following. Code: ByteArrayOutputStream bos = new ByteArrayOutputStream(); ObjectOutputStream oos = new ObjectOutputStream(bos); oos.writeObject(obj); Any idea what is going on? Thanks for the Help!

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• How to maintain an ordered table with Core Data (or SQL) with insertions/deletions?

  - by Jean-Denis Muys

  This question is in the context of Core Data, but if I am not mistaken, it applies equally well to a more general SQL case. I want to maintain an ordered table using Core Data, with the possibility for the user to: reorder rows insert new lines anywhere delete any existing line What's the best data model to do that? I can see two ways: 1) Model it as an array: I add an int position property to my entity 2) Model it as a linked list: I add two one-to-one relations, next and previous from my entity to itself 1) makes it easy to sort, but painful to insert or delete as you then have to update the position of all objects that come after 2) makes it easy to insert or delete, but very difficult to sort. In fact, I don't think I know how to express a Sort Descriptor (SQL ORDER BY clause) for that case. Now I can imagine a variation on 1): 3) add an int ordering property to the entity, but instead of having it count one-by-one, have it count 100 by 100 (for example). Then inserting is as simple as finding any number between the ordering of the previous and next existing objects. The expensive renumbering only has to occur when the 100 holes have been filled. Making that property a float rather than an int makes it even better: it's almost always possible to find a new float midway between two floats. Am I on the right track with solution 3), or is there something smarter?

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• Good patterns for loose coupling in Java?

  - by Eye of Hell

  Hello. I'm new to java, and while reading documentation so far i can't find any good ways for programming with loose coupling between objects. For majority of languages i know (C++, C#, python, javascript) i can manage objects as having 'signals' (notification about something happens/something needed) and 'slots' (method that can be connected to signal and process notification/do some work). In all mentioned languages i can write something like this: Object1 = new Object1Class(); Object2 = new Object2Class(); Connect( Object1.ItemAdded, Object2.OnItemAdded ); Now if object1 calls/emits ItemAdded, the OnItemAdded method of Object2 will be called. Such loose coupling technique is often referred as 'delegates', 'signal-slot' or 'inversion of control'. Compared to interface pattern, technique mentioned don't need to group signals into some interfaces. Any object's methods can be connected to any delegate as long as signatures match ( C++Qt even extends this by allowing only partial signature match ). So i don't need to write additional interface code for each methods / groups of methods, provide default implementation for interface methods not used etc. And i can't see anything like this in Java :(. Maybe i'm looking a wrong way?

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• SqlLite/Fluent NHibernate integration test harness initialization not repeatable after large data se

  - by Mark Rogers

  In one of my main data integration test harnesses I create and use Fluent NHibernate's SingleConnectionSessionSourceForSQLiteInMemoryTesting, to get a fresh session for each test. After each test, I close the connection, session, and session factory, and throw out the nested StructureMap container they came from. This works for almost any simple data integration test I can think, including ones that utilize Fluent NHib's PersistenceSpecification object. When I test the application's lengthy database bootstrapping process, which creates and saves thousands of domain objects, I start seeing issues. It's not that the setup and tear down fails, in fact, the test successfully bootstraps the in-memory database as the application would bootstrap the real database in the production environment. The problem occurs when the database bootstrapping occurs a second time on a new in-memory database, with a new session and session factory. The error is: NHibernate.StaleStateException : Unexpected row count: 0; expected: 1 The row count is indeed Unexpected, the row that the application under test is looking for should be in the session. You see, it's not that any data from the last integration test is sticking around, it's that for some reason the session just stops working mid-database-boostrap. And I've looked everywhere for a place I might be holding on to an old session and I can't find one. I've searched through the code for static singleton objects, but there are none anywhere near the code in question. I have a couple StructureMap InstanceScope singleton's but they are getting thrown out with each nested container that is lost after every test teardown. I've tried every possible variation on disposing and closing every object involved with each test teardown and it still fails on this lengthy database bootstrap. But non-bootstrap related database tests appear to work fine. I'm starting to run out of options and may have to surrender lengthy database integration tests in favor of WatiN-based acceptance tests. Can anyone give me any clue about how I can figure out why some of my SingleConnectionSessionSourceForSQLiteInMemoryTesting aren't repeatable? Any advice at all, about how to make an NHibernate SqlLite database integration test harness repeatable?

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• E_ACCESSDENIED on CoCreateInstance

  - by vucetica

  Here is a code snippet #include "stdafx.h" #include <tchar.h> #include <windows.h> #include <dshow.h> #include <ExDisp.h> int _tmain(int argc, _TCHAR* argv[]) { CoInitialize(NULL); HRESULT hr = S_OK; DWORD err = 0; // Try to create graph builder IGraphBuilder* pGraph = 0; hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&pGraph ); err = GetLastError(); // Here, hr is E_ACCESSDENIED // err is 5 (ERROR_ACCESS_DENIED) // Try to create capture graph builder (succeeds) ICaptureGraphBuilder2* pBuild = 0; hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void **)&pBuild ); err = GetLastError(); // Here, hr is S_OK // err is 0 (ERROR_SUCCESS) // Try to create IWebBrowser (succeeds) IWebBrowser2* pBrowser = 0; hr = CoCreateInstance (CLSID_InternetExplorer, NULL, CLSCTX_LOCAL_SERVER, IID_IWebBrowser2, (LPVOID *)&pBrowser); err = GetLastError(); // Here, hr is S_OK // err is 0 (ERROR_SUCCESS) return 0; } I'm trying to create IFilterGraph, which fails with E_ACCESSDENIED. On the other hand, creating other directshow objects works ok. The same with some other COM objects (tried with IWebBrowser2 as an example). Any idea what can be the problem? Thanks!

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• What's the purpose of "import package"?

  - by codethief

  As I just found out import package does not make the package's modules available through package.module. The same obviously holds true for from package import subpackage as well as from package import * What's the purpose of importing a package at all then if I can't access its submodules but only the objects defined in __init__.py? It makes sense to me that from package import * would bloat the namespace, which, however, doesn't apply in case of the other two ways! I also understand that loading all submodules might take a long time. But I don't know what these unwanted side-effects, "that should only happen when the sub-module is explicitly imported", are which the author of the previous link mentions. To me it looks like doing an import package[.subpackage] (or from package import subpackage) makes absolutely no sense if I don't exactly want to access objects provided in __init__.py. Are those unwanted side effects really that serious that the language actually has to protect the programmer from causing them? Actually, I thought that Python was a little bit more about "If the programmer wants to do it, let him do it." In my case, I really do want to import all submodules with the single statement from package import subpackage, because I need all of them! Telling Python in the init.py file which submodules I'm exactly talking about (all of them!) is quite cumbersome from my point of view. Please enlighten me. :)

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• Can a function return an object? Objective-C and NSMutableArray

  - by seaworthy

  I have an NSMutableArray. It's members eventually become members of an array instance in a class. I want to put the instantiantion of NSMutable into a function and to return an array object. If I can do this, I can make some of my code easier to read. Is this possible? Here is what I am trying to figure out. //Definition: > function Objects (float a, float b) { > NSMutableArray *array = [[NSMutableArray alloc] init]; > [array addObject:[NSNumber numberWithFloat:a]]; > [array addObject:[NSNumber numberWithFloat:b]]; > //[release array]; ???????? return array; > } //Declaration: Math *operator = [[Math alloc] init]; [operator findSum:Objects(20.0,30.0)]; My code compiles if I instantiate NSMutableArray right before I send the message to the receiver. I know I can have an array argument along with the method. What I have problem seeing is how to use a function and to replace the argument with a function call. Any help is appreciated. I am interested in the concept not in suggestions to replace the findSum method.

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• Adding a JLabel to JLayeredPane from event listener not dragging.

  - by Cody

  Ok, So for some reason When I add components to a JLayeredPane in its constructor: JLabel label = new JLabel(); label.setSize(100,100); label.setText("This works"); add(label); It works perfectly fine, but If a add it later in the JLayeredPane's parent EDT it doesnt let me move the objects around but they let me see the objects. Adding from EDT: JLabel label = new JLabel(); label.setToolTipText(url.getHost()); label.setIcon(icon); label.setBorder(new LineBorder(null)); label.setSize(icon.getIconWidth(), icon.getIconHeight()); dressFrame.layeredPane.add(label, JLayeredPane.DRAG_LAYER); Dragging method: Component c = findComponentAt(e.getX(), e.getY()); if (c instanceof JLayeredPane) { pieceSelected = false; return; } Point parentLocation = c.getLocation(); xAdjustment = parentLocation.x - e.getX(); yAdjustment = parentLocation.y - e.getY(); movingPiece = c; movingPiece.setLocation(e.getX() + xAdjustment, e.getY() + yAdjustment); pieceSelected = true;

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