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• iPhone OS: Strategies for high density image work

  - by Jasconius

  I have a project that is coming around the bend this summer that is going to involve, potentially, an extremely high volume of image data for display. We are talking hundreds of 640x480-ish images in a given application session (scaled to a smaller resolution when displayed), and handfuls of very large (1280x1024 or higher) images at a time. I've already done some preliminary work and I've found that the typical 640x480ish image is just a shade under 1MB in memory when placed into a UIImageView and displayed... but the very large images can be a whopping 5+ MB's in some cases. This project is actually be targeted at the iPad, which, in my Instruments tests seems to cap out at about 80-100MB's of addressable physical memory. Details aside, I need to start thinking of how to move huge volumes of image data between virtual and physical memory while preserving the fluidity and responsiveness of the application, which will be high visibility. I'm probably on the higher ends of intermediate at Objective-C... so I am looking for some solid articles and advice on the following: 1) Responsible management of UIImage and UIImageView in the name of conserving physical RAM 2) Merits of using CGImage over UIImage, particularly for the huge images, and if there will be any performance gain 3) Anything dealing with memory paging particularly as it pertains to images I will epilogue by saying that the numbers I have above maybe off by about 10 or 15%. Images may or may not end up being bundled into the actual app itself as opposed to being loaded in from an external server.

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• Django m2m form appearing fields

  - by dana

  I have a classroom application,and a follow relation. Users can follow each other and can create classrooms.When a user creates a classroom, he can invite only the people that are following him. The Classroom model is a m2m to User table. i have in models. py: class Classroom(models.Model): creator = models.ForeignKey(User) 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") and in models.py of the follow application: class Relations(models.Model): initiated_by = models.ForeignKey(User, editable=False) date_initiated = models.DateTimeField(auto_now=True, editable = False) follow = models.ForeignKey(User, editable = False, related_name = "follow") date_follow = models.DateTimeField(auto_now=True, editable = False) and in views.py of the classroom app: def save_classroom(request, username): if request.method == 'POST': u = User.objects.get(username=username) form = ClassroomForm(request.POST, request.FILES) if form.is_valid(): new_obj = form.save(commit=False) new_obj.creator = request.user r = Relations.objects.filter(initiated_by = request.user) # new_obj.members = new_obj.save() return HttpResponseRedirect('.') else: form = ClassroomForm() return render_to_response('classroom/classroom_form.html', { 'form': form, }, context_instance=RequestContext(request)) i'm using a ModelForm for the classroom form, and the default view, taking in consideration my many to many relation with User table, in the field Members, is a list of all Users in my database. But i only want in that list the users that are in a follow relationship with the logged in user - the one who creates the classroom. How can i do that? Thanks!

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• Web Hosting URL Length Limit?

  - by Isaac Waller

  Hello, I am designing a web application which is a tie in to my iPhone application. It sends massively large URLs to the web server (15000 about.) I was using NearlyFreeSpeech.net, but they only support URLS up to 2000 characters. I was wondering if anybody knows of web hosting that will support really large URLs? Thanks, Isaac Edit: My program needs to open a picture in Safari. I could do this 2 ways: send it base64 encoded in the URL and just echo the query parameters. first POST it to the server in my application, then the server would send back a unique ID after storing the photo in a database, which I would append to a URL which I would open in Safari which retrieved the photo from the database and delete it from the database. You see, I am lazy, and I know Mobile Safari can support URI's up to 80 000 characters, so I think this is a OK way to do it. If there is something really wrong with this, please tell me. Edit: I ended up doing it the proper POST way. Thanks.

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• Defining < for STL sort algorithm - operator overload, functor or standalone function?

  - by Andy

  I have a stl::list containing Widget class objects. They need to be sorted according to two members in the Widget class. For the sorting to work, I need to define a less-than comparator comparing two Widget objects. There seems to be a myriad of ways to do it. From what I can gather, one can either: a. Define a comparison operator overload in the class: bool Widget::operator< (const Widget &rhs) const b. Define a standalone function taking two Widgets: bool operator<(const Widget& lhs, const Widget& rhs); And then make the Widget class a friend of it: class Widget { // Various class definitions ... friend bool operator<(const Widget& lhs, const Widget& rhs); }; c. Define a functor and then include it as a parameter when calling the sort function: class Widget_Less : public binary_function<Widget, Widget, bool> { bool operator()(const Widget &lhs, const Widget& rhs) const; }; Does anybody know which method is better? In particular I am interested to know if I should do 1 or 2. I searched the book Effective STL by Scott Meyer but unfortunately it does not have anything to say about this. Thank you for your reply.

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• Putting a C++ Vector as a Member in a Class that Uses a Memory Pool

  - by Deep-B

  Hey, I've been writing a multi-threaded DLL for database access using ADO/ODBC for use with a legacy application. I need to keep multiple database connections for each thread, so I've put the ADO objects for each connection in an object and thinking of keeping an array of them inside a custom threadInfo object. Obviously a vector would serve better here - I need to delete/rearrange objects on the go and a vector would simplify that. Problem is, I'm allocating a heap for each thread to avoid heap contention and stuff and allocating all my memory from there. So my question is: how do I make the vector allocate from the thread-specific heap? (Or would it know internally to allocate memory from the same heap as its wrapper class - sounds unlikely, but I'm not a C++ guy) I've googled a bit and it looks like I might need to write an allocator or something - which looks like so much of work I don't want. Is there any other way? I've heard vector uses placement-new for all its stuff inside, so can overloading operator new be worked into it? My scant knowledge of the insides of C++ doesn't help, seeing as I'm mainly a C programmer (even that - relatively). It's very possible I'm missing something elementary somewhere. If nothing easier comes up - I might just go and do the array thing, but hopefully it won't come to that. I'm using MS-VC++ 6.0 (hey, it's rude to laugh! :-P ). Any/all help will be much appreciated.

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• New NSData with range of old NSData maintaining bytes.

  - by umop

  I have a fairly large NSData (or NSMutableData if necessary) object which I want to take a small chunk out of and leave the rest. Since I'm working with large amounts of NSData bytes, I don't want to make a big copy, but instead just truncate the existing bytes. Basically: NSData *source: < a few bytes I want to discard + < big chunk of bytes I want to keep NSData *destination: < big chunk of bytes I want to keep There are truncation methods in NSMutableData, but they only truncate the end of it, whereas I want to truncate the beginning. My thoughts are to do this with the methods: - getBytes:range: and - initWithBytesNoCopy:length:freeWhenDone: However, I'm trying to figure out how to manage memory with these. I'm guessing the process will be like this (I've placed ????s where I don't know what to do): void *buffer // Get range of bytes [source getBytes:buffer range:NSMakeRange(myStart, myLength)]; // Somehow (m)alloc the memory which will be freed up in the following step ????? // Release the source, now that I've allocated the bytes [source release]; // Create a new data, recycling the bytes so they don't have to be copied NSData destination = [[NSData alloc] initWithBytesNoCopy:buffer length:myLength freeWhenDone:YES]; Thanks for the help!

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• Does Ctypes Structures and POINTERS automatically free the memory when the Python object is deleted?

  - by jsbueno

  When using Python CTypes there are the Structures, that allow you to clone c-structures on the Python side, and the POINTERS objects that create a sofisticated Python Object from a memory address value and can be used to pass objects by reference back and forth C code. What I could not find on the documentation or elsewhere is what happens when a Python object containing a Structure class that was de-referenced from a returning pointer from C Code (that is - the C function alocated memory for the structure) is itself deleted. Is the memory for the original C structure freed? If not how to do it? Furthermore -- what if the Structure contains Pointers itself, to other data that was also allocated by the C function? Does the deletion of the Structure object frees the Pointers onits members? (I doubt so) Else - -how to do it? Trying to call the system "free" from Python for the Pointers in the Structure is crashing Python for me. In other words, I have this structure filled up by a c Function call: class PIX(ctypes.Structure): """Comments not generated """ _fields_ = [ ("w", ctypes.c_uint32), ("h", ctypes.c_uint32), ("d", ctypes.c_uint32), ("wpl", ctypes.c_uint32), ("refcount", ctypes.c_uint32), ("xres", ctypes.c_uint32), ("yres", ctypes.c_uint32), ("informat", ctypes.c_int32), ("text", ctypes.POINTER(ctypes.c_char)), ("colormap", ctypes.POINTER(PIXCOLORMAP)), ("data", ctypes.POINTER(ctypes.c_uint32)) ] And I want to free the memory it is using up from Python code.

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• HTTP POST prarameters order / REST urls

  - by pq

  Let's say that I'm uploading a large file via a POST HTTP request. Let's also say that I have another parameter (other than the file) that names the resource which the file is updating. The resource cannot be not part of the URL the way you can do it with REST (e.g. foo.com/bar/123). Let's say this is due to a combination of technical and political reasons. The server needs to ignore the file if the resource name is invalid or, say, the IP address and/or the logged in user are not authorized to update the resource. Looks like, if this POST came from an HTML form that contains the resource name first and file field second, for most (all?) browsers, this order is preserved in the POST request. But it would be naive to fully rely on that, no? In other words the order of HTTP parameters is insignificant and a client is free to construct the POST in any order. Isn't that true? Which means that, at least in theory, the server may end up storing the whole large file before it can deny the request. It seems to me that this is a clear case where RESTful urls have an advantage, since you don't have to look at the POST content to perform certain authorization/error checking on the request. Do you agree? What are your thoughts, experiences?

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• Adaptive user interface/environment algorithm

  - by WowtaH

  Hi all, I'm working on an information system (in C#) that (while my users use it) gathers statistical data on what pieces of information (tables & records) each user is requesting the most, and what parts of the interface he/she uses most. I'm using this statistical data to make the application adaptive to the user's needs, both in the way the interface presents itself (eg: tab/pane-ordering) as in the way of using the frequently viewed information to (eg:) show higher in search results/suggestion-lists. What i'm looking for is an algorithm/formula to determine the current 'hotness'/relevance of these objects for a specific user. A simple 'hitcounter' for each object won't be sufficient because the user might view some information quite frequently for a period of time, and then moving on to the next, making the old information less relevant. So i think my algorithm also needs some sort of sliding/historical principle to account for the changing popularity of the objects in the application over time. So, the question is: Does anybody have some sort of algorithm that accounts for that 'popularity over time' ? Preferably with some explanation on the parameters :) Thanks! PS I've looked at other posts like http://stackoverflow.com/questions/32397/popularity-algorithm but i could't quite port it to my specific case. Any help is appreciated.

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• CrystalDecisions.Web reference version changes suddenly when run the webapp

  - by Somebody

  I'm breaking my head with this issue, I have a webapp that has a report using crystal report, in the development pc it works fine, but when copy the same project to another pc, when I load the project (VS 2003) the following msg appears: One or more projects in solution need to be updated to use Crystal Reports XI Release 2. If you choose "Yes", the update will be applied permanently... I choose "Yes" and after that I can see that CrystalDecisions.Web reference has the correct version, and location according to the develpment machine, in this case: 11.5.3300.0. But when run the webapp, I can see when the version and path suddenly changes to: 11.0.3300.0. And when trying to see the report the following error appears: Parser Error Message: The base class includes the field 'CrystalReportViewer1', but its type (CrystalDecisions.Web.CrystalReportViewer) is not compatible with the type of control (CrystalDecisions.Web.CrystalReportViewer). the asp.net has the following: <%@ Register TagPrefix="cr" Namespace="CrystalDecisions.Web" Assembly="CrystalDecisions.Web, Version=11.5.3300.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" %> How is this possible? what's happening here? EDIT This is what I did: the wrong version (11.0.3300.0) was located at: C:\Program Files\Common Files\Business Objects\3.0\managed and the right version (11.5.3300.0) is located at: C:\Program Files\Business Objects\Common\3.5\managed So I just deleted the files of the wrong solution, and I made it work in my new computer, no more errors when running the webapp, the report shows fine. But when try to do the same thing in production server, a different error came out, now an exception: This report could not be loaded due to the following issue: The type initializer for 'CrystalDecisions.CristalReports.Engine.ReportDocument' threw an exception. Any idea what could be causing this error now? Here is the code: Try Dim cr As New ReportDocument cr.Load(strpath) cr.SetDatabaseLogon("usring", "pwding") Select Case rt Case 1 cr.SummaryInfo.ReportTitle = "RMA Ticket" Case 2 cr.SummaryInfo.ReportTitle = "Service Ticket" End Select 'cr.SummaryInfo.ReportTitle = tt cr.SetParameterValue("TicketNo", tn) 'cr.SummaryInfo.ReportComments = comment CrystalReportViewer1.PrintMode = CrystalDecisions.Web.PrintMode.ActiveX CrystalReportViewer1.ReportSource = cr CrystalReportViewer1.ShowFirstPage() 'cr.Close() 'cr.Dispose() Catch ex As Exception MsgBox1.alert("This report could not be loaded due to the following issue: " & ex.Message) End Try

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• Code bacteria: evolving mathematical behavior

  - by Stefano Borini

  It would not be my intention to put a link on my blog, but I don't have any other method to clarify what I really mean. The article is quite long, and it's in three parts (1,2,3), but if you are curious, it's worth the reading. A long time ago (5 years, at least) I programmed a python program which generated "mathematical bacteria". These bacteria are python objects with a simple opcode-based genetic code. You can feed them with a number and they return a number, according to the execution of their code. I generate their genetic codes at random, and apply an environmental selection to those objects producing a result similar to a predefined expected value. Then I let them duplicate, introduce mutations, and evolve them. The result is quite interesting, as their genetic code basically learns how to solve simple equations, even for values different for the training dataset. Now, this thing is just a toy. I had time to waste and I wanted to satisfy my curiosity. however, I assume that something, in terms of research, has been made... I am reinventing the wheel here, I hope. Are you aware of more serious attempts at creating in-silico bacteria like the one I programmed? Please note that this is not really "genetic algorithms". Genetic algorithms is when you use evolution/selection to improve a vector of parameters against a given scoring function. This is kind of different. I optimize the code, not the parameters, against a given scoring function.

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• Can't Compile Correct Mapping File

  - by NoOne

  Hello, Im now developping one application in C# with Remoting objects and NHibernate. So here is a image explaining how my projects are divided. Views Layer This layer will be responsible for the users interface. This layer will always use the Controls Layer to create and edit objects; Control Layer This is my persistence layer, here Ill have all the NHibernate configuration. This is my critic point, because ListSingleton Project will have only my RemoteObject. (Here I have the App.config file) Models Layer Entity layer. Here I only have the entities classes and their respective mapping. I’ve done a test solution with no remoting and only with the projects of the Control and Model Layers. It was all working ok. Now that I added the Views Layer and set the solution to start with projects Client and Server (Client calls the Control Layer and this would do a try to persist a object) I’m getting a error at : Configuration cfg = new Configuration(); cfg.AddXmlFile("mapping/User.hbm.xml"); InnerException: {"Could not compile the mapping document: mapping/User.hbm.xml"} InnerException.InnerException: {"Could not find the dialect in the configuration"} StackTrace in the InnerException.InnerException " em NHibernate.Dialect.Dialect.GetDialect(IDictionary`2 props)\r\n em NHibernate.Cfg.Configuration.AddValidatedDocument(NamedXmlDocument doc)" But I know that there is no error in the mapping file because I used in my test application.

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• Using WCF to expose underlying process

  - by Steven

  I think I must be a little dull because I'm having so much difficulty with this. I use WCF for pretty much everything in-house, it's the most appropriate technology. I have a new Silverlight 3 app that is connecting to the WCF service and that's working fine. Where the problem begins is: Because of the expense in creating the objects within this service and the high correlation of individual objects being shared between clients I want to have a console application that basically gathers/calculates/caches all the data for the service 24/7 and the service basically connects to the console app (or whatever it is) and gets the pre-processed data. eg, think of it in terms of a stock reporting app (which it is). Person A has a portfolio of x, y z Person B has a portfolio of x, q, z, r The service needs to provide updated metrics on how their portfolio is performing. So instead of every 1 second processing person A, then person B, the app independently gathers the stock price and persons position information into memory and the service just queries the in memory result. Thanks for your help, I really am feeling dumb right now.

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• getting boost::gregorian dates from a string

  - by Chris H

  I asked a related question yesterday http://stackoverflow.com/questions/2612343/basic-boost-date-time-input-format-question It worked great for posix_time ptime objects. I'm have trouble adapting it to get Gregorian date objects. try { stringstream ss; ss << dateNode->GetText(); using boost::local_time::local_time_input_facet; //using boost::gregorian; ss.imbue(locale(locale::classic(), new local_time_input_facet("%a, %d %b %Y "))); ss.exceptions(ios::failbit); ss>>dayTime; } catch (...) { cout<<"Failed to get a date..."<<endl; //cout<<e.what()<<endl; throw; } The dateNode-GetText() function returns a pointer to a string of the form Sat, 10 Apr 2010 19:30:00 The problem is I keep getting an exception. So concretely the question is, how do I go from const char * of the given format, to a boost::gregorian::date object? Thanks again.

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• Why is my html getting mal-formed?

  - by alkaloids

  I have the following table in a form that's embedded in a formtastic form (semantic_form_for). Everything I ask to be generated by ruby shows up, but the table gets badly mangled (essentially, the tags NEVER get formed. The table headers get drawn correctly There are 14 available_date objects that get passed, and they alternate between having a time value of 1 or 2, so this is just terribly boggling, but probably simple to fix... <table class="availability_table"> <tr> <th>Date</th> <th>Early</th> <th>Late</th> </tr> <% f.fields_for :available_dates do |ad| %> <% if ad.object.time == 1 #if this is an early shift, then start the new row %> <tr><td><%= ad.object.date.strftime('%a, %b %d, %Y') %></td> <td><%= ad.collection_select(:availability , LookupAvailability.all.collect, :id, :name) %></td> <% else #otherwise end the row with just a box%> <td><%= ad.collection_select(:availability , LookupAvailability.all.collect, :id, :name) %></td></tr> <% end %> <% end %> </table> So like I said, the form functions properly, and the objects all get updated and displayed correctly and all that, it's just that the HTML isn't getting echo'd out properly so my table is all mangled. Help!

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• TFS Solution build cascading to several other builds even when common components were not modified

  - by Bob Palmer

  Hey all, here is the issue I am currently trying to work through. We are using Team Foundation Server 2008, and utilizing the automated build support out of the box. We have one very large project that encompasses a number of interrelated components and web sites, each of which is set up as a Visual Studio solution file. Many of these solutions are highly interrelated since they may contain applications, or contain common libraries or shared components. We have roughly 20 or so applications, three large web sites, and about 20 components. Each solution may include projects from other solutions. For example, a solution for a console app would also include the project files for all of the components it utilizes, since we need to ensure that when someone changes a component and rebuilds it, it is reflected in all of the projects that consume that component, and we can make sure nothing was broken. We have build projects for each solution, whether that's an application, component, or web site. For this example, we will call them solutions 01, 02, and 03. These reference multiple projects (both their own core project and test projects, plus the projects relating to various components). Solution 01 has projects A, B, and C. Solution 02 has projects C, D, and E. Solution 03 has projects E, F, and G. Now, for the problem. If I modify project A, the system will end up rebuilding all three solutions. Worse, all thirty solutions reference common projects used for data access (let's call it project H). Because they all share one project in common, if I modify any solution in my stack, even if it does not touch project H, I still end up kicking off every single build script. Any thoughts on how to address this? Ideally I would only want to kick off builds where their constituant projects were directly modified - i.e in the example below, if I modified project C, I would only rebuild solutions 01 and 02. Thanks!

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• Javascript: I can get the text of a selection, now how do I get the text outside the selection?

  - by DavidR

  I have a bit of code that returns the text of a selection and I can assign that string to a variable, but now all I need are two variables, one for the text before the selection and one for the text after the selection. Here is the code for getting the selection: function findSelection(){ //returns the selection object. var userSelection; if (window.getSelection) {userSelection = window.getSelection();} // Mozilla Selection object. else if (document.selection){userSelection = document.selection.createRange();} //gets Microsoft Text Range, should be second b/c Opera has poor support for it. if (userSelection.text){return userSelection.text} //for Microsoft Objects. else {return userSelection} //For Mozilla Objects. } Then I find the anchorOffset and focusOffset to find the caret positions. I tried using these to modify a range object, like this: var range = document.createRange(); range.setStart(textdiv,0); range.setEnd(textdiv,5); Where textdiv is a variable holding the last div the user clicked on. The problem is firefox just gives me a "Security error" code: "1000" at the line range.setStart(textdiv,0);. Is there an easier way to go about doing this? I really just need the text and nothing more.

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• What ORM for .NET should I use?

  - by eKek0

  I'm relatively new to .NET and have being using Linq2Sql for a almost a year, but it lacks some of the features I'm looking for now. I'm going to start a new project in which I want to use an ORM with the following characteristics: It has to be very productive, I don't want to be dealing with the access layer to save or retrieve objects from or to the database, but it should allows me to easily tweak any object before actually commit it to the database; also it should allows me to work easily with a changing database schema It should allows me to extend the objects mapped from the database, for example to add virtual attributes to them (virtual columns to a table) It has to be (at least almost) database agnostic, it should allows me to work with different databases in a transparent way It has to have not so much configuration or must be based on conventions to make it work It should allows me to work with Linq So, do you know any ORM that I could use? Thank you for your help. EDIT I know that an option is to use NHibernate. This appears as the facto standard for enterprise level applications, but also it seems that is not very productive because its deep learning curve. In other way, I have read in some other post here in SO that it doesn't integrate well with Linq. Is all of that true?

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• PHP: Aggregate Model Classes or Uber Model Classes?

  - by sunwukung

  In many of the discussions regarding the M in MVC, (sidestepping ORM controversies for a moment), I commonly see Model classes described as object representations of table data (be that an Active Record, Table Gateway, Row Gateway or Domain Model/Mapper). Martin Fowler warns against the development of an anemic domain model, i.e. a class that is nothing more than a wrapper for CRUD functionality. I've been working on an MVC application for a couple of months now. The DBAL in the application I'm working on started out simple (on account of my understanding - oh the benefits of hindsight), and is organised so that Controllers invoke Business Logic classes, that in turn access the database via DAO/Transaction Scripts pertinent to the task at hand. There are a few "Entity" classes that aggregate these DAO objects to provide a convenient CRUD wrapper, but also embody some of the "behaviour" of that Domain concept (for example, a user - since it's easy to isolate). Taking a look at some of the code, and thinking along refactoring some of the code into a Rich Domain Model, it occurred to me that were I to try and wrap the CRUD routines and behaviour of say, a Company into a single "Model" class, that would be a sizeable class. So, my question is this: do Models represent domain objects, business logic, service layers, all of the above combined? How do you go about defining the responsibilities for these components?

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• Automated Oracle Schema Migration Tool

  - by Dave Jarvis

  What are some tools (commercial or OSS) that provide a GUI-based mechanism for creating schema upgrade scripts? To be clear, here are the tool responsibilities: Obtain connection to recent schema version (called "source"). Obtain connection to previous schema version (called "target"). Compare all schema objects between source and target. Create a script to make the target schema equivalent to the source schema ("upgrade script"). Create a rollback script to revert the source schema, used if the upgrade script fails (at any point). Create individual files for schema objects. The software must: Use ALTER TABLE instead of DROP and CREATE for renamed columns. Work with Oracle 10g or greater. Create scripts that can be batch executed (via command-line). Trivial installation process. (Bonus) Create scripts that can be executed with SQL*Plus. Here are some examples (from StackOverflow, ServerFault, and Google searches): Change Manager Oracle SQL Developer Software that does not meet the criteria, or cannot be evaluated, includes: TOAD PL/SQL Developer - Invalid SQL*Plus statements. Does not produce ALTER statements. SQL Fairy - No installer. Complex installation process. Poorly documented. DBDiff - Crippled data set evaluation, poor customer support. OrbitDB - Crippled data set evaluation. SchemaCrawler - No easily identifiable download version for Oracle databases. SQL Compare - SQL Server, not Oracle. LiquiBase - Requires changing the development process. No installer. Manually edit config files. Does not recognize its own baseUrl parameter. The only acceptable crippling of the evaluation version is by time. Crippling by restricting the number of tables and views hides possible bugs that are only visible in the software during the attempt to migrate hundreds of tables and views.

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• Hadoop Map/Reduce - simple use example to do the following...

  - by alexeypro

  I have MySQL database, where I store the following BLOB (which contains JSON object) and ID (for this JSON object). JSON object contains a lot of different information. Say, "city:Los Angeles" and "state:California". There are about 500k of such records for now, but they are growing. And each JSON object is quite big. My goal is to do searches (real-time) in MySQL database. Say, I want to search for all JSON objects which have "state" to "California" and "city" to "San Francisco". I want to utilize Hadoop for the task. My idea is that there will be "job", which takes chunks of, say, 100 records (rows) from MySQL, verifies them according to the given search criteria, returns those (ID's) which qualify. Pros/cons? I understand that one might think that I should utilize simple SQL power for that, but the thing is that JSON object structure is pretty "heavy", if I put it as SQL schemas, there will be at least 3-5 tables joins, which (I tried, really) creates quite a headache, and building all the right indexes eats RAM faster than I one can think. ;-) And even then, every SQL query has to be analyzed to be utilizing the indexes, otherwise with full scan it literally is a pain. And with such structure we have the only way "up" is just with vertical scaling. But I am not sure it's the best option for me, as I see how JSON objects will grow (the data structure), and I see that the number of them will grow too. :-) Help? Can somebody point me to simple examples of how this can be done? Does it make sense at all? Am I missing something important? Thank you.

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• faster way to change xml to array(grails to flex)

  - by Anthony Umpad

  I have a large xml passed from grails to flex. When flex receives the xml, it converts the xml into an associative array object. Given the large xml file, it takes too long to complete the loop, is there any way in flex to make conversion faster? Below is my sample code. <xml> <car> <model>Vios</model> <type>Sedan</type> <color>Blue</color> </car> <car> <model>Camry</model> <type>Luxury</type> <color>Black</color> </car> </xml> *converted to the flex associative array below.* [Vios].type = Sedan .color = Blue [Camry].type = Luxury .color = Black *Below is a code I used in flex to convert the xml to the associative array object* var tempXML=xml.children() var tempArray:Array= new Array() for(var i:int=0;i<tempXML.length();i++) { tempArray[tempXML[i].@model]= new Object(); tempArray[tempXML[i].@model].color = tempXML[i][email protected](); tempArray[tempXML[i].@model].type = tempXML[i][email protected](); }

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• Please help us non-C++ developers understand what RAII is

  - by Charlie Flowers

  Another question I thought for sure would have been asked before, but I don't see it in the "Related Questions" list. Could you C++ developers please give us a good description of what RAII is, why it is important, and whether or not it might have any relevance to other languages? I do know a little bit. I believe it stands for "Resource Acquisition is Initialization". However, that name doesn't jive with my (possibly incorrect) understanding of what RAII is: I get the impression that RAII is a way of initializing objects on the stack such that, when those variables go out of scope, the destructors will automatically be called causing the resources to be cleaned up. So why isn't that called "using the stack to trigger cleanup" (UTSTTC:)? How do you get from there to "RAII"? And how can you make something on the stack that will cause the cleanup of something that lives on the heap? Also, are there cases where you can't use RAII? Do you ever find yourself wishing for garbage collection? At least a garbage collector you could use for some objects while letting others be managed? Thanks.

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• Bi-directional view model syncing with "live" collections and properties (MVVM)

  - by Schneider

  I am getting my knickers in a twist recently about View Models (VM). Just like this guy I have come to the conclusion that the collections I need to expose on my VM typically contain a different type to the collections exposed on my business objects. Hence there must be a bi-directional mapping or transformation between these two types. (Just to complicate things, on my project this data is "Live" such that as soon as you change a property it gets transmitted to other computers) I can just about cope with that concept, using a framework like Truss, although I suspect there will be a nasty surprise somewhere within. Not only must objects be transformed but a synchronization between these two collections is required. (Just to complicate things I can think of cases where the VM collection might be a subset or union of business object collections, not simply a 1:1 synchronization). I can see how to do a one-way "live" sync, using a replicating ObservableCollection or something like CLINQ. The problem then becomes: What is the best way to create/delete items? Bi-directinal sync does not seem to be on the cards - I have found no such examples, and the only class that supports anything remotely like that is the ListCollectionView. Would bi-directional sync even be a sensible way to add back into the business object collection? All the samples I have seen never seem to tackle anything this "complex". So my question is: How do you solve this? Is there some technique to update the model collections from the VM? What is the best general approach to this?

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• Really simple JSON serialization in .NET

  - by Evgeny

  I have some simple .NET objects I'd like to serialize to JSON and back again. The set of objects to be serialized is quite small and I control the implementation, so I don't need a generic solution that will work for everything. Since my assembly will be distributed as a library I'd really like to avoid a dependency on some third-party DLL: I just want to give users one assembly that they can reference. I've read the other questions I could find on converting to and from JSON in .NET. The recommended solution of JSON.NET does work, of course, but it requires distributing an extra DLL. I don't need any of the fancy features of JSON.NET. I just need to handle a simple object (or even dictionary) that contains strings, integers, DateTimes and arrays of strings and bytes. On deserializing I'm happy to get back a dictionary - it doesn't need to create the object again. Is there some really simple code out there that I could compile into my assembly to do this simple job? I've also tried System.Web.Script.Serialization.JavaScriptSerializer, but where it falls down is the byte array: I want to base64-encode it and even registering a converter doesn't let me easily accomplish that due to the way that API works (it doesn't pass in the name of the field).

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