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  • Simply doing modelType.ToString() isn't sufficient, How can i use it via Activator.CreateInstance?

    - by programmerist
    public class MyController { public object CreateByEnum(DataModelType modeltype) { string enumText = modeltype.ToString(); // will return for example "Company" Type classType = Type.GetType(enumText); // the Type for Company class object t = Activator.CreateInstance(classType); // create an instance of Company class return t; } } public class CompanyView { public static List<Personel> GetPersonel() { MyController controller = new MyController(); _Company company = controller.CreateByEnum(DataModelType.Company) as _Company; return company.GetPersonel(); } } public enum DataModelType { xyz, klm, tucyz, Company } Yes, I agree Activator.CreateInstance() is very useful. Unfortunately, I need to pass in the correct type. That means building the correct string to pass to Type.GetType(). If I trace through the call to Controller.CreatebyEnum() in the code I posted above, simply doing modelType.ToString() isn't sufficient, even for the case of DataModelType.Company. My solution'll be maintenance bottleneck. What would be better is something that takes the results of modelType.ToString() and then recursively searches through all the types found in all the assemblies loaded in the current AppDomain. According to MSDN, Type.GetType() only searches the current calling assembly, and mscorlib.dll. How can i do that? . i need best performance?

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  • To implement a remote desktop sharing solution

    - by Cameigons
    Hi, I'm on planning/modeling phase to develop a remote desktop sharing solution, which must be web browser based. In other words: an user will be able to see and interact with someone's remote desktop using his web-browser. Everything the user who wants to share his desktop will need, besides his browser, is installing an add-in, which he's going to be prompted about when necessary. The add-in is required since (afaik) no browser technology allows desktop control from an app running within the browser alone. The add-in installation process must be as simple and transparent as possible to the user (similar to AdobeConnectNow, in case anyone's acquainted with it). The user can share his desktop with lots of people at the same time, but concede desktop control to only one of them at a time(makes no sense being otherwise). Project requirements: All technology employed must be open-source license compatible Both front ends are going to be in flash (browser) Must work on Linux, Windows XP(and later) and MacOSX. Must work at least with IE7(and later) and Firefox3.0(and later). At the very least, once the sharer's stream hits the server from where it'll be broadcast, hereon it must be broadcasted in flv (so I'm thinking whether to do the encoding at the client's machine (the one sharing the desktop) or send it in some other format to the server and encode it there). Performance and scalability are important: It must be able to handle hundreds of dozens of users(one desktop sharer, the rest viewers) We'll definitely be using red5. My doubts concern mostly implementing the desktop publisher side (add-in and streamer): 1) Are you aware of other projects that I could look into for ideas? (I'm aware of bigbluebutton.org and code.google.com/p/openmeetings) 2) Should I base myself on VNC ? 3) Bearing in mind the need to have it working cross-platform, what language should I go with? (My team is very used with java and I have some knowledge of C/C++, but anything goes really). 4) Any other advices are appreciated.

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  • Returning Database Blobs in TurboGears 2.x / FCGI / Lighttpd extremely slow

    - by Tom
    Hey everyone, I am running a TG2 App on lighttpd via flup/fastcgi. We are reading images (~30kb each) from BlobFields in a MySQL database and return those images with a custom mime type via a controller method. Caching these images on the hard disk makes no sense because they change with every request, the only reason we cache these in the DB is that creating these images is quite expensive and the data used to create the images is also present in plain text on the website. Now to the problem itself: When returning such an image, things get extremely slow. The code runs totally fine on paster itself with no visible delay, but as soon as its running via fcgi/lighttpd the described phenomenon happens. I profiled the method of my controller that returns my blob, and the entire method runs in a few miliseconds, but when "return" executes, the entire app hangs for roughly 10 seconds. We could not reproduce the same error with PHP on FCGI. This only seems to happen with Turbogears or Pylons. Here for your consideration the concerned piece of source code: @expose(content_type=CUSTOM_CONTENT_TYPE) def return_img(self, img_id): """ Return a DB persisted image when requested """ img = model.Images.by_id(img_id) #get image from DB response.headers['content-type'] = 'image/png' return img.data # this causes the app to hang for 10 seconds

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  • Call method immediately after object construction in LINQ query

    - by Steffen
    I've got some objects which implement this interface: public interface IRow { void Fill(DataRow dr); } Usually when I select something out of db, I go: public IEnumerable<IRow> SelectSomeRows { DataTable table = GetTableFromDatabase(); foreach (DataRow dr in table.Rows) { IRow row = new MySQLRow(); // Disregard the MySQLRow type, it's not important row.Fill(dr); yield return row; } } Now with .Net 4, I'd like to use AsParallel, and thus LINQ. I've done some testing on it, and it speeds up things alot (IRow.Fill uses Reflection, so it's hard on the CPU) Anyway my problem is, how do I go about creating a LINQ query, which calls Fills as part of the query, so it's properly parallelized? For testing performance I created a constructor which took the DataRow as argument, however I'd really love to avoid this if somehow possible. With the constructor in place, it's obviously simple enough: public IEnumerable<IRow> SelectSomeRowsParallel { DataTable table = GetTableFromDatabase(); return from DataRow dr in table.Rows.AsParallel() select new MySQLRow(dr); } However like I said, I'd really love to be able to just stuff my Fill method into the LINQ query, and thus not need the constructor overload.

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  • Load SQL query result data into cache in advance

    - by Marc
    I have the following situation: .net 3.5 WinForm client app accessing SQL Server 2008 Some queries returning relatively big amount of data are used quite often by a form Users are using local SQL Express and restarting their machines at least daily Other users are working remotely over slow network connections The problem is that after a restart, the first time users open this form the queries are extremely slow and take more or less 15s on a fast machine to execute. Afterwards the same queries take only 3s. Of course this comes from the fact that no data is cached and must be loaded from disk first. My question: Would it be possible to force the loading of the required data in advance into SQL Server cache? Note My first idea was to execute the queries in a background worker when the application starts, so that when the user starts the form the queries will already be cached and execute fast directly. I however don't want to load the result of the queries over to the client as some users are working remotely or have otherwise slow networks. So I thought just executing the queries from a stored procedure and putting the results into temporary tables so that nothing would be returned. Turned out that some of the result sets are using dynamic columns so I couldn't create the corresponding temp tables and thus this isn't a solution. Do you happen to have any other idea?

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  • How to receive Email in JEE application

    - by Hank
    Obviously it's not so difficult to send out emails from a JEE application via JavaMail. What I am interested in is the best pattern to receive emails (notification bounces, mostly)? I am not interested in IMAP/POP3-based approaches (polling the inbox) - my application shall react to inbound emails. One approach I could think of would be Keep existing MTA (postfix on linux in my case) - ops team already knows how to configure / operate it For every mail that arrives, spawn a Java app that receives the data and sends it off via JMS. I could do this via an entry in /etc/aliases like myuser: "|/path/to/javahelper" with javahelper calling the Java app, passing STDIN along. MDB (part of JEE application) receives JMS message, parses it, detects bounce message and acts accordingly. Another approach could be Open a listening network socket on port 25 on the JEE application container. Associate a SessionBean with the socket. Bean is part of JEE application and can parse/detect bounces/handle the messages directly. Keep existing MTA as inbound relay, do all its security/spam filtering, but forward emails to myuser (that pass the filter) to the JEE application container, port 25. The first approach I have done before (albeit in a different language/setup). From a performance and (perceived) cleanliness point of view, I think the second approach is better, but it would require me to provide a proper SMTP transport implementation. Also, I don't know if it's at all possible to connect a network socket with a bean... What is your recommendation? Do you have details about the second approach?

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  • What arguments to use to explain why SQL Server is far better then a flat file

    - by jamone
    The higher ups in my company were told by good friends that flat files are the way to go, and we should switch from SQL Server to them for everything we do. We have over 300 servers and hundreds of different databases. From just the few I'm involved with we have 10 billion records in quite a few of them with upwards of 100k new records a day and who knows how many updates... Me and a couple others need to come up with a response saying why we shouldn't do this. Most of our stuff is ASP.NET with some legacy ASP. We thought that making a simple console app that tests/times the same interactions between a flat file (stored on the network) and SQL over the network doing large inserts, searches, updates etc along with things like network disconnects randomly. This would show them how bad flat files can be especially when you are dealing with millions of records. What things should I use in my response? What should I do with my demo code to illustrate this? My sort list so far: Security Concurrent access Performance with large amounts of data Amount of time to do such a massive rewrite/switch Lack of transactions PITA to map relational data to flat files NTFS doesn't support tons of files in a directory well I fear that this will be a great post on the Daily WTF someday if I can't stop it now.

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  • How to make std::vector's operator[] compile doing bounds checking in DEBUG but not in RELEASE

    - by Edison Gustavo Muenz
    I'm using Visual Studio 2008. I'm aware that std::vector has bounds checking with the at() function and has undefined behaviour if you try to access something using the operator [] incorrectly (out of range). I'm curious if it's possible to compile my program with the bounds checking. This way the operator[] would use the at() function and throw a std::out_of_range whenever something is out of bounds. The release mode would be compiled without bounds checking for operator[], so the performance doesn't degrade. I came into thinking about this because I'm migrating an app that was written using Borland C++ to Visual Studio and in a small part of the code I have this (with i=0, j=1): v[i][j]; //v is a std::vector<std::vector<int> > The size of the vector 'v' is [0][1] (so element 0 of the vector has only one element). This is undefined behaviour, I know, but Borland is returning 0 here, VS is crashing. I like the crash better than returning 0, so if I can get more 'crashes' by the std::out_of_range exception being thrown, the migration would be completed faster (so it would expose more bugs that Borland was hiding).

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  • Handling form from different view and passing form validation through session in django

    - by Mo J. Mughrabi
    I have a requirement here to build a comment-like app in my django project, the app has a view to receive a submitted form process it and return the errors to where ever it came from. I finally managed to get it to work, but I have doubt for the way am using it might be wrong since am passing the entire validated form in the session. below is the code comment/templatetags/comment.py @register.inclusion_tag('comment/form.html', takes_context=True) def comment_form(context, model, object_id, next): """ comment_form() is responsible for rendering the comment form """ # clear sessions from variable incase it was found content_type = ContentType.objects.get_for_model(model) try: request = context['request'] if request.session.get('comment_form', False): form = CommentForm(request.session['comment_form']) form.fields['content_type'].initial = 15 form.fields['object_id'].initial = 2 form.fields['next'].initial = next else: form = CommentForm(initial={ 'content_type' : content_type.id, 'object_id' : object_id, 'next' : next }) except Exception as e: logging.error(str(e)) form = None return { 'form' : form } comment/view.py def save_comment(request): """ save_comment: """ if request.method == 'POST': # clear sessions from variable incase it was found if request.session.get('comment_form', False): del request.session['comment_form'] form = CommentForm(request.POST) if form.is_valid(): obj = form.save(commit=False) if request.user.is_authenticated(): obj.created_by = request.user obj.save() messages.info(request, _('Your comment has been posted.')) return redirect(form.data.get('next')) else: request.session['comment_form'] = request.POST return redirect(form.data.get('next')) else: raise Http404 the usage is by loading the template tag and firing {% comment_form article article.id article.get_absolute_url %} my doubt is if am doing the correct approach or not by passing the validated form to the session. Would that be a problem? security risk? performance issues? Please advise Update In response to Pol question. The reason why I went with this approach is because comment form is handled in a separate app. In my scenario, I render objects such as article and all I do is invoke the templatetag to render the form. What would be an alternative approach for my case? You also shared with me the django comment app, which am aware of but the client am working with requires a lot of complex work to be done in the comment app thats why am working on a new one.

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  • Technology and language for a stable Digital Audio Workstation development

    - by Kill KRT
    Hi, I'm designing a cross platform (Windows/Linux/OS X) application, something like a digital audio workstation. I'd like to create a software where users have a fully featured sequencer (multiple tracks with automation) and where it is possible to create instruments using a visual language (as Pure Data/Max MSP). Ehm... I know that I've already posted a question about a related issue... But in order to decide which technology I should use, I think I'd better to make more investigation. I'm a quite experted user of audio trackers (Renoise, Protracker,...) and sequencers (FL Studio, Cubase 5), but I didn't ever try to develop even a basic audio tracker. I know just the basic theory of mixing sound and know how basically a DSP works. My questions are: Where I can find a good tutorial/guide/book about this issue? Do you think using C# (with NAudio) could dramatically reduce performance? I know C++ would be the best choice, but I find C# so elegant and easy to build and port, while C++ is so powerful and fast, but there are too #define and bad things for my taste! ;-) Thank you.

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  • What effects has working in rotating shifts on programming teams?

    - by eKek0
    I work in a bank, and the boss now want's that we, the programming team, work on rotating shifts. He wants that sometimes we work from 7am to 3pm, and sometimes on 11.30am to 7.30pm. He says that we will be more productive working this way, because he has worked with teams just like that and he just knows that. Nobody of the team wants this change, but we don't know how to effectively reject this new rule. I was trying to find some empirical (or almost) evidence about how rotating shifts affects performance of programming teams, and I couldn't. I had read something about rotating shifts, but not exactly about the effect of this on programming teams. Do you know any research about rotating shifts on programming teams? Did you have any experience with this kind of work? EDIT: Other teams of the company, like the database administrators team, the help desk team, the communication team or the network administrators team are already working in rotating shifts, and they don't like this but they do it anyway. I think the boss want that we work on rotating shifts too because of them, but since only we do programming I think the effects of rotating shifts could be, at least, different for us.

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  • Should java try blocks be scoped as tightly as possible?

    - by isme
    I've been told that there is some overhead in using the Java try-catch mechanism. So, while it is necessary to put methods that throw checked exception within a try block to handle the possible exception, it is good practice performance-wise to limit the size of the try block to contain only those operations that could throw exceptions. I'm not so sure that this is a sensible conclusion. Consider the two implementations below of a function that processes a specified text file. Even if it is true that the first one incurs some unnecessary overhead, I find it much easier to follow. It is less clear where exactly the exceptions come from just from looking at statements, but the comments clearly show which statements are responsible. The second one is much longer and complicated than the first. In particular, the nice line-reading idiom of the first has to be mangled to fit the readLine call into a try block. What is the best practice for handling exceptions in a funcion where multiple exceptions could be thrown in its definition? This one contains all the processing code within the try block: void processFile(File f) { try { // construction of FileReader can throw FileNotFoundException BufferedReader in = new BufferedReader(new FileReader(f)); // call of readLine can throw IOException String line; while ((line = in.readLine()) != null) { process(line); } } catch (FileNotFoundException ex) { handle(ex); } catch (IOException ex) { handle(ex); } } This one contains only the methods that throw exceptions within try blocks: void processFile(File f) { FileReader reader; try { reader = new FileReader(f); } catch (FileNotFoundException ex) { handle(ex); return; } BufferedReader in = new BufferedReader(reader); String line; while (true) { try { line = in.readLine(); } catch (IOException ex) { handle(ex); break; } if (line == null) { break; } process(line); } }

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  • Delphi Pascal / Windows API - Small problem with SetFilePointerEx and parameter FILE_END

    - by SuicideClutchX2
    I know I am about to be slapped by at least one person who was helping me with this API. Alright I have been able to use SetFilePointerEx just fine, when setting the position only. SetFilePointerEx(PD,512,@PositionVar,FILE_BEGIN); SetFilePointerEx(PD,0,@PositionVar,FILE_CURRENT); Both work, I can set positions and even check my current one. But when I set FILE_END as per the documentation no matter what the second parameter is and whether or not i provide a pointer for the third parameter it fails even on a valid handle that many other operations are able to use without fail. For Example: SetFailed := SetFilePointerEx(PD,0,@PositionVar,FILE_END); SetFailed := SetFilePointerEx(PD,0,nil,FILE_END); Whatever I put it fails. I am working with a handle to a physical disk and it most definitely has an end. SetFilePointer works just fine its just a little more trouble than I would like. Its not the end of the world, but whats happening.

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  • IIS 6+ASP.NET - many temp files generated

    - by moshe_ravid
    I have a ASP.NET + some .NET web-services running on IIS 6 (win 2003 server). The issue is that IIS is generating a lot (!) of files in "c:\WINDOWS\Temp" directory. a lot of files means thousands of files, which get to more than 3G of size so far. The files are generated by this command: C:\WINDOWS\SysWOW64\inetsrv "C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\csc.exe" /t:library /utf8output /R:"C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\vfagt\113819dd\db0d5802\assembly\dl3\fedc6ef1\006e24d8_3bc9ca01\VfAgentWService.DLL" /R:"C:\WINDOWS\assembly\GAC_MSIL\System.Web.Services\2.0.0.0__b03f5f7f11d50a3a\System.Web.Services.dll" /R:"C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\mscorlib.dll" /R:"C:\WINDOWS\assembly\GAC_MSIL\System.Xml\2.0.0.0__b77a5c561934e089\System.Xml.dll" /R:"C:\WINDOWS\assembly\GAC_MSIL\System\2.0.0.0__b77a5c561934e089\System.dll" /out:"C:\WINDOWS\TEMP\9i_i2bmg.dll" /debug- /optimize+ /nostdlib /D:_DYNAMIC_XMLSERIALIZER_COMPILATION "C:\WINDOWS\TEMP\9i_i2bmg.0.cs" The files in the temp directory are pairs of *.out & *.err, where the *.err file is zero size, and the *.out file contains the compilation output messages. What is causing IIS to generate so many files? How can I prevent it? UPDATE: The problem is that the command i described above (csc.exe) is being executed many (many) times, causing the .out & .err to be generated so many times, until it consumes the disk space. So - my question is: what is causing this command to run so many times? (i don't have that many .aspx & .asmx files in my web app). Thanks, Moe

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  • Best XML format for log events in terms of tool support for data mining and visualization?

    - by Thorbjørn Ravn Andersen
    We want to be able to create log files from our Java application which is suited for later processing by tools to help investigate bugs and gather performance statistics. Currently we use the traditional "log stuff which may or may not be flattened into text form and appended to a log file", but this works the best for small amounts of information read by a human. After careful consideration the best bet has been to store the log events as XML snippets in text files (which is then treated like any other log file), and then download them to the machine with the appropriate tool for post processing. I'd like to use as widely supported an XML format as possible, and right now I am in the "research-then-make-decision" phase. I'd appreciate any help both in terms of XML format and tools and I'd be happy to write glue code to get what I need. What I've found so far: log4j XML format: Supported by chainsaw and Vigilog. Lilith XML format: Supported by Lilith Uninvestigated tools: Microsoft Log Parser: Apparently supports XML. OS X log viewer: plus there is a lot of tools on http://www.loganalysis.org/sections/parsing/generic-log-parsers/ Any suggestions?

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  • SQL Server full text query across multiple tables - why so slow?

    - by Mikey Cee
    Hi. I'm trying to understand the performance of an SQL Server 2008 full-text query I am constructing. The following query, using a full-text index, returns the correct results immediately: SELECT O.ID, O.Name FROM dbo.EventOccurrence O WHERE FREETEXT(O.Name, 'query') ie, all EventOccurrences with the word 'query' in their name. And the following query, using a full-text index from a different table, also returns straight away: SELECT V.ID, V.Name FROM dbo.Venue V WHERE FREETEXT(V.Name, 'query') ie. all Venues with the word 'query' in their name. But if I try to join the tables and do both full-text queries at once, it 12 seconds to return: SELECT O.ID, O.Name FROM dbo.EventOccurrence O INNER JOIN dbo.Event E ON O.EventID = E.ID INNER JOIN dbo.Venue V ON E.VenueID = V.ID WHERE FREETEXT(E.Name, 'search') OR FREETEXT(V.Name, 'search') Here is the execution plan: http://uploadpad.com/files/query.PNG From my reading, I didn't think it was even possible to make a free text query across multiple tables in this way, so I'm not sure I am understanding this correctly. Note that if I remove the WHERE clause from this last query then it returns all results within a second, so it's definitely the full-text that is causing the issue here. Can someone explain (i) why this is so slow and (ii) if this is even supported / if I am even understanding this correctly. Thanks in advance for your help.

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  • Failure remediation strategy for File I/O

    - by Brett
    I'm doing buffered IO into a file, both read and write. I'm using fopen(), fseeko(), standard ANSI C file I/O functions. In all cases, I'm writing to a standard local file on a disk. How often do these file I/O operations fail, and what should the strategy be for failures? I'm not exactly looking for stats, but I'm looking for a general purpose statement on how far I should go to handle error conditions. For instance, I think everyone recognizes that malloc() could and probably will fail someday on some user's machine and the developer should check for a NULL being returned, but there is no great remediation strategy since it probably means the system is out of memory. At least, this seems to be the approach taken with malloc() on desktop systems, embedded systems are different. Likewise, is it worth reattempting a file I/O operation, or should I just consider a failure to be basically unrecoverable, etc. I would appreciate some code samples demonstrating proper usage, or a library guide reference that indicates how this is to be handled. Any other data is, of course, welcome.

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  • File based caching under PHP

    - by azatoth
    I've been using http://code.google.com/p/phpbrowscap/ for a project, and it usually works nice. But a few times it's cache, which is plain php-files (see http://code.google.com/p/phpbrowscap/source/browse/trunk/browscap/Browscap.php#372 et. al.), has been "zeroed", i.e. the whole cache file has become large blob of NULLs. Instead of trying to find out why the files become NULL, I though perhaps it might be better to change the caching strategy to something more resilient. So I do wonder if you has any good ideas what would be a good solution; I've been looking at http://www.jongales.com/blog/2009/02/18/simple-file-based-php-cache-class/ and http://www.phpclasses.org/package/313-PHP-Cache-arbitrary-data-in-files-.html and I also though of just saving an serialized array to the file instead of pure php as it's been doing now; But I'm uncertain what approach I should target here. I'm grateful for any insight into this area of technology, as I know it's complex from a performance point of view.

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  • Architecture for database analytics

    - by David Cournapeau
    Hi, We have an architecture where we provide each customer Business Intelligence-like services for their website (internet merchant). Now, I need to analyze those data internally (for algorithmic improvement, performance tracking, etc...) and those are potentially quite heavy: we have up to millions of rows / customer / day, and I may want to know how many queries we had in the last month, weekly compared, etc... that is the order of billions entries if not more. The way it is currently done is quite standard: daily scripts which scan the databases, and generate big CSV files. I don't like this solutions for several reasons: as typical with those kinds of scripts, they fall into the write-once and never-touched-again category tracking things in "real-time" is necessary (we have separate toolset to query the last few hours ATM). this is slow and non-"agile" Although I have some experience in dealing with huge datasets for scientific usage, I am a complete beginner as far as traditional RDBM go. It seems that using column-oriented database for analytics could be a solution (the analytics don't need most of the data we have in the app database), but I would like to know what other options are available for this kind of issues.

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  • JTA or LOCAL transactions in JPA2+Hibernate 3.6.0?

    - by Pangea
    We are in the process of re-thinking our tech stack and below are our choices (We can't live without Spring and Hibernate due to the complexity etc of the app). We are also moving from J2EE 1.4 to JEE 5. Tech stack JEE 5 JPA 2.0 (I know JEE 5 only supports JPA 1.0 but we want to use Hibernate as the JPA provider) Hibernate 3.6.0 (We already have lots of hbm files with custom types etc. so we doesn't want to migrate them at this time to JPA. This means we want both jpa/hbm mappings work together and hence the Hibernate as the JPA provider instead of using the default that comes with App Server) Now the problems is that I want to stick with local transactions but other team members want to use JTA. I have been working with J2EE for last 9 years and I've heard time and again people suggesting to stick with local transactions if I doesn't need two phase commits. This is not only for performance reasons but debugging/troubleshooting a local transaction is lot easier than a distributed transaction. My suggestion is to use spring declarative transaction management + local transactions (HibernateTransactionManager) I want to make sure if I am being paranoid or I have a valid point. I'd like to hear what the rest of the JEE world thinks. Thank you.

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  • iPhone: Using dispatch_after to mimick NSTimer

    - by Joseph Tura
    Don't know a whole lot about blocks. How would you go about mimicking a repeating NSTimer with dispatch_after? My problem is that I want to "pause" a timer when the app moves to the background, but subclassing NSTimer does not seem to work. I tried something which seems to work. I cannot judge its performance implications or whether it could be greatly optimized. Any input is welcome. #import "TimerWithPause.h" @implementation TimerWithPause @synthesize timeInterval; @synthesize userInfo; @synthesize invalid; @synthesize invocation; + (TimerWithPause *)scheduledTimerWithTimeInterval:(NSTimeInterval)aTimeInterval target:(id)aTarget selector:(SEL)aSelector userInfo:(id)aUserInfo repeats:(BOOL)aTimerRepeats { TimerWithPause *timer = [[[TimerWithPause alloc] init] autorelease]; timer.timeInterval = aTimeInterval; NSMethodSignature *signature = [[aTarget class] instanceMethodSignatureForSelector:aSelector]; NSInvocation *aInvocation = [NSInvocation invocationWithMethodSignature:signature]; [aInvocation setSelector:aSelector]; [aInvocation setTarget:aTarget]; [aInvocation setArgument:&timer atIndex:2]; timer.invocation = aInvocation; timer.userInfo = aUserInfo; if (!aTimerRepeats) { timer.invalid = YES; } [timer fireAfterDelay]; return timer; } - (void)fireAfterDelay { dispatch_time_t delay = dispatch_time(DISPATCH_TIME_NOW, self.timeInterval * NSEC_PER_SEC); dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_after(delay, queue, ^{ [invocation performSelectorOnMainThread:@selector(invoke) withObject:nil waitUntilDone:NO]; if (!invalid) { [self fireAfterDelay]; } }); } - (void)invalidate { invalid = YES; [invocation release]; invocation = nil; [userInfo release]; userInfo = nil; } - (void)dealloc { [self invalidate]; [super dealloc]; } @end

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  • Events and references pattern

    - by serhio
    In a project I have the following relation between BO and GUI By e.g. G could represent a graphic with time lines, C a TimeLine curve, P - points of that curve and T the time that represents each point. Each GUI object is associated with the BO corresponding object. When T changes GUI P captures the Changed event and changes its location. So, when G should be modified, it modifies internally its objects and as result T changes, P moves and the GuiG visually changes, everything is OK. But there is an inconvenient of this architecture... BO should not be recreated, because this will breack the link between BO and GUIO. In particular, GUI P should always have the same reference of T. If in a business logic I do by e.g. P1.T = new T(this.T + 10) GUI_P1 will not move anymore, because it wait an event from the reference of former P1.T object, that does not belongs to P1 anymore. So the solution was to always modify the existing objects, not to recreate it. But here is an other inconvenient: performance. Say I have a ready newC object that should replace the older one. Instead of doing G1.C = newC I should do foreach T in foreach P in C replace with T from P from newC. Is there an other more optimal way to do it?

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  • High Runtime for Dictionary.Add for a large amount of items

    - by aaginor
    Hi folks, I have a C#-Application that stores data from a TextFile in a Dictionary-Object. The amount of data to be stored can be rather large, so it takes a lot of time inserting the entries. With many items in the Dictionary it gets even worse, because of the resizing of internal array, that stores the data for the Dictionary. So I initialized the Dictionary with the amount of items that will be added, but this has no impact on speed. Here is my function: private Dictionary<IdPair, Edge> AddEdgesToExistingNodes(HashSet<NodeConnection> connections) { Dictionary<IdPair, Edge> resultSet = new Dictionary<IdPair, Edge>(connections.Count); foreach (NodeConnection con in connections) { ... resultSet.Add(nodeIdPair, newEdge); } return resultSet; } In my tests, I insert ~300k items. I checked the running time with ANTS Performance Profiler and found, that the Average time for resultSet.Add(...) doesn't change when I initialize the Dictionary with the needed size. It is the same as when I initialize the Dictionary with new Dictionary(); (about 0.256 ms on average for each Add). This is definitely caused by the amount of data in the Dictionary (ALTHOUGH I initialized it with the desired size). For the first 20k items, the average time for Add is 0.03 ms for each item. Any idea, how to make the add-operation faster? Thanks in advance, Frank

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  • Field Members vs Method Variables?

    - by Braveyard
    Recently I've been thinking about performance difference between class field members and method variables. What exactly I mean is in the example below : Lets say we have a DataContext object for Linq2SQL class DataLayer { ProductDataContext context = new ProductDataContext(); public IQueryable<Product> GetData() { return context.Where(t=>t.ProductId == 2); } } In the example above, context will be stored in heap and the GetData method variables will be removed from Stack after Method is executed. So lets examine the following example to make a distinction : class DataLayer { public IQueryable<Product> GetData() { ProductDataContext context = new ProductDataContext(); return context.Where(t=>t.ProductId == 2); } } (*1) So okay first thing we know is if we define ProductDataContext instance as a field, we can reach it everywhere in the class which means we don't have to create same object instance all the time. But lets say we are talking about Asp.NET and once the users press submit button the post data is sent to the server and the events are executed and the posted data stored in a database via the method above so it is probable that the same user can send different data after one another.If I know correctly after the page is executed, the finalizers come into play and clear things from memory (from heap) and that means we lose our instance variables from memory as well and after another post, DataContext should be created once again for the new page cycle. So it seems the only benefit of declaring it publicly to the whole class is the just number one text above. Or is there something other? Thanks in advance... (If I told something incorrect please fix me.. )

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  • How to efficiently convert String, integer, double, datetime to binary and vica versa?

    - by Ben
    Hi, I'm quite new to C# (I'm using .NET 4.0) so please bear with me. I need to save some object properties (their properties are int, double, String, boolean, datetime) to a file. But I want to encrypt the files using my own encryption, so I can't use FileStream to convert to binary. Also I don't want to use object serialization, because of performance issues. The idea is simple, first I need to somehow convert objects (their properties) to binary (array), then encrypt (some sort of xor) the array and append it to the end of the file. When reading first decrypt the array and then somehow convert the binary array back to object properties (from which I'll generate objects). I know (roughly =) ) how to convert these things by hand and I could code it, but it would be useless (too slow). I think the best way would be just to get properties' representation in memory and save that. But I don't know how to do it using C# (maybe using pointers?). Also I though about using MemoryStream but again I think it would be inefficient. I am thinking about class Converter, but it does not support toByte(datetime) (documentation says it always throws exception). For converting back I think the only options is class Converter. Note: I know the structure of objects and they will not change, also the maximum String length is also known. Thank you for all your ideas and time. EDIT: I will be storing only parts of objects, in some cases also parts of different objects (a couple of properties from one object type and a couple from another), thus I think that serialization is not an option for me.

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