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• Can i use Twig and Doctrine in my project which is licensed under GPL license?

  - by aRagnis

  Can i license my open sourced CMS under GPL v2/v3 license if it uses Twig (BSD License) and Doctrine (LGPL)? And i also want to know, that do i have to put this text to teh beginning of all my source files... * This file is part of Foobar. * * Foobar is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * Foobar is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with Foobar. If not, see <http://www.gnu.org/licenses/>. ..or can i do it like phpbb does? /** * * @package mcp * @version $Id$ * @copyright (c) 2005 phpBB Group * @license http://opensource.org/licenses/gpl-license.php GNU Public License * */

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• Is .NET 4.0 just a show?

  - by Will Marcouiller

  I went to a presentation about the .NET Framework and Visual Studio 2010, last night. The topis were: ASP.NET 4 - Some of the new features of ASP.NET 4 More control over ClientID's in WebForms; Output Caching; ... // Some other stuff I don't really remember being more in framework and WinForms world. Entity Framework 2.0 (.NET 4.0) T4 Templates; Domain driven development; Data driven development; Contexts (edmx files); Some of real-world limitations of EF4 (projects with over 70 to 75 tables); Better POCO support, despite there are still these hidden EntityObject and StructuralObject, but used differently in comparison to EF 1.0 so that it doesn't take off your inheritance; Allows to easily choose how to persist the hierarchy into the underlying database; Code only (start working with EF4 directly from your code!); Design by Contract (DbC). The most interesting feature is, and only, as far as I'm concerned, all related to parallelism made easier. Which really works! No additional assembly references to add. In conclusion, I'm far from impressed about .NET Framework 4.0, apart that it makes some things easier to do. But when you're used to make it a way, it doesn't really change much, in my opinion. Is it me who cannot foresee what .NET 4.0 has to offer? What would you guys base your decision on to migrate to .NET 4.0, in a practical way?

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• Flushing writes in buffer of Memory Controller to DDR device

  - by Rohit

  At some point in my code, I need to push the writes in my code all the way to the DIMM or DDR device. My requirement is to ensure the write reaches the row,ban,column of the DDR device on the DIMM. I need to read what I've written to the main memory. I do not want caching to get me the value. Instead after writing I want to fetch this value from main memory(DIMM's). So far I've been using Intel's x86 instruction wbinvd(write back and invalidate cache). However this means the caches and TLB are flushed. Write-back requests go to the main memory. However, there is a reasonable amount of time this data might reside in the write buffer of the Memory Controller( Intel calls it integrated memory controller or IMC). The Memory Controller might take some more time depending on the algorithm that runs in the Memory Controller to handle writes. Is there a way I force all existing or pending writes in the write buffer of the memory controller to the DRAM devices ?? What I am looking for is something more direct and more low-level than wbinvd. If you could point me to right documents or specs that describe this I would be grateful. Generally, the IMC has a several registers which can be written or read from. From looking at the specs for that for the chipset I could not find anything useful. Thanks for taking the time to read this.

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• How to specify MQ channel table location for .net web application using web.config

  - by Matt

  I've been going around in circles for a while on this one now. I'm trying to connect to a distributed queue manager using a supplied channel table file. I can get this to work if I specify the environmental variable MQCHLLIB and MQCHLTAB on my server. However the IBM documentation states that the .net config file can override these variables. Here is what I have placed in my web.config file: ... <configSections> <section name="CHANNELS" type="System.Configuration.NameValueSectionHandler" /> </configSections> <CHANNELS> <add key="ChannelDefinitionDirectory" value="C:\temp"></add> <add key="ChannelDefinitionFile" value="DSM_MOM_TEST.tab"></add> </CHANNELS> ... And here is the code that is executing: Hashtable properties = new Hashtable(); //Add managed connection type to parameters. const String connectionType = MQC.TRANSPORT_MQSERIES_CLIENT; properties.Add(MQC.TRANSPORT_PROPERTY, connectionType); return new MQQueueManager(queueManagerName, properties); queueManagerName is set to the generic queue manager "*Q101T". However this isn't working and I get an error returned: 2058 MQRC_Q_MGR_NAME_ERROR I've been unable to find any more documentation on how to get this to work other than the environmental variables and the standard mqclient.ini should be overriden by the channels stanza in the web.config. Is there something that I've missed in the code? Any tips would be greatly appreciated.

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• SQL Server service broker reporting as off when I have written a query to turn it on

  - by dotnetdev

  I have made a small ASP.NET website. It uses sqlcachedependency The SQL Server Service Broker for the current database is not enabled, and as a result query notifications are not supported. Please enable the Service Broker for this database if you wish to use notifications. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.InvalidOperationException: The SQL Server Service Broker for the current database is not enabled, and as a result query notifications are not supported. Please enable the Service Broker for this database if you wish to use notifications. Source Error: Line 12: System.Data.SqlClient.SqlDependency.Start(connString); This is the erroneous line in my global.asax. However, in sql server (2005), I enabled service broker like so (I connect and run the SQL Server service when I debug my site): ALTER DATABASE mynewdatabase SET ENABLE_BROKER with rollback immediate And this was successful. What am I missing? I am trying to use sql caching dependency and have followed all procedures. Thanks

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• Open-sourcing a web site with active users?

  - by Lars Yencken

  I currently run several research-related web-sites with active users, and these sites use some personally identifying information about these users (their email address, IP address, and query history). Ideally I'd release the code to these sites as open source, so that other people could easily run similar sites, and more importantly scrutinise and replicate my work, but I haven't been comfortable doing so, since I'm unsure of the security implications. For example, I wouldn't want my users' details to be accessed or distributed by a third party who found some flaw in my site, something which might be easy to do with full source access. I've tried going half-way by refactoring the (Django) site into more independent modules, and releasing those, but this is very time consuming, and in practice I've never gotten around to releasing enough that a third party can replicate the site(s) easily. I also feel that maybe I'm kidding myself, and that this process is really no different to releasing the full source. What would you recommend in cases like this? Would you open-source the site and take the risk? As an alternative, would you advertise the source as "available upon request" to other researchers, so that you at least know who has the code? Or would you just apologise to them and keep it closed in order to protect users?

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• Best practices for withstanding launch day traffic burst

  - by Sam McAfee

  We are working on a website for a client that (for once) is expected to get a fair amount of traffic on day one. There are press releases, people are blogging about it, etc. I am a little concerned that we're going to fall flat on our face on day one. What are the main things you would look at to ensure (in advance without real traffic data) that you can stay standing after a big launch. Details: This is a L/A/M/PHP stack, using an internally developed MVC framework. This is currently being launched on one server, with Apache and MySQL both on it, but we can break that up if need be. We are already installing memcached and doing as much PHP-level caching as we can think of. Some of the pages are rather query intensive, and we are using Smarty as our template engine. Keep in mind there is no time to change any of these major aspects--this is the just the setup. What sorts of things should we watch out for?

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• How Can I Find What's Causing My Transaction to Get Promoted?

  - by Damian Powell

  I have web site which serves web services (a mixture of .asmx and WCF) which is mostly using LINQ to SQL and System.Transactions. Occaisionally we see the transaction get promoted to a distributed transaction which causes problems because our web servers are isolated from our databases in such a way that it is not possible for us to use MSDTC. I have configured tracing for System.Transactions by adding the following to my web.config: <system.diagnostics> <sources> <source name="System.Transactions" switchValue="Information"> <listeners> <add name="tx" type="System.Diagnostics.XmlWriterTraceListener" initializeData="tx.log" /> </listeners> </source> </sources> </system.diagnostics> It's very interesting and shows me when the transaction is promoted, but I find that it doesn't really help be discover why. Is there an equivalent tracing mechanism for ADO.NET that will show me when connections are created, including the variables that affect pooling (user, cnn string, transaction scope)?

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• Amazon Product API ResponseGroups and Default results

  - by aboxy

  A. In our application, most of the data we work with is stored as free text .i.e. there is no categorization done as of now. We are using openNLP libraries to make sense of the data(extract keywords/classify) and do a query to Amazon web services to pull the results of the query. We use searchindex=All and keywords=. Results are not always returned and we basically get 'AWS.ECommerceService.NoExactMatches' How to avoid that? 1) Is there a way to specify default results if no match found? e.g. Amazon carousel widget does that if the search query did not return results, it basically show some computer items. 2) Should I batch the request always and add another search criteria to every request? If my first criteria does not pull any results, we can be sure that our 2nd query will always pull results(possibly caching?) Here is one search criteria 'Open Circle Hoop Earrings Polished Stainless Steel Open Circle Hoop Earrings Polished Stainless Steel DiamondShark' This return no results via API. On Amazon site,I get alternative suggestions with some results which are pretty relevant. Is there a way to pull those results? B. We just need a thumbnail image and a title and description for our app. Which responseGroup is appropriate? We are using medium rt now but there is awful lot of information even with that responseGroup. Any help is appreciated. thanks

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• Is it poor design to create objects that only execute code during the constructor?

  - by Curtix

  In my design I am using objects that evaluate a data record. The constructor is called with the data record and type of evaluation as parameters and then the constructor calls all of the object's code necessary to evaluate the record. This includes using the type of evaluation to find additional parameter-like data in a text file. There are in the neighborhood of 250 unique evaluation types that use the same or similar code and unique parameters coming from the text file. Some of these evaluations use different code so I benefit a lot from this model because I can use inheritance and polymorphism. Once the object is created there isn't any need to execute additional code on the object (at least for now) and it is used more like a struct; its kept on a list and 3 properties are used later. I think this design is the easiest to understand, code, and read. A logical alternative I guess would be using functions that return score structs, but you can't inherit from methods so it would make it kind of sloppy imo. I am using vb.net and these classes will be used in an asp.net web app as well as in a distributed app. thanks for your input

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• C# wrapper for objects

  - by Haggai

  I'm looking for a way to create a generic wrapper for any object. The wrapper object will behave just like the class it wraps, but will be able to have more properties, variable, methods etc., for e.g. object counting, caching etc. Say the wrapper class be called Wrapper, and the class to be wrapped be called Square and has the constructor Square(double edge_len) and the properties/methods EdgeLength and Area, I would like to use it as follows: Wrapper<Square> mySquare = new Wrapper<Square>(2.5); /* or */ new Square(2.5); Console.Write("Edge {0} -> Area {1}", mySquare.EdgeLength, mySquare.Area); Obviously I can create such a wrapper class for each class I want to wrap, but I'm looking for a general solution, i.e. Wrapper<T> which can handle both primitive and compound types (although in my current situation I would be happy with just wrapping my own classes). Suggestions? Thanks.

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• UnauthorizedAccessException when running desktop application from shared folder

  - by Atara

  I created a desktop application using VS 2008. When I run it locally, all works well. I shared my output folder (WITHOUT allowing network users to change my files) and ran my exe from another Vista computer on our intranet. When running the shared exe, I receive "System.UnauthorizedAccessException" when trying to read a file. How can I give permission to allow reading the file? Should I change the code? Should I grant permission to the application\folder on the Vista computer? how? Notes: I do not use ClickOnce. the application should be distributed using xcopy. My application target framework is ".Net Framework 2.0" On the Vista computer, "controlPanel | UninstallOrChangePrograms" it says it has "Microsoft .Net Framework 3.5 SP1" I also tried to map the folder drive, but got the same errors, only now the fileName is "T:\my.ocx" ' ---------------------------------------------------------------------- ' my code: Dim src As String = mcGlobals.cmcFiles.mcGetFileNameOcx() Dim ioStream As New System.IO.FileStream(src, IO.FileMode.Open) ' ---------------------------------------------------------------------- Public Shared Function mcGetFileNameOcx() As String ' ---------------------------------------------------------------------- Dim dirName As String = Application.StartupPath & "\" Dim sFiles() As String = System.IO.Directory.GetFiles(dirName, "*.ocx") Dim i As Integer For i = 0 To UBound(sFiles) Debug.WriteLine(System.IO.Path.GetFullPath(sFiles(i))) ' if found any - return the first: Return System.IO.Path.GetFullPath(sFiles(i)) Next Return "" End Function ' ---------------------------------------------------------------------- ' The Exception I receive: System.UnauthorizedAccessException: Access to the path '\\computerName\sharedFolderName\my.ocx' is denied. at System.IO._Error(Int32 errorCode, String maybeFullPath) at System.IO.FileStream.Init(...) at System.IO.FileStream..ctor(...) at System.IO.FileStream..ctor(String path, FileMode mode) ' ----------------------------------------------------------------------

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• hosting a high traffic facebook app (game)

  - by z3cko

  we are currently developing a high traffic facebook application. all the traffic will be within one month, where there are 500.000 to 1.000.000 expected users. after that month, the game is over and we have a winner - so the app will be archived. we are currently planning to develop the application with ruby on rails and searching for hosting options that can deal with the traffic. the problem is not so much the users, but the peak values: we will have around 500.000 requests coming daily within a short timeframe (lets say within 3 minutes in the worst case) we are expecting 500.000 to 1.000.000 users of the application, with peaks at 1:00pm (timezone GMT+1), where most (up to 80% of the users) will send most of the requests. the requests are from 11th of june to 11.july - after that, the app/game is closed/over. we are currently developing an aggressive caching mechanism - currently we are thinking about 2 or 3 small apps/webservices, that will handle the load. the load is distributed as follows: a) main application, cached data (11 screens, 200k each) b) voting: every day until 1:00pm (timezone GMT+1) - every user votes with about 10k data sent, high concurrent peak values! questions: is there any specific application setup that is recommendable? are there any hosting partners that can be recommended? thanks!

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• Firefox extension js object initialization

  - by Michael

  Note: this is about Firefox extension, not a js general question. In Firefox extension project I need my javascript object to be initialized just once per Firefox window. Otherwise each time I open my window a new timers will be engaged, new properties will be used, so everything will start from scratch. hope example below will demystify my question :) var StupidExtension { statusBarValue: "Not Initialized Yet", startup: function () { ... // Show statusBarValue in Status Bar Panel }, initTimerToRetrieveStatusBarValueFromNetwork: function () { ... } } so each time you hit Ctrl+N a new window you will see "Not Initialized Yet" and then new timer will be fired, so after some time it retrieve data from network you will see value also on second window and so on. Ideally would be to have just a single timer function running and updating all status bar panels in all Firefox windows. Of course I can do some caching, like saving the value in prefs or some other storage, then show it from there. But I feel like this is artificial. So the question will be is there "native" technique of making static some parts of the object among all Firefox window instances?

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• How to implement Administrator rights in Java Application?

  - by Yatendra Goel

  I am developing a Data Modeling Software that is implemented in Java. This application converts the textual data (stored in a database) to graphical form so that users can interpret the data in a more efficient form. Now, this application will be accessed by 3 kinds of persons: 1. Managers (who can fill the database with data and they can also view the visual form of the data after entering the data into the database) 2. Viewers (who can only view the visual form of data that has been filled by managers) 3. Administrators (who can create and manage other administrators, managers and viewers) Now, how to implement 3 diff. views of the same application. Note: Managers, Viewers and Administrators can be located in any part of the world and should access the application through internet. One idea that came in my mind is as follows: Step1: Code all the business logic in EJBs so that it can be used in distributed environment (means which can be accessed by several users through internet) Step2: Code 3 Swing GUI Clients: One for administrators, one for managers and one for viewers. These 3 GUI clients can access business logic written in EJBs. Step3: Distribute the clients corresponding to their users. For instance, manager client to managers. =================================QUESTIONS======================================= Q1. Is the above approach is correct? Q2. This is very common functionality that various softwares have. So, Do they implement this kind of functionality through this way or any other way? Q3. If any other approach would be more better, then what is that approach?

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• Telerik chart not loading correctly in new window (ajax issue?)

  - by Phillip Schmidt

  I have a page which contains user controls with Telerik Charts (grids also, but they work fine). From this page, the user can click on a button to be redirected to a "Printer-Friendly Version" type page, which opens a new window via javascript and goes through a slightly different view (for formatting and stuff), but the telerik code is all the same. The problem is, my Chart displays just fine in the original window, but the new window displays basically an empty chart with no data. This bug is only present in IE, and only applies to Charts. Grids work fine, for whatever reason. I'm thinking this is due to differences in script caching between browsers -- correct me if I'm wrong, I'm semi-new to client-directed web development. Anyway I read somewhere that Telerik has issues with loading data and/or js files when loaded via ajax, so maybe that's the problem? If so, how could I get around this? And if not, any ideas on what could be causing this issue? It's causing me a great deal of frustration, since a print preview page seems like it should be the easiest of jobs. Edit: The charts are being rendered as html (if somebody can explain how to render them as images, that would be awesome). And dev tools shows basically the same thing between chrome and IE. Whenever my web service goes back up ill WinMerge them and look for any peculiarities/differences between them. In the mean time, though, the "render as an image" concept sounds promising. That way I could just save the image from the first page, and insert it right into the print preview page, right?. And since it's a print-preview page, it's not going to need to be interactive or anything, so that'd work out nicely. Another (important) Edit: These are probably the culprit... And here is a little more detail on that: And here is a side-by-side of it working(in chrome) and not working (in IE):

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• Zend Framework - Deny access to folders other than public folder

  - by Vincent

  All, I have the following Zend application structure: helloworld - application - configs - controllers - models - layouts - include - library - public - .htaccess - index.php - design - .htaccess The .htaccess in the root folder has the following contents: ##################################################### # CONFIGURE media caching # Header unset ETag FileETag None Header unset Last-Modified Header set Expires "Fri, 21 Dec 2012 00:00:00 GMT" Header set Cache-Control "max-age=7200, must-revalidate" SetOutputFilter DEFLATE # ##################################################### ErrorDocument 404 /custom404.php RedirectMatch permanent ^/$ /public/ The .htaccess in the public folder has the following: Options -MultiViews ErrorDocument 404 /custom404.php RewriteEngine on # The leading %{DOCUMENT_ROOT} is necessary when used in VirtualHost context RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} -s [OR] RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} -l [OR] RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} -d RewriteRule ^.*$ - [NC,L] RewriteRule ^.*$ index.php [NC,L] My vhost configuration is as under: <VirtualHost *:80> ServerAdmin [email protected] DocumentRoot "C:\\xampp\\htdocs\\xampp\\helloworld\\" ServerName helloworld ServerAlias helloworld <Directory "C:\\xampp\\htdocs\\xampp\\helloworld\\"> Options Indexes FollowSymLinks AllowOverride all Order Deny,Allow Deny from all Allow from 127.0.0.1 </Directory> </VirtualHost> Currently, if the user visits, http://localhost, my .htaccess files above make sure, the request is routed to http://localhost/public automatically. If the user visits any other folder apart from public folder from the address bar, he gets a directory listing of that folder. How can I make sure to deny the user access to every other folder except the public folder? I want the user to be redirected to the public folder if he visits any other folder. However, if the underlying code requests something from other folders, (ex: ) it should still work.. Thanks

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• Java: fastest way to do random reads on huge disk file(s)

  - by cocotwo

  I've got a moderately big set of data, about 800 MB or so, that is basically some big precomputed table that I need to speed some computation by several orders of magnitude (creating that file took several mutlicores computers days to produce using an optimized and multi-threaded algo... I do really need that file). Now that it has been computed once, that 800MB of data is read only. I cannot hold it in memory. As of now it is one big huge 800MB file but splitting in into smaller files ain't a problem if it can help. I need to read about 32 bits of data here and there in that file a lot of time. I don't know before hand where I'll need to read these data: the reads are uniformly distributed. What would be the fastest way in Java to do my random reads in such a file or files? Ideally I should be doing these reads from several unrelated threads (but I could queue the reads in a single thread if needed). Is Java NIO the way to go? I'm not familiar with 'memory mapped file': I think I don't want to map the 800 MB in memory. All I want is the fastest random reads I can get to access these 800MB of disk-based data. btw in case people wonder this is not at all the same as the question I asked not long ago: http://stackoverflow.com/questions/2346722/java-fast-disk-based-hash-set

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• gwt seperate modules with no code sharing

  - by Code freak

  Hi, I have to make a web application using GWT. The project has a core module that'll expose a set of apis to be used by other apps; each of these app are unrelated. Each shall be loaded in a separate iframe. My idea was to compile core into core.js and each app shall have its own app1.js app2.js and so on... App1 script type="text/javascript" src="core.js" ></script> script type="text/javascript" src="app1.js" ></script> with this design, due to browser caching, each app laod only the app.js which should be smaller ~20kb in size. Making a core module is straightforward but the apps are problematic. The reason being after compilation, each app contains the entire GWT library - this substantially increases the download size of the complete webapp. Can anyone suggest a way to get aroung this problem ? I've checked similar questions on SO, but failed to find a simple working answer fr the problem. Thanks for any help.

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• Django Model Formset Pre-Filled Value Problem

  - by user552377

  Hi, i'm trying to use model formsets with Django. When i load forms template, i see that it's filled-up with previous values. Is there a caching mechanism that i should stop, or what? Thanks for your help, here is my code: models.py class FooModel( models.Model ): a_field = models.FloatField() b_field = models.FloatField() def __unicode__( self ): return self.a_field forms.py from django.forms.models import modelformset_factory FooFormSet = modelformset_factory(FooModel) views.py def foo_func(request): if request.method == 'POST': formset = FooFormSet(request.POST, request.FILES, prefix='foo_prefix' ) if formset.is_valid(): formset.save() return HttpResponseRedirect( '/true/' ) else: return HttpResponseRedirect( '/false/' ) else: formset = FooFormSet(prefix='foo_prefix') variables = RequestContext( request , { 'formset':formset , } ) return render_to_response('footemplate.html' , variables ) template: <form method="post" action="."> {% csrf_token %} <input type="submit" value="Submit" /> <table id="FormsetTable" border="0" cellpadding="0" cellspacing="0"> <tbody> {% for form in formset.forms %} <tr> <td>{{ form.a_field }}</td> <td>{{ form.b_field }}</td> </tr> {% endfor %} </tbody> </table> {{ formset.management_form }} </form>

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• Mutually beneficial IP/copyright clauses for contract-based freelance work

  - by Nathan de Vries

  I have a copyright section in the contract I give to my clients stating that I retain copyright on any works produced during my work for them as an independent contractor. This is most definitely not intended to place arbitrary restrictions on my clients, but rather to maintain my ability to decide on how the software I create is licensed and distributed. Almost every project I work on results in at least one part of it being released as open source. Every project I work on makes use of third-party software released in the same fashion, so returning the favour is something I would like to continue doing. Unfortunately, the contract is not so clear when it comes to defining the rights of the client in the use of said software. I mention that the code will be licensed to them, but do not mention specifics about exclusivity, ability to produce derivatives etc. As such, a client has raised concerns about the copyright section of my contract, and has suggested that I reword it such that all copyrights are transferred entirely to the client on final payment for the project. This will almost certainly reduce my ability to distribute the software I have created; I would much prefer to find a more mutually beneficial agreement where both our concerns are appeased. Are there any tried and true approaches to licensing software in this kind of situation? To summarise: I want to maintain the ability to license (parts of) the software under my own terms, independently of my relationship with the client; with some guarantee to the client that no trade-secrets or critical business logic will be shared; giving them the ability to re-use my code in their future projects; but not necessarily letting them sell it (I'm not sure about this, though...what happens if they sell their business and the software along with it?) I realise that everyone's feedback is going to be prefixed with "IANAL", however I appreciate any thoughts you might have on the matter.

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• The way cores, processes, and threads work exactly?

  - by unknownthreat

  I need a bit of an advice for understanding how this whole procedure work exactly. If I am incorrect in any part described below, please correct me. In a single core CPU, it runs each process in the OS, jumping around from one process to another to utilize the best of itself. A process can also have many threads, in which the CPU core runs through these threads when it is running on the respective process. Now, on a multiple core CPU, Do the cores run in every process together, or can the cores run separately in different processes at one particular point of time? For instance, you have program A running two threads, can a duo core CPU run both threads of this program? I think the answer should be yes if we are using something like OpenMP. But while the cores are running in this OpenMP-embedded process, can one of the core simply switch to other process? For programs that are created for single core, when running at 100%, why the CPU utilization of each core are distributed? (ex. A duo core CPU of 80% and 20%. The utilization percentage of all cores always add up to 100% for this case.) Do the cores try help each other run each thread of each process in some ways? Frankly, I'm not sure how this works exactly. Any advice is appreciated.

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• How do I implement Hibernate Pagination using a cursor (so the results stay consistent, despite new

  - by hunterae

  Hey all, Is there any way to maintain a database cursor using Hibernate between web requests? Basically, I'm trying to implement pagination, but the data that is being paged is consistently changing (i.e. new records are added into the database). We are trying to set it up such that when you do your initial search (returning a maximum of 5000 results), and you page through the results, those same records always appear on the same page (i.e. we're not continuously running the query each time next and previous page buttons are clicked). The way we're currently implementing this is by merely selecting 5000 (at most) primary keys from the table we're paging, storing those keys in memory, and then just using 20 primary keys at a time to fetch their details from the database. However, we want to get away from having to store these keys in memory and would much prefer a database cursor that we just keep going back to and moving backwards and forwards over the cursor to generate pages. I tried doing this with Hibernate's ScrollableResults but found that I could not call methods like next() and previous() would cause an exception if you within a different web request / Hibernate session (no surprise there). Is there any way to reattach a ScrollableResults object to a Session, much the same way you would reattach a detached database object to make it persistent? Are there any other approaches to implement this data paging with consistent paging results without caching the primary keys?

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• What about parallelism across network using multiple PCs?

  - by MainMa

  Parallel computing is used more and more, and new framework features and shortcuts make it easier to use (for example Parallel extensions which are directly available in .NET 4). Now what about the parallelism across network? I mean, an abstraction of everything related to communications, creation of processes on remote machines, etc. Something like, in C#: NetworkParallel.ForEach(myEnumerable, () => { // Computing and/or access to web ressource or local network database here }); I understand that it is very different from the multi-core parallelism. The two most obvious differences would probably be: The fact that such parallel task will be limited to computing, without being able for example to use files stored locally (but why not a database?), or even to use local variables, because it would be rather two distinct applications than two threads of the same application, The very specific implementation, requiring not just a separate thread (which is quite easy), but spanning a process on different machines, then communicating with them over local network. Despite those differences, such parallelism is quite possible, even without speaking about distributed architecture. Do you think it will be implemented in a few years? Do you agree that it enables developers to easily develop extremely powerfull stuff with much less pain? Example: Think about a business application which extracts data from the database, transforms it, and displays statistics. Let's say this application takes ten seconds to load data, twenty seconds to transform data and ten seconds to build charts on a single machine in a company, using all the CPU, whereas ten other machines are used at 5% of CPU most of the time. In a such case, every action may be done in parallel, resulting in probably six to ten seconds for overall process instead of forty.

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• C++ STL Map vs Vector speed

  - by sub

  In the interpreter for my experimental programming language I have a symbol table. Each symbol consists of a name and a value (the value can be e.g.: of type string, int, function, etc.). At first I represented the table with a vector and iterated through the symbols checking if the given symbol name fitted. Then I though using a map, in my case map<string,symbol>, would be better than iterating through the vector all the time but: It's a bit hard to explain this part but I'll try. If a variable is retrieved the first time in a program in my language, of course its position in the symbol table has to be found (using vector now). If I would iterate through the vector every time the line gets executed (think of a loop), it would be terribly slow (as it currently is, nearly as slow as microsoft's batch). So I could use a map to retrieve the variable: SymbolTable[ myVar.Name ] But think of the following: If the variable, still using vector, is found the first time, I can store its exact integer position in the vector with it. That means: The next time it is needed, my interpreter knows that it has been "cached" and doesn't search the symbol table for it but does something like SymbolTable.at( myVar.CachedPosition ). Now my (rather hard?) question: Should I use a vector for the symbol table together with caching the position of the variable in the vector? Should I rather use a map? Why? How fast is the [] operator? Should I use something completely different?

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