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  • Calculating IOPS for a single HDD - what am I doing wrong?

    - by red888
    So I know there is no standardized way of calculating IOPS for a HDD, but from everything I have read it appears one of the most accurate formulas is the following: IOP/ms = + {rotational latency} + ({block size} / {data transfer rate}) Which is IOs per millisecond or what the book I've been reading calls "Disk Service Time". Also rotational latency is calculated as half of one rotation in milliseconds. This was taken from the EMC book "Information Storage and Management" -arguably a pretty reliable source right\wrong? Putting this formula into practice consider this Seagate data sheet. I am going to calculate IOPS for the ST3000DM001 model for a block size of 4kb: Seek Average (Write) = 9.5 -I'll measuring IOPS for writes Spindle speed = 7200rpm Average Data Rate = 156MB/s So my variables are: Seek Time = 9.5ms Rotational latency = (.5 / (7200rpm / 60)) = 0.004s = 4ms Data Rate = 156MB/s = (0.156MB/ms / 0.004MB) = 39 9.5ms + 4ms + 39 = IO/ms 52.5 1 / (52.5 * 0.001) = 19 IOPS 19 IOPS for this drive clearly is not right so what am I doing wrong?

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  • How to include multiple XML files in a single XML file for deserialization by XmlSerializer in .NET

    - by harrydev
    Hi, is it possible to use the XmlSerializer in .NET to load an XML file which includes other XML files? And how? This, in order to share XML state easily in two "parent" XML files, e.g. AB and BC in below. Example: using System; using System.IO; using System.Xml.Serialization; namespace XmlSerializerMultipleFilesTest { [Serializable] public class A { public int Value { get; set; } } [Serializable] public class B { public double Value { get; set; } } [Serializable] public class C { public string Value { get; set; } } [Serializable] public class AB { public A A { get; set; } public B B { get; set; } } [Serializable] public class BC { public B B { get; set; } public C C { get; set; } } class Program { public static void Serialize<T>(T data, string filePath) { using (var writer = new StreamWriter(filePath)) { var xmlSerializer = new XmlSerializer(typeof(T)); xmlSerializer.Serialize(writer, data); } } public static T Deserialize<T>(string filePath) { using (var reader = new StreamReader(filePath)) { var xmlSerializer = new XmlSerializer(typeof(T)); return (T)xmlSerializer.Deserialize(reader); } } static void Main(string[] args) { const string fileNameA = @"A.xml"; const string fileNameB = @"B.xml"; const string fileNameC = @"C.xml"; const string fileNameAB = @"AB.xml"; const string fileNameBC = @"BC.xml"; var a = new A(){ Value = 42 }; var b = new B(){ Value = Math.PI }; var c = new C(){ Value = "Something rotten" }; Serialize(a, fileNameA); Serialize(b, fileNameB); Serialize(c, fileNameC); // How can AB and BC be deserialized from single // files which include two of the A, B or C files. // Using ideally something like: var ab = Deserialize<AB>(fileNameAB); var bc = Deserialize<BC>(fileNameBC); // That is, so that A, B, C xml file // contents are shared across these two } } } Thus, the A, B, C files contain the following: A.xml: <?xml version="1.0" encoding="utf-8"?> <A xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Value>42</Value> </A> B.xml: <?xml version="1.0" encoding="utf-8"?> <B xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Value>3.1415926535897931</Value> </B> C.xml: <?xml version="1.0" encoding="utf-8"?> <C xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Value>Something rotten</Value> </C> And then the "parent" XML files would contain a XML include file of some sort (I have not been able to find anything like this), such as: AB.xml: <?xml version="1.0" encoding="utf-8"?> <AB xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <A include="A.xml"/> <B include="B.xml"/> </AB> BC.xml: <?xml version="1.0" encoding="utf-8"?> <BC xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <B include="B.xml"/> <C include="C.xml"/> </BC> Of course, I guess this can be solved by implementing IXmlSerializer for AB and BC, but I was hoping there was an easier solution or a generic solution with which classes themselves only need the [Serializable] attribute and nothing else. That is, the split into multiple files is XML only and handled by XmlSerializer itself or a custom generic serializer on top of this. I know this should be somewhat possible with app.config (as in http://stackoverflow.com/questions/480538/use-xml-includes-or-config-references-in-app-config-to-include-other-config-files), but I would prefer a solution based on XmlSerializer. Thanks.

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  • Cloud MBaaS : The Next Big Thing in Enterprise Mobility

    - by shiju
    In this blog post, I will take a look at Cloud Mobile Backend as a Service (MBaaS) and how we can leverage Cloud based Mobile Backend as a Service for building enterprise mobile apps. Today, mobile apps are incredibly significant in both consumer and enterprise space and the demand for the mobile apps is unbelievably increasing in day to day business. An enterprise can’t survive in business without a proper mobility strategy. A better mobility strategy and faster delivery of your mobile apps will give you an extra mileage for your business and IT strategy. So organizations and mobile developers are looking for different strategy for meeting this demand and adopting different development strategy for their mobile apps. Some developers are adopting hybrid mobile app development platforms, for delivering their products for multiple platforms, for fast time-to-market. Others are adopting a Mobile enterprise application platform (MEAP) such as Kony for their enterprise mobile apps for fast time-to-market and better business integration. The Challenges of Enterprise Mobility The real challenge of enterprise mobile apps, is not about creating the front-end environment or developing front-end for multiple platforms. The most important thing of enterprise mobile apps is to expose your enterprise data to mobile devices where the real pain is your business data might be residing in lot of different systems including legacy systems, ERP systems etc., and these systems will be deployed with lot of security restrictions. Exposing your data from the on-premises servers, is not a easy thing for most of the business organizations. Many organizations are spending too much time for their front-end development strategy, but they are really lacking for building a strategy on their back-end for exposing the business data to mobile apps. So building a REST services layer and mobile back-end services, on the top of legacy systems and existing middleware systems, is the key part of most of the enterprise mobile apps, where multiple mobile platforms can easily consume these REST services and other mobile back-end services for building mobile apps. For some mobile apps, we can’t predict its user base, especially for products where customers can gradually increase at any time. And for today’s mobile apps, faster time-to-market is very critical so that spending too much time for mobile app’s scalability, will not be worth. The real power of Cloud is the agility and on-demand scalability, where we can scale-up and scale-down our applications very easily. It would be great if we could use the power of Cloud to mobile apps. So using Cloud for mobile apps is a natural fit, where we can use Cloud as the storage for mobile apps and hosting mechanism for mobile back-end services, where we can enjoy the full power of Cloud with greater level of on-demand scalability and operational agility. So Cloud based Mobile Backend as a Service is great choice for building enterprise mobile apps, where enterprises can enjoy the massive scalability power of their mobile apps, provided by public cloud vendors such as Microsoft Windows Azure. Mobile Backend as a Service (MBaaS) We have discussed the key challenges of enterprise mobile apps and how we can leverage Cloud for hosting mobile backend services. MBaaS is a set of cloud-based, server-side mobile services for multiple mobile platforms and HTML5 platform, which can be used as a backend for your mobile apps with the scalability power of Cloud. The information below provides the key features of a typical MBaaS platform: Cloud based storage for your application data. Automatic REST API services on the application data, for CRUD operations. Native push notification services with massive scalability power. User management services for authenticate users. User authentication via Social accounts such as Facebook, Google, Microsoft, and Twitter. Scheduler services for periodically sending data to mobile devices. Native SDKs for multiple mobile platforms such as Windows Phone and Windows Store, Android, Apple iOS, and HTML5, for easily accessing the mobile services from mobile apps, with better security.  Typically, a MBaaS platform will provide native SDKs for multiple mobile platforms so that we can easily consume the server-side mobile services. MBaaS based REST APIs can use for integrating to enterprise backend systems. We can use the same mobile services for multiple platform so hat we can reuse the application logic to multiple mobile platforms. Public cloud vendors are building the mobile services on the top of their PaaS offerings. Windows Azure Mobile Services is a great platform for a MBaaS offering that is leveraging Windows Azure Cloud platform’s PaaS capabilities. Hybrid mobile development platform Titanium provides their own MBaaS services. LoopBack is a new MBaaS service provided by Node.js consulting firm StrongLoop, which can be hosted on multiple cloud platforms and also for on-premises servers. The Challenges of MBaaS Solutions If you are building your mobile apps with a new data storage, it will be very easy, since there is not any integration challenges you have to face. But most of the use cases, you have to extract your application data in which stored in on-premises servers which might be under VPNs and firewalls. So exposing these data to your MBaaS solution with a proper security would be a big challenge. The capability of your MBaaS vendor is very important as you have to interact with your legacy systems for many enterprise mobile apps. So you should be very careful about choosing for MBaaS vendor. At the same time, you should have a proper strategy for mobilizing your application data which stored in on-premises legacy systems, where your solution architecture and strategy is more important than platforms and tools.  Windows Azure Mobile Services Windows Azure Mobile Services is an MBaaS offerings from Windows Azure cloud platform. IMHO, Microsoft Windows Azure is the best PaaS platform in the Cloud space. Windows Azure Mobile Services extends the PaaS capabilities of Windows Azure, to mobile devices, which can be used as a cloud backend for your mobile apps, which will provide global availability and reach for your mobile apps. Windows Azure Mobile Services provides storage services, user management with social network integration, push notification services and scheduler services and provides native SDKs for all major mobile platforms and HTML5. In Windows Azure Mobile Services, you can write server-side scripts in Node.js where you can enjoy the full power of Node.js including the use of NPM modules for your server-side scripts. In the previous section, we had discussed some challenges of MBaaS solutions. You can leverage Windows Azure Cloud platform for solving many challenges regarding with enterprise mobility. The entire Windows Azure platform can play a key role for working as the backend for your mobile apps where you can leverage the entire Windows Azure platform for your mobile apps. With Windows Azure, you can easily connect to your on-premises systems which is a key thing for mobile backend solutions. Another key point is that Windows Azure provides better integration with services like Active Directory, which makes Windows Azure as the de facto platform for enterprise mobility, for enterprises, who have been leveraging Microsoft ecosystem for their application and IT infrastructure. Windows Azure Mobile Services  is going to next evolution where you can expect some exciting features in near future. One area, where Windows Azure Mobile Services should definitely need an improvement, is about the default storage mechanism in which currently it is depends on SQL Server. IMHO, developers should be able to choose multiple default storage option when creating a new mobile service instance. Let’s say, there should be a different storage providers such as SQL Server storage provider and Table storage provider where developers should be able to choose their choice of storage provider when creating a new mobile services project. I have been used Windows Azure and Windows Azure Mobile Services as the backend for production apps for mobile, where it performed very well. MBaaS Over MEAP Recently, many larger enterprises has been adopted Mobile enterprise application platform (MEAP) for their mobile apps. I haven’t worked on any production MEAP solution, but I heard that developers are really struggling with MEAP in different way. The learning curve for a proprietary MEAP platform is very high. I am completely against for using larger proprietary ecosystem for mobile apps. For enterprise mobile apps, I highly recommend to use native iOS/Android/Windows Phone or HTML5  for front-end with a cloud hosted MBaaS solution as the middleware. A MBaaS service can be consumed from multiple mobile apps where REST APIs are using to integrating with enterprise backend systems. Enterprise mobility should start with exposing REST APIs on the enterprise backend systems and these REST APIs can host on Cloud where we can enjoy the power of Cloud for our services. If you are having REST APIs for your enterprise data, then you can easily build mobile frontends for multiple platforms.   You can follow me on Twitter @shijucv

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  • More information wanted on error: CREATE ASSEMBLY for assembly failed because assembly failed verif

    - by turnip.cyberveggie
    I have a small application that uses SQL Server 2005 Express with CLR stored procedures. It has been successfully installed and runs on many computers running XP and Vista. To create the assembly the following SQL is executed (names changed to protect the innocent): CREATE ASSEMBLY myAssemblyName FROM 'c:\pathtoAssembly\myAssembly.dll' On one computer (a test machine that reflects other computers targeted for installation) that is running Vista and has some very aggressive security policy restrictions I receive the following error: << Start Error Message Msg 6218, Level 16, State 2, Server domain\servername, Line 2 CREATE ASSEMBLY for assembly 'myAssembly' failed because assembly 'myAssembly' failed verification. Check if the referenced assemblies are up-to-date and trusted (for external_access or unsafe) to execute in the database. CLR Verifier error messages if any will follow this message [ : myProcSupport.Axis::Proc1][mdToken=0x6000004] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc2][mdToken=0x6000005] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc3][mdToken=0x6000006] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::.ctor][mdToken=0x600000a] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc4][mdToken=0x6000001] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc5][mdToken=0x6000002] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc6][mdToken=0x6000007] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc7][mdToken=0x6000008] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc8][mdToken=0x6000009] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc8][mdToken=0x600000b] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc9][mdToken=0x600000c] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation.... << End Error Message The C# DLL is defined as “Safe” as it only uses data contained in the database. The DLL is not normally signed, but I provided a signed version to test and received the same results. The installation is being done by someone else, and I don’t have access to the box, but they are executing scripts that I provided and work on other computers. I have tried to find information about this error beyond what the results of the script provide, but I haven’t found anything helpful. The person executing the script to create the assembly is logged in with an Admin account, is running CMD as admin, is connecting to the DB via Windows Authentication, has been added to the dbo_owner role, and added to the server role SysAdmin with the hopes that it is a permissions issue. This hasn't changed anything. Do I need to configure SQL Server 2005 Express differently for this environment? Is this error logged anywhere other than just the output from SQLCMD? What could cause this error? Could Vista security policies cause this? I don’t have access to the computer (the customer is doing the testing) so I can’t examine the box myself. TIA

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  • publishing asp.net website give "Object reference not set to an instance of an object." error

    - by Johan
    Good day I am using VS 2008 I am getting fed up with this error. I have search all over the web and tried every possible suggestion to this error I could find. 1. delete app_code, build, add files back, publish. (did not work) 2. delete temporary asp.net files (did not work) in the end I even tried the command line and get the following stacktrace. error ASPRUNTIME: Object reference not set to an instance of an object. [NullReferenceException]: Object reference not set to an instance of an object. at System.Web.Compilation.BuildManager.CopyPrecompiledFile(VirtualFile vfile, String destPhysicalPath) at System.Web.Compilation.BuildManager.CopyStaticFilesRecursive(VirtualDirect ory sourceVdir, String destPhysicalDir, Boolean topLevel) at System.Web.Compilation.BuildManager.CopyStaticFilesRecursive(VirtualDirect ory sourceVdir, String destPhysicalDir, Boolean topLevel) at System.Web.Compilation.BuildManager.CopyStaticFilesRecursive(VirtualDirect ory sourceVdir, String destPhysicalDir, Boolean topLevel) at System.Web.Compilation.BuildManager.PrecompileAppInternal(VirtualPath star tingVirtualDir) at System.Web.Compilation.BuildManager.PrecompileApp(VirtualPath startingVirt ualDir) at System.Web.Compilation.BuildManager.PrecompileApp(ClientBuildManagerCallba ck callback) at System.Web.Compilation.BuildManagerHost.PrecompileApp(ClientBuildManagerCa llback callback) at System.Web.Compilation.BuildManagerHost.PrecompileApp(ClientBuildManagerCa llback callback) at System.Web.Compilation.ClientBuildManager.PrecompileApplication(ClientBuil dManagerCallback callback, Boolean forceCleanBuild) at System.Web.Compilation.ClientBuildManager.PrecompileApplication(ClientBuil dManagerCallback callback) at System.Web.Compilation.Precompiler.Main(String[] args) I used the following command line: aspnet_compiler.exe -p d:\code\websites\brokerweb -v / d:\code\websites\published -f -c -errorstack -u Please help as I cannot publish this site at all at present and it worked fine for quite a long time now before this stupid error. Regards Johan

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  • Java: How to have an ArrayList as instance variable of an object?

    - by JDelage
    All, I'm working on a class project to build a little Connect4 game in Java. My current thinking is to have a class of Columns that have as instance variable a few integers (index, max. length, isFull?) and one ArrayList to receive both the integers above and the plays of each players (e.g., 1's and 0's standing for X's and O's). This is probably going to be split between 2 classes but the question remains the same. My current attempt looks like this: import java.util.ArrayList; public class Conn4Col { public int hMax; public int index; public final int initialSize = 0; public final int fullCol = 0; public ArrayList<Integer>; (...)} Unfortunately, this doesn't compile. The compiler says an is missing where my ArrayList declaration stands. We're just starting objects and we haven't really looked into other instance variables than the basic types. Can someone tell me where my error is and how to correct it? Many thanks, JDelage

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  • Manditory read-only fields in django

    - by jamida
    I'm writing a test "grade book" application. The models.py file is shown below. class Student(models.Model): name = models.CharField(max_length=50) parent = models.CharField(max_length=50) def __unicode__(self): return self.name class Grade(models.Model): studentId = models.ForeignKey(Student) finalGrade = models.CharField(max_length=3) I'd like to be able to change the final grade for several students in a modelformset but for now I'm just trying one student at a time. I'm also trying to create a form for it that shows the student name as a field that can not be changed, the only thing that can be changed here is the finalGrade. So I used this trick to make the studentId read-only. class GradeROForm(ModelForm): studentId = forms.ModelChoiceField(queryset=Student.objects.all()) def __init__(self, *args, **kwargs): super(GradeROForm,self).__init__(*args, **kwargs) instance = getattr(self, 'instance', None) if instance and instance.id: self.fields['studentId'].widget.attrs['disabled']='disabled' def clean_studentId(self): instance = getattr(self,'instance',None) if instance: return instance.studentId else: return self.cleaned_data.get('studentId',None) class Meta: model=Grade And here is my view: def modifyGrade(request,student): student = Student.objects.get(name=student) mygrade = Grade.objects.get(studentId=student) if request.method == "POST": myform = GradeROForm(data=request.POST, instance=mygrade) if myform.is_valid(): grade = myform.save() info = "successfully updated %s" % grade.studentId else: myform=GradeROForm(instance=mygrade) return render_to_response('grades/modifyGrade.html',locals()) This displays the form like I expect, but when I hit "submit" I get a form validation error for the student field telling me this field is required. I'm guessing that, since the field is "disabled", the value is not being reported in the POST and for reasons unknown to me the instance isn't being used in its place. I'm a new Django/Python programmer, but quite experienced in other languages. I can't believe I've stumbled upon such a difficult to solve problem in my first significant django app. I figure I must be missing something. Any ideas?

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  • nginx - Redirect specific page paths to https while keeping everything else on http (in a single server call)?

    - by Kris Anderson
    From what I've gathered so far it's clear that running if statements in nginx should be avoided at all costs. Most of the examples I've found so far regarding specific page redirects involve multiple servers being used. But, isn't that a bit wasteful? I'm not sure, but I would think multiple servers to accomplish this would be somewhat slower then a single server when under heavy load. My current server call is this: server { listen 10.0.0.60:80; listen 10.0.0.60:443 default ssl; #other code } What I want to do is redirect certain http requests to https requests. For example, I want /login/ and /my-account/ to always be forced to use SSL. If you're on /help/ though, I want that served over the default http. Is there a way to accomplish this within a single server call? Or is there no downside to using 2 server calls to get this working? nginx seems to be under pretty active development and a lot of the older guides I've followed were from times when you couldn't listen to requests for port 80 and 443 within the same server call. But now that nginx has been updated to support that (I'm running 1.2.4), I'm wondering if there's a "best practice" way of handling this today. Any help would be greatly appreciated. EDIT: I did find this guide: http://redant.com.au/blog/manage-ssl-redirection-in-nginx-using-maps-and-save-the-universe/ and I updated my code as follows: map $uri $my_preferred_proto { default "http"; ~^/#/user/login "https"; } server { listen 10.0.0.60:80; ## listen for ipv4; this line is default and implied listen 10.0.0.60:443 default ssl; if ($my_preferred_proto = "none") { set $my_preferred_proto $scheme; } if ($my_preferred_proto != $scheme) { return 301 $my_preferred_proto://mysite.com$request_uri; } It's not working though. When I change the default to https everything is redirected to SSL so it does somewhat work. But the redirect of /#/user/login is not redirecting to HTTPS. Any ideas? Also, is this a good way to go about this?

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  • Bundle a Python app as a single file to support add-ons or extensions?

    - by Brandon Craig Rhodes
    There are several utilities — all with different procedures, limitations, and target operating systems — for getting a Python package and all of its dependencies and turning them into a single binary program that is easy to ship to customers: http://wiki.python.org/moin/Freeze http://www.pyinstaller.org/ http://www.py2exe.org/ http://svn.pythonmac.org/py2app/py2app/trunk/doc/index.html My situation goes one step further: third-party developers will be wanting to write plug-ins, extensions, or add-ons for my application. It is, of course, a daunting question how users on platforms like Windows would most easily install plugins or addons in such a way that my app can easily discover that they have been installed. But beyond that basic question is another: how can a third-party developer bundle their extension with whatever libraries the extension itself needs (which might be binary modules, like lxml) in such a way that the plugin's dependencies become available for import at the same time that the plugin becomes available. How can this be approached? Will my application need its own plug-in area on disk and its own plug-in registry to make this tractable? Or are there general mechanisms, that I could avoid writing myself, that would allow an app that is distributed as a single executable to look around and find plugins that are also installed as single files?

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  • GAE - Getting TypeError requiring class instance be passed to class's own method...

    - by Spencer Leland
    I'm really new to programming... I set up a class to give supporting information for Google's User API user object. I store this info in the datastore using db.model. When I call the okstatus method of my user_info class using this code: elif user_info.okstatus(user): self.response.out.write("user allowed") I get this error: unbound method okstatus() must be called with user_info instance as first argument (got User instance instead) Here is my user_info class. class user_info: def auth_ctrlr(self, user): if self.status(user) == status_allowed: return ("<a href=\"%s\">Sign Out</a>)" % (users.create_login_url("/"))) else: return ("<a href=\"%s\">Sign In or Get an Account</a>)" % (users.create_logout_url("/"))) def status(self, user): match = sub_user.gql(qu_by_user_id, user.user_id) return match.string_status def group(self, user): match = sub_user.gql(qu_by_user_id, user.user_id) grp = group_names.gql(qu_by_user_id, match.groupID) return grp def okstatus(self, user): match = self.status(user) if match == status_allowed: return True My understanding is that the argument "self" inside the method's calling arguments describes it as a child to the class. I've tried everything I can think of and can't find any related info online. Can someone please tell me what I'm doing wrong? Thanks

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  • Is it possible that a single-threaded program is executed simultaneously on more than one CPU core?

    - by Wolfgang Plaschg
    When I run a single-threaded program that i have written on my quad core Intel i can see in the Windows Task Manager that actually all four cores of my CPU are more or less active. One core is more active than the other three, but there is also activity on those. There's no other program (besided the OS kernel of course) running that would be plausible for that activitiy. And when I close my program all activity an all cores drops down to nearly zero. All is left is a little "noise" on the cores, so I'm pretty sure all the visible activity comes directly or indirectly (like invoking system routines) from my program. Is it possible that the OS or the cores themselves try to balance some code or execution on all four cores, even it's not a multithreaded program? Do you have any links that documents this technique? Some infos to the program: It's a console app written in Qt, the Task Manager states that only one thread is running. Maybe Qt uses threads, but I don't use signals or slots, nor any GUI. Link to Task Manager screenshot: http://img97.imageshack.us/img97/6403/taskmanager.png This question is language agnostic and not tied to Qt/C++, i just want to know if Windows or Intel do to balance also single-threaded code on all cores. If they do, how does this technique work? All I can think of is, that kernel routines like reading from disk etc. is scheduled on all cores, but this won't improve performance significantly since the code still has to run synchronous to the kernel api calls. EDIT Do you know any tools to do a better analysis of single and/or multi-threaded programs than the poor Windows Task Manager?

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  • C#/.Net Error: MySql.Data Object reference not set to an instance of an object.

    - by Simon
    Hello, I get this exception on my Windows 7 64bit in application running in VS 2008 express. I am using Connector/Net 6.2.2.0: Message: Object reference not set to an instance of an object. Source: MySql.Data in MySql.Data.MySqlClient.NativeDriver.GetResult(Int32& affectedRow, Int32& insertedId) Stack trace: in MySql.Data.MySqlClient.Driver.GetResult(Int32 statementId, Int32& affectedRows, Int32& insertedId) in MySql.Data.MySqlClient.Driver.NextResult(Int32 statementId) in MySql.Data.MySqlClient.MySqlDataReader.NextResult() in MySql.Data.MySqlClient.MySqlDataReader.Close() in MySql.Data.MySqlClient.MySqlConnection.Close() in MySql.Data.MySqlClient.MySqlConnection.Dispose(Boolean disposing) in System.ComponentModel.Component.Finalize() No inner exception. This exception is unhalted and the debugger dont point on any code line. It just say "Object reference not set to an instance of an object. MySql.Data" This error is really hard to repeat. On my Windows XP 32bit is all ok. Could it be error in 64bit Windows 7? Thank you very much for your answers. Regards, simon

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  • How can I choose different hints for different joins for a single table in a query hint?

    - by RenderIn
    Suppose I have the following query: select * from A, B, C, D where A.x = B.x and B.y = C.y and A.z = D.z I have indexes on A.x and B.x and B.y and C.y and D.z There is no index on A.z. How can I give a hint to this query to use an INDEX hint on A.x but a USE_HASH hint on A.z? It seems like hints only take the table name, not the specific join, so when using a single table with multiple joins I can only specify a single strategy for all of them. Alternative, suppose I'm using a LEADING or ORDERED hint on the above query. Both of these hints only take a table name as well, so how can I ensure that the A.x = B.x join takes place before the A.z = D.z one? I realize in this case I could list D first, but imagine D subsequently joins to E and that the D-E join is the last one I want in the entire query. A third configuration -- Suppose I want the A.x join to be the first of the entire query, and I want the A.z join to be the last one. How can I use a hint to have a single join from A to take place, followed by the B-C join, and the A-D join last?

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  • In .NET, Why Can I Access Private Members of a Class Instance within the Class?

    - by AMissico
    While cleaning some code today written by someone else, I changed the access modifier from Public to Private on a class variable/member/field. I expected a long list of compiler errors that I use to "refactor/rework/review" the code that used this variable. Imagine my surprise when I didn't get any errors. After reviewing, it turns out that another instance of the Class can access the private members of another instance declared within the Class. Totally unexcepted. Is this normal? I been coding in .NET since the beginning and never ran into this issue, nor read about it. I may have stumbled onto it before, but only "vaguely noticed" and move on. Can anyone explain this behavoir to me? I would like to know the "why" I can do this. Please explain, don't just tell me the rule. Am I doing something wrong? I found this behavior in both C# and VB.NET. The code seems to take advantage of the ability to access private variables. Sincerely, Totally Confused Class Jack Private _int As Integer End Class Class Foo Public Property Value() As Integer Get Return _int End Get Set(ByVal value As Integer) _int = value * 2 End Set End Property Private _int As Integer Private _foo As Foo Private _jack As Jack Private _fred As Fred Public Sub SetPrivate() _foo = New Foo _foo.Value = 4 'what you would expect to do because _int is private _foo._int = 3 'TOTALLY UNEXPECTED _jack = New Jack '_jack._int = 3 'expected compile error _fred = New Fred '_fred._int = 3 'expected compile error End Sub Private Class Fred Private _int As Integer End Class End Class

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  • Single Responsibility Principle usage how can i call sub method correctly?

    - by Phsika
    i try to learn SOLID prencibles. i writed two type of code style. which one is : 1)Single Responsibility Principle_2.cs : if you look main program all instance generated from interface 1)Single Responsibility Principle_3.cs : if you look main program all instance genareted from normal class My question: which one is correct usage? which one can i prefer? namespace Single_Responsibility_Principle_2 { class Program { static void Main(string[] args) { IReportManager raporcu = new ReportManager(); IReport wordraporu = new WordRaporu(); raporcu.RaporHazirla(wordraporu, "data"); Console.ReadKey(); } } interface IReportManager { void RaporHazirla(IReport rapor, string bilgi); } class ReportManager : IReportManager { public void RaporHazirla(IReport rapor, string bilgi) { rapor.RaporYarat(bilgi); } } interface IReport { void RaporYarat(string bilgi); } class WordRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Word Raporu yaratildi:{0}",bilgi); } } class ExcellRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Excell raporu yaratildi:{0}",bilgi); } } class PdfRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("pdf raporu yaratildi:{0}",bilgi); } } } Second 0ne all instance genareted from normal class namespace Single_Responsibility_Principle_3 { class Program { static void Main(string[] args) { WordRaporu word = new WordRaporu(); ReportManager manager = new ReportManager(); manager.RaporHazirla(word,"test"); } } interface IReportManager { void RaporHazirla(IReport rapor, string bilgi); } class ReportManager : IReportManager { public void RaporHazirla(IReport rapor, string bilgi) { rapor.RaporYarat(bilgi); } } interface IReport { void RaporYarat(string bilgi); } class WordRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Word Raporu yaratildi:{0}",bilgi); } } class ExcellRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Excell raporu yaratildi:{0}",bilgi); } } class PdfRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("pdf raporu yaratildi:{0}",bilgi); } } }

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  • How to run multiple Linux installations on a single VirtualBox?

    - by NoCatharsis
    I just started playing with VirtualBox to check out different versions of Linux. I was wondering if it would be possible (and recommended) to set up a single virtual machine with multiple partitions - one for each separate version of Linux, one for swap memory, and one fully shared /home partition? Still new to Linux, but I've read this is a good way to partition so you can share common applications between Linux installations, however I think everything I've read is pertaining to literal partitions and not virtual machines.

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  • Can I run a site search like Lucene on a single 2 gig server that's also a web & mysql server

    - by ian.evans
    My site's pages have exceeded the limit of pages for Google Custom Search so many of the results are not found in our site search. I've been reading about Lucene, Nutch, Solr, etc and I'm wondering if I'd have the requirements for running those on a single server that also runs the site (on nginx) and our mysql server. We hae 2 gigs of RAM. I'd appreciate any suggestions for migrating to a new site search.

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  • On a linux server how do you use multiple terminals over a single ssh connection?

    - by epochwolf
    I often find myself opening several ssh connections in order to view several log files at a time with tail -f. This isn't a problem when I'm at home because I use public key encryption for password-less login. However, I will often use computer at my university to do this so I don't have the option of using my private key. It gets annoying to enter my password 4 or 5 times to get several terminal windows. How can I get multiple terminals over a single connection?

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  • Analyze log files from many languages using a single tool. And recommendations of logging frameworks

    - by Binary255
    We have a system build on lots of languages. The ones we are interested in logging, in order of priority, are: C/C++ PHP C# Bash Java Wish list: If it is possible, we would like logging to be achieved from the above languages in such a way that we may use a single log viewing tool for all of them. Ideally they would be in the same format, but next to that in as few formats as possible and readable from as many log file viewers as possible. If it is possible logging to a single log file or a set of log files would be nice. With a possibility to filter based on the source language that is being logged. We would like to copy the log files (or should be log to a database and copy it instead?) from multiple servers to a single location. So that we can analyze the log files from many servers at the same time (to see if any of our servers execute a certain piece legacy code for example). Being able to change logging level at runtime would be nice. Thank you for reading! It's quite a complex problem, I hope someone has wrestled with it before and has some valuable information!

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