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• Developing Mobile Applications: Web, Native, or Hybrid?

  - by Michelle Kimihira

  Authors: Joe Huang, Senior Principal Product Manager, Oracle Mobile Application Development Framework  and Carlos Chang, Senior Principal Product Director The proliferation of mobile devices and platforms represents a game-changing technology shift on a number of levels. Companies must decide not only the best strategic use of mobile platforms, but also how to most efficiently implement them. Inevitably, this conversation devolves to the developers, who face the task of developing and supporting mobile applications—not a simple task in light of the number of devices and platforms. Essentially, developers can choose from the following three different application approaches, each with its own set of pros and cons. Native Applications: This refers to apps built for and installed on a specific platform, such as iOS or Android, using a platform-specific software development kit (SDK).  For example, apps for Apple’s iPhone and iPad are designed to run specifically on iOS and are written in Xcode/Objective-C. Android has its own variation of Java, Windows uses C#, and so on.  Native apps written for one platform cannot be deployed on another. Native apps offer fast performance and access to native-device services but require additional resources to develop and maintain each platform, which can be expensive and time consuming. Mobile Web Applications: Unlike native apps, mobile web apps are not installed on the device; rather, they are accessed via a Web browser.  These are server-side applications that render HTML, typically adjusting the design depending on the type of device making the request.  There are no program coding constraints for writing server-side apps—they can be written in Java, C, PHP, etc., it doesn’t matter.  Instead, the server detects what type of mobile browser is pinging the server and adjusts accordingly. For example, it can deliver fully JavaScript and CSS-enabled content to smartphone browsers, while downgrading gracefully to basic HTML for feature phone browsers. Mobile apps work across platforms, but are limited to what you can do through a browser and require Internet connectivity. For certain types of applications, these constraints may not be an issue. Oracle supports mobile web applications via ADF Faces (for tablets) and ADF Mobile browser (Trinidad) for smartphone and feature phones. Hybrid Applications: As the name implies, hybrid apps combine technologies from native and mobile Web apps to gain the benefits each. For example, these apps are installed on a device, like their pure native app counterparts, while the user interface (UI) is based on HTML5.  This UI runs locally within the native container, which usually leverages the device’s browser engine.  The advantage of using HTML5 is a consistent, cross-platform UI that works well on most devices.  Combining this with the native container, which is installed on-device, provides mobile users with access to local device services, such as camera, GPS, and local device storage.  Native apps may offer greater flexibility in integrating with device native services.  However, since hybrid applications already provide device integrations that typical enterprise applications need, this is typically less of an issue.  The new Oracle ADF Mobile release is an HTML5 and Java hybrid framework that targets mobile app development to iOS and Android from one code base. So, Which is the Best Approach? The short answer is – the best choice depends on the type of application you are developing.  For instance, animation-intensive apps such as games would favor native apps, while hybrid applications may be better suited for enterprise mobile apps because they provide multi-platform support. Just for starters, the following issues must be considered when choosing a development path. Application Complexity: How complex is the application? A quick app that accesses a database or Web service for some data to display?  You can keep it simple, and a mobile Web app may suffice. However, for a mobile/field worker type of applications that supports mission critical functionality, hybrid or native applications are typically needed. Richness of User Interactivity: What type of user experience is required for the application?  Mobile browser-based app that’s optimized for mobile UI may suffice for quick lookup or productivity type of applications.  However, hybrid/native application would typically be required to deliver highly interactive user experiences needed for field-worker type of applications.  For example, interactive BI charts/graphs, maps, voice/email integration, etc.  In the most extreme case like gaming applications, native applications may be necessary to deliver the highly animated and graphically intensive user experience. Performance: What type of performance is required by the application functionality?  For instance, for real-time look up of data over the network, mobile app performance depends on network latency and server infrastructure capabilities.  If consistent performance is required, data would typically need to be cached, which is supported on hybrid or native applications only. Connectivity and Availability: What sort of connectivity will your application require? Does the app require Web access all the time in order to always retrieve the latest data from the server? Or do the requirements dictate offline support? While native and hybrid apps can be built to operate offline, Web mobile apps require Web connectivity. Multi-platform Requirements: The terms “consumerization of IT” and BYOD (bring your own device) effectively mean that the line between the consumer and the enterprise devices have become blurred. Employees are bringing their personal mobile devices to work and are often expecting that they work in the corporate network and access back-office applications.  Even if companies restrict access to the big dogs: (iPad, iPhone, Android phones and tablets, possibly Windows Phone and tablets), trying to support each platform natively will require increasing resources and domain expertise with each new language/platform. And let’s not forget the maintenance costs, involved in upgrading new versions of each platform.   Where multi-platform support is needed, Web mobile or hybrid apps probably have the advantage. Going native, and trying to support multiple operating systems may be cost prohibitive with existing resources and developer skills. Device-Services Access:  If your app needs to access local device services, such as the camera, contacts app, accelerometer, etc., then your choices are limited to native or hybrid applications.   Fragmentation: Apple controls Apple iOS and the only concern is what version iOS is running on any given device.   Not so Android, which is open source. There are many, many versions and variants of Android running on different devices, which can be a nightmare for app developers trying to support different devices running different flavors of Android.  (Is it an Amazon Kindle Fire? a Samsung Galaxy?  A Barnes & Noble Nook?) This is a nightmare scenario for native apps—on the other hand, a mobile Web or hybrid app, when properly designed, can shield you from these complexities because they are based on common frameworks.  Resources: How many developers can you dedicate to building and supporting mobile application development?  What are their existing skills sets?  If you’re considering native application development due to the complexity of the application under development, factor the costs of becoming proficient on a each platform’s OS and programming language. Add another platform, and that’s another language, another SDK. On the other side of the equation, Web mobile or hybrid applications are simpler to make, and readily support more platforms, but there may be performance trade-offs. Conclusion This only scratches the surface. However, I hope to have suggested some food for thought in choosing your mobile development strategy.  Do your due diligence, search the Web, read up on mobile, talk to peers, attend events. The development team at Oracle is working hard on mobile technologies to help customers extend enterprise applications to mobile faster and effectively.  To learn more on what Oracle has to offer, check out the Oracle ADF Mobile (hybrid) and ADF Faces/ADF Mobile browser (Web Mobile) solutions from Oracle.   Additional Information Blog: ADF Blog Product Information on OTN: ADF Mobile Product Information on Oracle.com: Oracle Fusion Middleware Follow us on Twitter and Facebook Subscribe to our regular Fusion Middleware Newsletter

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• Expectations + Rewards = Innovation

  - by D'Arcy Lussier

  “Innovation” is a heavy word. We regard those that embrace it as “Innovators”. We describe organizations as being “Innovative”. We hold those associated with the word in high regard, even though its dictionary definition is very simple: Introducing something new. What our culture has done is wrapped Innovation in white robes and a gold crown. Innovation is rarely just introducing something new. Innovations and innovators are typically associated with other terms: groundbreaking, genius, industry-changing, creative, leading. Being a true innovator and creating innovations are a big deal, and something companies try to strive for…or at least say they strive for. There’s huge value in being recognized as an innovator in an industry, since the idea is that innovation equates to increased profitability. IBM ran an ad a few years back that showed what their view of innovation is: “The point of innovation is to make actual money.” If the money aspect makes you feel uneasy, consider it another way: the point of innovation is to <insert payoff here>. Companies that innovate will be more successful. Non-profits that innovate can better serve their target clients. Governments that innovate can better provide services to their citizens. True innovation is not easy to come by though. As with anything in business, how well an organization will innovate is reliant on the employees it retains, the expectations placed on those employees, and the rewards available to them. In a previous blog post I talked about one formula: Right Employees + Happy Employees = Productive Employees I want to introduce a new one, that builds upon the previous one: Expectations + Rewards = Innovation  The level of innovation your organization will realize is directly associated with the expectations you place on your staff and the rewards you make available to them. Expectations We may feel uncomfortable with the idea of placing expectations on our staff, mainly because expectation has somewhat of a negative or cold connotation to it: “I expect you to act this way or else!” The problem is in the or-else part…we focus on the negative aspects of failing to meet expectations instead of looking at the positive side. “I expect you to act this way because it will produce <insert benefit here>”. Expectations should not be set to punish but instead be set to ensure quality. At a recent conference I spoke with some Microsoft employees who told me that you have five years from starting with the company to reach a “Senior” level. If you don’t, then you’re let go. The expectation Microsoft placed on their staff is that they should be working towards improving themselves, taking more responsibility, and thus ensure that there is a constant level of quality in the workforce. Rewards Let me be clear: a paycheck is not a reward. A paycheck is simply the employer’s responsibility in the employee/employer relationship. A paycheck will never be the key motivator to drive innovation. Offering employees something over and above their required compensation can spur them to greater performance and achievement. Working in the food service industry, this tactic was used again and again: whoever has the highest sales over lunch will receive a free lunch/gift certificate/entry into a draw/etc. There was something to strive for, to try beyond the baseline of what our serving jobs were. It was through this that innovative sales techniques would be tried and honed, with key servers being top sellers time and time again. At a code camp I spoke at, I was amazed to see that all the employees from one company receive $100 Visa gift cards as a thank you for taking time to speak. Again, offering something over and above that can give that extra push for employees. Rewards work. But what about the fairness angle? In the restaurant example I gave, there were servers that would never win the competition. They just weren’t good enough at selling and never seemed to get better. So should those that did work at performing better and produce more sales for the restaurant not get rewarded because those who weren’t working at performing better might get upset? Of course not! Organizations succeed because of their top performers and those that strive to join their ranks. The Expectation/Reward Graph While the Expectations + Rewards = Innovation formula may seem like a simple mathematics formula, there’s much more going under the hood. In fact there are three different outcomes that could occur based on what you put in as values for Expectations and Rewards. Consider the graph below and the descriptions that follow: Disgruntled – High Expectation, Low Reward I worked at a company where the mantra was “Company First, Because We Pay You”. Even today I still hear stories of how this sentiment continues to be perpetuated: They provide you a paycheck and a means to live, therefore you should always put them as your top priority. Of course, this is a huge imbalance in the expectation/reward equation. Why would anyone willingly meet high expectations of availability, workload, deadlines, etc. when there is no reward other than a paycheck to show for it? Remember: paychecks are not rewards! Instead, you see employees be disgruntled which not only affects the level of production but also the level of quality within an organization. It also means that you see higher turnover. Complacent – Low Expectation, Low Reward Complacency is a systemic problem that typically exists throughout all levels of an organization. With no real expectations or rewards, nobody needs to excel. In fact, those that do try to innovate, improve, or introduce new things into the organization might be shunned or pushed out by the rest of the staff who are just doing things the same way they’ve always done it. The bigger issue for the organization with low/low values is that at best they’ll never grow beyond their current size (and may shrink actually), and at worst will cease to exist. Entitled – Low Expectation, High Reward It’s one thing to say you have the best people and reward them as such, but its another thing to actually have the best people and reward them as such. Organizations with Entitled employees are the former: their organization provides them with all types of comforts, benefits, and perks. But there’s no requirement before the rewards are dolled out, and there’s no short-list of who receives the rewards. Everyone in the company is treated the same and is given equal share of the spoils. Entitlement is actually almost identical with Complacency with one notable difference: just try to introduce higher expectations into an entitled organization! Entitled employees have been spoiled for so long that they can’t fathom having rewards taken from them, or having to achieve specific levels of performance before attaining them. Those running the organization also buy in to the Entitled sentiment, feeling that they must persist the same level of comforts to appease their staff…even though the quality of the employee pool may be suspect. Innovative – High Expectation, High Reward Finally we have the Innovative organization which places high expectations but also provides high rewards. This organization gets it: if you truly want the best employees you need to apply equal doses of pressure and praise. Realize that I’m not suggesting crazy overtime or un-realistic working conditions. I do not agree with the “Glengary-Glenross” method of encouragement. But as anyone who follows sports can tell you, the teams that win are the ones where the coaches push their players to be their best; to achieve new levels of performance that they didn’t know they could receive. And the result for the players is more money, fame, and opportunity. It’s in this environment that organizations can focus on innovation – true innovation that builds the business and allows everyone involved to truly benefit. In Closing Organizations love to use the word “Innovation” and its derivatives, but very few actually do innovate. For many, the term has just become another marketing buzzword to lump in with all the other business terms that get overused. But for those organizations that truly get the value of innovation, they will be the ones surging forward while other companies simply fade into the background. And they will be the organizations that expect more from their employees, and give them their just rewards.

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• Orchestrating the Virtual Enterprise

  - by John Murphy

  During the American Industrial Revolution, the Ford Motor Company did it all. It turned raw materials into a showroom full of Model Ts. It owned a steel mill, a glass factory, and an automobile assembly line. The company was both self-sufficient and innovative and went on to become one of the largest and most profitable companies in the world. Nowadays, it's unusual for any business to follow this vertical integration model because its much harder to be best in class across such a wide a range of capabilities and services. Instead, businesses focus on their core competencies and outsource other business functions to specialized suppliers. They exchange vertical integration for collaboration. When done well, all parties benefit from this arrangement and the collaboration leads to the creation of an agile, lean and successful "virtual enterprise." Case in point: For Sun hardware, Oracle outsources most of its manufacturing and all of its logistics to third parties. These are vital activities, but ones where Oracle doesn't have a core competency, so we shift them to business partners who do. Within our enterprise, we always retain the core functions of product development, support, and most of the sales function, because that's what constitutes our core value to our customers. This is a perfect example of a virtual enterprise.  What are the implications of this? It means that we must exchange direct internal control for indirect external collaboration. This fundamentally changes the relative importance of different business processes, the boundaries of security and information sharing, and the relationship of the supply chain systems to the ERP. The challenge is that the systems required to support this virtual paradigm are still mired in "island enterprise" thinking. But help is at hand. Developments such as the Web, social networks, collaboration, and rules-based orchestration offer great potential to fundamentally re-architect supply chain systems to better support the virtual enterprise.  Supply Chain Management Systems in a Virtual Enterprise Historically enterprise software was constructed to automate the ERP - and then the supply chain systems extended the ERP. They were joined at the hip. In virtual enterprises, the supply chain system needs to be ERP agnostic, sitting above each of the ERPs that are distributed across the virtual enterprise - most of which are operating in other businesses. This is vital so that the supply chain system can manage the flow of material and the related information through the multiple enterprises. It has to have strong collaboration tools. It needs to be highly flexible. Users need to be able to see information that's coming from multiple sources and be able to react and respond to events across those sources.  Oracle Fusion Distributed Order Orchestration (DOO) is a perfect example of a supply chain system designed to operate in this virtual way. DOO embraces the idea that a company's fulfillment challenge is a distributed, multi-enterprise problem. It enables users to manage the process and the trading partners in a uniform way and deliver a consistent user experience while operating over a heterogeneous, virtual enterprise. This is a fundamental shift at the core of managing supply chains. It forces virtual enterprises to think architecturally about how best to construct their supply chain systems.  Case in point, almost everyone has ordered from Amazon.com at one time or another. Our orders are as likely to be fulfilled by third parties as they are by Amazon itself. To deliver the order promptly and efficiently, Amazon has to send it to the right fulfillment location and know the availability in that location. It needs to be able to track status of the fulfillment and deal with exceptions. As a virtual enterprise, Amazon's operations, using thousands of trading partners, requires a very different approach to fulfillment than the traditional 'take an order and ship it from your own warehouse' model. Amazon had no choice but to develop a complex, expensive and custom solution to tackle this problem as there used to be no product solution available. Now, other companies who want to follow similar models have a better off-the-shelf choice -- Oracle Distributed Order Orchestration (DOO).  Consider how another of our customers is using our distributed orchestration solution. This major airplane manufacturer has a highly complex business and interacts regularly with the U.S. Government and major airlines. It sits in the middle of an intricate supply chain and needed to improve visibility across its many different entities. Oracle Fusion DOO gives the company an orchestration mechanism so it could improve quality, speed, flexibility, and consistency without requiring an organ transplant of these highly complex legacy systems. Many retailers face the challenge of dealing with brick and mortar, Web, and reseller channels. They all need to be knitted together into a virtual enterprise experience that is consistent for their customers. When a large U.K. grocer with a strong brick and mortar retail operation added an online business, they turned to Oracle Fusion DOO to bring these entities together. Disturbing the Peace with Acquisitions Quite often a company's ERP system is disrupted when it acquires a new company. An acquisition can inject a new set of processes and systems -- or even introduce an entirely new business like Sun's hardware did at Oracle. This challenge has been a driver for some of our DOO customers. A large power management company is using Oracle Fusion DOO to provide the flexibility to rapidly integrate additional products and services into its central fulfillment operation. The Flip Side of Fulfillment Meanwhile, we haven't ignored similar challenges on the supply side of the equation. Specifically, how to manage complex supply in a flexible way when there are multiple trading parties involved? How to manage the supply to suppliers? How to manage critical components that need to merge in a tier two or tier three supply chain? By investing in supply orchestration solutions for the virtual enterprise, we plan to give users better visibility into their network of suppliers to help them drive down costs. We also think this technology and full orchestration process can be applied to the financial side of organizations. An example is transactions that flow through complex internal structures to minimize tax exposure. We can help companies manage those transactions effectively by thinking about the internal organization as a virtual enterprise and bringing the same solution set to this internal challenge.  The Clear Front Runner No other company is investing in solving the virtual enterprise supply chain issues like Oracle is. Oracle is in a unique position to become the gold standard in this market space. We have the infrastructure of Oracle technology. We already have an Oracle Fusion DOO application which embraces the best of what's required in this area. And we're absolutely committed to extending our Fusion solution to other use cases and delivering even more business value.

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• SignalR Server Error "The ConnectionId is in the incorrect format." with SignalR-ObjC Library

  - by ozzotto

  Before asking a separate question I've done lots of googling about it and added a comment in the already existing stackoverflow question. I have a SignalR Hub (tried both v. 1.1.3 and 2.0.0-rc) in my server with the below code: [HubName("TestHub")] public class TestHub : Hub { [Authorize] public void TestMethod(string test) { //some stuff here Clients.Caller.NotifyOnTestCompleted(); } } The problem persists if I remove the Authorize attribute. And in my iOS client I try to call it with the below code: SRHubConnection *hubConnection = [SRHubConnection connectionWithURL:_baseURL]; SRHubProxy *hubProxy = [hubConnection createHubProxy:@"TestHub"]; [hubProxy on:@"NotifyOnTestCompleted" perform:self selector:@selector(stopConnection)]; hubConnection.started = ^{ [hubProxy invoke:@"TestMethod" withArgs:@[@"test"]]; }; //received, error handling [hubConnection start]; When the app starts the user is not logged in and there is no open SignalR connection. The users logs in by calling a Login service in the server which makes use of WebSecurity.Login method. If the login service returns success I then make the above call to SignalR Hub and I get the server error 500 with description "The ConnectionId is in the incorrect format.". The full server stacktrace is the following: Exception information: Exception type: InvalidOperationException Exception message: The ConnectionId is in the incorrect format. at Microsoft.AspNet.SignalR.PersistentConnection.GetConnectionId(HostContext context, String connectionToken) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.Hubs.HubDispatcher.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(IDictionary`2 environment) at Microsoft.Owin.Mapping.MapMiddleware.<Invoke>d__0.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork(IAsyncResult ar) at System.Web.HttpApplication.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Request information: Request URL: http://myserverip/signalr/signalr/connect?transport=webSockets&connectionToken=axJs EQMZxpmUopL36owSUkdhNs85E0fyB2XvV5R5znZfXYI/CiPbTRQ3kASc3 mq60cLkZU7coYo1P fbC0U1LR2rI6WIvCNIMOmv/mHut/Unt9mX3XFkQb053DmWgCan5zHA==&connectionData=[{"Name":"testhub"}] Request path: /signalr/signalr/connect User host address: User: Is authenticated: False Authentication Type: Thread account name: IIS APPPOOL\DefaultAppPool Thread information: Thread ID: 14 Thread account name: IIS APPPOOL\DefaultAppPool Is impersonating: True Stack trace: at Microsoft.AspNet.SignalR.PersistentConnection.GetConnectionId(HostContext context, String connectionToken) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.Hubs.HubDispatcher.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(IDictionary`2 environment) at Microsoft.Owin.Mapping.MapMiddleware.<Invoke>d__0.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork(IAsyncResult ar) at System.Web.HttpApplication.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) I understand this is some kind of authentication and user identity mismatching but up to now I have found no way of solving it. All other questions suggest stoping the opened connection when the user identity changes but as I mentioned above I have no open connection before the user logs in successfully. Any help would be much appreciated. Thank you.

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• Properly clean up excel interop objects revisited: Wrapper objects

  - by chiccodoro

  Hi all, Excel 2007 Hangs When Closing via .NET How to properly clean up Excel interop objects in C# How to properly clean up interop objects in C# All of these struggle with the problem that C# does not release the Excel COM objects properly after using them. There are mainly two directions of working around this issue: Kill the Excel process when Excel is not used anymore. Take care to assign each COM object used explicitly to a variable and to Marshal.ReleaseComObject all of these. Some have stated that 2 is too tedious and there is always some uncertainty whether you forget to stick to this rule at some places in the code. Still 1 seems dirty and dangerous to me, also I could imagine that in an environment with restricted access killing processes is not allowed. So I've been thinking about solving 2 by creating another proxy object model which mimics the Excel object model (for me, it would suffice to implement the objects I actually need). The principle would look as follows: Each Excel Interop class has its proxy which wraps an object of that class. The proxy releases the COM object in its destructor. The proxy mimics the interface of the Interop class (maybe by inheriting it). Any methods that usually return another COM object return a proxy instead. The other methods simply delegate the implementation to the inner COM object. This is a rough sketch of the code: public class Application : Microsoft.Office.Interop.Excel.Application { private Microsoft.Office.Interop.Excel.Application innerApplication = new Microsoft.Office.Interop.Excel.Application innerApplication(); ~Application() { Marshal.ReleaseCOMObject(innerApplication); } public Workbooks Workbooks { get { return new Workbooks(innerApplication.Workbooks); } } } public class Workbooks { private Microsoft.Office.Interop.Excel.Workbooks innerWorkbooks; Workbooks(Microsoft.Office.Interop.Excel.Workbooks innerWorkbooks) { this.innerWorkbooks = innerWorkbooks; } ~Workbooks() { Marshal.ReleaseCOMObject(innerWorkbooks); } } My questions to you are in particular: Who finds this a bad idea and why? Who finds this a gread idea? If so, why hasn't anybody implemented/published such a model yet? Just due to the effort, or am I missing a killing problem with that idea? Is it impossible/bad/dangerous to do the ReleaseCOMObject in the destructor? (I've only seen proposals to put it in a Dispose() rather than in a destructor - why?) If the approach makes sense, any suggestions to improve it?

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• Why is code quality not popular?

  - by Peter Kofler

  I like my code being in order, i.e. properly formatted, readable, designed, tested, checked for bugs, etc. In fact I am fanatic about it. (Maybe even more than fanatic...) But in my experience actions helping code quality are hardly implemented. (By code quality I mean the quality of the code you produce day to day. The whole topic of software quality with development processes and such is much broader and not the scope of this question.) Code quality does not seem popular. Some examples from my experience include Probably every Java developer knows JUnit, almost all languages implement xUnit frameworks, but in all companies I know, only very few proper unit tests existed (if at all). I know that it's not always possible to write unit tests due to technical limitations or pressing deadlines, but in the cases I saw, unit testing would have been an option. If a developer wanted to write some tests for his/her new code, he/she could do so. My conclusion is that developers do not want to write tests. Static code analysis is often played around in small projects, but not really used to enforce coding conventions or find possible errors in enterprise projects. Usually even compiler warnings like potential null pointer access are ignored. Conference speakers and magazines would talk a lot about EJB3.1, OSGI, Cloud and other new technologies, but hardly about new testing technologies or tools, new static code analysis approaches (e.g. SAT solving), development processes helping to maintain higher quality, how some nasty beast of legacy code was brought under test, ... (I did not attend many conferences and it propably looks different for conferences on agile topics, as unit testing and CI and such has a higer value there.) So why is code quality so unpopular/considered boring? EDIT: Thank your for your answers. Most of them concern unit testing (and has been discussed in a related question). But there are lots of other things that can be used to keep code quality high (see related question). Even if you are not able to use unit tests, you could use a daily build, add some static code analysis to your IDE or development process, try pair programming or enforce reviews of critical code.

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• Moose and error messages, the sun and the moon [closed]

  - by xxxxxxx

  So again using Moose I write a role like this: package My::Role; use Moose::Role; use Some::Class::Consuming::My::Role; With the note that Some::Class::Consuming::My::Role consumes the role My::Role; And what do I get ? I get an error message like this: A role generator is required to generate roles at /usr/local/share/perl/5.10.0/MooseX/Role/Parameterized/Meta/Role/Parameterizable.pm line 79 MooseX::Role::Parameterized::Meta::Role::Parameterizable::generate_role('MooseX::Role::Parameterized::Meta::Role::Parameterizable=HASH...', 'consumer', 'Moose::Meta::Class=HASH(0x894e540)', 'parameters', 'HASH(0x86fc1e0)') called at /usr/local/share/perl/5.10.0/MooseX/Role/Parameterized/Meta/Role/Parameterizable.pm line 116 MooseX::Role::Parameterized::Meta::Role::Parameterizable::apply('MooseX::Role::Parameterized::Meta::Role::Parameterizable=HASH...', 'Moose::Meta::Class=HASH(0x894e540)', 'element_type', 'Tuple') called at /usr/local/lib/perl/5.10.0/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0x894e540)', undef, 'Stuff', 'HASH(0x894e1d0)') called at /usr/local/lib/perl/5.10.0/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0x894e540)', 'Stuff', 'HASH(0x894e1d0)') called at /usr/local/lib/perl/5.10.0/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0x894e540)', 'Group', 'HASH(0x894e1d0)') called at /usr/local/lib/perl/5.10.0/Moose/Exporter.pm line 293 Moose::with('Group', 'HASH(0x894e1d0)') called at Some_path_on_disk line 6 require Some_other_path_on_disk called at Some_path_on_disk line 9 Group::BEGIN() called at Yet_another_path_on_disk line 0 eval {...} called at Yet_another_path_on_disk line 0 Compilation failed in require at some_path_on_disk line 9. BEGIN failed--compilation aborted at some_path_on_disk line 9. What am I to make of this ? As Dijkstra would concisely describe, this looks like "just a meaningless concatenation of words"(which is exactly what it is). Would a more appropriate error message be "You cannot use a class consuming the role that you are currently defining " ? What does the error message try to convey ? Can the author make the error message meaningful ? Will he ever make it so ? maybe this can be planned for version 3.14159265358979323846 ? In actuality I get one and a half pages of error which is completely unreadable and devoid of any logic or sense of respect for the user that is using Moose (in terms of intuitive error messages) just like the one above. What's to be done in this case ? I mean I get on my screen these error messages that are sometimes completely unrelated to the problem that I'm having (which I can assess after solving the problems that probably caused them, I say probably becuase I have no idea where these error messages came from because they look like they fell from the sky as they have no relation to the actual situation). Is this: the inexplicable dramatic destiny of the Perl programmer using Moose ? someone being extremely lazy and sloppy at writing error messages ? maybe on heavy drugs ? me not understanding basic english ? Gentlemen, when writing software, please please please, take care of the poor programmer that will use it and respect him by writing relevant error messages. (Except for error messages Moose is a pretty good piece of software)

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• WCF Timeout issue - should there even be a socket connection?

  - by stiank81

  I have a .Net application which is split into a client and server side. The communication between them is handled using WCF. I'm not using the automagic service references, but instead I've built the connection manually like described in the Screencast by Miguel Castro. Summarized this means that I create a console application on the server side that holds ServiceHost objects for the different services: var myServiceHost = new System.ServiceModel.ServiceHost(typeof(MyService), new Uri("net.tcp://localhost:8002")); myServiceHost.Open(); And on the client side I have service proxies creating channels using the ChannelFactory: IMyService proxy = new ChannelFactory<IMyService>("MyServiceEndpoint").CreateChannel(); The client and server side share the service contract defined in the interface IMyService. And another advantage is that I get minimal App.config files - without all the autogenerated stuff created through the Service References. Example from client side: <?xml version="1.0"?> <configuration> <system.serviceModel> <client> <endpoint address="net.tcp://localhost:8002/MyEndpoint" binding="netTcpBinding" contract="IMyService" name="MyServiceEndpoint"/> </client> </system.serviceModel> </configuration> So - to my problem. I create the proxy once, and it holds a channel all the way through the application. However, if I leave the application without use for a few minutes the channel has timed out, and I get the following exception: The socket connection was aborted. This could be caused by an error processing your message or a receive timeout being exceeded by the remote host, or an underlying network resource issue. Local socket timeout was '00:00:59.9979998'. How do I prevent this? I'm assuming I need to specify a higher timeout in my configuration? But I don't want it to ever time out. But on the other hand - I don't want a socket connection! Do I need one? Thought I could go connection less with WCF... What's the permanent solution and best practice on solving this? Set timeout to "never".. Create a new channel for each request? I'm assuming there is some overhead creating the channel?.. Increase the timeout to e.g. 5minutes and create new channel if the connection did timeout? Make it connection less somehow? (Without the overhead of creating channels..) Something else...

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• get local groups and not the primary groups for a domain user

  - by user175084

  i have a code to get the groups a user belongs to. try { DirectoryEntry adRoot = new DirectoryEntry(string.Format("WinNT://{0}", Environment.UserDomainName)); DirectoryEntry user = adRoot.Children.Find(completeUserName, "User"); object obGroups = user.Invoke("Groups"); foreach (object ob in (IEnumerable)obGroups) { // Create object for each group. DirectoryEntry obGpEntry = new DirectoryEntry(ob); listOfMyWindowsGroups.Add(obGpEntry.Name); } return true; } catch (Exception ex) { new GUIUtility().LogMessageToFile("Error in getting User MachineGroups = " + ex); return false; } the above code works fine when i have to find the groups of a local user but for a domain user it returns a value "Domain User" which is kind of wierd as it is a part of 2 local groups. Please can some1 help in solving this mystery. thanks Research I did some finding and got that i am being returned the primary group of the domain user called "Domain User" group but what i actually want is the groups of the local machines the domain user is a part of... i cannot get that.. any suggestions another code using LDAP string domain = Environment.UserDomainName; DirectoryEntry DE = new DirectoryEntry("LDAP://" + domain, null, null, AuthenticationTypes.Secure); DirectorySearcher search = new DirectorySearcher(); search.SearchRoot = DE; search.Filter = "(SAMAccountName=" + completeUserName + ")"; //Searches active directory for the login name search.PropertiesToLoad.Add("displayName"); // Once found, get a list of Groups try { SearchResult result = search.FindOne(); // Grab the records and assign them to result if (result != null) { DirectoryEntry theUser = result.GetDirectoryEntry(); theUser.RefreshCache(new string[] { "tokenGroups" }); foreach (byte[] resultBytes in theUser.Properties["tokenGroups"]) { System.Security.Principal.SecurityIdentifier mySID = new System.Security.Principal.SecurityIdentifier(resultBytes, 0); DirectorySearcher sidSearcher = new DirectorySearcher(); sidSearcher.SearchRoot = DE; sidSearcher.Filter = "(objectSid=" + mySID.Value + ")"; sidSearcher.PropertiesToLoad.Add("distinguishedName"); SearchResult sidResult = sidSearcher.FindOne(); if (sidResult != null) { listOfMyWindowsGroups.Add((string)sidResult.Properties["distinguishedName"][0]); } } } else { new GUIUtility().LogMessageToFile("no user found"); } return true; } catch (Exception ex) { new GUIUtility().LogMessageToFile("Error obtaining group names: " + ex.Message + " Please contact your administrator."); // If an error occurs report it to the user. return false; } this works too but i get the same result "Domain Users" . Please can some1 tell me how to get the local machine groups...????

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• Get the string representation of a jquery DOM object's entire HTML

  - by Scozzard

  Hi, I have had a bit of a look around and am having some difficulty solving a wee issue I am having. I basically have a string of HTML, I convert that to a JQuery DOM object so that I can easily remove all elements that have a certain class using JQuery's .remove(). I.e., var radHtml = editor.get_html(); var jqDom = $(radHtml); $(".thickbox", jqDom).remove(); $(".thickboxcontent", jqDom).remove(); editor.set_html(this.innerHTML); NOTE: The HTML is derived from content in a RADEditor text editor so there are no parent HTML tags, so can look as follows: <p>This is a header</p> <p>this is some content followed by a table </p> <a href="#TB_inline?height=350&amp;width=400&amp;inlineId=myOnPageContent0" class="thickbox">Test Thickbox</a> <div id="myOnPageContent0" class="thickboxcontent"> <table class="modal"> <thead> </thead> <tbody> <tr> <td>item</td> <td>result</td> </tr> <tr> <td>item 1</td> <td>1</td> </tr> <tr> <td>item 2</td> <td>2</td> </tr> <tr> <td>item 3</td> <td>3</td> </tr> </tbody> </table> </div> Here is what the jqDom.html() returns from the HTML above: "This is a header" I was wondering if there was an easy way to do this - have some html and remove all elements (in this case divs) that have a certain class (but leaving their contents). JQuery doesnt have to used, but I would like to. Manipulating the DOM object is fine - it is getting the full DOM object in its entirety as a string that I am having the problem with. Any help would be much appreicated. Thanks.

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• Filtering a collection based on filtering rules

  - by Mike

  I have an observable collection of Entities, with each entity having a status added, deleted, modified and cancelled. I have four buttons (toggle) when clicked should filter my collection as below: If I select the button Added, then my collection should contain entities with status added. If I select the button Deleted and Added, then my collection should contain entities with status Deleted AND entities with status Added, none of the rest. If I select the button Deleted,Added and Modified, then my collection should contain entities with status Deleted, Added AND Modified. . . so on. If I unselect one of the buttons, it should remove those entities from the collection with that status. For example if I unselect Deleted, but select Added and Modified, then my collection should contain items with Added and Modified status and NOT Deleted ones. For implementing this I have created a master collection and a filtered collection. The Filter collection gets filtered based on the selections and unselections. The following is my code: private bool _clickedAdded; public bool ClickedAdded { get { return _clickedAdded; } set { _clickedAdded = value; if(!_clickedAdded) FilterAny(typeof(Added)); } } private bool _clickedDeleted; public bool ClickedDeleted { get { return _clickedDeleted; } set { _clickedDeleted = value; if (!_clickedDeleted) FilterAny(typeof(Deleted)); } } private bool _clickedModified; public bool ClickedModified { get { return _clickedModified; } set { _clickedModified = value; if (!_clickedModified) FilterAny(typeof(Modified)); } } private void FilterAny(Type status) { Func<Entity, bool> predicate = entity => entity.Status.GetType() != status; var filteredItems = MasterEntites.Where(predicate); FilteredEntities = new ObservableCollection<Entity>(filteredItems); } This however breaks the above rules - for example if I have all selected, and then I remove Added followed by deleted then it still shows the list of Added, Modified and Cancelled. It should be just Modified and Cancelled in the filtered collection. Can you please help me in solving this issue? Also do I need 2 different list to solve this. Please note that I'm using .NET 3.5.

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• Asynchronous subprocess on Windows

  - by Stigma

  First of all, the overall problem I am solving is a bit more complicated than I am showing here, so please do not tell me 'use threads with blocking' as it would not solve my actual situation without a fair, FAIR bit of rewriting and refactoring. I have several applications which are not mine to modify, which take data from stdin and poop it out on stdout after doing their magic. My task is to chain several of these programs. Problem is, sometimes they choke, and as such I need to track their progress which is outputted on STDERR. pA = subprocess.Popen(CommandA, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE) # ... some more processes make up the chain, but that is irrelevant to the problem pB = subprocess.Popen(CommandB, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=pA.stdout ) Now, reading directly through pA.stdout.readline() and pB.stdout.readline(), or the plain read() functions, is a blocking matter. Since different applications output in different paces and different formats, blocking is not an option. (And as I wrote above, threading is not an option unless at a last, last resort.) pA.communicate() is deadlock safe, but since I need the information live, that is not an option either. Thus google brought me to this asynchronous subprocess snippet on ActiveState. All good at first, until I implement it. Comparing the cmd.exe output of pA.exe | pB.exe, ignoring the fact both output to the same window making for a mess, I see very instantaneous updates. However, I implement the same thing using the above snippet and the read_some() function declared there, and it takes over 10 seconds to notify updates of a single pipe. But when it does, it has updates leading all the way upto 40% progress, for example. Thus I do some more research, and see numerous subjects concerning PeekNamedPipe, anonymous handles, and returning 0 bytes available even though there is information available in the pipe. As the subject has proven quite a bit beyond my expertise to fix or code around, I come to Stack Overflow to look for guidance. :) My platform is W7 64-bit with Python 2.6, the applications are 32-bit in case it matters, and compatibility with Unix is not a concern. I can even deal with a full ctypes or pywin32 solution that subverts subprocess entirely if it is the only solution, as long as I can read from every stderr pipe asynchronously with immediate performance and no deadlocks. :)

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• Merging two XML files into one XML file using Java

  - by dmurali

  I am stuck with how to proceed with combining two different XML files(which has the same structure). When I was doing some research on it, people say that XML parsers like DOM or StAX will have to be used. But cant I do it with the regular IOStream? I am currently trying to do with the help of IOStream but this is not solving my purpose, its being more complex. For example, What I have tried is; public class GUI { public static void main(String[] args) throws Exception { // Creates file to write to Writer output = null; output = new BufferedWriter(new FileWriter("C:\\merged.xml")); String newline = System.getProperty("line.separator"); output.write(""); // Read in xml file 1 FileInputStream in = new FileInputStream("C:\\1.xml"); BufferedReader br = new BufferedReader(new InputStreamReader(in)); String strLine; while ((strLine = br.readLine()) != null) { if (strLine.contains("<MemoryDump>")){ strLine = strLine.replace("<MemoryDump>", "xmlns:xsi"); } if (strLine.contains("</MemoryDump>")){ strLine = strLine.replace("</MemoryDump>", "xmlns:xsd"); } output.write(newline); output.write(strLine); System.out.println(strLine); } // Read in xml file 2 FileInputStream in = new FileInputStream("C:\\2.xml"); BufferedReader br1 = new BufferedReader(new InputStreamReader(in)); String strLine1; while ((strLine1 = br1.readLine()) != null) { if (strLine1.contains("<MemoryDump>")){ strLine1 = strLine1.replace("<MemoryDump>", ""); } if (strLine1.contains("</MemoryDump>")){ strLine1 = strLine1.replace("</MemoryDump>", ""); } output.write(newline); output.write(strLine1); I request you to kindly let me know how do I proceed with merging two XML files by adding additional content as well. It would be great if you could provide me some example links as well..! Thank You in Advance..! System.out.println(strLine1); } }

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• Maven best practice for generating multiple jars with different/filtered classes ?

  - by jaguard

  I developed a Java utility library (similarly to Apache Commons) that I use in various projects. Additionally to fat clients I also use it for mobile clients (PDA with J9 Foundation profile). In time the library that started as a single project spread over multiple packages. As a result I end up with a lot of functionality but not really needed in all the projects. Since this library is also used inside some mobile/PDA projects I need a way to collect just the used classes and generate the actual specialized jars Currently in the projects that area using this library, I have Ant jar tasks that generate (from the utility project) the specialized jar files (ex: my-util-1.0-pda.jar, my-util-1.0-rcp.jar) using include/exclude jar task features. This is mostly needed due to the generated jar size constraints for the mobile projects. Migrating now to Maven I just wonder if there are any best practices to arrive to something similar so I consider the following scenarios: [1] - additionally to the main jar artifact (my-lib-1.0.jar) also generating inside my-lib project the separate/specialized artifacts using classifiers (ex: my-lib-1.0-pda.jar) using Maven Jar Plugin or Maven Assembly Plugin filtering/includes ... I'm not very comfortable with this approach since it pollute the library with library consumers demands (filters) [2] - Create additional Maven projects for all the specialized clients/projects, that will "wrap" the "my-lib" and generate the filtered jar artifacts (ex: my-lib-wrapper-pda-1.0 ...etc). As a result, these wrapper projects will include the filtering (to generate the filtered artifact) and will depend just on the "my-lib" project and the client projects will depend on my-lib-wrapper-xxx-1.0 instead of my-lib-1.0. This approach my look problematic since even that will let "my-lib" project intact (with no additional classifiers & artifacts), basically will double the number of projects since for every client project I'll have one just to collect the needed classes from the "my-util" library ("my-pda-app" project will need a "my-lib-wrapper-for-my-pda-app" project/dependency) [3] - Into the every client project that use the library (ex: my-pda-app) add some specialized Maven plugins to trim - out (when generating the final artifact/package) the un-needed classes (ex: maven-assembly-plugin, maven-jar-plugin, proguard-maven-plugin) What is the best practice for solving this kind of problems in the "Maven way" ?!

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• MaxReceivedMessageSize adjusted, but still getting the QuotaExceedException with WCF

  - by djerry

  Hey guys, First of all, i have read the "millions" of post on this site and some blogs/forum post on other websites, and no answer is solving my problem. I'm my app, there's a possibility to import a txt or csv file with data. In the case of the error, the file contains 444 rows (file is 14,5 kB). When i try to send it to the server to process it, i get an QuotaExceedException, telling me to increase MaxReceivedMessageSize. So i changed it to a much higher value, but i'm still getting the same exception. I'm using the same exact items for client and server in system.servicemodel in my config file. Config snippet : <system.serviceModel> <bindings> <netTcpBinding> <binding name="NetTcpBinding_IMonitoringSystemService" closeTimeout="00:01:00" openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00" transactionFlow="false" transferMode="Buffered" transactionProtocol="OleTransactions" hostNameComparisonMode="StrongWildcard" listenBacklog="10" maxBufferPoolSize="2147483647" maxBufferSize="2147483647" maxConnections="500" maxReceivedMessageSize="2147483647"> <readerQuotas maxDepth="32" maxStringContentLength="100000" maxArrayLength="100000" maxBytesPerRead="100000" maxNameTableCharCount="100000" /> <reliableSession ordered="true" inactivityTimeout="00:10:00" enabled="false" /> <security mode="Message"> <transport clientCredentialType="Windows" protectionLevel="EncryptAndSign"> <extendedProtectionPolicy policyEnforcement="Never" /> </transport> <message clientCredentialType="Windows" /> </security> </binding> </netTcpBinding> </bindings> <client> <endpoint address="net.tcp://localhost:8000/Monitoring%20Server" binding="netTcpBinding" bindingConfiguration="NetTcpBinding_IMonitoringSystemService" contract="IMonitoringSystemService" > <!--name="NetTcpBinding_IMonitoringSystemService"--> <identity> <userPrincipalName value="DJERRYY\djerry" /> </identity> </endpoint> </client> </system.serviceModel> Can i use this sample for client and server config? And what should i not use in that case. Thanks in advance.

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• Help with Linq Expression - INotifyPropertyChanged

  - by Stephen Patten

  Hello, I'm reading the source code from the latest Prism 4 drop and am interested in solving this problem. There is a base class for the ViewModels that implements INotifyPropertyChanged and INotifyDataErrorInfo and provides some refactoring friendly change notification. protected void RaisePropertyChanged<T>(Expression<Func<T>> propertyExpresssion) { var propertyName = ExtractPropertyName(propertyExpresssion); this.RaisePropertyChanged(propertyName); } private string ExtractPropertyName<T>(Expression<Func<T>> propertyExpresssion) { if (propertyExpresssion == null) { throw new ArgumentNullException("propertyExpression"); } var memberExpression = propertyExpresssion.Body as MemberExpression; if (memberExpression == null) { throw new ArgumentException("The expression is not a member access expression.", "propertyExpression"); } var property = memberExpression.Member as PropertyInfo; if (property == null) { throw new ArgumentException("The member access expression does not access property.","propertyExpression"); } if (!property.DeclaringType.IsAssignableFrom(this.GetType())) { throw new ArgumentException("The referenced property belongs to a different type.", "propertyExpression"); } var getMethod = property.GetGetMethod(true); if (getMethod == null) { // this shouldn't happen - the expression would reject the property before reaching this far throw new ArgumentException("The referenced property does not have a get method.", "propertyExpression"); } if (getMethod.IsStatic) { throw new ArgumentException("The referenced property is a static property.", "propertyExpression"); } return memberExpression.Member.Name; } and as an example of it's usage private void RetrieveNewQuestionnaire() { this.Questions.Clear(); var template = this.questionnaireService.GetQuestionnaireTemplate(); this.questionnaire = new Questionnaire(template); foreach (var question in this.questionnaire.Questions) { this.Questions.Add(this.CreateQuestionViewModel(question)); } this.RaisePropertyChanged(() => this.Name); this.RaisePropertyChanged(() => this.UnansweredQuestions); this.RaisePropertyChanged(() => this.TotalQuestions); this.RaisePropertyChanged(() => this.CanSubmit); } My question is this. What would it take to pass an array of the property names to an overloaded method (RaisePropertyChanged) and condense this last bit of code from 4 lines to 1? Thank you, Stephen

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• Start a short video when an incoming call is detected, first case using the emulator.

  - by Emanuel

  I want to be able to start a short video on an incoming phone call. The video will loop until the call is answered. I've loaded the video onto the emulator sdcard then created the appropriate level avd with a path to the sdcard.iso file on disk. Since I'm running on a Mac OS x snow leopard I am able to confirm the contents of the sdcard. All testing has be done on the Android emulator. In a separate project TestVideo I created an activity that just launches the video from the sdcard. That works as expected. Then I created another project TestIncoming that creates an activity that creates a PhoneStateListener that overrides the onCallStateChanged(int state, String incomingNumber) method. In the onCallStateChanged() method I check if state == TelephonyManager.CALL_STATE_RINGING. If true I create an Intent that starts the video. I'm actually using the code from the TestVideo project above. Here is the code snippet. PhoneStateListener callStateListener = new PhoneStateListener() { @Override public void onCallStateChanged(int state, String incomingNumber) { if(state == TelelphonyManager.CALL_STATE_RINGING) { Intent launchVideo = new Intent(MyActivity.this, LaunchVideo.class); startActivity(launchVideo); } } }; The PhoneStateListener is added to the TelephonyManager.listen() method like so, telephonyManager.listen(callStateListener, PhoneStateListener.LISTEN_CALL_STATE); Here is the part I'm unclear on, the manifest. What I've tried is the following: <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.incomingdemo" android:versionCode="1" android:versionName="1.0"> <application android:icon="@drawable/icon" android:label="@string/app_name"> <activity android:name=".IncomingVideoDemo" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.ANSWER" /> <category android:name="android.intent.category.DEFAULT" /> </intent-filter> </activity> <activity android:name=".LaunchVideo" android:label="LaunchVideo"> </activity> </application> <uses-sdk android:minSdkVersion="2" /> <uses-permission android:name="android.permission.READ_PHONE_STATE"/> </manifest> I've run the debugger after setting breakpoints in the IncomingVideoDemo activity where the PhoneStateListener is created and none of the breakpoints are hit. Any insights into solving this problem is greatly appreciated. Thanks.

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• Constraint Satisfaction Problem

  - by Carl Smotricz

  I'm struggling my way through Artificial Intelligence: A Modern Approach in order to alleviate my natural stupidity. In trying to solve some of the exercises, I've come up against the "Who Owns the Zebra" problem, Exercise 5.13 in Chapter 5. This has been a topic here on SO but the responses mostly addressed the question "how would you solve this if you had a free choice of problem solving software available?" I accept that Prolog is a very appropriate programming language for this kind of problem, and there are some fine packages available, e.g. in Python as shown by the top-ranked answer and also standalone. Alas, none of this is helping me "tough it out" in a way as outlined by the book. The book appears to suggest building a set of dual or perhaps global constraints, and then implementing some of the algorithms mentioned to find a solution. I'm having a lot of trouble coming up with a set of constraints suitable for modelling the problem. I'm studying this on my own so I don't have access to a professor or TA to get me over the hump - this is where I'm asking for your help. I see little similarity to the examples in the chapter. I was eager to build dual constraints and started out by creating (the logical equivalent of) 25 variables: nationality1, nationality2, nationality3, ... nationality5, pet1, pet2, pet3, ... pet5, drink1 ... drink5 and so on, where the number was indicative of the house's position. This is fine for building the unary constraints, e.g. The Norwegian lives in the first house: nationality1 = { :norway }. But most of the constraints are a combination of two such variables through a common house number, e.g. The Swede has a dog: nationality[n] = { :sweden } AND pet[n] = { :dog } where n can range from 1 to 5, obviously. Or stated another way: nationality1 = { :sweden } AND pet1 = { :dog } XOR nationality2 = { :sweden } AND pet2 = { :dog } XOR nationality3 = { :sweden } AND pet3 = { :dog } XOR nationality4 = { :sweden } AND pet4 = { :dog } XOR nationality5 = { :sweden } AND pet5 = { :dog } ...which has a decidedly different feel to it than the "list of tuples" advocated by the book: ( X1, X2, X3 = { val1, val2, val3 }, { val4, val5, val6 }, ... ) I'm not looking for a solution per se; I'm looking for a start on how to model this problem in a way that's compatible with the book's approach. Any help appreciated.

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• Strange iPhone memory leak in xml parser

  - by Chris

  Update: I edited the code, but the problem persists... Hi everyone, this is my first post here - I found this place a great ressource for solving many of my questions. Normally I try my best to fix anything on my own but this time I really have no idea what goes wrong, so I hope someone can help me out. I am building an iPhone app that parses a couple of xml files using TouchXML. I have a class XMLParser, which takes care of downloading and parsing the results. I am getting memory leaks when I parse an xml file more than once with the same instance of XMLParser. Here is one of the parsing snippets (just the relevant part): for(int counter = 0; counter < [item childCount]; counter++) { CXMLNode *child = [item childAtIndex:counter]; if([[child name] isEqualToString:@"PRODUCT"]) { NSMutableDictionary *product = [[NSMutableDictionary alloc] init]; for(int j = 0; j < [child childCount]; j++) { CXMLNode *grandchild = [child childAtIndex:j]; if([[grandchild stringValue] length] > 1) { NSString *trimmedString = [[grandchild stringValue] stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]; [product setObject:trimmedString forKey:[grandchild name]]; } } // Add product to current category array switch (categoryId) { case 0: [self.mobil addObject: product]; break; case 1: [self.allgemein addObject: product]; break; case 2: [self.besitzeIch addObject: product]; break; case 3: [self.willIch addObject: product]; break; default: break; } [product release]; } } The first time, I parse the xml no leak shows up in instruments, the next time I do so, I got a lot of leaks (NSCFString / NSCFDictionary). Instruments points me to this part inside CXMLNode.m, when I dig into a leaked object: theStringValue = [NSString stringWithUTF8String:(const char *)theXMLString]; if ( _node->type != CXMLTextKind ) xmlFree(theXMLString); } return(theStringValue); I really spent a long time and tried multiple approaches to fix this, but to no avail so far, maybe I am missing something essential? Any help is highly appreciated, thank you!

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• [NEWVERSION]algorithm || method to write prog[UNSOLVED] [closed]

  - by fatai

  I am one of the computer science student. Everyone solve problem with a different or same method, ( but actually I dont know whether they use method or I dont know whether there are such common method to approach problem.) if there are common method, What is it ? If there are different method, which method are you using ? All teacher give us problem which in simple form sometimes, but they donot introduce any approach or method(s) so that we cannot make a decision to choose the method then apply that one to problem , afterward find solution then write code.No help from teacher , push us to find method to solve homework. Ex: my friend is using no method , he says "I start to construct algorithm while I try to write prog." I have found one method when I failed the course, More accurately, my method: When I counter problem in language , I will get more paper and then ; first, input/ output step ; my prog will take this / these there argument(s) and return namely X , ex : in c, input length is not known and at same type , so I must use pointer desired output is in form of package , so use structure second, execution part ; in that step , I am writing all step which are goes to final output ex : in python ; 1.) [ + , [- , 4 , [ * , 1 , 2 ]], 5] 2.) [ + , [- , 4 , 2 ],5 ] 3.) [ + , 2 , 5] 4.) 7 ==> return 7 third, I will write test code ex : in c++ input : append 3 4 5 6 vector_x remove 0 1 desired output vector_x holds : 5 6 now, my other question is ; What is/are other method(s) which have/has been; used to construct class :::: for c++ , python, java used to communicate classes / computers used for solving embedded system problem ::::: for c by other user? Some programmer uses generalized method without considering prog-language(java , perl .. ), what is this method ? Why I wonder , because I learn if you dont costruct algorithm on paper, you may achieve your goal. Like no money no lunch , I can say no algorithm no prog therefore , feel free when you write your own method , a way which is introduced by someone else but you are using and you find it is so efficient

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• string categorization strategies

  - by Andrew Heath

  I'm the one-man dev team on a fledgling military history website. One aspect of the site is a catalog of ~1,200 individual battles, including the nations & formations (regiments, divisions, etc) which took part. The formation information (as well as the other battle info) was manually imported from a series of books by a 10-man volunteer team. The formations were listed in groups with varying formatting and abbreviation patterns. At the time I set up the data collection forms I couldn't think of a good way to process that data... and elected to store it all as strings in the MySQL database and sort it out later. Well, "later" - as it tends to happen - has arrived. :-) Each battle has 2+ records in the database - one for each nation that participated. Each record has a formations text string listing the formations present as the volunteer chose to add them. Some real examples: 39th Grenadier Rgmt, 26th Volksgrenadier Division 2nd Luftwaffe Field Division, 246th Infantry Division 247th Rifle Division, 255th Tank Brigade 2nd Luftwaffe Field Division, SS Cavalry Division 28th Tank Brigade, 158th Rifle Division, 135th Rifle Division, 81st Tank Brigade, 242nd Tank Brigade 78th Infantry Division 3rd Kure Special Naval Landing Force, Tulagi Seaplane Base personnel 1st Battalion 505th Infantry Regiment The ultimate goal is for each individual force to have an ID, so that its participation can be traced throughout the battle database. Formation hierarchy, such as the final item above 1st Battalion (of the) 505th Infantry Regiment also needs to be preserved. In that case, 1st Battalion and 505th Infantry Regiment would be split, but 1st Battalion would be flagged as belonging to the 505th. In database terms, I think I want to pull the formation field out of the current battle info table and create three new tables: FORMATION [id] [name] FORMATION_HIERARCHY [id] [parent] [child] FORMATION_BATTLE [f_id] [battle_id] It's simple to explain, but complicated to enact. What I'm looking for from the SO community is just some tips on how best to tackle this problem. Ideally there's some sort of method to solving this that I'm not aware of. However, as a last resort, I could always code a classification framework and call my volunteers back to sort through 2,500+ records...

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• Creating a spam list with a web crawler in python

  - by user313623

  Hey guys, I'm not trying to do anything malicious here, I just need to do some homework. I'm a fairly new programmer, I'm using python 3.0, and I having difficulty using recursion for problem-solving. I've been stuck on this question for quite a while. Here's the assignment: Write a recursive method spam(url, n) that takes a url of a web page as input and a non-negative integer n, collects all the email address contained in the web page and adds them to a global dictionary variable spam_dict, and then recursively calls itself on every http hyperlink contained in the web page. You will use a dictionary so only one copy of every email address is save; your dictionary will store (key,value) pairs (email, email). The recursive call should use the parameter n-1 instead of n. If n = 0, you should collect the email addresses but no recursive calls should be made. The parameter n is used to limit the recursion to at most depth n. You will need to use the solutions of the two above problems; you method spam() will call the methods links2() and emails() and possibly other functions as well. Notes: 1. running spam() directly will produce no output on the screen; to find your spam_dict, you will need to read the value of spam_dict, and you will also need to reset it to the empty dictionary before every run of spam. 2. Recall how global variables are used. Usage: spam_dict = {} spam('http://reed.cs.depaul.edu/lperkovic/csc242/test1.html',0) spam_dict.keys() dict_keys([]) spam_dict = {} spam('http://reed.cs.depaul.edu/lperkovic/csc242/test1.html',1) spam_dict.keys() dict_keys(['[email protected]', '[email protected]']) So far, I've written a function that traverses web pages and puts all the links in a nice little list, and what I wanted to do was call that functions. And why would I use recursion on a dictionary? And how? I don't understand how n ties into all of this. def links2(url): content = str(urlopen(url).read()) myparser = MyHTMLParser() myparser.feed(content) lst = myparser.get() mergelst = [] for link in lst: mergelst.append(urljoin(lst[0],link)) print(mergelst) Any input (except why spam is bad) would be greatly appreciated. Also, I realize that the above function could probably look better, if you have a way to do it, I'm all ears. However, all I need is the point is for the program to produce the proper output.

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• How do we, as a community, help encourage programming in public schools? (Or state Schools for the U

  - by NoMoreZealots

  PRIMARY MOTIVATION My office gets involved with the "First Robotics" competitions and one thing that lingers year to year is the students typically have no preparation for doing even simple programming as part of the public schools system. While the science classes provide some basic grasp of mechanical and electrical concepts, by in large computer programming gets no coverage from the curriculum. (This my be different in other areas of the country/world.) What makes it worse is there is only a short period of time you have to prepare the student's and help them design the robot. Talking to some professors from local colleges, it's a problem because you can't assume even the most basic understanding for freshman CS majors. Languages like Python, Lua and BASIC are simple enough for at least high school level students, if not younger. SCOPE So how do you get public schools to support a programming, at least to the level of "Try it in BASIC" examples that used to be at the end of a chapter in my Algebra book? At least enough to prepare them for event's such as the FIRST Robotic competitions. Which the primary objectives are to teach problem solving and team work, and to possible foster an interest in Math, Science and Engineering in general. (Not force feed to them, as some people her seem to be implying.) Edit: Why teach kids: (Since 2000 CS enrollment in US colleges has decreased by 70% while college enrollment has increased, this is a PROBLEM.) Saying there is no value in teaching someone programming in Jr./High school because they might think "they know programming." Is like saying there's no value in teaching High school science and physics, because they might decide they "know physics." Leading to abuse like: "I passed a high school physics class, I'm going to develop a Unified Quantum Gravitational Theory." Better Prepared students are better students. Instead it would allows college programs to raise the bar on the entry level courses, allowing students to be weeded out based on their understanding of more advanced material. Plus people who did poorly in that in topic in High school aren't as likely to say "I think there's money in computer's so I'll computer science." Plus if people take it in high school and decide THEN that it's not for them, it's better than them wasting their money to PAY a college to figure that out. The result is that people who take the degree are more likely to succeed and be there for the RIGHT reasons. (i.e. It's what they REALLY want to do. And that's REALLY the key to being good at anything.) Programming is like anything else, the more practice and genuine interest you have the better you get. If you start them later, they get less practice. The earlier give them the opportunity to start, the more practice they will get. All other things equal, the more practice the better the programmer.

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• (resolved) empty response body in ajax (or 206 Partial Content)

  - by Nikita Rybak

  Hi guys, I'm feeling completely stupid because I've spent two hours solving task which should be very simple and which I solved many times before. But now I'm not even sure in which direction to dig. I fail to fetch static content using ajax from local servers (Apache and Mongrel). I get responses 200 and 206 (depending on the server), empty response text (although Content-Length header is always correct), firebug shows request in red. Javascript is very generic, I'm getting same results even here: http://www.w3schools.com/ajax/tryit.asp?filename=tryajax_first (just change document location to 'http://localhost:3000/whatever') So, it's probably not the cause. Well, now I'm out of ideas. I can also post http headers, if it'll help. Thanks! Response Headers Connection close Date Sat, 01 May 2010 21:05:23 GMT Last-Modified Sun, 18 Apr 2010 19:33:26 GMT Content-Type text/html Content-Length 7466 Request Headers Host localhost:3000 User-Agent Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3 Accept text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language en-us,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 115 Connection keep-alive Referer http://www.w3schools.com/ajax/tryit_view.asp Origin http://www.w3schools.com Response Headers Date Sat, 01 May 2010 21:54:59 GMT Server Apache/2.2.14 (Unix) mod_ssl/2.2.14 OpenSSL/0.9.8l DAV/2 mod_jk/1.2.28 Etag "3d5cbdb-fb4-4819c460d4a40" Accept-Ranges bytes Content-Length 4020 Cache-Control max-age=7200, public, proxy-revalidate Expires Sat, 01 May 2010 23:54:59 GMT Content-Range bytes 0-4019/4020 Keep-Alive timeout=5, max=100 Connection Keep-Alive Content-Type application/javascript Request Headers Host localhost User-Agent Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3 Accept text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language en-us,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 115 Connection keep-alive Origin null UPDATED: I've found a problem, it was about cross-domain requests. I knew that there are restrictions, but thought they're relaxed for local filesystem and local servers. (and expected more descriptive error message, anyway) Thanks everybody!

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• What's the best Scala build system?

  - by gatoatigrado

  I've seen questions about IDE's here -- Which is the best IDE for Scala development? and What is the current state of tooling for Scala?, but I've had mixed experiences with IDEs. Right now, I'm using the Eclipse IDE with the automatic workspace refresh option, and KDE 4's Kate as my text editor. Here are some of the problems I'd like to solve: use my own editor IDEs are really geared at everyone using their components. I like Kate better, but the refresh system is very annoying (it doesn't use inotify, rather, maybe a 10s polling interval). The reason I don't use the built-in text editor is because broken auto-complete functionalities cause the IDE to hang for maybe 10s. rebuild only modified files The Eclipse build system is broken. It doesn't know when to rebuild classes. I find myself almost half of the time going to project-clean. Worse, it seems even after it has finished building my project, a few minutes later it will pop up with some bizarre error (edit - these errors appear to be things that were previously solved with a project clean, but then come back up...). Finally, setting "Preferences / Continue launch if project contains errors" to "prompt" seems to have no effect for Scala projects (i.e. it always launches even if there are errors). build customization I can use the "nightly" release, but I'll want to modify and use my own Scala builds, not the compiler that's built into the IDE's plugin. It would also be nice to pass [e.g.] -Xprint:jvm to the compiler (to print out lowered code). fast compiling Though Eclipse doesn't always build right, it does seem snappy -- even more so than fsc. I looked at Ant and Maven, though haven't employed either yet (I'll also need to spend time solving #3 and #4). I wanted to see if anyone has other suggestions before I spend time getting a suboptimal build system working. Thanks in advance! UPDATE - I'm now using Maven, passing a project as a compiler plugin to it. It seems fast enough; I'm not sure what kind of jar caching Maven does. A current repository for Scala 2.8.0 is available [link]. The archetypes are very cool, and cross-platform support seems very good. However, about compile issues, I'm not sure if fsc is actually fixed, or my project is stable enough (e.g. class names aren't changing) -- running it manually doesn't bother me as much. If you'd like to see an example, feel free to browse the pom.xml files I'm using [github]. UPDATE 2 - from benchmarks I've seen, Daniel Spiewak is right that buildr's faster than Maven (and, if one is doing incremental changes, Maven's 10 second latency gets annoying), so if one can craft a compatible build file, then it's probably worth it...

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