ConvertAll - Conversia unei liste mult mai usor

Avem urmatorul scenariu. O lista de elemente de tip A, pe care trebuie sa o convertim la o lista de tip B. Pentru a putea rezolva aceasta problema putem să implementam operatorul implicit sau explicit de conversie, iar apoi să iteram prin lista pentru a face conversia la tipul B.

List<A> listaA;
List<B> listaB;
...
foreach(A a in listaA)
{
    listaB.Add(a);
}

sau

listaB.foreach(item=>listaB.Add(item));

Ambele soluții sunt rezonabile, dar e puțin mai greu de înțeles ca in spate se face o conversie. Pentru a face codul mai clar putem să facem in felul următor:

listaB = listaA.ConvertAll<B>(item => item)

Ce am scris mai sus? Fiecare element din listaA convertestel in tipul B si adaug-al in colecția care rezulta. item => item am putut sa scrie deoarece am presupus ca un operator de conversie implicita sau explicita intre cele doua tipuri a fost deja implementat.
In cazul in care acesta nu ar fi implementat am avea ceva asemanator:
Din

private B ConvertAToB(A a) { return new B(); ... }
...
List<A> listaA;
List<B> listaB;
...
foreach(A a in listaA)
{
    listaB.Add(ConvertAToB(a));
}

Am avea:

private B ConvertAToB(A a) { return new B(); ... }
...
listaB = listaA.ConvertAll<B>(item => ConvertAToB(item));

Cea ce am scris mai sus se poate scrie si:

listaB = listaA.ConvertAll<B>(ConvertAToB);

Chiar daca folosim ConvertAll obtinem acelasi rezultat, doar ca folosind ConvertAll obtinem un cod mai clar. Urmatorul dezvoltator care o sa vina dupa noi o sa inteleaga ca aici facem oconversie.

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Cum sa verificam daca un path este valid

Uneori avem nevoie să verificam dacă un path dat de utilizator este valid. Asa cum exista System.IO.File.Exist() exista pentru a face aceasta verificare si System.IO.Directory.Exist().
Iata mai jos si un exemplu:

string path = "d:/locatie";
if(System.IO.Directory.Exist(path))
{
     //path-ul este valid.
} else
{
     // path-ul nu este valid.
}

In cazul in care path-ul contine si numele unui fisier putem sa facem urmatorul artificiu:

string path = "d:/locatie/a.txt";
if(System.IO.Directory.Exist(GetDirectoryName(path)))
{
     //path-ul este valid.
} else
{
     // path-ul nu este valid.
}

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Cand sa folosim System.Thread.Timer

In .NET putem sa alegem din 3 tipuri de timer:

• System.Timer - thread timer;
• System.Thread.Timer - server base timer;
• System.Windows.Forms.Timer - windows base timer;

System.Windows.Forms.Timer se foloseste in general pe UI, cand trebuie sa facem update. System.Timer o sa il folosim de obicei de obicei pe partea de server cand vrem mai multe flexibilitate si mai mult optiuni. Din cele trei timer-uri, acesta are cele mai multe optiuni.
System.Thread.Timer, care rulează un nou thread pentru operațiile sale. Acesta este folositor când vrem sa facem operații asyncron.

System.Threading.Timer timer = new System.Threading.Timer(new TimerCallback(ExecutaCeva), null, 0, 2000);
...
private void ExecutaCeva(object obj)
{
....
}

Pentru a face disable/enable putem sa folosim:
timer.Change(Timeout.Infinite, Timeout.Infinite); //Disable.
timer.Change(0, 2000); //Enable.
Cea ce mi s-a parut foarte folositor la acest imer sunt parametrii lui Change si ultimii doi parametrii a contructorului. Prin intermediul lor putem sa specificam dupa ce perioada sa se apeleze metoda ExecutaCeva, iar apoi la ce interval de timp aceasta sa fie executa.
Sunt cazuri cand vrem ca primul apel ExecutaCeva sa fie facut dupa 1 secunda, iar apoi timer-ul sa apeleze aceasta metoda la 10 secunte. Pentru acest lucru daac am folostii System.Timer ar fi nevoie sa oprim timer-ul dupa prima executie, sa setam din nou intervalul de timp, iar apoi sa îl pornim din nou.

System.Thread.Timer ne permite sa facem in felul urmator:
System.Threading.Timer timer = new System.Threading.Timer(new TimerCallback(ExecutaCeva), null, 1000,10000);

varianta care o prefer eu este:

System.Threading.Timer timer = new System.Threading.Timer(new TimerCallback(ExecutaCeva), null, TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(10));

Este bine de stiut ca orice moment cand apelam metoda Change, timpul pana cand se apeleaza ExecutaCeva se modifica. Daca prima valoare este 0, atunci metoda pentru callback se apeleaza imediat, iar daca este Timer.Infinite atunci timer-ul este disable.
Cand al doilea parametru este 0 sau Timer.Infine, atuci timer-ul se executa o singura data.

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Cum sa salvezi un stream direct intr-un fisier

Cred ca este a 2-a oara când întâlnesc aceasta cerința in decurs de câteva săptămâni.
Se da un stream și o locație unde trebuie salvat, se cere să se salveze conținutul la stream in locația data. Din păcate API-ul de .NET nu ne permite să facem acest lucru doar dintr-un apel.
O soluție propusa este următoarea:

        /// <summary>
       /// Save the stream to the given location.
       /// </summary>
       /// <param name="stream">The stream.</param>
       /// <param name="filePath">The file path where is saved.</param>
       /// <param name="blockSize">The size of the buffer(in kB)</param>
       public static void SaveStream(this Stream stream,String filePath,SeekOrigin seekOrigin=SeekOrigin.Begin,int blockSize=1)
       {
           //Set the poinder to the begin of the stream.
           if(stream.CanSeek && seekOrigin==SeekOrigin.Begin)
           {
               stream.Seek(0, SeekOrigin.Begin);
           }

           //Removed the existing file.
           if (File.Exists(CommandLineArguments.Instance.File))
           {
               File.Delete(CommandLineArguments.Instance.File);
           }

           //Save the stream to the given location.
           using (var streamWrite = File.Create(CommandLineArguments.Instance.File))
           {
               byte[] buffer = new byte[1024*blockSize];
               int read;

               while ((read = stream.Read(buffer, 0, buffer.Length)) > 0)
               {
                   streamWrite.Write(buffer, 0, read);
               }
           }
       }

Iar un exemplu de utilizare:

Stream stream=...;
stream.Save("d:/a.txt");

In funcție de necesitați acest exemplu se poate extinde. Din păcate nu putem să facem un extension method pe File deoarece este o clasa statica.

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New mLearning Authoring Offerings - Wave #1

As detailed in my list of mobile learning predictions for 2011, a collection of smart and savvy authoring tool vendors offering solutions for online training delivery will start to introduce specialized tools that will enable some form of single sourcing that outputs mobile-friendly content with little or nominal effort over and above what's already been invested to create online courseware and training materials.  It took no longer than the end of January for new product announcements to be made by two of the leading authoring tool vendors who are now offering both Flash and HTML5 course publication output options to instructional designers using their respective applications. Let's take a quick look at both companies and their respective offerings:

Rapid Intake's mLearning Studio.  Garin Hess and his team over at Rapid Intake have announced a new suite of tools called mLearning Studio that will allow content authors to output SCORM-conformant courseware along with included assessments as either web-friendly Flash courseware or mobile-friendly HTML5 packages with the click of a button.  I got to play around with some early content samples and found their mobile packaging to be clean, flexible and very well structured for playback on compatible mobile devices based on Apple's iOS or on Android-based mobiles or tablets. We are still experimenting to determine if the produced content can be easily managed when downloaded and secured to a mobile device for offline playback using the app-based approach but online delivery works quite nicely with gesture-based navigation, nice media support and engaging assessment capabilities.  Moreover, we really like what we see in their "version 1.0" effort here and look forward to seeing where they can take it all when supporting legacy mobile devices like the ever popular BlackBerry in the enterprise as well as newer smartphones like those based on Microsoft's Windows Phone 7 OS that don't fully support the HTML5 spec as of yet. Rapid Intake is considering releasing their mobility options as both a standalone mlearning authoring tool as well as via an extension to their core Unison offering. You can learn more about the upcoming release of mLearning Studio in a video featured on their web site here.

Harbinger Group's Raptivity.  Raptivity is a well regarded "rapid interactivity builder" application used by many companies to "add some spice" to their online learning courses through the delivery of interactive exercises. To facilitate wider mobile delivery of these interactions, Vikas Joshi and his team over at Harbinger have added new functionality that allows IDs to output defined interactions as either Flash or HTML5 packages that can then be assigned and taken via online or offline delivery.  No word yet as to whether the mobile-friendly Raptivity interactions can also be embedded into a Rapid Intake mLearning Studio-based mobile course but given these two companies have interacted fully in the past, its logical to think they will at some point. You can learn more about the new mobile-friendly Raptivity offering here.

We are excited every time new tools are introduced and these two organizations are leading the way in 2011 by delivering viable options for mobile learning content creation and delivery where there's much to gain and not much at all IDs need to learn to make the jump from online to mobile for their learning communities.

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mLearning Tech A’plenty Released at CES 2011

It is the first week in January and the annual International CES (“Consumer Electronics Show”) is in full swing out in Las Vegas – just as if Santa Claus came twice within a two-week period for gadget freaks and tech nerds alike. This year’s event is as big as ever with 100K+ attendees roaming through 2,700 vendor booths across multiple sites. In the midst of all the new 3D TVs, streaming home entertainment, futuristic toys and smart appliances, the primary market focus of this year’s show seems to be on mobility with smartphones, tablets and apps taking center stage in many of the main keynotes and featured front-and-center in larger vendor booths. And many of these advances drive the potential and increase the affordances of mobile learning and performance support across the enterprise.

Better Devices. It is starting to feel like the smartphone is finally going to start replacing the feature phone inside every knowledge worker’s pocket or purse; I’m not saying my mom is going to replace her Jitterbug anytime soon but she’s a grandmother not an enterprise employee. For those of us with the means and the desire, the choices are plentiful and reasonable in most markets and the up-trending Bring Your Own Device movement is starting to influence IT departments to allow newer Apple iOS, Google Android and Microsoft Windows Phone7 devices to coexist on the highly restricted/locked down networks IT has operated in the past. As security and control issues for enterprise-grade mlearning solutions are mitigated to infosec’s satisfaction, BYOD policies can actually save organization tremendous amounts of money every year. CES showcased a myriad of Android smartphones and tablet devices for consumers from Motorola, HTC, Samsung, LG, Sony Erickson, Dell and many others plus specialized offerings from Cisco Systems on the enterprise end of the spectrum to Vizio on the consumer end; that said, most every contemporary Android device can install/run an “app” and that brings an opportunity for learning closer to any worker in the time of need.

Tablets devices are all the rage at CES as vendors from across the world all seek to cash in on Apple’s success with their iPad. Tablets ranging in size from pocket minis to full-sized and dockable slates are featured everywhere with many supporting the newer Android 3.0/Honeycomb OS, Windows 7/Phone 7 and even some Linux variations. Tablets from the “tier one players” will obviously have an impact on the market and the fact that many of them run Flash content makes them ultra-appealing for mobile learning situations. The real question is whether the application ecosystems that surround each of these new devices can overcome the market lead Apple’s current (and future) generation iPads already enjoy. I suspect we’ll see Apple conceding some nominal but measurable market share to the new crème of the crop and this will drive most enterprise organizations to need to support multiple tablets in much the same way they support multiple smartphones for their enterprise mobile learning initiatives. I anticipate seeing projects with lots of iPads alongside several Android tabs and a smattering of BlackBerry PlayBooks all coexisting in one learning deployment. Thus, great things are coming along with increased complexity for content creation, management and distribution since the cool Flash content won't play across the range of devices an enterprise must manage for their mobile learning programs.

Way Faster Networks. To me, the more significant advances introduced at CES 2011 were the formal introductions from the leading carriers of their much anticipated “4G”, high-speed networks. All four of the major US wireless carriers (ATT, Verizon Wireless, T-Mobile and Sprint) plus several others announced support for next-gen device communications resulting in faster access speeds. These faster networks drive the need/desire for more capable smartphones and tablet devices that can leverage the network benefits. What’s needed are better applications to serve as the third leg of the new “technology stool” and enterprise mobile learning represents one of the real world examples that can take advantage of these faster networks, better devices and richer learning experiences anytime and anywhere.

In summary, this year’s show seems bigger and more impressive than many in recent years and I believe many of the products and services introduced this week will play a critical role in the adoption and proliferation of enterprise mobile learning here and abroad. And the gadget geek in me really looks forward to getting a new device (or four!) in the coming weeks and months as we push the future of tech into the future of learning.

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GeoLearning Acquired by SumTotal: The mLearning Impact?

 The enterprise learning market witnessed another big consolidation event today as SumTotal Systems announced it acquired GeoLearning thus further positioning SumTotal as the largest platform provider for LMS and talent management solutions in the industry. According to leading analyst Josh Bersin, the combined entity will grow SumTotal's "total market share to 12.5% ... (and) makes SumTotal approximately 50% larger than the #2 LMS player (Saba), clearly establishing their leadership in the market."  Interesting news indeed.

So, what does this move mean to the enterprise mobile learning market? 

From my perspective, both companies have worked on "baking and serving up" a mobile learning strategy to one extent or another but both have placed a higher priority on building out their talent management suites rather than their mobility solutions -- for good reason too as that's where the money has been in recent years as mobile has been taking shape. SumTotal's ToolBook authoring tool, now in version 10.x, is a well crafted desktop-based application that we've used many times in the past to help design and produce mobile learning content that can be packaged for delivery with many different enterprise mobile learning platforms including our own, Intuition's and others. There are also nice hooks in place to allow mobile-ready courses to be accessed by mlearners via the SumTotal LMS using a mobile web browser but SumTotal has yet to take the leap from basic "mobile web" delivery into the more sophisticated and polished "mobile app" methods.

GeoLearning, on the other hand, has made solid strides in recent months with their GeoMaestro Mobility Solution to design and develop their own mobile apps (for iPhone, iPad, Android and WebOS/Palm-based devices) and provide a continuum of mobile authoring, delivery and reporting via their GeoMaestro suite to the benefit of their customers now considering mobile learning for the first time (and who isn't?). I certainly applaud their efforts to get into the pool but I can state with conviction that any "version 1.0" effort only represents the first steps on a long journey as we move into the highly complex arena of mobility with its vastly different technologies and delivery models when compared with delivering online content in the enterprise LMS space. In short, "getting a course on a phone" is relatively easy while the 250+ other things the  enterprise is now concerned with represent the challenges that need to be addressed to ensure the learning experience is fully functional, appropriate, customizable, secure and fully scalable. But actually getting a version 1.0 out the door IS an important start! Geo's new "client-side" tools/apps may represent a key ingredient for SumTotal's push into the enterprise mobile learning market but, unfortunately, the official press release doesn't mention mobile in any shape or fashion. 

SumTotal would be well served to take a quick and hard look at the GeoLearning tools and figure out how they can start to leverage them under the bigger umbrella this consolidation represents as it will serve their combined customer base well. And the increased visibility and adoption of mobile learning across the broader market is good news for everyone in the enterprise mLearning space as more and more companies seek solutions that can meet their current and future requirements.

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