Windows Live - Introducere

Windows LIVE series:

• Introducere
• Web Authentication
• Live Connect
• Basic Operations
• SkyDrive
  

Acesta este primul post dintr-o serie de posturi in care osa discutam despre Microsoft Live ID. O sa discutam mai ales din perspectivaunui dezvoltator. Inainte sa incepem sa vorbim despre Live ID, cred ca estenecesar sa vedem ce inseamna OpenID.

OpenID is an open standard that describes how users can be authenticated in a decentralized manner, eliminating the need for services to provide their own ad hoc systems and allowing users to consolidate their digital identities.

Sursa: Wikipedia

Pentru noi, ca si dezvoltatori de aplicatii web, mobile saudesktop acest lucru inseamna ca putem sadezvoltam aplicatii care permit utilizatoriilor sa se autentifice cu un user deLive Id, Facebook, Yahoo, Google. Open ID ne ofera mecanismul prin care putemsa verificam identitatea unui user, userul X este perosana care predinte caeste defapt.

Din cei trei de AAA(Authentification, Autorization, Accounting), OpenID ne ajuta sa rezolvam primulA – Authentification. In general, partea de autorizare si de tracking trebuiesa o facem in interiorul aplicatiei noastre. Uneori exista mai multe sistemecare sunt integrate intre ele, a.i. partea de autorizare se face intr-un singurloc, dar acesta este un caz particular.

Exista mai multe moduri prin care un user se poateautententifica in system folosind OpenId( url, token, password, smart cards,amprenta etc). OpenID fiind un standard nu impune modul prin care un usertrebuie sa se autentifice.

In procesul de autentificare folosind OpenID sunt implicate 3sisteme care comunica intre ele:

• User device – deviceul de pe care userul vrea sa accesezeaplicatia noastra
• Identify Provider (OpenID provider) - sistemul pe care il folosim pentruautentificare
• Relying Party – aplicatia noastra

Scenariul este urmatorul:

Un user doreste sa se autentifice in aplicatia noastra. In locsa introduca user si parola, acesta o sa selecteze Identify Provider-ul pe careil foloseste. Identify Provider nu trebuie sa fie neaparat unul cunoscut.Userul poate sa introduca doar un URL si sa predinta ca URL-ul respective estea lui. Relying party trebuie sa contacteze identify provider si sa asociezerequestul facut de user (in general intre indentity provider si relying partyse face un schimb de token-uri). Dupa acest pas relying party o sa faca unrequest de autentificare la idenfity provider, care o sa deschida o fereastrade log-in la end-user. Userul isi va introduce credentialele lui, care urmeazasa fie verificate de catre identify provider. Dupa acest pas identify providero sa raspunda la relying party daca autentificarea a avut loc cu success. Pebaza acestui raspuns userul se va autentifica in sistemul nostru.

Raspunsul care vine de la identify provider nu o sa vina asaimediat. In functie de cat de repede introduce userul credentialele, raspunsulpoate sa vina in 10 secunde sau in 2 minute. Exista diferite implentari pentrumecanismul prin careidentify provider notifica relying party daca autentificareaa avut loc cu success. In implementarea standard, identify provider apeleazarelying party (se face un submit la o anumita adresa) si ii trasmite dacaautentificarea a avut loc cu success.

Mai jos puteti sa gasiti modul in care se schimba informatia in momentul in care se foloseste OpenID.

1. Send user’s URL

2. Redirect user to get token from OP

3. Get token from OP

4. User post credentials to OP

5. Redirect token is send back to the relying partyusing user device

6. Redirect token is send back to the relying partyusing user device

Dupa cum ati putut observa in schema de mai sus, inate saputem folostii un provider de Open ID este necesar sa ne inregistram la acesta.

In general fiecare identify provider ofera diferitefunctionalitati pe langa cele de baza( informatii suplimentare despre user:nume, sex, varsta, language, etc).

Microsoft Live Id-ul este mecanismul de identify provider pecare il foloseste Microsoft. Acesta nu trebuie folosit doar de catreaplicatiile Microsoft, poate sa fie folosit in orice fel de aplicatie. Existamai multe modalitati prin care ne putem creea un count de Live Id, uneori necream unul fara sa ne dam seama. Daca avem un cont de Hotmail, WindowsMessenger sau .NET Passport atunci deja avem si un cont de LiveId.

Din punct de vedere istoric, prima data a aparut Hotmail,urmat de .NET Passport, iar apoi Windows Live ID. Din 2007 Microsoft a lansatSDK-ul de Live ID prin intermediul caruia orice dezvoltator, putea sa integrezeLive ID in aplicatia lui, indiferent de limbajul si/sau platforma. Din 2008, Microsofta anuntat ca suporta standardul OpenID in totalitate.

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LINQ: ToDictionary

Se da o lista de obiecte care trebuie convertite intr-un dictionar.
O prima implementare la aceasta ar putea sa fie:

Dictionary<string,Car> dictionary=new Dictionary<string, Car>();
            foreach (var car in cars)
            {
                dictionary.Add(car.Code,car);
            }

Putem avea diferite implementări, in diferite moduri. Ce nu trebuie sa uitam ca LINQ ne ofera aceasta posibilitate folosind metoda "ToDictionary".
Cea mai simpla varianta primeste un singur parametru, care specifica cheia key-ul care o sa fie folosit pentru fiecare element care se adauga in dictionar:

Dictionary<string,Car> dictionary= cars.ToDictionary(car => car.Code);

Un alt overload la aceasta metoda ne permite sa specificam si item-ul care se adauga pentru key-ul dat:

Dictionary<string, string> dictionary = cars.ToDictionary(car => car.Code, car => car.Model);

Spor!.

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ReadOnlyDictionary in .NET 4.0 and 4.5

.NET 4.5 aduce destul de multe feature noi. Insa pana o sa fie adoptat pe proiectele in curs o sa treaca o perioada destul de lunga. Unele din aceste feature le putem avea si in .NET 4.0, doar ca trebuie sa scriem putin cod.
In .NET 4.5 daca avem nevoie de un dictionar care sa fie read-only este destul de simplu. Avem la dispozitie interfata IReadOnlyDictionary si implementarea acesteia. Implementarea poate sa fie gasita in namespace-ul System.Collections.Generic din 4.5.

Dictionary<int, string> dictionary = new Dictionary<int, string>();
            dictionary.Add(1, "first");
            dictionary.Add(2, "second");

            ReadOnlyDictionary<string, int> readOnlyDictionary =
                new ReadOnlyDictionary<string, int>(dictionary);

Ce este bine de stiut ca operatiile de add/edit/delete inca exista, doar ca in momentul in care acestea o sa fie apelate o sa arunce o exceptie de tip NotSupportedException.
Daca ati lucrat cu API-ul de Team Foundation, ati putut observa ca exista deja o implementare pentru acesta colecție. La fel si in API-ul de la Office 2007.
Daca nu lucram cu API-uri care au deja implementari a unui dictionar read-only, putem sa ne definim noi propia implementare. Tot ce trebuie sa facem este sa implementam interfata IDictionary care sa accepte in constructor un dictionar sau o colectie de elemente . Toate metodele care permit adaugare, modificare sau editare de elemente din dictionar nu trebuie implementate.
O alta varianta este sa va definiti si o interfata de tip IReadOnlyDictionary, care sa permita doar acces la date.
Mai jos puteti sa gasiti o implementare a unui ReadOnlyDictionary, implementand direct interfata IDictionary.

  public class ReadOnlyDictionary<TKey, TValue> : IDictionary<TKey, TValue>
    {
        private const string NotsupportedExceptionMessage = "This dictionary is read-only";

        private readonly IDictionary<TKey, TValue> _dictionary;

        public ReadOnlyDictionary(IDictionary<TKey, TValue> dictionary)
        {
            _dictionary = dictionary;
        }

        public void Add(TKey key, TValue value)
        {
            throw new NotSupportedException(NotsupportedExceptionMessage);
        }

        public bool ContainsKey(TKey key)
        {
            return _dictionary.ContainsKey(key);
        }

        public ICollection<TKey> Keys
        {
            get { return _dictionary.Keys; }
        }

        public bool TryGetValue(TKey key, out TValue value)
        {
            return _dictionary.TryGetValue(key, out value);
        }       

        public bool Contains(KeyValuePair<TKey, TValue> item)
        {
            return _dictionary.Contains(item);
        }

        public void CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex)
        {
            _dictionary.CopyTo(array, arrayIndex);
        }

        public int Count
        {
            get { return _dictionary.Count; }
        }

        public bool IsReadOnly
        {
            get { return true; }
        }

        public TValue this[TKey key]
        {
            get
            {
                return _dictionary[key];
            }
            set
            {
                throw new NotSupportedException(NotsupportedExceptionMessage);
            }
        }

        public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
        {
            return _dictionary.GetEnumerator();
        }

        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
        {
            return (_dictionary as System.Collections.IEnumerable).GetEnumerator();
        }

        public bool Remove(TKey key)
        {
            throw new NotSupportedException(NotsupportedExceptionMessage);
        }

        public void Add(KeyValuePair<TKey, TValue> item)
        {
            throw new NotSupportedException(NotsupportedExceptionMessage);
        }

        public void Clear()
        {
            throw new NotSupportedException(NotsupportedExceptionMessage);
        }

        public bool Remove(KeyValuePair<TKey, TValue> item)
        {
            throw new NotSupportedException(NotsupportedExceptionMessage);
        }

        public ICollection<TValue> Values
        {
            get {  throw new NotSupportedException(NotsupportedExceptionMessage); }
        }
    }

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What Is Clean Code?

Reciteam "Clean Code" zilele astea și am dat peste definițiile date de către mai multi programatori a cea ce înseamna un cod curat. Mai jos găsiți aceste citate:

I like my code to be elegant and efficient. The logic should be straightforward to make it hard for bugs to hide, the dependencies minimal to ease maintenance, error handling complete according to an articulated strategy, and performance close to optimal so as not to tempt people to make the code messy with unprincipled optimizations. Clean code does one thing well.

Bjarne Stroustrup

Clean code is simple and direct. Clean codereads like well-written prose. Clean code neverobscures the designer’s intent but rather is fullof crisp abstractions and straightforward linesof control.

Grady Booch

Clean code can be read, and enhanced by adeveloper other than its original author. It hasunit and acceptance tests. It has meaningfulnames. It provides one way rather than manyways for doing one thing. It has minimal dependencies,which are explicitly defined, and providesa clear and minimal API. Code should beliterate since depending on the language, not allnecessary information can be expressed clearlyin code alone.

Dave Thomas

I could list all of the qualities that I notice inclean code, but there is one overarching qualitythat leads to all of them. Clean code alwayslooks like it was written by someone who cares.There is nothing obvious that you can do tomake it better. All of those things were thoughtabout by the code’s author, and if you try toimagine improvements, you’re led back towhere you are, sitting in appreciation of thecode someone left for you—code left by someonewho cares deeply about the craft.

Michael Feathers

In recent years I begin, and nearly end, with Beck’srules of simple code. In priority order, simple code:
• Runs all the tests;
• Contains no duplication;
• Expresses all the design ideas that are in thesystem;
• Minimizes the number of entities such as classes,methods, functions, and the like.
Of these, I focus mostly on duplication. When the same thing is done over and over,it’s a sign that there is an idea in our mind that is not well represented in the code. I try tofigure out what it is. Then I try to express that idea more clearly.

Ron Jeffries

You know you are working on clean code when eachroutine you read turns out to be pretty much whatyou expected. You can call it beautiful code whenthe code also makes it look like the language wasmade for the problem.

Ward Cunningham

Care este definiția voastră a "Clean Code"? Sau ce ar trebuii sa conțină un cod ca sa respecte aceasta definiție?

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How to normalize text to English base

Cand avem o aplicatie care este accesata din mai multe tari, poate sa apara o problema cand se pune problema cautarii sau stocarii datelor. Daca avem o adresa scrisa in limba romana de exemplu o sa avem caractere precum 'â', 'ț', ... dar cand un utilizator dintr-o alta tara o sa caute o anumita adresa de exemplu vrem sa normalizam textul.
O varianta destul de simpla la aceasta problema este sa normalizam tot textul spre caractere ascii base. In acest caz de exemplu 'ț' o sa devina 't'.
Acest lucru se face destul de simplu folosind metoda Normalize, făcând o descompunere canonica a textului.
string normalizeText = sourceText.Normalize(Normalize.FormD);
Trebuie sa avem grija la unele semne de legatura precum 'ß', pentru care trebuie sa facem manual transformarea( dacă dorim).
Mai jos gasiti implementarea pe care eu o propun:

private static readonly char[] SplitChars;
private static readonly Dictionary<char, char> SpecialChars;
static Constructor()
        {
            SpecialChars = new Dictionary<char, char>();
            SpecialChars.Add('ß', 's');

            SplitChars = new[] { ' ', '"', '\'', '`', '"', '-', ',', '.' };
        }
private string ConvertToBaseASCII(string text)
        {
            var normalize = text
                                .ToLowerInvariant()
                                .Normalize(NormalizationForm.FormD)
                                .Split(SplitChars, StringSplitOptions.RemoveEmptyEntries);
            StringBuilder sb = new StringBuilder();

            foreach (string item in normalize)
            {
                foreach (var c in item)
                {
                    UnicodeCategory unicodeCategory = CharUnicodeInfo.GetUnicodeCategory(c);
                    if (SpecialChars.Keys.Contains(c))
                    {
                        sb.Append(SpecialChars[c]);
                        continue;
                    }
                    if (unicodeCategory != UnicodeCategory.NonSpacingMark)
                    {
                        sb.Append(c);
                    }
                }
            }

            return sb.ToString().Normalize(NormalizationForm.FormC);
        }

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Timer - run action at a specific time interval

Nu odată am întâlnit requirement-uri la o aplicație de genul:
Se da un proces ce trebuie executat la un anumit interval de timp. Un proces se poate executa doar dacă a trecut un anumit interval de timp de la terminarea ultimei procesări.
Exista mai multe soluții la aceasta problema. Thread-uri, timer, sleep and so on. Pentru a vedea cum se folosește un timer click aici.
Soluția care mi-e mi s-a părut cat de cat curata se bazează pe un timer setat sa ruleze o singura data, iar după fiecare procesare acesta este pornit din nou.
Trebuie avut grija la următoarele posibile probleme care pot sa apară:
     1. Când se face Start, Stop la timer trebuie avut grija ca suntem într-un mediu multi-thread, din aceasta cauza trebuie sa ne asiguram ca avem un mecanism de lock-ing.
     2. La fiecare execuție a callback-ului pe care timer-ul îl arunca trebuie verificat dacă timer-ul nu a fost oprit deja prin intermediul altui thread.
     3. In callback trebuie sa avem grija sa avem grija sa prindem excepțiile care pot sa apară din codul nostru înainte sa dam drumul la timer. Altfel ne putem trezi ca după o eroare timer-ul nu mai funcționează deși noi ne-am aștepta sa ruleze în continuare.
Mai jos găsiți implementarea pe care eu o propun:

public class CustomTimer
    {
        private readonly Timer _timer;
        private readonly object _timerPadLock = new object();
        private bool _timerStarted;

        private readonly int _timeInterval;
        private readonly Action _action;


        public CustomTimer(TimeSpan timeInterval,Action action)
        {
            _timeInterval = Convert.ToInt32(timeInterval.TotalMilliseconds);
            _action = action;

            _timer = new Timer(
                TimerCallback,
                _timer,
                Timeout.Infinite,   // When set to infinite the timer is not started automatically.
                Timeout.Infinite);
        }

        public void Start()
        {
            if (!_timerStarted)
            {
                lock (_timerPadLock)
                {
                    if (!_timerStarted)
                    {
                        _timerStarted = true;
                        RunTimer();
                    }
                }
            }
        }

        public void Stop()
        {
            lock (_timerPadLock)
            {
                _timerStarted = false;
            }

        }

        private void TimerCallback(object state)
        {
            if (!_timerStarted)
            {
                return;
            }

            try
            {
                // Invoke custom action.
                _action.Invoke();
            }
            catch (Exception ex)
            {
                // Exception handling
            }


            RunTimer();
        }

        private void RunTimer()
        {
            _timer.Change(_timeInterval, Timeout.Infinite);
        }
    }

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Enterprise mLearning Predictions for 2012

Here on the last day of the year, I offer my predications for the big and shaping trends we’ll see in the enterprise mobile learning space for 2012.  As in the past, this year’s list includes predictions across a gamut of new technologies, consumer/buyer trends plus a few anticipated seismic shifts in the world of business that should collectively reshape the landscape for the adoption and accelerated growth of mobile learning for businesses.

So, in no certain order, here are my predictions…

1. Mobile Learning Goes Mainstream. Or perhaps this is more a case of the classic “frog in boiling water” scenario. Whatever it is, this one is music to my ears after many years of toiling away to make mLearning a reality for the enterprise. The acceptance of mobile learning within the business community probably won’t happen with much fanfare, it will just happen and be accepted as a “norm” wherein the market no longer asks “should we offer learning to our employees (or partners or customers) via mobile device?” and will simply state “we need to offer learning to our workers via their omnipresent mobiles!” The reasons will be plentiful but largely driven by better/cheaper/more ubiquitous technologies and everyone’s acceptance of the fact we all use our phones (tablets, et al) to improve both personal and business communications and to be more productive.

2. Access Points Diversify.  There will be more types of devices and ways to connect with our mobile learning world in 2012. And I am not just talking about the classic iOS vs. Android vs. other argument but the fact that different classes of hardware will start to get into our learning mix too. By next December, the average corporate learner will likely have a capable smartphone and their desktop/laptop PLUS a media tablet and/or eBook reader and perhaps even a smart TV back at home that is web-connected and runs apps. The ability to move seamlessly from one device experience to another will be critical with complete synchronization of our learning progress, status, achievements, etc. no matter where or when we choose/need to learn.

3. Mobile Web vs. Mobile App Debate Intensifies. Is enterprise mobile learning best delivered via native mobile apps or using mobile web apps? I agree the technologies to create, deploy and manage HTML5-based mobile web apps will greatly improve in 2012 but I don't feel they will mature to the point they can replace all native apps – at least in most of the primary enterprise use cases for learning that’s managed and tracked. The many advantages of mobile web apps – like cross platform OS support for iOS, Android and others – will still be mitigated in key areas like security, off-line storage, sync updates, access to device features like cameras (although this is improving in the spec) plus critical infosec concerns like SSO support when disconnected and remote wipe capabilities that just don’t work in mobile web apps yet. We do sense that mobile web apps will start to take their rightful place when looking to support an organization’s external learners (e.g., partners, customers) where ease of install/access are paramount and the required features can be limited to what’s essential instead of everything that’s required by IT, security and management.  We also think hybrid apps that mix the best of native apps and mobile web apps will have a bigger impact on enterprise mobile learning thoroughout 2012 than just pure mobile web apps for that same market.

4. Flash Falters, HTML5 & ePUBs Gain in Popularity. 2012 will be a pivotal year in the way enterprises must think about designing, producing, delivering and managing their content strategies, and mobility strategies will alter many of our current tool kit and business process choices.  Adobe’s move to stop developing Flash Player plug-ins for mobile web browsers set a BIG BALL in motion that quelled the desire for many Instructional Designers to use pure Flash or popular rapid development tools outputting Flash-based content as their unified content delivery strategy.  Part of this shift was driven by the fact that Flash-based content actually didn’t perform/behave well on most Flash-enabled handsets and tablets especially when the content was local rather than on a server. Much has been said and written about the next wave of HTML5-based authoring tools or updates that will transform yesterday’s authoring tools into tomorrow’s more flexible and functional authoring systems and I suspect we’ll have nice working versions of the top five offerings able to create content that’s both desktop and mobile device friendly by mid year with commercial ready offerings from Adobe, Articulate and a host of others.

I also think many teams will begin to rethink their content creation and delivery options resulting in new ways to chuck up or package content that’s friendly to both online and mobile consumption scenarios. One trend is to move away from monolithic, structured 20 to 30 minute courses that worked fine online via a PC towards the notion of shorter, standalone learning objects that can be more easily discovered, accessed and consumed at the time of need from any device/app.  Another counter-balanced trend gaining momentum will be the use of eBook style delivery formats that make it easier to produce and manage long-form content that is far more feature rich than static PDF files. Growing interest in the ePUB content formats, especially media-friendly ePUB-3s, will allow learners to gain more from and interact better with the content packages themselves and enable cool functionality like highlighting, like better indexing/threading and both personal and shared note taking all with the same level of access control and tracking that’s generally only found today with an online eLearning course.     

5. Gamification Accelerates mLearning Adoption.  Once everyone has the right devices and organizations accept the mandate to provide training, performance support and business communications via mobile, what will compel learners to participate and keep them engaged when there are so many distractions like Facebook, Twitter, Farmville and mobile shopping? Gamification seems to be a likely answer to that question. Not that companies need to even create “games” per se; rather, the trend will be towards gamifying our standard formal learning actions and informal social interactions through the addition of point systems, achievement leveling/scaling, overall leader boards, badging systems and tangible reward/incentives. Increased awareness of who’s ahead and how can others beat them to the finish line will drive learner engagement and overall organizational behavior and mobile access to these learning materials and communities makes it easier to participate and stay connected whenever the mood suits us.

6. Fewer but More Capable Tablets. I suspect the annual Consumer Electronics Show (“CES”) event in Las Vegas next week will have far fewer tech OEMs wading into the tablet pool as compared with January 2011. Apple’s iPad will continue to be the market leader in 2012 though a collection of tablet devices based on Android (in older Honeycomb to newer Ice Cream Sandwich flavors), Microsoft Windows 8 and possibly even RIM’s PlayBook 2.0 OS will continue to eat away at Apple’s market share as organizations seek to take advantage of the tablets for media consumption, user-generated content creation and in situ selling supported. Interest in using tablets for business purposes comes across business sectors large and small alike too and we see the broader trend of tablets replacing laptops in many instances and even becoming shared devices in certain use cases (e.g., retail sales, in field tech trucks, departmental loaners) but requiring enterprise level controls and security too. 

7. Cool Mobile Tech Sparks Learning Innovations. The latest mobile devices support a wide array of new features that will ignite some nifty innovations in the learning space throughout 2012. As people and companies replace their older BlackBerries, iPhones and Android devices, their new equipment will sport cool next-gen functions like dual core processors making big media and big data easier to manage on our smaller devices. We will benefit from faster data speeds using LTE (“long term evolution”) or true 4G radios enabling quicker access to high value content as well as video access to our experts and web conferencing access to scheduled ILT events. And more advanced operating systems combined with embedded chips will provide support for new forms of proximity computing using Near Field Communication (“NFC”) thus allowing new kinds of location-based services for learning. I feel the positive effects of the aforementioned evolutions will be more pronounced than similar advances in areas like augmented reality that will remain costly to design, produce and manage.  

8. Market Consolidations Continue/Accelerate.  The big will continue to eat the small as larger vendors seek to increase their market appeal to both customers and investors. According to Bersin & Associates, 2011 already saw several of the tier one Talent Management vendors actively engaged in expanding their market reach and the portfolio offerings through strategic acquisitions and mergers and these moves make the resulting companies far more attractive acquisitions to the larger enterprise software whales that rule their respective oceans. SAP’s planned takeover of SuccessFactors and Oracle’s move on RightNow (approved this week) all are harbingers of more market consolidation as larger companies look to flesh out their cloud, mobile and social strategies. 

Summary. That is what I see in my crystal ball. It should prove to be an interesting year for all of us involved in the training & development and technology spaces and I, for one, look forward to seeing how these cited advances and many others we can’t foresee today will influence how we all interact and learn.

Happy New Year 2012!

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