Good Morning folks,

Today I read about streams and files, and as usual I provide my notes as a summary. enjoy !

Textfiles

• To read a textfile, we can use TextReader or StreamReader Class
• To write a textfile, we can use TextWriter or StreamWriter Class
• StreamReader derives from TextReader
• Usually you use File.OpenText or StreamReader Constructor
• Typically we use ReadLine or ReadToEnd Methods to read data
• Dont forget to call Close on the Reader or Writer after finished reading or writing
• To ensure, that no data is left in the buffer while keeping the file open use the Flush Method

Binary Files

• To read and write binary files, use BinaryReader and BinaryWriter
• Generally serialization is more effective

Strings

• Use StringWriter to write data to StringBuilder
• Not used very often, only in special scenarios

MemoryStream

• To create a stream in memory
• Commonly used to store data temporarily that will be written to a file eventually
• To Minimize the time a file is locked open, minimizes the potential for conflict
• MemoryStream often is used with a StreamWriter, cause MS itself has only WriteByte/Write, and ReadByte/Read Methods that work with bytes and byte-arrays

BufferedStream

• Is used for custom stream implements
• .NET Stream Classes have a build-in buffering logic, so you normally dont need to use BufferedStream. If you do so its redundant and inefficent

Compressed Streams

• You can only read or write bytes and byte-arrays directly, but you can use StreamWriter and StreamReader
• Use GZipStream Class for GZIP-Compression and DeflatedStream class for Deflated Data Format
• CompressionMode which is part of the constructor indicates simply if you are compressing or decompressing data

Isolated Storage

• Isolated Storage is a private file system
• It requires fewer privileges than writing to filesystem
• IS is isolated by user, application domain and assembly
• Don’t use to store high-value secrets or sensitive data, because its not protected from high-trusted code, unmanaged code or trusted users of the computer
• The access to a file is restricted to the user who created it
• isolation by application domain is optional
• In most case (almost always) you will use the isolation by application-domain
• Classes to work with Isolated Storage (All in System.IO.IsolatedStorage)
  1. IsolatedStorageFile – Management of Isolated Storage Stores (Often Used Methods are .GetUserStoreForAssembly, .GetUserStoreForDomain, .GetStore
  2. IsolatedStorageFileStream – Access to read/write Isolated Storage files
  3. IsolatedStorageException – exception related to Isolated Sotrage
• Code must be granted IsolatedStorageFilePermission

Hi there

We now leave types behind and go to the input/output chapter. I have to say, writing along while learning takes more time then just reading, but i hope it pays out at the end my having more information stuck in my brain ;o)

Drive Enumerating

• Use DriveInfo.GetDrives to get a List of Drives connected to the system
• You get a Collection over which you can loop
• Available Information: AvailableFreeSpace, DriveFormat, DriveType, IsReady, Name, RootDirectory,TotalFreeSpace, TotalSize, VolumeLabel

Files and Folders

• You can browse a folder by using an instance of DirectoyInfo and call .GetFiles or .GetDirectories
• You can create a directory by using an instance of DirectoryInfo and call .Create
• You can check if a directory Exists by DirectoryInfo.Exists
• Static File Operations: File.Create, File.CreateText, File.Copy, File.Move, File.Delete
• Alternative: Use an instance of FileInfo and call .Create, .CreateText, .CopyTo, .MoveTo, .Delete

Filesystem Monitoring

• Use System.IO.FileSystemWatcher (responds to updated, new and renamed files etc)
• FSW works Eventbased (Changed-Event, Create-Event, Delete-Event, Rename-Event etc.) and provides FileSystemEventArgs (except Rename, this provides RenamedEventArgs
• You can configure the Watcher with:
  1. Filter (Filename, you can use wildcards)
  2. NotifyFilter (Defines, what changes causing a notification (One or more): Filename, Size, LastAccess etc)
  3. Path (Folder to be monitored)

Hello everyone!

Today I learn about Type-Conversion and will share my notes with you. Have fun !

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Hello everyone,

a new day, a new learning experience. Today I work on the “Classes” chapter of my exam-preperation and will share the most interesting parts with you.

Inheritance

• Inheritance and Interfaces provide a way to improve a systems consistency
• via Inheritance you can create new classes from existing once
• With inheritance there comes the possibility to use derived classes interchangeably. That is calles polymorphism. You can for example pass an object of type specialobject (Inheriting of object) to a method which excepts an object.

Interfaces

• Interfaces are contract defining required members the new class must provide. For example the IComparable Interface defines a member method called CompareTo. Every class that implements IComparable must implement this Method.
• Commonly used Interfaces: IComparable, IFormattable, IEuatable, ICloneable, IConvertible, IDisposable
• Example Interface:
  
public interface IMyInterface
{
bool DoSomething();
string Message {get; set; }
int MyNumber {get;set;}
}

• “Extract Interface” is a build in Refactoring-Method of Visual Studio

Partial Classes

• A Class-Definintion can be split into different .cs files. This must be declared by using “partial” keyword in class definition (ex. public partial class}

Generics

• With Generics you can define a type and leav some details unspecified. You dont have to specify the type of certain parameters or members, instead you can define them, when using the new type
• Generics will be a bigger part of the exam
• In System.Collections.Generic you can find some Generics like Dictionary, Queue, SortedDictionary or SortedList.
• Advantages: Reduced run-time-errors (More typesafe) and improve performance (avoids boxing and unboxing)
• Example of Definition:
  
  class MyGeneric
  {
  public T t;
  public U u;

  public MyGeneric(T _t, U _u)
{
t = _t;
u = _u;
}
}


• Important: Code needs to compile for every possible usage !
• Comsuming Example:
  
var test = new MyGeneric("hallo",12);

• Constraints for the Types used (T and U in the example above) can be defined.
  
class MyGeneric where T : IDisposable

• You can use Interfaces, Baseclasses,Constructors and Reference of value types as constraints

Events

• object (Event senders) can trigger events when an action takes place (User clicks button, method completed etc.)
• Event Receivers can handle these events when they occure
• A Delegate is a reference (pointer) to a method that itself has no code.
• The Delegates signature must match the signature of the handling method
• Things to do, to create a custom event:
  1. Create Delegate: public delegate void MyEventHandler(object sender, EventArgs e);
  2. Create event: public event MyEventHandler MyEvent;
  3. Fire Event
if (MyEvent != null)
{
// Invoke Delegate
MyEvent(this, new EventArgs());
}

  4. You can create your own EventArgs. Just create a new Class, that inherits from EventArgs.

Attributes

• Attributes describe Methods or Properties. You can get this information by reflection.
• Commonly used attributes for: Security Privileges, capability (ex.Serialization), description (title, copyright…)
• Attribute Types derive from System.Attribute
• Example – AssemblyAttributes in AssemblyInfo.cs : [assembly: AssemblyTitle("title")]
• Declaring capabilities:
  
[Serializable]
class MyClass
{
}

  Without this Attribute, a class is not serializable.
• Declaring Security Requirements
  
[assembly:FileIOPermissionAttribute(SecurityAction.RequestMinimum, Read=@"C:\settings.ini")]
namespace MyNamespace
{
...
}


Type Forwarding

• Move a type from one assembly to another without needing recompile
• TypeForwardedTo – Attribute
• Example:
  
using System.Runtime.CompilerServices;
[assembly:TypeForwardedTo(typeof(TargetLib.MyType))]

• Works only for components referenced by existing applications
• To use Forwarding, do the following:
  1. Add TypeForwardedTo attribute to source assembly
  2. Cut Typedefinition from source and paste to destination
  3. Re-Compile both.

What have I learned ?

I havent used Attributes very often, so it was a good brush-up, and the Type-Forwarding Part was new for me, so I learned something today – Hurray ! )

Next Topic will be “Type Conversion” .. .stay tuned !

Hello everyone !

Hallo zusammen,

ein neuer Anlauf in Richtung Examen und die Entscheidung, die Blogsprache auf Englisch umzustellen, um schlichtweg mehr Leser anzusprechen. Ich hoffe, es stört nicht zu sehr )

During todays power-cut (don’t know what happened, just no electricity for half an hour) I decided to continue my journey toward Microsoft exam 70-735, the first step to become MCPD.

I will post a summary of any chapter I work through, therefore its not exactly for beginners, more like a little learning help for me and hopefully other people reading it. By the way, my language of choice is C#, so this is what you will read about.

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Objective: Manage data in a .NET Framework application by using .NET Framework system types – Teil 1

Guten Tag,

Heute geht es los mit der Prüfungsvorbereitung. Es sei mir zuerst ein Hinweis auf die Microsoft-eigene Webseite mit vielen wissenswerten Informationen zum Examen gestattet: Infos zum Examen 70-536 auf Microsoft.com

Meine gelernten Inhalte sind als zusammenfassende Stickpunkte verfasst. Wer sich ernsthaft auf die Prüfung vorbereiten will, kommt aber wohl nicht um die Anschaffung eines Buches herum. Ich empfehle folgendes: MCTS Self-Paced Training Kit von Tony Northrup

Microsoft bietet übrigens für begrenzte Zeit wieder das Zweite Chance Angebot. Hierbei bekommt man beim Durchfallen die Wiederholungsprüfung umsonst. Das Ganze gilt bis 30. Juni 2009

Viel Spaß, Sascha Baumann

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Guten Morgen liebe Gemeinde,

Trotz vieler Jahre Erfahrung in der Entwicklung im .NET Framework habe ich eine offizielle Zertifizierung lange vor mir her geschoben. Ich denke das geht vielen so, die der täglichen Arbeit den Vorrang geben, und sich in ihrer knappen Freizeit nicht auch noch mit Programmierung beschäftigen wollen – denn schließlich ist eine gute Work/Life Balance sehr kostbar.

Letztendlich habe ich mich doch dazu entschlossen. Zum einen, weil ich immer wieder gerne neue Dinge lerne (und ich bin mir sicher, ich werde im Laufe der Vorbereitung noch das eine oder andere aufschnappen) zum anderen, weil es als Freiberufler wichtiger ist als in der Festanstellung, die eigenen Kenntnisse verbrieft vorliegen zu haben.

Meinen Fortschritt und meine Lerninhalte möchte ich mit euch teilen, und werde deshalb an dieser Stelle wöchentlich über den Fortgang berichten. Wer Lust hat mitzumachen, dem empfehle ich folgendes Buch: MCTS Self-Paced Training Kit von Tony Northrup

Ich kann natürlich keine Garantie dafür übernehmen, dass ein regelmäßiges Lesen meiner Beiträge automatisch zu einer bestandenen Prüfung führt (Genauso wenig wie ich weiß, ob das Schreiben der selbigen in einer bestandenen Prüfung resultiert ;o) ). Aber vielleicht macht es ja Lust, es selbst mal zu versuchen.

Bis spätestens Ende der Woche werde ich den ersten Artikel fertig haben, und hier posten. Stay Tuned …