Wednesday, February 23, 2005

What great .NET developers ought to know

Excerpted from

What Great .NET Developers Ought To Know

Everyone who writes code

  • Describe the difference between a Thread and a Process?
  • What is a Windows Service and how does its lifecycle differ from a "standard" EXE?
  • What is the maximum amount of memory any single process on Windows can address? Is this different than the maximum virtual memory for the system? How would this affect a system design?
  • What is the difference between an EXE and a DLL?
  • What is strong-typing versus weak-typing? Which is preferred? Why?
  • Corillian's product is a "Component Container." Name at least 3 component containers that ship now with the Windows Server Family.
  • What is a PID? How is it useful when troubleshooting a system?
  • How many processes can listen on a single TCP/IP port?
  • What is the GAC? What problem does it solve?

Mid-Level .NET Developer

  • Describe the difference between Interface-oriented, Object-oriented and Aspect-oriented programming.
  • Describe what an Interface is and how it’s different from a Class.
  • What is Reflection?
  • What is the difference between XML Web Services using ASMX and .NET Remoting using SOAP?
  • Are the type system represented by XmlSchema and the CLS isomorphic?
  • Conceptually, what is the difference between early-binding and late-binding?
  • Is using Assembly.Load a static reference or dynamic reference?
  • When would using Assembly.LoadFrom or Assembly.LoadFile be appropriate?
  • What is an Asssembly Qualified Name? Is it a filename? How is it different?
  • Is this valid? Assembly.Load("foo.dll");
  • How is a strongly-named assembly different from one that isn’t strongly-named?
  • Can DateTimes be null?
  • What is the JIT? What is NGEN? What are limitations and benefits of each?
  • How does the generational garbage collector in the .NET CLR manage object lifetime? What is non-deterministic finalization?
  • What is the difference between Finalize() and Dispose()?
  • How is the using() pattern useful? What is IDisposable? How does it support deterministic finalization?
  • What does this useful command line do? tasklist /m "mscor*"
  • What is the difference between in-proc and out-of-proc?
  • What technology enables out-of-proc communication in .NET?
  • When you’re running a component within ASP.NET, what process is it running within on Windows XP? Windows 2000? Windows 2003?

Senior Developers/Architects

  • What’s wrong with a line like this? DateTime.Parse(myString);
  • What are PDBs? Where must they be located for debugging to work?
  • What is cyclomatic complexity and why is it important?
  • Write a standard lock() plus “double check” to create a critical section around a variable access.
  • What is FullTrust? Do GAC’ed assemblies have FullTrust?
  • What benefit does your code receive if you decorate it with attributes demanding specific Security permissions?
  • What does this do? gacutil /l | find /i "Corillian"
  • What does this do? sn -t foo.dll
  • What ports must be open for DCOM over a firewall? What is the purpose of Port 135?
  • Contrast OOP and SOA. What are tenets of each?
  • How does the XmlSerializer work? What ACL permissions does a process using it require?
  • Why is catch(Exception) almost always a bad idea?
  • What is the difference between Debug.Write and Trace.Write? When should each be used?
  • What is the difference between a Debug and Release build? Is there a significant speed difference? Why or why not?
  • Does JITting occur per-assembly or per-method? How does this affect the working set?
  • Contrast the use of an abstract base class against an interface?
  • What is the difference between a.Equals(b) and a == b?
  • In the context of a comparison, what is object identity versus object equivalence?
  • How would one do a deep copy in .NET?
  • Explain current thinking around IClonable.
  • What is boxing?
  • Is string a value type or a reference type?
  • What is the significance of the "PropertySpecified" pattern used by the XmlSerializer? What problem does it attempt to solve?
  • Why are out parameters a bad idea in .NET? Are they?
  • Can attributes be placed on specific parameters to a method? Why is this useful?

C# Component Developers

  • Juxtapose the use of override with new. What is shadowing?
  • Explain the use of virtual, sealed, override, and abstract.
  • Explain the importance and use of each component of this string: Foo.Bar, Version=, Culture=neutral, PublicKeyToken=593777ae2d274679d
  • Explain the differences between public, protected, private and internal.
  • What benefit do you get from using a Primary Interop Assembly (PIA)?
  • By what mechanism does NUnit know what methods to test?
  • What is the difference between: catch(Exception e){throw e;} and catch(Exception e){throw;}
  • What is the difference between typeof(foo) and myFoo.GetType()?
  • Explain what’s happening in the first constructor: public class c{ public c(string a) : this() {;}; public c() {;} } How is this construct useful?
  • What is this? Can this be used within a static method?
Developers using XML
  • What is the purpose of XML Namespaces?
  • When is the DOM appropriate for use? When is it not? Are there size limitations?
  • What is the WS-I Basic Profile and why is it important?
  • Write a small XML document that uses a default namespace and a qualified (prefixed) namespace. Include elements from both namespace.
  • What is the one fundamental difference between Elements and Attributes?
  • What is the difference between Well-Formed XML and Valid XML?
  • How would you validate XML using .NET?
  • Why is this almost always a bad idea? When is it a good idea? myXmlDocument.SelectNodes("//mynode");
  • Describe the difference between pull-style parsers (XmlReader) and eventing-readers (Sax)
  • What is the difference between XPathDocument and XmlDocument? Describe situations where one should be used over the other.
  • What is the difference between an XML "Fragment" and an XML "Document."
  • What does it meant to say “the canonical” form of XML?
  • Why is the XML InfoSet specification different from the Xml DOM? What does the InfoSet attempt to solve?
  • Contrast DTDs versus XSDs. What are their similarities and differences? Which is preferred and why?
  • Does System.Xml support DTDs? How?
  • Can any XML Schema be represented as an object graph? Vice versa?

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