Tech-Ed Notes

I’m slowly getting through some good sessions from the Tech-Ed (US) DVD set, and making a few notes on the way (appologies to speakers if I’ve butchered their ides):

Ingo Rammer - Scalability/Connected Systems Troubleshooting Talk - CSI 448

• network profiling - DO THIS FIRST
• Tools - ethereal (my fave), tcptrace, fiddler, proxytrace
• Lessons Learned
    - Interactions: too many or too large
    - Latency vs. Bandwidth
     Bandwidth is improving quicker than latency (latency is constrained by speed of light)
     1200 BPS modem to download 2 GB- “it’s quicker to walk”
•  SQL Profiling - do this second
• Look for an appropriate number of statements given the “work“ that needs to be done. Be wary of generated SQL and foreaching -> update over items in datasets
• CLR Proflier - once you’ve done your network profiling and SQL profling
   - tools like the CLR profiler (and Compuware, ANTS Profiler etc) can only show you “in process” optimizations.

 Random Suggestion: Learn and understand NLB in server 2003 - you won’t be able to cluster unless you design and test for this up front.

 HTTP-isms

• set HTTP Connection limit (to get over the 2 connections to a singler server per client HTTP restriction) http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpgenref/html/gngrfconnectionmanagementelement.asp 
• on the web service proxy set proxy.PreAuthenticate = true; for HTTP basic auth (reduces 1 round trip to the server)
• use “authenticated connection sharing” if using Windows Integrated Security - for windows auth set proxy.UnsafeAuthenticatedConnectionSharing = true; (but you need to cache the connection by a key) so also set proxy.ConnectionGroupName = “key” (or “GroupName” or whatever) so you can connect as the “right” connection.
• turn off custom errors in IIS if your clients are all going to be web services esp for 401 (save some bandwidth)

Tim Ewald - Web Services Tips & Tricks - CSI353

4 things that ASMX “plumbing” does for you (I liked this overview)

1. automatic, extensible WSDL generation
2. serialization/deserialization
3. dispatch messages to [WebMethod]s
4. hooks for message interception

Tips

• Design your contract carefully (code first vs. schema first)
• it is often better to handle messages as a single parameter -> closer to messaging
• SoapParameterStyle.Bare attribute (in code) = … if part name = “parameters” then the plumbing will “rip apart” your message and turn it into a serise of parameters. Otherwise it uses the (better) bare style.
• XML Serializer and polymorphism - you need to annotate the base class as shown below (employee is the base)
   
   [XmlRoot(Namespace=“urn:mindreef-com:people”)]
   [XmlInclude(typeof(Employee))]
   public class Person {  
    public string Name;  
    public int Age;
   }
   
   [XmlRoot(Namespace=“urn:mindreef-com:people”)]
   public class Employee {  
    public double Salary;
   }
• Serialization Problems
    - default values - tweak in the serializer - if you have a field called foo and you want to know if foo was sent (to get around the “missing value” problem) we create a [XmlIgnore] property called fooSpecified (case-sensitive) and the run-time will populate that for us.
    - in whidbey use nullable types
• Get Access to Raw XML
    - change argument type to “xmlelement” (but can nolonger generate a meaningful contract)
    - bad if you have big incoming messages (the DOM is heavy-weight)
    - you can implement IXmlSerializable (in framework 2.0) to get a stream instead of an element
    - also XML Schema Provider in framework 2.0
• Run WSDL.exe form the commandline (vs. Add Web Reference, which makes too many choices for you) 
• WSDL.exe + shared types, schema importer extensions etc in whidbey
• Use a facade to insulate the client or service proxies from the “real” code.