CS795/895: Introduction

1
CS795/895 Introduction

• Summer 2006

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Topics

• Distributed Systems
• Availability
• Performance
• Web Services
• Security
• Authentication
• Authorization
• Confidentiality

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Distributed Systems

• Geographically Distributed
• Replication is the primary means to provide high
  availability and performance
• Replication/failure transparency are desired by
  distributed applications
• Protocols to communicate between distant
  processes are important SOAP

4
Web Services

• Service offered over the web
• It facilitates request-reply paradigm using
  message exchange
• Uses
• HTTP (Hypertext Transport Protocol)
• SOAP (Simple Object Access Protocol)
• UDDI (Universal Description, Discovery and
  Integration)
• WS-POLICY (Web Services Policy)

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.Net Framework

• Write the source code (e.g., using C)
• Compile using a C Compiler (csc.exe).
• The compiler converts the source code into an
  Intermediate Language, much like byte codes in
  Java. This is managed code (exe or DLL) .
• The compiled file unit is executed using the C
  Interpreter. Upon execution, the code is checked
  for type safety. Moreover, the Just In Time (JIT)
  compiler compiles the unit into Managed Native
  Code and finally Common Language Runtime (CLR)
  produces the final output.

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CLR Common Language Runtime

• Runtime environment of .Net Framework, manages
  execution of code, and provides different
  services
• CLR contains CTS (common type system), CLS (a
  subset of CTS to be supported by all .Net
  languages), CIL (Common intermediate language),
  JIT compiler (converts to MSIL (in assemblies) to
  executable native code)
• Managed code IL codes along with metadata files
  .exe or dll

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C (C Sharp)

• Improved version of C and Java
• It is type-safe
• In .Net use Projects/Windows application C to
  create and run C programs.
• using System
• namespace Helloworld
• /// ltsummarygt
• /// Summary description for Class1.
• /// lt/summarygt
• class Class1
• /// ltsummarygt
• /// The main entry point for the application.
• /// lt/summarygt
• static void Main(string args)
• Console.Write("What is your name? ")

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ADO.Net

• Provides data access tools for web applications
• Seamless interoperability with XML
• Uses objects such as Connection, Command,
  DataSets, DataReaders, DataSetCommands
• Use SQLConnection for MSQL server and
  ADOConnection via OLEDB provider

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using System using System.Data.SqlClient class
seePubs static void Main () SqlConnection
conn new SqlConnection ("servernebula.cs.od
u.edudatabasepubsUser

IDcwildpasswordwildcs2004") try
conn.Open () SqlCommand cmd new
SqlCommand ("select from titles",
conn) SqlDataReader reader
cmd.ExecuteReader () while (reader.Read
()) Console.WriteLine (reader"title")
catch (SqlException ex) Console.WriteLine
(ex.Message) finally conn.Close
()
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.Net Security Topics

• Threat models
• Storing secrets
• Securing Database access
• ASP.Net security framework
• .Net Cryptography
• Windows authentication
• .Net Passport
• Forms authentication
• Implementing Authorization
• Code access security
• Web services security
• Impersonation