VB.NET and The Microsoft .NET Initiative

1
VB.NET andThe Microsoft .NET Initiative

• Michael B. Spring
• Department of Information Science and
  Telecommunications
• University of Pittsburgh
• spring_at_imap.pitt.edu
• http//www.sis.pitt.edu/spring

2
Context

• VB.NET can only be understood as one small part
  of a much larger system
• VB has a long tradition of making coding
  extremely easy by embedding functionality in
  components. This tradition continues in VB.NET
• VB.NET also provides a language and development
  environment that is vastly improved error
  messages, try-catch block, true classes.
• Finally VB.NET makes socket and DBMS connections
  very easy

3
.NET in a Nutshell

• Imagine an environment within which you can write
  a few hundred lines of perfect client code by
  clicking a few buttons.
• Imagine an environment within which devices of
  all sorts know how to connect to other devices
  in the environment.
• Imagine an environment within which all the
  services are prepared for a connection through
  some kind of extensible clearinghouse.

4
Overview

• Context
• The technology
• Historically
• Retooled
• The pieces of .NET
• For the end user
• For the system administrator
• For the programmer

5
Context

• The Web is accepted as THE environment within
  which future technologies will be developed.
• The servers are in place
• People know how to use browsers
• Existing tools and infrastructure to support
  distributed services are being redesigned.
• Servers that are web ready
• IDEs that ease the development process using
  object oriented approaches
• Applications that are service aware

6
The General Strategy

• Web servers have had the ability to run programs
  that produce output for years. (CGI programs have
  historically produced dynamic web pages.) This
  continues with
• Servlets
• Server-side includes
• ASP, JSP, and ASP.NET
• Browsers have had the ability to run programs for
  years. (Applets and the Java Runtime Environment
  JRE, started this process.) This continues
  with
• Plug-ins
• Scripting languages
• Downloaded executables

7
Microsoft and the Web

• Microsoft views the next generation web as a
  challenge to its control of the desktop
• Microsofts response .NET is one approach to
  developing a distributed computing environment
• Microsoft is making all of their servers web
  compliant
• Microsoft is upgrading their development software
  to include support for web services via wizards
• Microsoft plans to promote this new environment
  via killer applications e.g. Office and Xbox

8
The Original Technology

• Distributed computing, based on a client server
  model, has been with us for years.
• The programming of distributed applications
  required extensive coding for even simple tasks.
• The transmission and reception of messages had to
  be monitored and manually controlled.
• Packet sequencing
• Lost packet management
• Data conversion across platforms had to be
  managed.
• The location of servers had to be known in
  advance.

9
The Evolution of the Technology

• The programming of distributed applications was
  made simpler by several developments
• The use of TCP/IP stacks made connection
  management easier
• The use of marshalling tools (XDR, ASN.1) made
  the movement of data between platforms easier.
• The use of higher level APIs (RPC and RMI) made
  the design task easier.
• The use of registration (portmapper, the
  registry) to locate objects
• The use of component transaction monitors (CORBA,
  DCOM) to manage processes.

10
The New Technology

• The next generation web .NET is simply a form
  of distributed services. The environment allows
  for services that are
• Registered and discovered asynchronously
• Allocated at run time dynamic late binding
• Highly modular allowing for n-tiered
  architectures
• May be peer-to-peer or client server
• Instant messaging (AOL IM) and file sharing
  services (Gnutella) are examples of peer-to-peer
  services.

11
Infrastructure

• Abstract syntax
• A device independent form for data
• Component transaction monitors
• These are processes that manage other processes
  e.g. keeping a process in memory rather than
  restarting it each time.
• Distributed directory services
• A way of finding things by reference
• Security and authentication
• A way of providing both encryption and
  non-repudiation

12
Abstract Syntax XML

• Data interchange needs to be device independent.
  XML serves this purpose.
• XML is also used as the base language for
• The Universal Description, Discovery, and
  Integration (UDDI) protocol. The UDDI protocol
  is used to advertise, find, and combine services.
• The Web Services Description Language (WSDL)
  which allows web services to be defined or
  invoked.
• The Simple Object Access Protocol (SOAP) which is
  the mens used to transmit requests and responses
  including WSDL or UDDI requests and responses.

13
CTM Infrastructure

• CGI initially started a new process every time a
  script was called. This was expensive.
• First CORBA and then DCOM provided models for
  accessing a process (service) running on a remote
  machine.
• Processes that provide this kind of service are
  called Component Transaction Monitors (CTMs).
  CTMs manage processes. They
• Maintain heavily used processes in memory
• Provide some form of indirect connection.
• Provide wrap around services such as transaction
  rollback, security, and authentication
• Currently Passport is the main .NET CTM service

14
Directory Infrastructure

• The directories allow resources to describe and
  advertise themselves so as to be discovered.
• They are distributed and object oriented based on
  the X.500 Directory Service or Lightweight
  Directory Access Protocols (LDAP).
• UDDI is the protocol for advertising and
  discovery.
• WSDL is the protocol for description

15
Security and Authentication

• CTMs will implement secure pipes of various types
  between monitors to allow transactions that begin
  and end behind firewalls to move across the
  unprotected internet.
• Certificates will be used as the basis for the
  development of a web of trust that will allow for
  authentication and non-repudiation
• The Passport Service is the Microsoft service for
  authentication

16
Finding a Registered Service
Directory
discovery
registration
Browser
UDDI SOAP HTTP
17
Using Known Hidden Services
WSDL/SOAP HTTP
Browser
Server
18
.NET

• .NET is built by extending and creating new tools
  and services in three areas
• A set of servers both modified existing (SQL
  and Exchange) and new (BizTalk)
• A set of tools the wizards in VB and C are
  extended to encompass web services
• New foundation services advertising,
  notification, and security (Passport) that are a
  part of the CTM.

19
.NET for the User

• Microsoft will help users see how this new
  environment will work by building new devices and
  services
• New devices that consume services
• Xbox
• Tablet PC
• Smart phone
• User experiences that promote the new environment
• Office will be .NET sensitive
• Microsoft Project will be .NET sensitive
• XP will be .NET sensitive

20
.NET for the Sys Admin

• Most of the Microsoft servers are being optimized
  to act as or interact with CTMs
• Windows Client OS
• XP clients are service enabled as device
  coordinators
• Server OSs
• 2000 Normal, Advanced, and Datacenter
• .NET services include specialized functionality
  for databases, internet and intranet services,
  management services, messaging/collaboration,
  business solutions and portable devices

21
.NET for the Sys Admin

• Database
• SQL Server
• Internet and Intranet
• BizTalk and Commerce Server
• Content Management Server
• Security and Accelleration Server
• Sharepoint Portal Server
• Mobile Information Server

22
.NET for the Sys Admin

• Messaging and Collaboration
• Exchange Conferencing Server
• Content Management Server
• SharePoint Portal Server
• Management Tools
• Application Center
• Operations Manager
• Services for Unix and Netware

23
.NET for the Programmer

• Even doing something tiny in a distributed
  environment is hard
• Microsoft solves this problem by hiding this
  complexity in optimized objects with properties
• VB.NET has been referred to as the Javatization
  of Visual Basic
• VB is now compiled to byte codes for efficiency
  (CLR)
• There are a set of class libraries, just like
  Java
• VB has become more object oriented

24
2-Tier Programming

• The design challenge in distributed processing is
  the allocation of responsibility
• In simple two tier systems
• The client should be responsible for presentation
• The server should be responsible for the
  centralized or shared components
• This can lead to server overload as 1000s of
  users vie for the attention of the server

25
3-Tier Programming

• 3 tier systems help to offload the strain on the
  server by placing the majority of the processing
  on the server in a middle business logic layer
• The client is responsible for presentation
• The middle layer is responsible for the logic
• The data layer is responsible only for the data
  store
• This helps with server overload by restricting
  the contention to access to data this has to be
  one machine. The middle layer can be allocated
  to mutltiple machines

26
N-Tier Programming

• In reality, the client can be communicating
  simultaneously with multiple servers, which can
  in turn offload parts of their work to numerous
  background servers
• This provides significant flexibility in the
  balancing of loads and clarity of coding

27
The Complex Made Simple(1)

• To build a server, you need to
• Bind a port to a socket
• Start the socket listening
• Fork a new process when a connection is made
• Translate incoming messages to the native format
• Invoke the needed function
• Marshall the returns of a structure
• Write the data back to the socket
• In VB.NET, you select Build web Service wizard,
  answer yes, type ltWebMethod()gt in front of the
  function, and press Start.

28
The Complex Made Simple(2)

• If your server accesses a DBMS, you need to
• Open a connection to the DBMS
• Open a given database
• Formulate the needed SQL statement
• Submit the statement
• If it returns data, the data needs to be
  organized and stepped through with appropriate
  data type translations
• With VB.NET open Data Form Wizard, set the
  properties, and call a predefined method on the
  object created

29
The Complex Made Simple(3)

• To access a server in a program, you need to
• Allocate a socket
• Open a connection to a machine and port via the
  socket
• Build a request using the wire format
• Send the message, identifying the needed function
• Unmarshall the data returned via a structure
• Take action on the data
• With a browser, simply type the URL directory
  location service name of the service created.
• With VB.NET, use the add web reference wizard and
  build the dialog.

30
Conclusions

• .NET is Microsofts approach to component based
  distributed computing.
• The focus of their effort is three fold
• They are rewriting all of their components
  servers so that they are ready for contact
• They are revamping their coding environments such
  that clients (VB.NET) and server side glue
  (ASP.NET) are easy to write.
• They are developing applications of their own
  (Office, Xbox, etc) that demonstrate this new
  approach.