J2EE and Microsoft 'NET Framework Enterprise Computing

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J2EE and Microsoft .NET Framework Enterprise
Computing

• CS2340

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Administrivia

• TA applications due tomorrow _at_ noon
• http//www.cc.gatech.edu/TA-app
• 12/2 Demo your project!
• 1 pt extra credit
• Send me email to sign up

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What is an Enterprise?

• A large organization that uses computers
• Has existing IT resources
• databases
• applications
• Has large amounts of data
• May have high transaction volumes
• Has complex multi-tier environments

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What is an Enterprise Application?

• Software that supports the purpose of the
  enterprise
• Examples
• Filling orders
• Tracking inventory
• Handling accounts
• Making reservations

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Evolution of Enterprise Software

• 1960s mainframes with punch card entry
• Batch jobs ran at night from punch cards
• Data usually a day behind
• 1970s mainframes with dumb terminal entry
• VSAM filesystem for data store with indexes and
  keys
• 1980s mainframes with personal computer clients
• SQL for access to relational databases
• Some work done locally
• 1990s Client Server
• Cost of supporting client software was high
• Limits on transaction throughput with 2 tiers
• 2000s N-tier with many different client devices
• J2EE, CORBA, and .Net for enterprise applications

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What is hard about Enterprise Software?

• Handling a variety of operating systems,
  databases, and servers
• Handling large numbers of users
• Handling large numbers of transactions
• Providing security
• Keeping the system up
• Allowing for growth
• Allowing for different client devices (browser,
  wireless, applets, applications)
• Connecting to legacy applications

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What is J2EE?

• Java 2 Platform, Enterprise Edition
• A standard architecture for creating, deploying,
  and managing enterprise-level server-side
  software
• J2EEs Goal
• Provide components that make it faster, cheaper,
  and less complex to develop and maintain
  enterprise applications that are
• machine, server, and database independent
• multi-tier
• scalable
• reliable
• secure

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What do we mean by the J2EE?

• Specifications
• Group developed requirements for the J2EE
  platforms
• Server
• Software that runs J2EE applications
• Compatibility Test Suite
• How a platform is tested to verify specification
  compliance
• Reference Implementation
• A sample implementation of the specifications
• Blueprints
• Best practices and guidelines

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Why use the J2EE?

• Use it for applications that
• Are machine, server, and database independent
• So you can move your application to different
  machines, operating systems, and databases
• Are scalable
• Can grow over time
• Require transactions
• Like debiting one account and crediting another
  at the same time
• Are reliable
• Stay up and handle large numbers of users
• Are secure
• Protect sensitive data

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J2EE Primary APIs

• JavaServer Pages (JSPs)
• Dynamic page creation based on client request
• Java Servlets
• Controller for routing client requests to JSP
• Enterprise JavaBeans (EJBs)
• Represent business entities and processes
• JDBC data access API
• Access data in relational databases
• The Java Naming and Directory Interface (JNDI)
• Access enterprise name and directory services
• The Java Transaction API (JTA)
• Handle distributed transactions
• Interface Definition Language (IDL)
• Access CORBA services via IIOP

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What do the APIs do?
JNDI
EJB
EJB
JTA
EJB
HTTP
Servlet
EJB
JDBC
EJB
EJB
JSP
JSP
IDL
HTML or XML
CORBA
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J2EE Secondary APIs

• Java Message Service (JMS)
• Send asynchronous messages
• JavaMail
• Send and receive e-mail
• J2EE Connector Architecture
• Connect to legacy systems
• XML Pack
• Java API for XML Processing (JAXP)
• Parse and transform XML documents
• Java API for XML Messaging (JAXM)
• Send and receive XML messages
• Java API for XML Registries (JAXR)
• Interact with XML Registries (UDDI and ebXML)
• Java API for XML-based RPC (JAX-RPC)
• Remote procedure calls(RPC) with Simple Object
  Access Protocol (SOAP)

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Common Language Runtime (CLR)

• Its a VM (Java-like) on which any (supported)
  language can run.
• Why a VM?
• Memory Protection
• Cross-language
• Support for strong-typing across languages
• Thread support
• Compactness
• Flexibility (Reflection, Meta-programming)
• JIT compilation in the VM
• Stack-based
• 3 generation garbage collector

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Languages in CLR

• Language of choice is C (C-sharp) a Java-like
  language
• No inner classes
• Better type checking
• Other languages will run on CLR, but only within
  the CLR constraints
• Visual Basic, JScript are full fledged CLR
  languages
• For example, only C that is VM-safe will run
• That subset looks much like C
• Under CLR, all languages get object features
• Inheritance used extensively
• Every language gets constructors

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Supported Languages

• Languages targeted to CLR
• APL C
  C COBOL
• Component Pascal Curriculum Eiffel
  Fortran
• Haskell Java Language
  Microsoft JScript Mercury
• Mondrian Oberon Oz
  Pascal
• Perl Python
  RPG Scheme
• Smalltalk Standard ML
  Microsoft Visual Basic

Languages interoperate seamlessly. Can write
part of app in Scheme, part in C and part in
Smalltalk!
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Languages compile to MSIL

• Languages compile to MSIL (Microsoft Intermediate
  Language)
• Also known as bytecodes
• MSIL is shipped in portable executable (PE) units
• Similar to, say, .class files or applets
• Includes meta-data about types
• An application is made up of assemblies

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Reuse

• Tries to get maximum reuse of components/assemblie
  s (like Smalltalk)

We get this in the .NET world via assemblies.
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Assemblies

• In general, a static assembly can consist of four
  elements
• The assembly manifest, which contains assembly
  metadata (required).
• Type metadata.
• Microsoft intermediate language (MSIL) code that
  implements the types.
• A set of resources.

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Assemblies can be spread across the network
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Assemblies are the security unit

• Each assembly has a set of corresponding grants
• Each grant allows certain permissions
• DnsPermission, Environment, FileDialog, FileIO,
  IsolatedStorage, Reflection, Registry, Security,
  UI, WebPermission, SocketPermission
• The set of grants establishes a security policy
• Grants are determined by CLR managed code
  security policy system.

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Assemblies

• They are also the basic unit for
• Versioning
• Types
• Reference Scope Boundary
• Deployment
• Side-by-side execution
• Can be shared via the Global Assembly Cache (like
  a Squeak Image).

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Application Domains

• Processes provide nice separation of applications
  with separate address, security and run control.
  But causes problems with IPC.
• Application Domains allow multiple applications
  to run in same box, share memory and security
  rights, but also have isolation and individual
  security and run control if desired. So a
  process can run multiple applications!

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Class Library

• Data classes support persistent data management
  and include SQL classes.
• XML classes enable XML data manipulation and XML
  searching and translations.
• Windows Forms support development of Windows GUI
  applications across CLR
• Web Forms include classes that enable you to
  rapidly develop web GUI applications.

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Forms
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C System.Object

• Public methods
• Equals
• GetHashCode
• GetType
• ToString
• Overriding inherited behaviors is common

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C Code and Manifest
using System class MainApp public static
void Main() Console.WriteLine
("Hello World using C!")
.assembly extern mscorlib .publickeytoken
(B7 7A 5C 56 19 34 E0 89 ) // .z\V.4..
.ver 1024110 .assembly Hello // ---
The following custom attribute is added
automatically do not uncomment. ------- //
.custom instance void mscorlibSystem.Diagnostics
.DebuggableAttribute.ctor(bool, // bool)
( 01 00 00 01 00 00 ) .hash algorithm
0x00008004 .ver 0000 .module Hello.exe
// MVID 58AD9DFD-63A6-462A-8AD5-42CBC95AA147
.subsystem 0x00000003 .file alignment 512
.corflags 0x00000001 // Image base
0x03330000
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Web, Windows, Whatever

• Part of the idea is to smooth transitions between
  Windows and Web
• Web interfaces become easier for Windows
  developers
• Windows apps become .NET Web-based apps

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Data lt-gt XML, Everywhere

• All CLR data can be serialized to XML
• All XML can be expanded into CLR data
• Thus, anything can be shipped around on the Web
• Typing through XML Schema
• Pluggable Architecture

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XML Schema

• ltxsdcomplexType name"Person"gt
• ltxsdsequencegt
• ltxsdchoicegt
• ltxsdelement name"name"
  type"xsdstring"
• xsinillable"true" /gt
• ltxsdelement name"id"
  type"xsdstring" /gt
• lt/xsdchoicegt
• ltxsdany processContents"lax"/gt
• lt/xsdsequencegt
• lt/xsdcomplexTypegt
• ltxsdcomplexType name"AgedPerson"gt
• ltxsdcomplexContent mixed"false"gt
• ltxsdextension base"targetPerson"gt
• ltxsdchoicegt
• ltxsdelement name"age"
  type"xsddouble" /gt
• ltxsdelement name"timeOnEarth"
  type"xsddouble" /gt
• lt/xsdchoicegt
• lt/xsdextensiongt
• lt/xsdcomplexContentgt

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Example Instance

• ltnsdon
• xmlnsns"uuid048b2fa1-d557-473f-ba4c-
• acee78fe3f7d"
• gt
• ltnamegtDon Boxlt/namegt
• ltniceStuffForDon/gt
• lt/nsdongt

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Second Example Instance

• ltnsdon
• xmlnsns"uuid048b2fa1-d557-473f-ba4c-acee78f
  e3f7d"
• xmlnsxsi"http//www.w3.org/2001/XMLSchema-in
  stance"
• xsitype"nsAgedPerson"
• gt
• ltnamegtDon Boxlt/namegt
• ltniceStuffForDon/gt
• ltagegt26lt/agegt
• lt/nsdongt

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A Simpler Schema

• ltelement name"Book"gt
• ltcomplexTypegt
• ltelement name"author" type"xsdstring"/gt
• ltelement name"preface" type"xsdstring"/gt
• ltelement name"intro" type"xsdstring"/gt
• lt/complexTypegt
• lt/eBookgt

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Another Example Instance

• lteBookgt
• ltauthorgtHenry Fordlt/authorgt
• ltprefacegtPrefatory textlt/prefacegt
• ltintrogtThis is a book.lt/introgt
• lt/eBookgt

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XML Schema Defined Types
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Class Library Type Hierarchy
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Reading in XML Data

• XmlReader reader
• new XmlTextReader("http//foo.com/don.
  xsd")
• XmlSchema schema XmlSchema.Load(reader, null)
• schema.Compile(null) // turn xml into objects
• reader.Close()

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Serialized Classes
public class OrderForm public DateTime
OrderDate private int foo
ltOrderFormgt ltOrderDategt12/12/01lt/OrderDategt
lt/OrderFormgt
Note Only public instance data and properties
are serialized with XML.
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ALL Interprocess Communication via SOAP

• ALL Interprocess communication (across network or
  on same machine) is through SOAP
• Simple Object Access Protocol
• Its a way of exchanging data and even calling
  other methods/threads, all via XML and plain old
  HTTP requests

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SOAP 1.2

• SOAP is a lightweight protocol intended for
  exchanging structured information in a
  decentralized, distributed environment. SOAP uses
  XML technologies to define an extensible
  messaging framework, which provides a message
  construct that can be exchanged over a variety of
  underlying protocols. The framework has been
  designed to be independent of any particular
  programming model and other implementation
  specific semantics.

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Example SOAP Request

• ltsoapEnvelope xmlnssoap"http//schemas.xmlsoap.
  org/soap/envelope/"gt
• ltsoapBodygt
• ltxTransferFunds xmlnsx"urnexamples-orgban
  king"gt
• ltfromgt22-342439lt/fromgt
• lttogt98-283843lt/togt
• ltamountgt100.00lt/amountgt
• lt/xTransferFundsgt
• lt/soapBodygt
• lt/soapEnvelopegt

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Example SOAP Response
ltsoapEnvelope xmlnssoap"http//schemas.xmlsoap.
org/soap/envelope/"gt ltsoapBodygt
ltxTransferFundsResponse xmlnsx"urnexamples-org
banking"gt ltbalancesgt
ltaccountgt ltidgt22-342439lt/idgt
ltbalancegt33.45lt/balancegt
lt/accountgt ltaccountgt
ltidgt98-283843lt/idgt
ltbalancegt932.73lt/balancegt
lt/accountgt lt/balancesgt
lt/xTransferFundsResponsegt lt/soapBodygt
lt/soapEnvelopegt
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Example SOAP Fault
ltsoapEnvelope xmlnssoap"http//schemas.xmlsoap.
org/soap/envelope/"gt ltsoapBodygt
ltsoapFaultgt ltfaultcodegtsoapServerlt/fau
ltcodegt ltfaultstringgtInsufficient
fundslt/faultstringgt ltdetailgt
ltxTransferError xmlnsx"urnexamples-orgbank
ing"gt ltsourceAccountgt22-34243
9lt/sourceAccountgt
lttransferAmountgt100.00lt/transferAmountgt
ltcurrentBalancegt89.23lt/currentBalancegt
lt/xTransferErrorgt
lt/detailgt lt/xTransferFundsgt
lt/soapBodygt lt/soapEnvelopegt
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Soap Request with Security
ltsoapEnvelope xmlnssoap"http//schemas.xmlsoap.
org/soap/envelope/"gt ltsoapBodygt
ltxTransferFunds xmlnsx"urnexamples-orgbanking
"gt ltfromgt22-342439lt/fromgt
lttogt98-283843lt/togt ltamountgt100.00lt/amountgt
lt!-- security credentials --gt
ltcredentialsgt ltusernamegtdavelt/usernamegt
ltpasswordgtevadlt/passwordgt
lt/credentialsgt lt/xTransferFundsgt
lt/soapBodygt lt/soapEnvelopegt
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MS .Net
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ASP.NET

• ASP gt Active Server Pages
• Put most of the computation in the server
• Very simple model to use
• ADO.NET is the database connection part

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Calling Web Services

• Any class can be converted into an XML Web
  Service with just a few lines of code, and can be
  called by any SOAP client. 

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Take-away lessons

• VMs are important
• Even Microsoft thinks so
• Distributed apps are important, but to do so
  requires standard protocols
• Ways of serializing data (XML)
• Ways of doing RPC (SOAP)
• Design Decisions Good and Bad

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Limitations of the .NET Framework

• What if youre not on the network?
• Maybe thats not an issue?
• Mapping between XML and any object is hard
• Any object is controlled by compiler. XML can
  be written by anybody with a text editor.
• Theres a whole bunch of class support for
  modified serializers and compilers

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J2EE versus Microsofts .NET

• J2EE has been around longer
• .NET released in 2002
• but Microsoft Transaction Server (MTS) and
  Component Object Model (COM) are older
• Dec 2001 survey shows 78 using J2EE
• 22 using .NET
• Microsoft claims better performance with Pet
  Store example
• but Sun says it isnt a fair comparison
• Microsoft used stored procedures
• Pet store is an example, not a speed test

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