Stages of Complexity

1
Stages of Complexity
Enterprise Computing - DCE - CORBA - Javas
J2EE- .NET framework and servers - SOAPs
buddies gt XML gt WSDL gt UDDI gt more
to come!
Distributed Programming - RPC (C/C) - RMI
(Java) - Remoting (.NET)- DCOM (win32) - invoke
via email (messaging i/f) - winner? SOAP
Network Programming - sockets
Basic Networking - ISO/OSI - addressing -
protocols
2
Enterprise Computing

• Everybody their brother has a framework
• A framework is typically two things
• collection of programs distributed services
• programmers interfaces (APIs)
• Programmers typically use existing services while
  creating their own
• e.g. write RPC client, server and use rpcbind

3
Enterprise Computing Issues

• Scalability
• Reliability
• Security
• Heterogeneity

4
Levels of Computing Design
Enterprise Computing - many middleware
services - non-trivial issues with
concurrency- non-trivial issues with
distribution - rely heavily on code re-use and
design patterns
Complex Computing - many system services -
some concurrent algorithms - some middleware
services - familiarity with design patterns
Essential Computing - good designs -
non-trivial algorithms - some system services
Simple Computing - basic syntax - basic design
5
Some Core Middleware Services

• Handling remote processes data
• Handling remote file I/O
• Naming/Brokering/Trading
• multiple levels
• multiple attributes (yellow pages)
• Security
• authentication, authorization, privacy
• Threading, Synchronization, Transacting

6
Some Frameworks (80s,90s,zips)

• Old-line Unix/Internet Sun RPC friends
• OSF DCE newer RPC-base Unix/Microsoft
• Old-line Microsoft DCOM friends
• CORBA the OO alternative to RPC-base
• Java J2EE Java borrows from CORBA
• .NET newer Microsoft base (and Mono!)
• Web services SOAP friends
• The freeware option and Linux

7
1980s Unix Framework

• Processes local (various IPC), remote (Sun RPC)
• Data Translation XDR
• File I/O local and Network File System (NFS)
• Naming rpcbind,Network Info Service (NIS) was
  Yellow Pages,Domain Name Service (DNS)
• Time sync Network Time Protocol (NTP)
• Threading/Sync pthreads, fork/exec
• Security basic authentication and authorization
• And GUI too Tcl/Tk, X Windows, OSF Motif

8
OSF DCE

• Open Software Foundation created Distribute
  Computing Environment early 1990s
• Processes DCE RPC, Interface Definition Language
  (IDL)
• File I/O Distributed File System (DFS)
• Naming rpcd, Cell Directory Service (CDS)
• Time sync DECs Distribd Time Service (DTS)
• Security Kerberos (from MIT, 1980s)
• Interoperates with old-line Unix framework

9
DCEs Contributions

• Pulled Unix community (and Microsoft) around
  distributed processing standard
• First attempt to pull together middleware pieces
• Systematically addressed scalability in each part
• OSF also tried network management
• Distributed Management Environment (DME)
• brought together network management standards
• fizzled after OSF ran into financial woes

10
Microsoft Frameworks of Old

• The Programmers choices/tools
• the win32 API (basic OS resources)
• Microsoft Foundation Classes (MFC)
• Web programming tools
• ActiveX Template Library (ATL)
• Active Server Pages (ASP)
• Internet Server API (ISAPI)
• Email Collaboration Data Objects (CDO)

11
More Historical Microsoft

• Database (ActiveX Data Objects - ADO)
• ODBC, DAO, RDO, whatever
• Distributed COM, DCOM, COM
• sockets and DCE RPC also available
• Enterprise servers
• SQL Server
• Exchange Server
• many, many more!

12
CORBA

• Essential idea object request broker (ORB)
• CORBA Common ORB Architecture
• CORBA RMI IDL (interface defn. lang.)
• CORBA services and features
• naming, trading
• handling and routing of events, notifications
• security
• interoperability via Inter-ORB protocol

13
CORBAs Contributions

• Provided a rallying point for OO RPC
• industry was stuck on traditional RPC
• Pioneer in inter-organization (enterprise)
  computing
• predecessor Electronic Data Interchange (EDI)
• Object Mgmt Group created CORBA in 1991
• version 2.0 specification arrived in 1996
• glue Internet Inter-ORB Protocol (IIOP)
• challenger for future dominance SOAP

14
J2EE Components

• RMI and registry
• Database (JDBC) and File I/O
• Threads and synchronization
• Graphics (2D/3D), windows, GUI (Swing)
• Java Servlets API, JavaServer Pages (JSP)
• JAX packages (XML services)
• Enterprise JavaBeans components
• Security
• Email, Web services

15
.NET Framework Classes

• Remoting (RMI), Message (email)
• Database and File I/O (local distributed)
• Security
• Data presentation with XML
• Web Services and web communication
• Graphics (2D/3D), windows, GUIs
• Threads and synchronization
• 3500 classes (so far)

16
The Magic Word Transparency

• Access transparency
• Location transparency
• Concurrency transparency
• Replication transparency
• Failure transparency
• Migration transparency
• Performance transparency
• Scaling transparency

17
Problem of Distributed State

• A huge problem of distribution
• Hard to keep everybody on the same page
• Some sub-problems
• controlling massive amounts of concurrency
• handling uncertain message delays
• dealing with failures (versus monolithic failure)
• changing state in gt1 place (two-phase commits)
• increased security risk

18
The Network Operating System

• Same basic five tasks of an OS
• Process management (including sync)
• Memory management
• File/Storage management
• Security
• Device management
• Device mgmt naming/brokering
• everything on the net is a resource/device

19
Web Services

• SOAP Simple Object Access Protocol
• THE wave of the decade
• On track to become the standard for remote
  procedure/method call/invocation
• Works across all platforms and all languages
• Built on top of HTTP and XML
• WSDL Web Service Description Language
• The interface definition mechanism for SOAP
• UDDI Universal Description, Discovery and
  Integration
• Essential protocol for clients/servers to connect

20
Futures

• Agents AI embedded in distributed systems
• P2P peer-to-peer rather than client/server model
• Grid Computing massively distributed tasks
• Pervasive Computing
• small wireless computers everywhere
• often embedded in more natural objects