Software engineering and Middleware : a Roadmap Wolfgang Emmerich

1
Software engineering and Middleware a
Roadmap Wolfgang Emmerich

• Presented by
• Tarun Nainani
• CS589_Fall2007

2
Overview

• Middleware overview
• Distributed Systems overview
• Paper Overview
• Paper Summery
• Middleware in Embedded Software
• Weakness Strengths

3
Middleware ?

• In a distributed computing system, middleware is
  defined as the software layer that lies between
  the operating system and the applications on each
  side of the system.
• Middleware is computer software that connects
  software components or applications.
• Middleware is connectivity software that consists
  of a set of enabling services that allow multiple
  processes running on one or more machines to
  interact across a network.

4
Middleware
5
Functions of Middleware

• Hiding distribution, i.e. the fact that an
  application is usually made up of many
  interconnected parts running in distributed
  locations.
• Hiding the heterogeneity of the various hardware
  components, operating systems and communication
  protocols
• Providing uniform, standard, high-level
  interfaces to the application developers and
  integrators, so that applications can be easily
  composed, reused, ported, and made to
  interoperate
• Supplying a set of common services to perform
  various general purpose functions, in order to
  avoid duplicating efforts and to facilitate
  collaboration between applications.

6
Middleware in action

• Thousands of physicists at hundreds of
  laboratories and universities worldwide come
  together to design, create, operate, and analyze
  the products of a major detector at CERN, the
  European high energy physics laboratory. During
  the analysis phase, they pool their computing,
  storage, and networking resources to create a
  "Data Grid" capable of analyzing petabytes of
  data.

7
Middleware in Action

• Middleware services deployed across industry and
  higher education institutions work seamlessly
  together to verify students electronic
  identities, permit remote access to libraries,
  and deliver streamed-video classroom content. The
  students are not continually asked for usernames,
  passwords or account numbers, because the
  institutions and their constituents trust open
  standards for authentication, information sharing
  and privacy management.

8
Middleware in Action

• A crisis management team responds to a chemical
  spill by using local weather and soil models to
  estimate the spread of the spill, determining the
  impact based on population location as well as
  geographic features such as rivers and water
  supplies, creating a shortterm mitigation plan
  (perhaps based on chemical reaction models), and
  tasking emergency response personnel by planning
  and coordinating evacuation, notifying hospitals,
  and so forth.

9
Middleware in Action

• Administrators and faculty at a U.S. university
  access a broad range of services through a secure
  portal that uses middleware in the background to
  permit powerful calendar applications, desktop
  video and IP telephony. Whether in an office or
  an airport, the user comes to depend on
  middleware services for quality-of-service,
  security and privacy to access and share data
  with colleagues on campus and across the country.

10
The Middleware Diagram
11
Distributed Computing

• Distributed computing is a method of computer
  processing in which different parts of a program
  run simultaneously on two or more computers that
  are communicating with each other over a network

12
Goals of Distributed computing

• The main goal of a distributed computing system
  is to connect users and resources in a
  transparent, open, and scalable way.
• Openness
• Monotonic
• Pluralism
• Unbounded non-determinism

13
Paper Overview

• Introduction
• Distributed Systems
• Role of Middleware
• Middleware overview
• Middleware Solutions
• Middleware State-Of-The-Art
• Middleware and Software Engineering
• Summery

14
Introduction

• Increasing demand for distributed systems
• Mergers between companies is continuing to
  increase
• Need of Integration
• Time available for integration is deceasing
• Scalability is important issue

15
Distributed systems a Solution

• Distributed systems can solve the above problems
  as they-
• Integrate Legacy components
• Decrease time to market
• Fault-tolerant
• Scalable
• Complex
• Multiple points of failure
• A better fit for integrated, highly scalable,
  and adaptable systems

16
Problems With Distributed Systems

• Not easy to build
• If not planned properly, a distributed system can
  decrease the overall reliability of computations
  if the unavailability of a node can cause
  disruption of the other nodes.
• Security issues

17
Role of Middleware

• It simplifies distributed system construction
• They resolve heterogeneity
• Facilitates communication and coordination of
  distributed components.

18
Which Middleware to choose and how??

• In order to build distributed systems that meet
  the requirements,software engineers have to know
  what middleware is available.
• Which one is best suited to the problems at hand?
• and how middleware can be used in the
  architecture, design and implementation of
  distributed systems.

19
Typical Middleware Requirements

• Network Communication
• Coordination
• Reliability
• Scalability
• Heterogeneity
• Enhanced Security
• Application Oriented services
• Interaction with other network services.
• http//video.google.com/videoplay?docid-818615
  82465072488qmiddlewaretotal113start0num10
  so0typesearchplindex2

20
Network Communication

• Implement lower level network layers
• - DS are usually built on top of transport
  layer.
• Provide higher level primitives
• - app engineers should be able to request
  parameterized services
• Support marshalling unmarshalling

21
Co-ordination

• Support concurrent execution by synchronization
  based on threading policies
• - deferred synchronous client
• - asynchronous - server
• Restore component states based on activation
  policies.

22
Reliability

• Handle individual requests
• - Best Effort
• - Atmost once
• - Atleast once
• - Exactly Once
• Handle multiple requests
• - K reliability
• - Time outs
• - Totally Ordered
• Accommodate different levels and extensions
  (reliable delivery, order preservation, ACID
  properties)
• Support replication

23
Scalability

• Load Balancing
• -Access transparency
• -Location transparency
• -Migration transparency
• -Replication transparency

24
Heterogeneity

• Integrate elements from various contexts
• -hardware
• -software
• -operating system
• -middleware
• Support interoperability

25
Middleware Solutions

• Transactional Middleware
• -Transactional middleware supports transactions
  involving components that run on distributed
  hosts.
• Message-oriented Middleware
• -supports the communication between distributed
  system components by facilitating message
  exchange.

26
Middleware Solutions

• Procedural Middleware
• -These are based on RPC Remote Procedure Calls
  (RPCs) were devised by Sun Microsystems in the
  early 1980s as part of the Open Network Computing
  (ONC) platform.
• Object and Component Middleware
• -idea here is to make object-oriented
  principles, such as object identification through
  references and inheritance, available for the
  development of distributed systems

27
Middleware Solutions
28
Middleware Solutions .
29
Weakness

• Transactional
• - it creates undue overhead if there is no
  use of transactions.
• - marshalling and unmarshalling needs to be
  done manually.
• - portability is reduced due to no
  standardized approach for defining the services
  offered by server components
• MOM
• - Supports only at-least once reliability
• - Does not support ACID properties
• - Limited support for scalability and
  heterogeneity.
• RPC
• - Not scalable and fault tolerant
• - Not reflexive

30
State-of-art

• Flexible Middleware
• 1)Trading using a trader in place of naming
  service/mechanism
• 2)Reflection mechanism to discover the types
  of the classes and define method invocation at
  runtime
• 3)Application-level Transport Protocol
• Scalable Middleware
• -Replication
• Real-time Middleware
• - Lack on prioritization on requests
• - High memory requirements
• Middleware for Mobile Computing
• - Lack of continuous bandwidth availability
• - Problems of network outages
• - Increased complexity of software and size
  efficient data representation

31
Middleware and Software Engineering Research

• Requirements Engineering
• 1)quantification of non-functional goals
• 2)adaptation to unstable requirements
• Software Architecture
• 1)addressing global properties and non
  functional requirements
• 2)alibrated models for validation
• 3)Distributed software engineering research
  needs to identify notations,
  
  
  methods and tools that support architecting.
• Design
• 1)development of middleware design notations,
  methods, and tools

32
Middleware in Embedded Software

• Embedded software
• -specialized
• -demanding QoS on certain sub domains
  (telecommunications, multimedia, command control
  systems)
• Middleware
• -simplify composition and configuration of
  distributed systems
• -limitations exist (lack of real-time features
  prioritization, performance optimizations,
  non-functional requirement support, heavy memory
  requirements)
• -future is promising (industry supported
  flexible, adaptable, optimized, and standardized
  infrastructures, e.g Real-time CORBA, TAO)

33
Comments

• Likes
• - One of the better roadmap papers.
• - Systematic
• - timeline
• - Good identification of relation between SE
  and MW.
• - Future needs well identified.
• Dislikes
• - No explanation of relation between SE and MW
• - Security aspect has been ignored.

34
Discussion

• !!Thank You!!