middleware-based os distributed os networked os 1meit application distributed operating system...
Post on 27-Dec-2015
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Middleware-Based OS
Distributed OS
Networked OS
1MEIT
Application ApplicationApplication
Distributed Operating System Services
Application ApplicationApplication
Network OS Network OS Network OS
Middleware-based OS
MEIT 2
Application ApplicationApplication
Middleware Operating System Services
Networked OS Networked OSNetworked OS
Generic Middleware
• Communication stacks for c/s communication• Distributed directories for location• Authentication services for security• RPCs for accessing remote functionalities• Queuing services for synchronous & loosely
coupled communications.
MEIT 3
Key services
• Remote Procedure Call• Directory service• Security service• Time service• Threading service• Distributed File service• IDL Compiler• Diskless service
MEIT 5
Directory service
• Cell Directory Service (CDS)
• Global Directory Service (GDS)
• Global Directory Agent (GDA)
• Directory Service Programming Interface
MEIT 6
Directory Service Programming Interface
MEIT 8
Client Machine
Client application
CDS clerk Cache
Server Machine
RPC Server
Server Machine
Clearing house
CDS Server
Service-Specific Middleware
• Needs to accomplish a particular c/s type of service
• OLTP middleware
• Communication middleware
• Object-specific middleware
• Workflow management middleware
• Internet-specific middleware
MEIT 9
Database Middleware
• Database Middleware provides a common interface between a query and multiple, distributed databases.
• Using either a hub and spoke architecture or a distributed architecture it enables data to be consolidated from a variety of disparate data sources
10MEIT
Messaging Middleware
Common interface and transport between applications. – Stores the data in a message queue if
the target machine is down or overloaded
– May contain business logic that routes messages to the appropriate destinations and reformats the data as well.
– Similar to an e-mail messaging system, except that it is used to send data between applications.
11MEIT
Application Server Middleware
• A Web-based application server that provides interfaces to a wide variety of applications is used as middleware between the browser and legacy systems.
– The browser can be used at desktops or on laptops when travelling.
– A wide range of server-side processing has been supported by appservers (i.e.;J2EE).
12MEIT
Types of Middleware Services
1. Distributed system services, • Critical communications, program-to-program, and data management
services. • This type of service includes RPCs, MOMs and ORBs.
2. Application enabling services, • Access to distributed services and the underlying network. • This type of services includes transaction processing monitors and database
services such as Structured Query Language (SQL).
3. Middleware management services, • Which enable applications and system functions to be continuously
monitored to ensure optimum performance of the distributed environment.
13MEIT
Distributed Objects and Distributed Processing
• Distributed objects have the biggest potential to solve a wide range of challenges faced by designers of large software systems.
• Some of these challenges include – component packaging, – cross-language interoperability, – interprocess communication, and– intermachine communication.
• We separate distributed object architectures into two categories:– component architectures and – remoting architectures.
• Component architectures focus primarily on component packaging and cross-language interoperability.
• Remoting architectures focus primarily on support for remote method invocation on distributed objects.
14MEIT
Remoting Architectures
• Open Software Foundation’s (OSF) Distributed Computing Environment (DCE) – which actually is a distributed processing environment based on the Remote
Procedure Call (RPC) paradigm (purely procedural)
• Object Management Group’s (OMG) Common Object Request Broker Architecture (CORBA). – The notion of component packaging and deployment has only recently been
added to CORBA 3.0.
15MEIT
Component Architectures
• Microsoft’s Component Object Model (COM) – addresses packaging and deployment of binary component as well as cross-language
interoperability• JavaBeans and Enterprise Java Beans (EJB) component models
introduced by SUN Microsystems. • Both, COM and EJB address remoting to some extend:
– the COM model has been extended to Distributed COM (DCOM) using an extended version of DCE RPC as transport.
– EJB supports client/server communication based on Java Remote Method Invocation (RMI).
– RMI is special as it integrates closely with the Java language without requiring a special Interface Definition Language (IDL) to describe component interfaces accessible for remote invocations.
• In an evolutionary sense, Microsoft’s .NET is the newest and most advanced component architecture available in the market today.
16MEIT
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