chapter02 - • Introduction • Architecture Models •...

Info iconThis preview shows pages 1–14. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: • Introduction • Architecture Models • Fundamental Models • Summary Chapter 2: System Model What is a model? • Each model is intended to provide an abstract , simplified but consistent description of a relevant aspect of distributed system design Architecture model • Architecture model – define the way in which the components of systems interact with one another – define the way in which they are mapped onto the underlying network of computers • Including – Client-server model – Peer process model – Variations of the client-server model Fundamental model • Are concerned with a more formal description of the properties that are common in all of the architectural models • Including – The interaction model: deal with performance and with the difficulty of setting time limits in a distributed system – The failure model: give a precise specification of the faults that can be exhibited by processes and communication channels – The security model: discuss the possible threats to processes and communication channels • Introduction • Architecture Models • Fundamental Models • Summary Chapter 3: System Model • Simplifies and abstracts the functions of the individual components – Achieved by classify processes as server, client and peer processes • Then considers: – The placement of the components – The interrelationships between the components Build architectural models Software and hardware service layers in distributed systems Applications, services Computer and network hardware Platform Operating system Middleware Platform • Are the lowest-level hardware and software layers • e.g.- Intel x86/Windows- Intel x86/Linux- Intel x86/Solaris- SPARC/SunOS- PowerPC/MacOS Middleware • Its purpose is to mask heterogeneity and provide a convenient programming model e.g. OMG’s CORBA, Java RMI, DCOM • Support of abstractions- Remote method invocation: Sun RPC- Group communication: Isis- Notification of events- The replication of shared data- Transmission of multimedia data Limitation of middleware • some systems require support at the application level. E.g. transfer of large electronic mail • ‘ the end-to-end argument’ [1984] – some communication-related functions can be completely and reliably implemented only with the knowledge and help of the application standing at the end points of the communication system E.g. TCP, DNS and the Web System architectures • The division of responsibilities between system components (applications, server and other processes) and the placement of the components on computers in the network • Be historically the most important and remain the most widely employed • Servers may in turn be clients of other servers Arch. 1: Client/Server Server Client Client invocation result Server invocation result Process: Key: Computer: • Partition service objects on different servers – e.g. Web, CDAL • Maintain replicated service objects on several hosts – e.g. Sun NIS, realcourse Arch. 2: Services provided by multiple servers Server Server Server Service Client Client •...
View Full Document

Page1 / 55

chapter02 - • Introduction • Architecture Models •...

This preview shows document pages 1 - 14. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online