Distributed Object Based System

8/4/2019 Distributed Object Based System

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Distributed Document-BasedSystems

Chapter 11

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The World Wide Web

Overall organization of the Web.

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Document Model (1)

A simple Web page embedding a script written in JavaScript.

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Document Model (2)

An XML definition for referring to a journal article.

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Document Model (3)

An XML document using the XML definitions from previous slide

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Document Types

Six top-level MIME types and some common subtypes.

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Architectural Overview (1)

The principle of using server-side CGI programs.

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An HTML document containing a JavaScript to be executed by the server

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Architectural details of a client and server in the Web.

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HTTP Connections

a) Using nonpersistent connections.

b) Using persistent connections

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HTTP Methods

Operations supported by HTTP.

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HTTP Messages (1)

HTTP request message

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HTTP Messages (2)

HTTP response message.22

HTTP Messages (3)

Some HTTP

messageheaders.

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Clients (1)

Using a plug-in in a Web browser.

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Clients (2)

Using a Web proxy when the browser does not speak FTP.

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Servers

General organization of the Apache Web server.28

Server Clusters (1)

The principle of using a cluster of workstations to implement a Web service.

- horizontal distribution -

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Server Clusters (2)

(a) The principle of TCP handoff.30

Server Clusters (3)

(b) A scalable content-aware cluster of Web servers.

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Uniform Resource Locators (1)

Often-used structures for URLs.

b) Using only a DNS name.

c) Combining a DNS name with a port number.

d) combining an IP address with a port number.

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Uniform Resource Locators (2)

Examples of URLs.

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Uniform Resource Names

The general structure of a URN

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Web Proxy Caching

The principle of cooperative caching38

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Server Replication

The principle working of the Akami CDN.40

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Security (1)

The position of TLS in the Internet protocol stack.

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Security (2)

TLS with mutual authentication.44

Distributed Coordination-BasedSystems

Chapter 12

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Introduction to Coordination Models

A taxonomy of coordination models (adapted from[cabri.g2000]) 46

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Overview of Jini

The general organization of a JavaSpace in Jini.50

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Architecture

The layered architecture of a Jini System.

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Communication Events

Using events in combination with a JavaSpace54

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Processes (1)

A JavaSpace can be replicated on all machines. The dotted lines show thepartitioning of the JavaSpace into subspaces.

b) Tuples are broadcast on WRITE

c) READs are local, but the removing of an instance when callingTAKE must be broadcast

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Processes (2)

Unreplicated JavaSpace.

b) A WRITE is done locally.

c) A READ or TAKE requires the template tuple to bebroadcast in order to find a tuple instance

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Processes (3)

Partial broadcastingof tuples andtemplate tuples.

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The Jini Lookup Service (1)

The organization of a service item.

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The Jini Lookup Service (2)

Examples of predefined tuples for service items.

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Synchronization of Transactions

The general organization of a transaction in Jini. Thick lines showcommunication as required by Jini's transaction protocol 64

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Security

The position of PAM with respect to security services.

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Documents

Distributed Object Based System