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Course Information & Overview |
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Qusay H. Mahmoud |
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qmahmoud@sce.carleton.ca |
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This is not a theory course |
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It is a SKILLS course |
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Understand the basics of networking |
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Learn about the different technologies that can
be used to develop distributed applications |
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Work effectively in groups to develop a
significant distributed application |
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If it is your first course in networking, you
will develop an idea of where to go next |
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Networking Basics |
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Sockets |
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RMI |
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CORBA |
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Agents and Mobile Code |
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CGI, Servlets, JSP |
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Middleware and XML |
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Jini, JavaSpaces, WebServices |
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Security Issues |
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Broad set of related technical topics |
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We will not be able to cover all topics in
details |
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For some topics, the course is more like an eye
opener |
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Do not expect to become an expert in every
single topic that we will cover |
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It is almost impossible to master all the
technologies we will cover in the course |
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URL: http://www.sce.carleton.ca/~qmahmoud/sce580 |
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Lectures: Tue & Thu 5:30 – 7:00 ME 3174 |
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Book: Distributed Programming with Java |
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http://www.manning.com/Mahmoud |
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Assignments (20%): two assignments |
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Midterm (30%): March 1st |
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Project (50%) |
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Project idea (5%) |
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Design (10%) |
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Implementation, documentation, and functionality
(15%) |
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Presentation (10%) |
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Final paper (10%) |
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Read notes in advance if possible |
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Discuss concepts |
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Ask questions |
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Read |
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Explore |
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Experience writing distributed Java-based
applications |
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Appreciate the beauty of Java J |
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Homework |
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Programming |
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Project |
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Discuss ideas with group members |
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See course homepage |
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http://www.sce.carleton.ca/~qmahmoud/sce580 |
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The evolution of computing? |
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Stand-alone computers |
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Mainframes |
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PCs |
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Networked Computing |
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C/S computing |
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The Internet (and Web) factor |
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The Java factor |
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Start with a single processor used exclusively
by one user |
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Users have to share the computer by competing
for time slots |
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A single computer used by many users |
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Every user has a terminal |
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Processing is done at the mainframe computer |
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Relatively cheap computers used by one user |
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Stand-alone model describes today’s home users |
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Programs delivered on disks (floppy, CDs, etc) |
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The Internet is now delivering content, both
data and programs |
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More users rely on computers to do their jobs |
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Terminals substituted with PCs &
workstations |
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Data communication is important as programs are
brought to a local processor for execution |
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Users have to share data |
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Monolithic programs are divided into two parts: |
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Client & Server |
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Client applications run on local machines |
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Server applications run on centralized machines |
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Applications that run on corporate computers
require the presence of servers |
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Users share storage and processing resources |
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The network is part of the computing platform |
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Initially closed, homogeneous environments (e.g.
Unix, NFS, Windows, etc) |
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CORBA for heterogeneous environments…. |
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Attempts to connect all private and public
networks |
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DARPA’s IP is the de-facto standard for
exchanging data between different networks |
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TCP is the de-factor standard transport protocol
over IP (combo as TCP/IP) |
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The easiness of exchanging via e-mail, file
transfer, etc. catches the eyes of the big industry players |
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What is the most useful piece of software of the
90’s? The browser! |
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The browser is becoming an operating system for
many users |
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Traditional network applications (e.g. email)
have been incorporated in the browser |
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New business opportunities emerged (e-commerce) |
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New technologies to address arising
challenges(e.g. search engines, agents) |
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Portability |
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Platform independent |
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Java bytecodes can be executed on any computer
with a JVM |
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Web browsers implement the JVM |
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Possible to enhance Web pages (applets) |
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Remote objects can be upgraded online by pushing
new bytecodes to the hosting JVM |
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System management |
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Plug ‘n play components |
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Software distributed and upgrading |
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Network management |
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Fault diagnosis |
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Error recover |
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Network and service discovery |
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Plug ‘n play networks |
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Electronic commerce |
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Buying agents (brokers) |
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Selling agents |
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Investment |
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Secure communication protocols |
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Remote control |
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Remote operation |
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Robots |
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Soft bots |
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Remote expertise |
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Medical |
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Legal & counseling |
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Distance learning |
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Multimedia distribution |
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Personalized news |
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Intelligent targeting of ads |
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Video on demand |
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Cooperative problem solving |
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Distributed planning |
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Resource allocation |
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Scheduling |
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Data mining |
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Filtering based on mobile agents (collectors,
reporters) |
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Filtering info at the source (e.g. stock market) |
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Others…. |
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Explore the user of XML for middleware |
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Anything interesting that involves distribution
(Sockets, RMI, CORBA, Mobility, Jini, EJB, etc) |
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Think of something compelling and innovative |
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Give you an idea and a flavor of the topics |
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Try to pick a technology that interests you the
most OR a topic that is related to your real-world job or thesis or
project….and use this for your class project if you like |
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IP: Internet Protocol |
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TCP: Transmission Control Protocol |
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UDP: User Datagram Protocol |
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TCP vs. UDP |
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TCP is connection-oriented (UDP is not) |
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TCP is reliable (UDP is not) |
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TCP has no size limit on messages (UDP: 64KB) |
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Analogous to telephones – provide the user with
an interface to the network |
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Think of a socket as an end point of a Unix pipe |
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Used in the same way as a file descriptor: |
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Creation (open socket) |
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Read/write (receive/send to socket) |
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Destruct (close socket) |
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Types: SOCK_STREAM, SOCK_DGRAM, SOCK_RAW |
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RMI is a core package of Java 1.1+ |
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The power of Java interfaces (no protocols) |
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Methods can be invoked from JVMs, possibly
running on remote hosts |
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Common Object Request Broker Architecture |
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A specification for creating and using
distributed objects |
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It is not a programming language |
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Interfaces in IDL |
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Language-independent |
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Heterogeneous language environment |
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Garbage collector (No) |
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In, out, inout parameters |
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Pass by reference |
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Interfaces in Java |
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Java-based |
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Homogenous language environment |
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Garbage collector (Yes) |
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No such parameters |
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Pass by copy (local objects), by reference to
stub (remote objects) |
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An agent is an entity that: |
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Acts on behalf of others in autonomous fashion |
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Proactive Reactive |
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Exhibits some levels of the key attributes of
learning, cooperation, mobility (mobile agents) |
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Server-side technology |
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Mainly used to interpret fill-out forms |
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CGI scripts can be written in any language |
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Acts as a gateway between output/input |
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Environment variables: |
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REMOTE_HOST, REMOTE_ADDR |
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CONTENT_TYPE, CONTENT_LENGTH |
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QUERY_STRING |
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Stateless |
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Server-side technology |
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Designed to overcome some limitations of
existing technologies (e.g. CGI is stateless) |
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Characteristics: |
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A light-weight task that can be executed as a
thread |
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servlet can remain in memory (a CGI script terminates when it finished) |
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Advantages: |
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A servlet can service multiple client requests |
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Can handle multiple clients without
reloading/reinitialization |
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Server-side technology |
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Enables you to embed Java code within an HTML
document |
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JSP documents have the extension .jsp |
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When an HTTP request is received, the
compilation engine converts the JSP document into a Java Servlet then the
servlet will be loaded |
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Java code is embeded between <% and %> |
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In essence, it is about meaningful annotation |
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Syntactically, XML docs look like HTML docs |
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XML documents can be: |
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Well-formed (conforms to the XML syntax) |
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Valid (conforms to its DTD) |
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Extends HTML linking capabilities: |
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Xlink: how two documents can be linked |
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Xpointer: enables addressing of individual parts |
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Xpath: used by Xpointer to describe location
paths |
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Pronounced “Gee-nee” |
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A network infrastructure on top of Java to
create a “federation” of virtual machines |
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Discovery/Join/Lookup
Protocols |
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We will have an into to cryptography |
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JDK1.0 security model: |
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Sanbox (SecurityManager) |
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JDK1.1 security model: |
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Sandbox + signed code |
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JDK1.2 (Java 2) security model: |
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Protection domains (security policies) |
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Sandbox (compatible with JDK1.0 JDk1.1) |
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Notes