Education4U

Distributed Systems

Lec-01 : What is Distributed systems ?

Description

• A distributed system consists of multiple nodes that are physically separate but connected using the network.

• All the nodes in this system communicate with one another and handle processes in tandem. Each of these nodes includes a small part of the distributed operating system software.

Prerequisite

Before start learning DS its better to have a knowledge on Data communication and operating system basic concepts. So that it may help you to understand DS more easily.

Topics Covered

• Models • Remote Procedure call • RMI • Process concepts • CORBA

• Physical & Logical clocks • Security & Mutual exclusion

• Distributed Database • Parallel Database

For whom

• For computer science students to help them understand the basic to advanced concepts related to the distributed system.

• Students those who are preparing them for their Engineering Syllabus.

Reference books

1.“Advanced Concepts in Operating Systems” by Mukesh Singhal and Niranjan Shivaratri

2.“Distributed Algorithms” by Nancy Lynch

3. “Distributed Operating Systems” by Andrew S Tanenbaum

4.“Distributed Systems” by Jie Wu

Q & A
Exam Questions

Q1 . What kind of reliable connection is provided by a TCP/IP based socket? Is this reliability enough for distributed calls or when does it break down?
Q2 . What are stub and skeleton and why are they needed in remote procedure calls?
Q3 . What services are frequently provided by distributed systems middleware and what is their function?
Q4 . Why do you need a locking service in distributed systems? What kind of problems does a locking service prevent?
Q5 . Explain distributed 2-phase commit protocol.
Q6 . What is the big advantage of public-key mechanisms in distributed systems?
Q7 . What is end-to-end security in distributed systems?
Q8 . Name two mechanisms that can be used to ensure performance in distributed systems
Q9 . List some architectures that you need to define for distributed systems
Q10 . What are the differences between a URL, URI, and URN?

Mobile Computing devices are being carried around have advantages when using different devices (Laptops & Printers)
Ubiquitous - Little computing devices are all over the place. It is used in a single environment (Home or Hospital)

The extent to which a computer system can be expanded and implemented.
Ex: IEEE 802.11 WLAN, IEEE 802.3 Ethernet, W3C = World Wide Web Consortium , HTML Recommendations

• Encryption: Ex: Blowfish, RSA
• Authentication: Ex: Password, Public key authentication
• Authorization: Ex: Access control lists

Confidentiality: Against disclosure to an unauthorized individual.
Integrity: Against alteration or corruption.
Availability: Against interference targeting access to the resources.
Non-repudiation: Proof of sending/receiving information

The system should work effectively on many different scales from small internet to the Internet.
Challenges of designing scalable distributed systems:
• Cost of physical resources
• Cost should linearly increase with system size
• Performance Loss

• Architecture model
• Fundamental model
• Interaction model
• Failure model
• Security model

• The middleware is a layer of software whose purpose is to conceal heterogeneity and provide a convenient programming model for application programmers.
Middleware is represented by a group of processes or objects in a computer to realize communication and resource sharing support for distributed applications.

The term protocol is used to refer to a well-known set of rules and formats that will be used for communication between processes to perform a given task.
The definition of a protocol has two important parts to it:
• A specification of the sequence of messages that must be exchanged;
• A specification of the format of the data in the messages.

The IP protocol transmits datagrams from one host to another through an intermediate router when necessary. Transmission and routing algorithms use multiple header fields.

• Mobile IP is an Internet Engineering Task Force (IETF) standard communication protocol designed to allow mobile device users to move from one network to another while retaining their permanent IP address.
• Mobile IP is defined in the Request for Comments (RFC), which is an enhancement to the Internet Protocol (IP), which is used to forward Internet traffic to the mobile device (called a mobile node) when the mobile device is connected through a non-local network. Mechanisms.

The architectural model defines the way system components interact with each other and how they map to the basic computer network.

1. The basic model helps reveal key issues for designers of distributed systems.
2.Their purpose is to specify the design problems, difficulties, and threats that must be resolved to develop a distributed system that can complete its tasks correctly, reliably, and safely.
3.The basic model only provides an abstract view of the characteristics of the distributed system that affect the reliability characteristics (correctness, reliability, and safety).

1. Inter-process communication itself involves not only the communication between processes in a distributed system but also the support for communication between distributed objects.
2.The Java API for inter-process communication on the Internet provides datagram and stream communication.

Independent data entity that carries enough information to be routed from the source to the target computer without relying on the early exchange and transmission network between the source computer and the target computer.

The client-server computing model is a distributed application structure used to divide tasks or workloads between resource or service providers (called servers) and service requesters (called clients).

Group communication is a more suitable multicast operation-this is an operation that sends a message from a process to each member of a group of processes, usually in this way, that is, group membership is transparent to the sender.

1.Preemptive scheduling: A thread may be suspended at any time to make room for another thread, even if the preempted thread will continue to run.
2. Non-preemptive scheduling: a thread runs until the calling thread system, at this time the system may schedule it, and then schedule another thread to run

There are four types of event that the kernel notified to the user level scheduler are:
• Virtual processor allocated.
• Scheduler Activation blocked
• Scheduler Activation unblocked
• Scheduler Activation preempted

Cryptography is a technique that encodes information only in a format that is accessible to the intended recipient.
Uses:
• Secrecy and integrity • Authentication • Digital signatures.

A storage directory service that stores a collection of bindings between names and attributes and finds entries that match an attribute-based specification.
Example: Microsoft’s Active Directory services, X.500, and its cousin LDAP, Universe.

1.It is the realization of group communication.
2.Multicast communication requires coordination and agreement.
3.The purpose is for members of the group to receive copies of messages sent to the group. Many different delivery guarantees are possible

• This algorithm allows the process to crash during elections. Although it assumes that message delivery between processes is reliable.
• It assumes that the system is synchronous-it uses timeouts to detect process failures.

Distributed debugging is just to check whether there is a transitional state rather than a stable state in actual execution.

Shivam

please update the notes , it is outdated.

sanju

Good Course for Beginners

sanju

Good Course

Review :

5 | 1 Reviews

Course Feature

Category Computer Science
Language English
Price 79.00
Validity 1 Year
Rating 5 | 1 Reviews
Q & A 23
Exam Questions 10
Full Course PDF View

Wishlist

Add to Cart

Computer Science

Distributed Systems

Lec-01 : What is Distributed systems ?

Shivam

sanju

sanju

Course Feature

Share

Data Communication

Adhoc & Sensor

Operating Systems(OS)

Software Engineering(SE)

Useful Links

Download

Computer Science

1.Overview

2.Models

3.Operating Systems

4.Remote procedure call

5.RMI

6.Process Concepts

7.CORBA

8.Physical & Logical Clocks

9.Security & Mutual exclusion

10.Distributed Database

11.Parallel Databases

Distributed Systems

Lec-01 : What is Distributed systems ?

1.Overview

2.Models

3.Operating Systems

4.Remote procedure call

5.RMI

6.Process Concepts

7.CORBA

8.Physical & Logical Clocks

9.Security & Mutual exclusion

10.Distributed Database

11.Parallel Databases

Q1 . What is mobile and ubiquitous computing ? Write the difference

Q2 . Why we need openness in a distributed system?

Q3 . What are the security mechanisms used in distributed computing?

Q4 . How we provide security?

Q5 . Define Scalability?

Q6 . What are the different types of system models?

Q7 . What is the use of middleware?

Q8 . Define Protocol?

Q9 . What is meant by internet protocol?

Q10 . Define mobile IP?

Q11 . What is the architectural model?

Q12 . What is the fundamental model?

Q13 . What is meant by inter-process communication?

Q14 . Define Datagram?

Q15 . What is meant by client-server communication?

Q16 . What is meant by group communication?

Q17 . List the two types of thread scheduling? Explain?

Q18 . List the types of events that the kernel notified to the user-level scheduler?

Q19 . What is cryptography? What is the use of it?

Q20 . Explain directory services?

Q21 . Define multicast communication?

Q22 . Write a note on the Bully algorithm?

Q23 . What is distributed debugging?

Shivam

sanju

sanju

Course Feature

Share

Related Courses

Data Communication

Adhoc & Sensor

Operating Systems(OS)

Software Engineering(SE)

Useful Links

Download