Applications and Services in the Internet · Session Initiation Protocol (SIP) Representational...

Applicationsand Services

in the Internet

JaakkoKangasharju

Introduction

Architecturesfor InternetApplications

Client-ServerArchitecturesSession InitiationProtocol (SIP)

RepresentationalState Transfer(REST)

Peer-to-PeerArchitecturesUnstructured P2PNetworks

Structured P2PNetworks

Applications and Services in the InternetSpecial Course in Data Communications Software (7 cr)

Jaakko [email protected]

Helsinki University of Technology

Autumn 2008

Jaakko Kangasharju (TKK) Applications and Services in the Internet Autumn 2008 1 / 34


in the Internet

JaakkoKangasharju

Introduction






Outline

1 Introduction

2 Architectures for Internet Applications

3 Client-Server Architectures

4 Peer-to-Peer Architectures



in the Internet

JaakkoKangasharju

Introduction






Outline

1 Introduction






in the Internet

JaakkoKangasharju

Introduction






Applications in the Internet

• Layered network architecture: Application layer abovetransport layer

• The end-to-end principle: Application functionality cannotimplemented as part of the communication subsystem



in the Internet

JaakkoKangasharju

Introduction









Net Net Net Net

Trans

App

Trans

App



in the Internet

JaakkoKangasharju

Introduction









Net Net Net Net

Trans

App

Trans

App

Net Net

Trans

App



in the Internet

JaakkoKangasharju

Introduction






Services in the Internet

• Services manage resources and provide access to them• Service-Oriented Architecture

• Loose coupling• Service composition



in the Internet

JaakkoKangasharju

Introduction






General Requirements

• Availability• Efficiency• Flexibility• Reliability• Scalability• Security• Simplicity



in the Internet

JaakkoKangasharju

Introduction






Outline

1 Introduction






in the Internet

JaakkoKangasharju

Introduction






Basic Service Architectures

• Certain architectures repeat themselves in multiple services• Different architectures needed for different priorities



in the Internet

JaakkoKangasharju

Introduction






Client-Server Architecture

C C C C

S

• Server host provides a service, client hosts connect to itdirectly



in the Internet

JaakkoKangasharju

Introduction






Client-Server Properties

• Simple and efficient• Security simple to do• Server a single point of failure⇒ Availability, reliability, scalability?



in the Internet

JaakkoKangasharju

Introduction






Enhancing Client-Server

• How to fix client-server’s problems?

• Replicate server, multiple identical servers remove singlepoint of failure

• Federate server, different areas of responsibility providescalability



in the Internet

JaakkoKangasharju

Introduction






Enhancing Client-Server

• How to fix client-server’s problems?• Replicate server, multiple identical servers remove singlepoint of failure

• Federate server, different areas of responsibility providescalability



in the Internet

JaakkoKangasharju

Introduction






Client-Mediator-Server Architecture

C C C C

MM M M

S S

• Mediator component added between client and server



in the Internet

JaakkoKangasharju

Introduction






Client-Mediator-Server vs. Client-Server

• Client-mediator-server more flexible• E.g., caching provides improved efficiency, scalability,availability

• End-to-end security harder• Increases complexity



in the Internet

JaakkoKangasharju

Introduction






Peer-to-Peer Architecture

P P

P P

P P

• All hosts equal, any host can provide service



in the Internet

JaakkoKangasharju

Introduction






Peer-to-Peer Properties

• Available, flexible, efficient• Depending on technology, can be scalable• How to find provided service?• Security and trust issues



in the Internet

JaakkoKangasharju

Introduction






Designing an Architecture

• Requirements phase• Using requirements to pick styles• Identifying components and their communication• Optimizing architecture



in the Internet

JaakkoKangasharju

Introduction






Deriving the Architectural Style

• Derive architectural style based on requirements• Two processes

• Assemble familiar building blocks until requirementssatisfied

• Identify constraints in requirements to limit design space• Different requirements lead to different fundamental styles• Fundamental styles combined to form overall style



in the Internet

JaakkoKangasharju

Introduction






Outline

1 Introduction


3 Client-Server ArchitecturesSession Initiation Protocol (SIP)Representational State Transfer (REST)




in the Internet

JaakkoKangasharju

Introduction






Outline

1 Introduction






in the Internet

JaakkoKangasharju

Introduction






SIP Basics

• Application-layer protocol for managing multimediasessions

• . . . nowadays, all kinds of sessions• Designed for extensibility• Proxy-based architecture



in the Internet

JaakkoKangasharju

Introduction






SIP Communication Model

C

P P

C



in the Internet

JaakkoKangasharju

Introduction







C

P P

C

INVITE



in the Internet

JaakkoKangasharju

Introduction







C

P P

C

INVITE

INVITE

INVITE



in the Internet

JaakkoKangasharju

Introduction







C

P P

C

RINGING

RINGING

RINGING



in the Internet

JaakkoKangasharju

Introduction







C

P P

C

OK

OK

OK



in the Internet

JaakkoKangasharju

Introduction







C

P P

CACK



in the Internet

JaakkoKangasharju

Introduction







C

P P

CSession



in the Internet

JaakkoKangasharju

Introduction






Outline

1 Introduction






in the Internet

JaakkoKangasharju

Introduction






The Web Architecture

• The Web an example of a scalable system• What are the principles that allow the Web to scale?

• A number of constraints identified as REST• Not all present in original Web, designed in afterwards



in the Internet

JaakkoKangasharju

Introduction






The Web Architecture

• The Web an example of a scalable system• What are the principles that allow the Web to scale?• A number of constraints identified as REST• Not all present in original Web, designed in afterwards



in the Internet

JaakkoKangasharju

Introduction






REST Primary Constraints

• Client–Stateless-server• Uniform interface• Hypermedia as the engine of application state

⇒ Scalable, flexible, simple⇒ Less efficient



in the Internet

JaakkoKangasharju

Introduction







• Client–Stateless-server• Uniform interface• Hypermedia as the engine of application state⇒ Scalable, flexible, simple

⇒ Less efficient



in the Internet

JaakkoKangasharju

Introduction







• Client–Stateless-server• Uniform interface• Hypermedia as the engine of application state⇒ Scalable, flexible, simple⇒ Less efficient



in the Internet

JaakkoKangasharju

Introduction








C S



in the Internet

JaakkoKangasharju

Introduction








C SP



in the Internet

JaakkoKangasharju

Introduction








C SP G



in the Internet

JaakkoKangasharju

Introduction






REST Services

• How to build services without sessions?

• PUT, POST, and hypermedia• Benefit of statelessness: addresses are transmittable



in the Internet

JaakkoKangasharju

Introduction






REST Services

• How to build services without sessions?• PUT, POST, and hypermedia

• Benefit of statelessness: addresses are transmittable



in the Internet

JaakkoKangasharju

Introduction






REST Services

• How to build services without sessions?• PUT, POST, and hypermedia• Benefit of statelessness: addresses are transmittable



in the Internet

JaakkoKangasharju

Introduction






Outline

1 Introduction



4 Peer-to-Peer ArchitecturesUnstructured P2P NetworksStructured P2P Networks



in the Internet

JaakkoKangasharju

Introduction






Types of Peer-to-Peer Architectures

• Peer-to-peer used for two different applications

• Content search: unstructured P2P• Key-value lookup: structured P2P (distributed hash table)



in the Internet

JaakkoKangasharju

Introduction







• Peer-to-peer used for two different applications• Content search: unstructured P2P

• Key-value lookup: structured P2P (distributed hash table)



in the Internet

JaakkoKangasharju

Introduction







• Peer-to-peer used for two different applications• Content search: unstructured P2P• Key-value lookup: structured P2P (distributed hash table)



in the Internet

JaakkoKangasharju

Introduction






Outline

1 Introduction






in the Internet

JaakkoKangasharju

Introduction






Unstructured P2P Architectures

1 Centralized model: central server for, e.g., indexing• Some but not all problems of client-server

2 Pure model: no central entities• Locating content a problem

3 Hybrid model: hierarchy of peers and super-peers• Combination of centralized and pure



in the Internet

JaakkoKangasharju

Introduction







Centralized P2P

P P

P P

P

P

P

PC



in the Internet

JaakkoKangasharju

Introduction







Pure P2P

P P

P P

P

P

P

P



in the Internet

JaakkoKangasharju

Introduction







Hybrid P2P

P P

P P

P

P

P

P

S

S

S S



in the Internet

JaakkoKangasharju

Introduction






Outline

1 Introduction






in the Internet

JaakkoKangasharju

Introduction






Distributed Hash Tables

• Map identifiers to content, no content-based searching• DHT algorithm tells where content found• Fully decentralized, scalable• Several algorithms in existence



in the Internet

JaakkoKangasharju

Introduction






DHT Example: Chord

1

3

4

7 i start node0 1 31 2 32 4 7



in the Internet

JaakkoKangasharju

Lecture Over

Questions?


Applications and Services in the Internet · Session Initiation Protocol (SIP) Representational...

Documents

Transcript of Applications and Services in the Internet · Session Initiation Protocol (SIP) Representational...