NETWORK OPERATING 51 SYSTEM www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MIDDLEWARE OPERATING 52 SYSTEM • Software above the operating system but below the application program • Middleware refers to the software that is common to multiple applications and builds on the network transport services to enable ready development of new applications and network services. • CORBA, DCOM, Java RMI, Grid www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MIDDLEWARE OPERATING 53 SYSTEM www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MIDDLEWARE 54 Middleware is computer software that provides services to software applications beyond those available from the operating system. Middleware makes it easier for software developers to perform communication and input/output, so they can focus on the specific purpose of their application. Middleware is the software that connects software components or enterprise applications. Middleware is the software layer that lies between the operating system and the applications on each side of a distributed computer network . www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
WHAT IS 55 MIDDLEWARE? Layer between OS and distributed applications. Hides complexity and heterogeneity of distributed system . Software that functions as a conversion or translation layer. Bridges gap between low-level OS communications and programming language abstractions. Provides common programming abstraction and infrastructure for distributed applications. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MIDDLEWARE 56 APPLICATIONS Middleware services are sets of distributed software that provide a more functional set of APIs than does the operating system and network services. Locate transparently across the network, providing interaction with another application or service. Be independent from network services. Be reliable and available. Scale up in capacity without losing functionality. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MODELS OF 57 MIDDLEWARE Remote Procedure call: • It is one of the successful middle ware models used in modern distributed applications for communication. • It uses local call to call a procedure resides on the remote machine to get the result. • Hidden communication is done between client and server. • For eg If a user wants to get the sum of two numbers stored on remote server by using local method call, the user calls method with parameters, in turn server receives a RPC call from the client and returns the appropriate result to the client. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MODELS OF 58 MIDDLEWARE Remote Procedure call: • Therefore, though the method was executed remotely it appears like a local to the called machine. • This is a synchronous technology where both the client and server should be present during the communication. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MODELS OF 59 MIDDLEWARE Message oriented Middleware(MOM): • It is another model used to send and receive the communication messages between clients and servers. • It uses data structures like queue to store and retrieve messages. • When the client is sending the messages faster than the receiver receiving it or the client is sending the message when the receiver is not available. So it uses queuing mechanism between the client and server to avoid the message been misplaced. • It is asynchronous mechanism where messages can be sent even though the receiver is not available • For eg Email system www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MODELS OF 60 MIDDLEWARE • Distributed Object Technology • The distributed object technology has changed the scope of middleware technologies to one step up where objects are distributed to the remote server to facilitate the client. • Eg RMI and CORBA • The distributed object mechanism hides the communication interfaces and their details to provide access to the remote object efficiently. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MODELS OF 61 MIDDLEWARE Remote Method Invocation: • In this objects are distributed and located by using the RMI registry. • The client can access remote objects by using the interfaces. • It didn’t support the concept of heterogeneity and is compatible with java platform only. Common object request broker architecture(CORBA)- • It is one of the most popular distributed object technologies where objects can be accessible from remote location through ORB. • Server and client communicate with each other through object request broker bus. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MODELS OF 62 MIDDLEWARE Remote Method Invocation: • To map the semantics of objects and fetch the appropriate object an interface definition language is used. • It is evolved with service based middle ware where service models are used. • In service model, the services are published by the service providers and consumed by the service consumer. • eg Service oriented Architecture (SOA) www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
CLIENT - SERVER 63 MODEL The Client-server model is a distributed application structure that partitions task or workload between the providers of a resource or service, called servers, and service requesters called clients. In the client-server architecture, when the client computer sends a request for data to the server through the internet, the server accepts the requested process and deliver the data packets requested back to the client. Clients do not share any of their resources. Examples of Client-Server Model are Email, World Wide Web, etc. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
HOW CLIENT - SERVER MODEL 64 WORKS? Client: When we talk the word Client, it mean to talk of a person or an organization using a particular service. Similarly in the digital world a Client is a computer (Host) i.e. capable of receiving information or using a particular service from the service providers (Servers). Servers: Similarly, when we talk the word Servers, It mean a person or medium that serves something. Similarly in this digital world a Server is a remote computer which provides information (data) or access to particular services. So, its basically the Client requesting something and the Server serving it as long as its present in the database. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
HOW CLIENT - SERVER MODEL 65 WORKS? www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
HOW CLIENT - SERVER MODEL 66 WORKS? • Advantages of Client-Server model: • Centralized system with all data in a single place. • Cost efficient requires less maintenance cost and Data recovery is possible. • The capacity of the Client and Servers can be changed separately. • Better price/performance on client machines • Ability to use familiar tools on client machines • Client access to remote data (via standards) www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
HOW CLIENT - SERVER 67 MODEL WORKS? • Disadvantages of Client-Server model: • Clients are prone to viruses, Trojans and worms if present in the Server or uploaded into the Server. • Server are prone to Denial of Service (DOS) attacks. • Data packets may be spoofed or modified during transmission. • Phishing or capturing login credentials or other useful information of the user are common and MITM(Man in the Middle) attacks are common. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MULTIPLE CHOICE QUESTIONS 68 1) In distributed system, each processor has its own ___________ a) local memory c) both local memory and clock b) clock d) none of the mentioned 2 ) If one site fails in distributed system then ___________ a) the remaining sites can continue operating c) directly connected sites will stop working b) all the sites will stop working d) none of the mentioned 3) Network operating system runs on ___________ a) server c) both server and every system in the network b) every system in the network d) none of the mentioned 4) Which technique is based on compile-time program transformation for accessing remote data in a distributed-memory parallel system? a) cache coherence scheme c) remote procedure call b) computation migration d) message passing Answers:1) c) 2)a) 3)a) 4)b) www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
MULTIPLE CHOICE QUESTIONS 69 5 ) Logical extension of computation migration is ___________ a) process migration c) thread migration b) system migration d) data migration 6) Processes on the remote systems are identified by ___________ a) host ID c) identifier b) host name and identifier d) process ID 7) Which routing technique is used in a distributed system? a) fixed routing c) dynamic routing b) virtual routing d) all of the mentioned 8) The capability of a system to adapt the increased service load is called ___________ a) scalability c) capacity b) tolerance d) none of the mentioned Answers: 5) a) 6) b) 7) d) 8)a) www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
SUMMARY 70 A distributed system is a network that consists of autonomous computers that are connected using a distribution middleware. They help in sharing different resources and capabilities to provide users with a single and integrated coherent network. The Client-server model is a distributed application structure that partitions task or workload between the providers of a resource or service, called servers, and service requesters called clients. In the client-server architecture, when the client computer sends a request for data to the server through the internet, the server accepts the requested process and deliver the data packets requested back to the client. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
FREQUENTLY ASKED QUESTION 71 Q:1 Define Distributed System? Ans : A distributed system is a network that consists of autonomous computers that are connected using a distribution middleware. For further details please refer to the slide no. 5 and subject SLM unit 4. Q: 2 List the Characteristics of distributed system? Ans : For further details please refer to the slide no. 6 and subject SLM unit 4. Q: 3 Explain the advantages and disadvantages of distributed system? Ans : For further details please refer to the slide no. 9 and subject SLM unit 4. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
FREQUENTLY ASKED QUESTIONS 72 Q: 4 Explain Client – Server model in detail? Ans : The client-server architecture is the most common distributed system architecture. For further details please refer to the slide no. 17 and subject SLM unit 4. Q: 5 Explain Hardware Concepts in Distributed in System? Ans : For further details please refer to the slide no. 37 and subject SLM unit 4. Q: 6 What do you mean by Middleware? Ans: Middleware is computer software that provides services to software applications beyond those available from the operating system. For further details please refer to the slide no. 54 and subject SLM unit 4. www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
REFERENCES 73 M.R. Bhujade, “Parallel Computing”, 2nd edition, New Age International Publishers 2009. Andrew S. Tanenbaum and Maarten Van Steen, “Distributed Systems: Principles and Paradigms, 2nd edition, Pearson Education, Inc., 2007, ISBN: 0-13-239227-5. George Coulouris, Jean Dollimore, Tim Kindberg, “Distributed Systems: Concepts and Design” (4th Edition), Addison Wesley/Pearson Education. design”, IEEE computer Pradeep K Sinha, “Distributed Operating Systems: Concepts and society press www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
74 THANK YOU www.cuidol.in Unit-4 (MCA635) All right are reserved with CU-IDOL
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