 Hello everyone. This is Supriya Ambarkar from Walshan Institute of Technology. So, Lapur, today we are going to discuss a topic on fundamentals of distributed system, which includes what is distributed system, how it works, its architecture, its characteristics, its different types, etc. The learning outcome. At the end of this session, students will be able to explain the different types of distributed system. Also, students will be able to state the different challenges of distributed systems. Here, first we will see the introduction. The distributed system is a network that consists of autonomous computers that are connected using a distribution middleware. So, they help in sharing different resources and capabilities to provide users with a single and integrated coherent networks. So, features such as there is a no shared memory concept in terms of what the message best communication is there. Each runs its own local memory. It's having a heterogeneity in nature. Now, we will continue with the particular slide. As distributed system can be presented as a single system image view. It having a continuous availability. It's having easily expandable. It's supported by the middleware architecture. Now, we will see the details of the computer architecture. Here, the net result of the advancements in the price performance ratio has now changed to the use of interconnected multiple processors in place of a single high-speed processor. So, the computer architecture consisting of interconnected multiple processors which are of two types that is an tightly coupled systems and loosely coupled systems. Now, we will see the details of this particular architectural diagram. First tightly coupled system means what? Here, the single system wide primary memory which we want to say as an address space that is shared by all the processors. That means the value suppose 200 to the memory location of x then any other processor subsequently read from the location of x will get back the value 200 that is in terms of tightly coupled. A loosely coupled system here the processor do not share the memory and each processor has its own local memory. Suppose if a processor writes the value 200 to the memory location x this write operation will only change the contents of its local memory and will not affect the contents of the memory of any other processor. So, generally tightly coupled systems are referred to as a parallel processing systems and loosely coupled systems are referred to as a distributed computing systems. Now, we will see the different types of distributed systems. First distributed computing systems. Second distributed information systems. Third distributed pervasive systems. The details of this particular systems are as follows. The distributed computing systems include grade computing and cluster computing. Distributed information systems include enterprise application system, transaction processing systems. Third distributed pervasive system includes sensor networks, home systems, electronics health care systems and etc. So, these are all about the different types. Now, we will see the distributed system diagram. A distributed system organized as a middleware. The middleware layer runs on all machines and offers a uniform interface to the system. Here in this diagram we are having four network computers and three applications. Application B is a distributed across computer 2 and 3. Each application is offered the same interfaces. Distributed system provides a means for components of a single distributed application to communicate with each other, but also to let different applications communicate. It also hides the differences in hardware and operating system from each application. So, this is all about this particular distributed system diagram. Now, we will see the gaining popularity of a distributed system. First, it is an inherently distributed application. Means what? The several applications are inherently distributed in nature, that is the airline reservation system and etc. Then second gaining popularity in terms of what? Information sharing among distributed users means persons to person sharing information over a great distance is possible. Third resource sharing. Sharing of a software resources such as software libraries, databases are allowed. As well as hardware resources such as printers, hard disk are allowed. Then fourth one is a better price performance ratio is there. So, it is one of the important reason why gaining popularity of a distributed system. Then shorter response times and the higher throughput is there. The two commonly used performance metrics are response times and the throughput. So, this is also one of the important gaining popularity. Next one is an higher reliability. A system should be reliable means it prevents the loss of information even in the event of a component failure. So, this is one of the gaining popularity. Then next one is an extensibility and incremental growth. Distributed systems are capable of incremental growth. So, it is possible due to gradually extend the power and functionality after adding the additional resources. So, it is also the important gaining popularity. Last one is a better flexibility in meeting the user needs. So, it almost meet all the user needs in terms of the gaining popularity. Next we will see the different issues while designing the distributed system. Transparency, reliability, flexibility, performance, scalability, heterogeneity, security, then emulation in existing operating system these are all the issues. We will see one by one. In terms of the transparency, the main goal of a distributed system is to make the existence of multiple computers invisible. Means it should be the transparent one and provide a single system image view to the particular user. So, this is the first. Then in terms of reliability, distributed systems are expected to be more reliable than centralized system due to the multiple instances of resources. Third flexibility, so it is an important feature for the open distributed systems, performance. Its performance must be at least as good as the centralized system. So, it is an expected. Next is in scalability. It refers to the capability of a system to adapt to the increased service load. So, this is in terms of scalability. Heterogeneity means it consists of interconnected sets of dissimilar hardware or software systems. We want to manage those systems. So, it is an heterogeneity. So, in terms of security, maintaining security in distributed system is more difficult than the centralized system. So, it is a challenging issue. Emulation in existing operating system means for commercial success, it is a very important issue. So, we have to emulate the particular existing operating system. Now, we will see the characteristics of a centralized system. Here in centralized system, one component with non-autonomous parts are there. So, here the components may be shared by users all the times. All resources are accessible. Software ends in a single process. Here the single point of control is there. Single point of failure might be occur. So, these are all about the centralized system. Now, we will see the characteristics of distributed system. The distributed systems are the multiple autonomous components. May going together, it forms a distributed system. So, might be components are not shared by all the users. Software runs in a concurrent processes on different processors. It may be possible. It having a multiple points of control. It having a multiple points of failure also. Now, pause the video and write down your answer. State the different challenges of distributed systems. Here the different challenges of distributed systems include heterogeneity, openness, security, failure handling, scalability, transparency, reliability, performance. We will see one by one. Heterogeneity. Distributed system is a heterogeneous in nature. So, coordination and resource sharing can be difficult if proper protocols or policies are not in place. So, this is about the heterogeneity. For openness, making the network easier to configure and modify. So, this is one of the challenge for the distributed system. Security. It is a big challenge in a distributed environment, especially when using the public networks. For failure handling, it could be tough when the distributed model is based on the unreliable components. Then in terms of the scalability, distributed system should be scalable with respect to the geography, administration or the in terms of science. In terms of transparency, achieving the image of a single system image without concealing the details of the location, access, migration, concurrency, failure, relocation, persistence assistance and resources to the users. So, this is also the important challenges. Then seventh one is in reliability. As compared to the single system, a distributed system should be highly capable of being secure, consistent and have a high capability of masking the errors. So, it is an reliable one. Performance challenge in terms of as compared with the other models, distributed models are expected to give a much wanted boost to the performance. So, these are the some challenges which will be required while designing a distributed system. We have to think over that. So, here the ultimate goal of an ideal distributed computing, which is to the maximize the performance by connecting users and IT resources in a cost effective, transparent and reliable manner. So, then we are able to say that the system is an ideal distributed system when we are achieving these all challenges. These are the few references which I have referred for this particular topic. Thank you one and all.