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1）A distributed database is a database in which not all storage devices are attached to a common processor. It may be stored in multiple computers, located in the same physical location; or may be dispersed over a network of interconnected computers.

2）Two processes ensure that the distributed databases remain up-to-date and current: replication and duplication.

1. Replication involves using specialized software that looks for changes in the distributive database. Once the changes have been identified, the replication process makes all the databases look the same. The replication process can be complex and time-consuming depending on the size and number of the distributed databases. This process can also require a lot of time and computer resources.

2. Duplication, on the other hand, has less complexity. It basically identifies one database as a master and then duplicates that database. The duplication process is normally done at a set time after hours. This is to ensure that each distributed location has the same data. In the duplication process, users may change only the master database. This ensures that local data will not be overwritten.

Both replication and duplication can keep the data current in all distributive locations

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1(c) what is independence and what is it's function in transaction 

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1(c) what is independence and what is it's function in transaction 

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Lee Ying Xuan
Induja

Independence means freedom from the control, influence,support, aid, or the like, of others.

The functions of independence in transaction are:
-if several transactions are executed concurrently the result must be the same
-the data use during the execution of the transaction cannot be used by the second transaction until the first one is completed

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computer program which manages access to a centralized resource or service in a network.
You'll need additional physical hardware, of at least the minimum amount required by your Operating System and any other applications that run on the server.

Each server must have a minimum of:

64 GB memory

300 GB hard drive

4 CPU cores

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1(b). What is consistency and what is its function in transaction? 

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1(b). What is consistency and what is its function in transaction? 

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Meaning consistency is Data or information is in a consistent state when a transaction starts and when it ends

Function in transaction is ensure only valid data that following all rules is written in database

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1) what does it means?
Client and servers describe how a server provides resources and services to one or more clients.

-Client: initiates comunication
-server: send information’s back to client

2) how does it work?
a client requests a connection to a server, the server can either accept or reject the connection. the server maintains a connection with the client.

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2b.) Conceptual Layer & Example ( Boon Keat & Kang Zhuang

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2b.) Conceptual Layer & Example ( Boon Keat & Kang Zhuang

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Conceptual layer include only the main concepts and the main relationship among them.This level describes the structure of the whole database for a group of users by focusing on describing entities, data type, relationships and constraints. To make it simple, conceptual layer is a map of concepts and the relationship used for database. The complexity increases from conceptual to logical to physical. This is why we always first start with the conceptual data model so we understand at high level what are the different entities in our data and how they relate to one another.

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Hajar & Hafizah

1. Media Stream is video or audio content sent in compressed from over the Internet and played immediately.
2. Live multimedia is the delivery of Internet content in real-time.
3. Continuous queries is a query over a stream executes continuously over streaming data.

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2a ( External Layer )
External layer user' view of the database

Example:
1. 3-tier architechture
Is a client server architecture in which the functional process logic, data access, computer data storage and user interface are developed maintained as independence moduls on separate platforms.

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4(b) what are the characteristics of server?

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4(b) what are the characteristics of server?

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Soo Jun Hui & Chong Hooi Khee

- Server response time is important
- Network is fundamental
- Real-time delivery
- Accept connection from a large number of client
- Share database to multiple user

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1(d) what is durability and what is it's function in transaction 

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1(d) what is durability and what is it's function in transaction 

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Chrishelly & Nadzmi

Durability is something that ensures transaction are saved even when the transaction ends abnormally.
The function of durability in transaction
1) save the transaction
2) restore the data as before it crashed
3) survive from failure

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Ad (2) Super server, what is it used for?

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Ad (2) Super server, what is it used for?

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Fathin & Rawdhah

Super server is a daemon used for managing other servers. It is a high speed network server with very large RAM and disk capacity. In addition, it is commonly used to handle server loads and supports multiprocessing.

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Internal layer and example

Hijrah & Mayjing

-also known as physical layer
-internal layer describes the physical storage structure of data in database.
-physical storage is properly designed to increase data processing efficiency and minimise the time required by users to interact with the information system
-in the internal layer have internal schema
- internal schema describe details of how data is stored
- the internal layer only for computer view

-At lowest level, it is stored in the form of bits with the physical addresses on the secondary storage device.
-At highest level, users can be viewed in the form of files
-example: employee database

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Yuzeir
Hisam

What is scalability?
-factor causing

1. Definition
Scalability is an attribute that describe the ability of a process, network, software or organization to grow and manage increase demand.

Administrative Scalability
Functional Scalability
Geographic Scalability

As example for a software, that is described as scalable has an advantage because it can adapt to the changing, needs or demand of the user. One of the example software is antivirus.

2. Factor Causing

- To satisfy certain group of user
- The increase number of user
- To influence the user about the capability

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1) Its means, a centralized database is a database that is located, stored, and maintained in a single location. This location is most often a central computer or database system. This means, all data will be stored in one location and the system does not interact with other computer system.
2) Multiple users or client workstations can work simultaneously on a centralized database system using the client or server configuration.

Advantage of Centralized
1)The data redundancy is minimal in the centralised . All the data is stored together and not scattered across different locations. So, it is easier to make sure there is no redundant data available.
2) Since all data in a place , there can be stronger
Security measures around it, So the centralised database is much more secure
Meena
Gunesh

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Sow Li Ling & Tiew Hui Min

1. Streaming is a method or technique which is used in transferring data. To make sure the process of data sent to a device over the Internet in stable and continuous.

2. Audio and video materials especially for immediate processing or playback.

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5b (what is the advantages & disadvantages of peer to peer network? 

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5b (what is the advantages & disadvantages of peer to peer network? 

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Chin Man Wai
Yeoh Kim Zhen

2. Advantages

1) much easier to set up than a client server network
2) does not need an expensive server
3) if one computer fails, it does not disrupt any part of the network.

Disadvantages
1) No centralized server is available to manage and control the acess of data.
2) There is little or no security besides the permissions.
3) Slow down the performance for the user.

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Wan nur syafiqah & Siti nurafifa

Super server
Or called service dispatcher is a type of daemon run generally on UNIX-like systems.
Daemon is a network service implemented as daemon Linux System.
Functions for this super server are used for managing other servers.
Benefits
Active at all times.
No system resources a wasted.

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Quality of service is the description or measurement of the overall performance of a service such as computer network service, particularly the performance seen by the users of the network.

To measure the quality of service, there are several aspects of the network service are often concidered such as packet loss, throughput and jitter.

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5(a) What is peer to peer network? What is its characteristics?

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5(a) What is peer to peer network? What is its characteristics?

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Peer to peer network is a network that have no central server. All peers work as both client and server
Characteristics:
- All peers participate equally in a network
- All peers can share content with other peers
- If one peer disconnected, the network will not be interrupted

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Nur eleena & Nur adilah

What is atomicity and what is its function in transaction

Atomicity is an indivisible and irreducible series of database operations such that it will all happen or nothing will happen.

Function:
To ensure the data will not lose. So it protect the user losing money due to a failed transaction

Example :
the person make a transaction money from account A to account B, if there is a failure due to the atomocity, the money will successfully transferred to account B or will not transferred to account B and stay remains in account A.

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Aliaa & Sakinah

What is the issues in quality of service?

1) optimization
2) parallel processing
3) partition