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Write short notes on:
a) N-tier architecture
a) N-tier architecture The N- tier architecture application is distributed among three or more separate computers in a distributed network. The common form of N-tier is the 3-tier application, where the user interface programming is in the users computer and the business logic is in a centralized computer and the data which is needed in the computer that manages the database. It is implied on the client/server program model. If there are more than three distribution levels or tiers involved the additional tiers are usually associated with the business logic tier. It is also referred to as the pulling apart of an application into separate layers or finer grains. One of the best example of this architecture in the web applications is the shopping cart web application. Here the client tier interacts with the user via the GUIs with the application and the application server. In most of the web applications the client is a web browser. The integration tier allows the N-tier architecture to be vendor independent. The business tier is also considered as the integration tier. The encapsulation will allow the application to communicate with the business tier in a way that all the nodes are intelligible. The final application tier is the data tier. It mostly consists of the database servers. The data is kept neutral and independent from the application servers or the business logic. If the data has its own tier it improves the scalability and the performance and as it grows it easily moves to another powerful machine. Benefits of N-Tier Architecture It helps in improving the scalability and supports the cost-efficient application building. It helps in making the applications more readable and reusable. The applications that are made are robust as they have no single point of failure. The tiers function with relative independence. Reusability is important for the web applications.
Authentication and authorization is provided for the security. This allows the web server to restrict the user access which is based on the pre-determined criteria. It helps the developers to build the web applications as it allows the developers to apply their specific skill to that part of a program which best suits their skill set.
Types of Databases
There are various types of databases used for storing different varieties of data:
1) Centralized Database
It is the type of database that stores data at a centralized database system. It comforts the users to access the stored data from different locations through several applications. These applications contain the authentication process to let users access data securely. An example of a Centralized database can be Central Library that carries a central database of each library in a college/university.
Advantages of Centralized Database
● It has decreased the risk of data management, i.e., manipulation of data will not affect the core data. ● Data consistency is maintained as it manages data in a central repository.
- Distributed Database Unlike a centralized database system, in distributed systems, data is distributed among different database systems of an organization. These database systems are connected via communication links. Such links help the end-users to access the data easily. Examples of the Distributed database are Apache Cassandra, HBase, Ignite, etc. We can further divide a distributed database system into:
● Homogeneous DDB: Those database systems which execute on the same operating system and use the same application process and carry the same hardware devices. ● Heterogeneous DDB: Those database systems which execute on different operating systems under different application procedures, and carries different hardware devices.
Advantages of Distributed Database
● Modular development is possible in a distributed database, i.e., the system can be expanded by including new computers and connecting them to the distributed system. ● One server failure will not affect the entire data set.
- Relational Database This database is based on the relational data model, which stores data in the form of rows(tuple) and columns(attributes), and together forms a table(relation). A relational database uses SQL for storing, manipulating, as well as maintaining the data. E.F. Codd invented the database in 1970. Each table in the database carries a key that makes the data unique from others. Examples of Relational databases are MySQL, Microsoft SQL Server, Oracle, etc.
a. Key-value storage: It is the simplest type of database storage where it stores every single item as a key (or attribute name) holding its value, together. b. Document-oriented Database: A type of database used to store data as JSON-like document. It helps developers in storing data by using the same document-model format as used in the application code. c. Graph Databases: It is used for storing vast amounts of data in a graph-like structure. Most commonly, social networking websites use the graph database. d. Wide-column stores: It is similar to the data represented in relational databases. Here, data is stored in large columns together, instead of storing in rows.
Advantages of NoSQL Database
● It enables good productivity in the application development as it is not required to store data in a structured format. ● It is a better option for managing and handling large data sets. ● It provides high scalability. ● Users can quickly access data from the database through key-value.
What is NoSQL and what is a NoSQL database?
NoSQL database technology stores information in JSON documents
instead of columns and rows used by relational databases. To be
clear, NoSQL stands for “not only SQL” rather than “no SQL” at all.
This means a NoSQL JSON database can store and retrieve data using
literally “no SQL.” Or you can combine the flexibility of JSON with the
power of SQL for the best of both worlds. Consequently, NoSQL
databases are built to be flexible, scalable, and capable of rapidly
responding to the data management demands of modern businesses.
The following defines the four most-popular types of NoSQL database:
Document databases are primarily built for storing information as documents, including, but not limited to, JSON documents. These systems can also be used for storing XML documents, for example. Key-value stores group associated data in collections with records that are identified with unique keys for easy retrieval. Key-value stores have just enough structure to mirror the value of relational databases while still preserving the benefits of NoSQL. Wide-column databases use the tabular format of relational databases yet allow a wide variance in how data is named and formatted in each row, even in the same table. Like key-value stores, wide-column databases have some basic structure while also preserving a lot of flexibility. Graph databases use graph structures to define the relationships between stored data points. Graph databases are useful for identifying patterns in unstructured and semi-structured information. Why use NoSQL? Customer experience has quickly become the most important competitive differentiator and ushered the business world into an era of monumental change. As part of this revolution, enterprises are interacting digitally – not only with their customers, but also with their employees, partners, vendors, and even their products – at an unprecedented scale. This interaction is powered by the internet and other 21st century technologies – and at the heart of the revolution are a company’s cloud, mobile, social media, big data, and IoT applications.
How are these applications different from legacy enterprise applications like ERP, HR, and financial accounting? Today’s web, mobile, and IoT applications share one or more (if not all) of the following characteristics. They need to: Support large numbers of concurrent users (tens of thousands, perhaps millions) Deliver highly responsive experiences to a globally distributed base of users Be always available – no downtime Handle semi- and unstructured data Rapidly adapt to changing requirements with frequent updates and new features
- Cloud Database A type of database where data is stored in a virtual environment and executes over the cloud computing platform. It provides users with various cloud computing services (SaaS, PaaS, IaaS, etc.) for accessing the database. There are numerous cloud platforms, but the best options are: ● Amazon Web Services(AWS) ● Microsoft Azure ● Kamatera ● PhonixNAP
It is the database that typically follows the network data model. Here, the representation of data is in the form of nodes connected via links between them. Unlike the hierarchical database, it allows each record to have multiple children and parent nodes to form a generalized graph structure.
- Personal Database Collecting and storing data on the user's system defines a Personal Database. This database is basically designed for a single user.
Advantage of Personal Database
● It is simple and easy to handle. ● It occupies less storage space as it is small in size.
- Operational Database The type of database which creates and updates the database in real-time. It is basically designed for executing and handling the daily data operations in several businesses. For example, An organization uses operational databases for managing per day transactions.
- Enterprise Database Large organizations or enterprises use this database for managing a massive amount of data. It helps organizations to increase and improve their efficiency. Such a database allows simultaneous access to users.
Advantages of Enterprise Database:
● Multi processes are supportable over the Enterprise database. ● It allows executing parallel queries on the system. ●
