1 / 28

Centralized and Client/Server Architecture and Classification of DBMS

Centralized and Client/Server Architecture and Classification of DBMS. Prepared By : Sir Syed Sarmad Ali. Topic To be Covered. Classification of DBMSs, Data modelling using the Entity-relationship model(ER). Syed Sarmad Ali. Centralized and Client-Server Architectures.

benard
Download Presentation

Centralized and Client/Server Architecture and Classification of DBMS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Centralized and Client/Server Architecture and Classification of DBMS Prepared By : Sir Syed Sarmad Ali

  2. Topic To be Covered • Classification of DBMSs, • Data modelling using the Entity-relationship model(ER) • Syed Sarmad Ali

  3. Centralized and Client-Server Architectures • Centralized DBMS: combines everything into single system including- DBMS software, hardware, application programs and user interface processing software. • Syed Sarmad Ali

  4. A physical centralized architecture.

  5. Basic Client-Server Architectures • A server is a system containing both hardware and software that can provide services to the client machines, such as file access, printing or database access. • In general, the client/server architecture was developed to deal with computing environment in which large number of PCs, workstation, file server, printers, database server, web servers, and other equipment are connected via a network. • The idea is to define Specialized Servers with specific functionality. • For example, it is possible to connect a number of PCs or workstation as client to the file server that maintain the files of the client machine. • Similarly, Printer Server dedicated to all the print requests forwarded to this machine. • In this way, resources provided by the specialized servers can be accessed by many client machines. • The client machines provide the user with the appropriate interface to utilize these servers. • Syed Sarmad Ali

  6. Specialized Servers with Specialized functions: • File Servers • Printer Servers • Web Servers • E-mail Servers • Syed Sarmad Ali

  7. Clients: • Provide appropriate interfaces and a client-version of the system to access and utilize the server resources. • Clients maybe diskless machines or PCs or Workstations with disks with only the client software installed. • Connected to the servers via some form of a network. (LAN: local area network, wireless network, etc.) • Syed Sarmad Ali

  8. Logical two-tier client/server architecture • Syed Sarmad Ali

  9. DBMS Server • Provides database query and transaction services to the clients • Sometimes called query and transaction servers • Syed Sarmad Ali

  10. Diskless node • A diskless node (or diskless workstation) is a workstation or personal computer without disk drives, which employs network booting to load its operating system from a server. (A computer may also be said to act as a diskless node, if its disks are unused and network booting is used.) • Diskless workstation • Alternatively referred to as a diskless node, dummy terminal, or dumb terminal, a diskless workstation is a networked computer that provides no local hard drive space or floppy disk drive access. These terminals will have a monitor, motherboard, network card, keyboard, and mouse. This term can also be used to describe any computer that has a hard drive, but is booting and using applications from the network instead of from the local hard drive. This type of computer is often referred to as a hybrid computer or network computer.

  11. Physical two-tier client-server architecture.

  12. Two Tier Client-Server Architecture • In client/server architecture User Interface Program and Application programs can run on the client side. • When DBMS access is required, the program establish a connection to the DBMS(which is on the server side); once the connection is created, the client program can communicate with the DBMS. • A standard called Open Database Connectivity (ODBC) provide an application program interface(API), which allows client-side programs to call the DBMS, as long as both client and server machines have the necessary software installed. • Similarly a related standard is used for the Java Programming language (JDBC), has also been defined. This allow Java client program to access the DBMS through a standard interface. • the architecture is called two tier architecture because the software components are distributed over two system. • Syed Sarmad Ali

  13. Two Tier Client-Server Architecture • A client program may connect to several DBMSs. • Other variations of clients are possible: e.g., in some DBMSs, more functionality is transferred to clients including data dictionary functions, optimization and recovery across multiple servers, etc. In such situations the server may be called the Data Server. Database Management Systems

  14. Three tier Architecture • Many web applications use an architecture called the application server which add an intermediate layer between the client and the database server. • Intermediate Layer called Application Server or Web Server: • The intermediate layer or the middle tier is sometimes called the application server and sometimes the Web Server. • This server plays an intermediary role by providing the rules (procedure and constraints) that are used to access data from the database.

  15. Three tier Architecture • Additional Features- Security: • Improve database security by checking clients credentials before forwarding the request. • encrypt the data at the server before transmission • decrypt data at the client

  16. Logical three-tier client/server architecture. Database Management Systems

  17. Classification of DBMSs • Several criteria are normally used to classify DBMSs. • Data model • Number of users • Number of sites • Cost • Types of access path Database Management Systems

  18. Classification of Data Model • Relational model represents a database as a collection of tables, where each table can be stored as a separate file. • Object model defines a database in terms of objects, their properties, and their operations. • Relational DBMSs have been extending their models to incorporate object database concepts and other capabilities; Object-relational model • Hierarchical model represents data as record types • and also represents a limited type of l:N relationship, called a set type. • Network model represents data as hierarchical tree structures. Database Management Systems

  19. Hierarchical DBMS • Represent data as hierarchical tree structures • Each hierarchy represents a number of related records • A hierarchical database model is a data model in which the data is organized into a tree-like structure. The structure allows representing information using parent/child relationships: each parent can have many children, but each child has only one parent (also known as a 1-to-many relationship). All attributes of a specific record are listed under an entity type.

  20. Network DBMS • Resembles hierarchical model • Represent data as record types • Collection of records in 1:N relationships • The network model is a database model conceived as a flexible way of representing objects and their relationships. Its distinguishing feature is that the schema, viewed as a graph in which object types are nodes and relationship types are arcs, is not restricted to being a hierarchy or lattice.

  21. The schema of Figure 2.1 in network model notation Database Management Systems

  22. Relational DBMS • Represent database as collection of tables • Each table can be stored as separate file

  23. Relational DBMS (cont.) • Relational schema • representation of relational database’s entities, attributes within those entities, and relationships between those entities • Relational table • Stores a collection of related entities

  24. Object Oriented Model • Represent database in terms of object, their properties and their operations. • Objects with same structure and behavior belongs to same class. • Classes are organized into hierarchies. • Operations of each class are called methods.

  25. Object relational DBMS • Relational DBMS are extending their models by incorporating object database concepts resulting in object-relational or extended relational systems.

  26. Number of users • Single-user systems support only one user at a time and are mostly used with personal computers. • Multiuser systems, which include the majority of DBMSs, support multiple users concurrently. Database Management Systems

  27. Number of sites • A DBMS is centralized if the data is stored at a single computer site. • A distributed DBMS (DDBMS) can have the actual database and DBMS software distributed over many sites, connected by a computer network. • Homogeneous • Heterogeneous • Federated or Multidatabase Systems Database Management Systems

  28. Types of the access path • One well-known family of DBMSs is based on inverted file structures. Finally, a DBMS can be general purpose or special purpose. • Online transaction processing (OLTP) systems, Database Management Systems

More Related