Unit 5- Understanding Middleware(5hr)

5th Semester

Define Middleware . 2014
Middleware is software that runs between client and server processes. It is the “GLUE” between the client and server, which makes it possible for them to communicate to each other.  It delivers secure and transparent services to users.
Some of the middleware services are :-

  • Remote Data Access (RDA)
  • Remote procedure calls (RPCs)
  • Message-oriented middleware (MOM)
  • Distributed transaction processing (DTP)

General Characteristics

  •  Easier to design, develop, & maintain
  •  reliability, efficiency throughput
  • Secure, dynamic, adaptable, scalable, available
  • Flexible, portable, maintainable, reusable

Functions

  • Data generation
  • validation
  • Authorization,
  • conversion
  • Re-formatting
  • Transaction mapping and logging.

Main types of Middleware

  • DCE (Distributed Computing Environment)
  • MOM (Message Oriented Middleware) : communication via message exchange
  • Transaction processing (TP) Monitors : two-phase commit for distributed transactions

1.  DCE (Distributed Computing Environment)
DCE (Distributed Computing Environment) is an industry-standard software technology for setting up and managing computing and data exchange in a system of distributed computers. DCE is typically used in a larger network of computing systems that include different size servers scattered geographically. DCE uses the client/server model. Using DCE, application users can use applications and data at remote servers.
DCE is based on three distributed computing models:
Client/server :-A way of organizing a distributed application
Remote procedure call :- A way of communicating between parts of a distributed application
Shared files :- A way of handling data in a distributed system, based on a personal computer file access model.
DCE architecture:
DCE architecture:को लागि तस्बिर परिणाम
The DCE services include:
Remote procedure call (RPC) — which facilitates client-server communication, so that an application can effectively access resources distributed across a network. 2017
Security Service — authenticates the identities of users, authorizes access to resources on a distributed network, and provides user and server account management.
Directory Service — provides a single naming model throughout the distributed environment.
Time Service — synchronizes the system clocks throughout the network.
Threads Service — provides multiple threads of execution capability.
Distributed File Service — provides access to files across a network.
 

MOM (Message Oriented Middleware) : communication via message exchange

MOM is a specific class of middleware that supports the exchange of general-purpose messages in a distributed application environment. Data is exchanged by message passing and/or message queuing supporting both synchronous and asynchronous interactions between distributed computing processes. The MOM system ensures message delivery by using reliable queues and by providing the directory, security, and administrative services required to support messagin
mom based systemको लागि तस्बिर परिणाम
MOM – Messaging Models

  • Point-to-Point Model 
  • Publish/Subscribe Model

Transaction processing (TP) Monitors : two-phase commit for distributed transactions

A transaction processing monitor (TPM) is a program that monitors transactions from one stage to the next, ensuring that each one completes successfully; if not, or if an error occurs, the TM Monitor takes the appropriate action. A transaction processing monitor’s main purpose/objective is to allow resource sharing and assure optimal use of the resources by applications i.e. Load Balancing.
A Transaction Processing System (TPS) is a type of information system that collects, stores, modifies and retrieves the data transactions of an enterprise.

Features

Rapid Response: The response time of a transaction processing system (TPS) is important because a business cannot afford to have their customers waiting for long periods of time before making a transaction.

Reliability: A good TPS must be very reliable because if it were to break down businesses could lose a huge portion of revenue because customers would not be able to purchase their products.

Inflexibility: The TPS must work the same way for every transaction as long as the TPS is being used. The formality and structure should never change.

Controlled processing: The TPS must be able to allow authorized employees to be able to access it at any time.

Types of Model

  • Process per client model – instead of individual login session per terminal, server process communicates with the terminal, handles authentication, and executes
  • Many-server single-router model – multiple application server processes access a common database; clients communicate with the application through a single communication process that routes
  • Many server many-router model – multiple processes communicate with
    • Client communication processes interact with router processes that route their requests to the appropriate
    • Controller process starts up and supervises other

Define Groupware & Groupware server 2013

Groupware refers to programs that help people work together collectively while located remotely from each other.

  • Groupware server is software that allows the collaboration of users, irrespective of location through the internet or intranet to work together in an atmosphere which is virtual. The number of clients that need to be connected to this server mostly depends on the scope and nature of the project

Programs that enable real time collaboration are called synchronous groupware. Groupware services can include the sharing of calendars, collective writing, e-mail handling, shared database access, electronic meetings with each person able to see and display information to others, and other activities. Sometimes called collaborative software.

Some product examples of groupware include Lotus Notes and Microsoft Exchange, both of which facilitate calendar sharing, e-mail handling, and the replication of files across a distributed system so that all users can view the same information
Benefits and Features of Groupware

  • Groupware allows both on-site workers and geographically dispersed team members to collaborate with each other over the internet .
  • A centralized place for saving and accessing documents or files  shared calendars and task management, and communication tools, from instant messaging and video conferencing to white boards and message boards.
  • Groupware apps serve as a virtual office hub–everything is stored, shared, and documented in one place, which makes finding information and sharing data so much easier
  • Easy file sharing, collaboration, and communication over projects with remote clients.

Approaches to Database Connectivity 2015

ODBC stands for Open Database Connectivity.  Open Database Connectivity (ODBC) is a standard application programming interface (API) for accessing database management systems (DBMS) . The designers of ODBC aimed to make it independent of database systems and operating systems.  
Java Database Connectivity (JDBC) is an application programming interface (API) for the programming language Java, which defines how a client may access a database.
 
odbc vs jdbsको लागि तस्बिर परिणाम
1 marks:- 2014,2015

Database languages are used to read, update and store data in a database.

Types:-

  • Data Definition Language (DDL)
  • Data Manipulation Language (DML)
  • Data Control language (DCL)
  • Transaction Control Language(TCL)