CHAPTER ONE
INTRODUCTION
Progress in communication and database technologies has changed the user data processing environment. The present data processing environment can be described by applications that require processing to be performed at multiple sites, also need to access data located at multiple sites of a network. A multi database system (MDBS) is software that runs on top of the individual database management systems (DBMSs) which is maintained at each site. Transactions in MDBS may be either local or global. Local transactions are directly submitted to individual local DBMS (LDBMS) and they access only local data. A global transaction consists of one or more sub transactions which may access data from more than one LDBMS. Local transaction and sub transaction execution is controlled by LDBMS whereas global transaction execution is controlled by MDBMS. To ensure natural integration of several LDBMSs, MDBMS should preserve its local autonomy [1].Transaction management; one of the many issues in MDBS design raises problems like concurrency control, commitment, and recovery. These challenges have been met earlier with an assumption that failures don’t occur. In a failure free environment strict two-phase locking assures global atomicity. However that cannot be applied incase of a sub transaction failure. Hence a global atomic commitment protocol that can handle failures is necessary. Proposed a global atomic commitment protocol in presence of failures but at the cost of violation of local autonomy. The approach taken in [10] achieves global atomicity and can recover from failures. In this protocol a centralized transaction manager (TM) receives global transactions, submits sub transactions to the appropriate sites via agents. AGENT is a component of MDBS that runs on each site; AGENTS after receiving sub transactions from the transaction manager perform the transaction and send the results back to TM. We have presented a unique proof-of-concept, a JAVA API for an agent based transaction manager that preserves global atomicity. It provides a user friendly interface through which reliable atomic commitment protocol for global transaction execution in multi database environment can be visualized. . We demonstrated with three different test case scenarios how the protocol works. This helps in further research in this area where atomicity of transactions can be verified for protocol correctness.
1.1 STATEMENT OF THE PROBLEM
The management of Airline in Nigeria has over the years attracted poor patronage as a result of errors inherent in the system. It is no longer a new thing that loss of customers’ goods is now the order of the day, the reasons are not far-fetched. Due to this manual procedure involved in Airline management, clients have no other option than to be at the mercy of these error prone procedures. Members of staff of AERO CONTRACTORS one to the registered travelling agencies and a subsidiary of plc cannot provide their goods that is the nature of the method used in calculating the tonnage to know the amount of money to pay as Airline fees. The method of information storage in the company is poor. This limits the number of official documents accessible by the customers because the system is not capable of managing old items of information which could be of use to be customer of anytime. There is little or no security control system where the customers’ goods, document and classified information of the customer could be safe guarded from unauthorized access.
SIGNIFICANT OF STUDY
To provide efficient, effective and timely travel service nationally and internationally. Our main objective is to provide efficient, effective, timely service to all our customers. This is done by assisting our customers in planning their trip and obtaining best value. Periodically we introduce innovative services and products than currently exist in the Nigerian travel market and develop a good approach to serving our customers.
