MOBILE DATA BASES:

-
  • Mobile Database' is either a stationary database that can be connected to by a mobile computing device - such as smart phones or PDAs - over a mobile network, or a database which is actually carried by the mobile device. This could be a list of contacts, price information, distance travelled, or any other information.
  • Mobile database systems have to be adapted to the limited resources of current mobile devices.
  • They are small-footprint databases, which use special replication and synchronization algorithms for the communication (up and download) with a centralized, consolidated and hard-wired database.
  • A mobile database uses wireless technology to allow mobile computers to connect to its system.
  • The database consists of a client and server that connect to each other over awireless network. Due to the vulnerability of wireless network signals, a cache of activity is maintained to ensure that sensitive information can be recovered.
  • A mobile database is used to provide remote access to information that authorized users may need to obtain on a moment's notice.
  • Mobile or cloud computing usually consists of three components.
    • Base Stations: The Base stations are responsible for controlling the communication signals that need to be passed from one host to another. A base station receives and sends information and often comes in the form of some type of Wireless router.
    • Hosts: They  are responsible for handling the actual transactions that occur within a mobile database. They are sometimes referred to as "fixed," since hosts do not typically change locations within the network. In order to process database requests, hosts use servers or software applications in order to access the data that is needed.
    • Mobile unit:  These are the portable computers, phones and other devices that request information from the database. Rather than communicating directly with the database server, mobile units route their requests through the base stations.
  • The various issues associated with mobile databases include the following:
    • The relative unreliability of connections: The access between central servers and the mobile system may be unreliable at times.The disconnections that may occur can disrupt a query being performed and as a result, prevent or slow query response.
    • The limitations on storage capacity: Due to the storage limitation of mobile computers, it is thus difficult to create replicas of large databases on such devices, particularly on handheld devices such as PDAs, which are the current focus of our work.
    • The security and privacy issues created when a computer is in a mobile environment.
  • Mobile database functionalities include the following
    • Query processing and optimization
    • Data Replication schema
    • Concurrency controls
    • Transaction support
    • System recovery

Comments

Post a Comment

Popular posts from this blog

Pentium microprocessors

-
Image
A 32-bit microprocessor introduced by Intel in 1993. It contains 3.3 million transistors. Since 1993, Intel has developed the Pentium III and more recently the Pentium 4 microprocessors.   Pentium III Pentium III Mainboard Layout Intel builds on the technology it developed with the Pentium II microprocessors.  The Pentium III processor comes with a Synchronized Dynamic Random Access Memory (SDRAM), allowing for an extremely fast transfer of data between the microprocessor and the memory. 70 new instructions, called Streaming SIMD Extensions, enhance multimedia and 3D performance.  Launched February 1999 - Available in speed levels of 450, 500, 550, and 600MHz. 32KB of Level 1 Cache (operating at CPU's full core speed). 512KB of Level 2 Cache (operating at ½ of CPU's core speed). 100 MHz bus speed. The branch prediction/recovery pipeline was doubled to include 10-stages from the P-II.   Pentium IV The next generation of microprocessors from Intel. Pe
Read more

Design and Management of Computer Networks Running Notes

-
Architecture and Design Process Hierarchy and Inter-connectivity Network Supportability ------------------------------------------------------------------------------------------- Service Description pdf Service characteristics pdf Service Levels pdf System Components and network services pdf Service Requests and Requirements pdf Service Offerings pdf Service Matrices pdf Performance Characteristics pdf for running notes Download here ------------------------------------------------------------------------------------------- Types of user requirements pdf Timeliness Interactivity Reliability Presentation Quality Adaptability Security Affordability Functionality Supportability Future growth Requirement Analysis pdf The need for Requirement Analysis User Requirements pdf for running notes Download here -------------------------------------------------------------------------------------------  Applic
Read more

ONE DIMENSIONAL RANDOM VARIABLES: Handwritten notes

-
Properties of probability Distribution Function Expectation Value For the following problem by using Find the distribution function of x? What is the smallest value of x? for which probability P(X<=x)>0.5 for more click here ---------------------------------------------------------------------------------------------------------------- Continues Random Variable           We call the distribution function as probability density function f(x). Properties of probability density function.  click here ---------------------------------------------------------------------------------------------------------------- Moment Generating Function (MGF) Properties Additional property in MGF  for notes click here ---------------------------------------------------------------------------------------------------------------- Bernoulli Trial       For a single trail with only two possible results.  Example: Tossing a coin. p=1/2, q=1/2 p + q = 1 p = q
Read more