ON-LINE PROCESSING
The word on-line processing means we get immediate response from the system as soon as input is given to the system or we can say waiting period is less to get the output.
It is different from batch processing where master file is not updated immediately like interest calculation of bank accounts where the response from the server is not required immediately it can be done once at the end of the day .
Now think about another application i.e. Railway booking as soon as ticket reserved by anyone then and then server need to be updated because if it is not done we get wrong information from the system. suppose booking a particular train ,100 tickets are available if 5 ticket is booked by a person now available ticket is 100-5=95 right now think for this particular application whether batch processing is perfect or we should apply on-line processing of course we should go for on-line processing as because we need to update the server immediately as soon as ticket booked by a person.
The system through which on-line transaction is processed is called on-line transaction processing (OLTP) systems.
Now suppose 5 persons from 5 different places trying to book the ticket of the same train at same time then what happened master file need to be updated at the same time but if this occurred we get wrong data or record from the server here we can apply the concept of record locking.
In this process the record need to be locked when the record which is currently used so that no one can able to update it at the same time.
Out of 5 user when the 1st user use the the data ,record updation is locked for other 4 user as soon as 1st user finishes his job other 4 users which is on queue the record is freed or unlocked for them so record locking is the main feature of on-line processing.
Now suppose the system is fail somehow now how we can know which transaction is successful and which are not here another concept is coming i.e Checkpointing which keep track of master file each and every time before and after updation.
Checkpointing helps user to restore its original position before updation or it can re-apply updation to an earlier copy.
Now if I want to track which transactions were actually applied or successful it can be done through a process named Logging which actually tracking the transactions.
· In On-Line processing each item having transaction code.
· In batch processing data is sorted but in on-line processing without sorting the transaction
data it is directly fed in the secondary storage device under CPU control
· All the data
is valid or not that is checked through validation process.
· All validate
data is stored on secondary storage device.
· All
validated data then processed through and updated immediately in master file.
ON-Line Enquiries
If the user having any enquiry and need immediate information then on-line systems are used.
Some special enquiry program is used in such systems where transactions need not to be upated only enquiry is needed.
Lets take an example if I want to enquire my PNR STATUS or Bank account balance no need to update the master file as because this is enquiry only.Each enquiry having some enquiry code if user makes any enquiry the system runs the respective program based on the enquiry code .The information will be shown on the display screen or the information also coming printed form.
Like in ATM if account holder want to know the balance then the output means balance coming on the ATM screen as well as we get balance in printed form.
Such systems use a special written programs called macros which is use to perform repetitive tasks .
It was used before but now we are using upgraded technique SQL(STRUCTURED QUERY LANGUAGE) which is more flexible than macros.
Remember On-line enquiry system does not do online transaction processing.
