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# Part 2 - Flight x Segment

Bruno Taranta Arruda
Greenhorn
Posts: 13
Hi ppl again,

I�ve been searching for topics but I didnt see any conclusion about this interpratation of segment and flight, the interpration I�m working on right now is that segment = flight based ond the BDM and the topics I�ve read, do you guys agree with this interpration ? Thanks a lot in advance.

Best Regards,

Tanveer Ahmad
Ranch Hand
Posts: 33
Hi Bruno,
You are right... A segment IS EQUAL TO a flight. But a flight IS NOT EQUAL TO a segment.
See, A Flight can go from A->B->C which is TWO segments A->B and B->C.

Thanks
Tanveer

Bruno Taranta Arruda
Greenhorn
Posts: 13
Hi,

Thanks for the answer, but now I�m confuded, what I understand about your explanation is that a flight is composed with some segments, but this is not what the BDM says, it has a relation 1->1 Flight-Segment. Can you please clarify ? thanks again

Best Regards,

Tanveer Ahmad
Ranch Hand
Posts: 33
Hi Bruno,
I did some google for Flight Segment:-
Segment of a flight involving a stopover, change of aircraft, or change of airline. Also called flight segment. "http://www.businessdictionary.com/definition/flight-leg.html"

That means there is a flight which goes from A->B->c->d. But you may want to go to X from A so your flight plan(Itinerary) will be - A->B->X. Here A->B is a segment and B->X is another. That way you have ONE segment by ONE flight and another FLIGHT for another SEGMENT. For an itinerary, segment = flight.

Thanks
Tanveer
[ February 06, 2008: Message edited by: Tanveer Ahmad ]

Srivastava Praveen
Greenhorn
Posts: 14
Hi

If airlines goes from A->B->C, then there are 2 flight and 2 segment, that is A->B and B->C. In this fashion both are same ?

I am planning to store booked seat information of customer in segment class. Please let me know whether I am correct ?

Tanveer Ahmad
Ranch Hand
Posts: 33
Hi Praveen,
I could not understand what do you mean when you say "They both are same.". Please put more light on this.

Thanks
Tanveer
[ February 10, 2008: Message edited by: Tanveer Ahmad ]

Alfred Jayaprakash
Greenhorn
Posts: 10
I always found Segment -> Flight, Flight -> Equipment as controversial requirements. While the bad news is that they have multiple interpretations, the good news is that all these interpretations are treated by SUN as correct, provided we choose a particular interpretation and stick to it throughout the assignment.
My interpretation was to choose Segment as a line-item in the Customer's itenary. In other words, Segment was defined as a trip to a destination that the customer wishes to travel. Meaning, if a customer wants to fly from NY to LA. NY-LA is treated as a segment. Note that NY-LA may have more than one Legs including either a Stopover(Intermediate flight stop, where the customer does not change the flight) or a Changeover(Intermediate flight stop, where the customer needs to get out of the flight to board another). Example, the flight from NY-LA may have a changeover flight at Atlanta. This still doesn't change my definition of Segment because LA is the destination that customer wishes to travel to and not Atlanta(See my definition above). So NY-LA is 1 segment which composes of 2 legs; NY-Atlanta and Atlanta-LA containing two different flights for each Legs(Since i mentioned it was a Changeover). My definition is consistent with Lufthansa Airlines (www.lufthansa.com)
Finally, as i mentioned earlier still there are multiple interpretations. It is up to you to choose one interpretation and stick it throughout the assignment. I suggest you to pick any Airlines website of your choice and run through how the whole thing works and how different terminologies are interpreted. Its a must before starting the assignment. Remember to ensure that your Assumptions, BDOM and Class Diagrams are consistent with your definitions and you are good to go .

Tanveer Ahmad
Ranch Hand
Posts: 33
Another question I have is :- Say there is a flight (Flight number X321) that takes off from A goes to B then C and D => A->B->C->D. Now my question is -

Will the flight number be same for all the legs (or segment or whatever) be the same??

Or will there be a change of flight number and a new flight number is given for each leg (or segment or whatever)?

Thanks
Tanveer

Marcus Jastrebowski
Ranch Hand
Posts: 55
Hi Tanveer,

Here's my thinking: I believe you should start your BDM analysis with the Itinerary, because the Customer first gets the Itinerary not the Flight. So in the example you just proposed above, the Customer's Itinerary would consist of 3 segments: A->B, B->C, C->D. Each one would be given an individual Flight number. These associations might seem rather strange to us and might not necessarily be the common business practice in any real-life airline reservation systems. But that is an assignment we've been given, and I do not think we should attempt to read between the lines or make any other unwarranted assumptions. (And I suggest you forget about a "leg" because that concept is undefined here.)

Cheers,
Marcus
[ February 11, 2008: Message edited by: Marcus Jastrebowski ]

Vhari
Greenhorn
Posts: 7
if each segment is assinged to particular flight then there must be one2one relation between them, is not it.. and each flight has 1 aircraft in summary the relations are

Customer2itineraries : ne2many (read it as one customer as multiple itnieraries)
itineraray2Segments = one2many
flight2segment= one2many (assuming the flight is origin to destination, each change over is one segment. Well the segment is a logical entity which holds data data of flight and seat info)
so the segment2seat = one2one ( a meaning full, with out a seat there is no segment at all)
flight2aircraft = one2many( logically valid)
remember flight and segmement are logical entity, where are seat, aircraft physical by nature...

Ben Souther
Sheriff
Posts: 13411
"HariS",
Please check your private messages.
-Ben

Rodrigo Lopes
Ranch Hand
Posts: 119
Make whatever interpretation you want, but state it clear in your assumptions list and, obviously, in your diagrams

Ben Souther
Sheriff
Posts: 13411
"Vhari",
Please check your private messages agin regarding an important administrative matter.
-Ben

Mark Quinn
Greenhorn
Posts: 21
My suggestion: if you can make it work using original BDM, do that. I got marked down on changing the relationship's multiplicity. I doubt that the Grader will carefully read your assumptions even if you make the correct assumptions for the relationships, such as many-to-many. There is no many-to-many in original BDM.

Abhinav Srivastava
Ranch Hand
Posts: 354
Does Flight<--->Segment 1:1 relationship mean only direct flights are offered?

Piotr Uryga
Ranch Hand
Posts: 68
Originally posted by Abhinav Srivastava:
Does Flight<--->Segment 1:1 relationship mean only direct flights are offered?

Isn't it easier to assume that each segment consist of one flight and one-way Itinerary can have many segments ?

I understand BDOM and UC analysis that way.

Opinions ?