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Segment and Change Itinerary

 
Joe Law
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Hi,

I am using the following definition of segment:

A segment is an air journey which has exactly one takeoff and one landing. E.g., If you've a trip from A to C via B, you have 2 segments: A->B and B->C.

This definition seems to be quite common and reasonable to me.

However, if I apply this definition to the Change Itinerary use case, it will become very strange. I can only select a segment to change in the Change Itinerary use case. Let say if I have one trip from A to C and I will stop at X and Y, then I have 3 segments A->X, X->Y, Y->C. If I select the X->Y segment to change, I can only change to another trip like A->X->Z->Y->C. I can't change my trip to A->C or A->X->C or A->Y->C. Meaning that I can only make my trip more complicated but not simplied.

Any idea?

Joe
 
sioud abla
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Hi,
I think that if you have an Itenerary like A-->X, X-->Y, Y-->C and you decide to change the segment X-->Y, the Segment X->Y is deleted and another segment is created Z-->T for example, and the iteneray become A-->Z-->T-->C.
then you can not change the trip A-->C, but you can change A-->X-->C, A-->Y-->C.
SA.
 
Joseph Zhou
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My personal opinion, for a trip A->B->X->Y->C, if you delete X->Y(it may mean one or multiple segments one follow another from X tp Y), you will rebuild the X->Y use the same way as you "Prepare Itinerary". My question is: why we don't have "Change Itinerary" include "Prepare Itinerary" in assignment's use case diagram?
 
Joe Law
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Hi sioud abla,


I think that if you have an Itenerary like A-->X, X-->Y, Y-->C and you decide to change the segment X-->Y, the Segment X->Y is deleted and another segment is created Z-->T for example, and the iteneray become A-->Z-->T-->C.
then you can not change the trip A-->C, but you can change A-->X-->C, A-->Y-->C.


Acccording to your approach, you have not only changed the selected segment X->Y but you have also changed the original segments A->X and Y->C to A->Z and T->C respectively.

And even if this approach is used, there is still a lot of restriction on changing an itinerary...

Joe
 
Ramon Gill
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Hi Joe,
How about an Itinerary can only have 1 (one-way) or 2 (return) segments, with each segment consisting of 1 flight? Any other journey combination (A->B->C) would have to be set up as a series of iterations?

This would simplify the 'Change Itinerary'.

Ray
 
Joe Law
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Hi Ramon,


How about an Itinerary can only have 1 (one-way) or 2 (return) segments, with each segment consisting of 1 flight? Any other journey combination (A->B->C) would have to be set up as a series of iterations?

This would simplify the 'Change Itinerary'.


I've thought about this also. But in the post-condition of Price Itinerary and Pay Itinerary, it mentioned ".... for each segment of the flight". Your definition doesn't fit into this sentence?

Joe
 
Ramon Gill
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Hi Joe,
The post condition does tend to knock a hole in it. However, could an assumption be made that the post condition should have said 'itinerary' instead of 'segment'?

There are a number of contradictions in the use cases where assumptions need to be made. What about the 'Prepare' use case having pre-conditions that the customer must be 'logged in' and must have a 'profile', yet has alternative paths for these things ?

Ray
 
Anil Vupputuri
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Hi,

In worst case scenario, can make assumption of 'No Lay-overs' in
Source-->Destination, I know its a very rigid thing.

In that way we can also overcome pricing for internal segment change ie., pricing for X->Y in A->X->Y->C (assuming Source-A, Destination-C).

Otherwise how do you handle change of segment (X->Y) with pricing. As 'Price Itinerary' is included in 'Change Itinerary' use case and also its a 'flat price per destination'.
 
sioud abla
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--
Otherwise how do you handle change of segment (X->Y) with pricing. As 'Price Itinerary' is included in 'Change Itinerary' use case and also its a 'flat price per destination'.
--
because when you change a segment, you can change a seat and the price is per seat (first class or coach), in one equipment, one flight and one segment.
SA
 
Parag Doshi
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Guys..
not to complicate matters more..one thing, I think, is missing in this conversation, is the definition of 'leg' for a flight. For me, it simplified the pricing per segment and also supported the change itin/prepare itin use case by introducing the concept of 'leg of flight'.

Ofcourse, I have submitted my assig for grading and have not yet received a result..so consider it at ur own risk

Parag
 
Ajith Anand
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Originally posted by Joe Law:
Hi,

I am using the following definition of segment:

A segment is an air journey which has exactly one takeoff and one landing. E.g., If you've a trip from A to C via B, you have 2 segments: A->B and B->C.

This definition seems to be quite common and reasonable to me.

However, if I apply this definition to the Change Itinerary use case, it will become very strange. I can only select a segment to change in the Change Itinerary use case. Let say if I have one trip from A to C and I will stop at X and Y, then I have 3 segments A->X, X->Y, Y->C. If I select the X->Y segment to change, I can only change to another trip like A->X->Z->Y->C. I can't change my trip to A->C or A->X->C or A->Y->C. Meaning that I can only make my trip more complicated but not simplied.

Any idea?

Joe



Hi Joe,
I think your definition of the segment is definitely CORRECT.

You will need to take a few steps backwards ( to understand the Forest and Trees ) To solve the problem that you are facing with your interpretation of the usecase : "I can only select A segment to change".


Nowhere it says that users CANNOT iterate this usecase to mean "User Select SEGMENTS to change" applying this usecase iteratively if it needs.

Whether the change is applied to a single segment or a bunch of them, The user would anyways be changing it one by one...That is how I have interpreted "Select A SEGMENT to change"
 
Joe Law
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Hi Ajith,


Hi Joe,
I think your definition of the segment is definitely CORRECT.

You will need to take a few steps backwards ( to understand the Forest and Trees ) To solve the problem that you are facing with your interpretation of the usecase : "I can only select A segment to change".

Nowhere it says that users CANNOT iterate this usecase to mean "User Select SEGMENTS to change" applying this usecase iteratively if it needs.

Whether the change is applied to a single segment or a bunch of them, The user would anyways be changing it one by one...That is how I have interpreted "Select A SEGMENT to change"


The problem is most of the time when you change a segment, you will affect the adjcent segments. And this is not supported in Prepare Itinerary. E.g.,

If you have an itinerary A->X->Y->C and you want to change X->Y to E->F, then the A->X and Y->C segments will also be changed.

If you want to remove the X->Y segment, the itinerary will become A->X, Y->C and it is not valid anymore.

Therefore, you cannot change the segment one by one as suggested in your message.

Joe
 
Anil Vupputuri
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Originally posted by Parag Doshi:
Guys..
not to complicate matters more..one thing, I think, is missing in this conversation, is the definition of 'leg' for a flight. For me, it simplified the pricing per segment and also supported the change itin/prepare itin use case by introducing the concept of 'leg of flight'.

Ofcourse, I have submitted my assig for grading and have not yet received a result..so consider it at ur own risk

Parag

Hi Parag,

Are you saying something like,
Itinerary (1)-->Leg (1)-->Segment (1..*)-->Flight (1)-->Equipment (1)-->Seats (1..*)

assuming Leg is either Onward/Return journey, in this way 'Change Itin' can be easily handled by deleting existing Leg and create new
Leg using 'Prepare Itin'.

But about pricing, is it 'flat price per destination' or pricing per segment.
 
Ajith Anand
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Originally posted by Joe Law:
Hi Ajith,




If you have an itinerary A->X->Y->C and you want to change X->Y to E->F, then the A->X and Y->C segments will also be changed.


Joe

In this case, the user would be changing A->X, X->Y, Y->C . All of them . Not just the segment X->Y because if he chooses the second leg of his itinerary starting from a different station and ending up at a different station. it is common sense to change the initial and final segments too.

In real life , if I have a flight Zurich - Dubai, Dubai - Kuwait, Kuwait - Cairo. if I plan to change the segment Dubai - Kuwait to Amsterdam - Paris. If my idea is to reach Cairo. I definitely would make necessary changes to my Zurich - Dubai flight so as to make it for the connection flight from Amsterdam as well find out what connection I get from Paris to Cairo by making changes to Zurich - Dubai as well as Kuwait - Cairo segments. Lest I get stranded in one of these segments.

it is divide and conquer. Segment by Segment. IMHO it definitely works.
 
Ganesh Krishnan
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Hi Ajith,

I think whenever we make changes to any of the segments, the probability of other segments getting affected is almost certain. I think we can safely ASSUME that, on making changes to any of the segments, automatically all the other segments would be deleted. The reason for my assumption is anyhow prepare itineray is again going to happen.

Keep in mind that, in Prepare itineray the selection of flights is not Segment-wise but instead it is Itineray-wise....

what do you think on this???
 
Joe Law
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Hi Ganesh,

By changing one segment, you will at most change the 2 adjcent segments. Therefore, at most 3 segments are affected but not the whole departure/returning flight.

However, for the following 2 reasons, I am not very comfortable on this approach:

1) You need to do a lot more things or have a lot of extra alternative flow in Prepare Itinerary in order to support Change Itinerary.

2) In the specification of Change Itinerary and Price Itinerary, various places show that only one segment should be affected.

Anyway, I am now convinced that there is no definition of segment that has no conflict with the requirements. It is just a matter of more or less. And I believe that more than one definition can be used in this certification.

Joe
 
Josep Andreas
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Hi,
I do think the above definition of segment is not correct.

In the BDOM there is a one-to-one relation between flight and segment.
as segment is only important for pricing a flight between an origin
and a destination (=segment?).

if you plan a trip from A to B (via C,D and/or E) then only one segment is envolved.

Don't you agree?
 
It is sorta covered in the JavaRanch Style Guide.
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