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Itenerary-Segment-Flight dilemna, pls answer

 
Cengiz Kayay
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Hi List,

I know this question has been asked many times But I am really confused after all the readings.
Below is my understanding of the Itenerary-Segment-Flight relationship.
Are they correct???

- Customer searches for flights from London to NewYork.
- System searches all flights (FlightDAO) and returns a bunch of flight objects. Each flight object can have more than one leg. Eg: from London to Brussels and from Brussels to NewYork. (a connecting flight)
IF THAT IS THE CASE THEN, THE LEG IS NOT IN THE BDM ???
- Itenerary has segments and each segment has 1 flight.
- WHAT IS THE REAL PURPOSE OF THE SEGMENT HERE ?
- HOW WE WOULD ORGANIZE DIFFERENT FLIGHTS FOR A DESTINATION UNDER THE ITENERARY AND SEGMENTS.

I am really confused after all these readings. Can anybody please clarify?

Thanks for the answers..
 
Thomas Taeger
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Hi Cengiz,
try to find out synonyms, decide for one of the synonym names and replace all other aynonyms by your name. I even introduced quite new names first, but later I was able to come back to some of the given names.

Draw a good old data model first, with clear multiplicities(!) - use a class diagram for it and call it your corrected Business Domain Model later.

In this data model I would advise you strictly separating master data (segment prices ...) from the customer's activity data (his departure ... date / time, his seat no, ..., payment status, ...)

Originally posted by Cengiz Kayay:
- Customer searches for flights from London to NewYork.

Only one way, allways?

Originally posted by Cengiz Kayay:
... leg. Eg: from London to Brussels and from Brussels to NewYork. (a connecting flight)
IF THAT IS THE CASE THEN, THE LEG IS NOT IN THE BDM ???

Why not? But first decide, what a leg vs.(?) a segment vs.(?) a flight is.

Originally posted by Cengiz Kayay:
... and each segment has 1 flight.

What do you imagine what a segment is? What a flight is? Practically! Be aware the BDM could be wrong, many decided so.

Originally posted by Cengiz Kayay:
- WHAT IS THE REAL PURPOSE OF THE SEGMENT HERE ?

... to confuse you ... - see above, synonyms ... - but a good name, isn't it? And often used in the usecases ... - maybe your favorite ...

Originally posted by Cengiz Kayay:
- HOW WE WOULD ORGANIZE DIFFERENT FLIGHTS FOR A DESTINATION UNDER THE ITENERARY AND SEGMENTS.

Under segments?

GOTO line 1.

Sorry for the sarcasm, I exactly felt like you feel today.
But don't worry, the business analyst has allready been fired ...

Thomas
 
Cengiz Kayay
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Hi Tomas,

I feel certainly like now. But I will not give up.

My whole understanding was:

-Itenerary has segments (1 or many).
-Each segment has flights. (1 or many)

The relationship in the BDM confused me. In BDM it says 1 segment has 1 flight. How do you fit connecting flights (London->Brussels->NewYork) in a segment.Segment should stand for the trip from London to Newyork. And under a segment you should have connecting flights, etcs. Segment should be the structure to organize these connecting flights.

So either the BDM is wrong and I have to correct it OR
I have to find an other way to organize these connecting flights...
If the latter is the way to go, then what the hell is SEGMENT for?

From your answer I got the following conclusions:
When a customer ask a flight from London to NewYork, Flight table returns a bunch of flights. Each flight might have legs. (for connecting flights)
Then Segment is synonym for the Flight. and is used to price the whole flight etc.. The data model for this suggestion would be.

Itenerary - Fligts (1 to many)
Flight - Leg (0 to many)

Segment is a logical construct formed in the OO layer.


Please give this (man) a hand !

Thanks

Cengiz
 
Thomas Taeger
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Hello Cengiz,
think in smaller, national flights. Example:
Berlin -> Cologne -> Munich, all within Germany.

I only can guess the meanings of items as well. From start in Berlin up to touch down in Cologne for me would be one of the segments of the flight with the flight number MUC-007 from Berlin to Munich.

On boarding you will not look for a flight to Cologne but to the farmost destination, Munich, that is what the flight number is shown for.
But in my opinion the flight is pretty unimportant for us, because we must handle itineries being series of segments, maybe belonging to multiple flights, anyway.

Originally posted by Cengiz Kayay:
-Each segment has flights. (1 or many)

How can you say that before you have defined what a segment and a flight are for you?

I think everybody is allowed to define the meaning of these dark items as he thinks, there is no wrong or right, but you mus explicitely decide and define. Give each entity at least one or two typical attributes like departure town and time etc. to get a feeling for your entities.

Originally posted by Cengiz Kayay:
So either the BDM is wrong and I have to correct it ...

Yes.

Good luck
Thomas
 
Cengiz Kayay
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Hi Thomas,

Thanks for trying to explain it to me. I think about Segments as a logical grouping of flights. So each segment will have one flight. For a flight from London -> Germany -> NewYork has 2 segments and corresponding 2 flights. Segment will hold flight number -say- AB345 and the price.
Itenerary will hold segments of type departure or return.
Customer will pick up flights and the selection will be kept in segments.

I think this piece is the most gray area of this assignment.
I am not suprised that they fired that Business Analyst.

You have been a great help to me.
Regards
Cengiz
 
Venkat Kiran
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Hi,

I am new to this site and having a doubt with respect to scea assignment.
I am having a doubt with respect to main search screen where we will be displaying a list of cities From & To. Departure Date & Time.
I am planning to have a Separate Class for this which holds the City & Date Info along with FlightId. Does this make sense.

Regards
Venkat
 
Thomas Taeger
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Hi Cengiz,
Originally posted by Cengiz Kayay:
Segments as a logical grouping of flights.
... each segment will have one flight.


Isn't that contradictionary?
If you think as "Segments as a logical grouping of flights" than you have Segment-1----*-Flight.
If you think as "each segment will have one flight" than you have Segment-1----1-Flight or Segment-*----1-Flight.
That is really a difference. You still have to decide.

Originally posted by Cengiz Kayay:
Segment will hold flight number ...

Why isn't it called the segment number then?

I know that you are not allowed to discus the attribute level here, but it seems as you did not give your entities some typical attributes yet.
Do that first. Add multiplicities between the entities then.

Thomas
 
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