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zheng shu

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since Jan 12, 2004
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Recent posts by zheng shu

order from or
then you get for free.
I applied on 14th of April, but have not received the voucher yet.
When did you apply?

Originally posted by bird cao:
what is server affinity

Server affinity refers to the capacity that a server in a cluster
is able to service requests from the same HTTP client during its
entire session. This is important if the process is stateful.
The load balancer usually adds its own Cookie to each request
it dispatchers to the server since it gets the first request
from the client. The cookie is pushed back to the client with
the first response. Thereafter, the client requests carry this
cookie (taht identifies the server that services the first response)
to the load balancer so that load balancer knows which server it
should dispatcher the follwing requests.
You buy a hardware load balancer and put it infront of your HTTP
Load-balancer, DMZ, firewall, or clustering, is not defined in
J2EE framework, so I guess it is not that important to know
everything in details. They are basically part of infrastructure.

Originally posted by Hu Yong Jun:
What is "place the cusomer on hold" meaning?
The frequent flyer mileage system has a web interface, so how does the travel agent application retrieve the customer's mileage? If the travel agent application retrieves mileage via xml-rpc, you have to modify the frequent flyer mileage system partly.
[ March 17, 2004: Message edited by: Hu Yong Jun ]

Talking about "requirement" here
"place the customer on hold" means that the agent has to hold
the customer on the phone (playing music to them and moves
to the shared computer to work with the FFM system, getting
the points redeemed. That is what it means. So you see, here
it is a manual process. You new system is supposed to automate
the process.
You can not change the protocol used by FFM because that is
the requirement that FFM remains unchanged. I can only tell
you (otherwise, it will be removed that FFM talks only HTTP
and that is what language your system has to talk in. How awkard
it is, that is the sole language it understands.
Allen/Bambara book is too long and costs you long time
to go through than needed. Cade's book is at least better
in size. The chapter on PartII is a bonus in Cade's book.
For part I test, both books are not as good as some free pages
you can find in the Internet. So for the sake of money and time,
buy the Cade's book.
Here is what I learnt and am following, in regard of sequence
diagram and class diagram:
1) create sequence diagram where you will identify both
object/class and messages (class method).
2) based on the sequence diagram, you define the class diagram.
repeat the above two steps in cycles until you get
The sequence diagram gives you an opprotunity to explore
the dynamic aspect of objects in the runtime. This dynamic
aspect is much more difficult to understand than the
static code that you want to produce. Through working
with sequence diagram first, you will gain clues what
methods you need to define and how data/message are exchanged
between instances.
If you have a complete sequence diagram, you get the
class diagram automatically by summerizing what you
have with sequnce diagram.
As for the component, component is a very abstract
concept that you can use to specify a chunck of packaged
code you want to use, at any levels, large or small.
This is I belive a concept more focusing on packaging,
i.e., a physical package, rather than logical one.
It makes more sense to use it at a large scale, rather
than a small one. I belive you can call a class
a component, but most time, the scale is too small to
make any real sense.

Originally posted by qing zhong:
Is there anybody thinking about "flight"? I have been confusing with it a few days. According to BDM in the assignment it's related with date, but I think it should be stable(just related with depature time). I think there should be another business model for the dynamic flight. But I don't know how to name it. Any suggestion?

Here what I came up with:
Flight should be indeed stable but they are related to dates and
cities. However, it is segment that is priced and sold to passages.
What I imaging is that segments are objects that passages buy.
There are a lot of segments that can be booksed through the system.
As you know, there are two versions of Core J2EE patterns.
Old one is still available from Sun's internet.
The new one (with application controller, context object)
is only available from their book. I am not very familiar with
the new one.
Can anybody tell me whether it is possible to pass the Part II
with only the old set of patterns? anyone has done so recently?
> For part II I read Core J2EE Patterns and looked up a few doubts I had > on UML syntax in the internet.
There are two versions of core j2ee patterns, one that is old and available
from Sun site. Another one is from their new book. Are you using
the old one or new one? My concern is that is it possible to pass part II with old one only?

Originally posted by patrick jiang:
"FBN does not wish to re-write this system at this time, but would like to have the content available to the customer using the web and the travel agent using an application. "

This only means that you should talk with it with HTTP (the only
protocol that CGI system understands), but this is not SOAP.
The most close thing is the XMLPRC.
sounds confusingly reasonable
This is only intented to discuss requirement, for your record
There has been a very useful post on java ranch on the business model:
I used to be able to come to this post from (Saloon discussion, topic
flight and segment), but it is gone now. Where I can
find it again?
My view on this is that the business model is not correct.
The Itinerary should contain (one to many) flights.
Each flight contains one equipment (airplane) and
multple segment (or called flight leg). For each of
the segment, the airplane takes off and lands down.
This enables us to model the scenario
that a passager might change airplane during the flight.
So the questions are:
1. is the model corrct?
2. if not, should we correct it as what I said above?
Being an engineer with a structuring mind, I just feel
unconfortable to work with the existing model that does not
seem to be right.
Thanks for you comments, and yes, no discussion on design.