WWDC2001 Session 613

Transcript

Kind: captions
Language: en
my name is Alec no mayo I'm going to
talk to you about John COF I'm I'm Matt
we work in the field and the manager for
the I services team in France that's in
Europe that's you know on the other side
yet nothing and it's I actually have a
really hard session there because I'm
just between director web and you like
to Java client right so two technologies
where you don't write code you write
rules and so nice and I'm going to talk
to you about how to build an application
writing all the code you know I'm I'm a
developer so I code that's what I do for
a living so I'm going to talk you about
the code where do you put it what do you
put it what kind of code do you write
and how do you build a web objects
application I'm going to bring you from
the beginning to the end building a web
objects application start from somewhere
you know other thing and you go to the
end I'm going to try to do that in in a
logical way in a way you can build an
application it's not firm you can do
your application some of the ways you
can start from another point you can and
you can also eat it right you can do a
small part of your application this way
and then come back to the beginning and
we do another small part and cycle so
it's just to give you some pointers
whether where do you go to write a new F
application so where do you start well
most of the cases you start from your
data the application you want to
manipulate some data you want to you
already maybe have some that time the
database you want to access or you're
writing a complete new application and
and you want to create the complete
database put your data in it and control
everything so the first thing you have
to think about is what is the data
you're going to manipulate what is your
data model some people are like doing
you know nice graphics with plenty of
boxes all over the place and nice lines
between them
some of the people just
you know scrum but some stuff on a piece
of paper and some of the people just
stopped write code I'm mostly in the in
the last thing but that's that's a bad
thing you don't want to start like this
you probably want to stop by
understanding your that time and by
understanding where you're going so what
are the the pitch fool when you are
doing your data Modell what's what are
the problems we can have with you f when
you when you just even before using you
F when you out your data model you doing
your data model what other thing the
thing you need to think about first of
all your design when you do a design and
you put things in tables all over the
place
there is always performance application
if you explode everything and you have
tables everywhere well every time you're
going to do a stretch you're going to do
60 joints and your database is going to
be need to do all these joints all over
the place it's hot in some of the ways
for example here the blobs if you have
big chunk of data and this big chunk of
data are in the same tables and some of
the data every time you're going to
fetch a neo you're going to fetch this
blob well if this blob is a nice image
and 2 megabyte in size every time you
want to show a list of euros on the
screen you're going to fetch for every
one of those two megabytes data that you
actually don't really need so it's
actually easier to take this blob and to
move it in a separate table so you don't
have to to load it all the time just
load it when you need it
same thing with inheritance inheritance
is nice it's a nice way of thinking
about you know to partition my model and
I'm going to take this example that we
talked about that I heard about before
that but the person and the student and
the student and and the professor it's
nice you separate that nice in every
turn story and you create one table for
each and you do nice joints all over the
place
what if it's one layer deep probably
okay two layer deep we start getting you
know a little router if you go really
deep well it's a huge performance impact
and you're going
to search our applications going to
suffer for that so you probably want to
correlate some of these classes together
to to make some compromise in your
design in order to get some more
performances but you have to think about
this when you build your data model
trigger stored procedure we can deal
with it with UF so we some way to code
stored procedure there is some way to
deal with triggers but those things are
making you job others you're writing a
database from scratch if you're writing
your model from scratch don't put any of
these in there except eventually for
modification dates or creation dates you
can use triggers for these things but
otherwise try to avoid those if you have
some in your in your model you can deal
with them for triggers every time you
save something and use there is some
triggers you have to invalidate
everything that's around and we fetch
them from the database because the
debates change behind your back
stored procedures just a different kind
of invocation in working something to
get some data back so you have to write
some code to do an invocation of a
stored procedure and on the data model
at left button at least you have to
think about how your primary key are
generated primary here the the core
every time you create an object you're
going to need a primary key for it and
it's there is multiple ways to deal with
primary keys with the UF so when you
build another data model you have to see
what are the choices you have and which
one you're going to pick the first is
easy where it just lets you adapt to
undelete the JDBC gtb/c adapter knows
how to do it the result the different
plugins can do things differently but
basically the adapter know how to create
a primary key you might be primary key
in your model as any kind of integer
just going to work in web objects fives
are actually performance improvements in
this area because you're always getting
this thing in batches and not just one
by one so if you insert a thousand
objects or is not to size on one trip to
the database just uh I don't know me
you
primary key it's generating a unique
number from your process ID the bottom
number you're using and sort of the time
and some of the data is building this
huge of 24 by binary thing and and
that's it and you save a primary key in
the database
sometimes not if you need to present a
primary key to the user that's
definitely not a good choice after all
exactly similarity remember that if you
have an existing some existing data and
the primary key generation in there is
specific and doing some weird thing
taking actually current values that
exists in the object and concat and put
them together you can implement the
delegate database context new primary
key and I'll just return a dictionary
from there that will be a priority of
your object all the last the easy way is
if you want to do something simple is
you can mark the primary key an
attribute of your object and fills a new
set when the object is inserted in your
editing context say oh there is no
primary in there let's put something and
get to something from wherever you want
so you've built you use you've build you
data model or you thought about it you
know where all the data is going to be
you're going to design the data and now
you have to be modified you know this
magic in in in joy to web and your
actual Java client is all happening
because there is a model file and just
we there is wounds extracting stuff from
there so you need a modifier and the
modifier is actually not that easy to
get right so my first tip on your model
is spend time on your in your model just
don't try to rush it and just write on
your model and go write your application
just you know look at look at the yo-yo
model and click on all these inspectors
if there is checkbox you don't
understand in there well maybe you
should understand it and maybe you
should look in the documentation try to
find what this thing is doing or writing
a little test application trying to see
what this thing is doing one is changing
the other you can also compare your
relationships duration
you're building we ship some example
your model in in web objects in the
examples just compare the relationships
you have with relationships in the model
try to think how do they defeat the same
way in your design you'll is it the same
kind of relationship and look at the
relationship and see see in the
inspector if they look similar if
something is different try to think why
it's different
and finally just take this model and use
one of these great direct to something
technology and just drop your model in
there run the direct to Java client
application if the application looks
like something you can use your model is
probably okay if your application look
like is we are there with entities that
you don't expect there but then you know
it's in a separate window should be in
the same window maybe you do not express
the relationship exactly right the
heuristics in direct to Java client but
Carol yeah I really excel and giving you
a good overview of your of your data
model okay so I have a small application
that actually build most of it on in the
plane next web app or a book it's
fitting that on the tray so a builder is
a small project a small project and
inside this thing it's yet another bug
tracker system with a different database
so different know do different
everything not just everybody needs a
book tracker system and everybody wants
its own opening double-click on it
okay so that's a good start for demo
there we go
I have two times now that's probably
completely swept out okay so it's just a
really simple model file okay doing to
make it bigger you have a bug bug has
some component is is part of a component
there is some priority some state some
comments on this burg from some users a
user on the burger user on the command a
user on your components this kind of
this kind of relationship actually this
one is not the simplest one I can can
show there is something simpler so it's
a really simple model but I just want to
use this model to show you some some
little little things as you know you
know the data is usually little data
bitzleberger exist you have one you have
something like five different priority
in your model in your in your data and
you have maybe ten thousand words so
something you probably don't want if you
go look at priority yeah it's a Russian
ship to Berg should probably not be a
class properly should not probably not
be part of your of your of your priority
object because if it's part of a
priority object every time you you add a
new bug with this priority where we need
to add it to add this bug into the array
of all the bugs of this priority so
you're going to fetch all these objects
interests in order to install this thing
into it into this array so and it's it's
it's a costly fetch so this Russian ship
the inverse relationship is very
important especially from a black you
want to know what the priority is just
by following a pointer but the other way
you probably don't want it so the first
reason is performance you know you you
have this thing then you have this huge
array and you don't want to fetch it
the second reason is the priority you
probably want to fetch it at the
beginning when you launch the
application you want to fetch all the
priorities other states and this this
information that's you know standard for
all the bugs and you can modify and you
probably want to share this information
by everybody by every single leading in
context in your application every single
user in your application is going to use
the same objects
and in order to do that you use a share
leading context so share leading context
is a place where you can put objects and
every other editing context in the
application can use these objects
directly you only have one copy of these
objects in memory what that mean is your
object in your own editing context can
have a pointer to this priority you know
your bug has a pointer to this priority
but then you are in your share late in
context you have already shared object
and imagine that you have a pointer to
other bugs well all the bugs where all
the bugs in shared in contact and
editing context of this session or the
editing context of this session you
don't have the information so you cannot
put you cannot make a new you cannot
share an object that has a relationship
to data that's not shared so you need
you have one way point direction going
from your your objects into shared
object but from the shared object you
cannot go out to and to an object that's
not shared so that's that's why it's
this thing is not a class property
I see like to put the relationship in
the model though because it's actually
useful information that something you
can actually use when you're programming
that yo access level you can say I want
a Russian ship named bugs and grab it
from the model and do some stuff with it
you know qualify qualifying or fetch
something like this if you don't have a
Russian ship well you have to drill it
first and it's our it's nice to have it
in the model file let's go back to the
to the slide so what I'm going to say on
this model is very simple
so once you've built your model file you
have to think about your logic where are
you going to put to put your logic what
kind of what kind of code do you do you
write you know you have you have plenty
of coats right in your application and
some of them are more you know database
code suppose I'm more UI code some of
them up somewhere in the in the middle
so I'm going to show to review the
different class of code you have to
write in your application and where do
you put it and I'm going to start with
something I called yo logic so it's
basically everything that's on your
enterprise objects
the precede the first choice you make
with entreprise objects probably knowing
what is you entreprise object where did
you serve class you have you have
choices their first choice is you can
use a new generic wicker a new generic
record is just think think about it
think about it's just a dictionary
there's something you don't see some
values and it's just somewhere where you
put your data there is no code no logic
it's just your data so you just don't
quit code on this it's useful for some
little objects where you don't want to
put some logic on it for example my
priority object probably I don't want to
put code on it I can just make it an use
in your record and forget about it
you can subclass using your record if
you want to add logic to it or you can
use a custom enterprise object that
actually the superclass of yo generic
record to build more powerful
full-fledged object the choices of
suppressing using your record or custom
enterprise object it's just a matter of
taste actually in web objects 4 5 there
was a huge performance improvement if
you were so placing using a quick road
for long reasons but in web objects 5
you don't really care I can suppress one
of the other the only difference between
the two is using your clicker by default
isn't promoting a feature that's called
deferred floating and custom enterprise
object by default don't implement
deferred folding customer entreprise
objects are actually my favorite because
I like to control everything you know
I'm a freak and writing code but your
generic record just work and actually
the first thing you do when you create
an entrepreneurship is you go into your
module click the button and generate the
classes tab for the classes and you were
basically you write your accesses this
is standard access or for some things
i69 in your generic record you have
something written in the title and
something setting a title you see that
I'm so classing using every color I have
this weird code to
all value for key take stored value for
key I'll get into that in a minute
because this is this is the way the
framework is accessing your object and
you have to understand how the framework
says sex in your object to know we have
to put your code because if you don't
put your code at the right place the
framework is not going to invoke it the
way you want it
so accessors are really important you
have the access or to set the value on
the access or to get the value and you
can put code in there if somebody tells
you they cannot put you cannot put can
access so it's going to do a break or
lose that's not true you can't put code
in there but you have to be really
careful when you put code in there is
the story and why do you have to be
careful because key value coding is
actually relatively complex you have two
ways of accessing euros and the
frameworks we have are accessing the
eros in these two different ways if you
imagine you stack your view your
database at the bottom and the new
access and then you control and then the
interface and world object so when you
can move directly on thing yo-yo is
sitting in the middle
and the other one is changing your
object because the user want to what you
don't want is put some code in the to
add any coding when you're fetching the
objects probably not a good idea because
when you're fetching a bunch of objects
are with some performance it if you put
some codes there for every object you're
fetch or going to touch this code and
reproducing over and over so strawberry
you usually you don't put code in
there on the other side when you use key
when you're coding when when somebody is
involved in your objects yet t-value
coding and not stored key value coding
you may do something like let's take a
simple example you have modification
date in your object and when somebody
change the title of the bug it's
changing the modification date in every
in the when on the set title if you do
set title on yo it's going to say
creation modification that occurs now
and put that into you so changing the
title is actually changing two
attributes but when you fetch the object
from the database you don't want this
set title method to be called and change
your modification that you're not
modifying the object is just fetching it
so you have to understand how key value
coding works and how key value cutting
invoke those things in your object to
know where to put your code so the first
thing is T value cutting the user
interface is accessing your object what
is it calling in what order so the first
thing a value cutting tries to find is a
method with the name of your attribute
you know name actually one that's
missing on this slide everywhere
everywhere you see name you can replace
that by get name when Java so we
supposed to get version also so it's
looking for a method name get name or
name and then is looking for the
instance variable directly trying to
access it and see if I can put something
into this instance variable name name
that's a bad name for natural good to
explain wait
it's named named okay I use the next
thing and then key value coding still is
trying to find a method name underscore
name underscore get name
and or an attribute name underscore name
as opposed to this the set value are
doing the same thing looking for a
method name set name or the instance
variable name name or after that and
there is another in the way they're
doing thing and the big difference
between key value coding and store key
value killing is that the order is
different so we can show everything now
so imagine you have your of your object
and you have two meters on it when name
name and the other one name underscore
name if you are in TV decoding the one
is going to be called is name if you
want storable coding that's going to be
underscore name and you can play with
this thing you can turn them around
something in product in web objects five
is it's pure Java so all these methods
need to be public if you want key value
according to access your installs
variable directly you better make it
public if you are the top if your object
is not in the package will find it we
have ways to finding it but if you put
your object inside the package and you
make your yo-yo instance variable
protected web objects has no way to
access this thing when we were in
Objective C with the bridge and stuff we
are going from under you and just
putting the value from there but we
can't do that anymore we don't want to
add some stuff in the VM to do that you
know not clean so think about the the
the the protected and public and private
because it it's going to change the way
your object access these they are in a
package if they are not in a package
don't bother about it it's just going to
work like before exception box then
private so nobody can access in which
there are no package and protected not
in a package and protected we can still
access them you can change the way key
value cutting is walking by implementing
one of those method those are static
method but we do some magic so they are
inherited so if you can inherit this
classic method but so you can say I
don't want the frameworks to access to
says my field directly I just want the
framework to use the method never as a
field and should use toward exercise
which one no to this method there was no
difference between key value coding and
store TV recordings they all do exactly
the key value coding thing there is no
more study that you carry so you have
your access ORS in your object and this
the second thing usually put in your
object of dilation you know when when
the user change something in the in the
interface you want to make sure that the
thing is changing is correct so you
write validation method there is
multiple sort of validation method the
first one is just waiting an attribute
so in this case it's really bad but I
think that tribute named named way
whatever so you just write a method
variate name taking a string because my
name is a string and returning a string
and the thing is throwing an exception
and you just do whatever you want to
check on this particular attribute and
return the name if it's fine and for an
exception and an S validation variation
exception is there if there is any
problem with the name so here I don't
want the name of a component should
contain more than four characters just a
random rule that I made it this this
method are actually codes automatically
when you save your object there is
something that's running around and
checking all these things these are also
called if you use web objects when you
bang with web objects web objects is
actually calling these methods she use a
display group display group is also
calling these methods but when you save
it's called anyway so you have you sure
that this thing can go to the database
without being checked second kind of
validation method its variation methods
that take your world your object as a
world so when you delete an object you
here just doing something it's not very
interesting validation but I'm just
taking that and seen on the component
and my component could have served
components and I just want to make sure
that you care you cannot remove the part
you
to removal the child first so you cannot
suppress a component name if you have
something so this is very that
coordinate is actually the difference
not taking any any value is just
checking the euro object of the world
it's not returning anything if it
returned some sweet or nothing or throw
an exception so validation by a value
taking the value take the value return
the value and throw an exception that's
important because in in Java a method
signature is actually the name of the
method and the type of its arguments the
type of the return value is not part of
the signature so when we find a valid a
method we don't know what this thing is
returning so if you right away that
matter that's returning void we're not
going to notice and you're not returning
anything so we're going to put null in
your object because you returned void we
don't know what to find this thing we
put now and there is no really easy way
to get out of it to make sure that you
return something from a valid a
attribute method the three methods for
violating your object as a world very
late or delete variate winter by dead
for save I think they are
self-explanatory by default very dead
for insert invaded for save are doing
the same thing in the three method
although something missing on all these
methods they are they all throw they all
declare to throw an it's validation
exception validation exception this is
this three method something that's
important is to call super because if
you don't call super the valuation
that's that set in your modifier is not
going to happen because this isn't
validate for save that the framework is
actually going through all your
attributes and saying very that name
very they title validate something but
something else so you have to call
supers don't feel super all the
validations that you have set in value
that something is not going to be cold
and all the variation that's in your
modifier is not going to be cold either
so that's the control to avoid
of the method you can implement on your
logic unable to set null for key if you
have an attribute that's an integer we
cannot put null in there
so if we can put null we're going up
we're just throwing an exception
you should promote in able to set null
for key you can do we can stop there and
we're not going to throw if you
compliment is method a work from in
session
when you insert a new object in an to an
Indian context that's actually a place
when you create a new objects the first
thing you do even sorry when you insert
the subjects there may be some stuff you
want to put some default value in there
you want to set up a creation date this
is actually a method that's really
useful that you can use all the time a
way from fetch is once you fetch from
the database the framework is going to
call you and tell you a you've just been
restored from the database you can you
know set up some value in you and do
some method you should probably not
override are the two methods that are
used for the bye-bye UF that will change
and will read if you are if you're using
use in your quick world universities
those methods just so class and called
stock value for key and calling
automatically is to method if you're
implementing custom objects you see
these two methods before accessing an
accessor you call will read and before
setting of value you call will change
that that tell the editing context
looking at your object that something is
about to change or we need to fetch data
because it's going to need this data
these metals are called really really
really really often every time you
access an attribute every time you set
an attribute you call one or the two of
them so those are expensive method use
all over the place if you put cut in
there
and this code takes a little while to
run because you want to do some I don't
know something you're going to have
performance problem right there
because your fetch you can easily double
the time you're taking to fetch a set of
objects from the database by
implementing freely
of cutting there so that's why this is
this method you probably should not
overwrite them finally tip euros clean
when you're writing you're allergic you
you you can you know you can put your
access code in there war framework code
in there but if you if you don't keep
your object clean if you put specific
cut you access specific order war
framework specific codes that means that
you cannot use your logic anywhere else
and with all these Java client
technology maybe one day you will need
to have them on the client-side and if
you if you put whoa framework all in
there you will never be able to take
this thing and move it to the client
side I'll make one exception for you
access other utilities method that that
you can use to to do some specific
things you can use those because
actually those are apparently new access
but they are also in your distribution
in a different package so you can
actually use them in both places in but
you have to be careful by the way you
you use them if you use the same code in
both places you can obviously so you
have to so class and make the code using
two different packages but that's the
only exception that's okay
you can use that's the only place where
you can use you access specific code so
that's the first part of a view of your
code the code you're writing this is
your access or your vacation and your
business rules business rules are you
know just occurred that you need on your
EOS just going from one year to another
and doing you know I want to I want to
buy to buy a car of the car object I
have the the buyer and I do all this
saying that part of the business as part
of a thing you do so these are the
business for you can also implement in
there in the you logic you can assume
that everything is in the same editing
context
it's an important assertion because all
your objects are tied together they are
all in the same editing context with the
exceptions of shared in context that
should be completely transparent so
everything in the same any context me I
don't have to bother with an editing
context and I should think about this
one this other one you know you're all
in the same meeting context and the
first thing you do when you create one
of these object you put it in your
leading context so you know it's in
there and you don't have you don't have
to think about it this is not the place
where you where you create new leading
context where you move things from one
to the other
it's just everything isn't one anything
context and you you just write your
logic in there so that's the first
that's the first part of the code you're
writing the second part you probably
expect that most of you are familiar
with this this is your interface logic
you know the thing you used to connect
in web objects builder this is classic
thing you have an array of bug and you
have a Kronberg and you be the world
petitioner right and you have the little
comment here type in for saying that o
in this NS array there is there is some
bugs in there so this is just interface
logic that you used to connect in any
web objects builder when you build your
application
nothing really related to you F in there
and it's just you have some arrays of
object and you connect them you have the
inside of an object containing a boolean
value and you want to present a pop-up
with yes/no that's also something that
you do in your interface logic just
transfer just transformation of view of
your logic from one from one from one
type to another just for display purpose
so this go to the interface logic this
should not go into your yo-yo should you
know you know it's not because you have
a boolean in your you that your brain
should return yes or no as a strain it
should rehearse which won't return the
boolean not a string the string
translation from the boolean to the
string should be done in the UI so I
pass I'll do it rapidly for the
interface allergic
the interface logic you have everything
to connect in web builder you have all
your translation from boolean to strings
you also have in your interface allergic
everything that's related to cessation
classical session is the current user
who's connected to the application
that's a user you need when you invoke
your business logic on your EOS right
when you say when you have a user
connected to your database and the users
say ok I want to buy this piece of
hardware that you're setting in your
catalog you want to invoke the business
logic with this user I want to say this
user wants to guy this thing or this
this user shopping card I want to add
this in it so this is in the session and
this is part of your interface this part
of your application this is this is
replication keeping this state natural
you you just manipulating you and and
your application is getting all these
data there so what's what's missing in
there you know I have my interface logic
of my Year logic and I think it's it's
time to tell you a little story about
where do I put rice hopefully the
customer is not in the room and we not
say any names but I've been true to a
customer site about six months six
months ago and they had this nice
application with table sort of other
place in their world objects application
with HTML table all over the place and
every all the world components the world
page was one component 6,000 line of
code everything in there fetching
rearranging you know an array that the
swords were sorting everything within
there and this was a fairly complex page
with sorting all over the place you know
you click and you sort and Riyadh and of
course they call me because have some
ones on performance program and the
second thing is like everybody yes the
requirements change and they needed the
page in a different slightly different
way and
took them six weeks to do the page in a
slightly different way and of course
when we are done where they were
recording will change again and that's
approximately the time we have arrived
to the customer site and look at the
code and it was all monolithic out in
one page you don't want that you don't
want to put all your application
everything that you do everything you
fetch everything that you solve
everything all these things you don't
want to put that in your component right
because it's too much even if you the
people some people are so classing
components I'm making components and
subclassing the component and then so
classical component and then reusing
some patterns because that's already
better that's already way nicer because
you can actually reuse some of the code
that's like we some nice concept then I
told them that's not good place to put
these things and you know it just went
there for a day because I'm too
expensive in the condom you know me for
two days so I just went there for day
fix is fixed on bugs here and there and
tell them you know you think it's
completely monolithic you don't want to
put your code in your component put it
somewhere else came back to the customer
months after they moved all the code
they put everything inside the EOS as
this at that point I was you know you
can put code somewhere else it's not
because you have a component there and
yo there they can put something
something in the middle and then remind
me of this of these classes I had when I
was doing software engineering in school
and saying you know you have this great
thing coming from small talk it's called
model-view-controller
you know where this is exactly you have
the logic your logic that's what that's
your model right you have the interface
logic it's where you put your interface
that's yet your view right components
use of you and you need a place to put
your controller right so what I suggest
is that you think you think about this I
wrote a little application there
that I want to show you after but and
I'm going to make it available to you so
you can look at it and and I'm
interested by the feedback so where do
you put the rice you put that in a
controller layer but you can have
everything
so that's your application logic that's
where you you fetch you save you we
won't really cache on information
because you know that you're going to
need it at some other place this is the
place where you deal with all these
editing contacts you have also place
nested not listed and another thing you
can show you can support a back button
that's working nicely this is the place
where you do all your prefetching where
everything that's everything that you do
with us that's basically you'd want to
do that in your controller I don't want
to do that in your in your in your model
and you don't want to do that in your
interface I'm going to save my user
story for the end so what are the
advantages of having a controller that
yeah you know dependent on your
frameworks just to set of objects so
placing Java Longo objects and and not
touching anything in the frameworks just
accessing ufufu access and you have
metals and they are to build fresh
specification to refresh restrictions or
if the set of objects well you can reuse
them on the client side all this logic
that that potential is you know
component on some of the place if it's
just you know so class of an S or of any
subject and no NS object anymore Java
longer object there so class of object
you can use it you can move it to the
client side and you have to so class of
object so actually you can test it
without running your web objects
application you don't have to have a wou
component of a session or something you
can just write some three lines of code
and test the thing so what I want to
show you now the little if I can have
this screen on is this little
application I wrote where I was in on
the plane
so I have here an application that's
just a little simple application that's
another bug tracker system I'm going to
just to to run it I think I already
compiled it so should just run it's
coming
there we go
okay so it's just simple application
where you can you can look in and search
for bugs and and Oh run tests that's
actually something that's really
interesting is having all the tests
available from the you interface when
you're on development mode then you
click on the button and running on your
test so I'm going to to log in as power
user on this thing
that's highly really complex application
so it's a really simple application you
know you have you have users and what is
it isn't doing okay
you have user so you have the poor user
they have a green thing and you can you
know edit a user and you know just it's
just direct web but whiskered plenty of
line of code to do all this you can sort
of course reverse sort and all these
kind of things can go look at the
component that exists in my database so
you see that I'm submitting only bugs
for book tracker and I can create new
bugs so I wanted to do an application
that was not just a demo but some things
that actually work the this application
is fully functional except for the
search page because I do know that time
to finish it fell asleep in the plane so
everything else is functional that's why
I'm not clicking on the search button
because it's not the right thing but the
idea is you try to save an empty bug is
going to scream at you and telling you
that you know you have to write this you
write it you crazy so the validation
thing you're running and I'm showing the
right thing at the right place so how do
I do that it's actually here we go
so I split the application in four parts
so we have our logic or UI logic and we
have application logic and I also have
one test thing we are right where I put
all my tests actually I want to run the
test because it's fun like when you test
that's a good that's a good exercise
that's a customer site we actually have
the test
you launch the applications running of
the test and if one of the tests fail
you cannot launch the application stop
right there with the arrow and you
cannot go further so we need to fix the
test fix the the bird before you go
further and actually we don't have any
bug in the application so far because
every time you find a bug we make a new
test and you cannot launch your
application till you fix a bug so guess
what it's fixed in the day so this is
just a simple thing that's running all
my tests and if there was an arrow you
have a back trace there and you click on
this and you're going to you can see
what line it is in your in your file and
fix it right away
so the Euro logic you logic there is
nothing really in there it's just you
know going to take a component component
is simple in fact this we can see the
code in there so a component as a very
literal delete method that that check
that you cannot suppress a component if
you have sub component for it you cannot
suppress a component is Everest bugs
attached to this component the result of
sort of I'd name it oh that I was
looking for something so this is when I
put on the under them on the slide just
a simple validation method we also have
a really big nice business logic they
are asking the full name take the -
honey you can cat a you take everything
you go up the tree and you print the
name with slashes and the race is just
access so there is no really a lot of
business logic in there now I think that
in I'm going to advance in this
application because I think I'm going to
finish it now I'm going to add some
something to move to move to change the
states and things like that so I'm going
to add probably more business logic in
there state priority you know the state
is just it's not an illusion or quicker
but just could be no need for is the
only thing nice about the state is there
is access source we can just use them
and then there is two classes in there
that I put in my a logic because you
know you don't know where to put them
and they are actually really useful the
first one is
cheerleading context when you have you
know you have a set of objects and then
you fetch all your priorities in there
and then you add a new priority and you
want this thing to appear magically in
your share it in context so that's what
this subject is doing Elliott you look
at the code because it's a maybe a
little too long to explain here and I
have another little class here that I
use all over the place that's just bring
me a static method thing object count
with specification rectangle number so I
don't have to redo it all over the place
so that's basically my you nothing and
they are really really really simple my
user interface
I have isoda them here we go I have a
bunch of pages main page the component
list page the component editor page user
list user editor bug list buggy tutorial
when I have an editor I'm using it for
edit and also for new objects so it's
just you know all the UI and when you
look at one of these objects let's go
look at the user list in there it's just
you I glue there is really not a lot of
saying interesting things in there you
have the resubmitted can I delete an
object and right now returning true
because it's taking too much time to
check so I can actually remove the
method edit users just going to the next
page reading the user delete user is
just another page to just deleting the
user and and passing in another page and
new users just going as a page and
creating an user but if you look at this
code in there I'm never touching an user
never or amusing user of controllers see
edit user what I do is I create a page
the user editor and I create a new user
controller with the current user that's
that is the crunches that someone is in
my repetition so whatever I clicked and
I in the next page I tell it set to user
controller this is the controller I
incur do your job and all the logic is
in the user controller what is the user
controller well that's nice third
bucket that's in there so I have a
controller basically what is the
controller is something I don't like the
name if somebody a good suggestion for a
name and yes Model View controller but I
don't like the name controller so I mean
it may be a little difficult but a
controller is basically a shell on top
of an editing context is some things
that's keeping it in context eventually
creating a new editing context when you
build one that can that's calling this
hugely tease local instance of object my
use taking three kilometers long and I
made this smallest one and that's
locking and unlocking your editing
context and also asserting the locking
locking is something you have to be
aware of if you are writing a completely
threaded application if you are if you
only have one thread in the request
response loop in Webber objects you
don't really care about looking but it's
nice to see how it's done that's why I
put it in there so you can see how you
can lock and unlock your editing context
and having something that's running in
all the cases nicely so let's see what I
have as controller and I have a login
controller that's just doing you know
fetch with the fetch pacification to get
to get the current the user and
returning some error messages I have
some simple controller what is a simple
controller that's that's the controller
that's basically taking care of one
object when I was looking at the delete
user I was creating a controller with
the current user and telling it to
delete that's basically a controller for
this one object I can also create I can
I also have this controller that our
controller that are using a list of
things so and finally it's a demo so
first time you launch the application if
the thing is empty it's filling in the
feeling of the database with data fake
data and then I have all my tests I want
to insist on this because this is
actually something that saved a lot of
times
because you know you you if you don't
have the test if you it's a fact that
you have all these controllers and you
can test them by writing simple tests
I'm going to choose which to write show
you the login test in there you know
test against just creating you're
looking controller all set to use the
name set the password and ask it for the
user and if this thing blows up the user
doesn't it's not there so I'm just
asserting that this thing is working the
right here or also at the right time and
doing multiple things like this testing
multiple cases this is really nice
because imagine you have one of your
developer that way we have this huge
thing we need to add this feature and
it's just starting to act into the code
and write all these thing and commit it
into CVS and that's it that's finished
and then two weeks later you notice that
well it broke something well if you have
tests testing your controllers in all
the different ways if you break
something you're going to notice right
away and actually this happen more often
than you can think to is something
that's happening really really orphan so
I guess there is vomit I guess I'm there
I'm sure I just want to finish with we
can go back to the slide with my thing
actually I'm going to go blank just a
little story to tell you why I really
think this thing is good
add another customer site this one are
doing these things right because they
hired me to manage the project so this
case on site we started building an
application and we use this we use this
these concepts and all the way and I
told them you write test before you
write your code yeah test now so we add
test running we have everything running
is so nice and then the
the CEO of the of the company wanted to
see a to show a demo of this application
but he wanted to customize it because no
look who we are using whereas to look
for one of their customer and this is an
application that has a different look
they paid there they have people go into
the customer site and customizing these
applications to the different sites so
they look different
so in wanted the this application that's
we started from scratch something like
three months before you wanted the demo
to shoot one of these customer of course
we have anything ready this is just a
short demo we had something running but
it was with the logo of somebody yes so
you wanted it with logo of the person
and oh yeah and he wanted the current
application they have this field in
there that they don't have in there
well basically wanted a completely
different UI so we were well we cannot
do that and then we we went for it we
just you know we have to do it so let's
do this this UI so we went in there and
remove the UI and started from scratch
with the UI and basically we did demo
and we had to write something like six
lines of code because everything was
into controller and I didn't even think
myself that it was going to work that
well but actually everything is going to
controller so all you have to do is
actually wire stuff in web objects
builder and that's it and that's a
really really really powerful thing so I
don't have to I don't have all the
answers there is some stuff in this
application I'm not happy with there is
some some really glad I did it this way
some stuff I don't really like that's
why I didn't finish the search because
I'm not sure that the search I did is
great but even if it's a work in
progress I want you to look at it I want
really giving me feedback I don't
guarantee that I'm going to read all the
feedback okay probably going to read it
but I probably not going to answer
because I don't know many of you are in
this room but issues all send me 10
emails I won't be able to read you to
reply but I'm seeing tracing the
feedback I quick if you can go back to
this
to the screen for a minute I've used the
perfect some poor fool Apple technology
in there so if she goes on on page that
mac.com /uf there is this really nice
page as I did with PageMaker where you
can download this exact application that
just showed you and a feel free to send
me feedback feel free to send me any
comments that you have
I for trying to grade them if I can sign
me flames if you want I read them too
and okay back to the slides and that's
basically all I had to say today
as usual there is a lab downstairs 10:30
3:30 tomorrow go vote or webobjects
there is a direct to advanced director
to Java client just after this session
you can and some other session web
objects security I'm sure is going to
talk fast in there and the feedback
forum don't need the feedback from you
we want your feedback and we to contact
and I think this verb
you