Title: RE: [asap] Factory in ASAP
But
what is the charter if it is not the definition of the group? The purpose
of the charter is to define what is and is not suitable for discussion in this
forum. If we don't adher to the charter, then we risk losing focus, and
risk failing to produce anything at all. The people that
signed up for the group did so on a basis of what the charter
said.
It is
understandable that someone may have joined the group without understanding
completely the charter. To me, the essense
of what distinguishes an asynchronous service from other is the ability to
monitor and control it. It is not simply a normal service that takes a long
time. It is a service that might take long enough that you might change
your mind and cancel it. Without the ability to monitor and cancel, we are
not solving the problem defined by the charter. I am open to discussion on
this, but to me it is pretty clear.
Michael is not interested in this. He instead is interested in
services that are wireless friendly. This is an interesting and important
topic, but this is not the "Wireless Friendly Service Protocol" technical
comittee. I deeply regret discouraging his input, because he has provided
the best input so far in the group, and he clearly is knowledgeable in his
field. But in order to fair to everyone who has signed up for this group,
I feel I must try to keep the discussion focussed on the subject defined by the
charter.
If
someone wants to change the charter, then please take that discussion into a
subcommittee and off the main list. Then propose the new charter to the
group and put it to the vote. Until that time, I want to focus on the
problem defined by the current charter.
-Keith
-----Original Message-----
From: David RR Webber
[mailto:]
Sent: Friday, November 07, 2003 9:29
AM
To: Michael Shenfield; Keith Swenson; Mayilraj Krishnan; Jeffrey
Ricker
Cc: ASAP
Subject: Re: [asap] Factory in
ASAP
Keith,
Actually that's not at all so! The Charter
is NOT set in stone. You can change it - there is a process for doing
that - see the OASIS manual for that detail.
However - perhaps a better solution here is to
have a subcommittee. The subcommittee can go off and research "stuff"
and then come back and recommend something to the main TC.
So - for instance - you could have a SC to
investigate if the charter needs to be extended, if that would be appropriate
to do, and if it makes sense for the TC to do it as an extension of their
original focus.
To setup a TC you need to have a vote at your
next meeting - and then agree on what the terms of reference are for the SC,
then notify Jamie at OASIS - he sets up the SC area in Kavi - and then members
can signup there and participate, etc.
Hope this helps.
DW.
----- Original Message -----
From:
Michael
Shenfield
To: Keith Swenson ; Mayilraj
Krishnan ; Jeffrey Ricker
Cc: ASAP
Sent: Friday, November 07, 2003 11:49
AM
Subject: RE: [asap] Factory in
ASAP
Well...if what you say about the charter is correct and it's "carved
in stone" than all discussions about the scope are obsolete as it's
predefined. In this case I just retreat to observer status. I am not very
interested in "monitored and controlled" asynchronous services as they are
not wireless friendly by nature.
-----Original Message-----
From: Keith Swenson
[mailto:]
Sent: November 7, 2003 11:37
AM
To: Michael Shenfield; Keith Swenson; Mayilraj Krishnan;
Jeffrey Ricker
Cc: ASAP
Subject: RE: [asap] Factory in
ASAP
The charter of this technical committee specifically
states that the asynchronous service is something that that can be
monitored and controlled. This charter was put into place to guide
our discussion, and to keep us from getting off track. Since you
agree that a factory is needed to be able to monitor and control an
asynchronous service, then any discussion about alternate approaches
should be taken to a different technical committee.
Please understand, it is not that I don't respect your
position, or that I think the problem you are tyring to solve is
unimportant. It is only that this technical committee is set out to
solve is the problem defined by the charter. This technical
committee CAN NOT change the charter. In order to accomplish that
goal, we need to remain very much focussed on what the charter
says.
If you disagree with the charter, then make a new charter
and technical committee. It is not hard.
That being said, this technical committee MUST have a
protocol that allows for the monitoring and controlling of an asynchronous
service. There may be ways that involve somthing other than a
factory, and I am open to discussions about this.
It is possible that a particular IMPLEMENTATION of the
protocol "degrades" such that it instead of being monitorable and
controllable, it returns an error message instead. I am not saying
that all asynchronous services must be controllable or monitorable.
But, the protocol MUST provide for this capability.
The 80/20 rule works as long as you meet fundamental
criteria. For example, a car is not a car if it has no wheels.
The 20% that remains must include some sort wheels. The fundamental
criteria in this case is that a service can be monitored and
controlled.
-Keith
-----Original Message-----
From:
Michael Shenfield [mailto:]
Sent: Friday, November 07, 2003 7:13 AM
To: 'Keith Swenson'; Mayilraj Krishnan; Jeffrey Ricker
Cc: ASAP
Subject: RE: [asap]
Factory in ASAP
Re: "...Let me repeat my request from before:
Describe what must be done to
link
two systems at run time together such that one can
start a long term
process,
update it later, check its status, and terminate it if
necessary. It is
from
the dynamics of this linking that the advantages of this approach
appear..."
Sure, if you want to do all these things (update, check
status, terminate)
you'll need a factory.
Following 80-20 rule I would assume that only 20% of
async service implementations ever need these features,
therefore I am
quite convinced that it would be an
overkill to include it in the spec as a
requirement for ASAP compliance.
As we
represent two poles in the view on the scope of specification we
need
to let the rest of the group to express their
opinion, hopefully we will get
a features list
from Jeffrey anytime soon and be able to vote on specific
features to be included/excluded. Essentially it should solve an
argument
about the need for a factory.
Cheers,
Mike
-----Original Message-----
From:
Keith Swenson [mailto:]
Sent: November 7, 2003 9:50 AM
To: Michael Shenfield; Keith Swenson; Mayilraj Krishnan; Jeffrey
Ricker
Cc: ASAP
Subject:
RE: [asap] Factory in ASAP
>> Your other example is with 1,200,000,000
operations. Again I am puzzled.
>> Why not
to have just 4 operations Create, CheckStatus, Change, and Cancel
>> while passing an SSN as a parameter(part)?
Of course, in this case it would probably be
better to do what you suggest.
The example was
bad, but all I was using it for was to show that factories
can
be "virtual". A better
example might be that the factory address includes
the
name of a Java class which is a servlet
to be invokved. Or it even could
specify
the method on a particular class. The point
is that there does not need to
be any additional
overhead just because there are a number of "factories".
>> I think the mechanism of Web Service instantiation
>> should be left to framework providers.
Of course it should. Please don't confuse
the creation of a web service
with the creation of
an Asynchronous Service Instance. Creating an instance
of the service, is not really creating a new web
service. Just like
creating
and instance of an object is not creating any new methods.
>> We have prototype Web Services ... and
nowhere had to worry about
"factories"
As I mentioned, there are an unlimited number of
ways to do things. The
need for
factories comes only from wanting to link to
systems that expect factories.
You probably never
did this.
Let me repeat my request from
before: Describe what must be done to link
two systems at run time together such that one can start a long
term
process,
update it
later, check its status, and terminate it if necessary. It is
from
the dynamics of this linking
that the advantages of this approach appear.
(And
think back to the beginning of the OO days when all the programmers
were pointing out that any program can be written
without using OO
constructs.
The difference lies not in the program, but in the ability to reuse
it in
many different situations.)
-Keith Swenson
P.S. We have some
unfinished issue from an earlier conversion. I was
hoping that someone else would chime in, but since they have not I
will
follow with a separate message.
-----Original Message-----
From:
Michael Shenfield [mailto:]
Sent: Thursday, November 06, 2003 8:17 AM
To: 'Keith Swenson'; Mayilraj Krishnan; Jeffrey
Ricker
Cc: ASAP
Subject:
RE: [asap] Factory in ASAP
Wow...that's a long email. I had a hard time reading it on
my Blackberry at
breakfast :)
Now to the point. I don't think anybody argues the importance of
"Resource
Oriented" approach, that's why people
define multiple Web Services (and
ports) instead
of offering just one Web Service with a large number of
operations. Your analogy with object-oriented vs.
procedure-oriented?
True...the concepts are
related somehow. My question is what it all has to
do with the Factories? Your example on car repairs only shows that
one has
to define two web services
"CarRepairAppointment" and "AccessoryOrder". Your
other example is with 1,200,000,000 operations. Again I am
puzzled. Why not
to have just 4 operations Create,
CheckStatus, Change, and Cancel while
passing an
SSN as a parameter(part)? And again what it has to do with the
"Resource oriented" concept? Am I missing
something here?
Let me explain my position on
Factory. I don't have any problems with
somebody
implementing the Factory as a web service, I just don't see the
need for defining one in a standard. We have
prototype Web Services
implemented in .NET,
WebLogic, SunONE, and WebSphere and nowhere had to
worry about "factories" as Web Service access and instantiation is
taken
care by the framework.
I think the mechanism of Web Service instantiation
should be left to framework providers, it's non of the business of
Web
Service developer. The Web Service just have
to be there for you when
accessing the port. As
for ASAP specific information it can be easily passed
in the header (my "yes" vote) or as a predefined operation
(my "no" vote).
I've been programming COM and EJB
for years and was quite happy to see that
Web
Services got rid of programmer-aware "factory" concept, so I don't need
to call coInitialize(Ex), coCreateInstance(Ex),
etc. to get my COM interface
or to call EJBHome.create to get my EJBRemote. Why do we
need to go back in
time and define factory for
ASAP? Could you find "factory" as a principal
concept in any mainstream Web Services specification? I am not
aware of
any...
Cheers,
Mike
-----Original Message-----
From:
Keith Swenson [mailto:]
Sent: November 5, 2003 9:02 PM
To: Michael Shenfield; Mayilraj Krishnan; Jeffrey Ricker
Cc: ASAP
Subject: RE:
[asap] Factory in ASAP
The factory concept is the central concept to this whole
approach. Of
course, there are an infinite
variety of ways that one might approach a
particular problem. This particular approach uses a small
number of generic
"operations" on a large number of "resources". The
meaning of the operation
depends on the address of the resource. This is the
"Resource Oriented"
approach. The other
approach is an "Operation Oriented" approach.
One
should not be concerned about the multiplicity of the factories. The
existance of a factory does not mean that it takes
up resources on the host
machine. The
factory address can have data values encoded into it. I can,
if I wish, claim that I have 300 Million
factories, one for each person in
the USA, by
making the factory address have a SSN as a parameter (or any
other disambiguating value) in the address.
I don't have to make 300
million records ahead of
time. There is, then, no reason to try to reduce
the number of factories, nor is there any basis to equate a minimal
number
of factories to a minimal feature set.
The WWW functions on this principle of a few
operations on a large number of
addresses. For example, instead of using the web,
you could define an
operation to retrieve the
basic page, then an operation to retrieve each
graphic on the page, and another operation to retrieve the style
sheet for
the page, etc. Some people would
claim that this is a "good" way to design
the
system because getting the style sheet you use an operation
specifically
for getting the style sheet, and what you get back from
this operation is
always a style sheet.
Hence, it is strongly typed. Instead, the web merely
makes the page, the graphics, and the style sheet have
different addresses.
The same GET operation can be
used to get each one. Plus, I can remain
confident that if the future brings a new data type that can be
embedded in
a page, the same GET operation can
retrieve that data equally well. Some
people
will complain that to display a page you need to make a number of
GET
operations instead of one. True. Those same
people might argue that a
single XYZ operation
would be "simpler". This is NOT true, because the
specific information about the XYZ function must be specified some
way in
order to get the basic linking
accomplished. One problem, among many, is
that servers and browsers need to be upgraded simultaneously in
order to get
new capabilities. Simultaneous upgrade does not
happen in the real internet
world.
Back to ASAP: lets consider
a real example. A car dealer has two
asynchronous web services: one that people can use to make an
appointment at
the garage to get their car repaired, and the other to
order a particular
accessory for a car. The
reason I pick these examples is because they are
things that have a "duration" -- they persist over time.
There should be no
disagreement that for a customer to arrange for a repair
appointment some
data (expressed as XML) needs to
be sent from the customer to the car
dealer, and
that for ordering a accessory a different set of data needs to
be sent. This discussion then is really just
over how to talk about how
these two pieces of
data are different. Some approaches will make the
"operation name" be different between the two blocks of data.
The ASAP
approach makes the "address" be
different.
For this scenario, using an "Operation
Oriented" approach, we could define
operations for
CreateCarRepairAppointment, and CreateAccessoryOrder. We
would also need to define operations for
CheckCarRepairAppointmentStatus,
CancelCarRepairAppointment, ChangeCarRepairAppointment,
CheckAccessoryOrderStatus, CancelAccessoryOrder,
and ChangeAccessoryOrder.
The instance is
automagically created behind the scenes, the correlation is
encoded somewhere in the data passed.
Using the "Resource Oriented" approach, we say
there is an address for
"CarRepairAppointment" and
a different address for the "AccessoryOrder".
Specifically, these are the addresses of the factory. Knowing
these
addresses, we can call the generic
CreateInstance operation. We get an
instance
address which has the correlation information encoded into it. We
then can call the generic Cancel (actually
Terminate), Check (actually Get),
and Change (actually Set) on the instance.
As you can see there is a one to one mapping
between these two approaches.
The same number of
actual messages is passed, the same amount of data must
be stored.
The reason for taking the
"Resource Oriented" approach becomes more clear
when you carefully consider what must be done in order to link two
systems
together. There are systems that are
designed to be able to start remote
asynchronous
processes. They already know about the basic operations:
Create, Get, Set, and Terminate. In order to
link such a system to the
remote service, you must
give it the information to link. Using the
resource oriented approach, you only need to give it the address of
the
Factory resource. On the other hand,
using the "Operation Oriented"
approach, you must
first tell that system which operation is the create
operation. You have to program this somehow. You must
tell it which
operation is to be used to cancel
the remote service. Etc.
Once you buy
into the basic idea that actual operation is a combination of
an address and a generic operation, there are some
very cool things that can
be accomplished very easily: Imagine that company G
build (through any
means) a system that
automatically call the AccessoryOrder operations.
Company G is a trusted partner who brings a lot of business, so the
car
dealer implements a "Pre Approved Accessory
Order" that handles the order in
an expedited manner. Simply by changing the address
of the factory, all the
associated operations are changed congruently, and the
system interacts with
the expedited process.
For this
discussion, I used a NamingConvention: CreateXXX, CheckXXXStatus,
ChangeXXX, and CancelXXX. This might be an
alternative way to get the same
benefit. No
such naming convention exists. The naming convention approach
gets really nasty when you want to encode
something like a SSN into the
address. You
would have 1,200,000,000 operations. We can easily
communicate addresses of a factory, but communicating the names of
the
correct 4 operations from a field of 1.2
billion is somehow less
comfortable. Of
course you could hide this by having 300M virtual WSDL
files (generating on demand of course so it does not take any
space) but the
linking of operations is normally considered a design time
activity. Most
systems to call remote
processes are not really designed to take a WSDL file
at run time, search out the operation necessary according
to a naming
convention, and then call that
operation. It is messy if you want this kind
of flexibility. On the other hand, the "Resource
Oriented" approach is
designed for exactly this
kind of flexibility.
In summary, please think
carefully about the "DYNAMICS" of linking systems
at run time as is necessary in a real life internet environment
where change
is constant, and the systems you are linking to are not
under your control.
-Keith
-----Original Message-----
From: Michael
Shenfield [mailto:]
Sent: Wednesday, November 05, 2003 1:47 PM
To: Mayilraj Krishnan; Jeffrey Ricker
Cc: ASAP
Subject: RE:
[asap] Factory in ASAP
I already expressed my concerns about "Factory" concept.
In all existing Web
Services platforms that I am aware of the "Factory" is
invisible for the WS
developer and non of her/his
concern at the time of development and
deployment.
I think we should step back and define a minimal scope of ASAP
(as agreed at the last two conference calls). I
doubt "factory" should make
it there.
-----Original Message-----
From: Mayilraj Krishnan [mailto:]
Sent: November 5, 2003 3:32 PM
To: Jeffrey Ricker; ASAP
Subject: [asap]
Factory in ASAP
So far I have been thinking we need just only one factory
for ASAP
implementation or
the implementation of services could be conveniently placed under
one
logical ASAP factory.
I have two web services one is check inventory, shipping. Why do I
need to
create
two ASAP
factory? I think the ASAP pattern is generic enough, it can just
have one factory.
[In
terms of WSDL 1.2 we could map this to one ASAP (soap/transport
protocol) binding and one feature)]
Is that a right assumption?
Thanks
Mayilraj
At
11:35 AM 11/4/2003 -0500, Jeffrey Ricker wrote:
>I have attached files for describing the current draft of ASAP
in WSDL.
>These are rough draft documents that
have not been proofed.
>
>The asap.xsd describes the payloads
>The asap.wsdl is the basis for all ASAP services
>
>The concept here
is to treat ASAP as a binding. The message structures
>are all the same, the programmer only has to define the
ContextData and
>the ResultsData elements.
>
>The
checkInventory.wsdl and productLevel.xsd files provide an example of
>this ASAP-as-a-binding approach.
>
>Ricker
>
>
>
>
>To
unsubscribe from this mailing list (and be removed from the roster of
>the OASIS TC), go to
>http://www.oasis-open.org/apps/org/workgroup/asap/members/leave_workgroup.p
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