Ok. Now I do not (yet?) agree with Guarino, although I think what has
written about commitments is quite useful.
As far as I can see, Guarino mixes up the service and the service
contract. It is ok to talk about a service contract, but there is no
difference between such a contract and a contract that applies to other
(REA) resources like goods.
A company that wants to be sure that its supplier delivers certain items
upon calling can build a frame contract. In this frame contract the
supplier makes a commitmemnt. The company may have to pay for that, or
the reciprocal commitment that the supplier is the preferred supplier.
Or a consumer may order a house or boat to be built, and the constructor
may commit to that. (there could be a triggering moment involved, e.g. the
temperature being above zero).
In both cases, what is exchanged in the end is a good, not
service. So the definition of Guariano is too broad in that sense.
I could argue that it is also too narrow. If my wife cleans up my desk
without me having asked it, it is certainly a service, but there is no
explicit commitment. One could object that this is outside the economic
domain. In the economic domain, there will always be a commitment, even if
the commitment coincides with the action.
In our paper, we use REA and focus on services in the business domain. His
examples are from public services. He says: what do we pay for when we
fund such services by our taxes? I would say that we tax payers pay for
the capability to be present. This is of value to us citizens, even if we
never make use of it. The "goal" (our term) of this "service" is nothing
more or less than the availaibility of rescue services or care services to
be delivered. Not to be confused with the rescue service actually given to
a person (tax payer or not) in a fire. For that person, the availability
of the fire brigade is of no value, he wants to get out! That is the
"goal" of the rescue service.
A capability being present is not typical for services, a manufacturer
also has a manufacturing capability (contracted or not).
What is a bit untypical (but not exceptional) in the case of public
services like the ones mentioned is that someone is willing (really
willing ;-) to pay for the capability being present. In normal business,
nobody pays for that. But, as the example of frame contracts show, it
might be.
Of course, it is always a matter of terminology. We could call the hair
dressing a *service delivery* and the hair dresser having opened a shop a
*service availability*. But my feeling is that using the word service for
service delivery is most close to ordinary speech.
[although Merriam Webster also has these meanings of service:
- administrative division in government (so then it is the
service provider)
- the facility supplying some public demand, e.g. bus service. (cf. above)
- and more ..]
> Guarino also says that a service should not be defined only through
> the positive effects it has on resources. For example, defining a hair
> dress service only through the effects it has on someone's hair is not
> sufficient; we may also want to put constraints on the input resources
> used in the service, e.g. we only use schampoo with vegetarian
> ingredients. So, constraints should be included in service
> definitions.
> We have certainly included constraints in definitions of services in
> earlier papers, but in fact not in the CAiSE09 paper.
Guarino has a point in so far that we did not define yet a *service
description*. The goal will be an element, but we do not need to restrict
it to that.
However, I think a service does not differ here from goods, for which we
may have second-order value attributes or so.
It might be good to define service description, although I am not sure
there is a general criterion for what should be included in there. One may
say it is a set of constraints, but so are the ZF-axioms in set theory.
So my claim is that the notions of capability and service agreement and
service delivery are not necessary in the service ontology. They are
already in REA - or if they are not, they should be! - and are inherited
as long a services are viewed as resources.
What I am not sure about is whether the goal of a service could be a
"maintain" goal. Or, in other wordings, whether a distinction should be
made between goals to be reached once, or multiple times, or even
continuously. It depends on the time ontology underlying REA I guess,
whether all these cases can be seen as "state".
Ok, now you can start to shoot if you want!
Hans
I think that Guarino is too much focused on public emergency services.
They are one kind of services. His definition can be seen as the
description of the "goal" of these, and then indeed it is more than
availability. Typically it will be described in more detail, e.g. response
within 20 minutes.
Looking closer, the question is whether the "obligation" part is specific
(should be part of the goal description) or is something that the service
inherits from being a resource. The hair dresser also has an obligation to
cut my hair decentlty once he has entered the transaction; but this does
not mean that the goal of hairdressing is an obligation.
A difference between the two examples is that hairdressing refers to a
single event, and emergency service to something holding over a period of
time. But this is not an essential difference.
So I would like to stick to something like availability as the goal of the
emergency service, with the extra remark that once the administration has
entered a contract with the actor in question, indeed this actor
has an obligation to ensure this availability.
Availability can perhaps be worked out as something like "if event X
happens, then within time T, reaction R should be given"
I think this is a nice example where you pay for availability. Committed
to by the host when you pay (enter the contract). However, making the
analogy to Guarino's fire service, I would say that the triggering event
for use is when you start cooking - like when a citizen starts to use the
fire brigade service when she starts cooking (in another sense).
>
> This seems to work out,
> "buying a hair dress service" means "entering a contract where a hair
> dress service is to be provided when the customer asks for it"
> "buying emergency services" means "entering a contract where services
> are to be provided under very special circumstances"
> "buying goods" means "entering a contract where an ownership transfer
> service is to be provided thereby resulting in an ownership for the
> customer"
In my view, the second case is fundamentally different. Why? Ask yourself
the question whether the transaction succeeds when the customer would not
get his hair service, would not get snow services as it does not snow, or
would not get the book. Or alternatively, whether the customer has to pay
for it in these cases.
In the other two cases, there is not a succesful transaction, and the
customer will not pay.
However, in the case of the snow service, there is no reason why the
government would not pay. The snow service has fulfilled its part, and so
should the government.
[note: your first statement about hair service is ambiguous. I interpret
it in the normal way, that we are talking about a hair service. An
alternative interpretation is that the hair dresser only commits to
availabilty of his service, and the customer commits to nothing - since he
may choose himself to ask or not. I am not sure whether such a contract
occurs in real life, but your statement can be interpreted this way]
Now I recognize that when in the hair service/book service the transaction
fails because of lack of cooperation of the customer, this is usually
problematic (note that there is nothing problematic with a snow service
that does not go out as long as there is no snow). Depending on the
contract rules, the problem is solved in different ways. By default, the
customer does not need to pay for the service, but he may have to pay a
fine for contract breach. The contract may also stipulate that the
customer may have to pay anyway, as the transaction is deemed to be
realized at contract state. An example is a hotel reservation for which
you have to pay whether you show up or not (unless you cancel in time). In
the case of ownership transfer, the situation may be even more subtle. Is
the book not picked up yet by the customer his property or not? And when
he has paid for it but still not picked it up? This may become a legal
issue when the logistic company throws it away after one year, or when
ownership of the book implies certain responsibilities (for a book, this
is rather artificial, but for an animal, or a house this may be a real
issue). As far as I know, in general the problem is solved by balancing
the interests of both parties. So the hotel will charge the non-show 1
night, but not all nights.
These problematic situations are interesting as they reveal something
about what is going on in a transaction, but they should not be mixed up
with succesful transactions. A book being delivered and paid is a
succesful transaction. The same with hair service. If not deliverd, there
is not a succesful transaction, even if the provider is compensated.
In this respect, the public services of Guarino are fundamentally
different. If there is no snow, or no fire, then this does not mean that
the service is not delivered.
Of course, it may be that the service is not delivered. This would happen
when the government can prove that the service is not available. For
instance, on the basis of tests or periodic checks. In that case, the
government may decide to stop payment or take back money already given.
Hans
Related to the phases of an exchange process, here a short paper from a
few years ago that explicitly considers capacity checking and reservation,
and a pragmatic web paper that puts this in semantic web context.
There are more phasing models of course, like OASIS.
How to model it the best way in REA, I am not sure. My attempt: the snow
service isa service isa/typeof resource. The goal of the snow service is
making snow cleaning facilities available (cf cutting my hair short),
where snow cleaning facilities is another resource, or bunch of resources.
It would include the existence of these facilities (if not present
yet), the fact that they are ready-for-use as well as eager to
do so if needed. We could summarize this as "available".
The snow service is exchanged between some unit or private company and the
government in return of money, on the basis of a contract/SLA.
To complete the picture, one could model that these facilities are
resources used (consumed or used) in the snow cleaning as such, which is
also a service with the goal of making the street (resource) clean,
delivered to the public (no reciprocal value object - no
business transaction).
> Hans, we have only discussed your original bullet 3 (on service
> ontology). Feel free to start discussion on bullet 4 also!
>
In fact, I wanted to start today.
a short reaction on you health management and hair cut scenario. The kind
of failures that you describe is not the kind of things I was concerned
about for the caise10paper. See my post of Tuesday.
However, the relationship between business service and informational
service needs to be worked out better. Cf the remarks of Erik Proper at
the CAiSE09. The point is that if you have a BS X using an IS Y, then you
must be careful not to jump directly from X to Y when Y is offered by an
independent actor like an IT department. We should distinguish between
going from one level to another and from going from one actor (business)
to another (IT). When IT is an independent actor, it has its own business
concerns. And the Business department has its own informational concerns.
So what you typically get is that first you go from BS X to S X1, where
X1 is a supporting information service within the business, then as X1 is
about providing information, it can be supported by a service Y at the IT
department (or Birger's bike), but this Y itself also has a business level
(the contract between the IT dept and the business dept).
In this way, it is more complicated but you can account for
- that the information service provided is not equal to a business
service: there is a business service X1 with the responsibility of turning
the data provided by Y into something meaningful to the business
- that the IT dept has its own business goals - it also wants to be paid
for the service, to mention one thing.
I was thinking about adressing these problems in an extended version of
the CAiSE09 paper (item 2 of my agenda). I think that your (Birgers)
problems are more related to this rather than to the double-level
composition problem (item 4). Perhaps they can be related, but I don't see
yet.
you are completely right in the kind of concepts that we need to work
out these double or more levels. We don't need to restrict ourselves to
REA, but REA could be a good starting point. Here an excerpt from a paper
by Geerts and McCarthy www.msu.edu/~mccarth4/Alabama.doc
Commitments
At the end of the original REA paper, McCarthy called for extensions into
areas such as commitments (McCarthy, 1982, p.576), and the ontological
augmentations needed for this are displayed in Figure 4 where commitment
images for economic events are proposed. Ijiri (1975,p.130) defines a
commitment as an .agreement to execute an economic event in a well-defined
future that will result in either an increase of resources or a decrease
of resources.. Commitments are important economic phenomena, and we use
Ijiri.s term .executes. for the relation between them and the actual
economic events that follow them. We model the pair-wise connection of
requited commitments in a fashion similar to actual exchanges except we
substitute a reciprocal relationship between the two commitments where an
actual exchange has a duality relationship. Because of the importance of
reciprocal relationships, we take the additional step of reifying them at
a higher level of abstraction as economic agreements, and we differentiate
between two different types of agreements: contract and schedule, the
definition of which depends on the ultimate nature of the economic
exchange. A transfer executes a contract while a transformation executes
a schedule. For example, a sale executes a sales order which is part of a
contract, and a production job executes a production order which is part
of a schedule. Two additional relationships are needed to integrate the
commitments with the exchange description: reserves and partner. Reserves
is a special kind of stock-flow relationship that describes the scheduled
inflow and outflow of resources. A sales order results in a reservation of
the finished goods to be delivered, while a production order results in a
scheduled completion of finished goods. Finally, the partner relationship
is a special kind of participation relationship that describes the outside
agents participating in the commitments. We define the partner
relationship as a subtype of the outside relationship.
--
End of excerpt
So it seems that the concepts are already there. What is missing, as far
as I can see, is a language in which instantiated commitments can be
stated, although the OWL formalization of REA by Geert Poels may be
instrumental here.
I think this is good starting point.
But what is a challenging research question starting from here?
Hans
thanks for these interesting questions.
My take on it for the moment
- an economic exchange always involves a claim somehow (the other party
has to deliver, whatever it may be, or he can be brought to court)
- privileges are related to goods exchange, as far as the latter include
transfer of ownership, and ownership consists of a number of rights
(=privileges), although information exchange is a bit special.
In the case of lending (a book), there are also certain privileges
involved, but no ownership. A service offered by an entertainment park or
museum consists of the privilege of walking there (without the customer
being able to raise any other claim on the park "doing" something - only
this privilege is to be granted and effectuated, otherwise the park does
not deliver)
- a special kind of service *contains* a conditional obligation/claim or
privilege - like the insurance. The insurance company pays money (a good)
under certain conditions. In other related cases, the claim is not about a
good but about a service, e.g. a mobile car help service. The resource
offered when the condition holds needs to be distinguished from the
overall thing ("the insurance", "the firebrigade"). I agree that this
overall thing should be classified as a service, but for me it is still a
special type.
- about the value models: you are right that the value model as such does
not distinguish between these different phases/aspects. It can be
stretched a bit in this direction. The REA ontology might be a better
way of expressing the situation (but not graphically).
Yes, if you think of a good exchange that includes warranty service. One
could counter that the value object in this case is an aggregated
one. To which I could reply that that is true in virtually all cases,
still we classify the "thing" under its core function.
Two remarks
1. Where is the further specification of the service to be done? In the
process or in the contract? Hruby would put obligations and terms (=
conditional obligations) in the contract. This is an alternative to
consider.
2. If the specification or part of it is done by referring to the process,
then I think that our CAiSE attempt of expressing this by means of the
goal was not too bad. However, the constraint need to be expressed that
this goal (a REA event) is part of the process. This is what Maria's
diagram expresses, albeit in another way. Secondly, we may have to detail
the meaning of goal - or distinguishing two aspects. A clock mending
service, when consumed, is related to a conversion event of the watch
(broken-> happy). But at the same time, when produced, it is related to a
conversion (decrement) event of other resources (labour, ..). Since
production and consumption of the service are simultaneous, one might say
that both aspects are important. The service is the interface between the
two. A hotel room service consumes the room (some of its capacity) and
produces something that makes the guest happy (to put it in general
terms). If this makes sense, we could see the two aspects as two goals (we
did not say that a service must have 1 goal). Or we could say that a
service has both a goal (or goals) and a source/sources (capability?).
This was expressed in a figure in the CAiSE paper, but not formalized.