Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: WORKFLOW MECHANISM FOR A STATELESS ENVIRONMENT
FIELD OF THE INVENTION
The present invention relates to a workflow solver,
and more particularly to a workflow mechanism for a stateless
or connectionless environment such as the Internet or an
Intranet.
BACKGROUND OF THE INVENTION
Business processes are typically analyzed in terms
of workflow items. These workflow items can be business
processes or documents. In the art, there are workflow
management systems to automate routing of the workflow items
based on specific business rules and roles employees play
during the process.
Known workflow management systems include Electronic
Procurement Services or EPS. An EPS provides government,
corporate and consumer markets with a simplified and
streamlined approach to traditional procurement processing.
An EPS typically utilizes client/server technology to buyers
and suppliers. Buyers can distribute the EPS client
application throughout their organization, thereby bringing
online purchasing directly to the desktops of purchasing
agents.
The purchasing agents, or other employees who have
been authorized to use the EPS, construct purchase orders by
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selecting from electronic catalogues. The EPS manages
procurement processing from this point forward, and
electronically routes the purchase orders through the approval
process to the appropriate suppliers for fulfilment. The
purchasing agents receive updates and confirmations from
suppliers up to the point of the shipment.
Electronic procurement systems have gained
acceptance, particularly in large governmental and corporate
organizations, because they automate and enhance the
procurement process without the need for extensive retraining
of the purchasing agents and support staff. By automating
labour-intensive tasks, such as purchase order requisition and
authorization, an electronic procurement system raises service
levels while at the same time reducing costs and clerical
errors.
Known electronic procurement systems are implemented
as a client-server application on a local area network or LAN.
A well-known EPS is World Purchasing ProfessionalTM or WPP from
the IBM Corporation. The WPP system comprises a client-server
application that gives the purchasing department in
corporations or government the ability to link electronically
to both internal departments and external agencies and
suppliers.
The architecture of a conventional workflow
management system 1 according to the prior art is shown in
Fig. 1. The workflow management system 1 comprises a workflow
server 2 and a plurality of workflow clients 3, shown
individually as 3a, 3b,..., 3n. The workflow server 2 and
clients 3 are connected via a local area network (LAN) 4, or
a wide area network (WAN). Each workflow item 3 comprises two
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principal components: a data element denoted by W data, and
a business rules or semantics element denoted by W semantics.
The server 2 includes a workflow engine 5 which processes the
workflow data (W data) according to the semantics (W
semantics) for the workflow item. In a traditional workflow
management system 1 as shown in Fig. 1, the workflow server 2
functions as a central server which contains all the business
rules (i.e. W semantics) for the system 1, and the workflow
clients 3 are continuously connected to the server 2 through
the LAN 4 as indicated by the solid lines. Because the
clients 3 are continuously connected to the server 2, the
workflow engine 5 needs to maintain the context of each client
3. Such demands typically result in a complex workflow engine
5.
In recent years the Internet has emerged as the
dominant communications network, and provides enormous
potential for electronic commerce. The Internet comprises a
system of linked computer networks, e.g. LAN's and WAN's,
which is worldwide in scope, and provides data communications
over the seamless collection of networks. As such, the
Internet is not a computer network, as is commonly thought,
but rather a stateless environment which provides a mechanism
for connecting existing computer networks.
In a stateless or connectionless environment such as
the Internet, connections among the computers are not long
term. These connections are made only for a short time in
order to transfer data. Once data is transferred, connection
between the computers is broken and computers are free to work
on the data as they wish. Once the work is done, the
computers establish connection again. Because a continuous
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connection during the whole business process is not
maintained, it is very difficult to maintain the context for
a process. In a conventional networked environment as shown
in Fig. 1, the permanence of the connections between the
server 2 and the client machines 3 allow the server 2 to
continuously maintain the context of the business process.
The principle problem that arises for a workflow
management system in a connectionless network, such as the
Internet, is the support for automatic routing and n-level of
approvals in the connectionless network. This problem arises
because the context of the business process is not maintained
in a connectionless network. There is no single source, i.e.
a server, where all the semantics of the workflow items can be
kept. Connections between clients and servers are
continuously made and broken and as a result context
information is lost. By definition, a workflow server must
have access to all workflow items in order to manage the
workflow.
In a traditional workflow system, rules to control
the business logic are kept in the workflow server 2 (Fig. 1)
and context information about the workflow item is always
maintained by the server. In a connectionless environment
this information needs to be maintained by the workflow items.
Another shortcoming with existing workflow
management systems is the limitations with respect to
granularity. In a practical system, this means analyzing the
business workflow either in terms of processes or documents.
It will however be appreciated that real world business
comprise a union of processes and documents.
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Accordingly, there is a need for a document
management system or workflow system for stateless environment
such as the Internet or an Intranet. Preferably, such a
system provides a compact design which is configurable for
different applications and supports nth-granularity (where
document state is determined by line-level approval as well as
other business criteria).
BRIEF SUMMARY OF THE INVENTION
The present invention provides a workflow mechanism
for a connectionless or stateless environment such as the
Internet or an Intranet. According to the invention, the
mechanism includes means for maintaining the business logic
and context information about the workflow in the workflow
item itself.
The mechanism comprises a workflow architecture
which includes a data component for the workflow item or
object, a semantics component and an inference engine
component. According to the invention, all three components
are packaged in the workflow item or object.
It is a feature of the workflow mechanism that
workflow objects are attached to the documents and transported
with the document. This allows the document (or process) to
be manipulated by a client without requiring the client to
remain connected with any server. Accordingly, the workflow
mechanism eliminates the need for the workflow server as in
conventional workflow management systems.
The present invention also provides an inference
engine for solving workflow in a connectionless environment.
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The inference engine includes means for maintaining the
context of the workflow items in the workflow management
system and means for implementing the arbitrary business rules
and organizational structure as first order constraints for
the engine. The engine includes a Justification-based Truth
Maintenance System. The engine according to the present
invention results in a compact design which makes it suitable
for integration with workflow items.
It is a feature of the engine that Justifications
can be introduced as needed, and in most cases the
Justifications can be introduced at runtime. Justifications
are encoded as propositional logic expressions which serve as
constraints for the inference engine. Accordingly, arbitrary
business rules which affect workflow can be added. As such a
workflow system utilizing a mechanism according to the present
invention can be used to manage both processes and documents,
and provides nth-degree granularity.
The present invention provides a workflow mechanism
for a stateless environment such as the Internet or an
Intranet. The workflow mechanism includes the following
features: (a) support for complete workflow for a document or
set of documents for complex business rules; (b) support for
n-level of approvals and user configurable; (c) support for
authority delegations and re-routing of the document; (d)
support multiple users with multiple roles and multiple
privileges on multiple documents; and (e) support for
arbitrary business logic. The workflow mechanism also
includes the capability to maintain and control line level as
well as document level approval states for n-level of
approvers.
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In a first aspect, the present invention provides a
mechanism for processing a workflow item in a stateless
environment such as the Internet, the mechanism comprising: a
data module for data elements associated with the workflow
item; a semantics module for rules associated with the
workflow item; an engine for applying the rules to the data
elements; wherein the data module, the semantics module and
the engine are contained in the workflow item and transported
with the workflow item when the workflow item is moved in the
stateless environment.
In a second aspect, the present invention provides
a method for processing a workflow item in a stateless
environment comprising client machines and servers, the method
comprising the steps of: storing data elements associated with
the workflow item in a data module; storing rules associated
with the workflow item in a semantics module; loading the data
module and the semantics module with the workflow item;
loading an engine in the workflow item together with the data
module and the semantics module; routing the workflow item
together with the loaded data and semantics modules and the
engine to one or more of the client machines in the stateless
environment; utilizing the engine to apply rules from the
semantics module to data elements in the data module to
process the workflow item on the associated client machine
independently of the server.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will now be made to the accompanying
drawings, which show a preferred embodiment of the present
invention, by way of example, and in which:
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Fig. 1 shows a conventional workflow management
system according to the prior art;
Fig. 2 shows in block diagram a workflow management
system according to the present invention;
Fig. 3 shows in a workflow mechanism for the
workflow management system of Fig. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides a workflow mechanism
for workflow management systems. In the following
description, the details of the workflow mechanism are
described in the context of a workflow management system.
However, other components of the workflow management system
which do not form part of the invention, such as the
mechanisms for workflow item delivery, tracking, monitoring,
security, are not part of this disclosure.
Reference is made to Fig. 2, which shows a workflow
management system indicated generally by 100. The workflow
management system 100 is intended for operation in a
connectionless or stateless environment such as the Internet
or an Intranet. The workflow management system 100 comprises
one or more servers 101 and a series of clients 102 and
workflow items or objects 103. In Fig. 2, the servers are
shown individually as lOla, 101b,...... , 102m, and the clients
are shown individually as 102a, 102b,...... , 102n. The clients
102 comprise computers or workstations which are situated, in
a corporate application for example, in head office, branch
office, or remote computers with dial-in access. The dotted
connections depicted in Fig. 2 represent transient
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connections, and therefore, in a connectionless network, the
role of client and server may not be so clearly defined.
The workflow items 103 are shown individually as
103a, 103b, 103c,..., 103n in Fig. 2. According to the
invention, the workflow item 103 comprises three components:
a data component W data, a semantics or business rules
component W semantics, and an inference engine component W
engine. In Fig. 2, the data component is denoted by 104, the
semantics component by 105 and the inference engine by 106.
According to this aspect of the invention, when a workflow
item 103 is downloaded to a client, the data component W data
(104 in Fig. 2) and the rules component W semantics (105 in
Fig. 2) are downloaded together with the workflow engine W
engine ( 106 in Fig. 2). The workflow engine 106 is the
component which works on the data 104 (W data) in accordance
with the business rules contained in the semantics component
105 (W semantics). In order to provide the capability for
downloading, the workflow engine 106 features a lightweight
and compact design, while at the same time having the
processing power to work on the business rule logic defined by
the rules component W semantics or 105.
The workflow engine 106 according to this aspect of
the invention is shown in more detail in Fig. 3. The workflow
engine 106 comprises an inference engine 111 and a truth
maintenance system (TMS) 112. The truth maintenance system
112 comprises a constraint network which utilizes
justifications. In the context of the present invention,
justifications comprise simple first order propositional
clauses. Advantageously, a constraint network composed of
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justifications comprising simple propositional clauses is
extremely fast to evaluate. It has been found that the
current state of the document (or a business process) can be
inferred by the justifications currently believed. As
depicted in Fig. 3, the truth maintenance system 112 records
justifications (link 113), and the inference engine 111 draws
inferences from the justifications recorded in the TMS 112
(link 114).
Referring to Fig. 3, the inference engine 111
communicates the constraints on a document to the truth
maintenance system 112 in the form of justifications, i.e.
propositional clauses (link 113). A justification comprises
three parts:
(1) Consequent in the fact in the inference engine
which is inferred.
(2) Antecedents are the facts which are used for the
inference rule.
(3) Informant is supplied by the inference engine to
explain the inference in more detail.
In the context of the present invention, each justification is
interpreted as a simple propositional definite clause or Horn
clause comprising antecedents An and consequences Cm. For
example, a clause Al,A2,A3...An => Cm means that if the
antecedents, Al,A2,A3...An, are believed in the current
context, then that implies consequent Cm. It has been found
that most of the constraints or justifications needed to
control the workflow in an electronic procurement system (EPS)
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can be formulated within the propositional calculas for the
truth management system 112. Antecedents (An) and
consequences (Cm) are represented within the constraint
network in the truth maintenance system 112 in the form of
"nodes". The most common query posed by the inference engine
111 to the truth maintenance system 112 is whether a node
(i.e. consequence Cm) logically follows from the current
database state (i.e. the antecedents An stored in the W data
component 104) for the document or process.
As such, the specification of the truth maintenance
system 112 is defined by two sets of data which are stored in
the W data component 105 of the workflow item 103. The two
sets of data comprise: (1) a set of antecedents (i.e. A1,
A2,...An), and (2) a set of consequences (i.e. C1, C2,...Cm).
These two sets of data will evolve as the various workflow
processes evolve. As a result, the truth maintenance system
112 can correctly answer queries on the contents of these two
sets at the moment the query is made. A flln~mental task of
the truth maintenance system 112 is to answer queries about
what the nodes are holding (i.e. what is believed in) given
the current set of enabled justifications. The general
implementation aspects of a truth maintenance system in
accordance with the present invention are within the
understanding of one skilled in the art and are further
described in Building Problem Solvers by Kenneth D. Forbus and
Johan de Kleer available from The MIT Press, Cambridge,
Massachusetts.
According to another aspect, automatic routing of
workflow items 103 is provided by encoding routing information
as justifications, i.e. sets of propositional constraints,
which are also stored in the W data component 104 of the
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workflow item 103. The propositional constraints provide
routing information and the engine 106 uses the routing
information to route the workflow item 103 without any further
communication with a workflow server 101 (Fig. 2).
5As the workflow mechanism is designed to work in a
connectionless environment, such as the Internet, changes in
the organization structure and business rules are not
reflected immediately until the workflow item is downloaded
again. However this can be solved by implementing a
notification scheme when business rules change or the
organization structure changes. For example, the clients 102
may access a server lOlb (e.g. Website) to download the
update, or the clients 102 may be automatically notified by
the server lOlb, e.g. using e-mail.
15The operation of the workflow mechanism, i.e. the
workflow engine 106 is now described in the context of an
electronic procurement system, such as the World Purchasing
ProfessionalTM (WPP) system from the IBM Corporation. Briefly,
the WPP system first records "justifications" in the truth
20maintenance system 112. As the document progresses, the WPP
enables or retracts antecedents (i.e. An) in the truth
maintenance system 112. The WPP (i.e. work management system)
queries the truth maintenance system 112 about the current
state of the document. The truth maintenance system 112
utilizes the recorded justifications (i.e. propositional
constraints) in the constraint network to provide the current
state of the document.
For the workflow engine 106, the state of a document
is a consequence of various antecedents (An) which are
currently believed in. For example, the antecedents (An) for
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a document may be represented and partitioned into the
following sets:
(1) Role of the current user;
(2) Privileges of the user;
(3) Action of the user;
(4) Type of the document being worked on;
(5) Original state of the document;
(6) Resultant states of components (i.e. Line level
states, etc.);
(7) Result of Business Rule 1;
(8) Result of Business Rule 2, etc...
As the processing of the document continues, the WPP will
choose or enable one antecedent from each of the above sets of
antecedents. The truth maintenance system 112 utilizes the
justifications already recorded to answer which consequences
are now believed in and the inference engine 111 determines
the new state that the document can have. This feature is
further described by considering the processing of a "Purchase
Requisition (PR)" document. The Purchase Requisition document
has the following sets of antecedents:
(1) Role of current user (i.e. Initiating Officer,
Supporting Officer, Approving Officer);
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(2) Privileges of the user (i.e. Can browse, Can
approve, Can modify);
(3) Action of the User (i.e. Modifying, Approving,
Browsing);
(4) Type of the document (i.e. PR (Purchase
Requisition), PO (Purchase Order), ITT (Invitation
To Tender), ITQ (Invitation To Quote))
(5) Original state of the document (i.e. Work in
Progress, Approved, Rejected, Ready for Approval,
etc... );
(6) Resultant states of components (i.e. All Line Items
Approved, Some Are Rejected, Some Are Being
Investigated, All Are Rejected, No Action Taken,
etc...);
(7) Business Rule 1 (i.e. PR Value < 30,000, PR Value
More Than 30,000).
For this example, the following justifications (i.e.
propositional clauses) are encoded in the truth maintenance
system 112:
(1) Setl(InitiatingOfficer) & Set2(canApprove) &
Set3(Approving) & Set4(PR) & set 5(WorkInProgress)
& set 6(NotApplicable) & set 5(NotApplicable) = = =
= > Work in Progress by Initiating Officer.
(2) Setl(Approving Officer) & Set2(canApprove) & Set
3(Approving) & Set4(PR) & Set5(ReadyForApproval) &
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Set6(AllLineItemsApproved) & Set7(Value < 30,000) =
= = = = > PR ready for PO process.
(3) Setl(ApprovingOfficer) & Set2(canApprove) &
Set3(Approving) & Set4(PR) & Set5(ReadyForApprovel)
& Set6(AllLineItemsApproved) & Set7(Value > 30,000)
= = = = = > PR ready for Tender process.
During the processing of the document (i.e. workflow item
103), the WPP enables antecedents (for example, "Initiating
Officer can Approve") from each set, and the truth maintenance
system 112 provides the WPP with the state of the document
depending upon which justification is true and therefore the
associated consequence is to be believed in.
The workflow engine 106 according to the present
invention takes advantage of the fact that most of the
justifications can be created beforehand, i.e. during the
business process analysis stage. The truth maintenance system
112 appropriately stores these justifications (i.e.
antecedents and consequences) in a relational database or in
the form of persistent objects which are being used for the
application. As work continues, the WPP merely enables or
disables justifications, and the truth maintenance system 112
provides the resultant state of the document(s) (i.e. workflow
item) by solving the enabled justifications.
The workflow engine 106 according to the present
invention provides the capability to dynamically add new
justifications. The new justifications are recorded in the
truth maintenance system 112 by the WPP. Accordingly, the
workflow management process can be refined by introducing or
retracting justifications at any time, without the need for
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further coding. New justifications can be entered by
providing a user interface in the WPP where the user drags and
drops various antecedents from the sets of antecedents which
define a process. The particular implementation of such a
user interface is within the understanding of one skilled in
the art.
In summary, the workflow mechanism according to the
present invention includes a truth maintenance system 112 in
which rule(s) can be attached to each node in the constraint
network, so that if a node is believed in, it can trigger
those rules which perform a business task. It will be
appreciated that the resulting code for the inference engine
111 and the truth maintenance system 112 can be very compact.
This means the inference engine 111 and truth maintenance
system 112 can be downloaded as part of the applets in order
to track the states of the document which is downloaded to be
worked on at a remote client 102 (Fig. 2). As the workflow
item moves from machine to machine, it carries its context
with it. In other words, the workflow item does not need a
connection to a workflow server to determine its state.
Because the truth maintenance system records all the
justifications, the truth maintenance system 112 can also
provide an explanation of the consequences for the workflow
item. This means that the state of a workflow item at any
time can be determined. Such a feature is particularly useful
in business re-engineering applications.
The present invention may be embodied in other
specific forms without departing from the spirit or essential
characteristics thereof. Certain adaptations and
modifications of the invention will be obvious to those
skilled in the art. Therefore, the presently discussed
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embodiments are considered to be illustrative and not
restrictive, the scope of the invention being indicated by the
appended claims rather than the foregoing description, and all
changes which come within the meaning and range of equivalency
of the claims are therefore intended to be embraced therein.
