WMS systems manage and coordinate several independent
subtasks. The coordination problems get even more serious when
the subtasks are performed on separate systems.
SYSTEM ARCHITECTURE FOR WMS :
.
1) The flow of information in an organization occurs by means of
documents (e.g., purchase order request, travel authorization
request, etc.), which are passed through various individuals. Each
individual performs operations on the document such as: fill in
some fields, modify fields, etc.
2) This form then goes to a secretary who reviews it, and enters
information on previous business travel by the employee.
3) Next, the form is sent to the manager who approves or
disapproves the requested amount. Alternatively, the manager
may approve a smaller amount than requested.
4)
Finally, the form is returned to the individual concerned and the
secretary to notify them of the decision.
PROBLEMS :

CONTROL

AUTHORIZATION
Three techniques for handling workflow control & authorization:
1) workflow control matrices : defines the relationship between two
operations that can be performed in a temporal sense.
2) sequence constraints : consists of techniques for imposing and
enforcing constraints on the routing sequence of the workflow, i.e.,
the sequence in which a document is sent to various employees
3) event-based constraints : event-based constraints which can be
used to specify unusual routing needs and other special actions.
These techniques can :
 can exploit parallelism,
 lead to more efficient processes
 Do better workflow systems
 can handle various kinds of exception situations that arise in
workflow applications.
The objective of our framework is to complete a list of tasks with
respect to each document subject to a set of sequence constraints
while providing support for dynamic routing and operational
integrity control.
Dynamic routing : routing a document in a dynamic manner subject
to certain constraints. There is no predefined order as in static
routing.
Operational integrity control : refers to imposing restrictions on
the permissibility of various operations that may be performed on
various fields of a document by different individuals as the
document travels through the organization.
The WMS routes the documents to work baskets while workers
interact with the documents through the work baskets
assigned them.
Three types of work baskets:
 document-based : each basket contains a particular type of
document, and every worker accesses the same document in the
same basket & are hard to use for routing documents.
 worker-based : contain all documents assigned to the same
worker. Routing of documents can be done after a document is
processed by moving documents from the basket of one worker to
the basket of another. inflexible as modification to the routing
mechanism is needed when a worker is absent or leaves the
company.
 rolebased : contains similar documents that must be worked upon
by workers performing a specific role. Any worker belonging to
that role can process the documents in the basket. When a worker
starts processing a document, the document is locked so that no
one else can access it. Role-based baskets are most suitable for
supporting dynamic routing because no change to the routing
mechanism is needed when a worker leaves the system or is
reassigned.
The following terms to describe the workflow process and to
develop the control and authorization mechanisms.
1)
document (d): A statement or form that is needed for a business
transaction, e.g., a billing statement or a travel authorization
form.
2) field (f): Any data element contained in a document that has a
numerical or symbolic value.
3)
worker (w): Any person who performs operations on documents
using the workflow management system.
4)
roLe (r): A generic identifier for a group of workers, any one of
whom may perform a task assigned to the “role”.
5)
work basket (b): A unique, logical box associated with a role. Each
work basket contains a stack (or queue) of documents waiting to
be processed by a worker in the corresponding role.
6)
operation (0): The smallest unit of work, e.g.,enter a data value
into the amount field on a form.
7) Tusk (t): A collection of operations that corresponds to a step in a
common business process, e.g., fill in the customer request form.
8) sequence dependency (s): Two tasks that must be performed by
different roles in a given sequence create a sequence
dependency.

Proper routing of documents to various workers is by far the
most important function of the workflow management system & is
achieved by means of sequence constraints that impose
dependencies between tasks on a document. The proper routing
of a document is achieved by controlling the sequence in which a
document is accessed by various roles.
The operational integrity is maintained by placing restrictions on
the kinds of operations (e.g., read, enter, modify, etc.) that a
worker in a given role is allowed to perform on fields of a
document. This is done by keeping a workflow control matrix that
specifies the permissible operations that can be performed by a
given role. Once a document is accessed by a worker, he or she
will be notified of the permissible operations by the system.
Eventbased constraints can be used to trigger special actions to
take place especially when an unusual event Occurs.
The workflow manager moves the documents among the
baskets after each task is completed by consulting the control
matrices, the sequence constraints, and the event-based
constraints. This is how the system does automatic
authorization and control of access and operations.
The workflow control matrix restricts the operations that a worker
in a certain role may perform on a document. This matrix is
sequence independent but it is possible to enforce a sequence of
operations between a pair of employees.
An alternative, and possibly more concise, way of specifying the
permissions is by means of explicit statements such as:
Permission([ROLE].DOC[.FIELD].[OP] )=y /n.


The default value of all permissions would be “n”, unless
explicitly overridden by a permission statement.
If the role entry (in the above syntax) is missing, then the
statement would apply to all roles.
Similarly, if the field or operation entry is missing, the statement
would apply to all fields or operations.
When a document moves within the organization, the sequence in
which changes (or updates) are made to it is recorded, and is
called the document history. If the exact sequence that a document
must take each time is known before hand, it can be specified as a
complete ordering; however, in general, the sequence can change
because alternative paths might be acceptable, certain steps
might not be essential, or an employee might be absent, etc.
Therefore, the goal of sequence maintenance is to provide a
mechanism whereby a set of constraints can be used to define a
partial ordering on the document history and the workflow
management system would enforce those constraints. A document
history is considered legitimute or admisszble if none of the
constraints is violated.
Classified as :
(1) time-based condition based on elapsed time eg :
IF AGE(doc1D) > 10 THEN
SEND(doclD,*,blO)
(2) access pattern of a document eg :
IF REWORK(w5,docID) = 5 THEN
NOTIFY(docID, “rework 5 times” ,w5, bll)
(3) combination of access pattern and elapsed time eg :
IF AGE(doc1D) > 10 AND
SEND( docID ,*,b10).
REWORK(w5,docID) >2 THEN
(4) special conditions that depend upon field values eg :
IF VALUE(docID.fl) > 10000 THEN
ROUTE( docID ,b 10)
(5) special conditions that depend upon changes made to
field values eg
IF
INC(docID.fl) > 5000 THEN
ROUT E (do CID, b 10).
THANK YOU !!