Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
2001-05-03
2004-10-19
Mizrahi, Diane D. (Department: 2175)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000
Reexamination Certificate
active
06807547
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to computing systems which utilize Enterprise JavaBeans. More particularly, the present invention relates to timers for state machines which are implemented as Enterprise JavaBeans.
2. Description of the Related Art
The Java 2 Platform, Enterprise Edition (J2EE) is an industry-standard general purpose platform for the development of enterprise business applications. Enterprise business applications include applications for purchase order management or transactions processing. As a part of J2EE, application logic may be implemented using the Enterprise JavaBeans (EJB) component model which provides application development tools for application developers.
In general, an EJB component model is a component architecture for the development and the deployment of object-oriented, distributed, enterprise-level applications. An application developed using the EJB component model is scalable and transactional, and is typically portable across multiple platforms, which enables an EJB component to effectively be “written once” and “used substantially anywhere.” That is, EJB components may also be used by multiple applications, i.e., EJB components may be shared or reused. As will be understood by those skilled in the art, the EJB component model enables application development to be simplified due, at least in part, to the fact that typically difficult programming problems are implemented by an EJB container, and not the application.
Some applications utilize state machines, or are designed to use the concept of a state machine in their implementation, and have generally not been developed using J2EE. Specifically, there has been a perceived mismatch between the J2EE programming model and requirements associated with state machines. A state machine may be considered to be a behavior that specifies the sequences of states that an object goes through during its lifetime in response to events, in addition to its responses to those events. A state of an object is a condition or a situation during the lifetime of an object which satisfies some condition, performs some activity, or waits for one or more events. An event is the specification of an occurrence that has a location in time or space that may trigger a state transition associated with the object.
Applications which use state machines include telecommunications, or “telecom,” applications. Typically, within telecom applications, each telecom vendor uses its own proprietary technique to implement state machines. A state machine which may be used in a telecom application is shown in FIG.
1
.
FIG. 1
illustrates a state machine that is associated with a base station controller in a cellular telecom network. A cellular network
100
includes a mobile station (MS)
102
, a base transmittal station (BTS)
104
, a base station controller
106
, and a mobile switching center
108
. MS
102
may be substantially any device which is suitable for use within cellular network
100
, e.g., MS
102
may be a cellular telephone. BTS
104
generally includes radio equipment that controls a cell within cellular network
100
. BSC
106
is a telecom application that provides the implementation of call control logic, such as the logic for the setup and the termination of connections. MSC
108
includes telecom equipment that handles the traffic, e.g., voice traffic, of established connections.
BSC
106
or, more specifically, the telecom application associated with BSC
106
, is generally implemented as a connection state machine
114
or a set of connection state machines. Connection state machine
114
implements the protocol for the setup of, and the termination of, connections between MS
102
and MSC
108
.
The connection setup and termination protocol generally begins when MS
104
requests a connection by sending a RequestConnection event
118
to BTS
104
. BTS
104
then sends RequestConnection event
118
′ to BSC
106
, which causes a connection state machine object to be created within BSC
106
or, more specifically, the telecom application within BSC
106
.
Upon creating a connection state machine object, connection state machine
114
sends an AllocateResources event
122
to MSC
108
to essentially request that MSC
108
allocate resources for voice traffic. Once MSC
108
has allocated the resources as requested, MSC
108
generates a ResourcesAllocated event
124
which is sent to BSC
106
and indicates that resources have been allocated.
After receiving ResourcesAllocated event
124
from MSC
108
, BSC
106
or, more specifically, connection state machine
114
sends a ConnectionEstablished event
128
to BTS
104
indicating that a connection has been established in response to a request from MS
102
. In response to receiving ConnectionEstablished event
128
, BTS
104
sends ConnectionEstablished event
128
′ to MS
102
such that MS
102
is notified of an established connection.
When MS
102
no longer needs a connection, i.e., once MS
104
has completed its use of a connection, MS
102
may “hang up” on the connection. When MS
104
hangs up on the connection, MS
102
sends a TerminateConnection event
132
to BTS
104
. Upon receipt of TerminateConnection event
132
by BTS
104
, BTS
104
sends TerminateConnection event
132
′ to BSC
106
and, hence, connection state machine
114
. Connection state machine
114
, in turn, sends a DeallocateResources event
136
to MSC
108
, which deallocates voice traffic resources, and sends a ResourcesDeallocated event
140
to BSC
106
. It should be appreciated that once BSC
106
receives ResourcesDeallocated event
140
, BSC
114
deletes the state machine object it allocated in response to RequestConnection event
118
′.
FIG. 2
is a state chart diagram which illustrates an algorithm of a connection state machine, e.g., state machine
114
of FIG.
1
. That is,
FIG. 2
is an algorithmic representation of an overall connection process associated with cellular network
100
of
FIG. 1. A
process of implementing a connection begins at step
202
in which a connection is requested. The request for a connection results in the creation of a connection state machine object. Once a connection is requested, allocation of resources is effectively requested in step
202
, and resources for the connection are allocated in step
204
, e.g., for voice traffic in a cellular telecommunications network. When resources are allocated, voice traffic is allowed to “flow” over the cellular telecommunications network. Once the connection is no longer needed, the connection is terminated in step
210
, and the deallocation of resources allocated to the connection is commenced in step
212
. After resources are deallocated in step
214
, the process of implementing a connection concludes.
In the course of allocating resources, timeouts may occur, as will be appreciated by those skilled in the art. When timeouts occur during the allocation of resources or the deallocation of resources, cleanups occur, as for example in steps
216
and
218
. Once cleanups have occurred, the process of implementing a connection is terminated.
A state machine generally uses timers to bound the time interval in which the state machine exists in a particular state. Typically, a state machine enters a state with an expectation that it will receive an external event within a specified time interval. To ensure that a state machine does not wait for too prolonged a time for the external event to occur, the state machine may create a timer that is in tact over the course of the specified time interval. When an external event occurs prior to the expiration of the timer, then the state machine cancels the timer. Alternatively, when an external event does not occur prior to the expiration of the timer, i.e., when the timer expires, the state machine is signaled. Typically, the state machine is signaled to proceed to a new state.
A timer service typically provides a timer creation method that uses a time duration, expi
Hapner Mark W.
Matena Vladimir
Beyer Weaver & Thomas LLP
Mizrahi Diane D.
Sun Microsystems Inc.
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