PSTEP: A Novel Probabilistic Event Processing
Language for Uncertain Spatio-Temporal Event
Streams of Internet of Vehicles
Huiyong Li, Yuanrui Zhang, Yixiang Chen
MoE Engineering Research Center for
Software/Hardware Co-design Technology and Application
East China Normal University
Shanghai 200062, P.R.China
Email: yxchen@sei.ecnu.edu.cn
Abstract—Internet of Vehicles (IoV, shortly) is a typical system
of Internet of Things. Spatio-Temporal event stream is one of
basic features of IoV. These event streams often are uncertain
due to the limit of the monitoring device and the high speed of
vehicles. Developing an event processing language to process these
spatio-temporal event streams with uncertainty is a challenge
issue. The goal of this paper is to develop a Probabilistic Event
Processing Language, called as Probabilistic Spatio-Temporal
Event Processing language (PSTEP, shortly), dealing with this
challenge issue. In PSTEP, we use the Possible World Model to
express uncertain spatio-temporal events of IoV and assign a
spatio-temporal event with a probability which is the threshold
value for processing the existence of an event. We establish its
syntax and operational semantics. Finally, a case study is given
to show the effectiveness of the PSTEP language.
Keywords—Event Processing Language, Uncertain Event, For-
mal Semantics, Event-Driven Architecture, Internet of Vehicles,
Mobile System, Internet of Things.
I. INTRODUCTION
In recent years, there are many achievements in the re-
search of Internet of Vehicles (IoV, shortly) [1]. The IoV is a
kind of typical mobile system and Internet of Things system. In
IoV system, monitoring devices monitor the moving vehicles
and gather temporal and spatial data streams.
Some scholars use the complex event processing technol-
ogy to process the data steams of IoV. Moody K. proposes
a complex event query language SpaTec which describes
the spatial and temporal properties of the event instances
of IoV [2, 3]. Jin B. proposes an event query language
CPSL which describes the relationship between the various
temporal and spatial properties of the event of IoV [4]. In
this technology, the data of systems are abstracted as event
instances and users can process these event instances by using
event processing language.
These languages assume that the data and event instances of
IoV are certain. However, we sometimes can only get uncertain
data. This is because that the data source is not certain. The
precision of data collecting devices is limited, for example, var-
ious types of monitoring devices, RFID scanning equipments
and GPS equipments have different accuracy. According to
statistics, the probability that the RFID tags can be correctly
recognized is only about 60% to 70%. So these uncertain data
in the IoV system are ubiquitous and can not be ignored.
Since the existing complex event processing languages
can not effectively express and process the uncertain event
instances of IoV, this paper proposes a novel probabilistic com-
plex event processing language: Probabilistic Spatio-Temporal
Event Processing language (PSTEP, shortly). The remainder
of this paper is structured as follows: Section II states the
related works. Section III describes the Possible World Model
of IoV’s uncertain event instance. Section IV introduces the
syntax of PSTEP. Section V gives the operational semantics
of PSTEP. Section VI shows the effectiveness of the PSTEP
by an example. The last one is the concluding section.
II. R
ELATED WORKS
In the event-driven architecture systems, data are abstracted
as the event instance. So the uncertain data are abstracted as
the uncertain event instances. In the study of the uncertain
events’s model, there are two types of uncertain event model:
the Probability Theory Model [5–7] and the Fuzzy Set Theory
Model [8–10]. The Possible World Model belongs to the Prob-
ability Theory Model [11, 12]. In this model, the probability
of data denoted its possibility.
For the uncertain data processing problem, the current
research works focus on the fields of uncertain database.
Many scholars have deeply researched the uncertain database
technology such as storing, indexing and querying. Since the
data streams arrive very fast and its amount is very large.
The data stream processing system will not directly use the
methods and techniques of the conventional database system.
Compared with the uncertain database’s research, the study
of uncertain data stream processing system needs to develop
still. Cormode proposes the uncertain data stream query system
with probability parameters [13]. Zhang designs the frequent
query on uncertain data stream query method [14]. As an
important uncertain data processing area, the uncertain event
stream processing system has some achievements: Kanagal
has extended the relational database system in order to deal
with uncertain event streams [15]. Christopher has proposed an
uncertain event stream processing system named Lahar [16].
2015 IEEE International Conference on Software Quality, Reliability and Security Companion
/15 $31.00 © 2015 IEEE
DOI 10.1109/QRS-C.2015.43
161
2015 IEEE International Conference on Software Quality, Reliability and Security Companion
/15 $31.00 © 2015 IEEE
DOI 10.1109/QRS-C.2015.43
161
2015 IEEE International Conference on Software Quality, Reliability and Security Companion
/15 $31.00 © 2015 IEEE
DOI 10.1109/QRS-C.2015.43
161