29 research outputs found
An adaptive trust based service quality monitoring mechanism for cloud computing
Cloud computing is the newest paradigm in distributed computing that delivers computing resources over the Internet as services. Due to the attractiveness of cloud computing, the market is currently flooded with many service providers. This
has necessitated the customers to identify the right one meeting their requirements in terms of service quality. The existing monitoring of service quality has been limited only to quantification in cloud computing. On the other hand, the continuous
improvement and distribution of service quality scores have been implemented in other distributed computing paradigms but not specifically for cloud computing. This research investigates the methods and proposes mechanisms for quantifying and
ranking the service quality of service providers. The solution proposed in this thesis consists of three mechanisms, namely service quality modeling mechanism, adaptive trust computing mechanism and trust distribution mechanism for cloud computing.
The Design Research Methodology (DRM) has been modified by adding phases, means and methods, and probable outcomes. This modified DRM is used throughout this study. The mechanisms were developed and tested gradually until the expected
outcome has been achieved. A comprehensive set of experiments were carried out in a simulated environment to validate their effectiveness. The evaluation has been carried out by comparing their performance against the combined trust model and
QoS trust model for cloud computing along with the adapted fuzzy theory based trust computing mechanism and super-agent based trust distribution mechanism, which were developed for other distributed systems. The results show that the mechanisms are faster and more stable than the existing solutions in terms of reaching the final trust scores on all three parameters tested. The results presented in this thesis are significant
in terms of making cloud computing acceptable to users in verifying the performance of the service providers before making the selection
Salford postgraduate annual research conference (SPARC) 2012 proceedings
These proceedings bring together a selection of papers from the 2012 Salford Postgraduate Annual Research Conference (SPARC). They reflect the breadth and diversity of research interests showcased at the conference, at which over 130 researchers from Salford, the North West and other UK universities presented their work. 21 papers are collated here from the humanities, arts, social sciences, health, engineering, environment and life sciences, built environment and business
A Two-Level Information Modelling Translation Methodology and Framework to Achieve Semantic Interoperability in Constrained GeoObservational Sensor Systems
As geographical observational data capture, storage and sharing technologies such as in situ remote monitoring systems and spatial data infrastructures evolve, the vision of a Digital Earth, first articulated by Al Gore in 1998 is getting ever closer. However, there are still many challenges and open research questions. For example, data quality, provenance and heterogeneity remain an issue due to the complexity of geo-spatial data and information representation.
Observational data are often inadequately semantically enriched by geo-observational information systems or spatial data infrastructures and so they often do not fully capture the true meaning of the associated datasets. Furthermore, data models underpinning these information systems are typically too rigid in their data representation to allow for the ever-changing and evolving nature of geo-spatial domain concepts. This impoverished approach to observational data representation reduces the ability of multi-disciplinary practitioners to share information in an interoperable and computable way.
The health domain experiences similar challenges with representing complex and evolving domain information concepts. Within any complex domain (such as Earth system science or health) two categories or levels of domain concepts exist. Those concepts that remain stable over a long period of time, and those concepts that are prone to change, as the domain knowledge evolves, and new discoveries are made. Health informaticians have developed a sophisticated two-level modelling systems design approach for electronic health documentation over many years, and with the use of archetypes, have shown how data, information, and knowledge interoperability among heterogenous systems can be achieved.
This research investigates whether two-level modelling can be translated from the health domain to the geo-spatial domain and applied to observing scenarios to achieve semantic interoperability within and between spatial data infrastructures, beyond what is possible with current state-of-the-art approaches.
A detailed review of state-of-the-art SDIs, geo-spatial standards and the two-level modelling methodology was performed. A cross-domain translation methodology was developed, and a proof-of-concept geo-spatial two-level modelling framework was defined and implemented. The Open Geospatial Consortium’s (OGC) Observations & Measurements (O&M) standard was re-profiled to aid investigation of the two-level information modelling approach. An evaluation of the method was undertaken using II specific use-case scenarios. Information modelling was performed using the two-level modelling method to show how existing historical ocean observing datasets can be expressed semantically and harmonized using two-level modelling. Also, the flexibility of the approach was investigated by applying the method to an air quality monitoring scenario using a technologically constrained monitoring sensor system.
This work has demonstrated that two-level modelling can be translated to the geospatial domain and then further developed to be used within a constrained technological sensor system; using traditional wireless sensor networks, semantic web technologies and Internet of Things based technologies. Domain specific evaluation results show that twolevel modelling presents a viable approach to achieve semantic interoperability between constrained geo-observational sensor systems and spatial data infrastructures for ocean observing and city based air quality observing scenarios. This has been demonstrated through the re-purposing of selected, existing geospatial data models and standards. However, it was found that re-using existing standards requires careful ontological analysis per domain concept and so caution is recommended in assuming the wider applicability of the approach.
While the benefits of adopting a two-level information modelling approach to geospatial information modelling are potentially great, it was found that translation to a new domain is complex. The complexity of the approach was found to be a barrier to adoption, especially in commercial based projects where standards implementation is low on implementation road maps and the perceived benefits of standards adherence are low. Arising from this work, a novel set of base software components, methods and fundamental geo-archetypes have been developed. However, during this work it was not possible to form the required rich community of supporters to fully validate geoarchetypes. Therefore, the findings of this work are not exhaustive, and the archetype models produced are only indicative. The findings of this work can be used as the basis to encourage further investigation and uptake of two-level modelling within the Earth system science and geo-spatial domain. Ultimately, the outcomes of this work are to recommend further development and evaluation of the approach, building on the positive results thus far, and the base software artefacts developed to support the approach
Factories of the Future
Engineering; Industrial engineering; Production engineerin
Design for energy-efficient and reliable fog-assisted healthcare IoT systems
Cardiovascular disease and diabetes are two of the most dangerous diseases as they are the leading causes of death in all ages. Unfortunately, they cannot be completely cured with the current knowledge and existing technologies. However, they can be effectively managed by applying methods of continuous health monitoring. Nonetheless, it is difficult to achieve a high quality of healthcare with the current health monitoring systems which often have several limitations such as non-mobility support, energy inefficiency, and an insufficiency of advanced services. Therefore, this thesis presents a Fog computing approach focusing on four main tracks, and proposes it as a solution to the existing limitations. In the first track, the main goal is to introduce Fog computing and Fog services into remote health monitoring systems in order to enhance the quality of healthcare.
In the second track, a Fog approach providing mobility support in a real-time health monitoring IoT system is proposed. The handover mechanism run by Fog-assisted smart gateways helps to maintain the connection between sensor nodes and the gateways with a minimized latency. Results show that the handover latency of the proposed Fog approach is 10%-50% less than other state-of-the-art mobility support approaches.
In the third track, the designs of four energy-efficient health monitoring IoT systems are discussed and developed. Each energy-efficient system and its sensor nodes are designed to serve a specific purpose such as glucose monitoring, ECG monitoring, or fall detection; with the exception of the fourth system which is an advanced and combined system for simultaneously monitoring many diseases such as diabetes and cardiovascular disease. Results show that these sensor nodes can continuously work, depending on the application, up to 70-155 hours when using a 1000 mAh lithium battery.
The fourth track mentioned above, provides a Fog-assisted remote health monitoring IoT system for diabetic patients with cardiovascular disease. Via several proposed algorithms such as QT interval extraction, activity status categorization, and fall detection algorithms, the system can process data and detect abnormalities in real-time. Results show that the proposed system using Fog services is a promising approach for improving the treatment of diabetic patients with cardiovascular disease
Discovery and Group Communication for Constrained Internet of Things Devices using the Constrained Application Protocol
The ubiquitous Internet is rapidly spreading to new domains. This expansion of
the Internet is comparable in scale to the spread of the Internet in the ’90s. The
resulting Internet is now commonly referred to as the Internet of Things (IoT) and
is expected to connect about 50 billion devices by the year 2020. This means that
in just five years from the time of writing this PhD the number of interconnected
devices will exceed the number of humans by sevenfold. It is further expected that
the majority of these IoT devices will be resource constrained embedded devices
such as sensors and actuators. Sensors collect information about the physical world
and inject this information into the virtual world. Next processing and reasoning
can occur and decisions can be taken to enact upon the physical world by injecting
feedback to actuators.
The integration of embedded devices into the Internet introduces new challenges,
since many of the existing Internet technologies and protocols were not
designed for this class of constrained devices. These devices are typically optimized
for low cost and power consumption and thus have very limited power,
memory, and processing resources and have long sleep periods. The networks
formed by these embedded devices are also constrained and have different characteristics
than those typical in todays Internet. These constrained networks have
high packet loss, low throughput, frequent topology changes and small useful payload
sizes. They are referred to as LLN. Therefore, it is in most cases unfeasible to
run standard Internet protocols on this class of constrained devices and/or LLNs.
New or adapted protocols that take into consideration the capabilities of the constrained
devices and the characteristics of LLNs, are required.
In the past few years, there were many efforts to enable the extension of the
Internet technologies to constrained devices. Initially, most of these efforts were
focusing on the networking layer. However, the expansion of the Internet in the
90s was not due to introducing new or better networking protocols. It was a result
of introducing the World Wide Web (WWW), which made it easy to integrate services
and applications. One of the essential technologies underpinning the WWW
was the Hypertext Transfer Protocol (HTTP). Today, HTTP has become a key
protocol in the realization of scalable web services building around the Representational
State Transfer (REST) paradigm. The REST architectural style enables
the realization of scalable and well-performing services using uniform and simple
interfaces. The availability of an embedded counterpart of HTTP and the REST
architecture could boost the uptake of the IoT.
Therefore, more recently, work started to allow the integration of constrained
devices in the Internet at the service level. The Internet Engineering Task Force
(IETF) Constrained RESTful Environments (CoRE) working group has realized
the REST architecture in a suitable form for the most constrained nodes and networks.
To that end the Constrained Application Protocol (CoAP) was introduced,
a specialized RESTful web transfer protocol for use with constrained networks and
nodes. CoAP realizes a subset of the REST mechanisms offered by HTTP, but is
optimized for Machine-to-Machine (M2M) applications.
This PhD research builds upon CoAP to enable a better integration of constrained
devices in the IoT and examines proposed CoAP solutions theoretically
and experimentally proposing alternatives when appropriate. The first part of this
PhD proposes a mechanism that facilitates the deployment of sensor networks
and enables the discovery, end-to-end connectivity and service usage of newly
deployed sensor nodes. The proposed approach makes use of CoAP and combines
it with Domain Name System (DNS) in order to enable the use of userfriendly
Fully Qualified Domain Names (FQDNs) for addressing sensor nodes. It
includes the automatic discovery of sensors and sensor gateways and the translation
of HTTP to CoAP, thus making the sensor resources globally discoverable and
accessible from any Internet-connected client using either IPv6 addresses or DNS
names both via HTTP or CoAP. As such, the proposed approach provides a feasible
and flexible solution to achieve hierarchical self-organization with a minimum
of pre-configuration. By doing so we minimize costly human interventions and
eliminate the need for introducing new protocols dedicated for the discovery and
organization of resources. This reduces both cost and the implementation footprint
on the constrained devices.
The second, larger, part of this PhD focuses on using CoAP to realize communication
with groups of resources. In many IoT application domains, sensors
or actuators need to be addressed as groups rather than individually, since individual
resources might not be sufficient or useful. A simple example is that all
lights in a room should go on or off as a result of the user toggling the light switch.
As not all IoT applications may need group communication, the CoRE working
group did not include it in the base CoAP specification. This way the base protocol
is kept as efficient and as simple as possible so it would run on even the most
constrained devices. Group communication and other features that might not be
needed by all devices are standardized in a set of optional separate extensions. We
first examined the proposed CoAP extension for group communication, which utilizes
Internet Protocol version 6 (IPv6) multicasts. We highlight its strengths and
weaknesses and propose our own complementary solution that uses unicast to realize
group communication. Our solution offers capabilities beyond simple group
communication. For example, we provide a validation mechanism that performs
several checks on the group members, to make sure that combining them together
is possible. We also allow the client to request that results of the individual members
are processed before they are sent to the client. For example, the client can
request to obtain only the maximum value of all individual members.
Another important optional extension to CoAP allows clients to continuously
observe resources by registering their interest in receiving notifications from CoAP
servers once there are changes to the values of the observed resources. By using
this publish/subscribe mechanism the client does not need to continuously poll the
resource to find out whether it has changed its value. This typically leads to more
efficient communication patterns that preserve valuable device and LLN resources.
Unfortunately CoAP observe does not work together with the CoAP group communication
extension, since the observe extension assumes unicast communication
while the group communication extension only support multicast communication.
In this PhD we propose to extend our own group communication solution to offer
group observation capabilities. By combining group observation with group
processing features, it becomes possible to notify the client only about certain
changes to the observed group (e.g., the maximum value of all group members has
changed).
Acknowledging that the use of multicast as well as unicast has strengths and
weaknesses we propose to extend our unicast based solution with certain multicast
features. By doing so we try to combine the strengths of both approaches to obtain
a better overall group communication that is flexible and that can be tailored
according to the use case needs.
Together, the proposed mechanisms represent a powerful and comprehensive
solution to the challenging problem of group communication with constrained devices.
We have evaluated the solutions proposed in this PhD extensively and in
a variety of forms. Where possible, we have derived theoretical models and have
conducted numerous simulations to validate them. We have also experimentally
evaluated those solutions and compared them with other proposed solutions using
a small demo box and later on two large scale wireless sensor testbeds and under
different test conditions. The first testbed is located in a large, shielded room,
which allows testing under controlled environments. The second testbed is located
inside an operational office building and thus allows testing under normal operation
conditions. Those tests revealed performance issues and some other problems.
We have provided some solutions and suggestions for tackling those problems.
Apart from the main contributions, two other relevant outcomes of this PhD are
described in the appendices. In the first appendix we review the most important
IETF standardization efforts related to the IoT and show that with the introduction
of CoAP a complete set of standard protocols has become available to cover the
complete networking stack and thus making the step from the IoT into the Web
of Things (WoT). Using only standard protocols makes it possible to integrate
devices from various vendors into one bigWoT accessible to humans and machines
alike.
In the second appendix, we provide an alternative solution for grouping constrained
devices by using virtualization techniques. Our approach focuses on the
objects, both resource-constrained and non-constrained, that need to cooperate
by integrating them into a secured virtual network, named an Internet of Things
Virtual Network or IoT-VN. Inside this IoT-VN full end-to-end communication
can take place through the use of protocols that take the limitations of the most
resource-constrained devices into account. We describe how this concept maps to
several generic use cases and, as such, can constitute a valid alternative approach
for supporting selected applications
Discovery and group communication for constrained Internet of Things devices using the Constrained Application Protocol
The ubiquitous Internet is rapidly spreading to new domains. This expansion of
the Internet is comparable in scale to the spread of the Internet in the ’90s. The
resulting Internet is now commonly referred to as the Internet of Things (IoT) and
is expected to connect about 50 billion devices by the year 2020. This means that
in just five years from the time of writing this PhD the number of interconnected
devices will exceed the number of humans by sevenfold. It is further expected that
the majority of these IoT devices will be resource constrained embedded devices
such as sensors and actuators. Sensors collect information about the physical world
and inject this information into the virtual world. Next processing and reasoning
can occur and decisions can be taken to enact upon the physical world by injecting
feedback to actuators.
The integration of embedded devices into the Internet introduces new challenges,
since many of the existing Internet technologies and protocols were not
designed for this class of constrained devices. These devices are typically optimized
for low cost and power consumption and thus have very limited power,
memory, and processing resources and have long sleep periods. The networks
formed by these embedded devices are also constrained and have different characteristics
than those typical in todays Internet. These constrained networks have
high packet loss, low throughput, frequent topology changes and small useful payload
sizes. They are referred to as LLN. Therefore, it is in most cases unfeasible to
run standard Internet protocols on this class of constrained devices and/or LLNs.
New or adapted protocols that take into consideration the capabilities of the constrained
devices and the characteristics of LLNs, are required.
In the past few years, there were many efforts to enable the extension of the
Internet technologies to constrained devices. Initially, most of these efforts were
focusing on the networking layer. However, the expansion of the Internet in the
90s was not due to introducing new or better networking protocols. It was a result
of introducing the World Wide Web (WWW), which made it easy to integrate services
and applications. One of the essential technologies underpinning the WWW
was the Hypertext Transfer Protocol (HTTP). Today, HTTP has become a key
protocol in the realization of scalable web services building around the Representational
State Transfer (REST) paradigm. The REST architectural style enables
the realization of scalable and well-performing services using uniform and simple
interfaces. The availability of an embedded counterpart of HTTP and the REST
architecture could boost the uptake of the IoT.
Therefore, more recently, work started to allow the integration of constrained
devices in the Internet at the service level. The Internet Engineering Task Force
(IETF) Constrained RESTful Environments (CoRE) working group has realized
the REST architecture in a suitable form for the most constrained nodes and networks.
To that end the Constrained Application Protocol (CoAP) was introduced,
a specialized RESTful web transfer protocol for use with constrained networks and
nodes. CoAP realizes a subset of the REST mechanisms offered by HTTP, but is
optimized for Machine-to-Machine (M2M) applications.
This PhD research builds upon CoAP to enable a better integration of constrained
devices in the IoT and examines proposed CoAP solutions theoretically
and experimentally proposing alternatives when appropriate. The first part of this
PhD proposes a mechanism that facilitates the deployment of sensor networks
and enables the discovery, end-to-end connectivity and service usage of newly
deployed sensor nodes. The proposed approach makes use of CoAP and combines
it with Domain Name System (DNS) in order to enable the use of userfriendly
Fully Qualified Domain Names (FQDNs) for addressing sensor nodes. It
includes the automatic discovery of sensors and sensor gateways and the translation
of HTTP to CoAP, thus making the sensor resources globally discoverable and
accessible from any Internet-connected client using either IPv6 addresses or DNS
names both via HTTP or CoAP. As such, the proposed approach provides a feasible
and flexible solution to achieve hierarchical self-organization with a minimum
of pre-configuration. By doing so we minimize costly human interventions and
eliminate the need for introducing new protocols dedicated for the discovery and
organization of resources. This reduces both cost and the implementation footprint
on the constrained devices.
The second, larger, part of this PhD focuses on using CoAP to realize communication
with groups of resources. In many IoT application domains, sensors
or actuators need to be addressed as groups rather than individually, since individual
resources might not be sufficient or useful. A simple example is that all
lights in a room should go on or off as a result of the user toggling the light switch.
As not all IoT applications may need group communication, the CoRE working
group did not include it in the base CoAP specification. This way the base protocol
is kept as efficient and as simple as possible so it would run on even the most
constrained devices. Group communication and other features that might not be
needed by all devices are standardized in a set of optional separate extensions. We
first examined the proposed CoAP extension for group communication, which utilizes
Internet Protocol version 6 (IPv6) multicasts. We highlight its strengths and
weaknesses and propose our own complementary solution that uses unicast to realize
group communication. Our solution offers capabilities beyond simple group
communication. For example, we provide a validation mechanism that performs
several checks on the group members, to make sure that combining them together
is possible. We also allow the client to request that results of the individual members
are processed before they are sent to the client. For example, the client can
request to obtain only the maximum value of all individual members.
Another important optional extension to CoAP allows clients to continuously
observe resources by registering their interest in receiving notifications from CoAP
servers once there are changes to the values of the observed resources. By using
this publish/subscribe mechanism the client does not need to continuously poll the
resource to find out whether it has changed its value. This typically leads to more
efficient communication patterns that preserve valuable device and LLN resources.
Unfortunately CoAP observe does not work together with the CoAP group communication
extension, since the observe extension assumes unicast communication
while the group communication extension only support multicast communication.
In this PhD we propose to extend our own group communication solution to offer
group observation capabilities. By combining group observation with group
processing features, it becomes possible to notify the client only about certain
changes to the observed group (e.g., the maximum value of all group members has
changed).
Acknowledging that the use of multicast as well as unicast has strengths and
weaknesses we propose to extend our unicast based solution with certain multicast
features. By doing so we try to combine the strengths of both approaches to obtain
a better overall group communication that is flexible and that can be tailored
according to the use case needs.
Together, the proposed mechanisms represent a powerful and comprehensive
solution to the challenging problem of group communication with constrained devices.
We have evaluated the solutions proposed in this PhD extensively and in
a variety of forms. Where possible, we have derived theoretical models and have
conducted numerous simulations to validate them. We have also experimentally
evaluated those solutions and compared them with other proposed solutions using
a small demo box and later on two large scale wireless sensor testbeds and under
different test conditions. The first testbed is located in a large, shielded room,
which allows testing under controlled environments. The second testbed is located
inside an operational office building and thus allows testing under normal operation
conditions. Those tests revealed performance issues and some other problems.
We have provided some solutions and suggestions for tackling those problems.
Apart from the main contributions, two other relevant outcomes of this PhD are
described in the appendices. In the first appendix we review the most important
IETF standardization efforts related to the IoT and show that with the introduction
of CoAP a complete set of standard protocols has become available to cover the
complete networking stack and thus making the step from the IoT into the Web
of Things (WoT). Using only standard protocols makes it possible to integrate
devices from various vendors into one bigWoT accessible to humans and machines
alike.
In the second appendix, we provide an alternative solution for grouping constrained
devices by using virtualization techniques. Our approach focuses on the
objects, both resource-constrained and non-constrained, that need to cooperate
by integrating them into a secured virtual network, named an Internet of Things
Virtual Network or IoT-VN. Inside this IoT-VN full end-to-end communication
can take place through the use of protocols that take the limitations of the most
resource-constrained devices into account. We describe how this concept maps to
several generic use cases and, as such, can constitute a valid alternative approach
for supporting selected applications