97,279 research outputs found
A Home Automation Prototype
This master thesis concerns the current and future development in the area of intelligent houses and home automation. It also describes a system for home automation developed for this thesis. Key words in the design are dynamic behaviour, flexibility, transparency and adaptability. The prototype has been built with a central, Java based, server. To this server, modules handling different communication protocols can be connected at run time. To these modules, devices can connect over the specified communications protocols and register in the server, also at run time. Devices can be for control and supervision (computer or phone GUI), but also equipment that is to be controlled (lamps, ventilation, stereo) and equipment for notification (sensors). For communication, a message system has been developed. The server uses a MySQL database and also has support for building macros with extensive command and timer functionality. Finally, the system supports users and positioning using RFID
Dynamic proofs of retrievability with low server storage
Proofs of Retrievability (PoRs) are protocols which allow a client to store
data remotely and to efficiently ensure, via audits, that the entirety of that
data is still intact. A dynamic PoR system also supports efficient retrieval
and update of any small portion of the data. We propose new, simple protocols
for dynamic PoR that are designed for practical efficiency, trading decreased
persistent storage for increased server computation, and show in fact that this
tradeoff is inherent via a lower bound proof of time-space for any PoR scheme.
Notably, ours is the first dynamic PoR which does not require any special
encoding of the data stored on the server, meaning it can be trivially composed
with any database service or with existing techniques for encryption or
redundancy. Our implementation and deployment on Google Cloud Platform
demonstrates our solution is scalable: for example, auditing a 1TB file takes
just less than 5 minutes and costs less than $0.08 USD. We also present several
further enhancements, reducing the amount of client storage, or the
communication bandwidth, or allowing public verifiability, wherein any
untrusted third party may conduct an audit
System Design of Internet-of-Things for Residential Smart Grid
Internet-of-Things (IoTs) envisions to integrate, coordinate, communicate,
and collaborate real-world objects in order to perform daily tasks in a more
intelligent and efficient manner. To comprehend this vision, this paper studies
the design of a large scale IoT system for smart grid application, which
constitutes a large number of home users and has the requirement of fast
response time. In particular, we focus on the messaging protocol of a universal
IoT home gateway, where our cloud enabled system consists of a backend server,
unified home gateway (UHG) at the end users, and user interface for mobile
devices. We discuss the features of such IoT system to support a large scale
deployment with a UHG and real-time residential smart grid applications. Based
on the requirements, we design an IoT system using the XMPP protocol, and
implemented in a testbed for energy management applications. To show the
effectiveness of the designed testbed, we present some results using the
proposed IoT architecture.Comment: 10 pages, 6 figures, journal pape
Theory and Practice of Transactional Method Caching
Nowadays, tiered architectures are widely accepted for constructing large
scale information systems. In this context application servers often form the
bottleneck for a system's efficiency. An application server exposes an object
oriented interface consisting of set of methods which are accessed by
potentially remote clients. The idea of method caching is to store results of
read-only method invocations with respect to the application server's interface
on the client side. If the client invokes the same method with the same
arguments again, the corresponding result can be taken from the cache without
contacting the server. It has been shown that this approach can considerably
improve a real world system's efficiency.
This paper extends the concept of method caching by addressing the case where
clients wrap related method invocations in ACID transactions. Demarcating
sequences of method calls in this way is supported by many important
application server standards. In this context the paper presents an
architecture, a theory and an efficient protocol for maintaining full
transactional consistency and in particular serializability when using a method
cache on the client side. In order to create a protocol for scheduling cached
method results, the paper extends a classical transaction formalism. Based on
this extension, a recovery protocol and an optimistic serializability protocol
are derived. The latter one differs from traditional transactional cache
protocols in many essential ways. An efficiency experiment validates the
approach: Using the cache a system's performance and scalability are
considerably improved
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