Transcript System Design

System Design
for
Home Automaton
Design Goals
• Performance Criteria
– Server prioritizes client requests to provide
quick response time to critical requests.
• E.g. Device state changes supersede image
transfers.
– Client is multi-threaded to allow simultaneous
server communication and user interaction.
Server is a single-threaded state machine.
– One zone will be held in memory at any given
time to limit memory consumption.
Design Goals
• Dependability Criteria
– Errors in server connection will be reported to
the user.
– Requests are given an encrypted identifier.
Server reports success or failure to client with
identifier.
– Out-of-order transmissions generate errors
and the connection is terminated to handle
packet spoofing.
Design Goals
• Cost Criteria
– Open-source; free for all. Yee-Ha!
• Maintenance/Extendability Criteria
– Extendable to multiple device types.
– Server will be able to communicate with a
client on any platform.
• End User Criteria
– Easy point-and-click user interface.
System Decomposition
Hardware/Software Mapping
• Client
– C#, Open GL
• Server
– C++
• Protocol
– TCP/IP Sockets
Persistent Data Management
• Zones will be stored in data files managed
by data structures.
• Users will be stored in a data file on the
server
• Server configuration will also be stored in
a data file
Access Control
• There are two types of users:
Administrator and Occupant.
• Administrator has full access to all
features of the client and server.
• Occupant has access only to change
device states.
• Both user types are authenticated with a
username and password.
Software Control
• The server will operate on a proceduredriven state machine with a singlethreaded loop handling all input/output and
device control operations.
• The client will operate on an event-driven
model with multiple threads (GUI &
Network)
Boundary Conditions
• Establish Server Connection
– User is authenticated. All devices (real and
virtual) and the image file for the root zone are
downloaded to the client
• Disconnect From Server
– Server request queue is flushed and
executed, while errors are reported to the
client.
Boundary Conditions
• Connection Unexpectedly Terminated
– Server processes all requests in its queue and
stores errors in a log file.
– Client reports an error to the user and offers
to reconnect. Upon reconnection, Client will
be updated with the current devices states.