Transcript Rudimentary Client-Server Message Board Ricky Landry COP5611

Rudimentary Client-Server
Message Board
Ricky Landry
COP5611 – Operating Systems Design Principles
University of Central Florida
April 16, 2012
Fundamental Requirements
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Ability to create topics
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Ability to create comments associated with a topic
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Ability to produce information on the author of a topic
or comment
Ability to produce the timestamp of creation and last
modification time of a topic or a comment
Ability to remove a topic or comment (only if requested
by the author)
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Critical Design Decisions
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Client-Server Architecture
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Multi-threaded Server
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Stateless
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Messaging Protocol
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Java Swing Client Front-End (GUI)
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Message Board Database
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Server-side database was written specifically for the
application to explore design challenges
Multi-threaded server design required mutually exclusive
access to the database to handle concurrency and
atomicity concerns
Accomplished through the use of object locks built into
the Java language
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synchronized(this){ … } wraps database access calls
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Server Database Design
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Singleton-patterned database consists of:
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List of MbdbTopic objects, stored as a Hashtable
List of MbdbComment objects, stored as a Hashtable
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Server Database Design
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MbdbTopic object consists of:
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topic name
author name
creation time
topic header
deleted state
list of the comment headers of child comments
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Server Database Design
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MbdbComment object consists of:
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comment message
author name
creation time
comment header
deleted state
unique identifier of its parent topic
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Server Database Design
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TopicHeader and CommentHeader Objects contain:
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Topic/Comment unique identifier
Topic/Comment last update time
Definition of TopicHeaderList and CommentHeaderList
containers, respectively
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Server Design
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Used the Java Serialization API for serialized object
transfer between server and client.
Listen socket is a Java ServerSocket object
When a connection is made, the new socket connected
to the client is handed off to a worker thread spawned
specifically for the client
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Server Design
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Protocol Design
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Defines the following aspects of the client-server model:
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Credentials
Topic message data payloads
Comment message data payloads
Message structure
Message types
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Protocol Design
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Client-to-Server Message Types:
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CREATE_TOPIC
CREATE_COMMENT
REMOVE_TOPIC
REMOVE_COMMENT
GET_TOPIC_HEADERS
GET_TOPIC_OBJECT
GET_COMMENT_OBJECT
CREDENTIALS
CLOSING_CONNECTION
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Protocol Design
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Server-to-Client Message Types:
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TOPIC_HEADERS_REPLY
TOPIC_OBJECT_REPLY
COMMENT_OBJECT_REPLY
AUTHETICATION_SUCCESS
AUTHETICATION_FAILURE
INVALID_TOPIC_ID
INVALID_COMMENT_ID
INVALID_REPLY_RECEIVED
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Client Database Design
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The client has its own database that contains the client
state
Has four containers:
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One
One
One
One
containing MbdbTopic objects
containing MbdbComment objects
containing the read state for each topic
containing the read state for each comment
Defines wrappers for Topic/Comment objects and their
respective read state
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Client Database Design
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Client Controller Design
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Responsible for client database management and access
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Updates the client database with server data
Provides current (undeleted) client data to the front-end
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Responsible for communication with the server
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Responsible for managing client credentials
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Client Front-End Design
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Built using the Java Swing API
Provides basic interface to underlying function
Topic Window Mockup
Comment Window Mockup
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Client Front-End Design
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Client Front-End Design
Topic Window
Comment Window
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Questions
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