SDN Controller Programming Guide

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This following figure illustrates this:
Figure 14 OpenFlow Controller
Message Library
The Message Library is a Java implementation of the OpenFlow specification, providing facilities
for encoding and decoding OpenFlow messages from and to Java rich data types.
Design Goals
The following are the overall design goals of the library:
 To span all protocol versions
 However, actively supporting just 1.0.0 and 1.3.1
 To be extensible
 Easily accommodating future versions
 To provide an elegant, yet simple, API for dealing with OpenFlow messages
 To reduce the burden on application developers
 Insulating developers from differences across protocol versions, as much as possible
 To expose the semantics but hide the syntax details
 Developers will not be required to encode and decode bitmasks, calculate message
lengths, insert padding, etc.
 To be robust and type-safe
 Working with Java enumerations and types
Design Choices
Some specific design choices were made to establish the underlying principles of the
implementation, to help meet the goals specified above.