README.dev

High-level:
    This document describes the FlowVisor's internals and is intended for
    people looking to modify/develop the actual code.

    It covers:
    * testing
    * I/O Logic
    * Code layout
    * Thread logic

    A higher-level view of the code is described at:
        https://github.com/OPENNETWORKINGLAB/flowvisor/wiki


====================================

Tests:
    Flowvisor has both JUNIT tests inside the java code
    (./src/tests/....) and regression tests (`make tests`).  At minimum,
    any changes to the code should not break these tests and would
    ideally add their own tests.


I/O LOGIC: 

FlowVisor has two logical structures, a classifier
(org.flowvisor.classifier.FVClassifier.java) and a slicer
(org.flowvisor.slicer.FVSlicer.java).  The classifier is responsible for
figuring out what to do with OF Messages to and from the switch and the
slicer figures out what to do with messages to and from the controller.
Both of them have methods sendMsg() and handleIOEvent().

The handleIOEvent() is triggered when a message is received from a
controller (in FVSlicer) or from the switch (in FVClassifier) *before*
the FlowVisor does its rewriting.  This is the raw message off the wire.

The method sendMsg() is for sending a message to the controller (in
FVSlicer) or to the switch (in FVClassifer) *after* any sort of rewriting
takes place.  The is the post-processed message that is about to be sent
back onto the wire.


CODE LAYOUT:

All of the per-message processing logic is in 
    org.flowvisor.messages.*

    Each message implements the Classifiable and Slicable interfaces.

    Classifiable means that message can be called with 
        classifyFromSwitch(FVClassifier fvClassifier);
    which translates to "the FlowVisor just got this message from a switch: what do I do with it
    and which slice or slice(s) do I sent it to?".

    Slicable means that the message can be called with 
        sliceFromController(FVClassifier fvClassifier, FVSlicer fvSlicer);
    which translates to "the FlowVisor just got this messages from a controller and
    it's going to this switch: what message-level rewriting do I have to do to ensure
    isolation is maintained?".
          


THREAD MODEL:

FlowVisor has very little inter-thread interaction and consequently very
little locking.  Threads send events to each other with the following
logic.

All FVEventHandlers support handleEvent().  This event first looks at
the thread ID of the calling thread and compares it to the thread ID of
the EventHandler.  If they match, the event is processed immediately,
and if not, then the event is queued into the handler's event loop.
There is no shared state between event handlers, only copies of state
and events to update the copies when they become stale.

All of the calls to FVConfig should have synchronization applied to them
on the FVConfig.class object (because the methods and class are static).

INLINE DOCUMENTATION:

Most (all?) of the code is commented with javadoc.  See `make doc`.

RELEASES:
Update the RELEASE-NOTES and then run:
    ./scripts/make-release flowvisor-$version
        - for the make install prompts, enter:
            /usr/local  (default)
            root
            root
            <empty>     (default)
nothing you have done yet is public or permanent; to make it 
    permanent in git, run `git push --tags` and copy the ./scripts/DEB
    tree into place on yuba per the instructions in ./scripts/DEB/README

FYI, the make-release script will, all in one automated swoop:
    1) update the version string in src/org/flowvisor/flowvisor.java
    1.1) makes a new git comment with comment "release flowvisor-$version"
    1.2) runs `git tag flowvisor-$version`
    2) `make tests` and die if error
    3) call ./scripts/make-deb.sh $version
        - builds a debian package for the local architecture
        - dumps the resulting .deb pkg in ./scripts/DEB/unstable/binary-$ARCH