Floodlight OpenFlow Controller -Project Floodlight
A Big Switch Networks-sponsored community project
Floodlight Is an Open SDN Controller
Why Use Floodlight?
OpenFlow – works with physical- and virtual- switches that speak the OpenFlow protocol
Apache-licensed – lets you use Floodlight for almost any purpose
Open community – Floodlight is developed by an open community of developers. We welcome code contributions from active participants and we’ll openly share information on project status, roadmap, bugs, etc.
Easy to Use- Floodlight is drop dead simple to build and run. Read through the Documentation (link)
Tested and Supported – Floodlight is actively tested and improved by a community of professional developers at floodlight-dev@openflowhub.org.
The Floodlight Open SDN Controller is an enterprise-class, Apache-licensed, Java-based OpenFlow Controller. It is supported by a community of developers including a number of engineers from .
OpenFlow is a open standard managed by Open Networking Foundation.
It specifies a protocol through switch a remote controller can modify the behavior of networking devices through a well-defined “forwarding instruction set”.
Floodlight is designed to work with the growing number of switches, routers, virtual switches, and access points that support the OpenFlow standard.
Feature Highlights
Offers a module loading system that make it simple to extend and enhance.
Easy to set up with minimal dependencies
Supports a broad range of virtual- and physical- OpenFlow switches
Can handle mixed OpenFlow and non-OpenFlow networks – it can manage multiple “islands” of OpenFlow hardware switches
Designed to be high-performance – is multithreaded from the ground up
Support for OpenStack (link) cloud orchestration platformAccessController (Java Platform SE 7 )
JavaScript is disabled on your browser.
Class AccessController
java.security.AccessController
public final class AccessController
The AccessController class is used for access control operations
and decisions.
More specifically, the AccessController class is used for
three purposes:
to decide whether an access to a critical system
resource is to be allowed or denied, based on the security policy
currently in effect,
to mark code as being "privileged", thus affecting subsequent
access determinations, and
to obtain a "snapshot" of the current calling context so
access-control decisions from a different context can be made with
respect to the saved context.
determines whether the access request indicated by a specified
permission should be granted or denied. A sample call appears
below. In this example, checkPermission will determine
whether or not to grant "read" access to the file named "testFile" in
the "/temp" directory.
FilePermission perm = new FilePermission("/temp/testFile", "read");
AccessController.checkPermission(perm);
If a requested access is allowed,
checkPermission returns quietly. If denied, an
AccessControlException is
thrown. AccessControlException can also be thrown if the requested
permission is of an incorrect type or contains an invalid value.
Such information is given whenever possible.
Suppose the current thread traversed m callers, in the order of caller 1
to caller 2 to caller m. Then caller m invoked the
checkPermission method.
The checkPermission method determines whether access
is granted or denied based on the following algorithm:
for (int i = i & 0; i--) {
if (caller i's domain does not have the permission)
throw AccessControlException
else if (caller i is marked as privileged) {
if (a context was specified in the call to doPrivileged)
context.checkPermission(permission)
// Next, check the context inherited when the thread was created.
// Whenever a new thread is created, the AccessControlContext at
// that time is stored and associated with the new thread, as the
// "inherited" context.
inheritedContext.checkPermission(permission);
A caller can be marked as being "privileged"
and below).
When making access control decisions, the checkPermission
method stops checking if it reaches a caller that
was marked as "privileged" via a doPrivileged
call without a context argument (see below for information about a
context argument). If that caller's domain has the
specified permission, no further checking is done and
checkPermission
returns quietly, indicating that the requested access is allowed.
If that domain does not have the specified permission, an exception
is thrown, as usual.
The normal use of the "privileged" feature is as follows. If you
don't need to return a value from within the "privileged" block, do
the following:
somemethod() {
...normal code here...
AccessController.doPrivileged(new PrivilegedAction&Void&() {
public Void run() {
// privileged code goes here, for example:
System.loadLibrary("awt");
// nothing to return
...normal code here...
PrivilegedAction is an interface with a single method, named
The above example shows creation of an implementation
a concrete implementation of the
run method is supplied.
When the call to doPrivileged is made, an
instance of the PrivilegedAction implementation is passed
to it. The doPrivileged method calls the
run method from the PrivilegedAction
implementation after enabling privileges, and returns the
run method's return value as the
doPrivileged return value (which is
ignored in this example).
If you need to return a value, you can do something like the following:
somemethod() {
...normal code here...
String user = AccessController.doPrivileged(
new PrivilegedAction&String&() {
public String run() {
return System.getProperty("user.name");
...normal code here...
If the action performed in your run method could
throw a "checked" exception (those listed in the throws clause
of a method), then you need to use the
PrivilegedExceptionAction interface instead of the
PrivilegedAction interface:
somemethod() throws FileNotFoundException {
...normal code here...
FileInputStream fis = AccessController.doPrivileged(
new PrivilegedExceptionAction&FileInputStream&() {
public FileInputStream run() throws FileNotFoundException {
return new FileInputStream("someFile");
} catch (PrivilegedActionException e) {
// e.getException() should be an instance of FileNotFoundException,
// as only "checked" exceptions will be "wrapped" in a
// PrivilegedActionException.
throw (FileNotFoundException) e.getException();
...normal code here...
Be *very* careful in your use of the "privileged" construct, and
always remember to make the privileged code section as small as possible.
Note that checkPermission always performs security checks
within the context of the currently executing thread.
Sometimes a security check that should be made within a given context
will actually need to be done from within a
different context (for example, from within a worker thread).
method and
AccessControlContext class are provided
for this situation. The getContext method takes a "snapshot"
of the current calling context, and places
it in an AccessControlContext object, which it returns. A sample call is
the following:
AccessControlContext acc = AccessController.getContext()
AccessControlContext itself has a checkPermission method
that makes access decisions based on the context it encapsulates,
rather than that of the current execution thread.
Code within a different context can thus call that method on the
previously-saved AccessControlContext object. A sample call is the
following:
acc.checkPermission(permission)
There are also times where you don't know a priori which permissions
to check the context against. In these cases you can use the
doPrivileged method that takes a context:
somemethod() {
AccessController.doPrivileged(new PrivilegedAction&Object&() {
public Object run() {
// Code goes here. Any permission checks within this
// run method will require that the intersection of the
// callers protection domain and the snapshot's
// context have the desired permission.
...normal code here...
Method Summary
Modifier and Type
Method and Description
static void
Determines whether the access request indicated by the
specified permission should be allowed or denied, based on
the current AccessControlContext and security policy.
static &T&&T
(&T&&action)
Performs the specified PrivilegedAction with privileges
static &T&&T
(&T&&action,
Performs the specified PrivilegedAction with privileges
enabled and restricted by the specified
AccessControlContext.
static &T&&T
(&T&&action)
Performs the specified PrivilegedExceptionAction with
privileges enabled.
static &T&&T
(&T&&action,
Performs the specified PrivilegedExceptionAction with
privileges enabled and restricted by the specified
AccessControlContext.
static &T&&T
(&T&&action)
Performs the specified PrivilegedAction with privileges
static &T&&T
(&T&&action)
Performs the specified PrivilegedExceptionAction with
privileges enabled.
This method takes a "snapshot" of the current calling context, which
includes the current Thread's inherited AccessControlContext,
and places it in an AccessControlContext object.
Methods inherited from class&java.lang.
, , , , , , , , , ,
Method Detail
doPrivileged
public static&&T&&T&doPrivileged(&T&&action)
Performs the specified PrivilegedAction with privileges
enabled. The action is performed with all of the permissions
possessed by the caller's protection domain.
If the action's run method throws an (unchecked)
exception, it will propagate through this method.
Note that any DomainCombiner associated with the current
AccessControlContext will be ignored while the action is performed.
Parameters:action - the action to be performed.
Returns:the value returned by the action's run method.
- if the action is nullSee Also:,
doPrivilegedWithCombiner
public static&&T&&T&doPrivilegedWithCombiner(&T&&action)
Performs the specified PrivilegedAction with privileges
enabled. The action is performed with all of the permissions
possessed by the caller's protection domain.
If the action's run method throws an (unchecked)
exception, it will propagate through this method.
This method preserves the current AccessControlContext's
DomainCombiner (which may be null) while the action is performed.
Parameters:action - the action to be performed.
Returns:the value returned by the action's run method.
- if the action is nullSince:
See Also:,
doPrivileged
public static&&T&&T&doPrivileged(&T&&action,
Performs the specified PrivilegedAction with privileges
enabled and restricted by the specified
AccessControlContext.
The action is performed with the intersection of the permissions
possessed by the caller's protection domain, and those possessed
by the domains represented by the specified
AccessControlContext.
If the action's run method throws an (unchecked) exception,
it will propagate through this method.
Parameters:action - the action to be performed.context - an access control context
representing the restriction to be applied to the
caller's domain's privileges before performing
the specified action.
If the context is
then no additional restriction is applied.
Returns:the value returned by the action's run method.
- if the action is nullSee Also:,
doPrivileged
public static&&T&&T&doPrivileged(&T&&action)
Performs the specified PrivilegedExceptionAction with
privileges enabled.
The action is performed with all of the
permissions possessed by the caller's protection domain.
If the action's run method throws an unchecked
exception, it will propagate through this method.
Note that any DomainCombiner associated with the current
AccessControlContext will be ignored while the action is performed.
Parameters:action - the action to be performed
Returns:the value returned by the action's run method
- if the specified action's
run method threw a checked exception
- if the action is nullSee Also:,
doPrivilegedWithCombiner
public static&&T&&T&doPrivilegedWithCombiner(&T&&action)
Performs the specified PrivilegedExceptionAction with
privileges enabled.
The action is performed with all of the
permissions possessed by the caller's protection domain.
If the action's run method throws an unchecked
exception, it will propagate through this method.
This method preserves the current AccessControlContext's
DomainCombiner (which may be null) while the action is performed.
Parameters:action - the action to be performed.
Returns:the value returned by the action's run method
- if the specified action's
run method threw a checked exception
- if the action is nullSince:
See Also:,
doPrivileged
public static&&T&&T&doPrivileged(&T&&action,
Performs the specified PrivilegedExceptionAction with
privileges enabled and restricted by the specified
AccessControlContext.
The action is performed with the
intersection of the permissions possessed by the caller's
protection domain, and those possessed by the domains represented by the
specified AccessControlContext.
If the action's run method throws an unchecked
exception, it will propagate through this method.
Parameters:action - the action to be performedcontext - an access control context
representing the restriction to be applied to the
caller's domain's privileges before performing
the specified action.
If the context is
then no additional restriction is applied.
Returns:the value returned by the action's run method
- if the specified action's
run method
threw a checked exception
- if the action is nullSee Also:,
getContext
public static&&getContext()
This method takes a "snapshot" of the current calling context, which
includes the current Thread's inherited AccessControlContext,
and places it in an AccessControlContext object. This context may then
be checked at a later point, possibly in another thread.
Returns:the AccessControlContext based on the current context.See Also:
checkPermission
public static&void&checkPermission(&perm)
Determines whether the access request indicated by the
specified permission should be allowed or denied, based on
the current AccessControlContext and security policy.
This method quietly returns if the access request
is permitted, or throws an AccessControlException otherwise. The
getPermission method of the AccessControlException returns the
perm Permission object instance.
Parameters:perm - the requested permission.
- if the specified permission
is not permitted, based on the current security policy.
- if the specified permission
is null and is checked based on the
security policy currently in effect.
For further API reference and developer documentation, see . That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
© , Oracle and/or its affiliates.
All rights reserved. Use is subject to . Also see the .
Scripting on this page tracks web page traffic, but does not change the content in any way.}