Bellovin, Jason Nieh Email privacy is of crucial importance. Existing email encryption approaches are comprehensive but seldom used due to their complexity and inconvenience. We take a new approach to simplify email encryption and improve its usability by implementing receiver-controlled encryption: To avoid the problem of users having to move a single private key between devices, we implement per-device key pairs:
API This chapter explains the classes available in JGroups that will be used by applications to build reliable group communication applications. The focus is on creating and using channels.
Information in this document may not be up-to-date, but the nature of the classes in JGroups described here is the same. All of the classes discussed here are in the org. Utility classes The org.
Util class contains useful common functionality which cannot be assigned to any other package.
The byte array is then returned. This method is often used to serialize objects into the byte buffer of a message. The second method returns a reconstructed object from a buffer. Both methods throw an exception if the object cannot be serialized or unserialized.
The second method takes an input stream and reads an object from it. Interfaces These interfaces are used with some of the APIs presented below, therefore they are listed first.
MessageListener The MessageListener interface below provides callbacks for message reception and for providing and setting the state: The getState and setState methods are used to fetch and set the group state e. Refer to State transfer for a discussion of state transfer.
The suspect callback is invoked by JGroups whenever a member if suspected of having crashed, but not yet excluded [ 1 ]. The block method is called to notify the member that it will soon be blocked sending messages.
This is done by the FLUSH protocol, for example to ensure that nobody is sending messages while a state transfer or view installation is in progress. When block returns, any thread sending messages will be blocked, until FLUSH unblocks the thread again, e.
Therefore, block can be used to send pending messages or complete some other work. The unblock method is called to notify the member that the FLUSH protocol has completed and the member can resume sending messages.
If the member did not stop sending messages on blockFLUSH simply blocked them and will resume, so no action is required from a member. Implementation of the unblock callback is optional.
Note that it is oftentimes simpler to extend ReceiverAdapter see below and implement the needed callbacks than to implement all methods of both of these interfaces, as most callbacks are not needed. Receiver public interface Receiver extends MessageListener, MembershipListener; A Receiver can be used to receive messages and view changes; receive will be invoked as soon as a message has been received, and viewAccepted will be called whenever a new view is installed.
ReceiverAdapter This class implements Receiver with no-op implementations. When implementing a callback, we can simply extend ReceiverAdapter and overwrite receive in order to not having to implement all callbacks of the interface.
ReceiverAdapter looks as follows: Note that anything that could block should not be done in a callback. This includes sending of messages; if we have FLUSH on the stack, and send a message in a viewAccepted callback, then the following happens: However, because installation of the view triggers the viewAccepted callback, sending of messages inside of viewAccepted will block.
This in turn blocks the viewAccepted thread, so the flush will never return! If we need to send a message in a callback, the sending should be done on a separate thread, or a timer task should be submitted to the timer. Whenever a channel is closed, disconnected or opened, the corresponding callback will be invoked.
Address Each member of a group has an address, which uniquely identifies the member. The interface for such an address is Address, which requires concrete implementations to provide methods such as comparison and sorting of addresses.
JGroups addresses have to implement the following interface: Please never use implementations of Address directly; Address should always be used as an opaque identifier of a cluster node! Actual implementations of addresses are often generated by the bottommost protocol layer e.
This allows for all possible sorts of addresses to be used with JGroups. Since an address uniquely identifies a channel, and therefore a group member, it can be used to send messages to that group member, e.
The default implementation of Address is org. It uniquely identifies a node, and when disconnecting and reconnecting to a cluster, a node is given a new UUID on reconnection. UUIDs are never shown directly, but are usually shown as a logical name see Logical names.
This is a name given to a node either via the user or via JGroups, and its sole purpose is to make logging output a bit more readable.The CPUID opcode is a processor supplementary instruction (its name derived from CPU IDentification) for the x86 architecture allowing software to discover details of the processor.
It was introduced by Intel in when it introduced the Pentium and SL-enhanced processors.. By using the CPUID opcode, software can determine processor type and the presence of features (like MMX/SSE). L3 caches are almost always shared amongst cores; L2 and L1 might also be shared.
- L1 Level 1 (L1) cache is the primary cache – often accessed in . View and Download Dell Force10 C configuration manual online. FTOS Configuration Guide FTOS E-Series TeraScale, C-Series, S-Series (S50/S25).
Force10 C Server pdf manual download. I understand that the processor brings data into the cache via cache lines, which - for instance, on my Atom processor - brings in about 64 bytes at a time, whatever the size of the actual data being read.
A CPU cache is a hardware cache used by the central processing unit (CPU) of a computer to reduce the average cost (time or energy) to access data from the main memory. A cache is a smaller, faster memory, closer to a processor core, which stores copies of the data from frequently used main memory locations.
Cache Level 3 Unit 1 b Unit 1-B Explain why it is important that practitioners understand the limits and boundaries of their role when working with children. The Role of level 3.