java.lang.Object
- org.jgroups.stack.Protocol

All Implemented Interfaces:

Lifecycle

Direct Known Subclasses:

AUTH, BARRIER, BATCH, BATCH2, CLEAR_FLAGS, COMPRESS, COUNTER, DAISYCHAIN, DELAY, DETECT_LOOPBACKS, DISCARD, DISCARD_PAYLOAD, Discovery, DROP, DUPL, Encrypt, EXAMPLE, FailureDetection, FD_HOST, FD_SOCK, FD_SOCK2, FlowControl, FORK, ForkProtocol, Fragmentation, GMS, HDRS, INJECT_VIEW, KeyExchange, MAKE_BATCH, MERGE3, MessageDispatcher.ProtocolAdapter, NAKACK2, NON_BLOCKING_SENDS, PDC, PERF, ProtocolStack, RATE, RATE_LIMITER, RATE_LIMITER2, RED, RELAY, ReliableMulticast, ReliableUnicast, REVERSE, REVERSE2, RSVP, SEQUENCER, SEQUENCER2, SERIALIZE, SHUFFLE, SIZE, SNIFF, SOS, STABLE, STATE_TRANSFER, STATS, STOMP, StreamingStateTransfer, THREAD_COUNT, TIME, TP, TRACE, UNBATCH, UNICAST3, VERIFY_SUSPECT, VERIFY_SUSPECT2
```
public abstract class Protocol
extends java.lang.Object
implements Lifecycle
```
The Protocol class provides a set of common services for protocol layers. Each layer has to be a subclass of Protocol and override a number of methods (typically just up(), down() and getName(). Layers are stacked in a certain order to form a protocol stack. Events are passed from lower layers to upper ones and vice versa. E.g. a Message received by the UDP layer at the bottom will be passed to its higher layer as an Event. That layer will in turn pass the Event to its layer and so on, until a layer handles the Message and sends a response or discards it, the former resulting in another Event being passed down the stack.
The important thing to bear in mind is that Events have to be passed on between layers in FIFO order which is guaranteed by the Protocol implementation and must be guaranteed by subclasses implementing their on Event queuing.
Note that each class implementing interface Protocol MUST provide an empty, public constructor !

Author:

Bela Ban

Field Summary

Fields
Modifier and Type	Field	Description
`protected java.lang.String`	`after_creation_hook`
`protected Protocol`	`down_prot`
`protected boolean`	`ergonomics`
`protected short`	`id`
`protected Address`	`local_addr`
`protected Log`	`log`
`protected java.util.List<Policy>`	`policies`
`protected ProtocolStack`	`stack`
`protected boolean`	`stats`
`protected Protocol`	`up_prot`

Constructor Summary

Constructors
Constructor Description

Protocol()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected boolean`	`accept(Message msg)`	Called by the default implementation of `up(org.jgroups.util.MessageBatch)` for each message to determine if the message should be removed from the message batch (and handled by the current protocol) or not.
`<T extends Protocol> T`	`addPolicy(Policy p)`
`Address`	`addr()`
`<T extends Protocol> T`	`addr(Address addr)`
`java.lang.String`	`afterCreationHook()`
`void`	`destroy()`	This method is called on a `JChannel.close()`.
`java.lang.Object`	`down(Event evt)`	An event is to be sent down the stack.
`java.lang.Object`	`down(Message msg)`	A message is sent down the stack.
`java.util.concurrent.CompletableFuture<java.lang.Object>`	`down(Message msg, boolean async)`	Passes a message down asynchronously.
`void`	`enableStats(boolean flag)`
`Address`	`getAddress()`
`java.util.List<java.lang.Object>`	`getComponents()`	After configuring the protocol itself from the properties defined in the XML config, a protocol might have additional component objects which need to be configured.
`<T extends Protocol> T`	`getDownProtocol()`
`java.util.List<java.lang.Integer>`	`getDownServices()`	Returns all services provided by protocols below the current protocol
`short`	`getId()`
`short[]`	`getIdsAbove()`	Returns the protocol IDs of all protocols above this one (excluding the current protocol)
`java.lang.String`	`getLevel()`
`Log`	`getLog()`
`java.lang.String`	`getName()`
`java.util.List<? extends Policy>`	`getPolicies()`
`ProtocolStack`	`getProtocolStack()`
`SocketFactory`	`getSocketFactory()`	Returns the SocketFactory associated with this protocol, if overridden in a subclass, or passes the call down
`ThreadFactory`	`getThreadFactory()`	Supposed to be overwritten by subclasses.
`TP`	`getTransport()`
`<T extends Protocol> T`	`getUpProtocol()`
`java.util.List<java.lang.Integer>`	`getUpServices()`	Returns all services provided by the protocols above the current protocol
`java.lang.Object`	`getValue(java.lang.String name)`
`void`	`init()`	Called after a protocol has been created and before the protocol is started.
`boolean`	`isErgonomics()`
`<T extends Protocol> T`	`level(java.lang.String level)`
`void`	`parse(XmlNode node)`	Called by the XML parser when subelements are found in the configuration of a protocol.
`java.lang.String`	`policies()`
`java.util.List<java.lang.Integer>`	`providedDownServices()`	List of events that are provided to layers below (they will be handled when sent from down below)
`java.util.List<java.lang.Integer>`	`providedUpServices()`	List of events that are provided to layers above (they will be handled when sent down from above)
`<T extends Protocol> T`	`removePolicy(Policy p)`
`java.util.List<java.lang.Integer>`	`requiredDownServices()`	List of events that are required to be answered by some layer below
`java.util.List<java.lang.Integer>`	`requiredUpServices()`	List of events that are required to be answered by some layer above
`void`	`resetStatistics()`
`void`	`resetStats()`
`<T extends Protocol> T`	`setAddress(Address addr)`
`<T extends Protocol> T`	`setDownProtocol(Protocol prot)`
`<T extends Protocol> T`	`setErgonomics(boolean ergonomics)`
`<T extends Protocol> T`	`setId(short id)`
`<T extends Protocol> T`	`setLevel(java.lang.String level)`	Sets the level of a logger.
`<T extends Protocol> T`	`setPolicies(java.util.List<Policy> l)`
`<T extends Protocol> T`	`setProtocolStack(ProtocolStack s)`
`void`	`setSocketFactory(SocketFactory factory)`	Sets a SocketFactory.
`<T extends Protocol> T`	`setUpProtocol(Protocol prot)`
`<T extends Protocol> T`	`setValue(java.lang.String name, java.lang.Object value)`
`void`	`start()`	This method is called on a `JChannel.connect(String)`; starts work.
`boolean`	`statsEnabled()`
`void`	`stop()`	Called on a `JChannel.disconnect()`; stops work (e.g.
`java.lang.String`	`toString()`
`java.lang.Object`	`up(Event evt)`	An event was received from the protocol below.
`java.lang.Object`	`up(Message msg)`	A single message was received.
`void`	`up(MessageBatch batch)`	Sends up a multiple messages in a `MessageBatch`.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - up_prot
```
protected Protocol up_prot
```
  - down_prot
```
protected Protocol down_prot
```
  - stack
```
protected ProtocolStack stack
```
  - stats
```
protected boolean stats
```
  - ergonomics
```
protected boolean ergonomics
```
  - after_creation_hook
```
protected java.lang.String after_creation_hook
```
  - id
```
protected short id
```
  - local_addr
```
protected Address local_addr
```
  - log
```
protected final Log log
```
  - policies
```
protected java.util.List<Policy> policies
```
- Constructor Detail
  - Protocol
```
public Protocol()
```
- Method Detail
  - setLevel
```
public <T extends Protocol> T setLevel(java.lang.String level)
```
    Sets the level of a logger. This method is used to dynamically change the logging level of a running system, e.g. via JMX. The appender of a level needs to exist.
    
    Parameters:
    
    level - The new level. Valid values are "fatal", "error", "warn", "info", "debug", "trace" (capitalization not relevant)
  - getLevel
```
public java.lang.String getLevel()
```
  - level
```
public <T extends Protocol> T level(java.lang.String level)
```
  - getAddress
```
public Address getAddress()
```
  - addr
```
public Address addr()
```
  - addr
```
public <T extends Protocol> T addr(Address addr)
```
  - setAddress
```
public <T extends Protocol> T setAddress(Address addr)
```
  - isErgonomics
```
public boolean isErgonomics()
```
  - setErgonomics
```
public <T extends Protocol> T setErgonomics(boolean ergonomics)
```
  - getProtocolStack
```
public ProtocolStack getProtocolStack()
```
  - statsEnabled
```
public boolean statsEnabled()
```
  - enableStats
```
public void enableStats(boolean flag)
```
  - getName
```
public java.lang.String getName()
```
  - getId
```
public short getId()
```
  - setId
```
public <T extends Protocol> T setId(short id)
```
  - getUpProtocol
```
public <T extends Protocol> T getUpProtocol()
```
  - getDownProtocol
```
public <T extends Protocol> T getDownProtocol()
```
  - setUpProtocol
```
public <T extends Protocol> T setUpProtocol(Protocol prot)
```
  - setDownProtocol
```
public <T extends Protocol> T setDownProtocol(Protocol prot)
```
  - setProtocolStack
```
public <T extends Protocol> T setProtocolStack(ProtocolStack s)
```
  - afterCreationHook
```
public java.lang.String afterCreationHook()
```
  - getLog
```
public Log getLog()
```
  - getPolicies
```
public java.util.List<? extends Policy> getPolicies()
```
  - policies
```
public java.lang.String policies()
```
  - setPolicies
```
public <T extends Protocol> T setPolicies(java.util.List<Policy> l)
```
  - addPolicy
```
public <T extends Protocol> T addPolicy(Policy p)
```
  - removePolicy
```
public <T extends Protocol> T removePolicy(Policy p)
```
  - getValue
```
public java.lang.Object getValue(java.lang.String name)
```
  - setValue
```
public <T extends Protocol> T setValue(java.lang.String name,
                                       java.lang.Object value)
```
  - getComponents
```
public java.util.List<java.lang.Object> getComponents()
```
    After configuring the protocol itself from the properties defined in the XML config, a protocol might have additional component objects which need to be configured. This callback allows a protocol developer to configure those other objects. This call is guaranteed to be invoked after the protocol itself has been configured.
    See AUTH for an example.
  - parse
```
public void parse(XmlNode node)
           throws java.lang.Exception
```
    Called by the XML parser when subelements are found in the configuration of a protocol. This allows a protocol to define protocol-specific information and to parse it
    
    Throws:
    
    java.lang.Exception
  - getIdsAbove
```
public short[] getIdsAbove()
```
    Returns the protocol IDs of all protocols above this one (excluding the current protocol)
  - getTransport
```
public TP getTransport()
```
  - getThreadFactory
```
public ThreadFactory getThreadFactory()
```
    Supposed to be overwritten by subclasses. Usually the transport returns a valid non-null thread factory, but thread factories can also be created by individual protocols
    
    Returns:
  - getSocketFactory
```
public SocketFactory getSocketFactory()
```
    Returns the SocketFactory associated with this protocol, if overridden in a subclass, or passes the call down
    
    Returns:
    
    SocketFactory
  - setSocketFactory
```
public void setSocketFactory(SocketFactory factory)
```
    Sets a SocketFactory. Socket factories are typically provided by the transport (TP)
    
    Parameters:
    
    factory -
  - resetStatistics
```
public void resetStatistics()
```
  - resetStats
```
public void resetStats()
```
  - init
```
public void init()
          throws java.lang.Exception
```
    Called after a protocol has been created and before the protocol is started. Attributes are already set. Other protocols are not yet connected and events cannot yet be sent.
    
    Specified by:
    
    init in interface Lifecycle
    
    Throws:
    
    java.lang.Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the the channel constructor will throw an exception
  - start
```
public void start()
           throws java.lang.Exception
```
    This method is called on a JChannel.connect(String); starts work. Protocols are connected ready to receive events. Will be called from bottom to top.
    
    Specified by:
    
    start in interface Lifecycle
    
    Throws:
    
    java.lang.Exception - Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, so JChannel.connect(String) will throw an exception
  - stop
```
public void stop()
```
    Called on a JChannel.disconnect(); stops work (e.g. by closing multicast socket). Will be called from top to bottom.
    
    Specified by:
    
    stop in interface Lifecycle
  - destroy
```
public void destroy()
```
    This method is called on a JChannel.close(). Does some cleanup; after the call, the VM will terminate
    
    Specified by:
    
    destroy in interface Lifecycle
  - requiredUpServices
```
public java.util.List<java.lang.Integer> requiredUpServices()
```
    List of events that are required to be answered by some layer above
  - requiredDownServices
```
public java.util.List<java.lang.Integer> requiredDownServices()
```
    List of events that are required to be answered by some layer below
  - providedUpServices
```
public java.util.List<java.lang.Integer> providedUpServices()
```
    List of events that are provided to layers above (they will be handled when sent down from above)
  - providedDownServices
```
public java.util.List<java.lang.Integer> providedDownServices()
```
    List of events that are provided to layers below (they will be handled when sent from down below)
  - getDownServices
```
public final java.util.List<java.lang.Integer> getDownServices()
```
    Returns all services provided by protocols below the current protocol
  - getUpServices
```
public final java.util.List<java.lang.Integer> getUpServices()
```
    Returns all services provided by the protocols above the current protocol
  - down
```
public java.lang.Object down(Event evt)
```
    An event is to be sent down the stack. A protocol may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the protocol may need to add a header to it (or do nothing at all) before sending it down the stack using down_prot.down().
  - down
```
public java.lang.Object down(Message msg)
```
    A message is sent down the stack. Protocols may examine the message and do something (e.g. add a header) with it, before passing it down.
    
    Since:
    
    4.0
  - down
```
public java.util.concurrent.CompletableFuture<java.lang.Object> down(Message msg,
                                                                     boolean async)
```
    Passes a message down asynchronously. The sending is executed in the transport's thread pool. If the pool is full and the message is marked as Message.TransientFlag.DONT_BLOCK, then it will be dropped, otherwise it will be sent on the caller's thread.
    
    Parameters:
    
    msg - The message to be sent
    
    async - Whether to send the message asynchronously
    
    Returns:
    
    A CompletableFuture of the result (or exception)
  - up
```
public java.lang.Object up(Event evt)
```
    An event was received from the protocol below. Usually the current protocol will want to examine the event type and - depending on its type - perform some computation (e.g. removing headers from a MSG event type, or updating the internal membership list when receiving a VIEW_CHANGE event). Finally, the event is either a) discarded, or b) an event is sent down the stack using down_prot.down() or c) the event (or another event) is sent up the stack using up_prot.up().
  - up
```
public java.lang.Object up(Message msg)
```
    A single message was received. Protocols may examine the message and do something (e.g. add a header) with it before passing it up.
    
    Since:
    
    4.0
  - up
```
public void up(MessageBatch batch)
```
    Sends up a multiple messages in a MessageBatch. The sender of the batch is always the same, and so is the destination (null == multicast messages). Messages in a batch can be OOB messages, regular messages, or mixed messages, although the transport itself will create initial MessageBatches that contain only either OOB or regular messages.
    The default processing below sends messages up the stack individually, based on a matching criteria (calling accept(Message)), and - if true - calls up(org.jgroups.Event) for that message and removes the message. If the batch is not empty, it is passed up, or else it is dropped.
    Subclasses should check if there are any messages destined for them (e.g. using MessageBatch.iterator(Predicate)), then possibly remove and process them and finally pass the batch up to the next protocol. Protocols can also modify messages in place, e.g. ENCRYPT could decrypt all encrypted messages in the batch, not remove them, and pass the batch up when done.
    
    Parameters:
    
    batch - The message batch
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - accept
```
protected boolean accept(Message msg)
```
    Called by the default implementation of up(org.jgroups.util.MessageBatch) for each message to determine if the message should be removed from the message batch (and handled by the current protocol) or not.
    
    Parameters:
    
    msg - The message. Guaranteed to be non-null
    
    Returns:
    
    True if the message should be handled by this protocol (will be removed from the batch), false if the message should remain in the batch and be passed up.
    The default implementation tries to find a header matching the current protocol's ID and returns true if there is a match, or false otherwise

Class Protocol

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

up_prot

down_prot

stack

stats

ergonomics

after_creation_hook

id

local_addr

log

policies

Constructor Detail

Protocol

Method Detail

setLevel

getLevel

level

getAddress

addr

addr

setAddress

isErgonomics

setErgonomics

getProtocolStack

statsEnabled

enableStats

getName

getId

setId

getUpProtocol

getDownProtocol

setUpProtocol

setDownProtocol

setProtocolStack

afterCreationHook

getLog

getPolicies

policies

setPolicies

addPolicy

removePolicy

getValue

setValue

getComponents

parse

getIdsAbove

getTransport

getThreadFactory

getSocketFactory

setSocketFactory

resetStatistics

resetStats

init

start

stop

destroy

requiredUpServices

requiredDownServices

providedUpServices

providedDownServices

getDownServices

getUpServices

down

down

down

up

up

up

toString

accept