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java.lang.Object | +--com.ericsson.otp.erlang.AbstractNode | +--com.ericsson.otp.erlang.OtpLocalNode | +--com.ericsson.otp.erlang.OtpNode
Represents a local OTP node. This class is used when you do not wish to manage connections yourself - outgoing connections are established as needed, and incoming connections accepted automatically. This class supports the use of a mailbox API for communication, while management of the underlying communication mechanism is automatic and hidden from the application programmer.
Once an instance of this class has been created, obtain one or more mailboxes in order to send or receive messages. The first message sent to a given node will cause a connection to be set up to that node. Any messages received will be delivered to the appropriate mailboxes.
To shut down the node, call close()
. This will
prevent the node from accepting additional connections and it will
cause all existing connections to be closed. Any unread messages in
existing mailboxes can still be read, however no new messages will
be delivered to the mailboxes.
Note that the use of this class requires that Epmd (Erlang Port Mapper Daemon) is running on each cooperating host. This class does not start Epmd automatically as Erlang does, you must start it manually or through some other means. See the Erlang documentation for more information about this.
Inner Class Summary | |
class |
OtpNode.Acceptor
|
class |
OtpNode.Mailboxes
|
Fields inherited from class com.ericsson.otp.erlang.OtpLocalNode |
epmd,
port |
Constructor Summary | |
OtpNode(java.lang.String node)
Create a node using the default cookie. |
|
OtpNode(java.lang.String node,
java.lang.String cookie)
Create a node. |
|
OtpNode(java.lang.String node,
java.lang.String cookie,
int port)
Create a node. |
Method Summary | |
void |
close()
Close the node. |
void |
closeMbox(OtpMbox mbox)
Close the specified mailbox. |
OtpMbox |
createMbox()
Create an unnamed mailbox that can be used to
send and receive messages with other, similar mailboxes and with
Erlang processes. |
OtpMbox |
createMbox(java.lang.String name)
Create an named mailbox that can be used to send and receive messages with other, similar mailboxes and with Erlang processes. |
protected void |
finalize()
|
java.lang.String[] |
getNames()
Get a list of all known registered names on this node. |
boolean |
ping(java.lang.String node,
long timeout)
Determine if another node is alive. |
boolean |
registerName(java.lang.String name,
OtpMbox mbox)
Register or remove a name for the given mailbox. |
void |
registerStatusHandler(OtpNodeStatus handler)
Register interest in certain system events. |
OtpErlangPid |
whereis(java.lang.String name)
Determine the pid corresponding to a
registered name on this node. |
Methods inherited from class com.ericsson.otp.erlang.OtpLocalNode |
createPid,
createPort,
createRef,
getEpmd,
port,
setEpmd |
Methods inherited from class com.ericsson.otp.erlang.AbstractNode |
alive,
cookie,
host,
node,
setCookie,
toString |
Methods inherited from class java.lang.Object |
clone,
equals,
getClass,
hashCode,
notify,
notifyAll,
wait,
wait,
wait |
Constructor Detail |
public OtpNode(java.lang.String node) throws java.io.IOException
Create a node using the default cookie. The default cookie is found by reading the first line of the .erlang.cookie file in the user's home directory. The home directory is obtained from the System property "user.home".
If the file does not exist, an empty string is used. This method makes no attempt to create the file.
node
- the name of this node.public OtpNode(java.lang.String node, java.lang.String cookie) throws java.io.IOException
node
- the name of this node.cookie
- the authorization cookie that will be used by this
node when it communicates with other nodes.public OtpNode(java.lang.String node, java.lang.String cookie, int port) throws java.io.IOException
node
- the name of this node.cookie
- the authorization cookie that will be used by this
node when it communicates with other nodes.port
- the port number you wish to use for incoming
connections. Specifying 0 lets the system choose an available
port.Method Detail |
public void close()
protected void finalize()
public OtpMbox createMbox()
mailbox
that can be used to
send and receive messages with other, similar mailboxes and with
Erlang processes. Messages can be sent to this mailbox by using
its associated pid
.public void closeMbox(OtpMbox mbox)
the
- mailbox to close.
After this operation, the mailbox will no longer be able to receive messages. Any delivered but as yet unretrieved messages can still be retrieved however.
If there are links from the mailbox to other pids
, they will be broken when this method is
called and exit signals will be sent.
public OtpMbox createMbox(java.lang.String name)
pid
.name
- a name to register for this mailbox. The name must be
unique within this OtpNode.public boolean registerName(java.lang.String name, OtpMbox mbox)
Register or remove a name for the given mailbox. Registering
a name for a mailbox enables others to send messages without
knowing the pid
of the mailbox. A mailbox
can have at most one name; if the mailbox already had a name,
calling this method will supercede that name.
name
- the name to register for the mailbox. Specify null to
unregister the existing name from this mailbox.mbox
- the mailbox to associate with the name.public java.lang.String[] getNames()
public OtpErlangPid whereis(java.lang.String name)
pid
corresponding to a
registered name on this node.pid
corresponding to the
registered name, or null if the name is not known on this node.public void registerStatusHandler(OtpNodeStatus handler)
OtpNodeStatus
handler object contains callback
methods, that will be called when certain events occur.handler
- the callback object to register. To clear the
handler, specify null as the handler to use.public boolean ping(java.lang.String node, long timeout)
Determine if another node is alive. This method has the side effect of setting up a connection to the remote node (if possible). Only a single outgoing message is sent; the timeout is how long to wait for a response.
Only a single attempt is made to connect to the remote node, so for example it is not possible to specify an extremely long timeout and expect to be notified when the node eventually comes up. If you wish to wait for a remote node to be started, the following construction may be useful:
// ping every 2 seconds until positive response while (!me.ping(him,2000));
node
- the name of the node to ping.timeout
- the time, in milliseconds, to wait for response
before returning false.
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