Erlang and OTP in Action.pdf - Synrc

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perform the same function. However, they are not processes themselves. JInterface allows
you, the Java programmer, to manage threads in any way that you would like. Therefore
gives you direct access to this mailbox abstraction so that your threads can interact with
nodes as they will.
We create the mailbox by asking an OtpNode object to create a mailbox for us. We have
two kinds of mailboxes that can be created, one with a name and one without. If we create a
mailbox with a name that name is registered in the exact same way a registered process is.
That is we can send messages to the mailbox using a registered name just like any other
registered process. If we create the mbox without a name then it acts like any other
anonymous process and we need the PID to interact with it. Yes, JInterface mailboxes also
have a PID like any other Erlang process. Let’s look at how these are actually created in the
next snippet.
OtpMbox mbox = node.createMbox(“our_registered_name”);
To create an mbox without a registered name we just do the same without actually passing
in the name to our node.
OtpMbox mbox = node.createMbox();
Once we have the mailbox we can use it to send and receive messages. The two
fundamental APIs we are going to use to do this are the send and receive methods of the
OtpMbox class. There are several variations of these methods, but I will leave it to you to
take a look at the javadocs for the variations. Sending and receiving data requires that we
marshal the data to and from the native Erlang format. Fortunately, for us JInterface gives
us the tools we need to be able to do that.
Mapping Erlang Data structures Onto Java
Anything we send to or receive from an Erlang node or anything masquerading as an
Erlang node needs to be marshaled to and from the native Erlang types. We do this by using
the type mapping classes that JInterface provides for us. These classes are a direct
representation of the Erlang types in Java.
Table 13.1 Erlang Java Mappings
Erlang Type
Atom
Java Class
OtpErlangAtom
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