---
layout: default
---
:source-highlighter: coderay
:icons: font

include::_banner.adoc[]

== Request/Reply (I ask, you answer)

image::../reqrep.png[I ask, you answer]

Request/Reply is used for synchronous communications where each question
is responded with a single answer, for example remote procedure calls (RPCs).
Like <<pipeline#,Pipeline>>, it also can perform load-balancing.  This
is the only reliable messaging pattern in the suite, as it automatically
will retry if a request is not matched with a response.

.reqprep.c
[source,c]
----
include::src/reqrep.c[]
----
<1> Blithely assumes message is ASCIIZ string. Real code should check it.

.Compilation
[source,bash]
----
gcc reqrep.c -lnng -o reqrep
----

.Execution
[source,bash]
----
include::src/reqrep.sh[]
----

.Output
----
include::src/reqrep.out[]
----