From 0b6dcde04302bbe0364a22933fb0de1e4a046799 Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Tue, 18 Aug 2020 13:00:44 -0700
Subject: [PATCH] add example RPC server/client

---
 example/Makefile       |  6 +++
 example/client.cpp     |  2 +
 example/mailbox.cpp    |  2 +-
 example/rpc_client.cpp | 49 +++++++++++++++++++++++
 example/rpc_server.cpp | 91 ++++++++++++++++++++++++++++++++++++++++++
 example/spam.cpp       |  2 +-
 example/ticker.cpp     |  2 +-
 7 files changed, 151 insertions(+), 3 deletions(-)
 create mode 100644 example/rpc_client.cpp
 create mode 100644 example/rpc_server.cpp

diff --git a/example/Makefile b/example/Makefile
index 9fa2e74..0b418f1 100644
--- a/example/Makefile
+++ b/example/Makefile
@@ -23,6 +23,12 @@ ticker_SRCS += ticker.cpp
 TESTPROD_HOST += client
 client_SRCS += client.cpp
 
+TESTPROD_HOST += rpc_server
+rpc_server_SRCS += rpc_server.cpp
+
+TESTPROD_HOST += rpc_client
+rpc_client_SRCS += rpc_client.cpp
+
 #===========================
 
 include $(TOP)/configure/RULES
diff --git a/example/client.cpp b/example/client.cpp
index 391fdd3..3949820 100644
--- a/example/client.cpp
+++ b/example/client.cpp
@@ -109,4 +109,6 @@ int main(int argc, char* argv[])
 
         std::cout<<"Result is:\n"<<result<<std::endl;
     }
+
+    return 0;
 }
diff --git a/example/mailbox.cpp b/example/mailbox.cpp
index 6f38eb1..93bb85b 100644
--- a/example/mailbox.cpp
+++ b/example/mailbox.cpp
@@ -83,7 +83,7 @@ int main(int argc, char* argv[])
     // Associate a data type (and maybe initial value) with this PV
     pv.open(initial);
 
-    // Build server which will server this PV
+    // Build server which will serve this PV
     // Configure using process environment.
     server::Server serv = server::Config::fromEnv()
             .build()
diff --git a/example/rpc_client.cpp b/example/rpc_client.cpp
new file mode 100644
index 0000000..650a113
--- /dev/null
+++ b/example/rpc_client.cpp
@@ -0,0 +1,49 @@
+/**
+ * Copyright - See the COPYRIGHT that is included with this distribution.
+ * pvxs is distributed subject to a Software License Agreement found
+ * in file LICENSE that is included with this distribution.
+ */
+/**
+ * Run in conjunction with the rpc_server example
+ *
+ *   ./rpc_server mypv
+ *
+ * Then in another shell run:
+ *
+ *   ./rpc_client mypv 1 2
+ */
+
+#include <iostream>
+
+#include <pvxs/client.h>
+#include <pvxs/log.h>
+
+using namespace pvxs;
+
+int main(int argc, char* argv[])
+{
+    if(argc<4) {
+        std::cerr<<"Usage: "<<argv[0]<<" <pvname> <lhs> <rhs>\n";
+        return 1;
+    }
+
+    // Read $PVXS_LOG from process environment and update
+    // logging configuration.  eg.
+    //    export PVXS_LOG=*=DEBUG
+    // makes a lot of noise.
+    logger_config_env();
+
+    // Create a client context
+    client::Context ctxt(client::Config::fromEnv()
+                         .build());
+
+    auto reply(ctxt.rpc(argv[1])
+                   .arg("lhs", argv[2])
+                   .arg("rhs", argv[3])
+                   .exec()
+                   ->wait(5.0));
+
+    std::cout<<"Reply\n"<<reply;
+
+    return 0;
+}
diff --git a/example/rpc_server.cpp b/example/rpc_server.cpp
new file mode 100644
index 0000000..79a58d9
--- /dev/null
+++ b/example/rpc_server.cpp
@@ -0,0 +1,91 @@
+/**
+ * Copyright - See the COPYRIGHT that is included with this distribution.
+ * pvxs is distributed subject to a Software License Agreement found
+ * in file LICENSE that is included with this distribution.
+ */
+/**
+ * Serves a single PV name.
+ * Only implements an RPC operation which adds two numbers.
+ *
+ *   ./rpc_server mypv
+ *
+ * Then in another shell run:
+ *
+ *   pvxcall mypv lhs=1 rhs=2
+ */
+
+#include <iostream>
+
+#include <epicsTime.h>
+
+#include <pvxs/sharedpv.h>
+#include <pvxs/server.h>
+#include <pvxs/nt.h>
+#include <pvxs/log.h>
+
+using namespace pvxs;
+
+int main(int argc, char* argv[])
+{
+    if(argc<=1) {
+        std::cerr<<"Usage: "<<argv[0]<<" <pvname>\n";
+        return 1;
+    }
+
+    // Read $PVXS_LOG from process environment and update
+    // logging configuration.  eg.
+    //    export PVXS_LOG=*=DEBUG
+    // makes a lot of noise.
+    logger_config_env();
+
+    // Actually creating the PV.
+    // buildReadonly() installs a default onPut() handler which
+    // rejects all Put operations.
+    server::SharedPV pv(server::SharedPV::buildReadonly());
+
+    // Provide an RPC handler
+    pv.onRPC([](server::SharedPV& pv,
+                std::unique_ptr<server::ExecOp>&& op,
+                Value&& top)
+    {
+        // Callback
+
+        // assume arguments encoded NTURI
+        auto rhs = top["query.rhs"].as<double>();
+        auto lhs = top["query.lhs"].as<double>();
+
+        auto reply(nt::NTScalar{TypeCode::Float64}.create());
+        reply["value"] = lhs + rhs;
+
+        op->reply(reply);
+        // Scale-able applications may reply outside of this callback,
+        // and from another thread.
+    });
+
+    // (Optional) Provide a data type for the PV.
+    // Provides a hint to users that Get, Put, or Monitor is not
+    // meaningful for this PV
+    Value initial = nt::NTScalar{TypeCode::String}.create();
+    initial["value"] = "RPC only";
+    pv.open(initial);
+
+    // Build server which will serve this PV
+    // Configure using process environment.
+    server::Server serv = server::Config::fromEnv()
+            .build()
+            .addPV(argv[1], pv);
+
+    // (optional) Print the configuration this server is using
+    // with any auto-address list expanded.
+    std::cout<<"Effective config\n"<<serv.config();
+
+    std::cout<<"Running\n";
+
+    // Start server and run forever, or until Ctrl+c is pressed.
+    // Returns on SIGINT or SIGTERM
+    serv.run();
+
+    std::cout<<"Done\n";
+
+    return 0;
+}
diff --git a/example/spam.cpp b/example/spam.cpp
index 7a483b8..976674d 100644
--- a/example/spam.cpp
+++ b/example/spam.cpp
@@ -100,7 +100,7 @@ int main(int argc, char* argv[])
     auto src = std::make_shared<SpamSource>();
     src->names->insert(argv[1]);
 
-    // Build server which will server this PV
+    // Build server which will serve this PV
     // Configure using process environment.
     server::Server serv = server::Config::fromEnv()
             .build()
diff --git a/example/ticker.cpp b/example/ticker.cpp
index 3b8f40a..1dd6c17 100644
--- a/example/ticker.cpp
+++ b/example/ticker.cpp
@@ -70,7 +70,7 @@ int main(int argc, char* argv[])
     // Associate a data type (and maybe initial value) with this PV
     pv.open(initial);
 
-    // Build server which will server this PV
+    // Build server which will serve this PV
     // Configure using process environment.
     server::Server serv = server::Config::fromEnv()
             .build()