Add example of record which supports RPC and a client

Record has x and y-coordinate fields and a timestamp and also provides
a service which sets (x,y) to a sequence of values.

An RPC client application (move) sends positions as an array.

exampleRPC/src/positionClient.cpp

@@ -0,0 +1,126 @@
+/**
+ * Copyright - See the COPYRIGHT that is included with this distribution.
+ * EPICS exampleCPP is distributed subject to a Software License Agreement found
+ * in file LICENSE that is included with this distribution.
+ */
+
+#include <pv/pvData.h>
+#include <pv/rpcService.h>
+#include <pv/clientFactory.h>
+#include <pv/rpcClient.h>
+
+#include <string>
+#include <iostream>
+
+using namespace epics::pvData;
+
+
+static StructureConstPtr makeDeviceStructure()
+{
+    static StructureConstPtr deviceStructure;
+    if (deviceStructure.get() == 0)
+    {
+        FieldCreatePtr fieldCreate = getFieldCreate();
+
+        deviceStructure = fieldCreate->createFieldBuilder()->
+            add("x",pvDouble)->
+            add("y",pvDouble)->
+            createStructure();
+    }
+    return deviceStructure;
+}
+
+
+static StructureConstPtr makeArgumentStructure()
+{
+    static StructureConstPtr requestStructure;
+    if (requestStructure.get() == 0)
+    {
+        FieldCreatePtr fieldCreate = getFieldCreate();
+
+        requestStructure = fieldCreate->createFieldBuilder()->
+            addArray("value", makeDeviceStructure())->
+            createStructure();
+    }
+    return requestStructure;
+}
+
+// Set a pvAccess connection timeout, after which the client gives up trying 
+// to connect to server.
+const static double REQUEST_TIMEOUT = 3.0;
+const static std::string DEVICE_NAME = "mydevice";
+const static std::string APP_NAME = "move";
+
+void usage()
+{
+    std::cout << "Usage: " << APP_NAME << " [x_1 y_1] ... [x_n y_n]\n"
+              << "Sequentially sets the values of the x and y fields of "
+              << DEVICE_NAME << " to (x_i,y_i).\n"
+              << "Returns on completion."
+              << std::endl;
+}
+
+/**
+  */
+int main (int argc, char *argv[])
+{
+    for (int i = 1; i < argc; ++i)
+    {
+        std::string arg(argv[i]);
+        if (arg == "-h" || arg == "--help")
+        {
+            usage();
+            return 0;
+        }
+    } 
+
+    if ((argc % 2) != 1)
+    {
+        std::cerr << APP_NAME << " requires an even number of arguments."
+                  << std::endl;
+        usage();
+        return 1;
+    }
+    // Start the pvAccess client side.
+    epics::pvAccess::ClientFactory::start();
+
+    try
+    {
+        PVStructurePtr arguments(getPVDataCreate()->createPVStructure(makeArgumentStructure()));
+
+        PVStructureArray::svector values;
+
+        for (int i = 1; i < argc; )
+        {
+            PVStructurePtr point(getPVDataCreate()->createPVStructure(makeDeviceStructure()));
+            point->getSubField<PVDouble>("x")->put(atof(argv[i++]));
+            point->getSubField<PVDouble>("y")->put(atof(argv[i++]));
+            values.push_back(point);
+        }
+
+	    arguments->getSubField<PVStructureArray>("value")->replace(freeze(values));
+
+        epics::pvAccess::RPCClient::shared_pointer client
+             = epics::pvAccess::RPCClient::create(DEVICE_NAME);
+
+        PVStructurePtr response = client->request(arguments,
+            REQUEST_TIMEOUT + 1.0 * (argc/2));
+
+        std::cout << "Done" << std::endl;
+    }
+    catch (epics::pvAccess::RPCRequestException & ex)
+    {
+        std::cerr << "Operation failed. RPCException:" << std::endl;
+        std::cerr << ex.what() << std::endl;
+    }
+    catch (...)
+    {
+        // Catch any other exceptions so we always call ClientFactory::stop().
+        std::cerr << "Unexpected exception." << std::endl;
+    }
+
+    // Stop pvAccess client, so that this application exits cleanly.
+    epics::pvAccess::ClientFactory::stop();
+
+    return 0;
+}