async RPC service and example

testApp/remote/rpcServiceAsyncExample.cpp

@@ -0,0 +1,87 @@
+/**
+ * Copyright - See the COPYRIGHT that is included with this distribution.
+ * pvAccessCPP is distributed subject to a Software License Agreement found
+ * in file LICENSE that is included with this distribution.
+ */
+
+#include <pv/pvData.h>
+#include <pv/rpcServer.h>
+
+using namespace epics::pvData;
+using namespace epics::pvAccess;
+
+static Structure::const_shared_pointer resultStructure =
+        getFieldCreate()->createFieldBuilder()->
+               add("c", pvDouble)->
+               createStructure();
+
+// s1 starts with s2 check
+static bool starts_with(const std::string& s1, const std::string& s2) {
+    return s2.size() <= s1.size() && s1.compare(0, s2.size(), s2) == 0;
+}
+
+class SumServiceImpl :
+    public RPCServiceAsync
+{
+   void request(PVStructure::shared_pointer const & pvArguments,
+                RPCResponseCallback::shared_pointer const & callback)
+    {
+        // NTURI support
+        PVStructure::shared_pointer args(
+                    (starts_with(pvArguments->getStructure()->getID(), "epics:nt/NTURI:1.")) ?
+                        pvArguments->getStructureField("query") :
+                        pvArguments
+                        );
+
+        // get fields and check their existence
+        PVScalar::shared_pointer af = args->getSubField<PVScalar>("a");
+        PVScalar::shared_pointer bf = args->getSubField<PVScalar>("b");
+        if (!af || !bf)
+        {
+            callback->requestDone(
+                        Status(
+                            Status::STATUSTYPE_ERROR,
+                            "scalar 'a' and 'b' fields are required"
+                            ),
+                        PVStructure::shared_pointer());
+            return;
+        }
+
+        // get the numbers (and convert if neccessary)
+        double a, b;
+        try
+        {
+            a = af->getAs<double>();
+            b = bf->getAs<double>();
+        }
+        catch (std::exception &e)
+        {
+            callback->requestDone(
+                        Status(
+                            Status::STATUSTYPE_ERROR,
+                            std::string("failed to convert arguments to double: ") + e.what()
+                            ),
+                        PVStructure::shared_pointer());
+            return;
+        }
+        
+        // create return structure and set data
+        PVStructure::shared_pointer result = getPVDataCreate()->createPVStructure(resultStructure);
+        result->getSubField<PVDouble>("c")->put(a+b);
+
+        callback->requestDone(Status::Ok, result);
+    }
+};
+
+int main()
+{
+    RPCServer server;
+
+    server.registerService("sum", RPCServiceAsync::shared_pointer(new SumServiceImpl()));
+    // you can register as many services as you want here ...
+
+    server.printInfo();
+    server.run();
+
+    return 0;
+}