new exception to catch situation where invalid IS server name is given

asyncmsg/NameService.h

@@ -25,6 +25,14 @@ namespace daq {
                            ERS_EMPTY, 
                            ERS_EMPTY)
 
+    ERS_DECLARE_ISSUE_BASE(asyncmsg,
+		           InvalidISServer,
+			   Issue,
+			   "Cannot publish because of invalid IS server: " << m_server,
+			   ERS_EMPTY,
+			   ((std::string)m_server)
+                           )
+
     ERS_DECLARE_ISSUE_BASE(asyncmsg,
                            CannotResolve,
                            Issue,

src/NameService.cxx

@@ -109,9 +109,16 @@ namespace daq {
             ISInfoDictionary d(m_partition);
 
             ISServerIterator servers(m_partition, m_is_server + ".*");
+            if(servers.entries() == 0) {
+                throw InvalidISServer(ERS_HERE,m_is_server);
+            }
             while(servers++) {
                 // may throw
-                d.checkin(std::string(servers.name()) + ".MSG_" + name, info);
+                try {
+                   d.checkin(std::string(servers.name()) + ".MSG_" + name, info);
+                } catch(ers::Issue& reason) {
+                   throw InvalidISServer(ERS_HERE, servers.name(), reason);
+                }
             }
 
         }