some more interface improvements

serviceinterface/ServiceInterfaceStream.h

@@ -3,11 +3,9 @@
 
 #include <framework/serviceinterface/ServiceInterfaceBuffer.h>
 #include <iostream>
-#include <iosfwd>
-#include <sstream>
 #include <cstdio>
 
-// Unfortunately, there must be a forward declaration of log_fe
+// Unfortunately, there must be a forward declaration of the log front end
 // (MUST be defined in main), to let the system know where to write to.
 namespace sif {
 extern std::ostream debug;
@@ -18,13 +16,32 @@ extern std::ostream error;
 
 
 class ServiceInterfaceStream :
-        public std::basic_ostream<char, std::char_traits<char>> {
+        public std::ostream {
 protected:
     ServiceInterfaceBuffer buf;
 public:
-    ServiceInterfaceStream( std::string set_message,
-    		bool addCrToPreamble = false, uint16_t port = 1234);
+    /**
+     * This constructor is used by specifying the preamble message.
+     * Optionally, the output can be directed to stderr and a CR character
+     * can be prepended to the preamble.
+     * @param set_message
+     * @param errStream
+     * @param addCrToPreamble
+     * @param port
+     */
+    ServiceInterfaceStream(std::string setMessage,
+    		bool errStream = false, bool addCrToPreamble = false,
+			uint16_t port = 1234);
+
+    //! An inactive stream will not print anything.
 	void setActive( bool );
+
+	/**
+	 * This can be used to retrieve the preamble in case it should be printed in
+	 * the unbuffered mode.
+	 * @return Preamle consisting of log message and timestamp.
+	 */
+	std::string getPreamble();
 };