diff --git a/src/commands/Command.cpp b/src/commands/Command.cpp
index e203dc542..4345d9d42 100644
--- a/src/commands/Command.cpp
+++ b/src/commands/Command.cpp
@@ -68,6 +68,12 @@ Command& Command::operator= (const Command& other)
   return *this;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool Command::read_only () const
+{
+  return false;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 bool Command::operator== (const Command& other) const
 {
diff --git a/src/commands/Command.h b/src/commands/Command.h
index c8247dfb4..d45a6f255 100644
--- a/src/commands/Command.h
+++ b/src/commands/Command.h
@@ -36,12 +36,13 @@ public:
   Command (const Command&);
   Command& operator= (const Command&);
   bool operator== (const Command&) const;     // TODO Is this necessary?
-  ~Command ();
+  virtual ~Command ();
 
   static Command* factory (const std::string&);
 
-  bool implements (const std::string&) const;
-  std::string execute (const std::string&);
+  virtual bool read_only () const;
+  virtual bool implements (const std::string&) const = 0;
+  virtual std::string execute (const std::string&) = 0;
 
 private:
 };
diff --git a/src/commands/Install.cpp b/src/commands/Install.cpp
index 2f8717acf..d99ea85db 100644
--- a/src/commands/Install.cpp
+++ b/src/commands/Install.cpp
@@ -33,6 +33,9 @@ extern Context context;
 
 ////////////////////////////////////////////////////////////////////////////////
 Install::Install ()
+/*
+: _name ("")
+*/
 {
 }
 
@@ -77,12 +80,23 @@ Install::~Install ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool Install::implements (const std::string&) const
+bool Install::read_only () const
 {
   return false;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+bool Install::implements (const std::string& command_line) const
+{
+  return false;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Algorithm:
+//   Copy file rc.data.location/extensions
+//   Generate UUID
+//   Call the "install" function once, store results in rc:
+//     extension.<uuid>=<JSON>
 std::string Install::execute (const std::string&)
 {
   return "output";
diff --git a/src/commands/Install.h b/src/commands/Install.h
index 19739539f..c440b7942 100644
--- a/src/commands/Install.h
+++ b/src/commands/Install.h
@@ -39,6 +39,7 @@ public:
   bool operator== (const Install&) const;     // TODO Is this necessary?
   ~Install ();
 
+  bool read_only () const;
   bool implements (const std::string&) const;
   std::string execute (const std::string&);