sandbox for API concepts

devdocs/sketches/invokable_models.md

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+# Invokable Operations
+
+The op execution interface between native drivers and NoSQLBench
+drivers needs to be simplified as well as generalized. These are
+generally competing goals, as the simplest interfaces are more often
+the more specific ones.  This poses a few challenges in terms of
+design, particularly because there are a few execution patterns that
+need to be supported:
+
+
+- Runnable
+- Callable
+- Functional
+- Futures/async
+- Driver methods
+
+To clarify the differences, here are some basic examples:
+
+    # runnable
+    op.run()
+    pulsarOp.run(ctx::close);
+
+    # callable
+    R = op.call()
+
+    # functional
+    O = op.apply(I)
+
+    # Futures async
+    Future<R> f= executor.executeAsync(op)
+    R = f.get
+
+    # Driver methods
+    cqlActivity.getSession().executeAsync(statement);
+    dsegraph.getSession().executeGraphAsync(simpleGraphStatement);
+    httpFuture = client.sendAsync(httpOp.request, this.bodyreader);
+    jdbcConn.createStatement().execute(sql)
+    jmxOp.execute();
+    kafkaSequencer.get(cycle).write(cycle);
+    mongoResultDoc = activity.getDatabase().runCommand(queryBson, rms.getReadPreference());
+    WebDriverVerbs.execute(cycle, commandTemplate, context, dryrun);
+
+
+ActivityType<A extends Activity>
+
+