readme updates

README.md

@@ -5,13 +5,15 @@ Fission is a fast serverless framework for Kubernetes with a focus on
 developer productivity and high performance.
 
 Fission operates on _just code_: Docker and Kubernetes are abstracted
-away.
+away under normal operation, though you can use both to extend Fission
+if you want to.
 
-Fission is extensible to any language.  It currently supports NodeJS
-and Python, with more languages coming soon.
+Fission is extensible to any language; the core is written in Go,
+language-specific parts are isolated in something called
+_environments_ (more below).  Fission currently supports NodeJS and
+Python, with more languages coming soon.
 
-100msec cold start
-------------------
+### Performance: 100msec cold start
 
 Fission maintains a pool of "warm" containers that each contain a
 small dynamic loader.  When a function is first called,
@@ -19,32 +21,50 @@ i.e. "cold-started", a running container is chosen and the function is
 loaded.  This pool is what makes Fission fast: cold-start latencies
 are typically about 100msec.
 
-
-Kubernetes is the right place for Serverless
---------------------------------------------
+### Kubernetes is the right place for Serverless
 
 We're built on Kubernetes because we think any non-trivial app will
 use a combination of serverless functions and more conventional
 microservices, and Kubernetes is a great framework to bring these
 together seamlessly.
 
-
-
 Fission Concepts
-================
+----------------
 
-A _function_ is a piece of code with an entry point.
+A _function_ is a piece of code that follows the fission function
+interface.
 
-An _environment_ is a container with a webserver and dynamic loader
-for functions.  Today, Fission comes with NodeJS and Python
-environments.  You can also add your own: for example, if you want to
-add a binary to your Python image, you can edit the Python
-environment's Dockerfile, rebuild it, and add your new environment to
-Fission.
+An _environment_ contains the language- and runtime-specific parts of
+running a function.  Fission comes with NodeJS and Python
+environments; you can also extend environments or create entirely new
+ones if you want.  (An environment is essentially just a container
+with a webserver and dynamic loader.)
 
 A _trigger_ is something that maps an event to a function; Fission
-supports HTTP triggers today, with upcoming support for other types of
-event triggers.
+supports HTTP routes as triggers today, with upcoming support for
+other types of event triggers, such as timers and Kubernetes events.
+
+Fission 101
+-----------
+
+```bash
+
+  # Add the stock NodeJS env to your Fission deployment
+  $ fission env create --name nodejs --image fission/node-env
+
+  # A one-liner that prints "hello world"
+  $ echo 'module.exports = function(context, callback) { callback(200, "Hello, world!\n"); }' > hello.js  
+
+  # Upload your function code to fission
+  $ fission function create --name hello --env nodejs --code hello.js
+
+  # Map GET /hello to your new function
+  $ fission route create --method GET --url /hello --function hello
+
+  # Run the function.  This takes about 100msec the first time.
+  $ curl http://$FISSION_ROUTER/hello
+  Hello, world!
+```
 
 
 Running Fission on your Cluster