Programming model doc update

Documentation/wip/ProgrammingModel.md

@@ -1,21 +1,8 @@
-Programming Model
+# Programming Model
-=================
 
 This document describes the programming model for fission functions.  
 
-See TERMINOLOGY for definitions of terms, such as _function_,
+## Time Limits
-_instance_, and _trigger_.
-
-
-Idempotency
-===========
-
-Fission assumes that functions are idempotent.  Functions whose instances
-die without a result are restarted, upto a certain restart limit.
-
-
-Time Limits
-===========
 
 By default, there is no time limit on fission functions.  
 
@@ -23,49 +10,15 @@ Idle running instances may be killed at any time (usually after the
 default idle timeout of 10 minutes, but this is configurable).
 
 
-Mapping
+## HTTP Triggers
-=======
 
-This section specifies the mapping between: (1) HTTP and other
+Functions triggered over HTTP receive the HTTP request object in the
-triggers, and (2) function parameters, return values, and exceptions.
+context.  The request's query string, POST body, etc. can be retrieved
-
+from this object.  The interface is language-specific: see [TODO] for
-In other words, this section describes how a function should be called
+documentation on the context object in each environment.
-based on a given trigger, and how the functions behaviour affects the
-result returned from the trigger.
-
-The HTTP Trigger
-----------------
-
-NodeJS
-------
-
-NodeJS functions are called with a context object.
-
-context.request contains the nodeJS Request object.
-
-In addition,
-
-context.queryString contains the parsed querystring
-
-context.body contains the parsed body
-
-context.status sets the HTTP response status code.  If context.status
-is an invalid HTTP status, then the HTTP status is set to 500.
-
-Exceptions result in a HTTP 500 error.
 
 
+## Kubernetes Watch Event Triggers
 
-
+Kubernetes watches can be used to trigger functions.  These functions
-
+receive the Kubernetes watch.Event object in JSON-serialized form.
-XXX Should we have a "context.done()"?  What are the pros and cons?
-
-XXX Who handles serialization and deserialization?  Should we do json
-    automatically based on content-type and accept headers?
-
-
-Python
-------
-
-Same as node, pretty much.
-