A reverse proxy that only speaks json-rpc 2.0. Upstream routing is done using json-rpc method "namespaces".

A json-rpc method namespace is a json-rpc method prefix joined to the method name with a period, so a method in the "sbds" namespace begins with sbds. and will be forwarded to a sbds endpoint:

POST / HTTP/1.1
Content-Type: application/json

{
  "method": "sbds.count_operations",
  "params": {"operation":"account_creates"},
  "jsonrpc": "2.0",
  "id": 1
}

Any json-rpc method with no period in the method name is presumed to be in the "steemd" namespace and will be forwarded to a steemd endpoint:

POST / HTTP/1.1
Content-Type: application/json

{
  "method": "get_block",
  "params": [1],
  "jsonrpc": "2.0",
  "id": 1
}

1. parse the upstream config and build the routing, caching, timeout data structures
2. open websocket and/or http connections to upstreams
3. initialize memory cache and open connections to redis cache
4. register route and error handlers

1. validate jsonrpc request
2. convert individual jsonrpc requests into JSONRPCRequest objects, which add its pseudo-urn and upstream configuration
3. generate cache key (pseudo-urn for the moment)
4. if a single jsonrpc request:
   1. check in-memory cache, if miss
   2. make a redis get call
5. if a batch call:
   1. check in-memory cache for all keys
   2. for any misses:
   3. make a redis mget request for any keys not found in memory cache
6. if all data loaded from cache:
   1. merge cached data with requests to form response
   2. send response
7. if any jsonrpc call results aren't in cache:
8. determine which upstream url and protocol (websockets or http) to use to fetch them
9. start upsteam request timers
10. fetch missing jsonrpc calls
11. end upstream response timers
12. decide if response is a valid jsonrpc response and that it is not a jsonrpc error response
13. if response is valid, and response is not a jsonrpc error response, determine the cache ttl for that jsonrpc namespace.method
14. for some calls, verify the the response is a consensus response or not, and modify cache ttl for irreversible block responses
15. return single jsonrpc response or assembled jsonrpc responses for batch requests
16. cache response in redis cache
17. cache response in memory