Update readme.md

readme.md

@@ -13,4 +13,68 @@ The stellar components are:
 - **Active Queue Management** is queue management algorithm libraries that schedule packets by buffering, forwarding, marking, or dropping. A plugin creates a queue instance and enqueues packets as its needs. 
   - Question: Who consumes the dequeue events?
 
-![stellar-high-level-design](./docs/imgs/stellar-high-level-design.svg)
+![stellar-high-level-design](./docs/imgs/stellar-high-level-design.svg)
+
+## Packet IO Library
+```
+struct packet
+{
+  enum io_type type;
+  void *raw_pkt;  
+}
+packet_io_loop()
+{
+  packet_io_rx(&rx_pkt)
+  //ingress processing: Tunnel decoding, IP defragmentation
+  session_manager();
+  plugin_manager();
+  //egress processing: AMQ
+  rl_group_id=pkt_get_group_id(rx_pkt);
+  void *raw_pkt=pkt_get_raw(rx_pkt);
+  AMQ_enqueue(group_id[], raw_pkt, pkt_sz);
+
+}
+```
+
+## Plugin Manager
+
+Plugin Management APIs
+```
+pm_session_dettach_me(pm, session);
+pm_session_dettach_others(pm, session);
+```
+## Session Manager
+Session Management APIs
+```
+session_drop_current_packet(session);
+session_set_ratelimit_group(session, rl_group_id);
+session_set_metadata(session, const char *key, void *value, size_t val_sz, free_callback);
+session_get_metadata(session, const char *key, void **value, size_t *val_sz);
+session_del_metadata(session, key)
+session_lock(session, plug_id);
+session_unlock(session, plug_id);
+
+```
+Plugin Example
+```
+plugin_entry(session, pme)
+{
+  session_get_metadata(session, "fw_action", value);
+  if(value==INTERCEPT)
+  {
+    //pm_session_dettach_me(session);
+    return;
+  }
+  ret=check_security_policy(session);
+  if(ret==INTERCEPT)
+  {
+    pm_session_dettach_others(session);
+  }
+  else if(ret==RATE_LIMIT)
+  {
+    group_id=security_policy_id;
+    amq_group_create(group_id, CIR, CBS);
+    session_set_ratelimit_group(session, group_id);
+  }
+}
+```