Introduction to WSO2 ESB Pass-Through Transport

WSO2 ESB PASS-THROUGH TRANSPORT

By Chanaka Fernando

WHAT IS PASS-THROUGH TRANSPORT (PTT)?

The non-blocking HTTP transport of WSO2 ESB which makes the world’s fastest open source ESB

WHY PTT FOR ESB?

!

Ultra-fast, low latency mediation of HTTP requests.

Supporting a very large number of inbound (client-ESB) and outbound (ESB-server) connections concurrently (we were looking at several thousand concurrent connections).

Automatic throttling and graceful performance degradation in the presence of slow or faulty clients and servers.

WHY NOT NHTTP?

Use dual-buffer model

Message getting build for every request

Overhead of moving data from one buffer to other

HOW PTT DO IT?

use single shared buffer

content aware message processing

CONTENT-AWARENESS

content-unaware mediators (eg: drop, send)

content-aware mediators (eg: xslt)

conditionally content-aware mediators (eg: log)

axiom engaged only necessary

PARSING MESSAGES

If content-aware then engage axiom

use second buffer when message is built

when rampart engaged, special handler checks before parsing

HIGH LEVEL ARCHITECTURE

HIGH LEVEL ARCHITECTURE

Client request comes through Http-Core towards SourceHandler

Produces data to the pipe (through decoder) and TargetHandler consumes data

If content-aware, create a secondary buffer and TargetHandler consumes data from that buffer

STATE MACHINE OF PTT

Request

Response

STATE MACHINE OF PTT

message is divided into HEADER and BODY

when client connects goes to REQUEST_READY

start receiving data, reads the header and goes to REQUEST_HEAD

reads the message body and goes to REQUEST_BODY

when finishes reading, goes to REQUEST_DONE

WHERE IS PTT?

REFERENCES

http://techfeast-hiranya.blogspot.com/2013/02/how-worlds-fastest-esb-was-made.html

http://shafreenanfar.blogspot.com/2014/02/wso2-esb-passthrough-transport-basics.html