pulper

Lightweight HTTP "kinda" Proxy via AMQP protocol

Requirements

• Node.JS
• Some AMQP server (tested only with RabbitMQ, but theoretically can work with others)

Installation

git clone https://github.com/maprox/pulper.git
cd pulper
npm install

Run

node .

In this case you will run serviceA on port 3000.

There are some environment variables which you can modify if you want:

• MODE [serviceA] - which service you want to run (serviceA, serviceB or serviceC)

• PORT [3000] - which port your service will listen (only for serviceA)

• CALLBACK_URL - url to which serviceC should send the answer from original destination. If empty, service looks for X-CALLBACK-URL header of the request message. (only for serviceC)

• AMQP_EXCHANGE [proxy] - exchange name in AMQP server. All messages will be published to this exchange.

• AMQP_CONNECTION [amqp://guest:[email protected]//] - AMQP connection string

Examples:

1. Run serviceA on port 8080

    PORT=8080 node .
   

2. Run serviceB with different amqp settings

    MODE=serviceB AMQP_CONNECTION=amqp://admin:XsE390@rabbitmq// node .
   

3. Run serviceC with different CALLBACK_URL and CALLBACK_METHOD

    MODE=serviceC CALLBACK_URL=http://localhost:2909/?id=%uid% node .
   

Description

There are three separate services which can be run:

serviceA

This service listens for incoming http connections on some port. When there is an HTTP request, it wraps it in a special internal message and publish to the AMQP exchange (serviceB is the goal here). After that it sends an HTTP response to the client with status code 200 OK and a unique identifier of the internal message (e.g. c5359605-ec5b-4cae-ac52-1c1a7fe5c2c1)

Http request should include several specific headers:

• X-URL - REQUIRED. Destination url (since the host in given HTTP request is wrong and equals to serviceA host). When serviceB receives this message from the AMQP broker it will use this url to send given HTTP request to the addressee.

• X-CALLBACK-URL - OPTIONAL. Where to send response which will be taken from the destination. If this url contains %uid% in it, it will be automatically replaced with unique identifier of the internal message which was returned on the first step.

serviceB

This service connects to the AMQP broker and waits for internal message from serviceA with HTTP request to come.

After it receives this internal message it obtains HTTP request with its destination URL and makes HTTP request to that URL with the same method, headers and body.

After destination endpoint answers something, serviceB wraps its answer into internal message and send it to the AMQP exchange (serviceC is the goal here).

serviceC

Final place of our journey.

This service connects to the AMQP broker and waits for internal message from serviceB with HTTP response to come.

After it receives this internal message with its X-CALLBACK-URL (uses CALLBACK-URL option if this header is empty) it obtains HTTP response and makes HTTP request to that URL with the same status code, headers and body as original HTTP response had.

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