Guble Messaging Server

Guble is a simple user-facing messaging and data replication server written in Go.

Overview

Guble is in an early state (release 0.4). It is already working well and is very useful, but the protocol, API and storage formats may still change (until reaching 0.7). If you intend to use guble, please get in contact with us.

The goal of guble is to be a simple and fast message bus for user interaction and replication of data between multiple devices:

Very easy consumption of messages with web and mobile clients
Fast realtime messaging, as well as playback of messages from a persistent commit log
Reliable and scalable over multiple nodes
User-aware semantics to easily support messaging scenarios between people using multiple devices
Batteries included: usable as front-facing server, without the need of a proxy layer
Self-contained: no mandatory dependencies to other services

Working Features (0.4)

Publishing and subscription of messages to topics and subtopics
Persistent message store with transparent live and offline fetching
WebSocket and REST APIs for message publishing
Commandline client and Go client library
Firebase Cloud Messaging (FCM) adapter: delivery of messages as FCM push notifications
Docker images for server and client
Simple Authentication and Access-Management
Clean shutdown
Improved logging using logrus and logstash formatter
Health-Check with Endpoint
Collection of Basic Metrics, with Endpoint
Added Postgresql as KV Backend
Load testing with 5000 messages per instance
Support for Apple Push Notification services (a new connector alongside Firebase)
Upgrade, cleanup, abstraction, documentation, and test coverage of the Firebase connector
GET list of subscribers / list of topics per subscriber (userID , deviceID)
Support for SMS-sending using Nexmo (a new connector alongside Firebase)

Throughput

Measured on an old notebook with i5-2520M, dual core and SSD. Message payload was 'Hello Word'. Load driver and server were set up on the same machine, so 50% of the cpu was allocated to the load driver.

End-2-End: Delivery of ~35.000 persistent messages per second
Fetching: Receive of ~70.000 persistent messages per second

During the tests, the memory consumption of the server was around ~25 MB.

Roadmap
Guble Docker Image
- Start the Guble Server
- Connecting with the Guble Client
Build and Run
- Build and Start the Server
  - Configuration
- Run All Tests
Clients
Protocol Reference

Roadmap

This is the current (and fast changing) roadmap and todo list:

Roadmap Release 0.5

Replication across multiple servers (in a Guble cluster)
Acknowledgement of message delivery for connectors
Storing the sequence-Id of topics in KV store, if we turn off persistence
Filtering of messages in guble server (e.g. sent by the REST client) according to URL parameters: UserID, DeviceID, Connector name
Updating README to show subscribe/unsubscribe/get/posting, health/metrics

Roadmap Release 0.6

Make notification messages optional by client configuration
Correct behaviour of receive command with maxCount on subtopics
Cancel of fetch in the message store and multiple concurrent fetch commands for the same topic
Configuration of different persistence strategies for topics
Delivery semantics: user must read on one device / deliver only to one device / notify if not connected, etc.
User-specific persistent subscriptions across all clients of the user
Client: (re-)setup of subscriptions after client reconnect
Message size limit configurable by the client with fetching by URL

Roadmap Release 0.7

HTTPS support in the service
Minimal example: chat application
Stable JavaScript client: https://github.com/smancke/guble-js
(TBD) Improved authentication and access-management
(TBD) Add Consul as KV Backend
(TBD) Index-based search of messages using GoLucene

Guble Docker Image

We are providing Docker images of the server and client for your convenience.

Start the Guble Server

There is an automated Docker build for the master at the Docker Hub. To start the server with Docker simply type:

docker run -p 8080:8080 smancke/guble

To see available configuration options:

docker run smancke/guble --help

All options can be supplied on the commandline or by a corresponding environment variable with the prefix GUBLE_. So to let guble be more verbose, you can either use:

docker run smancke/guble --log=info

docker run -e GUBLE_LOG=info smancke/guble

The Docker image has a volume mount point at /var/lib/guble, so if you want to bind-mount the persistent storage from your host you should use:

docker run -p 8080:8080 -v /host/storage/path:/var/lib/guble smancke/guble

Connecting with the Guble Client

The Docker image includes the guble commandline client guble-cli. You can execute it within a running guble container and connect to the server:

docker run -d --name guble smancke/guble
docker exec -it guble /usr/local/bin/guble-cli

Visit the guble-cli documentation for more details.

Build and Run

Since Go makes it very easy to build from source, you can compile guble using a single command. A prerequisite is having an installed Go environment and an empty directory:

sudo apt-get install golang
mkdir guble && cd guble
export GOPATH=`pwd`

Build and Start the Server

Build and start guble with the following commands (assuming that directory /var/lib/guble is already created with read-write rights for the current user):

go get github.com/smancke/guble
bin/guble --log=info

Configuration

CLI Option	Env Variable	Values	Default	Description
`--env`	GUBLE_ENV	development \| integration \| preproduction \| production	development	Name of the environment on which the application is running. Used mainly for logging
`--health-endpoint`	GUBLE_HEALTH_ENDPOINT	resource/path/to/healthendpoint	/admin/healthcheck	The health endpoint to be used by the HTTP server.Can be disabled by setting the value to ""
`--http`	GUBLE_HTTP_LISTEN	format: [host]:port		The address to for the HTTP server to listen on
`--kvs`	GUBLE_KVS	memory \| file \| postgres	file	The storage backend for the key-value store to use
`--log`	GUBLE_LOG	panic \| fatal \| error \| warn \| info \| debug	error	The log level in which the process logs
`--metrics-endpoint`	GUBLE_METRICS_ENDPOINT	resource/path/to/metricsendpoint	/admin/metrics	The metrics endpoint to be used by the HTTP server.Can be disabled by setting the value to ""
`--ms`	GUBLE_MS	memory \| file	file	The message storage backend
`--profile`	GUBLE_PROFILE	cpu \| mem \| block		The profiler to be used
`--storage-path`	GUBLE_STORAGE_PATH	path/to/storage	/var/lib/guble	The path for storing messages and key-value data like subscriptions if defined.The path must exists!

APNS

CLI Option	Env Variable	Values	Default	Description
`--apns`	GUBLE_APNS	true \| false	false	Enable the APNS module in general as well as the connector to the development endpoint
`--apns-production`	GUBLE_APNS_PRODUCTION	true \| false	false	Enables the connector to the apns production endpoint, requires the apns option to be set
`--apns-cert-file`	GUBLE_APNS_CERT_FILE	path/to/cert/file		The APNS certificate file name, use this as an alternative to the certificate bytes option
`--apns-cert-bytes`	GUBLE_APNS_CERT_BYTES	cert-bytes-as-hex-string		The APNS certificate bytes, use this as an alternative to the certificate file option
`--apns-cert-password`	GUBLE_APNS_CERT_PASSWORD	password		The APNS certificate password
`--apns-app-topic`	GUBLE_APNS_APP_TOPIC	topic		The APNS topic (as used by the mobile application)
`--apns-prefix`	GUBLE_APNS_PREFIX	prefix	/apns/	The APNS prefix / endpoint
`--apns-workers`	GUBLE_APNS_WORKERS	number of workers	Number of CPUs	The number of workers handling traffic with APNS (default: number of CPUs)

SMS

CLI Option	Env Variable	Values	Default	Description
`sms`	GUBLE_SMS	true \| false	false	Enable the SMS gateway
`sms_api_key`	GUBLE_SMS_API_KEY	api key		The Nexmo API Key for Sending sms
`sms_api_secret`	GUBLE_SMS_API_SECRET	api secret		The Nexmo API Secret for Sending sms
`sms_topic`	GUBLE_SMS_TOPIC	topic	/sms	The topic for sms route
`sms_workers`	GUBLE_SMS_WORKERS	number of workers	Number of CPUs	The number of workers handling traffic with Nexmo sms endpoint

FCM

CLI Option	Env Variable	Values	Default	Description
`--fcm	GUBLE_FCM`	true \| false	false	Enable the Google Firebase Cloud Messaging connector
`--fcm-api-key`	GUBLE_FCM_API_KEY	api key		The Google API Key for Google Firebase Cloud Messaging
`--fcm-workers`	GUBLE_FCM_WORKERS	number of workers	Number of CPUs	The number of workers handling traffic with Firebase Cloud Messaging
`--fcm-endpoint`	GUBLE_FCM_ENDPOINT	format: url-schema	https://fcm.googleapis.com/fcm/send	The Google Firebase Cloud Messaging endpoint
`--fcm-prefix`	GUBLE_FCM_PREFIX	prefix	/fcm/	The FCM prefix / endpoint

Postgres

CLI Option	Env Variable	Values	Default	Description
`--pg-host`	GUBLE_PG_HOST	hostname	localhost	The PostgreSQL hostname
`--pg-port`	GUBLE_PG_PORT	port	5432	The PostgreSQL port
`--pg-user`	GUBLE_PG_USER	user	guble	The PostgreSQL user
`--pg-password`	GUBLE_PG_PASSWORD	password	guble	The PostgreSQL password
`--pg-dbname`	GUBLE_PG_DBNAME	database	guble	The PostgreSQL database name

Run All Tests

go get -t github.com/smancke/guble/...
go test github.com/smancke/guble/...

Clients

The following clients are available:

Commandline Client: https://github.com/smancke/guble/tree/master/guble-cli
Go client library: https://github.com/smancke/guble/tree/master/client
JavaScript library: (in early stage) https://github.com/smancke/guble-js

Protocol Reference

REST API

Currently there is a minimalistic REST API, just for publishing messages.

POST /api/message/<topic>

URL parameters:

userId: The PublisherUserId
messageId: The PublisherMessageId

Headers

You can set fields in the header JSON of the message by providing the corresponding HTTP headers with the prefix X-Guble-.

Curl example with the resulting message:

curl -X POST -H "x-Guble-Key: Value" --data Hello 'http://127.0.0.1:8080/api/message/foo?userId=marvin&messageId=42'

Results in:

16,/foo,marvin,VoAdxGO3DBEn8vv8,42,1451236804
{"Key":"Value"}
Hello

WebSocket Protocol

The communication with the guble server is done by ordinary WebSockets, using a binary encoding.

Message Format

All payload messages sent from the server to the client are using the following format:

<path:string>,<sequenceId:int64>,<publisherUserId:string>,<publisherApplicationId:string>,<publisherMessageId:string>,<messagePublishingTime:unix-timestamp>\n
[<application headers json>]\n
<body>

example 1:
/foo/bar,42,user01,phone1,id123,1420110000
{"Content-Type": "text/plain", "Correlation-Id": "7sdks723ksgqn"}
Hello World

example 2:
/foo/bar,42,user01,54sdcj8sd7,id123,1420110000

anyByteData

All text formats are assumed to be UTF-8 encoded.
Message sequenceIds are int64, and distinct within a topic. The message sequenceIds are strictly monotonically increasing depending on the message age, but there is no guarantee for the right order while transmitting.

Client Commands

The client can send the following commands.

Send

Publish a message to a topic:

> <path> [<publisherMessageId>]\n
[<header>\n]..
\n
<body>

example:
> /foo

Hello World

Subscribe/Receive

Receive messages from a path (e.g. a topic or subtopic). This command can be used to subscribe for incoming messages on a topic, as well as for replaying the message history.

+ <path> [<startId>[,<maxCount>]]

path: the topic to receive the messages from
startId: the message id to start the replay ** If no startId is given, only future messages will be received (simple subscribe). ** If the startId is negative, it is interpreted as relative count of last messages in the history.
maxCount: the maximum number of messages to replay

Note: Currently, the fetching of stored messages does not recognize subtopics.

Examples:

+ /foo         # Subscribe to all future messages matching /foo
+ /foo/bar     # Subscribe to all future messages matching /foo/bar

+ /foo 0       # Receive all message from the topic and subscribe for further incoming messages.

+ /foo 42      # Receive all message with message ids >= 42
               # from the topic and subscribe for further incoming messages.

+ /foo 0 20    # Receive the first (oldest) 20 messages within the topic and stop.
               # (If the topic has less messages, it will stop after receiving all existing ones.)

+ /foo -20     # Receive the last (newest) 20 messages from the topic and then
               # subscribe for further incoming messages.

+ /foo -20 20  # Receive the last (newest) 20 messages within the topic and stop.
               # (If the topic has less messages, it will stop after receiving all existing ones.)

Unsubscribe/Cancel

Cancel further receiving of messages from a path (e.g. a topic or subtopic).

- <path>

example:
- /foo
- /foo/bar

Server Status Messages

The server sends status messages to the client. All positive status messages start with >. Status messages reporting an error start with !. Status messages are in the following format.

'#'<msgType> <Explanation text>\n
<json data>

Connection Message

#ok-connected You are connected to the server.\n
{"ApplicationId": "the app id", "UserId": "the user id", "Time": "the server time as unix timestamp "}

Example:

#connected You are connected to the server.
{"ApplicationId": "phone1", "UserId": "user01", "Time": "1420110000"}

Send Success Notification

This notification confirms, that the messaging system has successfully received the message and now starts transmitting it to the subscribers:

#send <publisherMessageId>
{"sequenceId": "sequence id", "path": "/foo", "publisherMessageId": "publishers message id", "messagePublishingTime": "unix-timestamp"}

Receive Success Notification

Depending on the type of + (receive) command, up to three different notification messages will be sent back. Be aware, that a server may send more receive notifications that you would have expected in first place, e.g. when:

Additional messages are stored, while the first fetching is in progress
The server decides to meanwhile stop the online subscription and change to fetching, because your client is too slow to read all incoming messages.

When the fetch operation starts:
```
#fetch-start <path> <count>
```
- path: the topic path
- count: the number of messages that will be returned
When the fetch operation is done:
```
#fetch-done <path>
```
- path: the topic path
When the subscription to new messages was taken:
```
#subscribed-to <path>
```
- path: the topic path

Unsubscribe Success Notification

An unsubscribe/cancel operation is confirmed by the following notification:

#canceled <path>

Send Error Notification

This message indicates, that the message could not be delivered.

!error-send <publisherMessageId> <error text>
{"sequenceId": "sequence id", "path": "/foo", "publisherMessageId": "publishers message id", "messagePublishingTime": "unix-timestamp"}

Bad Request

This notification has the same meaning as the http 400 Bad Request.

!error-bad-request unknown command 'sdcsd'

Internal Server Error

This notification has the same meaning as the http 500 Internal Server Error.

!error-server-internal this computing node has problems

Topics

Messages can be hierarchically routed by topics, so they are represented by a path, separated by /. The server takes care, that a message only gets delivered once, even if it is matched by multiple subscription paths.

Subtopics

The path delimiter gives the semantic of subtopics. With this, a subscription to a parent topic (e.g. /foo) also results in receiving all messages of the subtopics (e.g. /foo/bar).

📚 guble - Awesome Go Library for Messaging

Detailed Description of guble