nexus

README

WAMP v2 router library, client library and router service

nexus is a WAMP v2 router library, client library, and a router service, that implements most of the features defined in the WAMP-protocol advanced profile. The nexus project is written in Go and designed for highly concurrent asynchronous I/O. The nexus router provides extended functionality. The router and client interoperate with other WAMP implementations.

Documentation

See the nexus project Wiki for documentation, examples, and operational details.

for API documentation.

What is WAMP and nexus

The Web Application Messaging Protocol (WAMP) is an open standard WebSocket subprotocol that provides two application messaging patterns in one unified protocol: Remote Procedure Calls and Publish & Subscribe. WAMP is also referred to as WAMP-proto it distinguish it from [other uses](https://en.wikipedia.org/wiki/WAMP_(disambiguation) of the acronym.

Using WAMP you can build distributed systems out of application components which are loosely coupled and communicate in (soft) real-time.

Nexus is a software package that provides a WAMP router library, client library, and stand-alone WAMP router service. This nexus package provides a messaging system for building distributed applications and services. Endpoints using websockets, TCP sockets, Unix sockets, and in-process connections may all communicate with each other via pub/sub and routed RPC messaging.

• The router library can be used to build custom WAMP routers or to embed a WAMP router in an application.
• The client library can be used to build clients that connect to any WAMP server, or to communicate in-process with a WAMP router embedded in the same application.
• The router service can be run as-is to provide WAMP routing.

Installation

Install nexusd router service from source

go get -d github.com/dtegapp/nexus/nexusd
cd ${GOPATH}/src/github.com/dtegapp/nexus/nexusd
make install

Run nexusd -help to see usage information. Although nexusd can be run using only command line flags, a configuration file offers much more configurability.

Create configuration file and run nexusd service

cp ${GOPATH}/src/github.com/dtegapp/nexus/nexusd/etc/nexus.json ./
vi nexus.json
nexusd -c nexus.json

Install examples to run and test with

git clone git@github.com:dtegapp/nexus.git
cd nexus/examples

Building routers and clients with nexus

The nexus router library is used to build a WAMP router or embed one in your service. The nexus client library is used to build WAMP clients into you goloang applications. To use either of these libraries, import the v3 version of the appropriate packages. Version v3 is the only currently supported version.

import (
	"github.com/dtegapp/nexus/v3/client"
	"github.com/dtegapp/nexus/v3/wamp"
)

Run nexusd from a container

Pull the nexusd container image built with the latest code version and run the container:

docker pull ghcr.io/dtegapp/nexusd:latest
docker run ghcr.io/dtegapp/nexusd:latest

Now it just works. By default, the router accepts connections on port 8080 and allows anonymous communication with clients using realm1. You can change the values or get help by passing options to the container process:

docker run ghcr.io/dtegapp/nexusd:latest --ws 0.0.0.0:8888 --realm autobahn
docker run ghcr.io/dtegapp/nexusd:latest --help

Alternatively, you can mount the nexusd configuration file to the container, and get a more customizable and secure environment. See the nexusd configuration reference for details. Finally, you can also run the container process as an unprivileged user.

Examples

Look at the examples to see how to create simple clients and servers. Follow the README.md in the nexus/examples directory. Examples of using advanced profile features are also available in the wiki documentation.

https://github.com/dtegapp/nexus/tree/v3/examples

The examples include interoperability examples to demonstrate nexus working with different WAMP implementations. Each of these has its own README.md that describes how to set up the environment and run the examples.

https://github.com/dtegapp/nexus/tree/v3/examples/interop

The nexusd service is also an example stand-alone WAMP router. All the router options are configurable in nexusd using a configuration file, and one is provided in the nexusd/etc/ directory. This can be used as starting point to write your own WAMP router service.

https://github.com/dtegapp/nexus/tree/v3/nexusd

Contributing

Please read the Contributing guide if you are interested in becoming a contributor to this project.

Please report any problems, or request changes and new functionality by opening an issue.

Nexus Features

• Concurrent Asynchronous I/O Nexus supports large numbers of clients concurrently sending and receiving messages, and never blocks on I/O, even if a client becomes unresponsive. See Router Concurrency and Client Concurrency for details.
• WAMP Advanced Profile Features This project implements most of the advanced profile features in WAMP v2. See current feature support provided by nexus. Nexus also offers extended functionality for retrieving session information and for message filtering, giving clients more ability to decide where to send messages.
• Flexibility Multiple transports and serialization options are supported, and more are being developed to maximize interoperability. Currently, nexus provides websocket, rawsocket (tcp and unix), and local (in-process) transports. JSON, MessagePack, and CBOR serialization is available over websockets and rawsockets.
• Security TLS is available over websockets and rawsockets with client and server APIs that allow configuration of TLS. The nexus router library also provides interfaces for integration of client authentication and authorization logic.

Status

The currently maintained version of this module is 3.x. Earlier major versions are no longer supported.

Advanced Profile Feature Support

RPC Features

Feature	Supported
progressive_call_results	Yes
progressive_call_invocations	Yes
call_timeout	Yes
call_canceling	Yes
caller_identification	Yes
call_trustlevels	No
registration_meta_events	Yes
registration_meta_procedures	Yes
pattern_based_registration	Yes
shared_registration	Yes
sharded_registration	No
registration_revocation	No
procedure_reflection	No
payload_passthru_mode	Yes

PubSub Features

Feature	Supported
subscriber_blackwhite_listing	Yes
publisher_exclusion	Yes
publisher_identification	Yes
publication_trustlevels	No
subscription_meta_events	Yes
subscription_meta_procedures	Yes
pattern_based_subscription	Yes
sharded_subscription	No
event_history	Yes
topic_reflection	No
testament_meta_api	Yes
payload_passthru_mode	Yes

Other Advanced Features

Feature	Supported
rawsocket (TCP & Unix) transport	Yes
session meta events	Yes
session meta procedures	Yes
TLS for websockets	Yes
TLS for rawsockets	Yes
challenge-response authentication	Yes
cookie authentication	Yes
ticket authentication	Yes
batched WS transport	No
longpoll transport	No
websocket compression	Yes

Extended Functionality

Nexus provides extended functionality around subscriber black/white listing and in the information available via the session meta API. This enhances the ability of clients to make decisions about message recipients.