examples/

Nexus Examples

Simple Example

The simple example contains a very simple websocket server, and simple websocket subscriber and publisher clients. This is a good place to start seeing how to build WAMP servers and clients using nexus.

The simple examples can be run from the examples directory by running:

1. Run the server with go run simple/server.go
2. Run the subscriber with go run simple/sub/subscriber.go
3. Run the publisher with go run simple/pub/publisher.go

Example Server and Clients

The project Wiki provides a walk-through of client and server example code.

The example server, in the server directory, runs a websocket (with and without TLS), tcp raw socket (with and without TLS), and unix raw socket transport at the same time. This allows different clients to communicate with each other when connected to the server using any combination of socket types, TLS, and serialization schemes.

The example clients are located in the following locations:

• pubsub/subscriber/
• pubsub/publisher/
• rpc/callee/
• rpc/caller/

When connecting a client, set the URL scheme with -scheme= to specify the type of transport, and whether or not to use TLS:

• Websocket: -scheme=ws
• Websocket + TLS: -scheme=wss
• TCP socket: -scheme=tcp
• TCP socket + TLS: -scheme=tcps
• Unix socket: -socket=unix

If no scheme is specified, then the default is ws (websocket without TLS).

When using TLS ("wss" or "tcps" schemes), certificate verification fails when using a certificate that cannot be verified. For verification of the server's certificate to work, it is necessary to trust the server's certificate by specifying -trust=server/cert.pem. Verification can also be skippen using the -skipverify flag. Example running subscriber client:

go run pubsub/subscriber/subscriber.go -scheme=wss -trust=server/cert.pem

To choose the type of serialization for the client to use, specify -serialize=json or -serialize=msgpack. If no serialization is specified, then the default is json.

NOTE: The certificate and key used by the example server were created using the following commands:

openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem -days 3650
openssl rsa -in key.pem -out rsakey.pem

RPC Example

The RPC example provides a callee client as both an external and internal client. An internal client is one that is embedded in the same process as the WAMP router, and does not require a socket or serialization.

Caller and Callee Both External Clients

1. Run the server with go run server/server.go
2. Run the callee with go run rpc/callee/callee.go
3. Run the caller with go run rpc/caller/caller.go

Server with Internal Callee and External Caller.

1. Run the server with go run rpc/server_embedded_callee/server.go
2. Run the caller with go run rpc/caller/caller.go

This server example only runs a websocket transport.

Pub/Sub Example

The pub/sub example provides a subscriber client and a publisher client that connect to the nexus server to demonstrate simple pub/sub messaging.

Run the Subscriber and Publisher Clients

1. Run the server with go run server/server.go
2. Run the subscriber with go run pubsub/subscriber/subscriber.go
3. Run the publisher with go run pubsub/publisher/publisher.go

Multiple Transport Example

A nexus router is capable of routing messages between clients running with different transports and serializations. To see this, you can run the example nexus server and then connect clients that use different combinations of websockets and raw sockets, and JSON and MsgPack serialization.

Run Websocket Subscriber with TCP and Unix Raw Socket Publishers

1. Run the server with go run server/server.go
2. Run the subscriber with go run pubsub/subscriber/subscriber.go
3. Run a publisher with go run pubsub/publisher/publisher.go -socket=tcp
4. Run a publisher with go run pubsub/publisher/publisher.go -socket=unix

Try different combinations socket type, TLS, and serialization with multiple clients.