Connection Strings For AMPS

The AMPS clients use connection strings to determine the server, port, transport, and protocol to use to connect to AMPS. When the connection point in AMPS accepts multiple message types, the connection string also specifies the precise message type to use for this connection.

Connection strings have a number of elements:

As shown in the figure above, connection strings have the following elements:

• Transport - Defines the network used to send and receive messages from AMPS. In this case, the transport is wss.

  ws (WebSocket) and wss (WebSocket Secure) are the only supported transports for the JavaScript client.

• Host Address - Defines the destination on the network where the AMPS instance receives messages. The format of the address is dependent on the transport. For ws and wss, the address consists of a host name and port number. In this case, the host address is localhost:9007.

• Protocol - Sets the format in which AMPS receives commands from the client. Most code uses the default amps protocol, which sends header information in JSON format. AMPS supports the ability to develop custom protocols as extension modules, and AMPS also supports legacy protocols for backward compatibility.

• Message Type - Specifies the message type that this connection uses. This component of the connection string is required if the protocol accepts multiple message types and the transport is configured to accept multiple message types. If the protocol does not accept multiple message types, this component of the connection string is optional, and defaults to the message type specified in the transport.

  Legacy protocols such as fix, nvfix and xml only accept a single message type, and therefore do not require or accept a message type in the connection string.

The JavaScript client does not support legacy protocols, the amps protocol is required.

As an example, a connection string such as:

ws://localhost:9007/amps/json

would work for programs connecting from the local host to a Transport configured as follows:

<AMPSConfig>
...

<Protocols>
    ...

    <!-- This protocol is using the websocket module,which is
    required for JavaScript client. -->
    <Protocol>
        <Name>websocket-any</Name>
        <Module>websocket</Module>
    </Protocol>

</Protocols>

...

<Transports>
    ...

    <!-- This transport accepts any known message type for
    the instance: the client must specify the message type. -->
    <Transport>
        <Name>websocket-any</Name>
        <Type>tcp</Type>
        <InetAddr>9007</InetAddr>
        <Protocol>websocket-any</Protocol>
    </Transport>

</Transports>

...

</AMPSConfig>

See the Configuring Transports and Configuring Protocols sections in the AMPS User Guide for more information on configuring transports and protocols.