Connection Parameters for AMPS
When specifying a URI for connection to an AMPS server, you may specify a number of transport-specific options in the parameters section of the URI connection parameters. Here is an example:
In this example, we have specified the AMPS instance on localhost, port 9007, connecting to a transport that uses the amps protocol and sending JSON messages. We have also set two parameters: tcp_nodelay, a Boolean (true/false) parameter, and tcp_sndbuf, an integer parameter. Multiple parameters may be combined to finely tune settings available on the transport. Normally, you'll want to stick with the defaults on your platform, but there may be some cases where experimentation and fine-tuning will yield higher or more efficient performance.
The AMPS client supports the value of tcp in the scheme component connection string for TCP/IP connections, and the value of tcps as the scheme for SSL encrypted connections.
For connections that use Unix domain sockets, the client supports the value of unix in the scheme, and requires an additional option, as described in the Unix Transports Parameters section below.
IPv6 Connections
Starting with version 5.3.3.0, the AMPS client supports creating connections over both IPv4 and IPv6 protocols if supported by the underlying Operating System.
By default, the AMPS client will prefer to resolve host names to IPv4 addresses, but this behavior can be adjusted by supplying the ip_protocol_prefer transport option, described in the table below.
TCP and SSL Transport Options
The following transport options are available for TCP connections:
Option
Description
bind
(IP address) Sets the interface to bind the outgoing socket to.
Starting with version 5.3.3.0, both IPv4 and IPv6 addresses are fully supported for use with this parameter.
tcp_rcvbuf
(integer) Sets the socket receive buffer size. This defaults to the system default size. (On Linux, you can find the system default size in /proc/sys/net/core/rmem_default.)
tcp_sndbuf
(integer) Sets the socket send buffer size. This defaults to the system default size. (On Linux, you can find the system default size in /proc/sys/net/core/wmem_default.)
tcp_nodelay
(boolean) Enables or disables the TCP_NODELAY setting on the socket. By default TCP_NODELAY is disabled.
tcp_linger
(integer) Enables and sets the SO_LINGER value for the socket By default, SO_LINGER is enabled with a value of 10, which specifies that the socket will linger for 10 seconds.
tcp_keepalive
(boolean) Enables or disables the SO_KEEPALIVE value for the socket. The default value for this option is true.
ip_protocol_prefer
(string) Influence the IP protocol to prefer during DNS resolution of the host. If a DNS entry of the preferred protocol can not be found, the other non-preferred protocol will then be tried.
If this parameter is not set, the default will be to prefer IPv4.
If an explicit IPv4 address or IPv6 IP address is provided as the host, the format of the IP address is used to determine the IP protocol used and this setting has no effect.
Supported Values:
ipv4: Prefer an IPv4 address when resolving the host
ipv6: Prefer an IPv6 address when resolving the host
This parameter is available starting with version 5.3.3.0.
Unix Transport Parameters
The unix transport type communicates over Unix domain sockets. This transport requires the following additional option:
Option
Description
path
The path to the Unix domain socket to connect to.
Unix domain sockets always connect to the local system. When the scheme specified is unix, the host address is ignored in the connection string. For example, the connection string:
and the connection string:
are equivalent.
The other components of the connection string, including the protocol, message type, username, and authentication token are processed just as they would be for TCP/IP sockets.
AMPS Additional Logon Options
The connection string can also be used to pass logon parameters to AMPS. AMPS supports the following additional logon option:
Option
Description
pretty
Provide formatted representations of binary messages rather than the original message contents.
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