Servlet Engine

Table of Contents

Servlet Engine

Name | Address | Max Connections | Connection Keepalive Timeout | Environment | Initial Request Timeout (secs) | Retry Timeout (secs) | Response Buffering

Name

Description

A unique name for this external application. You will refer to it by this name when you use it in other parts of the configuration.

Address

Description

A unique socket address used by the external application. IPv4/IPv6 sockets and Unix Domain Sockets (UDS) are supported. IPv4/IPv6 sockets can be used for communication over the network. UDS can only be used when the external application resides on the same machine as the server.

Syntax

IPv4 or IPV6 address:port or UDS://path

Example

127.0.0.1:5434
UDS://tmp/lshttpd/php.sock.

Tips

If the external application runs on the same machine, UDS is preferred. If you have to use an IPv4|IPV6 socket, set the IP address to localhost or 127.0.0.1, so the external application is inaccessible from other machines.
Unix Domain Sockets generally provide higher performance than IPv4 sockets.

Max Connections

Description

Specifies the maximum number of concurrent connections that can be established between the server and an external application. This setting controls how many requests can be processed concurrently by an external application, however, the real limit also depends on the external application itself. Setting this value higher will not help if the external application is not fast enough or cannot scale to a large number of concurrent requests.

Syntax

Integer number

Tips

Setting a high value does not directly translate to higher performance. Setting the limit to a value that will not overload the external application will provide the best performance/throughput.

Connection Keepalive Timeout

Description

Specifies the maximum time in seconds to keep an idle persistent connection open.

When set to "-1", the connection will never timeout. When set to 0 or greater, the connection will be closed after this time in seconds has passed.

Syntax

int

Environment

Description

Specifies extra environment variables for the external application.

Syntax

Key=value. Multiple variables can be separated by "ENTER"

Initial Request Timeout (secs)

Description

Specifies the maximum time in seconds the server will wait for the external application to respond to the first request over a new established connection. If the server does not receive any data from the external application within this timeout limit, it will mark this connection as bad. This helps to identify communication problems with external applications as quickly as possible. If some requests take longer to process, increase this limit to avoid 503 error messages.

Syntax

Integer number

Retry Timeout (secs)

Description

Specifies the period of time that the server waits before retrying an external application that had a prior communication problem.

Syntax

Integer number

Response Buffering

Description

Specifies whether to buffer responses received from external applications. If a "nph-" (Non-Parsed-Header) script is detected, buffering is turned off for responses with full HTTP headers.

Syntax

Select from drop down list