1. OpenSRF 3.1.0-beta

OpenSRF 3.1.0-beta was released on 9 January 2019. This is a major release adding several new features and fixing serveral bugs.

1.1. New Features and Major Bugfixes

1.1.1. Support for Websocketd (LP#1777180)

OpenSRF 3.1 adds support for websocketd as a backend providing a WebSocket gateway for OpenSRF requests. websocketd offers significant reliability improvements over Apache’s mod_websocket, which is no longer recommended for production use.

1.1.2. Request Backlog Queues (LP#1729610)

Perl and C service listeners now have the ability to queue requests that cannot be immediately handled because no drones are available. This allows services to handle transitory spikes in incoming requests while conserving expensive resources such as database connections.

The request backlog queue is used when a service has reached the drone count set by its max_children setting and all of its drones are handling other requests. The backlog queue is FIFO, so Once a drone becomes available, it will process the oldest queued request.

Each service’s backlog queue can contain 1,000 requests by default; this limit can be adjusted using the max_backlog_queue service setting.

If the backlog queue would grow beyond its limit, incoming requests that would be added to it are instead dropped. When a request is dropped, an OpenSRF method exception response is sent back to the client. This exception has a status code of 503 ("service unavailable") and is provided to give clients the opportunity to pause sending requests or display a useful error message to the user.

This feature includes two new example services, opensrf.cslow and opensrf.slooooooow, written in C and Perl respectively. Both services have a "wait" method that waits for a specified number of seconds, then returns that number. These services can be used for testing the backlog queue and simulating long-running methods during performance testing of OpenSRF applications.

1.1.3. Ability to Force-Recyle Drones (LP#1706147)

Perl applications now allow a method to indicate that the drone running it be recycled upon completion of that method. This allows methods that are known to require a long time to run or consume (or leak) significant amounts of memory to force system resources to be returned upon completion.

Perl methods that wish to force drone-reycling can do so like this:

sub some_api_method {
    my ($self, $client, ...) = @_;

1.1.4. Changes to Supported Linux Distributions (LP#1793585 and LP#1718459)

Support for Ubuntu 18.04 "Bionic Beaver" has been added, while support for Debian Wheezy has been dropped.

Users of Ubuntu 14.04 ("Trusty Tahr") should note that Trusty will reach end of life in April 2019 and that OpenSRF support for Tahr will end in a subsequent release in the 3.1.x series.

1.1.5. Support Modern Ejabberd (LP#1703411)

Modern versions of Ejabberd strip custom XML attributes which appear outside of custom elements. To support OpenSRF’s custom router and osrf_xid commands, these attribute are now moved into a new custom XML element <opensrf>.

1.1.6. Improved Example NGINX Configuration (LP#1711145)

The example NGINX reverse proxy configuration file that ships with OpenSRF is significantly improved:

  • Implements HTTPS security recommendations from Mozilla

  • Enables http2

  • Applies a 5-minute proxy read timeout to avoid too-short timeouts on long API calls.

  • Adds a (commented) section on sending NGINX logs to syslog

1.1.7. OpenSRF HTTP Translator Can Now Access User Agent IP Address (LP#1684970)

The OpenSRF HTTP translator can now obtain the user agent’s IP address (as opposed to the IP address of the proxy) when running behind a reverse proxy. This fixes a problem where it is theoretically possible for two clients to access the same OpenSRF worker process over the HTTP translator. This also fixes a problem where proxied requests could various see the IPv4 and IPv6 forms of the proxy’s address, potentially breaking long-running transactions made through the translator.

This fix requires use of the mod_remoteip Apache module.

1.1.8. Other Bugs Fixed

  • The JavaScript client library now detects when a transport error occurs when making a WebSocket request and invokes either the transport or generic error handler, depending on what has been set by the client. (LP#1776510)

  • OpenSRF could fail to retrieve memcached values whose keys contain the % character. This resulted in breaking authentication in Evergreen when the username or barcode contained a %. (LP#1684970)

1.2. Upgrade Notes

OpenSRF 3.1 introduces changes to the application binary interface (ABI) for C applications. Consequently, Evergreen users should plan on recompiling Evergreen after installing OpenSRF 3.1.

Users of NGINX should review the examples/nginx/osrf-ws-http-proxy example configuration file and make adjustments to their example configuration accordingly, including generating a new DH Group using the openssl dhparam command.

Users of a reverse proxy such as NGINX should install and enable the Apache mod_remoteip module, then adjust the Apache configuration to include lines like this:

    RemoteIPInternalProxy # or whatever the proxy IP address is
    RemoteIPInternalProxy ::1          # or whatever the proxy IP address is
    RemoteIPHeader X-Real-IP

1.3. Note for Evergreen Users

OpenSRF 3.1 can be used by Evergreen 3.0.x, 3.1.x, and 3.2.x.

1.4. Acknowledgements

We would like to thank the following people who contributed to OpenSRF 3.0.0:

  • Galen Charlton

  • Jeff Davis

  • Bill Erickson

  • Mike Rylander

  • Chris Sharp

  • Ben Shum

  • Remington Steed

  • Jason Stephenson