J.4. Leaving 0.x territory

August 2002: first stable tree: NUT 1.0.0

After nearly 5 years of having a 0.x version number, 1.0.0 was released on August 19, 2002. This milestone meant that all of the base features that you would expect to find were intact: good hardware support, a network server with security controls, and system shutdowns that worked.

The design was showing signs of wear from the rapid expansion, but this was intentionally ignored for the moment. The focus was on getting a good version out that would provide a reasonable base while the design issues could be addressed in the future, and I’m confident that we succeeded.

November 2002: second stable tree: NUT 1.2.0

One day after the release of 1.0.0, 1.1.0 started the new development tree. During that development cycle, the CGI programs were rewritten to use template files instead of hard-coded HTML, thus bringing back the flexibility of the original unreleased prototype from 5 years before. The multimon was removed from the tree, as the new upsstats could do both jobs by loading different templates.

A new client library called upsclient was created, and it replaced upsfetch. This new library only supported TCP connections, and used an opaque context struct to keep state for each connection. As a result, client programs could now do things that used multiple connections without any conflicts. This was done primarily to allow OpenSSL support, but there were other benefits from the redesign.

upsd and the clients could now use OpenSSL for basic authentication and encryption, but this was not included by default. This was provided as a bonus feature for those users who cared to read about it and enable the option, as the initial setup was complex.

After the 1.1 tree was frozen and deemed complete, it became the second stable tree with the release of 1.2.0 on November 5, 2002.

April 2003: new naming scheme, better driver glue, and an overhauled protocol

Following an extended period with no development tree, 1.3.0 got things moving again on April 13, 2003. The focus of this tree was to rewrite the driver-server communication layer and replace the static naming scheme for variables and commands.

Up to this point, all variables had names like STATUS, UTILITY, and OUTVOLT. They had been created as drivers were added to the tree, and there was little consistency. For example, it probably should have been INVOLT and OUTVOLT, but there was no OUTVOLT originally, so UTILITY was all we had. This same pattern repeated with ACFREQ — is it incoming or outgoing? — and many more.

To solve this problem, all variables and commands were renamed to a hierarchical scheme that had obvious grouping. STATUS became ups.status. UTILITY turned into input.voltage, and OUTVOLT is output.voltage. ACFREQ is input.frequency, and the new output.frequency is also now supported. Every other variable or command was renamed in this fashion.

These variables had been shared between the drivers and upsd as values. That is, for each name like STATUS, there was a #define somewhere in the tree with an INFO_ prefix that gave it a number. INFO_STATUS was 0x0006, INFO_UTILITY was 0x0004, and so on, with each name having a matching number. This number was stored in an int within a structure which was part of the array that was either written to disk or shared memory.

That structure had several restrictions on expansion and was dropped as the data sharing method between the drivers and the server. It was replaced by a new system of text-based messages over Unix domain sockets. Drivers now accepted a short list of commands from upsd, and would push out updates asynchronously. upsd no longer had to poll the state files or shared memory. It could just select all of the driver and client fds and act on events.

At the same time, the network protocol on port 3493 was overhauled to take advantage of the new naming scheme. The existing "REQ STATUS@su700", "ANS STATUS@su700 OL" scheme was showing signs of age, and it really only supported the UPS name (@su700) as an afterthought. The new protocol would now use commands like GET and LIST, leading to exchanges like "GET VAR su700 ups.status" and "VAR su700 ups.status OL". These responses contain enough data to stand alone, so clients can now handle them asynchronously.

July 2003: third stable tree: NUT 1.4.0

On July 25, 2003, 1.4.0 was released. It contained support for both the old "REQ" style protocol (with names like STATUS), and the new "GET" style protocol (with names like ups.status). This tree is provided to bridge the gap between all of the old releases and the upcoming 2.0.

2.0 will be released without support for the old REQ/STATUS protocol. The hope is that client authors and those who have implemented their own monitoring software will use the 1.4 cycle to change to the new protocol. The 1.4 releases contain a lot of compatibility code to make sure both work at the same time.

July 2003: pushing towards 2.0

1.5.0 forked from 1.4.0 and was released on July 29, 2003. The first changes were to throw out anything which was providing compatibility with the older versions of the software. This means that 1.5 and the eventual 2.0 will not talk to anything older than 1.4.

This tree continues to evolve with new serial routines for the drivers which are intended to replace the aging upscommon code which dates back to the early 0.x releases. The original routines would call alarm and read in a tight loop while fetching characters. The new functions are much cleaner, and wait for data with select. This makes for much cleaner code and easier strace/ktrace logs, since the number of syscalls has been greatly reduced.

There has also been a push to make sure the data from the UPS is well-formed and is actually usable before sending updates out to upsd. This started during 1.3 as drivers were adapted to use the dstate functions and the new variable/command names. Some drivers which were not converted to the new naming scheme or didn’t do sanity checks on the incoming UPS data from the serial port were dropped from the tree.

This tree was released as 2.0.0.