Resolver Command Line Tool

The resolver command line tool allows you to query and update the resolver server from the command line. There are several kinds of querys/manipulations it can perform,

list: list entries matching a specified pattern
table: query the table descriptor for a path
resolve: see what a path resolves to
add: add a new entry
remove: remove an entry

List

netidx resolver list /solar/stats/*

This sub command allows listing items in the resolver server that match a specific pattern. It supports the full unix glob pattern set, including ** meaning any number of intermediate parents, and {thing1, thing2, thing3, ..} for specifying specific sets. e.g. on my machine I can get all the names under the /solar namespace that begin with battery with the following query,

$ netidx resolver list /solar/**/battery*
/solar/settings/battery_charge_current_limit
/solar/stats/battery_v_max_daily
/solar/stats/battery_current_net
/solar/stats/battery_voltage_slow
/solar/stats/battery_voltage_settings_multiplier
/solar/stats/battery_sense_voltage
/solar/stats/battery_v_min_daily
/solar/stats/battery_temperature
/solar/stats/battery_terminal_voltage

Args

List supports several arguments,

-n, --no-structure: don't list matching items that are structural only. Only list items that are actually published.
-w, --watch: don't quit, instead wait for new items matching the pattern and print them out as they appear.

Table

This prints out the table desciptor for a path, which can tell you how a given path will look in the browser by default. An example 10 row 5 column table generated by the stress publisher looks like this,

$ netidx resolver table /bench
columns:
2: 10
0: 10
1: 10
4: 10
3: 10
rows:
/bench/3
/bench/5
/bench/6
/bench/9
/bench/8
/bench/7
/bench/2
/bench/4
/bench/1
/bench/0

in the columns section, the number after the column name is the number of rows in the table that have that column. Since this table is fully populated every column is associated with 10 rows.

Resolve

Given a path(s) this prints out all the information the resolver server has about that path. This is what the subscriber uses to connect to a publisher, and as such this tool is useful for debugging subscription failures. Using the same stress publisher we saw above we can query one cell in the table.

[eric@blackbird ~]$ netidx resolver resolve /local/bench/0/0
publisher: Publisher { resolver: 127.0.0.1:4564, id: PublisherId(3), addr: 127.0.0.1:5011, hash_method: Sha3_512, target_auth: Local }
PublisherId(3)

First all the publisher records are printed. This is the full information about all the publishers that publish the requested paths. Then, a list of publisher ids is printed, this is the publisher id that corresponds to each path in the order the path was specified. If we asked for two paths under the /local/bench namespace then we will see how this works.

[eric@blackbird ~]$ netidx resolver resolve /local/bench/0/0 /local/bench/0/1
publisher: Publisher { resolver: 127.0.0.1:4564, id: PublisherId(3), addr: 127.0.0.1:5011, hash_method: Sha3_512, target_auth: Local }
PublisherId(3)
PublisherId(3)

Here we can clearly see that the same publisher (publisher id 3) is the one to contact about both requested paths. This output closely mirrors how the actual information is sent on the wire (except on the wire it's binary, and the ids are varints). If multiple publishers published any of the requested paths, their ids would appear on the same line separated by commas.

In the case that nothing is publishing the requested path then the tool will print nothing and exit.

Add

This is a low level debugging tool, and it's really not recommended unless you know exactly what you're doing. Using it could screw up subscriptions to whatever path you add for some time. That said, it's pretty simple,

netidx resolver add /path/to/thing 192.168.0.5:5003

This entry will time out after a while because no publisher is there to send heartbeats for it.

Note this will not work if your system is kerberos enabled, because the resolver server checks that the publisher is actually listening on the address it claims to be listening on, and that obviously can't work in this case.

Remove

This is actually worse than add in terms of danger, because you can remove published things without the publisher knowing you did it, and as a result you can make subscriptions fail until the publisher is restarted. It also doesn't work if you are using kerberos, so that's something.

netidx resolver remove /path/to/thing 192.168.0.5:5003`

Introduction to Netidx