Module pvws 

A PV Web Socket server in the dialect of https://github.com/ornl-epics/pvws.

Clients send subscribe, clear, write, list and echo messages and get one update per changed PV: full metadata first, then only what changed. Like PVWS, an update with neither value nor text means the PV is not connected.

Structs

Changed 🔒

The PVs that changed since a client last heard, and a wake-up for it.

ClientSlot 🔒

Counts a connected client until dropped.

Config

Hub

What every client connection shares.

Pace 🔒

Paces a client’s new subscriptions: each spends a token, and tokens come back at SUBSCRIBE_RATE a second up to SUBSCRIBE_BURST.

Sub 🔒

SubSlot 🔒

Subs 🔒

One client’s subscriptions.

Constants

MAX_CLIENTS 🔒

The most clients connected at once.

MAX_MESSAGE 🔒

The largest message a client may send.

MAX_NAME 🔒

The longest PV name accepted.

MAX_PVS 🔒

The most PVs one client may subscribe to.

MAX_TOTAL_PVS 🔒

The most PVs all clients together may subscribe to.

SEND_TIMEOUT 🔒

The longest one message to a client may take to send before the client is dropped.

SUBSCRIBE_BURST 🔒

New PVs one client may subscribe to at once …

SUBSCRIBE_RATE 🔒

… and each second after that: more are delayed, not refused.

Functions

browser_allowed 🔒

Whether a request comes from a page of this server or an allowed origin, by a name of this server; a request without an Origin is not from a browser page.

client_key 🔒

The address clients are counted by: an IPv4 address (also when mapped into IPv6), or the /64 network of an IPv6 one, as one machine may hold all of a /64.

encode_value 🔒

error 🔒

fits_i32 🔒

handle 🔒

Act on one client message, returning any replies.

host_allowed 🔒

Whether browsers may call this server host (lowercase, no port).

host_name 🔒

The host of a host[:port], keeping the brackets of an IPv6 address.

info

machine_names 🔒

This machine’s names: as the kernel and /etc/hostname have them, each without its domain, and in each domain of /etc/resolv.conf.

names_of 🔒

Every name of a machine called hostnames in domains: exact names only, so ws01.evil.com is not ws01.site.org.

new_names 🔒

How many PVs a message subscribes to that the client does not have.

normalise_origin 🔒

An origin in one spelling: lowercase, no trailing /, no default port.

number 🔒

A double as PVWS sends it: non-finite values as text.

resolv_domains 🔒

The domains of a resolv.conf: its domain and search lines.

same_range 🔒

Whether two limit pairs are equal, with NaN equal to NaN (unset alarm limits are NaN, which would otherwise be sent on every update).

same_value 🔒

Whether two values are equal, without comparing arrays that are the same allocation element by element, and with NaN equal to NaN.

send 🔒

Send one message, giving up on a client that takes too long to take it.

send_all 🔒

send_updates 🔒

Tell the client about every PV that changed since it last heard.

serve 🔒

served_scheme 🔒

Whether a client may have name from this server: not loc:// PVs, which would live here for ever and be shared by every client, nor sim:// ones, which cost the server for nothing, nor formulas, which could read the server’s loc:// PVs. A page makes all three itself.

severity 🔒

socket

strip_default_port 🔒

token_ok 🔒

Whether given is the write token, without stopping at the first difference.

update 🔒

The update message taking a client from last to s, if anything it would see changed.

updates 🔒

The updates for the PVs that changed since the client last heard.

valid_name 🔒

Whether name is a plausible PV name: not too long, and only printable ASCII with no spaces.

vtype 🔒

write_error 🔒

An error naming the PV a write was refused for, so the page can show it by the PV as well as log it.

write_text 🔒

A written value as the text Pv::write takes; whole numbers lose their .0 so integer PVs accept them.