Is there a canon source that describes a galaxy-wide computer network in the Star Wars galaxy?
Does it mention how big the internet is in the galaxy?
Is there a canon source that describes a galaxy-wide computer network in the Star Wars galaxy?
Does it mention how big the internet is in the galaxy?
In Disney Canon? Not really, no.
The Holonet was a communication network that transmitted holograms around the Empire. In Tarkin, the holonet is restricted to the Empire only, and in various episodes of Rebels the plot surrounds taking over broadcast stations to send Rebel propaganda, which makes the Holonet look like cable television.
But the Holonet is also responsible for ship to ship hologrammatic transmissions; the holograms in Empire Strikes Back are Holonet transmissions; the transmission of Darth Sidius in The Phantom Menace also also via Holonet.
(In Legends, it's explained that the Holonet operates in hyperspace, which is why communication is so fast. Subspace communications are slower, and "mail" only goes the speed of whatever ship it's on.)
Now, we do see droids communicating with comlinks occasionally, so it's not beyond the pale to imagine that droids could connect to each other via comlinks to communicate.
Limiting to Disney Canon, though, computers are treated as monolithic mainframes with huge databases, where data has to be retrieved either online (via connected terminals) or transferred via physical storage (Rogue One). Data transfer is handled by a "sneakernet," with data updates carried by ship to other mainframes, which update their local databases (kinda like usenet newsgroups before the Internet).
They have something called the Holo-Net. It seems to only exist in the core worlds region of space (where Coruscant is) because other planets like Tatooine don't have it. Most spaceships seem to be able to access it with their communication systems (like the Millennium Falcon with it's big radar dish), probably to get hyperspace coordinates and to study galaxy chart information (like universal gps for planet locations, like Han does on the Millennium Falcon in Empire Strikes Back).