Trimess

Saturday, May 4, 2013

SF LIVE BUS COMES TO PORTLAND

FireMet PDX

8 comments:

Max said...

I think this is really cool; I've thought about making something like this, but I decided against it because I thought TriMet might shut this sort of app down, due to the amount of data being pulled down by the app. We'll see how TriMet responds.

Al M said...

That's interesting MAX, how does the 'amount of data being pulled' affect Trimet negatively?

Jason McHuff said...

Actually, TriMet doesn't have a huge issue with bandwidth. I know there was one app I think they raised the limit for (PDXBus?). And it appears it's getting all the data in one pass, so it's really not that many requests.

But TriMet actually officially has live tracking, though it's limited to 10 routes and does not support MAX (and am a little surprised it's actually technically supported). Go to http://ride.trimet.org/ , open "TriMet Routes" in the left column, select bus routes and look for the bus icon above the top left corner of the map.

In addition, I'm wondering if this map is officially sanctioned as the interface it's using (that shows all buses on a route instead of approaching a stop) is not publicly documented.

Lastly, it should show the vehicle numbers since it says it uses them.

Max said...

Bandwidth and servers cost TriMet money. It's not really a ton of money, but it's not $0 either.

One thing the (SF) app developer did that was clever is that it downloads the data to a centralized database and then feeds THAT data out to all of the clients -- so as far as TriMet is concerned there's just 1 person downloading all of the data every 6 seconds, no matter how many people are actually viewing it.

Still you can imagine if there were lots of apps like this then at some point they'd have to buy another server - which would cost $$, plus more $$ to upgrade/maintain/backup/administer/etc.

... or imagine if they didn't have the smarts to do it the way they did, in that case each client would be pulling all the data every 6 seconds; that could get to be a lot of server load really quickly.

Jason McHuff said...

I looked at the code and it appears that it downloads the data directly to every user

Jason McHuff said...

Also, if you watch the map, some of the vehicle icons bounce back and forth

Max said...

Jason: It works the way I said it does; if you disagree, feel free to provide evidence to the contrary.

Jason McHuff said...

Looking at the actual data requests from my browser, I think you may be right. I'm guessing I was actually looking at the code that runs on this person's server, and not the code that individual users get.