Day III - consuming streams

EventStoreDB
#1

So I’ve a nice pretty dashboard about to be populated by the projections I’ve created - and now I want to at the bottom show the live events by consuming the stream directly

I’ve got

/streams/github?format=json

I see we have links to prev/next, although prev appears to step foward in time in the stream and ‘next’ appears to step backwards in time - which is contrary to what the docs say

My links

image.png

Documentation links

I assume at some point this behaviour changed

Regardless, I don’t think I use the links if I’m to consume this stream from my app - instead I should be polling regularly from the ‘last seen id’ and stepping forward in the stream until I receive fewer events than I asked for - correct?

I can even model this as a stream in node.js - fancy that.

image.png

#2

Also, am I going to get put on Santas naughty list for doing this?

fromStream('github')
  .whenAny(function(s, e) {
     if(!e.body) return
     if(!s.events) s.events = []
     s.events.push(e.body)
     while(s.events.length > 20)
       s.events.shift()
   })
#3

(Or in other words, I assume there is a better way to ask “Get me the 20 most recent ones please”)

#4

why not just read the twenty most recent from the stream?

#5

As mentioned above, when I ask for /streams/github I’m not given the most recent, I can page forward still quite a lot and I was wondering why this was

#6

I was expecting to be able to poll

/streams/github?format=json

And just shove the data directly into my realtime visualisation (as old entries would naturally just disappear)

#7

Let me check why it returns data from the beginning.

#8

that should work that way… your receing the oldest event first?

#9

yes lets verify …

#10

Okay, I know what is happening - I thought I had stopped the process that was pumping events into the store, I hadn’t, I had merely backgrounded it

So by the time I got to look at the stream, there were more events in there

Pebcak

herp derp derp

#11

:slight_smile:

#12

On that note though, if I am looking at the event stream - I am getting a load of links to those events, whereas my soul-destroying projection gives me an array of the actual events themselves

What is the Approved Method of getting the stream of actual events themselves rather than links to the events?

#13

Or is that “Just query for the goddamned events and put a goddamned proxy in there because they’re cacheable”

#14

we will be adding this (have a card) though let me explaon why links… it seems inefficient at first but think about it from a http caching perspective…

#15

also you have http keepalives and pipelining :slight_smile:

#16

That’s what I thought, it’s much better than constantly querying a stream that has to create itself out of events rather than looking at (mostly) cached events

#17

I do indeed, providing I can find the documentation for doing that sort of thing in node

#18

http 1.1 does by default

#19

https://groups.google.com/forum/?fromgroups=#!msg/nodejs/z0xMSW5riDI/9FPg6HlCbLMJ

#sadface

#20

still has single connection though :slight_smile: