inter.js

var app = require('app')
var assert = require('assert')
var db  = app.db;


var get_state = function(cb) {
    
    db.get('_state', function(err,doc) {
        
        if(err) {
            console.log("processed_seq does not exist");
            cb(null, 0);
        }
        else {
            var seq = doc.processed_seq;

            console.log("processed sequence = "+seq);
            if(seq)
                cb(null, seq);
            else
                cb(new Error("uups"), 0);
        }
    });
}

var set_state = function(seq, cb) {
    
    db.get('_state', function(err,doc) {
        
        if(err) {
            console.log("processed_seq does not exist");
            db.save('_state', {processed_seq:seq}, function(e, res) {
              console.log("created state document");
              cb(null, seq)
            });
        }
        else {
            var rev = doc._rev;
            db.save('_state',rev, {processed_seq: seq}, function(e,res){
              console.log("saved state@" + rev + " = "+ seq);
              cb(null, seq)
            });
   
        }
    });
}

// retrieve changes
var act_on_changes = function() {

    get_state(function(e, seq) {
    
        console.log("get state = " + seq);

        var opts = {filter: 'documents/all'};
        if (seq) opts.since = seq;

        db.changes(opts).on('response',function(res) {
            res.on('data',function(change) {
                console.log("changes:");
                console.log(change);
                console.log("save_seq = " + seq);
                newseq = Math.max(change.seq, seq);
    
                // persist procecced changes
                set_state(newseq, function(err, s) {
                    console.log("saved seq = " + s);
                });

            });
            res.on('end', function() {
                console.log("oops, connection closed");
            });
        });
    });
};

// loop
act_on_changes();

processed_seq does not exist
get state = 0
changes:
{ seq: 2,
id: '3d75a794b4d0fe5d661444917b34d231',
changes: [ { rev: '1-bdcf2a2b6b42e36aa2c3f068345a57ff' } ] }
save_seq = 0
changes:
{ seq: 5,
id: '3d75a794b4d0fe5d661444917b34c5fe',
changes: [ { rev: '1-20c692ec75ac9135e40b74fb12028b11' } ] }
save_seq = 0
changes:
{ seq: 27,
id: '3d75a794b4d0fe5d661444917b34bfda',
changes: [ { rev: '1-20c692ec75ac9135e40b74fb12028b11' } ] }
save_seq = 0
processed_seq does not exist
processed_seq does not exist
processed_seq does not exist
created state document
saved seq = 2
created state document
saved seq = 5
created state document
saved seq = 27

aber der schickt doch wat ...

127.000.000.001.33982-127.000.000.001.05984: PUT /simpledoc_development/_state? HTTP/1.1
host: localhost
Content-Length: 20
Content-Type: application/json
Connection: close

{"processed_seq":27}