"use strict";
var _ = require('underscore');
var fs = require('fs');
var Rollbar = require('rollbar');
var WindshaftServer = require('./http/windshaftServer.js');
var healthCheck = require('./healthCheck');
var makeSql = require('./makeSql');
var config = require('./config');Optional environment variable for reporting exceptions to rollbar.com
var rollbarAccessToken = process.env.ROLLBAR_SERVER_SIDE_ACCESS_TOKEN;
if (rollbarAccessToken) {
var rollbar = new Rollbar({
accessToken: rollbarAccessToken,
environment: process.env.OTM_STACK_TYPE || 'Unknown'
});
}
var dbname = process.env.OTM_DB_NAME || 'otm';
var port = process.env.PORT || 4000;
var ws;
var styles = {
boundary: fs.readFileSync('style/boundary.mms', {encoding: 'utf-8'}),
canopy: fs.readFileSync('style/canopy.mms', {encoding: 'utf-8'}),
mapFeature: fs.readFileSync('style/mapFeature.mms', {encoding: 'utf-8'}),
uncoloredMapFeature: fs.readFileSync('style/uncoloredMapFeature.mms', {encoding: 'utf-8'}),
polygonalMapFeature: fs.readFileSync('style/polygonalMapFeature.mms', {encoding: 'utf-8'})
};
function parseBoundaryCategory(category) {
if (/^[A-Za-z0-9 ]+$/.test(category)) {
return category;
}
return undefined;
}Configure the Windshaft tile server to handle OTM’s HTTP requests, which retrieve e.g. a map tile or UTF grid with map features like tree plots or boundaries.
var windshaftConfig = {
useProfiler: false, // if true, returns X-Tiler-Profiler header with rendering times
enable_cors: true,
log_format: null,
mapnik: {When looking for objects to render on a tile, mapnik by default adds 64 pixels on all sides of a tile so if e.g. a label spans two tiles it will be rendered on both rather than getting cut off at the boundary. Because we’re only rendering tree dots we can reduce the buffer based on our biggest dot. This speeds up rendering by as much as 25%.
bufferSize: Math.floor(config.treeMarkerMaxWidth / 2) + 1,Metatiles aren’t a good fit for rendering tree dots using multiple servers and workers. When you request a 256x256 tile, mapnik renders by default a 1024x1024 metatile, and caches the resulting 16 tiles. They’re aiming at basemaps, where for example if a road segment crosses three tiles it’s more efficient to render it once than three times since you’ll often want all 3 tiles. That’s a bad fit for OTM for two reasons. First, our tree dots are less likely to span multiple tiles. Second, since metatiles aren’t shared across servers or even across workers on the same server, our AWS tiler setup (currently two tile servers with two workers each) is likely to render each metatile multiple times, making things slower rather than faster.
metatile: 1
},
redis: {
host: process.env.OTM_CACHE_HOST || '127.0.0.1',
port: process.env.OTM_CACHE_PORT || 6379
},How to access the database
grainstore: {
datasource: {
user: process.env.OTM_DB_USER || 'otm',
password: process.env.OTM_DB_PASSWORD || 'otm',
host: process.env.OTM_DB_HOST || 'localhost',
port: process.env.OTM_DB_PORT || 5432
}
}, // See grainstore npm for other optionsParse params from the request URL The parameter after database is unused, but left in for legacy reasons so that older versions of the mobile apps will be able to continue to make tile requests
base_url: '/:cache_buster/database/:unused/table/:table',Tell server how to handle HTTP request ‘req’ (by specifying properties in req.params).
req2params: function(req, callback) {
var instanceid, isUtfGridRequest, isPolygonRequest, table,
zoom, filterString, displayString, restrictFeatureString;Specify SQL subquery to extract desired features from desired DB layer. (This will be wrapped in an outer query, in many cases extracting geometry using the magic column name “the_geom_webmercator”.)
try {
instanceid = parseInt(req.query.instance_id, 10);
table = req.params.table;
zoom = req.params.z;
isPolygonRequest = (table === 'stormwater_polygonalmapfeature');
if (table === 'treemap_mapfeature' || isPolygonRequest) {
filterString = req.query[config.filterQueryArgumentName];
displayString = req.query[config.displayQueryArgumentName];
restrictFeatureString = req.query[config.restrictFeatureQueryArgumentName];
isUtfGridRequest = (req.params.format === 'grid.json');
req.params.sql = makeSql.makeSqlForMapFeatures(filterString,
displayString,
restrictFeatureString,
instanceid,
zoom,
isUtfGridRequest,
isPolygonRequest,
req.instanceConfig);
if (isPolygonRequest) {
req.params.style = styles.polygonalMapFeature;
} else if (isUtfGridRequest) {
req.params.style = styles.uncoloredMapFeature;
} else {
req.params.style = styles.mapFeature;
}
} else if (table === 'treemap_boundary' && instanceid) {
req.params.sql = makeSql.makeSqlForBoundaries(instanceid);
req.params.style = styles.boundary;
} else if (table === 'treemap_canopy_boundary' && instanceid) {
var canopyMin = parseFloat(req.query.canopyMin),
canopyMax = parseFloat(req.query.canopyMax),
category = parseBoundaryCategory(req.query.category);
if (!category) {
throw new Error('Invalid argument: category');
}
if (isNaN(canopyMin) || !isFinite(canopyMin)) {
throw new Error('Invalid argument: canopyMin');
}
if (isNaN(canopyMax) || !isFinite(canopyMax)) {
throw new Error('Invalid argument: canopyMax');
}
req.params.sql = makeSql.makeSqlForCanopyBoundaries(instanceid,
canopyMin, canopyMax, category);
req.params.style = styles.canopy;
}
} catch (err) {
if (rollbarAccessToken) {
rollbar.error(err, req);
}
callback(err, null);
}A UTF grid request returns map feature data for each pixel in a tile, streamlining client actions like clicking on or hovering over a feature. “interactivity” specifies which fields from our SQL query should be returned for each feature.
req.params.interactivity = (isUtfGridRequest ? config.interactivityForUtfGridRequests : null);
req.params.dbname = dbname;Send the finished req object on
callback(null, req);
},
afterTileRender: function(req, res, tile, headers, callback) {
headers['Cache-Control'] = 'max-age=2592000';
callback(null, tile, headers);
}
};
ws = new WindshaftServer(windshaftConfig);
ws.get('/health-check', healthCheck(windshaftConfig));If a rollbar API token was provided this will wire up the rollbar error handler
if (rollbarAccessToken) {
ws.use(rollbar.errorHandler());
}
ws.listen(port);
console.log("Map tiles will be served from http://localhost:" + port + windshaftConfig.base_url + '/:zoom/:x/:y');