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tile38

Node driver for Tile38

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Tile38 Node driver

This library can be used to access the Tile38 server from Node.js apps.

Links

Installation

npm install tile38

Overview

While you can use your preferred Redis library to communicate with the Tile38 geolocation database, this node library offers a much more pleasant query interface for all Tile38 commands. It also supports live geofencing using persistent sockets to the server.

In most cases, commands follow the command documentation on the Tile38 website, though the search/scan commands use method chaining. You can find some examples below as well as in the examples folder.

This library has not been tested in the browser. You generally would not want to expose your database directly to the internet, and you also don't want to share Tile38 access credentials to a web client, so using this in the browser is not a good idea.

Revision history

See the CHANGELOG

Connection

var Tile38 = require('tile38');
var client = new Tile38();
// save a location
client.set('fleet', 'truck1', [33.5123, -112.2693]);
// save a location with additional fields
client.set('fleet', 'truck2', [33.5123, -112.2693], { value: 10, othervalue: 20});

You can pass any non-default connection settings into the Tile38 constructor, and you can also turn on optional debug logging as illustrated below.

var client = new Tile38({host: 'host.server.com', port: 9850, debug: true });

You can also set the hostname, port and password using the environment vars TILE38_HOST, TILE38_PORT and TILE38_PASSWD. These environment variables will only be used if values are not passed into the constructor explicitly

Custom logger

This driver does not use a logging library, and logs messages to the console by default. However, you may pass a custom log implementation into the constructor. Your custom logger must implement the 'log', 'warn' and 'error' functions, all accepting strings.

const customLogger = {
  log:   function(msg) { ... },
  warn:  function(msg) { ... },
  error: function(msg) { ... }
}
const client = new Tile38({debug: true, logger: customLogger });

Promises

All of the implemented methods return promises (with the exception of executeFence(), see more info on that below).

client.get('fleet', 'truck1').then(data => {
  console.log(data); // prints coordinates in geoJSON format

}).catch(err =>
  console.log(err); // id not found  
});

// return the data as type POINT, and include FIELDS as well.  
client.get('fleet', 'truck2', {type: 'POINT', withfields: true}).then(data => {
  console.log(`truck2 is at ${data.point.lat},${data.point.lon}`);
  console.dir(data.fields);
});
// There's also a getPoint(id,key) method that can be used as a shortcut instead of get(id,key,{type:'POINT'})
// as well as similar getBounds and getHash methods.

Many commands may not return values, but they still return promises, allowing you to wait until your changes have been persisted.

client.set('fleet', 'truck1', [33.5123, -112.2693]).then(() => {
  console.log('your changes have been persisted');
});

You may, of course, prefer to use async/await instead of Promises, like so:

let data = await client.getPoint('fleet', 'truck2');
console.log(`truck2 is at ${data.point.lat},${data.point.lon}`);

Command examples

The command documentation for Tile38 server is followed as closely as possible. Command names become function names, mandatory properties become arguments, and optional properties become either optional arguments or are passed in through an options object argument.

For example, the command

JGET key id path

is called as follows:

client.jget(key, id, path)

keys commands

Some examples of keys commands:

client.bounds('fleet');
client.del('feet', 'truck2');
client.drop('fleet');
client.expire('fleet','truck', 10);
client.fset('fleet', 'truck1', 'speed', 16);
client.fset('fleet', 'truck1', {speed: 16, driver: 1224});
client.stats('fleet1', 'fleet2');
...etc

get command

The get command accepts an optional object that can be use to set the response data type:

// return truck1 location as a geoJSON object
client.get('fleet', 'truck1');
client.get('fleet', 'truck1', { type: 'OBJECT' });   // equivalent
// return as POINT (2 element array with lat/lon coordinates)
client.get('fleet', 'truck1', { type: 'POINT' });
client.getPoint('fleet', 'truck1');   // equivalent of above
// return bounding rectangle
client.get('fleet', 'truck1', { type: 'BOUNDS' });
client.getBounds('fleet', 'truck1');   // equivalent of above
// return a geohash with precision 6 (must be between 1 and 22)
client.get('fleet', 'truck1', { type: 'HASH 6' });
client.getHash('fleet', 'truck1');   // equivalent of above
client.getHash('fleet', 'truck1', { precision: 8});   // if you need different precision from default (6)

// if you want the 'get' function to return fields as well, use the 'withfields' property
client.get('fleet', 'truck1', { withfields: true });

set command

The set command has various forms.

set(key, id, locationObject, fields, options)

// set a simple lat/lng coordinate
client.set('fleet', 'truck1', [33.5123, -112.2693])
// set with additional fields
client.set('fleet', 'truck1', [33.5123, -112.2693], { field1: 10, field2: 20});
// set lat/lon/alt coordinates, and expire in 120 secs
client.set('fleet', 'truck1', [33.5123, -112.2693, 120.0], null, {expire: 120})
// set bounds
set('props', 'house1', [33.7840, -112.1520, 33.7848, -112.1512])
// set an ID by geohash
set('props', 'area1', '9tbnwg')   // assumes HASH by default if only one extra parameter
// set a String value
set('props', 'area2', 'my string value', null, {type: 'string'}) # or force to String type
// set with geoJson object
set('cities', 'tempe', geoJsonObject)
// only set truck1 if it doesn't exist yet
client.set('fleet', 'truck1', [33.5123, -112.2693], null, {onlyIfNotExists: true})

search commands

The search commands use method chaining to deal with its many available options. See the query examples below, or look at tile38_query.js to see all available methods.

One time results vs live geofence

To execute the query and get the search results, use the execute() function, which will return a promise to the results.

let query = client.intersectsQuery('fleet').bounds(33.462, -112.268, 33.491, -112.245);
query.execute().then(results => {
    console.dir(results);  // results is an object.
}).catch(err => {
    console.error("something went wrong! " + err);
)};

To set up a live geofence that will use a websocket to continuously send updates, you construct your query the exact same way. However, instead of execute() (which returns a Promise), use the executeFence() function while passing in a callback function.

let query = client.intersectsQuery('fleet').detect('enter','exit').bounds(33.462, -112.268, 33.491, -112.245);
let fence = query.executeFence((err, results) => {
    // this callback will be called multiple times
    if (err) {
        console.error("something went wrong! " + err);
    } else {
        console.dir(results);
    }
});

// if you want to be notified when the connection gets closed, register a callback function with onClose()
fence.onClose(() => {
    console.log("geofence was closed");
});

// later on, when you want to close the socket and kill the live geofence:
fence.close();

Many of the chaining functions below can be used for all search commands. See the Tile38 documentation for more info on what query criteria are supported by what commands.

Do not forget to call the execute() or executeFence() function after constructing your query chain. I've left this out in the examples below for brevity.

INTERSECTS

// basic query that uses bounds
client.intersectsQuery('fleet').bounds(33.462, -112.268, 33.491 -112.245)
// intersect with a circle of 1000 meter radius
client.intersectsQuery('fleet').circle(33.462, -112.268, 1000)
// using cursor and limit for pagination
client.intersectsQuery('fleet').cursor(100).limit(50).bounds(33.462, -112.268, 33.491 -112.245)
// create a fence that triggeres when entering a polygon
let polygon = {"type":"Polygon","coordinates": [[[-111.9787,33.4411],[-111.8902,33.4377],[-111.8950,33.2892],[-111.9739,33.2932],[-111.9787,33.4411]]]};
client.intersectsQuery('fleet').detect('enter','exit').object(polygon)

// basic search query
client.searchQuery('names')
// use matching patter and return results in descending order, without fields
client.searchQuery('names').match('J*').nofields().desc()
// return only IDs
client.searchQuery('names').output('ids')
// this does the same:
client.searchQuery('names').ids()
// return only count
client.searchQuery('names').count()
// use the where option
client.searchQuery('names').where('age', 40, '+inf')

NEARBY

// basic nearby query, including distance for each returned object
client.nearbyQuery('fleet').distance().point(33.462, -112.268, 6000)
// return results as geohashes with precision 8
client.nearbyQuery('fleet').point(33.462, -112.268, 6000).hashes(8)
// use the roam option
client.nearbyQuery('fleet').roam('truck', 'ptn', 3000)
client.nearbyQuery('fleet').nodwell().roam('truck', 'ptn', 3000)  // with NODWELL option
// use the whereeval option. (unlike the Tile38 CLI no need to specify the number of arguments).
// You may also call whereEval (or whereEvalSha) multiple times in your command chain.
client.nearbyQuery('fleet').whereEval("return FIELDS.wheels > ARGV[1] or (FIELDS.length * FIELDS.width) > ARGV[2]", 8, 120);

SCAN

// basic scan query, returning all results in geojson
client.scanQuery('fleet').output('objects');
// this does the same
client.scanQuery('fleet').objects()
// return simple coordinates, and do not include fields
client.scanQuery('fleet').nofields().points()

WITHIN

The withinQuery has the same query options as intersects.

// basic within query, returning all results in geojson
client.withinQuery('fleet').bounds(33.462, -112.268, 33.491, -112.245)
// check within an area that's already defined in the database
client.withinQuery('fleet').get('cities', 'tempe')
// return objects within a given tile x, y, z
client.withinQuery('fleet').tile(x, y, z);
// return objects within a given circle of 1000 meter radius
client.withinQuery('fleet').circle(33.462, -112.268, 1000)

using timeouts

The scan/search commands above can be used with a timeout as well, so the command will be aborted if a given timeout is exceeded. The timeout function can be called after the initial query is created (with searchQuery/nearbyQuery etc.) as follows:

client.scanQuery('mykey').where('foo', 1, 2).count().timeout(0.1);

Unsupported commands

It's hard to keep up with development and new features in Tile38. The following commands are not yet supported in this driver. Pull requests welcome:

All channel commands (CHANS, DELCHAN, PDELCHAN, PSUBSCRIBE, SETCHAN, SUBSCRIBE) \ HEALTHZ \ JGET does not support the RAW option \ JSET does not support the RAW or STR options \ All replication commands (AOF, AOFMD5, AOFSHRINK, FOLLOW) \ All scripting commands (EVAL, EVALNA, EVALNASHA, EVALRO, EVALROSHA, EVALSHA, SCRIPT EXISTS, SCRIPT FLUSH, SCRIPT LOAD) \ #TODO need to review what else is incomplete.

Note that even unsupported commands can be called through this library as follows:

let success = await client.executeCommand('SCRIPT LOAD MYSCRIPT');

Using executeCommand you can send any command exactly as documented in the Tile38 command docs. Most Tile38 commands return a json response with an ok=true property. By default, executeCommand will parse and return (a promise to) the value of this 'ok' property and thus return a boolean true.

To parse and return a different object from the Tile38 JSON response:

let keys = await client.executeCommand('KEYS *', { returnProp: 'keys'})

or to skip JSON parsing altogether and return the raw server response

let rawResponse = client.executeCommand('KEYS *', { parseJson: false })

Note that if the server returns ok=false in any response, this library will reject the Promise. The only exception to this is if you set the parseJson=false property as illustrated above, in which case it will not try to interpret the response in any way.

Running tests

WARNING: THIS WILL WIPE OUT YOUR DATA! The test suite currently depends on having a local instance of Tile38 running on the default port 9851. It tests all supported commands, including FLUSHDB, so you'll LOSE ALL EXISTING DATA in your Tile38 instance.

To change the Tile38 host name, port number, or configure authentication password, set the TILE38_HOST, TILE38_PORT and/or TILE38_PASSWD environment variables before running the tests.

If you have nothing critical in your local db, you can run the tests with:

npm test

Project roadmap

Other potential shortcomings and/or future improvements beyond adding above mentioned commands:

  • The executeFence method / live geofences has had limited testing. Please submit bugs if you run into issues.
  • The SETHOOK command has some similarities to the search commands. It's not currently using method chaining but I may rewrite it so it can be used in a similar way to the other search functions.

Testing TODO:

  • webhooks needs test coverage
  • test coverage for live geofences

Missing something? Did it break?

For bugs or feature requests, please open an issue.

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