maXbox Starter 40 REST API Coding

maXbox Starter 40
Start with REST API Coding
1.1 Go with OpenWeatherMap
So what is REST? REST (REpresentational State Transfer) is a simple
stateless architecture concept that generally runs over HTTPS/TLS. The
REST style emphasizes that interactions between clients and services are
enhanced by having a limited number of operations, most of them is GET.
Flexibility and simplification is provided by assigning resources just their
own unique universal resource indicators (URIs).
Now with a few lines of code we build a weather station, just the call:
writeln(GetGeoWeather('Bern', UrlWeatherReport25));
This RestFul Weather1
API provides the weather state for a given location,
specified by name or code. This service can be accessed using either REST
or SOAP calls in XML or Jason format.
You can interact with the REST service by visiting the following URLs:
api.openweathermap.org/data/2.5/weather?q={city name}
You can access current weather data for any location on Earth including
over 200,000 cities! Current weather is frequently updated based on
global models and data from more than 40,000 weather stations. Data is
available in JSON, XML, or HTML format.
First I define a Const:
Const
UrlWeatherReport25=
'http://api.openweathermap.org/data/2.5/weather?q=%s&units=metric';
1
You find also REST for Weather Forecasting

You can see the version 2.5 in const name and a metric parameter which
holds celcius instead of kelvin temperature is added.
Version information is an important thing cause we are dependent from
the service providers updates and if something doesn't goes right then go
left (just kidding).
Indeed the version information keeps your interface stable and improves
the way to find errors, downtimes or bugs. Most of webmasters want to
display weather information on their website. So I have decided to provide
this tutorial to do this via maXbox or PHP script.
The OpenWeatherMap service provides free weather data and forecast API
suitable for any cartographic services like web and smartphones
applications, also forecasting is possible.
http://api.openweathermap.org/data/2.5/forecast/daily?
id=524901&lang={lang}
Ideology is inspired by OpenStreetMap and Wikipedia that make
information free and available for everybody but as said dependent.
http://superdevresources.com/weather-forecast-api-for-developing-apps/
For example we are dependent of the availability and should consider
most of messages a provider delivers:
“The Nominatim Search Service will be unavailable on Tuesday, August 18, 2015
due to system maintenance. While it is never our intention to cause service
disruptions, the outage is necessary. We apologize for the inconvenience that this
will cause to our users of Nominatim”.
As I said you can interact with most of the REST services by visiting the
URLs and made some tests, below more URLs:
2

Const
UrlMapQuestAPICode2='http://open.mapquestapi.com/nominatim/v1/search.php?format=
%s&json_callback=renderBasicSearchNarrative&q=%s';
UrlMapQuestAPIReverse= 'http://open.mapquestapi.com/nominatim/v1/reverse.php?
format=%s&json_callback=renderExampleThreeResults&lat=%s&lon=%s';
UrlGeoLookupInfo2 ='http://ipinfodb.com/ip_query.php?timezone=true&ip=%s';
UrlGeoLookupInfo3 = 'http://api.hostip.info/get_html.php?ip=%s&position=true';
Now we jump to the code behind the URL, which is a GET command as a
function to fill a stream with the requested data:
function GetGeoWeather(const location: string;
const UrlRestAPI: string): string;
var lHTTP: TIdHTTP;
lStream: TStringStream;
begin
lHTTP:= TIdHTTP.Create(NIL);
lStream:= TStringStream.Create('');
try
try
lHTTP.Get1(Format(UrlRestAPI,[location]),lStream);
except
lHTTP.Get1(Format(UrlGeoLookupInfo2,[location]),lStream);
//if something wrong try using a backup server.
end;
lStream.Seek(0,0);
result:= 'GEO_Weather_Report: '+lStream.ReadString(lStream.Size);
finally
lHTTP.Free;
lStream.Free;
end;
end;
Call then current weather data for one location by city name or other
parameters like this:
//writeln(GetGeoWeather('krumpendorf', UrlWeatherReport25));
writeln(GetGeoWeather('bern', UrlWeatherReport25));
writeln(GetGeoWeather('cologne', UrlWeatherReport25));
Cologne is an interesting thing cause it delivers a weather report from an
Italian city so it seems the English name of Köln has a name conflict. So I
recommend to call API by city ID to get unambiguous result for your city.
Then I checked with “koeln” and its right now:
GEO_Weather_Report: {"coord":{"lon":6.95,"lat":50.93},
3

Description: You can call by city name or city name and country code. API
responds with a list of results that match a searching word, in our example
a not so well color-formatted json format:
GEO_IP Out: Country: SWITZERLAND (CH)
City: Bern
Latitude: 46.9167
Longitude: 7.4667
GEO_Weather_Report: {"coord":{"lon":7.45,"lat":46.95},"weather":
[{"id":803,"main":"Clouds","description":"broken clouds","icon":"04d"}],"base":"cmc
stations","main":
{"temp":19.27,"pressure":1014,"humidity":68,"temp_min":15.56,"temp_max":23.89},"wind":
{"speed":1.5,"deg":20.506},"clouds":{"all":75},"dt":1439805254,"sys":
{"type":1,"id":6013,"message":0.0048,"country":"CH","sunrise":1439785803,"sunset":143983
6653},"id":2661552,"name":"Bern","cod":200}
### mX3 executed: 17.08.2015 12:07:08 Runtime: 0:0:11.370
Memload: 78% use
If you do not see some of the parameters in your API respond it means
that these weather phenomena are just not happened for the time of
measurement for the city or location chosen. Only really measured or
calculated data is displayed in API respond.
Both types of calls are also aimed at WSDL endpoints if needed and can
produce different output in different formats.
If you can’t find the two files try also direct as a file or at sourceforge:
http://www.softwareschule.ch/examples/640_rest_weather_report.txt
http://www.softwareschule.ch/examples/640_rest_geocode.txt
Next you find an output of a weather data combined with an XML Map as a
preparation for next chapter:
<?xml version="1.0" encoding="UTF-8"?>
-<searchresults more_url="http://mq-open-search-ext-
la02.ihost.aol.com:8000/nominatim/v1/search?
format=xml&exclude_place_ids=705429&q=krumpendorf+strandweg"
exclude_place_ids="705429" polygon="false" querystring="krumpendorf strandweg"
attribution="Data © OpenStreetMap contributors, ODbL 1.0.
http://www.openstreetmap.org/copyright" timestamp="Sun, 16 Aug 15 12:56:58 +0000">
<place icon="http://mq-open-search-ext-
la02.ihost.aol.com:8000/nominatim/v1/images/mapicons/transport_train_station2.p.20.png"
importance="0.201" type="station" class="railway" display_name="Krumpendorf, Strandweg,
Gemeinde Krumpendorf am Wörthersee, Klagenfurt-Land, Region Klagenfurt-Villach, Kärnten,
9201, Österreich" lon="14.2218479" lat="46.6264738"temperature="18.62"
boundingbox="46.6264738,46.6264738,14.2218479,14.2218479" place_rank="30"
osm_id="247629819" osm_type="node" place_id="705429"/>
</searchresults>
4

A last sample query string of a weather forecast follows:
http://graphical.weather.gov/xml/sample_products/browser_inter
face/ndfdXMLclient.php?listLatLon=38.99,-77.02 39.70,-104.80
47.6,-122.30&product=time-series&begin=2004-01-
01T00:00:00&end=2013-04-20T00:00:00&Unit=e&maxt=maxt&mint=mint
The NDFD data available via the REST service is updated no more than
hourly. As a result, we request developers using this REST service only
make a request for a specific point no more than once an hour.
The database is currently updated by 45 minutes after the hour.
1.2 The Weather with Maps
One of the questions that comes up when encoding those coordinates is
how they can be useful in a script with for example in maXbox:
OpenMapX('cathedral cologne');
OpenMapX('50.94134 6.95813'); //string!
With a GPS or navigation: The Global Positioning System (GPS) is a space-
based satellite navigation system that provides location and time
information in all weather conditions. But you need a map to visualize.
 Each GPS satellite continuously broadcasts a navigation message at a
rate of 50 bits per second. A message takes 750 seconds to complete!
Such a record does have as minimum navi information:
procedure GPSRecord
begin
writeln('time,date,latitude,longitude,altitude,nsat,speed,course');
end
This isn't very different from a normal weather station clock, isn't it? Now
we define our map search to get the map in your standard browser. We
use the mapquest API from:
http://open.mapquestapi.com/nominatim/
As many of you know, MapQuest hosts a version of the Nominatim Search
Service as a part of our Open Data API and SDK product line, so we wanted
to share an important update about this service that will have an impact
on users of this service.
The following example demonstrates a simple map search request for
“Cathedral Cologne“ using the Nominatim quest. Only three parameters
are being requested (menu: ViewGEO Map View):
5

1. format - Output format being called. [html/json/xml]
2. json_callback - Callback function used to display results below.
3. q - Query string being searched for.
We set first a const in the script to send the request:
Const
AMAPFILENAME2= 'maxmapfile.html';
UrlMapQuestAPICode2='http://open.mapquestapi.com/nominatim/v1/search
.php?format=%s&json_callback=renderBasicSearchNarrative&q=%s';
How are these 3 arguments linked together:
• format=%s
• json_callback=renderBasicSearchNarrative
• q=%s
You'll notice that the json_callback parameter is already set. The format
and the query string indeed is up to you. We use a html format to prepare
open a browser with the map, se here's the call:
if GetMAPX('html',ExePath+'cologne2mapX.html','cathedral cologne')
then writeln('Cologne Map found');
By the way: Most of GPS and data formats is found by the NMEA.
The NMEA is the National Marine Electronics Association. It is to be a
worldwide, self-sustaining organization committed to enhancing the
technology and safety of electronics used in marine applications and you
see also a standard for GPS data formats.
How it works: The GPS satellites transmit signals to a GPS receiver. These
receivers passively receive those signals; they do not transmit and require
a clear view of the sky, so they can only be used effectively outdoors, or
from time to time in trains or gadgets;-).
Type
TReceive_Func = TGPS.SerialRxChar(Sender: TObject);
Lets back to our easy call
6

GetMAPX('html',ExePath+'cologne2mapX.html','cathedral cologne')
OpenMap('ubs ag burgdorf');
You also find a procedure with same meaning
GetGeoMAP('html',ExePath+AMAPFILENAME2,'dom cologne')
Note: in both cases, this code is assuming D2007 or earlier as maXbox
follows. In D2009 and later, String is Unicode now, so you need to know
the Encoding of the TStream contents ahead of time in order for the bytes
to be interpretted as, or converted to, Unicode correctly.
Otherwise, you would have to change to operate on AnsiString or the new
RawByteString instead.
1.2.1 The Dark side of the Code
Obviously the most important device required for this software to work, is
the map from the internet provider OpenStreetMap. All browser devices with
a Java Script ECMA compatible connection are supported.
The Java Script code which sends the request and displays the result can
be viewed here as an XML output for example:
Test mX4 Ref: XML, JSON, HTML
<reversegeocode timestamp="Thu, 12 Sep 14 20:52:32 +0000" attribution="Data
© OpenStreetMap contributors, ODbL 1.0.
http://www.openstreetmap.org/copyright"
querystring="format=html&json_callback=renderExampleThreeResults&lat=47.039
7826&lon=7.62914761277888"><result place_id="15120759" osm_type="node"
osm_id="1378799522" ref="UBS AG" lat="47.0398676" lon="7.6291424">UBS AG,
Bahnhofstrasse, Oberstadt, Burgdorf, Verwaltungskreis Emmental,
Verwaltungsregion Emmental-Oberaargau, Bern, 3414,
Switzerland</result><addressparts><atm>UBS
AG</atm><road>Bahnhofstrasse</road><neighbourhood>Oberstadt</neighbourhood>
<town>Burgdorf</town><county>Verwaltungskreis
Emmental</county><state_district>Verwaltungsregion Emmental-
Oberaargau</state_district><state>Bern</state><postcode>3414</postcode><cou
ntry>Switzerland</country><country_code>ch</country_code>
</addressparts></reversegeocode>
From the result let's go back to the code behind.
As you already know the tool is split up into the toolbar across the top, the
editor or code part in the centre and the output window at the bottom.
Change that in the menu /view at our own style.
 Before this starter code will work you will need to download maXbox
from a website. You'll get it from
http://www.softwareschule.ch/maxbox.htm . Once the download has
finished, unzip the file, making sure that you preserve the folder structure
as it is. Test it with F9 / F2 or press Compile and you should hear a test
sound. So far so good now we’ll open the examples:
509_GEOMap3.txt
If you can’t find the two files try also direct as a file
http://www.softwareschule.ch/examples/509_GEOMap3.txt
7

Now let’s take a look at the code of this app. One of our first line is
creating the object mapStream and the encoded URL we use first methods
to configure our HTTPGet() calling Port and IP of the mapquest API with the
help of HTTPEncode. The object makes a bind connection with the Active
method by passing an encoded URL with a memory stream:
procedure GetMapScript(C_form,apath: string; const Data:string);
var encURL: string;
mapStream: TMemoryStream;
begin
encURL:= Format(UrlMapQuestAPICode2, [c_form,HTTPEncode(Data)]);
mapStream:= TMemoryStream.create;
try
HttpGet(EncURL, mapStream); //WinInet
mapStream.Position:= 0;
mapStream.Savetofile(apath)
OpenDoc(apath);
finally
mapStream.Free;
end;
end;
The OpenDoc() procedure is used in this context to get a rich browser
open, you remember the call above:
GetMAPScript('html',ExePath+'cologne2mapX.html',
'cathedral cologne')
As we decode this with Format like above:
• format=html
• json_callback=renderBasicSearchNarrative
• q=cathedral cologne
And this is how another function with download works:
function GetMapXScript(C_form,apath: string; const Data: string): boolean;
var encodedURL: string;
begin
encodedURL:= Format(UrlMapQuestAPICode2,[c_form,HTTPEncode(Data)]);
try
//instead HttpGet(EncodedURL, mapStream); //WinInet
Result:= UrlDownloadToFile(Nil,PChar(encodedURL),PChar(apath),0,Nil)= 0;
OpenDoc(apath);
finally
encodedURL:= '';
end;
end;
//ShellExecute3('http://maps.google.com/maps?
q=+50.94133705,+6.95812076100766','',seCMDOPen)
8

This function is shorter than the first one because we use no streams in
between. Working with streams in Free Pascal or Delphi you have to
include some units to be able to use or code your functions direct in the
script as you like:
function DownloadFile(SourceFile, DestFile: string): Boolean;
begin
//TCIPStatus TBindStatus TURLTemplate of URLMon
try
Result:=
UrlDownloadToFile(Nil,PChar(SourceFile),PChar(DestFile),0,Nil)= 0;
except
Result:= False;
end;
end;
In maXbox those units and many others are pre-compiled and included on
demand. As long as the API is stable we don't have change calls.
UrlMapQuestAPICode2='http://open.mapquestapi.com/nominatim/v1/search
.php?format=%s&json_callback=renderBasicSearchNarrative&q=%s';
After these steps, we can start with programming the rest of the GEO code
called reverse GEO code.
 Reverse geocoding is the process of back (reverse) coding of a point
location (latitude, longitude) to a readable address or place name.
GeoNames for ex. offers a wide range of reverse geocoding web services.
This permits identification of nearby street addresses, places, stations
and/or areal subdivisions such as county, state or country.
9

1.2.2 Reverse GEO Code
The interesting point is now that we store no data on a file we just use a
memory stream to get data direct on the console of maXbox.
Those data can be used with any console or script receiver to make further
investigations. This may however vary depending on what data sentence
the coordinates find or delivers, for ex. the cathedral at cologne:
writeln(GetMapXGeoReverse('XML','50.94134','6.95813'))
or more accurate:
GetMapXGeoReverse2('XML',topPath,'50.94133705','6.95812611100766')
then
<?xml version="1.0" encoding="UTF-8"?>
-<reversegeocode
querystring="format=XML&json_callback=renderExampleThreeResults&lat=50.9413
3705&lon=6.95812611100766" attribution="Data © OpenStreetMap contributors,
ODbL 1.0. http://www.openstreetmap.org/copyright" timestamp="Mon, 22 Sep 14
13:36:43 +0000">
<result lon="6.95812611100766" lat="50.94133705" ref="Kölner Dom"
osm_id="4532022" osm_type="way" place_id="40406499">Kölner Dom, 4,
Domkloster, Ursula-Viertel, Altstadt-Nord, Innenstadt, Köln,
Regierungsbezirk Köln, Nordrhein-Westfalen, 50667,
Deutschland</result>-
<addressparts>
<place_of_worship>Kölner Dom</place_of_worship>
<house_number>4</house_number>
<pedestrian>Domkloster</pedestrian>
<neighbourhood>Ursula-Viertel</neighbourhood>
<suburb>Altstadt-Nord</suburb>
<city_district>Innenstadt</city_district>
<county>Köln</county>
<state_district>Regierungsbezirk Köln</state_district>
<state>Nordrhein-Westfalen</state>
<postcode>50667</postcode>
<country>Deutschland</country>
<country_code>de</country_code>
</addressparts>
</reversegeocode>
Reverse geocoding can be carried out systematically by services which
process a coordinate similarly to a geocoding process.
For ex., when a GPS coordinate is entered the street address is interpol-
ated from a range assigned to the road segment in a reference dataset
that the point is nearest to.
osm_id="4532022" osm_type="way" place_id="40406499">Kölner Dom, 4,
Domkloster, Ursula-Viertel, Altstadt-Nord, Innenstadt, Köln,
Regierungsbezirk Köln, Nordrhein-Westfalen, 50667,
Deutschland</result>-
Each table has a way column containing the geometry for the object in
the chosen projection. Two indices are created for each table: one for the
way column and one for the osm_id column, see above.
10

Geometry uses coordinates in the EPSG:900913 AKA G00GlE projection
and can be easily used in e.g. OpenLayers based JavaScript.
Now for the code behind the call. We need another mapquest API of the get
request service:
UrlMapQuestAPI3:= 'http://open.mapquestapi.com/nominatim/v1/reverse.php?
As you can see it's a PHP server side service:
encodedURL:
http://open.mapquestapi.com/nominatim/v1/reverse.php?
The function maps a stream to a string and is similar to above, except we
don't save a file, but you can save the stream as an XML or Json file:
mapstream.savetofile(apath) and OpenDoc(apath);
function GetMapXGeoReverse2(C_form,apath: string; const lat,long:
string):boolean;
var encodedURL, UrlMapQuestAPI, bufstr: string;
mapStream: TMemoryStream;
begin
UrlMapQuestAPI:= 'http://open.mapquestapi.com/nominatim/v1/reverse.php?
encodedURL:= Format(UrlMapQuestAPI,[c_form, lat, long]);
mapStream:= TMemoryStream.create;
try
HttpGet(EncodedURL, mapStream); {WinInet}
mapStream.Position:= 0;
writeln('stream size: '+inttostr(mapstream.size)); //mapStream.memory;
bufstr:= StreamToString(mapstream);
writeln('stream back: '+bufstr)
finally
encodedURL:= '';
mapStream.Free;
end;
end;
Two ways to map a stream to a string:
1. Read the available Size of the TStream, allocate a String of that length,
and then Read() the TStream contents into the String:
function StreamToString2(Stream: TStream): String;
var
len: Integer;
begin
len:= Stream.Size - Stream.Position;
SetLength(Result, len);
if len > 0 then Stream.ReadBuffer(Result, len);
writeln('test - buffer read check!')
end;
11

2. Create an intermediate TStringStream, CopyFrom() the TStream to the
TStringStream, and then read the TStringStream.DataString property:
{code:maXbox}
function StreamToString3(Stream: TStream): String;
begin
with TStringStream.Create('') do
try
CopyFrom(Stream, Stream.Size-Stream.Position);
Result:= DataString;
finally
Free;
end;
end;
 TMemoryStream and TFileStream are both decendants of TStream and
they work exactly the same way.
The problem I mostly found is that if we write one stream to another, we
have to reset the origins before using it again like
(MS.Seek(0,soFromBeginning);.
Another point is to direct test a pair of coordinates. You can also convert
coordinates (lat and long) to a map on the internet (Appendix).
http://www.gps-coordinates.net/
You can find the address corresponding to GPS coordinates or latitude,
longitude and address of any point on OpenStreetMap.
Hope you did already work with the Starter 34 on GPS topics:
http://sourceforge.net/p/maxbox/wikimax/main/
At least we see a picture over a distance of 388 km. This image below is
my sight of a track: the yellow line is the speed and the blue one marks
the altitude point.
12

Almanac data is data that describes the orbital courses of the satellites.
Every satellite will broadcast almanac data for EVERY satellite. Your GPS
receiver uses this data to determine which satellites it expects to see in
the local sky; then it can determine which satellites it should track.
1.3 GPS and Arduino Conclusion
I would also recommend the book “Arduino Cookbook” by Michael
Margolis. Here are a few ideas of more complicated projects that I have
seen made with an Arduino.
• A box that will only open when it is at a certain location in the world (It
connects a GPS to the Arduino. Search on “Reverse Geo-cache” to see
some examples.)
• Or a controller for a 3D printer to print out the landscape the GPS or
OpenMAPX() has just scanned!
Feedback @
max@kleiner.com
Literature: Kleiner et al., Patterns konkret, 2003, Software & Support
www.openweathermap.com
http://en.wikipedia.org/wiki/Reverse_geocoding
http://www.kleiner.ch/kleiner/gpsmax.htm
http://www.softwareschule.ch/examples/475_GPS_mX2.txt
Stream Ref:
http://embarcadero.newsgroups.archived.at/public.delphi.vcl.components.usin
g/200907/0907292775.html
• Arduino Example.
http://www.softwareschule.ch/download/Arduino_C_2014_6_basta_box.pdf
http://sourceforge.net/projects/maxbox
13

1.4 Appendix Map Study
maXmap
DD (decimal degrees)*
Latitude 48.725447N (48.656280963566495)
Longitude 7.143274E (6.991813648492098)
1 Rue du Canal, 57405 Guntzviller, France
Latitude : 48.725447 | Longitude : 7.143274 Altitude : 287 meters
Here another map search zoom of OpenMAPX:
RTClock: Arduino by Silvia Rothen http://www.ecotronics.ch/ecotron/arduinocheatsheet.htm
14

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