Android Question Exception with OkHttpUtils2

[Wosl]

Dear All!

I need some guidance ...

What I want to do:

geocoding of a given postal address which results in details like GPS coordinates

A simplified version of my App is as following:

Sub Activity_Create(FirstTime As Boolean)
    Private cAddress As String ="10117 Berlin, Pariser Platz 5"

    Log ("Address: " & cAddress)   
    Wait for (Geocoding(cAddress)) Complete(Result As Int)
    Log ("Return Code: " & Result)

End Sub
Sub Geocoding(aquery As String) As ResumableSub
    '#####################################################################
    '
    '  Geocoding a specific postal address (PLZ Stadt, Straße Hausnummer)
    '
    '  aquery        String with postal address
    '
    '#####################################################################
    Dim su As StringUtils
    Dim q As String=su.EncodeUrl(aquery,"UTF8")
    Dim s As String=$"https://nominatim.openstreetmap.org/?addressdetails=1&q=${q}&format=json"$
    Dim j As HttpJob
    Dim ier As Int

    Log ("Geocoding Query = '" & s & "'")
    Try
        j.Initialize("Geocoding", Me)
        j.Download(s)
        Wait For (j) JobDone(j As HttpJob)
        If j.Success Then
            Log ("Geocoding successfully done")
            Log ("Result = '" & j.GetString & "'")
            '
            ' ... parse for the GPS coordinates
            '
            ier = 0
        Else
            Log ("Geocoding failed (#1)")
            ier = 1
        End If
    Catch
        Log ("Geocoding failed (#2): " & LastException.Message)
        ier = 2
    End Try

    If j.IsInitialized Then    j.Release

    Return ier
End Sub

With that I receive following messages in the log:

** Activity (main) Create (first time) **
Address: 10117 Berlin, Pariser Platz 5
Geocoding Query = 'https://nominatim.openstreetmap.org/?addressdetails=1&q=10117+Berlin%2C+Pariser+Platz+5&format=json'
** Activity (main) Resume **
*** Receiver (httputils2service) Receive (first time) ***
ResponseError. Reason: , Response: Access denied. See https://operations.osmfoundation.org/policies/nominatim/
Geocoding failed (#1)
Return Code: 1
** Activity (main) Pause, UserClosed = false **

I did some variations (example: w/ and w/o try/catch - structures) which results some times in a different exception:
(ErrnoException) android.system.ErrnoException: open failed: ENOENT (No such file or directory)

When I type in the query into a browser I receive the excepted result.

It seams to me that the query result should be written to a place on my phone where I don't have access to.

What is wrong with my code?

Android version: 14
Smartphone: Galaxy A16 5G
B4A Version: 13.10

Any help appreciated ...
Wosl

PS: I use a similar code in an older android version ... and it worked. When I compile it on a newer Android version it fails.

 

[drgottjr]

read the response error. follow the link. do what it says: add user-agent and referer headers to your rquest. it's a recent change in osm's conditions of use. (note: it's also the case if you're accessing osm's map tiles). both will work when you follow the rules.

 

[TILogistic]

see:
In OSM, a valid User-Agent is VERY important.
When you make requests to its servers (for example, to the API or tiles), OSM requires you to authenticate correctly.

Example of a valid User-Agent for OSM:
MyApp/1.0 (https://myapp.com/contact)
OR:
MyApp/1.0 (user@email.com)

Add: Application name and valid email address

        j.GetRequest.SetHeader("Content-Type", "application/json")
        j.GetRequest.SetHeader("User-Agent", "MyApp/1.0 (user@email.com)")

 

[Wosl]

Thank you to both!

Setting header was the solution. I used the following coding:

j.Download(s)
j.GetRequest.SetHeader("Content-Type", "application/json")
j.GetRequest.SetHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.92 Safari/537.36")

coming from
https://www.b4x.com/android/forum/threads/set-http-request-header-with-okhttputils2.39413/#content

Important is to keep the sequence (call to Downloads before GetRequest.SetHeader) otherwise a null pointer exception will come up.

Wosl

 

[Erel]

Tip: use j.GetRequest.SetContentType for the content type header, otherwise it will be overridden.

 

[TILogistic]

Thank you to both!

Setting header was the solution. I used the following coding:

j.Download(s)
j.GetRequest.SetHeader("Content-Type", "application/json")
j.GetRequest.SetHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.92 Safari/537.36")

coming from
https://www.b4x.com/android/forum/threads/set-http-request-header-with-okhttputils2.39413/#content

Important is to keep the sequence (call to Downloads before GetRequest.SetHeader) otherwise a null pointer exception will come up.

Wosl

You can use that browser-style user agent, but it's "not recommended for OpenStreetMap (especially for services like Nominatim)."

Problem with that user agent:
Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 ...

* It's generic; it looks like a normal browser.
* It doesn't identify your application.

It goes against the OSM usage policy.

It can lead to:
* IP blocking
* Stricter rate limiting

What you should do instead:

Use a descriptive user agent that clearly identifies your application:

MyMapApp/1.0 (myemail@example.com)

Or, if you prefer, you can combine both:

MyMapApp/1.0 (myemail@example.com) Mozilla/5.0 (...)

Simple rule:

If you make automated requests:
Always include the application name, version, and contact information.

Review the OSM documentation

 

[TILogistic]

Tip: use j.GetRequest.SetContentType for the content type header, otherwise it will be overridden.

Why use what you say?

When to Use SetContentType or SetHeader("Content-Type", ...)

Hi, Am using jOkhttputils2 to call an API The main transaction method uses POST and the call was successful whiles using setContentType to set the header But when using GET request to check the status of the transaction setContentType keeps giving me an error. Meanwhile...

www.b4x.com

 

[TILogistic]

sample:

Private Sub GeoCoderNominatim (Query As String) As ResumableSub
    Dim Result As String
    Dim Parameters() As String = Array As String ("q", Query, "format", "json", "addressdetails", "1")
    Dim j As HttpJob
    j.Initialize("", Me)
    j.Download2("https://nominatim.openstreetmap.org/search", Parameters)
'    j.GetRequest.SetContentType("application/json") ' It generates an error.
    j.GetRequest.SetHeader("Content-Type", "application/json")
    j.GetRequest.SetHeader("User-Agent", "appname/1.0 (youuser@email.com)")
    j.GetRequest.Timeout = 60 * DateTime.TicksPerSecond
    Wait For (j) JobDone(j As HttpJob)
    If j.Success Then
        Result = j.GetString
    Else
        Log(j.ErrorMessage)
    End If
    j.Release
    Return Result
End Sub

 

[Erel]

Why use what you say?

When to Use SetContentType or SetHeader("Content-Type", ...)

Hi, Am using jOkhttputils2 to call an API The main transaction method uses POST and the call was successful whiles using setContentType to set the header But when using GET request to check the status of the transaction setContentType keeps giving me an error. Meanwhile...

www.b4x.com

Good point. You are correct.

For GET (Job.Download) requests, the Content-Type should be set with SetHeader.