B4J Question UniPI and Rexygen API

besoft · Aug 7, 2018

How to use it in B4J ?

B4X:

# Values to be written
value_double=17.89

# URLs of the data points
url_double="http://192.168.1.100:8008/api/tasks/rest_api_task/CNR_IN:ycn"

# Credentials
user="admin"
password="mypasswd"

echo -e "\nWriting data type double ... "
curl -d "{\"v\":$value_double}" -u "$user:$password" -H "Content-Type: application/json" -X POST $url_double

I know how to do this with jShell, I'm interested in how to correctly use HttpJob to use all the parameters.

THX

Erel · Aug 7, 2018

curl -d creates a POST request.

B4X:

j.User = ... 'or UserName, I don't remember
j.Password = ...
j.PostString(..., $"{"v":${value_double})"$)
j.GetRequest.SetContentType("application/json")
Wait For (j) JobDone(j As HttpJob)
...

[B4X] OkHttpUtils2 with Wait For

OliverA · Aug 8, 2018

Erel said:
j.PostString(..., $"{"v":${value_double}"$)

I think there is a missing }

B4X:

j.PostString(..., $"{"v":${value_double}}"$)

Erel · Aug 9, 2018

Fixed. This is what you get when you try to write json by hand...

B4X:

Dim jg As JSONGenerator
jg.Initialize(CreateMap("v": value_double))
j.PostString(..., jg.ToString)

besoft · Aug 16, 2018

I still could not do this. Now I have time to test it.
My code:

B4X:

Sub Process_Globals
    Private fx As JFX
    Private MainForm As Form
    Private vrednost As Double = 20.00
    Private url_ As String = "http://192.168.1.100:8008/api/tasks/rest_api_task/CNR_IN:ycn"
    Private user As String = "admin"
    Private pass As String = "mypasswd"
    
End Sub

Sub AppStart (Form1 As Form, Args() As String)
    MainForm = Form1
    'MainForm.RootPane.LoadLayout("Layout1") 'Load the layout file.
    MainForm.Show
    Dim job1 As HttpJob
    job1.Initialize("",Me)
    job1.Username = user
    'job1.Password = ""
    job1.GetRequest.SetContentType("application/json")
    Dim jg As JSONGenerator
    jg.Initialize(CreateMap("v": vrednost))
    job1.PostString(url_,jg)
    
    Wait For (job1) JobDone(job1 As HttpJob)
    If job1.Success Then
        Log(job1.GetString)
    End If
    job1.Release
    
End Sub

I get this error:

main$ResumableSub_AppStart.resume (java line: 97)
java.lang.RuntimeException: Request does not support this method.
at anywheresoftware.b4h.okhttp.OkHttpClientWrapper$OkHttpRequest.SetContentType(OkHttpClientWrapper.java:493)
at b4j.example.main$ResumableSub_AppStart.resume(main.java:97)
at b4j.example.main._appstart(main.java:61)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:90)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:77)
at b4j.example.main.start(main.java:38)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$161(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$174(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$172(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$173(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
at java.lang.Thread.run(Thread.java:748)

I ask for help, where did I make a mistake?
Thank you

OliverA · Aug 16, 2018

Which libraries have you checked/included in your project? If you want to use SetContentType you need to include OkHttp. With OkHttp checked, when you type job1.GetRequest. you get all the methods/properties available for the GetRequest object. Without it, you had to completely type the method name (SetContentType), unless you just happen to copy/past the code.

besoft · Aug 16, 2018

These are selected libraries.

OliverA · Aug 16, 2018

Uncheck jHTTP, jHttpUtils2 and check jOkHttpUtils2

besoft · Aug 16, 2018

Thanks for the answer, I've fixed the libraries.
The error is still the same

OliverA · Aug 16, 2018

GetRequest must come after PostString. See @Erel's post #2

besoft · Aug 16, 2018

There are no errors,
but the code does not work as it should. I need to study the API.

THX

OliverA · Aug 16, 2018

You may need to do this

B4X:

    Wait For (job1) JobDone(job1 As HttpJob)
    If job1.Success Then
        Log(job1.GetString)
    Else
        Log(job1.ErrorMessage)
    End If
    job2.Release

job1.Success will be true for 2xx HTTP return codes and false for no-2xx codes. Some API's always return 2xx codes (unless something goes totally wrong with the API application itself) and return a error message embedded in JSON (retrievable via GetString) and some API's return a non-2xx code to indicate an error (and may still provide a JSON structure for more detail. At this point, ErrorMessage should contain the JSON structure).

besoft · Aug 17, 2018

I have a Python code that works.

B4X:

import requests
import json

targetIPAddress = '192.168.8.100:8008'
taskName = 'rest_api_task'

def RexInitSession(loginREX, passwordREX):
    s = requests.Session()
    s.auth = (loginREX, passwordREX)
    s.headers.update({"Content-Type":"application/json","Accept":"application/json"})
    
    return s
        
def RexPost(session,connectionString, value):
    # Build request
    url = 'http://' + targetIPAddress + '/api/tasks/' + taskName + '/' +connectionString
    data = json.dumps({"v":value})
    # Send request
    r = session.post(url,data)
    # Process response
    if r.status_code == 200:
        ret = True
        print(connectionString + " = " + str(value) + " successfully written.")
    else:
        ret = False
        print(connectionString +" failed to write.")
    return ret

def RexGet(session, connectionString):
    # Build request
    url = 'http://' + targetIPAddress + '/api/tasks/' + taskName + '/' +connectionString
    # Send request
    r = session.get(url)
    data = r.json()['v']
    # Process response
    if r.status_code == 200:
        ret = data
        print(connectionString + " = " + str(data))
    else:
        ret = False
        print(connectionString +" failed to read.")
    return ret

# Initialize REST API session (fill in REXYGEN credentials)
s = RexInitSession('admin','')

# Read data from REXYGEN using HTTP GET request
bool = RexGet(s,'CNB_IN:Y')
long = RexGet(s,'CNI_IN:iy')
double = RexGet(s,'CNR_IN:y')
string = RexGet(s,'CNS_IN:sy')

# Write data to REXYGEN using HTTP POST request
RexPost(s,'CNB_IN:YCN', 1)
RexPost(s,'CNI_IN:icn', 1234)
RexPost(s,'CNR_IN:ycn', 18.89)
RexPost(s,'CNS_IN:scv', 'Hello from Python')

How to write it in B4J? I ask for help, I do not know how to do it.
Thank you

OliverA · Aug 17, 2018

You are setting an extra header ("Accept") that you are not setting in B4J. I also finally noticed an error in your code posted in post #5. You have

B4X:

job1.PostString(url_,jg)

but it should be

B4X:

job1.PostString(url_,jg.ToString)

This was actually done by @Erel's example post.

Adding these two changes and fixing the location of SetContentType, your code should look something like this

B4X:

Sub Process_Globals
    Private fx As JFX
    Private MainForm As Form
    Private vrednost As Double = 20.00
    Private url_ As String = "http://192.168.1.100:8008/api/tasks/rest_api_task/CNR_IN:ycn"
    Private user As String = "admin"
    'Private pass As String = "mypasswd"
    'Python sample has password as ""
    Private pass As String = ""    
End Sub

Sub AppStart (Form1 As Form, Args() As String)
    MainForm = Form1
    'MainForm.RootPane.LoadLayout("Layout1") 'Load the layout file.
    MainForm.Show

    's = requests.Session()
    Dim job1 As HttpJob  
    job1.Initialize("",Me)

    's.auth = (loginREX, passwordREX)
    job1.Username = user 
    job1.Password = pass
   
    'job1.GetRequest.SetContentType("application/json") 'Wrong location

    'data = json.dumps({"v":value})
    Dim jg As JSONGenerator
    jg.Initialize(CreateMap("v": vrednost))

    'r = session.post(url,data)
    job1.PostString(url_,jg.ToString)

    's.headers.update({"Content-Type":"application/json","Accept":"application/json"})
    job1.GetRequest.SetContentType("application/json")
    job1.GetRequest.SetHeader("Accept", "application/json")

    Wait For (job1) JobDone(job1 As HttpJob)

    'if r.status_code == 200:
    If job1.Success Then
        Log(job1.GetString)
    Else
        Log(job1.ErrorMessage)
    End If
    job1.Release
    
End Sub

The one "big" difference is that in python you set up a "session" only once. This seems to be equivalent to HttpJob in B4J, but in B4J, you have to create a new HttpJob per request.

besoft · Aug 18, 2018

Thanks for the reply,
I missed this part:

B4X:

    job1.GetRequest.SetContentType("application/json")
job1.GetRequest.SetHeader("Accept", "application/json")

I will try and report.

THX

besoft · Aug 18, 2018

<!DOCTYPE html><html class="mdc-typography"><head><meta charset="utf-8" /><link rel="icon shortcut" sizes="any" href="/resources/images/favicon.ico"><link rel="stylesheet" href="/resources/css/rex-material-components-web.css"><link rel="stylesheet" href="/resources/css/rex.css"><link rel="stylesheet" href="/resources/css/rex-main.css"><script src="/resources/js/material-components-web.js"></script></head><body><header id="header"><a id="logo" href="/"></a><div id="header-title"></div></header><div id="main-block"><main id="content" class=""><div class="mdc-card mdc-card__standalone-form--narrow flex-form"><section class="mdc-card__primary"><h1 class="mdc-card__title mdc-card__title--extra-large"><span class="material-icons material-icons--standard">account_box</span></h1></section><section class="mdc-card__supporting-text"><form method="post" action="login" accept-charset="UTF-8"><input name="url" type="hidden" value="/"><div class="mdc-text-field mdc-text-field--dense" data-mdc-auto-i...

This is the text that I get back to LOG. The value of the parameter was not updated on the controller to the value: 20.

I suppose there is something wrong with this part of the code:

B4X:

job1.GetRequest.SetContentType("application/json")
job1.GetRequest.SetHeader("Accept", "application/json")

Is it possible to check if the header is correctly set?

PS
Python code is not mine, it's part of API Examples.

OliverA · Aug 18, 2018

<form method="post" action="login" accept-charset="UTF-8">

Looks like you're getting back a log in form

besoft · Aug 22, 2018

Maybe someone else has an idea, what could be wrong?

Thank you

besoft · Aug 26, 2018

I'm still exploring the API. If I use a debug, the line job1.Initialize gets false at job1 success. I suppose this is wrong ?

DonManfred · Aug 26, 2018

The Job isn´t started at this point. Sure the value of success is false.

Go further with the flow and wait to get the result event get raised. The event happens after the Job finishes. Check the values here as they now contains the result from the called job.

B4J Question UniPI and Rexygen API

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