Easy Dynamics 365/AX Blockchain Integration

This post continues to explore Blockchain integration into Microsoft Dynamics 365 for Finance and Operations (AX). I’ve seen examples where developers did integration using the MetaMask Chrome extension, however I want something that looks and feels like pure AX.

For this post I will be using Xalentis Fusion which provides seamless Blockchain integration, whereby Blockchain I refer to Ethereum. I don’t see much use for Bitcoin, and apart from hundreds of other altcoins available, I see more enterprise-level movement towards Ethereum or its variants, including JP Morgans’ Quorum or Microsoft “Project Bletchley”.

Xalentis Fusion works by detecting new transactions in an Ethereum Blockchain and allows filtering to take place across those. Once a filter detects your specific requirements, it can fire off any number of associated rules, written in simple script. Fusion also includes a growing API allowing REST-based integration with the outside world, which is what we will be using.

Fusion provides a Transact API method allowing transactions to be made via a REST call. We can do this ourselves easily as well, but since we’ll be using Fusion for more than transacting (later on in this post) I figured I’ll just stick with it.

We’ll keep it very basic, and create a simple form accepting a number of parameters that we will use to perform a transaction. Our form design is shown below.

BeforeTransact

We’ve added fields for Node, Sender, Recipient, Sender’s account Password, and the amount of Wei to send. Depending on the Ethereum network you are connecting to, adjust the Node value accordingly, or simply hardcode it and remove the field. We are using the Fusion Test Net so that is shown. I’ve created two addresses in the Test Net, also shown in the form design, and loaded the first with some Ether. Perhaps customers want to trade in Dollars, so you can add code to convert Dollars entered into Wei or whatever token is in use. We’ll stick with Wei for now.

Let’s submit this transaction.

AfterTransact

As you can see, the transaction has been submitted to the Blockchain and an Infolog displayed showing success. The X++ code is shown below, including the form class and a utility class that performs our REST calls to Fusion. I’ve added a TransactionRequest class as the POST action we are performing requires JSON being passed, and wrapped the class members with the DataContract attributes to enable easy serialization. This particular POST call accepts the full JSON as part of the POST URL, wrapped as Base64, and that is done in the utility class. The body is required, so we set the content-length to 0.

[DataContractAttribute]
class TransactRequestClass
{
    str addressFrom;
    str addressTo;
    str node;
    str password;
    str wei;

    [DataMemberAttribute]
    public str AddressFrom(str _addressFrom = addressFrom)
    {
        addressFrom = _addressFrom;
        return addressFrom;
    }

    [DataMemberAttribute]
    public str AddressTo(str _addressTo = addressTo)
    {
        addressTo = _addressTo;
        return addressTo;
    }

    [DataMemberAttribute]
    public str Node(str _node = node)
    {
        node = _node;
        return node;
    }

    [DataMemberAttribute]
    public str Password(str _password = password)
    {
        password = _password;
        return password;
    }

    [DataMemberAttribute]
    public str Wei(str _wei = wei)
    {
        wei = _wei;
        return wei;
    }
}

class FusionUtilityClass
{
    public static str Transact(str addressFrom, str addressTo, str password, str node, str wei)
    {
        System.Net.WebClient webClient;
        System.Text.UTF8Encoding encoder;
        System.Text.UnicodeEncoding decoder;
        System.IO.Stream s;
        System.IO.StreamReader sr;
        System.Net.HttpWebRequest myRequest;
       
        try
        {
            TransactRequestClass request = new TransactRequestClass();
            request.AddressFrom(addressFrom);
            request.AddressTo(addressTo);
            request.Node(node);
            request.Password(password);
            request.Wei(wei);

            encoder = new System.Text.UTF8Encoding();
            str json = FormJsonSerializer::serializeClass(request);
            System.Byte[] encodedBytes = encoder.GetBytes(json);
            str encoded64 = System.Convert::ToBase64String(encodedBytes);
 
            str url = "http://fusionapi.azurewebsites.net/api/transact?bodyJson=" + encoded64;
            myRequest = System.Net.WebRequest::Create(url);
            myRequest.Method = "POST";
            myRequest.Timeout = 30000;
            myRequest.ContentLength = 0;

            System.Net.WebHeaderCollection headers = myRequest.Headers;
            headers.Add("API_KEY", "your fusion api key");

            s = myRequest.GetResponse().GetResponseStream();
            sr = new System.IO.StreamReader(s);
            str txnHash = sr.ReadToEnd();
            s.Close();
            sr.Close();
            return txnHash;
        }
        catch (Exception::Error)
        {
        }
        return "";
    }
}

class XalentisTestFormClass
{
    
    [FormControlEventHandler(formControlStr(XalentisTestForm, FormButtonControl1), FormControlEventType::Clicked)]
    public static void FormButtonControl1_OnClicked(FormControl sender, FormControlEventArgs e)
    {
        FormStringControl nodeControl = sender.formRun().control(sender.formRun().controlId("FormStringControl1"));
        FormStringControl addressSenderControl = sender.formRun().control(sender.formRun().controlId("FormStringControl2"));
        FormStringControl addressRecipientControl = sender.formRun().control(sender.formRun().controlId("FormStringControl3"));
        FormStringControl passwordControl = sender.formRun().control(sender.formRun().controlId("FormStringControl4"));
        FormStringControl weiControl = sender.formRun().control(sender.formRun().controlId("FormStringControl5"));

        str addressFrom = addressSenderControl.Text();
        str node = nodeControl.Text();
        str addressTo = addressRecipientControl.Text();
        str password = passwordControl.Text();
        str wei = weiControl.Text();

        str txnHash = FusionUtilityClass::Transact(addressFrom, addressTo, Password, node, wei);
        //todo: store txnHash for history purposes.

        info("Transaction Posted");
    }
}

That works pretty well, but users don’t understand Blockchain addresses, and it would be painful to maintain that somewhere in notepad or Excel to copy and paste each time a transaction is made. Luckily Fusion provides an Account Mapping facility, which is a customer-specific key/value table mapping Blockchain addresses to friendly names, or account numbers the rest of us can readily understand.

So instead of entering address for Sender and Recipient, let’s modify our form as shown below. We can use drop-downs to pull up a list of known accounts, or use an API call to Fusion to return a full list of mapped accounts which we can then allow users to select. I’ll keep it simple with a text field. Here we’ve entered two known friendly account names we can read and verify. These could come from your chart of accounts as well, whatever works best in your scenario. As long as the display text maps to an address in Fusion, it can be resolved.

BeforeTransact2

I’ve modified our form class and utility class to add two additional API calls to Fusion to resolve the friendly names to Ethereum addresses as shown in the code below. We simply make a GET call to Fusion passing across the friendly name, and Fusion will perform the lookup, returning the proper Ethereum address we need to use when performing the transaction. The updated code is shown below.

class XalentisTestFormClass
{
    
    [FormControlEventHandler(formControlStr(XalentisTestForm, FormButtonControl1), FormControlEventType::Clicked)]
    public static void FormButtonControl1_OnClicked(FormControl sender, FormControlEventArgs e)
    {
        FormStringControl addressSenderControl = sender.formRun().control(sender.formRun().controlId("FormStringControl2"));
        FormStringControl addressRecipientControl = sender.formRun().control(sender.formRun().controlId("FormStringControl3"));
        FormStringControl passwordControl = sender.formRun().control(sender.formRun().controlId("FormStringControl4"));
        FormStringControl weiControl = sender.formRun().control(sender.formRun().controlId("FormStringControl5"));

        str addressFrom = addressSenderControl.Text();
        str addressTo = addressRecipientControl.Text();
        str password = passwordControl.Text();
        str wei = weiControl.Text();

        str txnHash = FusionUtilityClass::Transact(addressFrom, addressTo, Password, wei);
        //todo: store txnHash for history purposes.

        info("Transaction Posted");
    }
}

class FusionUtilityClass
{
    public static str Transact(str accountFrom, str accountTo, str password, str wei)
    {
        System.Net.WebClient webClient;
        System.Text.UTF8Encoding encoder;
        System.Text.UnicodeEncoding decoder;
        System.IO.Stream s;
        System.IO.StreamReader sr;
        System.Net.HttpWebRequest myRequest;
       
        try
        {
            str addressFrom;
            str addressTo;

            str url = "http://fusionapi.azurewebsites.net/api/address/" + strReplace(accountFrom, " ","%20");
            myRequest = System.Net.WebRequest::Create(url);
            myRequest.Method = "GET";
            myRequest.Timeout = 30000;
            System.Net.WebHeaderCollection headers = myRequest.Headers;
            headers.Add("API_KEY", your fusion api key);
            s = myRequest.GetResponse().GetResponseStream();
            sr = new System.IO.StreamReader(s);
            addressFrom = sr.ReadToEnd();
            s.Close();
            sr.Close();

            url = "http://fusionapi.azurewebsites.net/api/address/" + strReplace(accountTo, " ","%20");
            myRequest = System.Net.WebRequest::Create(url);
            myRequest.Method = "GET";
            myRequest.Timeout = 30000;
            headers = myRequest.Headers;
            headers.Add("API_KEY", "your fusion api key");
            s = myRequest.GetResponse().GetResponseStream();
            sr = new System.IO.StreamReader(s);
            addressTo = sr.ReadToEnd();
            s.Close();
            sr.Close();

            TransactRequestClass request = new TransactRequestClass();
            request.AddressFrom(strReplace(addressFrom,"\"",""));
            request.AddressTo(strReplace(addressTo,"\"",""));
            request.Node("http://xaleth4kq.eastus.cloudapp.azure.com:8545"); // hardcoded now
            request.Password(password);
            request.Wei(wei);
            encoder = new System.Text.UTF8Encoding();
            str json = FormJsonSerializer::serializeClass(request);
            System.Byte[] encodedBytes = encoder.GetBytes(json);
            str encoded64 = System.Convert::ToBase64String(encodedBytes);
            url = "http://fusionapi.azurewebsites.net/api/transact?bodyJson=" + encoded64;
            myRequest = System.Net.WebRequest::Create(url);
            myRequest.Method = "POST";
            myRequest.Timeout = 30000;
            myRequest.ContentLength = 0;
            headers = myRequest.Headers;
            headers.Add("API_KEY", "your fusion api key");
            s = myRequest.GetResponse().GetResponseStream();
            sr = new System.IO.StreamReader(s);
            str txnHash = sr.ReadToEnd();
            s.Close();
            sr.Close();
            return txnHash;
        }
        catch (Exception::Error)
        {
        }
        return "";
    }
}

We’ll submit this transaction, and as shown we’ve got success.

AfterTransact2

I hope this was helpful. One final item to note is using Wei, which is a BigInteger. I’ve used strings to remove the need for dealing with BigInteger types in X++.

 

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GPS, IoT, Blockchain Integration to ERP

I’ve read a number of articles discussing how Blockchain could have a significant impact on Trade & Logistics, especially item tracking. Granted, Blockchain is not a requirement for shipment tracking, but it does deliver a number of benefits through being a shared, secure ledger that, depending on the network, could provide an automatic openness almost immediately. That is a vast improvement over building a custom customer and partner portal to query legacy backend systems.

Of course, there remains the problem of now having to integrate Blockchain into your legacy ERP system, a whole different level of headache. So, in this post I’m going to do a simple POC to simulate how easy, or hard, it would be to build an item tracking service using Ethereum Blockchain, add to that GPS tracking with temperature and humidity monitoring, and get that to your ERP system, in this case Microsoft Dynamics 365. I want to achieve that without modifying the ERP system in any way, by using Microsoft Flow, a PowerApp and Microsoft Common Data Service. The idea is that end users, customers or partners can use the PowerApp to monitor shipments and climate conditions in real-time. Supply-chain visibility every step of the way, basically.

To start, I built a simple IoT monitoring device around the Adafruit Huzzah. I’ll be using WiFi here, making a wild assumption that WiFi is available wherever this device goes. In the real world, GPRS or Loran might be more suitable, but I don’t have that available in my toolkit just yet and besides, this is an experiment only. I’ve added a low-cost GPS, DHT11 temperature and humidity sensor, and an LCD screen to show me what is happening without requiring connecting to my laptop via the serial interface. The basic IoT device is shown below, with GPS and DHT-11 working and transmitting data.

Circuit

The C code for the IoT device is shown below. I do a POST to my Ethereum network of choice with hardcoded addresses, and embed the GPS coordinates and DHT11 state into the data portion of the Ethereum transaction. Addressing and data is entirely up to you; perhaps instead of hardcoding, this can all be read off an SD card.

#include <DHT.h>
#include "TinyGPS++.h"
#include <SoftwareSerial.h>
#include <Adafruit_SSD1306.h>
#include <ESP8266HTTPClient.h>
#include <ESP8266WiFi.h>
#include <ArduinoJson.h>
#include <Wire.h>
#include "Adafruit_GFX.h"
#include "Adafruit_SSD1306.h"

#define SSID "WiFiSSID" 
#define PASS "mypassword" 
#define OLED_RESET LED_BUILTIN
#define DHTPIN 12
#define DHTTYPE DHT11

TinyGPSPlus gps;
DHT dht(DHTPIN, DHTTYPE);
Adafruit_SSD1306 display(OLED_RESET);
SoftwareSerial mySerial(13, 15);

const char *gpsStream =
  "$GPRMC,045103.000,A,3014.1984,N,09749.2872,W,0.67,161.46,030913,,,A*7C\r\n"
  "$GPGGA,045104.000,3014.1985,N,09749.2873,W,1,09,1.2,211.6,M,-22.5,M,,0000*62\r\n"
  "$GPRMC,045200.000,A,3014.3820,N,09748.9514,W,36.88,65.02,030913,,,A*77\r\n"
  "$GPGGA,045201.000,3014.3864,N,09748.9411,W,1,10,1.2,200.8,M,-22.5,M,,0000*6C\r\n"
  "$GPRMC,045251.000,A,3014.4275,N,09749.0626,W,0.51,217.94,030913,,,A*7D\r\n"
  "$GPGGA,045252.000,3014.4273,N,09749.0628,W,1,09,1.3,206.9,M,-22.5,M,,0000*6F\r\n";

void setup() {
  Serial.begin(9600);
  dht.begin();
  display.setCursor(0,0);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.display();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.println("Connecting");
  display.println("to");
  display.println("WiFi...");
  display.display();

  WiFi.begin(SSID, PASS);
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  } 
  display.clearDisplay();
  display.display();
  display.setCursor(0,0);
  display.println("EtherGPS");
  display.println("www.xalentis.com");
  display.display();
  mySerial.begin(38400); // GPS
  delay(5000); // warm up GPS 
  display.clearDisplay();
  display.display();
  display.setCursor(0,0);
  display.println("Scanning...");
  display.display();
}

void loop() 
{
  while (*gpsStream)
    if (gps.encode(*gpsStream++))
      updateInfo();
}

void updateInfo()
{
  float h = dht.readHumidity();
  float t = dht.readTemperature();

  if (gps.location.isValid())
  {
    display.clearDisplay();
    display.display();
    display.setCursor(0,0);
    display.println("Temp:" + String(t));
    display.println("Hum:" + String(h));
    display.println("Lat:" + String(gps.location.lat()));
    display.println("Lon:" + String(gps.location.lng()));
    display.display();

    String data = "0x";
    String deviceSerial = "3132333435"; // 12345 in HEX
    data = data + deviceSerial + "2c"; // comma
    
    String temp = String(t);
    String hum = String(h);
    String lat = String(gps.location.lat());
    String lon = String(gps.location.lng());
    byte buffer[255]={0};
    
    //temp
    temp.getBytes(buffer, 255, 0);
    for (int i=0;i<=temp.length()-1;i++)
    {
      data = data + String((int)buffer[i], HEX);
    }
    data = data + deviceSerial + "2c"; // comma

    //hum
    hum.getBytes(buffer, 255, 0);
    for (int i=0;i<=hum.length()-1;i++)
    {
      data = data + String((int)buffer[i], HEX);
    }
    data = data + deviceSerial + "2c"; // comma

    //latitude
    lat.getBytes(buffer, 255, 0);
    for (int i=0;i<=lat.length()-1;i++)
    {
      data = data + String((int)buffer[i], HEX);
    }
    data = data + deviceSerial + "2c"; // comma

    //longitude
    lon.getBytes(buffer, 255, 0);
    for (int i=0;i<=lon.length()-1;i++)
    {
      data = data + String((int)buffer[i], HEX);
    }

    // build up our Ethereum transaction
    StaticJsonBuffer<1000> JSONbufferTwo;  
    JsonObject& uploadJSON = JSONbufferTwo.createObject(); 
    uploadJSON["jsonrpc"] = "2.0";
    uploadJSON["method"] = "personal_sendTransaction";      
    JsonArray&  uploadQueryParams = uploadJSON.createNestedArray("params");
    JsonObject& callTxParams = JSONbufferTwo.createObject();
    callTxParams["from"] = "0x27f6f763ae5c52721db57c4423c298a78de1f22a";
    callTxParams["to"] = "0xcaade3aa018d57d808fceb16824c47dfd206484c";
    callTxParams["value"] = "0x6FC23AC00"; //hex value 30 Gwei 
    callTxParams["gas"] = "0x30D40"; //hex value for 200000 -high gas limit for good measure          
    callTxParams["gasPrice"] = "0x6FC23AC00"; //hex value 30 Gwei gasprice 21gwei is typical
    callTxParams["data"] = data; // device,tem,hum,lat,long
    uploadQueryParams.add(callTxParams);
    uploadQueryParams.add("myetherpassword");
    uploadJSON["id"] = 1;
    String uploadString;
    uploadJSON.printTo(uploadString);
    callGeth(uploadString); // send for mining
  }
}

String callGeth(String inputJSON) 
{
  HTTPClient http;
  http.begin("http://13.72.73.21:8545/");
  http.addHeader("Content-Type", "application/json");
  int httpCode = http.POST(inputJSON);
  String JSONResult = http.getString(); // contains Txn
  http.end();
  return JSONResult;
}

At this point the transactions are flowing to the Blockchain network and that is great, but we need to be able to monitor the Blockchain for transactions we are interested in, so we can pull that off the Blockchain and into an ERP system, right?

The easiest way to do that is to use Xalentis Fusion. Sign up for a trial account at www.xalentis.com or grab it via Microsoft AppSource. Once signed-up, and logged-in, you’ll end up at the main dashboard as shown below.

xalgps1

Follow the Getting Started tutorial which takes about 10 minutes to create a pair of accounts and top them up with credit as required. The Ethereum network being used is a canned version of Microsoft’s Project Bletchley, so it’s not on the main or test Ethereum networks and can be used without spending any real Ether. You can deploy your own network and use that within the Fusion platform as well, by creating transaction filters pointing to your own deployed RPC node. Make sure your RPC node is visibly outside your firewall, obviously.

The following image shows us having created a transaction filter to monitor the default RPC node at http://xaleth4kq.eastus.cloudapp.azure.com, for any transactions made from the address 0x27f6f763ae5c52721db57c4423c298a78de1f22a. Filters can be created to match any transaction, from any address, or even containing a specific string value in the data portion. This is useful when the address(es) constantly change, while a specific identifier is passed within the data portion, perhaps a Device ID, Company ID or Serial Number of sorts – anything static.

xalgps2

Filters execute rules containing a simple compiled script, and this is where actions are performed on matching transactions. The script below has been added as a rule for our filter.

xalgps3

The rule simply extracts whatever is in the transaction data field, parses that and constructs a JSON packet. This packet will be passed to a Microsoft Flow we will be creating.

We’ll need a place to store our data. Using Flow, we could push directly into Dynamics 365, but since we don’t want to directly modify our ERP by adding a new table, I’ve chosen to use Microsoft Common Data Service as a temporary store instead. The image below shows the new Entity we’ve created with fields for Device, Temperature, Humidity, Longitude and Latitude.

GPS_CDS

Using Microsoft Flow, we’ll first use the Request action to accept an incoming POST request (from our Rule). Next, we’ll take the body of the POST request, parse it, and store the fields into our new CDS Entity. The Flow design is shown below.

GPS_Flow

Use the generated URL from the Flow to update the Rule – the final line calling Flow requires that URL.

Run the Flow, and then power up the IoT device to start submitting GPS and climate information into the Blockchain network. As transactions are mined into new blocks, Fusion will detect the transaction matching our Filter, and execute the associated Rule. The Rule in turn will parse the transaction data field, parse the content, construct it as JSON, and call our Flow with that body content. When the Flow executes, the JSON will be parsed and the data elements inserted as a new record into the CDS, as shown below.

GPS_DataCDS

We can use the data now stored in the CDS to create a PowerApp that displays that information on a Google Map. The PowerApp shown is fairly basic, but with enough time, patience and data this can be turned into something much more interactive, and it is real-time, a vast improvement over building a customer tracking portal from scratch, getting updates only when items are scanned with a barcode or RFID reader.

GPS_Map

Apart from our Rule script, we’ve used virtually no coding, and we’ve not modified our production ERP system in any way. As a bonus, we also have a mobile app that customers and partners can use!

RFID + IoT + Ethereum Blockchain

This is a very quick post, mostly code-only, showing how to read RFID tags on say an assembly line, process those using a WiFi IoT device (Adafruit Huzzah), extract the product serial number from the RFID tag and send that as part of a transaction to an Ethereum Blockchain.

I am using a MiFare RFID card reader, but you would want to use a long-range reader that supports low-cost sticker tags. POSTing the transaction to the blockchain takes a second or two, so don’t expect to scan 100 products/second flying past the reader and manage to submit those as transactions.

URL’s and codes are hard-baked, so consider how you want to post the transaction. I use static Ethereum addresses and stick the product ID in the data portion, you might want to read that from the RFID tags as well.

Once your product ID is in the blockchain, you might want to move that to your ERP system, or even a cool PowerApp or something. Unless you want to code X++ and mess around with your production systems, I suggest using Xalentis Fusion instead, to enable code-free integration between Ethereum and Microsoft Dynamics 365 for Finance and Operations. It also supports SMS, Email messaging, Service Bus messaging, Flow, PowerApps and Common Data Service.

Enjoy.

#include <SPI.h>
#include <MFRC522.h>
#include <ESP8266HTTPClient.h>
#include <ESP8266WiFi.h>
#include <ArduinoJson.h>
 
#define RST_PIN         15
#define SS_PIN          2
#define SSID            "mywifiSSID" 
#define PASS            "password" 
 
MFRC522 mfrc522(SS_PIN, RST_PIN);
 
void setup() {
  Serial1.begin(115200);
  while(!Serial1){}
  Serial.begin(9600);
  SPI.begin();
  mfrc522.PCD_Init();
  WiFi.begin(SSID, PASS);
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  }
}
 
void loop()
{
  // Using MiFare card reader here, for production use sticker tags and high-speed reader instead
  MFRC522::MIFARE_Key key; // default to FFFFFFFFFFFF
  key.keyByte[0] = 0xFF;
  key.keyByte[1] = 0xFF;
  key.keyByte[2] = 0xFF;
  key.keyByte[3] = 0xFF;
  key.keyByte[4] = 0xFF;
  key.keyByte[5] = 0xFF;
 
  // Loop until RFID tag is presented 
  if (!mfrc522.PICC_IsNewCardPresent()) return;
  if (!mfrc522.PICC_ReadCardSerial()) return;

  byte readbuffer1[18];
  byte readbuffer2[18];
  byte block;
  MFRC522::StatusCode status;
  byte len;
  byte sizeread = sizeof(readbuffer1);
  block = 0;
  
  status = mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, block, &key, &(mfrc522.uid));
  if (status != MFRC522::STATUS_OK) {
    return;
  }
  else
  {
    for (int i = 0; i < 18; i++)
    {
      readbuffer1[i] = 0x00;
      readbuffer2[i] = 0x00;
    }
    // read product ID from RFID tag
    status = mfrc522.MIFARE_Read(1, readbuffer1, &sizeread);
    if (status != MFRC522::STATUS_OK)
    {
      return;
    }
    mfrc522.PICC_HaltA();
    mfrc522.PCD_StopCrypto1();
  }
 
  // convert product ID from RFID tag to hex string
  String data = "0x";
  for (int j=0; j<18;j++)
  {
    if (readbuffer1[j]=='\0') break;
    data = data + String(readbuffer1[j], HEX);
  }

  // build up our Ethereum transaction
  StaticJsonBuffer<1000> JSONbufferTwo;  
  JsonObject& uploadJSON = JSONbufferTwo.createObject(); 
  uploadJSON["jsonrpc"] = "2.0";
  uploadJSON["method"] = "personal_sendTransaction";      
  JsonArray&  uploadQueryParams = uploadJSON.createNestedArray("params");
  JsonObject& callTxParams = JSONbufferTwo.createObject();
  callTxParams["from"] = "0x27f6f763ae5c52721db57c4423c298a78de1f22a";
  callTxParams["to"] = "0xcaade3aa018d57d808fceb16824c47dfd206484c";
  callTxParams["value"] = "0x6FC23AC00"; //hex value 30 Gwei 
  callTxParams["gas"] = "0x30D40"; //hex value for 200000 -high gas limit for good measure          
  callTxParams["gasPrice"] = "0x6FC23AC00"; //hex value 30 Gwei gasprice 21gwei is typical
  callTxParams["data"] = data;
  uploadQueryParams.add(callTxParams);
  uploadQueryParams.add("bigsecretaccountpassword");
  uploadJSON["id"] = 1;
  String uploadString;
  uploadJSON.printTo(uploadString);
  callGeth(uploadString); // send for mining
}

String callGeth(String inputJSON) // thanks to https://github.com/gusgorman402
{
  HTTPClient http;
  http.begin("http://your RPC address here:8545/");
  http.addHeader("Content-Type", "application/json");
  int httpCode = http.POST(inputJSON);
  String JSONResult = http.getString(); // contains Txn
  http.end();
  return JSONResult;
}