Added description of Sqlbi.PbiPushDataset library

Author: marcosqlbi

README.md

@@ -9,3 +9,73 @@ There are three projects included in the repository:
 *	**PbiPushTools**: it is a command-line tool that internally uses the Sqlbi.PbiPushDataset library. This tool does not require programming skills to create, maintain, and test a push dataset model.
 *	**Sqlbi.PbiPushTools**: it is a PowerShell cmdlet to create, maintain, and test a push dataset model. The cmdlet internally uses the Sqlbi.PbiPushDataset library and is an alternative to the command-line tool. This cmdlet does not require programming skills to create, maintain, and test a push dataset model. The PowerShell cmdlet is compatible with PowerShell scripts managed by Azure Functions. The cmdlet is available in the [PowerShell gallery](https://www.powershellgallery.com/packages/Sqlbi.PbiPushTools/).
 
+## Sqlbi.PbiPushDataset
+The **[PbiConnection](https://github.com/sql-bi/Pbi-PushDataset/blob/main/Sqlbi.PbiPushDataset/PbiConnection.cs)** class is a wrapper of the push datasets features included in the Power BI REST API. 
+The push dataset is created starting from a Tabular Object Model (TOM) structure, removing the unsupported features (like user hierarchies and inactive relationships).
+The push dataset can be initialized reading data from another Power BI dataset.
+The class handles service principal authentication and user authentication for the refresh operation.
+The class also includes a simulator that creates and write rows according to a configuration table.
+The public methods available are:
+* **CreatePushDataset**: Creates a push dataset in the specified workspace using the TOM model retrieved from a model.bim file.
+* **AlterPushDataset**: Updates the structure of a push dataset in the specified workspace using the TOM model retrieved from a model.bim file.
+* **ClearPushDataset**: Remove all the rows from one or all the tables of a push dataset
+* **RefreshWithDax**: Writes in tables of a push dataset the result obtained by running one or more DAX queries on another dataset published on the same Power BI tenant (also on a different workspace).
+* **PushSimulation**: Runs a simulation writing rows in one or more tables of a push dataset at intervals specified by the simulator configuration.
+
+### Simulator configuration
+This is a sample of the simulator configuration file.
+* **batchInterval** is the number of seconds between each batch of rows generated.
+* **batchRows** is the number of rows generated in each batch.
+* **type** is the algorithm used to generate values for a column, can be **Fixed**, **List**, or **Range**.
+* **fixedValue** is the value assigned to a column for the **Fixed** algorithm
+* **allowedValues** is a list of values allowed for the **List** algorithm
+* **range** describe the range of valuesfor the **Range** algorithm:
+    - **min** is the minimum value
+    - **max** is the maximum value
+    - **granularity** is the range granularity: use 0 for integers, 1 = 0.1, 2 = 0.01, -2 = multiple of 100
+```json
+{
+    "batchInterval": 2,
+    "tables": [
+        {
+            "name": "Sales",
+            "batchRows": 98,
+            "columns": [
+                {
+                    "name": "Quantity",
+                    "type": "List",
+                    "allowedValues": [1,2,3,4,5,6,7,8,9,10]
+                },
+                {
+                    "name": "Net Price",
+                    "type": "Range",
+                    "range": {
+                        "min": 10.0,
+                        "max": 200.0,
+                        "granularity": 0
+                    }
+                },
+                {
+                    "name": "Unit Price",
+                    "type": "Range",
+                    "range": {
+                        "min": 200.0,
+                        "max": 2000.0,
+                        "granularity": 0
+                    }
+                },
+                {
+                    "name": "Order Date",
+                    "type": "Fixed",
+                    "fixedValue": "2020-03-05"
+                },
+                {
+                    "name": "StoreKey",
+                    "type": "List",
+                    "allowedValues": [550,999999,400,210,585,605,230,620,190,465,180,420,290,670,300,80,510,590,610,430,440,450,35,200,540,170,90,650,380,50,240,570,100,220,270,370,560,500,490,360,330,630,140,470,10,255,660,340,310,40,130,530,390,160,410,480,320,260,74,60,150,120,72,280,20,250,350,460,580,520,110,30,70,600]
+                }
+            ]
+        }
+    ]
+}
+```