## Develop your own Big Data & AI applications with BigDL PPML

First you need to create a `PPMLContext`, which wraps `SparkSession` and provides methods to read encrypted data file into plain-text RDD/DataFrame and write DataFrame to encrypted data file. Then you can read & write data through `PPMLContext`.

If you are familiar with Spark, you may find that the usage of `PPMLConext` is very similar to Spark.

### 1. Create PPMLContext

- create a PPMLContext with `appName`

   This is the simplest way to create a `PPMLContext`. When you don't need to read/write encrypted files, you can use this way to create a `PPMLContext`.

   <details open>
    <summary>scala</summary>

   ```scala
   import com.intel.analytics.bigdl.ppml.PPMLContext

   val sc = PPMLContext.initPPMLContext("MyApp")
   ```

   </details>

  <details>
    <summary>python</summary>

   ```python
   from bigdl.ppml.ppml_context import *

   sc = PPMLContext("MyApp")
   ```

   </details>

   If you want to read/write encrypted files, then you need to provide more information.

- create a PPMLContext with `appName` & `ppmlArgs`

   `ppmlArgs` is ppml arguments in a Map, `ppmlArgs` varies according to the kind of Key Management Service (KMS) you are using. Key Management Service (KMS) is used to generate `primaryKey` and `dataKey` to encrypt/decrypt data. We provide 3 types of KMS ——SimpleKeyManagementService, EHSMKeyManagementService, AzureKeyManagementService.

   Refer to [KMS Utils](https://github.com/intel-analytics/BigDL/blob/main/ppml/services/kms-utils/docker/README.md) to use KMS to generate `primaryKey` and `dataKey`, then you are ready to create **PPMLContext** with `ppmlArgs`.

  - For `SimpleKeyManagementService`:

      <details open>
       <summary>scala</summary>

      ```scala
      import com.intel.analytics.bigdl.ppml.PPMLContext

      val ppmlArgs: Map[String, String] = Map(
             "spark.bigdl.kms.type" -> "SimpleKeyManagementService",
             "spark.bigdl.kms.simple.id" -> "your_app_id",
             "spark.bigdl.kms.simple.key" -> "your_app_key",
             "spark.bigdl.kms.key.primary" -> "/your/primary/key/path/primaryKey",
             "spark.bigdl.kms.key.data" -> "/your/data/key/path/dataKey"
         )

      val sc = PPMLContext.initPPMLContext("MyApp", ppmlArgs)
      ```

      </details>


      <details>
       <summary>python</summary>

      ```python
      from bigdl.ppml.ppml_context import *

      ppml_args = {"kms_type": "SimpleKeyManagementService",
                   "simple_app_id": "your_app_id",
                   "simple_app_key": "your_app_key",
                   "primary_key_path": "/your/primary/key/path/primaryKey",
                   "data_key_path": "/your/data/key/path/dataKey"
                  }

      sc = PPMLContext("MyApp", ppml_args)
      ```

      </details>

   - For `EHSMKeyManagementService`:

      <details open>
       <summary>scala</summary>

      ```scala
      import com.intel.analytics.bigdl.ppml.PPMLContext

      val ppmlArgs: Map[String, String] = Map(
             "spark.bigdl.kms.type" -> "EHSMKeyManagementService",
             "spark.bigdl.kms.ehs.ip" -> "your_server_ip",
             "spark.bigdl.kms.ehs.port" -> "your_server_port",
             "spark.bigdl.kms.ehs.id" -> "your_app_id",
             "spark.bigdl.kms.ehs.key" -> "your_app_key",
             "spark.bigdl.kms.key.primary" -> "/your/primary/key/path/primaryKey",
             "spark.bigdl.kms.key.data" -> "/your/data/key/path/dataKey"
      )

      val sc = PPMLContext.initPPMLContext("MyApp", ppmlArgs)
      ```

     </details>

     <details>
       <summary>python</summary>

      ```python
      from bigdl.ppml.ppml_context import *

      ppml_args = {"kms_type": "EHSMKeyManagementService",
                   "kms_server_ip": "your_server_ip",
                   "kms_server_port": "your_server_port"
                   "ehsm_app_id": "your_app_id",
                   "ehsm_app_key": "your_app_key",
                   "primary_key_path": "/your/primary/key/path/primaryKey",
                   "data_key_path": "/your/data/key/path/dataKey"
                  }

      sc = PPMLContext("MyApp", ppml_args)
      ```

      </details>

   - For `AzureKeyManagementService`


     the parameter `clientId` is not necessary, you don't have to provide this parameter.

      <details open>
       <summary>scala</summary>

      ```scala
      import com.intel.analytics.bigdl.ppml.PPMLContext

      val ppmlArgs: Map[String, String] = Map(
             "spark.bigdl.kms.type" -> "AzureKeyManagementService",
             "spark.bigdl.kms.azure.vault" -> "key_vault_name",
             "spark.bigdl.kms.azure.clientId" -> "client_id",
             "spark.bigdl.kms.key.primary" -> "/your/primary/key/path/primaryKey",
             "spark.bigdl.kms.key.data" -> "/your/data/key/path/dataKey"
         )

      val sc = PPMLContext.initPPMLContext("MyApp", ppmlArgs)
      ```

     </details>

     <details>
       <summary>python</summary>

       ```python
       from bigdl.ppml.ppml_context import *

       ppml_args = {"kms_type": "AzureKeyManagementService",
                    "azure_vault": "your_azure_vault",
                    "azure_client_id": "your_azure_client_id",
                    "primary_key_path": "/your/primary/key/path/primaryKey",
                    "data_key_path": "/your/data/key/path/dataKey"
                   }

       sc = PPMLContext("MyApp", ppml_args)
       ```

     </details>

- create a PPMLContext with `sparkConf` & `appName` & `ppmlArgs`

   If you need to set Spark configurations, you can provide a `SparkConf` with Spark configurations to create a `PPMLContext`.

   <details open>
    <summary>scala</summary>

   ```scala
   import com.intel.analytics.bigdl.ppml.PPMLContext
   import org.apache.spark.SparkConf

   val ppmlArgs: Map[String, String] = Map(
       "spark.bigdl.kms.type" -> "SimpleKeyManagementService",
       "spark.bigdl.kms.simple.id" -> "your_app_id",
       "spark.bigdl.kms.simple.key" -> "your_app_key",
       "spark.bigdl.kms.key.primary" -> "/your/primary/key/path/primaryKey",
       "spark.bigdl.kms.key.data" -> "/your/data/key/path/dataKey"
   )

   val conf: SparkConf = new SparkConf().setMaster("local[4]")

   val sc = PPMLContext.initPPMLContext(conf, "MyApp", ppmlArgs)
   ```

  </details>

  <details>
    <summary>python</summary>

   ```python
   from bigdl.ppml.ppml_context import *
   from pyspark import SparkConf

   ppml_args = {"kms_type": "SimpleKeyManagementService",
                "simple_app_id": "your_app_id",
                "simple_app_key": "your_app_key",
                "primary_key_path": "/your/primary/key/path/primaryKey",
                "data_key_path": "/your/data/key/path/dataKey"
               }

   conf = SparkConf()
   conf.setMaster("local[4]")

   sc = PPMLContext("MyApp", ppml_args, conf)
   ```

  </details>

### 2. Read and Write Files

To read/write data, you should set the `CryptoMode`:

- `plain_text`: no encryption
- `AES/CBC/PKCS5Padding`: for CSV, JSON and text file
- `AES_GCM_V1`: for PARQUET only
- `AES_GCM_CTR_V1`: for PARQUET only

To write data, you should set the `write` mode:

- `overwrite`: Overwrite existing data with the content of dataframe.
- `append`: Append content of the dataframe to existing data or table.
- `ignore`: Ignore current write operation if data / table already exists without any error.
- `error`: Throw an exception if data or table already exists.
- `errorifexists`: Throw an exception if data or table already exists.

<details open>
  <summary>scala</summary>

```scala
import com.intel.analytics.bigdl.ppml.crypto.{AES_CBC_PKCS5PADDING, PLAIN_TEXT}

// read data
val df = sc.read(cryptoMode = PLAIN_TEXT)
         ...

// write data
sc.write(dataFrame = df, cryptoMode = AES_CBC_PKCS5PADDING)
.mode("overwrite")
...
```

</details>

<details>
  <summary>python</summary>

```python
from bigdl.ppml.ppml_context import *

# read data
df = sc.read(crypto_mode = CryptoMode.PLAIN_TEXT)
  ...

# write data
sc.write(dataframe = df, crypto_mode = CryptoMode.AES_CBC_PKCS5PADDING)
.mode("overwrite")
...
```

</details>

<details><summary>expand to see the examples of reading/writing CSV, PARQUET, JSON and text file</summary>

The following examples use `sc` to represent a initialized `PPMLContext`

**read/write CSV file**

<details open>
  <summary>scala</summary>

```scala
import com.intel.analytics.bigdl.ppml.PPMLContext
import com.intel.analytics.bigdl.ppml.crypto.{AES_CBC_PKCS5PADDING, PLAIN_TEXT}

// read a plain csv file and return a DataFrame
val plainCsvPath = "/plain/csv/path"
val df1 = sc.read(cryptoMode = PLAIN_TEXT).option("header", "true").csv(plainCsvPath)

// write a DataFrame as a plain csv file
val plainOutputPath = "/plain/output/path"
sc.write(df1, PLAIN_TEXT)
.mode("overwrite")
.option("header", "true")
.csv(plainOutputPath)

// read a encrypted csv file and return a DataFrame
val encryptedCsvPath = "/encrypted/csv/path"
val df2 = sc.read(cryptoMode = AES_CBC_PKCS5PADDING).option("header", "true").csv(encryptedCsvPath)

// write a DataFrame as a encrypted csv file
val encryptedOutputPath = "/encrypted/output/path"
sc.write(df2, AES_CBC_PKCS5PADDING)
.mode("overwrite")
.option("header", "true")
.csv(encryptedOutputPath)
```

</details>

<details>
  <summary>python</summary>

```python
# import
from bigdl.ppml.ppml_context import *

# read a plain csv file and return a DataFrame
plain_csv_path = "/plain/csv/path"
df1 = sc.read(CryptoMode.PLAIN_TEXT).option("header", "true").csv(plain_csv_path)

# write a DataFrame as a plain csv file
plain_output_path = "/plain/output/path"
sc.write(df1, CryptoMode.PLAIN_TEXT)
.mode('overwrite')
.option("header", True)
.csv(plain_output_path)

# read a encrypted csv file and return a DataFrame
encrypted_csv_path = "/encrypted/csv/path"
df2 = sc.read(CryptoMode.AES_CBC_PKCS5PADDING).option("header", "true").csv(encrypted_csv_path)

# write a DataFrame as a encrypted csv file
encrypted_output_path = "/encrypted/output/path"
sc.write(df2, CryptoMode.AES_CBC_PKCS5PADDING)
.mode('overwrite')
.option("header", True)
.csv(encrypted_output_path)
```

</details>

**read/write PARQUET file**

<details open>
  <summary>scala</summary>

```scala
import com.intel.analytics.bigdl.ppml.PPMLContext
import com.intel.analytics.bigdl.ppml.crypto.{AES_GCM_CTR_V1, PLAIN_TEXT}

// read a plain parquet file and return a DataFrame
val plainParquetPath = "/plain/parquet/path"
val df1 = sc.read(PLAIN_TEXT).parquet(plainParquetPath)

// write a DataFrame as a plain parquet file
plainOutputPath = "/plain/output/path"
sc.write(df1, PLAIN_TEXT)
.mode("overwrite")
.parquet(plainOutputPath)

// read a encrypted parquet file and return a DataFrame
val encryptedParquetPath = "/encrypted/parquet/path"
val df2 = sc.read(AES_GCM_CTR_V1).parquet(encryptedParquetPath)

// write a DataFrame as a encrypted parquet file
val encryptedOutputPath = "/encrypted/output/path"
sc.write(df2, AES_GCM_CTR_V1)
.mode("overwrite")
.parquet(encryptedOutputPath)
```

</details>


<details>
  <summary>python</summary>

```python
# import
from bigdl.ppml.ppml_context import *

# read a plain parquet file and return a DataFrame
plain_parquet_path = "/plain/parquet/path"
df1 = sc.read(CryptoMode.PLAIN_TEXT).parquet(plain_parquet_path)

# write a DataFrame as a plain parquet file
plain_output_path = "/plain/output/path"
sc.write(df1, CryptoMode.PLAIN_TEXT)
.mode('overwrite')
.parquet(plain_output_path)

# read a encrypted parquet file and return a DataFrame
encrypted_parquet_path = "/encrypted/parquet/path"
df2 = sc.read(CryptoMode.AES_GCM_CTR_V1).parquet(encrypted_parquet_path)

# write a DataFrame as a encrypted parquet file
encrypted_output_path = "/encrypted/output/path"
sc.write(df2, CryptoMode.AES_GCM_CTR_V1)
.mode('overwrite')
.parquet(encrypted_output_path)
```

</details>

**read/write JSON file**

<details open>
  <summary>scala</summary>

```scala
import com.intel.analytics.bigdl.ppml.PPMLContext
import com.intel.analytics.bigdl.ppml.crypto.{AES_CBC_PKCS5PADDING, PLAIN_TEXT}

// read a plain json file and return a DataFrame
val plainJsonPath = "/plain/json/path"
val df1 = sc.read(PLAIN_TEXT).json(plainJsonPath)

// write a DataFrame as a plain json file
val plainOutputPath = "/plain/output/path"
sc.write(df1, PLAIN_TEXT)
.mode("overwrite")
.json(plainOutputPath)

// read a encrypted json file and return a DataFrame
val encryptedJsonPath = "/encrypted/parquet/path"
val df2 = sc.read(AES_CBC_PKCS5PADDING).json(encryptedJsonPath)

// write a DataFrame as a encrypted parquet file
val encryptedOutputPath = "/encrypted/output/path"
sc.write(df2, AES_CBC_PKCS5PADDING)
.mode("overwrite")
.json(encryptedOutputPath)
```

</details>

<details>
  <summary>python</summary>

```python
# import
from bigdl.ppml.ppml_context import *

# read a plain json file and return a DataFrame
plain_json_path = "/plain/json/path"
df1 = sc.read(CryptoMode.PLAIN_TEXT).json(plain_json_path)

# write a DataFrame as a plain json file
plain_output_path = "/plain/output/path"
sc.write(df1, CryptoMode.PLAIN_TEXT)
.mode('overwrite')
.json(plain_output_path)

# read a encrypted json file and return a DataFrame
encrypted_json_path = "/encrypted/parquet/path"
df2 = sc.read(CryptoMode.AES_CBC_PKCS5PADDING).json(encrypted_json_path)

# write a DataFrame as a encrypted parquet file
encrypted_output_path = "/encrypted/output/path"
sc.write(df2, CryptoMode.AES_CBC_PKCS5PADDING)
.mode('overwrite')
.json(encrypted_output_path)
```

</details>

**read textfile**

<details open>
  <summary>scala</summary>

```scala
import com.intel.analytics.bigdl.ppml.PPMLContext
import com.intel.analytics.bigdl.ppml.crypto.{AES_CBC_PKCS5PADDING, PLAIN_TEXT}

// read from a plain csv file and return a RDD
val plainCsvPath = "/plain/csv/path"
val rdd1 = sc.textfile(plainCsvPath) // the default cryptoMode is PLAIN_TEXT

// read from a encrypted csv file and return a RDD
val encryptedCsvPath = "/encrypted/csv/path"
val rdd2 = sc.textfile(path=encryptedCsvPath, cryptoMode=AES_CBC_PKCS5PADDING)
```

</details>

<details>
  <summary>python</summary>

```python
# import
from bigdl.ppml.ppml_context import *

# read from a plain csv file and return a RDD
plain_csv_path = "/plain/csv/path"
rdd1 = sc.textfile(plain_csv_path) # the default crypto_mode is "plain_text"

# read from a encrypted csv file and return a RDD
encrypted_csv_path = "/encrypted/csv/path"
rdd2 = sc.textfile(path=encrypted_csv_path, crypto_mode=CryptoMode.AES_CBC_PKCS5PADDING)
```

</details>

</details>

More usage with `PPMLContext` Python API, please refer to [PPMLContext Python API](https://github.com/intel-analytics/BigDL/blob/main/python/ppml/src/bigdl/ppml/README.md).