# A1 Policy Enforcement Simulator (A1 PE Simulator)

This simulator supports standard A1-P OSC\_2.1.0 interface. In addition, internal APIs are provided to manage the RAN elements (Cells, UEs) and to customize and send VES Events. A1 PE Simulator can send legacy VES events as well as FileReady events.

## How to use the A1 PE Simulator?

### RAN

A1 PE Simulator needs two main files to define the topology (cells) and user equipments that should be managed (those cells/UEs are then used in A1 Policy Enforcement loop).

- doc/resource/cells.json

```json
{
  "cellList": [
    {
      "Cell": {
        "networkId": "RAN001",
        "nodeId": "Cell1",
        "physicalCellId": 0,
        "pnfName": "ncserver1",
        "sectorNumber": 0,
        "latitude": "50.11",
        "longitude": "19.98"
      },
      "neighbor": [
        {
          "nodeId": "Cell3",
          "blacklisted": "false"
        },
        {
          "nodeId": "Cell4",
          "blacklisted": "false"
        },
        {
          "nodeId": "Cell2",
          "blacklisted": "false"
        }
      ]
    }
}
```

- doc/resource/ue.json

```json
[
    {
        "id": "emergency_samsung_s10_01",
        "latitude": "50.09",
        "longitude": "19.94",
        "cellId": "Cell1"
    },
    {
        "id": "emergency_police_01",
        "latitude": "50.035",
        "longitude": "19.97",
        "cellId": "Cell3"
    }
]
```

The locations of these files are defined in *src/main/resources/application.properties*.

Important: The vnf.config, cells.json and ue.json files should be under */var/a1pesim/*  (default folder location, can be changed).
Copy the content of **doc/resources/** to this location on the host that will be running the simulator.

To change the default locations, see:

- **Run A1 PE Simulator with a new configuration**

To refresh the content of those files on runtime, see:

- **Refresh the configuration files on runtime**

### VES

A1 PE Simulator provides REST endpoints that can be used to trigger sending of VES events to DMaaP topic via VES-COLLECTOR (DCAE MS).

The file **vnf.config** provides the connectivity configuration to VES Collector and FTP server as well as some commonEventHeader default values (like sourceId and sourceName):

```
vesHost=vesconsumer
vesPort=30417
vesUser=sample1
vesPassword=sample1
vnfId=de305d54-75b4-431b-adb2-eb6b9e546014
vnfName=ibcx0001vm002ssc001
ftpHost=localhost
ftpPort=22222
repPeriod=90
```

- vesHost defines the hostname of the VES consumer
- vesPort defines the port on which consumer expects events
- ftpHost defines the hostname to FTP server
- ftpPort defines the port of FTP server
- repPeriod defines Reporting period for fileReady events in seconds
- vesUser and vesPassword are used to create the BasicAuth header in the request
- vnfId, vnfName map to the VES event -> commonEventHeader content:

```json
{
    "event":{
        "commonEventHeader": {
            "sourceId": "de305d54-75b4-431b-adb2-eb6b9e546014",
            "sourceName": "ibcx0001vm002ssc001",
            ...
        },
        ...
}
```

Cells can send two types of VES events: **normal** and **failure**.
In both cases the VES event values are mostly the same;
the only difference is that *measurementFields.additionalMeasurements.latency/throughput* values are generated by using different algorithms.

- for normal VES Events

```json
{
  ...
  "measurementFields" : {
              "additionalMeasurements" : [
                  {
                      "name": "latency",
                      "hashMap": {
                          "value": "[[10-150]]"
                      }
                  },
                  {
                      "name": "throughput",
                      "hashMap": {
                          "value": "[[10-100]]"
                      }
                  }
              ],
              ...
  }
}
```

**10-150** means that the generated values will oscillate between 10 and 150

- for failure VES Events

```json
{
...
"measurementFields" : {
            "additionalMeasurements" : [
                {
                    "name": "latency",
                    "hashMap": {
                        "value": "[[200->500]]"
                    }
                },
                {
                    "name": "throughput",
                    "hashMap": {
                        "value": "[[10->1]]"
                    }
                }
            ],
            ...
        }
}
```

**200->500** means that the value will be generated from 200 to 500 (by using the exponential function)

#### Reporting method

There are two options how to generate and collect VES events:

- FILE_READY collects events by each CellId and send those events as FileReady event together with generated PM Bulk XML File.
- VES sends each Ves event directly to VES Collector for processing

### A1-P Mediator API

The A1 Mediator listens to the northbound interface of the RIC for policy guidance.
The caller (e.g., non-RT RIC, SMO, etc.) creates policy types and policy instances through A1, and subsequently A1 exchanges messages with xApps via RMR.

#### Policy Type

Example schema (used in Policy Enforcement PoC):

```json
{
  "name": "samsung_policy_type",
  "description": "samsung policy type; standard model of a policy with unconstrained scope id combinations",
  "policy_type_id": 1000,
  "create_schema": {
    "$schema": "http://json-schema.org/draft-07/schema#",
    "title": "Samsung_demo",
    "description": "Samsung demo policy type",
    "type": "object",
    "properties": {
      "scope": {
        "type": "object",
        "properties": {
          "ueId": {
            "type": "string"
          },
          "groupId": {
            "type": "string"
          }
        },
        "additionalProperties": false,
        "required": [
          "ueId"
        ]
      },
      "resources": {
        "type": "array",
        "items": {
          "type": "object",
          "properties": {
            "cellIdList": {
              "type": "array",
              "minItems": 1,
              "uniqueItems": true,
              "items": {
                "type": "string"
              }
            },
            "preference": {
              "type": "string",
              "enum": [
                "SHALL",
                "PREFER",
                "AVOID",
                "FORBID"
              ]
            }
          },
          "additionalProperties": false,
          "required": [
            "cellIdList",
            "preference"
          ]
        }
      }
    },
    "additionalProperties": false,
    "required": [
      "scope",
      "resources"
    ]
  }
}
```

Required policy type can be created as follows:

```
curl -X PUT -v -H "accept: application/json" -H "Content-Type: application/json" --data-binary @/tmp/policy_type.json localhost:9998/v1/a1-p/policytypes/1000
```

where:

- @/tmp/policy_type.json file with policy schema
- localhost:9998/v1/a1-p/policytypes/${policy_type_id} - policy type ID (defined by client) used to create the policy type

#### Create/Delete Policy Instance

Create/update example policy instance request for given policy type:

```
curl --location --request PUT 'http://localhost:9998/a1-p/policytypes/1000/policies/1' \
--header 'Content-Type: application/json' \
--data-raw '{
  "scope" : {
    "ueId" : "emergency_samsung_s10_01"
  },
  "resources" : [
    {
      "cellIdList" : [ "Cell1" ],
      "preference" : "AVOID"
    }
  ]
}'
```

where:

- localhost:9998/a1-p/policytypes/${policy_type_id}/policies/${policy_instance_id} - policy instance ID (defined by client) used to create the policy instance

Delete the policy instance request of a given policy type:

```
curl --location --request DELETE 'http://localhost:9998/a1-p/policytypes/1000/policies/1'
```

### Run A1 PE Simulator with a new configuration

A1 PE Simulator uses the properties to define the following:

- File locations of vnf.config, cells.json, ue.json files
- VES consumer's supported protocol and endpoint (e.g. for VES-Collector)
- Cell range
- Default VES event sending interval
- Version of the A1 PE Simulator API
- FTP server connection and configuration
- FileReady event constants
- PM Bulk File constants

See (src/main/resources/application.properties) for default values.

The default values can be overridden in multiple ways:

#### 1. By defining the OS env variables

- VNF_CONFIG_FILE=
- TOPOLOGY_CELL_CONFIG_FILE=
- TOPOLOGY_UE_CONFIG_FILE=
- VES_COLLECTOR_PROTOCOL=
- VES_COLLECTOR_ENDPOINT=
- VES_DEFAULTINTERVAL=
- RESTAPI_VERSION=
  FTP_SERVER_UPLOAD=
- FTP_SERVER_PROTOCOL=
- FTP_SERVER_FILEPATH=
- FTP_SERVER_UPLOAD=
- XML_PM_LOCATION=

#### 2. By adding the process arguments

Add -D flag to the execution command:

- "-Dvnf.config.file="
- "-Dtopology.cell.config.file="
- "-Dtopology.ue_config.file="
- "-Dves.collector.protocol="
- "-Dves.collector.endpoint="
- "-Dves.defaultinterval="
- "-Drestapi.version="
- "-Dftp.server.upload="
- "-Dftp.server.protocol="
- "-Dftp.server.filepath="
- "-Dftp.server.upload="
- "-Dxml.pm.location="

When running with -Dspring.profiles.active=dev default values for **vnf.config.file**, **topology.cell.config.file** and **topology.ue.config.file** are set to use the example files from *src/test/resources/*

### FTP upload or file copy

In case of FILE_READY Reporting method, simulator creates PM Bulk File on FTP server in 2 ways:

- FTP upload - ftp.server.upload=true - uploads file using FTP connection.
- Copy file - ftp.server.upload=true - copy file to FTP file location using operating system. File location is specified by *xml.pm.location* property

### Refresh the configuration files on runtime

If the contents of cells.json or ue.json are changed, the user should send a request to A1 PE Simulator to reload those files:

```
curl --location --request GET 'http://localhost:9998/v1/ran/refresh'
```

Also, A1 PE Simulator automatically refreshes the topology/ues information from those files in defined time interval:

**refresher.fixed.rate.ms=60000**

## API

The API is documented by the Swagger tool.

### Swagger

The generated swagger html file can be found in *doc/swagger/html* directory.
JSON file that can be imported to Swagger GUI can be found in *doc/swagger*.
Those files are regenerated in each maven build, so to generate this file please see **Build the A1 PE Simulator** chapter.

## Developer Guide

### Build the A1 PE Simulator

Following mvn command (in the project directory) will build A1 Policy Enforcement Simulator:

```bash
mvn clean install
```

### Run the A1 PE Simulator

Following command will run the A1 Policy Enforcement Simulator:

```bash
java -jar a1-pe-simulator-1.0-SNAPSHOT.jar org.onap.a1pesimulator.A1PolicyEnforcementSimulatorApplication
```

The application should start on 9998 port.

### Logging

The logs file will be created in the ${user.home}/log path.
To define the **user.home** value, use the process arguments e.g "-Duser.home=/path_to_dir".

After the A1 PE Simulator starts successfully the */path_to_dir.log* should start to contain the logs:

```
.
└── a1-pe-simulator
    ├── application
    │        ├── debug-2021-03-15.0.log
    │        ├── error-2021-03-15.0.log
    │        └── metrics-2021-03-15.0.log
    └── debug-2021-03-15.0.log
```