Virtualizing gRPC Service

Install devtool

Install the npm cli tool. Make sure npm module in on system path by running a command.

Initialize project

• Go to projejet directory and run grpc init.
• Enter an output path
• Enter path containing proto files
• Choose files to create default mappings for
• There is a new directory created in project.

Check created grpc.yaml

• This is the file with default values

• All these values can be overrided using command line parameters

• grpc.yaml

  # Address for our server
  host: 'localhost'
  port: '3009'
    
  # We will add adress of real service here
  remoteHost: 'localhost'
  remotePort: '3010'
    
  # Relativ path to any other folder containing our proto files
  protos: ../protos
    
  # While recording sreams, it will save only 10 messages by default
  trimmedStreamSize: 10
  

Check created mappings.yaml and default repsonses

• It created a mapping.yaml file as

  iit.paas.services.fx.FxAutoQuote.GetPrice:
    - data/GetPrice/default.yaml
    
  iit.paas.services.fx.FxAutoQuote.GetPriceStream:
    - data/GetPriceStream/default.yaml
    
  iit.paas.services.fx.FxAutoQuote.GetIncrementalPriceStream:
    - data/GetIncrementalPriceStream/default.yaml
  

• And corresponding templates that can return some values for eny endpoint :

  request@ : {
    "uic": "@any",
    "spread_set_id": "@any",
    "commission_group_id": "@any",
    "client_class_id": "@any",
    "liquidity_factor_option": "@any",
    "amount": "@any",
    "order_price": "@any",
    "trade_history_amount_option": "@any",
    "accumulated_amount": "@any",
    "buy_sell": "@any",
    "order_type": "@any",
    "order_duration": "@any",
    "field_ids": "@any"
  } 
    
  response@ : {
    "field_values": ["2.3"]
  }
  

Configure app to use devtool server

• Change the address of remote service in app to use our grpc-devtool server

    "ServiceSettings": {
  -   "gRPCServer": "DEVTCE1-DK1.sys.dom",
  +   "gRPCServer": "localhost",
  -   "gRPCPort": 7903,
  +   "gRPCPort": 3009,
    }
  

• Also in grpc.yaml set the address of our real service. The devtool will use it to record from remote service.

    host: 'localhost'
    port: '3009'
    
  - remoteHost: ''
  + remoteHost: 'DEVTCE1-DK1.sys.dom'
  - remotePort: ''
  + remotePort: '7903'
    
    protos: ../protos
    trimmedStreamSize: 10
  

Record gRPC interactions

• Go to our project and run devtool in record mode

  cd Stub
  grpc record .
  

• Make an API call in the app

Map recorded files

• New files are created in devtool folder under recorded@
• Rename and organize these files as per your preferences
• Update the mapping.yaml to map them to endpoints

Run service against devtool server

• No stop the recorder and start devtool in server mode

  grpc serve .
  

Thats it ! Now our app is running against fixed data. Check out the streaming API. It returns the same set of elements circularily.