Jolie Slicer

Jolie Slicer is the companion tool to the Sliceable Monolith¹ development methodology.

The tool (jolieslicer) is available on npm:

npm install -g @jolie/slicer

Usage:

jolieslicer <monolith.ol> -c <slicer.json> [--slice <output_directory> | --simulate <service_name>]

Sliceable Monolith

1. The entire microservices architecture is coded in a single Jolie file (monolith.ol):

   1. Services are parameterised by their deployment configuration (config)
   2. Input and Output ports are parameterized by their deployment location available under the path config.ServiceName.locations._

   As an example:

   service Gateway( config ) {
     inputPort ip {
       location: config.Gateway.locations._[0]
       ...
     }
     outputPort CommandSide {
       location: config.CommandSide.locations._[0]
       ...
     }
     main { ... }
   }

2. A configuration file (slicer.json) describes the services in the architecture and their ports:

   {
     "Gateway": {
       "params": {},
       "ports": [
         8080
       ]
     },
     "CommandSide": {
       "params": {},
       "ports": [
         "internal"
       ]
     },
     ...
   }

   Services provide their functionality through one or more ports, each declared as either:

   • Internal ("internal") and accessible only by services in the same deployment
   • Exposed (e.g., 8080) and accessible by external clients through a TCP socket

3. The Jolie Slicer can now be used to either:

   1. Run the microservices architecture as a single executable by specifying the name of the service that acts as the entry point of the application:

      jolieslicer monolith.ol -c slicer.json --simulate Gateway

   2. Slice the monolith into separate codebases, one for each service mentioned in the configuration (slicer.json):

      jolieslicer monolith.ol -c slicer.json --slice <output_directory>

      and a reasonable docker-compose configuration for the distributed deployment of the architecture:

      cd <output_directory> && docker compose up

Example

An example is provided under example/:

• monolith.ol implements a Sliceable Monolith
• slicer.json is the Slicer configuration
• microservices/ contains the result of slicing the monolith

From within the direcotry example, one can:

• Run the monolith as a single executable:

  jolieslicer monolith.ol -c slicer.json --simulate Main

• Run the service Test to locally execute an integration test:

  jolieslicer monolith.ol -c slicer.json --simulate Test

• Slice the monolith into separete codebases:

  jolieslicer monolith.ol -c slicer.json --slice microservices

Footnotes

1. Sliceable Monolith: Monolith First, Microservices Later ↩