A tool to model and analyze the design of systems from java class files.

sift spring-boot axon framework demo

Spring-Boot with Axon Framework instrumenter in action.

Entity and Entity Type

The system model is described by its constituent entities and their relationships. Each entity is uniquely identified by either a class, method, field or parameter element; an element can not be associated with more than one entity.

All entities are mapped to a type. A type represents any notable part of the system, e.g. REST controllers, HTTP endpoints, inbound/outbound messages, RDS etc.

$ sift --instrumenter spring-axon --list-entity-types target/classes
entity types of spring-axon
  1 aggregate
  2 aggregate-ctor
  1 aggregate-member
  6 command
  6 command-handler
  1 controller
 13 endpoint
  7 event
  7 event-handler
  7 event-sourcing-handler
  1 projection
  3 query
  4 query-handler

Instrumenter pipelines

Instrumenter Pipelines are responsible for producing the system model from input classes. Pipelines are written in a declarative DSL, which provides high-level abstractions for identifying and interrelating entities from class structure or usage.

val controller = Entity.Type("controller")
val endpoint = Entity.Type("endpoint")

instrumenter {
    // iterate over all input classes
    classes {                                                      
        annotatedBy<RestController>() // filter classes 
        entity(controller)            // mark remaining as 'controller'  
        methods {                     // iterate all controller methods
            annotatedBy<Endpoint>()   // filter @Endpoint methods

            // associate controllers with their endpoints  
            controller["endpoints"] = endpoint

Input elements – classes, methods, parameters and fields – are processed in batch, line-by-line.

A Instrumenter Pipeline can be expressed in about 100LOC. Some are notably shorter, e.g. jpa and jdbi. Any pipeline can be included by user-defined pipelines using include(pipeline).

The execution of an Instrumenter Pipeline can be visualized with --profile:

sift spring-boot axon framework demo


Caveats and limitations

  • no flow control


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