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1.  For external interface

    After the tosca parser microservice is implemented, the Lib usage will continue to be provided, and the application can select to use  the microservice or the Library according to the specific requirements scenario

   
   

2.  For Parser implementation

   
   

   1. Requirement Analysis ( which is tracked in SDC Template Type Analysis): collecting requirements, unifying model input and output, simultaneously implementing model output conversion from object to Json (this is the key point)

   2. API Incapsulation: Providing unified restful interface to parser client. 

      For parser API abstraction，there are two options considered

      Option	Description	Advantage	Disadvantage
      1	Parser only provides one

      naive

      simple API with the csar file as input and return complex Object which contains all content in model API may looks like: ModelObject parseCsar( csarfile)

      The parser implementation is relatively simple， just focus on how to build the complex response

      Client need to extract the information that they need from complex response

      locally，will

      locally，this will bring more complexity on client side

      2

       Parser

      Parser provides the extension APIs which are more

      fine-grained

      granular and return the specific content in model to client according to different API invocation These APIs may look like: Metadata getServiceMetadata(InputParameter) Inputs getInputs(InputParameter) ......

      Don’t need to maintain two library code and can solve cross-language issue.

      Parser should keep the context information and increase the difficulty of parser implementation

      
      

      
      

      
      

Supplement

In order to analysis the tosca parser requirements, we do some analysis on the tosca types which currently included and used in SDC and the analysis can be found here: SDC Template Type Analysis

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