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List some projects as an example::

Here only list part of the projects, not all the parser consumer project.

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Advantages of Parser as a Microservice

1.  Microservice

   Microservice can be decoupled from

   applications

   applications 

   Effect: The application does not need to know the implementation details of the Passer, only need to pay attention to the results of the analysis.

   Current status: As a Library, an application can use parser only after understanding the internal implementation of Parser.
   
   

2.  Multi-language support

   Effect: Parser provides services through restful, language-independent, and can support any language such as python and java. Current

   Current Status: There are different Parser tools for different languages, and cross-language support is difficult.

   
   

3.  Easy Easy to upgradeupgrade 

    EffectEffect: Parser upgrades independently, only keep the external restful interface unchanged. 

    Current Current Status: The current Parser as Library, the application sees the internal implementation details of Parser, if Lib upgrade, it will affect the application.
   
   

4.  Easy to deploy, support horizontal expansion

    Current Status: With the application deployment, it is not easy to support horizontal expansion, and there is basically no flexibility.

    Effect: After Parser is as a service, it conforms to Cloud Native idea, can utilize platform advantages, flexible deployment, and horizontal expansion. Current Status: With the application deployment, it is not easy to support horizontal expansion, and there is basically no flexibility.

 Disadvantages of Parser as a microservice

1.  Performance: Compared with the Lib usage, when Parser provides services through restful, the performance will be reduced 

   
   

2.  DelayDelay: Compared with the Lib usage, when Parser provides services through restful, the delay will increase increase

   
   Note： Temporarily there is no data support for  the above performance and delay 

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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 implementationThe first phase：

   
   

   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)

   In the second stage：

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

R3 CSAR which exported by SDC in CCVPN use case and CPE use case 

vCPE：

CCVPN:

1. 1.  

      For parser API abstraction，there are two options considered

      Option	Description	Advantage	Disadvantage
      1	Parser only provides one 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，this will bring more complexity on client side
      2	Parser provides the extension APIs which are more 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

Known TOSCA Parsers

See the list on this TOSCA page

Discussion Minutes (20190102)

• Agreement: SDC Type fix ABC for Dublin
• Target: Parser as a service
• Problem: Rest API definitions for Parser us
• Next Steps:
  • Parser API analysis for run time consumers;
  • Brain Storming in Paris for Parser API design.

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