miketsukerman / vsc-tools

Tools for processing Vehicle Service Catalog files, see https://github.com/COVESA/vehicle_service_catalog and compare also vss-tools: https://github.com/COVESA/vss-tools

Interface Exchange framework (IFEX)

This repository includes:

1. Specifications and documentation
2. Programs and tools

...for the the Interface Exchange framework (IFEX).

IFEX is a general interface description and transformation technology which started in the Vehicle Service Catalog (VSC) project. The technology (IFEX) is now developed under a separate name to better describe its purpose and that it is widely and generally applicable. (This repository was previously named vsc-tools)

Please refer to the documentation for more information.

IFEX software tools

Some of the programs generate the IFEX interface model/language-specification and other documentation. Other programs implement the tools for reading/writing/translating interface descriptions and code-generation.

The implementations are primarily written in python and using some preferred technologies, such as the Jinja2 templating language ((alt. link)).

Getting started

Prerequisites

• Python >=3.10 installed (exact version might vary - the best definition of what works is likely the automated workflow files
• Dependencies installed according to instructions below

Project Setup

• If you use a custom pip installation directory, set the PYTHONPATH environment variable to the directory that you set in the pip.ini file.

Setup with virtualenv

python3 -m venv venv
source venv/bin/activate

Setup with pipenv

pipenv is a tool that manages a virtual environment and install the package and its dependencies, making the process much simpler and predictable, since the Pipfile states the dependencies, while Pipfile.lock freezes the exact version in use.

(alternative) setup with pyenv

If pyenv shell command is not installed, use its installer to get it:

   curl https://pyenv.run | bash  # download and install
   exec $SHELL                    # restart your shell using the new $PATH

NOTE: In the following instructions, you might have to adjust the exact python version. See prerequisites.

Make sure Python version 3.10.6 is installed:

   pyenv install 3.10.6  # install the versions required by Pipfile

Activate a virtual environment

pyenv local 3.10.6

Installing packages

(regardless of which venv tool you use)

Install the IFEX provided modules into your virtual environment)

python setup.py develop

Install dependencies:

pip install pyyaml jinja2 pytest anytree

(Alternatively, we are providing a requirements.txt file but it might be deprecated later in favor of pipenv):

pip install -r requirements.txt

Setup with pipenv (alternative)

DEPRECATED / currently not working (We would welcome if you investigate it, and provide an updated instructions)

pipenv is a tool that manages a virtual environment and install the package and its dependencies, making the process much simpler and predictable, since the Pipfile states the dependencies, while Pipfile.lock freezes the exact version in use.

Install this project and its dependencies in the local .venv folder in this project, then use it (pipenv shell):

   export PIPENV_VENV_IN_PROJECT=1 # will create a local `.venv` in the project, otherwise uses global location
   pipenv install --dev # install the development dependencies as well
   pipenv shell         # starts a shell configured to use the virtual environment

Setup using plain pip install

Run from the vss-tools project root directory

   pip install -r requirements.txt

Setup without virtual environment (not recommended)

To install to your system environment:

pip install -r requirements.txt
python setup.py develop

Trying it out

Work in progress! This is the usage pattern:

   ifexgen <input-yaml-file (path)> <output-template-file (name only, not path)>

For the moment, try this:

   git clone https://github.com/COVESA/vehicle_service_catalog

   ifexgen vehicle_service_catalog/comfort-service.yml simple_overview.tpl

Installing the IFEX tools using setup.py also creates some convenient executable shims, e.g. ifexgen:

Example:

ifexgen input.yaml template.tpl

The comfort-service example above exercises the parser to create the AST out of a YAML file from the Vehicle Service Catalog definition, and then prints out an overview using the template.

^^^ Edit the code if you want to try out other things. This will soon be more flexible of course.

Looking at the jinja2 template shows how to traverse it directly by referencing each object's public member variables (see template simple_overview.tpl).

Unit Tests

The project uses pytest to define unit tests. In the tests directory is a simple starting point. More can be added.

To run tests, just run pytest in the root directory.

   pytest -v

Writing a generator

Simple Generator

A simple generator (with only one template) can be done like this:

• Import the ifex_generator.py and ifex_parser.py modules
• Get the Service description file (YAML), for example from command line argument
• Get the Abstract Syntax Tree representation by calling ifex_parser.get_ast_from_file(service_desc_file)
• Call gen() function in generator module, and pass the AST, and the name of a single template.
• If needed, add any of your own custom logic (see also advanced usage for more information)

Unless you need to add more logic, generating one input file with a single template is basically already available if ifex_generator.py is called as a main program:

   ifexgen <service-description.yml> <jinja-template-name>

NOTE: Due to how jinja loads templates (without adding a custom loader, which has not been done), the first argument is the path to the YAML file, but the second argument is only the name of the template (which must be in ifex/templates/ directory. Pointing to the full path of a template file in a different location is not implemented in ifex_generator.py

Advanced Generator

An advanced generator (with several templates) can be done like this:

• Import the ifex_generator.py and ifex_parser.py modules

• Get the needed Service description file(s) (YAML), for example from command line argument

• For each file, get the Abstract Syntax Tree representation by calling ifex_parser.get_ast_from_file(service_desc_file)

• Write templates according to (some, not all) node types. You can call gen(node) or gen(node, <Template>) from within a template - see details below.

• Set the default_templates member variable in generator to configure which templates to use (see section below).

• Implement the gen() function, normally by delegating directly into ifex_generator.gen(), but you can put your own logic here if needed.

• Call the gen() function with the topmost node. Store result in appropriate file.

• Continue calling the gen() function with another node, and another template for another file (for example, generating .c and .h header files from the same input)

• ... implement any other required logic in the generator code, and/or with the advanced control options available in jinja2 templates.

• NOTE! Remember to inject any globals (e.g. functions) into the jinja environment if these are referred by the templates. See ifex_generator.py for example. You can also pass data into templates through other variables (see jinja2 documentation).

Setting up default templates

This setting is a dictionary mapping the AST node types to the default template to use for that node type. It can be overridden in a call to gen() but for a particular code generation purpose it is better to set this up.

generator.default_templates = {
   'AST' : 'AST-mystuff-toplevel.txt',
   'Service' : 'Service-mystuff.c',
   'Type' :    'Type-mystuff-smart_type_mapper.c',
   'Method' :  'Method-mystuff.c'
}

NOTE: It is not required to specify a separate template for every type. Very often, nodes can be generated directly from the parent template type. For simple cases, a single top-level template might suffice for the whole generation.

The gen() function

The gen() function has a short name to be convenient in templates.

You can call the gen() function from within a template to delegate the required work for generating a certain node type to a separate template file. (See Template example later). Thus the templates can effectively "call" each other, without the need for template-include or template-inheritance features that jinja2 provides (but those features are of course still possible to use).

gen() can be called with (1) just the node (evaluating the passed parameter type at run-time) or (2) by explicitly stating a template:

1. Providing the node reference only:

def gen(node : AST)

example use:

gen(node)

This variant will dynamically determine the node type (a subclass of AST) and generate using the predetermined template for that node type. (See default_templates variable).

2. Providing the node and a specific template. The specified template is used regardless of the node type:

def gen(node : AST, templatename : str)

example use:

gen(node, 'My-alternative-method-template.tpl')

Writing Templates

Naming convention

Templates must be stored in the ifex/templates/ directory.

Templates should be named using this convention:

<node-type>-<target-format>-<variant>.<suffix>

• node-type must be the exact name of the corresponding class in the AST, e.g. Service, Method, Type, etc. A template that consumes the top-level root node would use the node type AST.
• target-format is a free form name for whatever it is you are generating
• variant is optional and just to indicate there might be multiple ways to generate the same thing for the same target. Basically, use your own judgement to name the template with useful information here.
• suffix should try to mimic the normal suffix for the file format that is being generated. For example, if the templates aims to generate a HTML document, name the template with .html. If it is generating a programming language, use an appropriate suffix for the file, etc. If there is no obvious type, we use ".tpl".

Examples:

Datatypes-my_docs-simple.html
Datatypes-my_docs-advanced.html
Method-c++-without-comments.cpp
Method-c++-with-comments.cpp
Service-nodejs.js
Service-rust.rs

Variable use in templates

• The standard functions in ifex_generator.py will pass in only a single node of AST type to the template generation framework. (If you define your own custom generator, it could choose to do something different).

The passed node and will have a particular node type (subclass to AST). The type depends on what type of template is being rendered (or more correctly, what was specified when the generation function was called -- either a top level function like render_ast_with_template_file() or a call to gen() with the node in question as parameter.)

• When using the provided generator convenience functions, the node that is "passed to the template" (roughly speaking) will always be named item

• The class member variables (referring to the children of a node) in all AST nodes are public. This means they can be referenced directly through dot-notation inside code that is embedded in the jinja template. For example, if the passed item is a Service the template can get to the list of namespaces in the service by just referencing it: item.namespaces

This of course means that dot-notation could also be chained: item.namespaces[1].methods[0].description - the description of th efirst method name in the second namespace.

It is however more likely to use loop constructs to iterate over lists than to address specific indexes like that:

{% for i in item.namespaces %}
   this is each namespace name: {{ i.name }}
{% endfor %}

Advanced features

jinja2 is a very capable templating language. Generators can make use of any features in python or jinja2 to create an advanced generator. Any features that might be applicable in more than one place would however be best generalized and introduced into the ifex_generator.py helper module, for better reuse between custom generator implementations.

Template example

This template expects that the "item" passed in is a Service object. It calls the gen() function from within the template to delegate work to a separate template for Methods.

Service-mygen.c

// General file header information
// ...

// Service name: {{ item.name }}

{% for i in s.namespaces %}
// namespace: {{ i.name }}
// {{ i.description }}
{% for x in i.methods %}
  {{ gen(x) }}     <- delegate work to a separate template for Methods
{% endfor %}
{% endfor %}

The gen() function in the ifex_generator implementation will determine the node type of x at runtime, yielding Service. It will will then look into the default_templates variable to see which is the template file to use for a Service node, and generate the node using that template.

The global default_templates variable is defined by ifex_generator to point to some templates used for test/demonstration. A custom generator implementation would modify this variable, or simply overwrite the value after including the ifex_generator as a module (or later on, this might be passed in at run-time in a different way).

Existing Tools/Templates

Template	Description	Status	Documentation
dtdl.tpl	Generates a DTDL description of the service	Functional	documentation
protobuf.tpl	Generates a Protobuf description of the service	Functional	documentation
sds-bamm-aspect-model.tpl (using sds-bamm-macros.tpl)	Generates a BAMM Aspect Meta Model of the service	Functional	documentation
test.tpl	Dummy Example	Not Functional	-
AST-simple_doc.tpl	Very simple HTML generator, relying on Service-simple_doc.html	Not Functional	-
simple_overview.tpl	Generates a textual overview of a service	Functional	-
Argument-simple_doc.html	Default template for arguments	Not Functional	-
Service-simple_doc.html	Default template for services	Not Functional	-

Future plans, new proposals and enhancements

Please refer to GitHub tickets (Feel free to make a proposal or ask a question)

Known bugs

Please refer to GitHub tickets with the label "bug"

Troubleshooting

Various tips to consider:

• If the installation (pip install) is executed behind a (corporate) proxy, the following environments variables must be set: http_proxy and https_proxy (including authentication e.g., http://${proxy_username):$(proxy_password)@yourproxy.yourdomain)
• If you do not run with administration rights, you may need to configure pip target path to write to your user home directory or consider using one of the virtual environment methods.