wsgi-on-cafebabepy-plone-conf-2018

cafebabepy is yet another Python 3 implementation written in Java that runs on JVM.

This session explains how to run WSGI on cafebabepy.
You can better understand WSGI by knowing how to implement it on cafebabepy.

Transcript

1. WSGI on cafebabepy Plone Conference 2018 Tokyo November 8, 2018 yotchang4s (Yoshiaki Shibutani)
2. Who am I? ❖ Yoshiaki Shibutani (澁谷 典明) ➢ yotchang4s (よっちゃん) https://twitter.com/yotcang4s ❖ Python usage history ➢ I've been using Python for 1 year and 6 month. ❖ Work ➢ I am programming with Scala.
3. What will I talk about in this session? This session explains how to run WSGI on cafebabepy. You can better understand WSGI by knowing how to implement it on cafebabepy.
4. Table of contents 1. What is cafebabepy? 2. What is WSGI? 3. WSGI on cafebabepy 4. DEMO 5. In closing
5. What is cafebabepy?
6. Overview of cafebabepy cafebabepy is yet another Python 3 implementation written in Java that runs on JVM. The name of cafebabepy comes from cafebabe which is the magic number of the Java class file. I've been developing cafebabepy for 1 year and 6 months. I am still developing cafebabepy. cafebabepy does not work perfectly as Python 3...
7. Start Python 3! 1. Let's use Jython! 2. Jython does not support Python 3... 3. and Jython has not been updated since 2015… 4. If so...
8. I make it!
9. Motivation I am a Python beginner. I could not write Python. If I make a Python implementation, I should be able to write Python! It's so much fun!! ＼(^o^)／
10. What is WSGI?
11. Overview of WSGI WSGI is Web Server Gateway Interface. WSGI is defined in PEP 333 and PEP 3333. WSGI is a standard interface for connecting Web server and Web application.
12. Why is WSGI necessary? Before the WSGI was created, Web server that Web application can use was different. Because it was implemented in various ways such as mod_python and CGI. Therefore, WSGI was created. WSGI solved the problem in Python by defining standard specifications for connecting Web application and Web server.
13. PEP 333 PEP 333 is the specification of WSGI made for Python 2. However, there was a problem due to Python 3 specification change. It's because Python 3 changed the handling of string and binary. In WSGI, HTTP response body is binary.
14. Python 2 and Python 3 strings and binaries ❖ Python 2 ➢ string: unicode ➢ binary: str ❖ Python 3 ➢ string: str ➢ binary: bytes
15. PEP 3333 PEP 3333 update PEP 333. It's for Python 3. In Python 3, the Unicode string is 'str' and the binary is 'bytes'. String and binary are separated in Python 3. Therefore, PEP 3333 defined the response body as 'bytes'.
16. WSGI application example hello_world.py def app(environ, start_response): start_response("200 OK", [ ('Content-type', 'text/plain') ]) return [b"Hello World"]
17. server (Apache/Nginx/etc…) Structure of WSGI (example) WSGI application container app function hello_wsgi.py This interface is WSGI.
18. WSGI application example hello_wsgi.py def app(environ, start_response): start_response("200 OK", [ ('Content-type', 'text/plain') ]) return [b"Hello"]
19. WSGI application example hello_wsgi.py def app(environ, start_response): start_response("200 OK", [ ('Content-type', 'text/plain') ]) return [b"Hello"]
20. hello_wsgi.py def app(environ, start_response): start_response("200 OK", [ ('Content-type', 'text/plain') ]) return [b"Hello"] WSGI application example
21. WSGI on cafebabepy
22. WSGI on cafebabepy Java comes in from here. cafebabepy can not handle 'wsgiref' module. Therefore, cafebabepy on the Java Servlet and realizes the WSGI specification. Java Servlet is a specification that runs Web applications in Java.
23. Jetty(Servlet container) Structure of WSGI on cafebabepy WSGIServlet app function hello_wsgi.py cafebabepy
24. Flow in which WSGIServlet is executed 1. cafebabepy initialize. 2. GET, POST etc. request from client. 3. doGet, doPost, doHead, doTrace, doPut, doDelete and doOptions method is executed. 4. Run the WSGI application endpoint with cafebabepy. 5. Make the result of executing the WSGI application a response.
25. Make environ hello_wsgi.py def app(environ, start_response): start_response("200 OK", [ ('Content-type', 'text/plain') ]) return [b"Hello"]
26. Make environ dict Create a environ dict with WSGIServlet for cafebabepy. WSGIServlet get the request from the client and put it into environ dict.
27. Create environ dict in Java code WSGIServlet.java private PyObject getEnviron(HttpServletRequest req) { LinkedHashMap<PyObject, PyObject> environ = new LinkedHashMap<>(); environ.put(this.runtime.str("REQUEST_METHOD"), this.runtime.str(req.getMethod().toUpperCase())); ... return this.runtime.dict(environ); }
28. Make start_response start_response is callable. This is the requirement. 1. Call start_response from the WSGI application. 2. WSGIServlet holds arguments of start_response called from the WSGI application. WSGIServlet then passes it to the servlet's response. To satisfy these two In WSGI on cafebabepy, start_response is Python code.
29. Python code to create start_response① cafebabepy/wsgi.py class Server: def __init__(self): self._status = None self._response_headers = [] def start_response(self, status, response_headers, exc_info=None): self._status = status; self._response_headers = response_headers @property def status(self): return self._status
30. Python code to create start_response② cafebabepy/wsgi.py @status.setter def status(self, status): self.status = self._status @property def response_headers(self): return self._response_headers @response_headers.setter def response_headers(self, response_headers): self._response_headers = response_headers
31. Call WSGI application endpoint WSGI on cafebabepy calls the endpoint of the WSGI application. The arguments are environ and start_response.
32. Set endpoint of WSGI application @WebServlet(name = "Hello Plone Conf", urlPatterns = {"/*"}, initParams = { @WebInitParam( name = InitParam.MODULE, value = "hello_plone_conf" // WSGI Application module ), @WebInitParam( name = InitParam.FUNCTION, value = "app") // WSGI Application endpoint }) public class HelloPloneConf2018WSGIServlet extends WSGIServlet { }
33. Initialize WSGIServlet public class WSGIServlet extends HttpServlet { @Override public void init(ServletConfig config) { String module = config.getInitParameter(InitParam.MODULE); String function = config.getInitParameter(InitParam.FUNCTION); this.runtime = Python.createRuntime(); PyObject context = this.runtime.evalModule(module); PyObject wsgiModule = this.runtime.evalModule("cafebabepy.wsgi"); this.server = this.runtime.getattr(wsgiModule, "Server").call(); this.startResponse = this.runtime.getattr( this.server, "start_response"); this.function = this.runtime.getattr(context, function); } }
34. When a request comes to WSGIServer① private void doXXXX(HttpServletRequest req, HttpServletResponse resp) 　throws IOException { PyObject environ = getEnviron(req); PyObject results = this.function.call(environ, this.startResponse); PyObject status = this.runtime.getattr(this.server, "status"); PyObject headers = this.runtime.getattr(this.server, "response_headers"); int statusCode = Integer.parseInt(status.toJava(String.class) .split(" ")[0]); resp.setStatus(statusCode); ...
35. When a request comes to WSGIServer② … this.runtime.iter(headers, header -> { PyObject[] keyAndValue = new PyObject[2]; int[] i = new int[1]; this.runtime.iter(header, kv -> keyAndValue[i[0]++] = kv); resp.setHeader( keyAndValue[0].toJava(String.class), keyAndValue[1].toJava(String.class) ); });
36. When a request comes to WSGIServer③ … OutputStream os = resp.getOutputStream(); try { this.runtime.iter(results, bytes -> { try { int[] ints = bytes.toJava(int[].class); for (int i : ints) { os.write(i); } } catch (IOException e) { throw new IOExceptionWrapper(e); } }); } catch (IOExceptionWrapper e) { throw e.e; } }
37. DEMO
38. DEMO WSGI application hello_plone_conf_2018.py def app(environ, start_response): start_response("200 OK", [ ('Content-type', 'text/plain; charset=UTF-8')]) return [ "Hello Plone Conf 2018 Tokyo!!\n" "こんにちはPlone Conf 2018 Tokyo！！" .encode("utf-8") ]
39. Run!!
40. In closing
41. In closing I explained why WSGI is necessary. I explained the specification of WSGI. I explained how to realize WSGI with cafebabepy. I will be glad if you understand the outline of the specification of WSGI by my explanation. I'm happy if you understand how to implement WSGI on cafebabepy. This is all for my session.
42. Let’s enjoy WSGI!!
43. Thanks for listening.
44. Any question?