---
-class: center, middle
+class: center, middle
+name: psgi-flow1
## Extremely High-level Overview
---
-class: center, middle
+class: center, middle
+name: psgi-flow2
## Pretty High-level Overview
---
-class: center, middle
+class: center, middle
+name: psgi-flow3
## Somewhat High-level Overview
---
-class: center, middle
+class: center, middle
+name: psgi-flow4
## Somewhat High-level Overview
---
-class: center, middle
+class: center, middle
+name: psgi-flow5
## High-level Overview
???
- A web framework makes it so your app doesn't need to speak HTTP or CGI or even PSGI.
- -
---
- New skills make you more marketable.
--
-- So that you it when you see PSGI exposed through your web framework.
+- So that you understand it when you see PSGI exposed through your web framework.
--
- You can do cool things with PSGI!
--
- The IETF and W3C took over standards development, resulting in [RFC 1945](https://tools.ietf.org/html/rfc1945) ("HTTP 1.0") in 1996.
+???
+- IETF = Internet Engineering Task Force
+- W3C = World Wide Web Consortium
+
--
- [RFC 2068](https://tools.ietf.org/html/rfc2068) ("HTTP 1.1") happened in 1997, superceded by [RFC 2616](https://tools.ietf.org/html/rfc2616) in 1999.
---
-.col[
+.col.marginfix[
### Request
```http
GET /ip HTTP/1.1
User-Agent: Mozilla/5.0 (X11; Linux x86_64)
-Host: foo.acme.tld
+Host: localhost
Accept-Language: en-us
Connection: Keep-Alive
```
]
-.col[
+.col.marginfix[
### Response
```http
HTTP/1.1 200 OK
Date: Thu, 07 Jul 2016 11:56:23 GMT
Server: nginx
-Content-Length: 30
+Content-Length: 29
Content-Type: text/plain
Connection: Closed
---
-.col[
+.col.marginfix[
### Request
```http
*GET /ip HTTP/1.1
User-Agent: Mozilla/5.0 (X11; Linux x86_64)
-Host: foo.acme.tld
+Host: localhost
Accept-Language: en-us
Connection: Keep-Alive
```
]
-.col[
+.col.marginfix[
### Response
```http
HTTP/1.1 200 OK
Date: Thu, 07 Jul 2016 11:56:23 GMT
Server: nginx
-Content-Length: 30
+Content-Length: 29
Content-Type: text/plain
Connection: Closed
---
-.col[
+.col.marginfix[
### Request
```http
GET /ip HTTP/1.1
*User-Agent: Mozilla/5.0 (X11; Linux x86_64)
-*Host: foo.acme.tld
+*Host: localhost
*Accept-Language: en-us
*Connection: Keep-Alive
```
]
-.col[
+.col.marginfix[
### Response
```http
HTTP/1.1 200 OK
Date: Thu, 07 Jul 2016 11:56:23 GMT
Server: nginx
-Content-Length: 30
+Content-Length: 29
Content-Type: text/plain
Connection: Closed
---
-.col[
+.col.marginfix[
### Request
```http
GET /ip HTTP/1.1
User-Agent: Mozilla/5.0 (X11; Linux x86_64)
-Host: foo.acme.tld
+Host: localhost
Accept-Language: en-us
Connection: Keep-Alive
```
]
-.col[
+.col.marginfix[
### Response
```http
HTTP/1.1 200 OK
Date: Thu, 07 Jul 2016 11:56:23 GMT
Server: nginx
-Content-Length: 30
+Content-Length: 29
Content-Type: text/plain
Connection: Closed
---
-.col[
+.col.marginfix[
### Request
```http
GET /ip HTTP/1.1
User-Agent: Mozilla/5.0 (X11; Linux x86_64)
-Host: foo.acme.tld
+Host: localhost
Accept-Language: en-us
Connection: Keep-Alive
```
]
-.col[
+.col.marginfix[
### Response
```http
*HTTP/1.1 200 OK
Date: Thu, 07 Jul 2016 11:56:23 GMT
Server: nginx
-Content-Length: 30
+Content-Length: 29
Content-Type: text/plain
Connection: Closed
---
-.col[
+.col.marginfix[
### Request
```http
GET /ip HTTP/1.1
User-Agent: Mozilla/5.0 (X11; Linux x86_64)
-Host: foo.acme.tld
+Host: localhost
Accept-Language: en-us
Connection: Keep-Alive
```
]
-.col[
+.col.marginfix[
### Response
```http
HTTP/1.1 200 OK
*Date: Thu, 07 Jul 2016 11:56:23 GMT
*Server: nginx
-*Content-Length: 30
+*Content-Length: 29
*Content-Type: text/plain
*Connection: Closed
---
-.col[
+.col.marginfix[
### Request
```http
GET /ip HTTP/1.1
User-Agent: Mozilla/5.0 (X11; Linux x86_64)
-Host: foo.acme.tld
+Host: localhost
Accept-Language: en-us
Connection: Keep-Alive
```
]
-.col[
+.col.marginfix[
### Response
```http
HTTP/1.1 200 OK
Date: Thu, 07 Jul 2016 11:56:23 GMT
Server: nginx
-Content-Length: 30
+Content-Length: 29
Content-Type: text/plain
Connection: Closed
1. Gateway sets information about the request in the environment.
-.condensed[
+.condensed.marginfix[
.col[
- `AUTH_TYPE`
- `CONTENT_LENGTH`
]
]
+???
+- In Perl, you can get these using %ENV.
+- Or getenv from stdlib.
+- If you've done some web programming before, you're probably familiar with at least a few of these.
+
---
```perl
1. Gateway sets information about the request in the environment.
2. Print response headers to `STDOUT`.
-.condensed[
+.condensed.marginfix[
.col[
- `Content-Type`
- `Location`
producing correctly-formatted headers, and even producing HTML.
- CGI.pm was deprecated in perl 5.20 and remove from core in perl 5.22.
-TODO make a slide for this
Good:
- Conceptually simple.
- Only requires the use of the most basic and primitive program constructs (stdin, stdout, env).
+- Only other primitive construct that could have been used is that of passing program arguments.
+ - Actually, the spec does specify behavior for "search-strings" as program arguments.
Bad:
- Details can get complicated.
???
- Unlike the interfaces we have examined so far, mod_perl is code.
+- About the same time as FastCGI.
--
- Became an Apache Software Foundation project at ApacheCon 1999 in Orlando.
```
???
-- There's a separate mod_perl for nginx.
+- Notice how we're not using STDOUT (or even pretending to).
+- This program actually runs on a perl interpreter inside the web server.
+- It also has access to more information through the exposed API.
Good:
- Can run CGI programs as-is.
Bad:
- Can tie you to specific web servers.
+ - There's a separate mod_perl for nginx.
- Code runs in the same process as the HTTP server -- kinda scary.
- Using Apache's API feels heavy.
};
```
+???
+- I think it's good to understand CGI et al. so that you can understand why it was designed the way
+ it was.
+- Hopefully the ideas behind PSGI are based off of the best that CGI et al. had to offer without any
+ of the drawbacks.
+
+
+- Notice how the program is a subroutine.
+- By being a subrouting rather than a script that is executed, we're already in a form that can be
+ called repeatedly without incurring fork-exec overhead. Nice!
+
---
```perl
1. Hashref of request information.
]
+???
+- Oh, look! The variable is the same as is specified by CGI.
+ - Why throw away over a decade of convention?
+
---
```perl
1. HTTP status code.
]
+???
+- Then you'll notice that instead of printing anything, we return an arrayref as the response.
+
---
```perl
---
+class: plack
+
## Plack
- Provides tools for building, running, and testing PSGI apps.
---
-.condensed[
+.condensed.marginfix[
.col[
- `HTTP_ACCEPT`
- `HTTP_ACCEPT_ENCODING`
---
-.condensed[
+.condensed.marginfix[
.col[
- .highlight[`HTTP_ACCEPT`]
- .highlight[`HTTP_ACCEPT_ENCODING`]
---
-.condensed[
+.condensed.marginfix[
.col[
- `HTTP_ACCEPT`
- `HTTP_ACCEPT_ENCODING`
## Thank you
Email me: Charles McGarvey
-<cmcgarvey@bluehost.com>
<chazmcgarvey@brokenzipper.com>
.talkqr.center[
]
]
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+</textarea><script src="https://gnab.github.io/remark/downloads/remark-latest.min.js"></script><script>var slideshow = remark.create({countIncrementalSlides: true, highlightLanguage: 'perl', highlightLines: true, ratio: '16:9', /*slideNumberFormat: '',*/ navigation: {scroll: false, touch: false, click: false}})</script><script src="js/common.js"></script><script src="js/slides.js"></script></body></html>
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