Support POST requests

[evandrocoan]

Because GET requests have a char length limit

from urllib.parse import urlencode
from urllib.request import Request, urlopen

url = 'http://localhost:8080/plantuml/post'
post_fields = {'source': r'@startuml\na --> b\na <-- b\n@enduml'}

request = Request(url, urlencode(post_fields).encode())
answer = urlopen(request).read().decode()
print(answer)

Would be useful for internal application as:

1. https://github.com/qjebbs/vscode-plantuml
2. https://github.com/pkucmus/sublime-plantuml

With this they can render the images much faster and can handle big diagrams:

Plugin supports two renders: Local and PlantUMLServer.

Local is the default and traditional way. If you care more about export speed, you should try PlantUMLServer.

Local: 6 documents, 9 digrams, 14 files exported in 24.149 seconds
PlantUMLServer: 6 documents, 9 digrams, 14 files exported in 1.564 seconds

[llaville]

Hello,

I used the docker image from latest tag (December 22, 2018) with POST feature supported, but with a huge source code, i got such result :

Bad Message 431
reason: Request Header Fields Too Large

is there a solution to fix such situation ?
Thanks in advance

[HeinrichAD]

For documentary reasons: It is possible to send the diagram text/code as body via post request to get the desired response.
See examples here: #67 (comment)

About the second issue:

Bad Message 431
reason: Request Header Fields Too Large

I can not really reproduce the error with the current version v1.2023.8. If the issue is still valid, please open a separate issue including an example how to reproduce it. Please also check/include what you exactly write into the request header fields.