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Misc. Notes on WebPerl

TODOs

Testing
- How to best disable individual tests that we know won’t work? (qx etc.)
- How to handle the many tests that call an external Perl?
  - patching t/test.pl’s runperl() seems easiest at the moment, and we can use the iframe method from the IDE
- Continue work on WebPerl.t
  - More tests for Unicode support (Perl/JS interface, Perl.eval(), plus Emscripten’s virtual FS)
- Focus on getting the tests running in the browser instead of node.js
- How to best package tests?
  - If possible, a separate bundle, so that it can be loaded optionally and we don’t need to rebuild
  - How does make test find and handle all the various modules’ ts?
Misc
- Write up a full RPC example
- Future
  - Would Future::AsyncAwait work in WebPerl? (Or maybe with a JS backend?)
  - Future::HTTP (probably just as a frontend to XHR?)
- Improve Perl 6 integration
  - Build a packaged Rakudo.js ourselves instead of borrowing from https://perl6.github.io/6pad/
  - Perhaps get an API change or two into Rakudo.js: STDOUT currently gets output with HTML escapes
  - See also notes in Perl 6 Support 🦋
- Investigate Emscripten’s main loop concept for handling nonblocking sockets?
- Use Multiplicity for re-starting perl? (Thanks to Nick Clark for the idea)
- Add Regex::Debugger into regex tester? (Thanks to Renee for the idea)
- Turn some patches from emperl5 into patches for P5P
- Submit some patches to Emscripten
  - https://github.com/kripken/emscripten/pull/7005
  - https://github.com/kripken/emscripten/issues/7029
  - Would we need to patch Perl’s signal functions if Emscripten’s stubs weren’t noisy?
- Add Perl.Util functions for making file uploads and downloads easier
  - Plus an example showing how to use it to run a “legacy” Perl script with inputs and output
- There is some potential for restructuring:
  - Perl.glue() and Perl.dispatch() could go into WebPerl.xs (?)
  - Parts of webperl.js could go into common_preamble.js or WebPerl.xs, so that emperl.js is runnable on its own in a Web Worker (?) (see notes in perlrunner.html / e12f1aa25a000) → this might be interesting for running tests?!
  - nodeperl_dev_prerun.js could probably be merged into that as well
- Could put a WebPerl stub on CPAN
  - In theory could write a WebPerl::Local that contains the WebPerl API, and have various drivers such as WebPerl::WebDriver or WebPerl::JSAny that runs the code given to WebPerl’s js()…
- Regarding the funky syntax highlighting on GitHub: https://github.com/atom/language-html/issues/88#issuecomment-431361414
See Also
- https://github.com/haukex/webperl/issues
- https://github.com/haukex/webperl/pulls
- See also TODOs in the source tree by grepping for TODO or using the included findtodo.sh.

SSL

$ openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout selfsigned.key -out selfsigned.crt
...
Common Name (e.g. server FQDN or YOUR name) []: localhost
...
$ plackup --enable-ssl --ssl-key-file=selfsigned.key --ssl-cert-file=selfsigned.crt web/webperl.psgi
# then go to https://localhost:5000 and accept the certificate warning

Possible Improvements

More efficient JS/C/Perl glue
Test/Support sockets/WebSockets
- for example, can we compile a DBD:: module to connect to a DB on the server?
A RPC module for communicating between client and server Perls
- I think it’s probably best to not have WebPerl prescribe a specific RPC mechanism, since there’s a big variety and many are pretty simple to implement using e.g. jQuery
Support some of the Emscripten C API (like wget?)
Try to shrink the download size more (exclude more modules, …?)

Limitations

Only works in browsers with WebAssembly support (asm.js requires aligned memory access, and Perl apparently has quite a few places with unaligned access)
32-bit ints
No system, qx, fork, kill, wait, waitpid, threads, etc.
- Theoretically, we could link in BusyBox to get a shell and utilities (??)
- (system and qx support could theoretically be added by patching pp_system/pp_backtick in pp_sys.c)
No signals (except SIGALRM)
In the current configuration, exit is not supported, and therefore atexit handlers aren’t supported (see discussion in Using WebPerl, and NO_EXIT_RUNTIME in the Emscripten documentation - currently it seems to make the most sense to build with NO_EXIT_RUNTIME=1)
Static linking, requires rebuild to add modules (Emscripten apparently only supports asm.js dynamic linking when dynamic memory growth is disabled, which is not very useful)

Release Checklist

Update Changes.md with all changes since last release

As an example, to list changes since a specific version, excluding the regex tester:
```
$ git log --stat v0.05-beta.. -- . ':!web/regex_tester.html' ':!.gitignore'
```
- Also make sure that the documentation in using.md etc. mentions when features were added/deprecated

Update version numbers everywhere; use grep to find them, for example:

$ grep -Er --exclude-dir=hostperl --exclude-dir=.git --exclude-dir=emperl5 --exclude=emperl.* '0\.[01][0-9]' .
$ ( cd emperl5; grep -Er '0\.[01][0-9]' `git diff --numstat --diff-filter=ACMRT v5.28.1 HEAD | cut -f3` )

At a minimum there is:

web/webperl.js - Perl.WebPerlVersion
emperl5/ext/WebPerl/lib/WebPerl.pm - $VERSION
pages/index.md and pages/using.md - download links

Update Subresource Integrity values as needed, e.g.:

$ perl -wMstrict -MDigest::SRI=sri -le 'print sri "SHA-256","web/webperl.js"'

Build and create dist, e.g. build/build.pl --reconfig --dist=webperl_prebuilt_v0.07-beta
Test all build results, both from file://... and http://localhost
Add tags, the webperl repo gets an annotated tag such as v0.07-beta, and the emperl5 repo gets an unannotated tag such as webperl_v0.07-beta, then git push --tags
Create a release on GitHub and upload the webperl_prebuilt_*.zip as an asset
Uploading to AWS S3:
1. for X in emperl.* webperl.js; do gzip -v -9 $X && mv -v $X.gz $X ; done
2. Upload them with the appropriate Content-Type (see e.g. web/webperl.psgi) and a Content-Encoding of gzip
If there was a pages_for_vX.XX branch of gh-pages, don’t forget to merge that

Please see the “Legal” page for details.

You can find the source for this page at https://github.com/haukex/webperl/blob/gh-pages/notes.md

WebPerl

Misc. Notes on WebPerl

Links

Talks

“In the Press”

Prior Art

TODOs

SSL

Possible Improvements

Limitations

Release Checklist