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https://issues.apache.org/jira/browse/MAPREDUCE-2399?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Luke Lu updated MAPREDUCE-2399:
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Description: Discuss the YARN web framework which is a part of
MAPREDUCE-279. (was: Discuss hamlet, UI framework which is a part of
MAPREDUCE-279.)
Summary: YARN web framework (was: Hamlet)
We needed a secure, lightweight *embedded* (in existing daemons) web framework
that can leverage all the security configurations in hadoop-commons HttpServer.
Most web frameworks assumes standalone webapps and want to dictate things like
directory layout and configurations etc. Major portion existing MVC frameworks
is devoted to some ORM layers that we don't need.
The main goals for the framework is security and ease of development (IDE
refactor friendly, esp. for typical Hadoop developers who're not professional
web developers with tons of plugins installed) and testing (webapps code needs
to be fully unit testable at controller and view level without booting up web
servers). This preclude frameworks that require embed class names in some
config files (properties or xml), which is arguably a pervasive java
anti-pattern.
It's very easy to accidentally write insecure and thread-unsafe code in
existing web frameworks. Anything that uses JSP as the view layer is insecure
and thread-unsafe by default (cf. HDFS-1758). In this framework, all views are
statically checked by the java compiler and every piece of data is escaped by
default. Thread-safety is simplified as controllers and views are request
scoped by default.
Hamlet is a novel and superior view technology that has no counter parts in any
existing framework/language in that it's IDE friendly (*without* having to
install tons of plugins): it gives instant autocompletion, javadoc and compiler
feedback, showing the current tag stack (see attached IDE screen-shots), making
it practically impossible to write invalid html (4.01 strict. In contrast, most
frameworks don't even generate valid html in their tutorials, neither do all
existing hadoop webapps.) The framework is precisely targeting devs who're not
html experts who don't know about quirks mode and remember html spec (e.g.,
block elements is forbidden inside inline elements etc.) by heart. In the end,
Hamlet is just a plain old java object builder (with creative use of generics)
that every Java developer can pickup without having to learn any new
(expression) language syntax that's needed for JSP(x) etc. (Spring MVC
typically use JSP as its view layer.)
Note, Hamlet.java only needs to be regenerated for people who want to hack on
the framework (fixing bugs or support new html5 tags etc.) Webapps just use
hamlet as a library. No xml, templates and config files to futz with. It just
works by default.
After wrote all the new webapps with it, I'm happy to report that the yarn web
framework achieved all the goals and then some. I have quite a few years
startup production experience with Rails and I honestly prefer this framework
despite it's in Java :), mostly due to Hamlet, Guice and the precise IDE
assisted refactor.
This framework might become a apache project by itself (like many other apache
projects come to be), as it's emerging as a perfect lightweight embedded web
framework for distributed systems. Note, this framework doesn't preclude a
standalone web app using a different framework more suitable for standalone
webapps, that pull data from different servers via (REST) APIs, in fact the
framework can serve web APIs in a very simple way (comparable or simpler then
typical JAX-RS implementations.)
See attachments for examples.
> YARN web framework
> ------------------
>
> Key: MAPREDUCE-2399
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2399
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Reporter: Arun C Murthy
> Assignee: Luke Lu
>
> Discuss the YARN web framework which is a part of MAPREDUCE-279.
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