It's being worked on at https://github.com/joyent/node/wiki/API-changes-between-v0.10-and-v0.12
On Mon, Jul 8, 2013 at 12:02 PM, Dean Mao <dean...@gmail.com> wrote: > Is there a summary of ABI changes for us native module authors? > > > On Mon, Jul 8, 2013 at 2:53 PM, Stephen Belanger <cyruzdr...@gmail.com>wrote: > >> I feel like this is a good chance to just throw out backwards >> compatibility and start fresh. There are many decisions that were made in >> both C++ and Javascript sides that could have been done better, in >> retrospect. They stuck though because no one wanted to break compatibility >> with old versions of node. A good example is the recent changes to streams >> which, while they are an improvement, are basically a bad hack to twist a >> better API to sorta-kinda work with the bad API. >> >> On Monday, 8 July, 2013 at 11:35 AM, Timothy J Fontaine wrote: >> >> [cross post from http://atxconsulting.com/2013/07/06/rewrite-it-anyway/] >> >> Node v1.0 is approaching, and v0.12 is imminent (as far as that goes for >> FOSS >> projects). As we work towards getting v0.12 out the door, there have been >> a lot >> of changes happening for node's primary dependency v8. Ben is working on >> moving >> us to the 3.20 branch, follow his progress >> [here](https://github.com/joyent/node/pull/5804). >> >> As you can tell this is a signficant change to the API, which requires a >> touch >> of virtually every file in our `src/`, this has been a huge headache for >> him, >> and will ultimately cause a huge headache for developers of binary addons. >> >> You're going to have to `#ifdef` around significant portions of the API >> to keep >> your module working across different version of node, this is going to >> cause >> endless amounts of pain and issues for node and developers who have for >> the >> most part been accepting of the churn in our underspecified addon API. >> >> This one is going to hurt. >> >> A lot. >> >> ## TL;DR -- A modest proposal >> >> Since you're going to have to rewrite your module anyway, it's time for >> node to >> specify and export the API we are going to "bless" for addons. That is, >> just >> what API we are going to support and make sure continues to work from >> minor and >> major releases, as well as a deprecation policy. >> >> More specifically I think we should be exporting a separate (and not >> equal) >> wrapper around (at the very least) javascript object creation, get/set, >> function >> calling. >> >> Additionally we should package and distribute (if possible in npm) a >> transitional library/headers which module authors can target today which >> will >> allow their module to compile and work from v0.8 through v1.0 >> >> ## The Platform Problem >> >> We currently allow platforms/distributors to build against shared (their >> own) >> versions of many of our dependencies, including but not limited to: >> >> * v8 >> - Holy crap, we're about as tightly coupled to the version of v8 we >> ship as >> chromium itself is. >> * libuv >> - If we weren't strictly coupled to v8, we certainly are for libuv, >> there >> would be no (useful) node, without libuv. >> * openssl >> - This is a must for linux distributions, who like to break DSA keys >> and then >> make every dependency vulnerable as a result (sorry Debian, I keed I >> keed). >> - This actually allows distributors who know specific things about >> their >> platform to enable/disable the features that allow it to run best. >> * zlib >> - Meh, this isn't such a big deal, it doesn't really change all that >> often. >> * http_parser >> - Really? People ship this as a separate library? >> >> This functionality was added to appease platform builders, the likes of >> Debian, >> Fedora, and even SmartOS. However, doing so has complicated and muddled >> the >> scenario of building and linking binary addons. >> >> Currently node-gyp downloads the sourceball, extracts the headers from it, >> and makes some assumptions from `process.config` about how to build your >> addon. >> In practice this has been working reasonably well. >> >> However, I'm very concerned about this as a long term strategy. It's >> possible >> for someone to have tweaked or twisted the node (or one of its >> dependencies) >> builds, which could lead to some unintended consequences. In the "best" >> case, >> you'll get a compiler error from a changed API or clashing symbol. In the >> worst >> case they have modified the ABI which will manifest itself in unexpected >> and >> often subtle ways. >> >> Not to mention that we have no good answer on how to build and link addon >> modules against the proper version of a shared dependency (what if the >> system >> has multiple openssl's, what if they compiled against it in one place, >> but now >> run against it in another). >> >> And last but not least, how do modules consume symbols from our >> dependencies >> that node itself doesn't consume. Consider a specific crypto routine from >> openssl that you want to provide as an addon module because node doesn't >> currently have an interface for it. >> >> ## Enemies without, and enemies within >> >> As if it weren't bad enough that platforms may ship against a version of >> v8 >> that we haven't blessed, we (and addon developers) have to fight against >> the >> beast that is the v8 API churn. >> >> I don't really fault Google and the chromium or v8 team for how they are >> handling this, more often then not we just end up with ugly compile time >> deprecation warnings, letting us know the world is about to break. >> >> However, there have been times -- like right now -- where node can't >> paper over >> the drastic change in the v8 API for module developers. And as a result we >> begrudgingly pass the API change to module authors. >> >> To paraphrase, don't forget that execrement will inevitably lose its >> battle >> with gravity. >> >> So what are we going to do? >> >> ## Meat and Potatoes >> >> This is where I don't particularly have everything fleshed out, and I'm >> sure I >> will take a considerable amount of heat from people on API decisions that >> haven't been made. >> >> I want to export the following interfaces: >> >> * `node/js.h` >> - Object creation and manipulation. >> - Function calling and Error throwing. >> * `node/platform.h` >> - IO and event loop abstraction. >> * `node/ssl.h` >> * `node/zlib.h` >> * `node/http.h` >> >> While I am not particularly attached to the names of these headers, each >> represent an interface that I think module authors would opt to target. I >> only >> feel strongly that we export `js` and `platform` as soon as possible as >> they are the primary interactions for every module. >> >> ### Basic Principles >> >> There are only a few principles: >> >> * Avoid (like the plague) any scenario where we expose an ABI to module >> authors. >> - Where possible use opaque handles and getter/setter functions. >> * The exported API should be a reliable interface which authors can >> depend on >> working across releases. >> * While a dependency may change its API, we have committed to our >> external API >> and need to provide a transitional interface in accordance with our >> deprecation >> policy. >> * The API should never expose an implementation detail to module authors >> (A >> spidermonkey backed node one day?). >> >> ### Platform >> >> The `platform` interface is the easiest to discuss, but the pattern would >> follow for `ssl`, `zlib`, and `http`. >> >> This would just rexport the existing `uv` API, however with a C-style >> namespace >> of `node_`. Any struct passing should be avoided, and libuv would need to >> be >> updated to reflect that. >> >> ### JS >> >> I expect the `js` interface to be the most contentious, and also fraught >> with >> peril. >> >> The interface for addon authors should be C, I don't want to forsake the >> C++ >> folk, but I think the binding for that should be based on our C interface. >> >> I was going to describe my ideal interface, and frame it in context of my >> ruby >> and python experience. However, after a brief investigation, the JSAPI for >> spidermonkey exports almost exactly the API I had in mind. So read about >> that >> [here]( >> https://developer.mozilla.org/en-US/docs/SpiderMonkey/JSAPI_User_Guide). >> >> Would it make sense, and would it be worth the effort, for node to export >> a >> JSAPI compatible interface? >> >> Would it make more sense to export a JSAPI influenced API currently >> targetted >> at v8 which could be trivially extended to also support spidermonkey? >> >> UPDATE 2013-07-08: >> >> > It's interesting and worthy to have a conversation about being able to >> > provide a backend neutral object model, though our current coupling to >> v8 and >> > its usage in existing addons may not make it possible to entirely hide >> away >> > the eccentricities of the v8 API. But what we can provide is an >> interface >> > that is viable to target against from release to release regardless of >> how >> > the public v8 API changes. >> >> ## Prior Art >> >> A lot of these ideas came from a discussion I had with >> [Joshua Clulow](http://blog.sysmgr.org/) while en route to >> [NodeConf](http://nodeconf.com). >> >> Part of that conversation was about [v8+]( >> https://github.com/wesolows/v8plus) >> which was written by a particularly talented coworker, who had a rather >> nasty >> experience writing for the existing C++ API (such as it is). >> >> There's some overlap in how it works and how I envisioned the new API. >> However, >> I'm not sure I'm particularly fond of automatically converting objects >> into >> nvlists, though that does solve some of the release and retain issues. >> >> In general I would advocate opaque handles and getter and setter >> functions, >> with a helper API which could do that wholesale conversion for you. >> >> Really though this matters less in a world where addon authors are >> following >> some defined "Best Practices". >> >> * Only pass and return "primitives" to/from the javascript/C boundary >> - Primitives would be things like: `String`, `Number`, `Buffer`. >> * Only perform objection manipulation in javascript where the JIT can >> work >> its magic >> >> ## Dessert >> >> Work on this needs to begin as soon as possible. We should be able to >> distribute it in npm, and authors should be able to target it by >> including a >> few headers in their source and adding a dependency stanza in their >> `binding.gyp`, and by doing so their module will work from v0.8 through >> v1.0 >> >> I mean, you're going to have to rewrite it anyway. >> >> -- >> -- >> Job Board: http://jobs.nodejs.org/ >> Posting guidelines: >> https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines >> You received this message because you are subscribed to the Google >> Groups "nodejs" group. >> To post to this group, send email to nodejs@googlegroups.com >> To unsubscribe from this group, send email to >> nodejs+unsubscr...@googlegroups.com >> For more options, visit this group at >> http://groups.google.com/group/nodejs?hl=en?hl=en >> >> --- >> You received this message because you are subscribed to the Google Groups >> "nodejs" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to nodejs+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> >> >> -- >> -- >> Job Board: http://jobs.nodejs.org/ >> Posting guidelines: >> https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines >> You received this message because you are subscribed to the Google >> Groups "nodejs" group. >> To post to this group, send email to nodejs@googlegroups.com >> To unsubscribe from this group, send email to >> nodejs+unsubscr...@googlegroups.com >> For more options, visit this group at >> http://groups.google.com/group/nodejs?hl=en?hl=en >> >> --- >> You received this message because you are subscribed to the Google Groups >> "nodejs" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to nodejs+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > > -- -- Job Board: http://jobs.nodejs.org/ Posting guidelines: https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines You received this message because you are subscribed to the Google Groups "nodejs" group. 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