RE: [Xen-API] XenAPI, xapi toolstack, XendAPI, XL

[Dave Scott <Dave.Scott@xxxxxxxxxxxxx>]

Hi George,

It is a bit confusing. Here's the history:

* In the beginning was "xend" (the daemon) and "xm" (the CLI) both written in 
python, which communicated over an s-expression protocol.
* Next there was a desire to improve the protocol and also to switch from 
s-expressions to something based on XMLRPC. The "XenAPI" is the name for this 
new protocol.
* The "XenAPI" was implemented both in "xend" (python) and in "xapi" (ocaml) 
(although "xapi" wasn't open-source back then). Note that "xapi" doesn't share 
any code with "xend": it talks to xenstore, makes hypercalls etc directly.
* The version of the "XenAPI" implemented by "xend" and "xapi" have diverged: 
for example "xapi" is more focused on managing pools of hosts while "xend" is 
more of a single host service.
* The XCI (Xen Client Initiative) people also created a toolstack, called 
"xenvm" (ocaml)
* Next there was a desire to share more code between all toolstacks, to prevent 
confusion and accidental reimplementation. The library with the common code is 
called "libxl"
* Next there was a desire to create a "minimal" toolstack for testing "libxl": 
this is called "xl"

So:

Toolstacks: xend (python); xapi (ocaml); xenvm (ocaml); xl (C)
Protocols: original xend s-expressions; XenAPI (XMLRPC)
Libraries: libxl


Cheers,
Dave

> -----Original Message-----
> From: xen-api-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-api-
> bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of George Shuklin
> Sent: 16 August 2010 16:22
> To: xen-api@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-API] XenAPI, xapi toolstack, XendAPI, XL
> 
> I feel myself little lost. I'm trying to figure relationship between
> components of xen (it tools). Please, correct me if I wrong.
> 
> XenAPI: XML-PRC via HTTP between xm and xend. Provided by xend, can be
> used by anyone. Xend wroted in Python, used in standalone xen
> installation (within Debian, RHEL, etc).
> 
> XAPI toolstack - some kind of wraper for XenAPI, wroted in OCaml, used
> in XCP.
> 
> And here questions: is XAPI and XenAPI same thing? (And what is
> XendAPI?). If XAPI toolstack and XenAPI same thing, does OCaml code
> reimplement XenAPI? Or reuse xend code?
> 
> 
> I hear about some other library to interact with xen: XL (libxl). But I
> could not find any documentation outside source code in xen-unstable.hg.
> 
> Please, help.
> 
> 
> 
> 
> 
> 
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