One item that has been published in the Tuscany future roadmap
(http://tuscany.apache.org/sca-java-roadmap.html) is the need for Atom
binding etag and server sided caching support. JIRA TUSCANY-2447 has
been opened to track this feature.
I'd like to ask the Tuscany dev community for some of their ideas and
needs on this issue. Here are some of my ideas on this item.
Requirements
1) Provide a set of Tuscany APIs, helper classes, etc that enable
implementation of etag support and server side caching such as
last-modified on entries.
2) Support common caching protocols as defined in Atom Publishing
Protocol specification (see http://tools.ietf.org/html/rfc5023#section-9.5)
3) Implement HTTP header APIs and helper classes that enable conditional
caching support as given in the HTTP 1.1 specifications
(http://tools.ietf.org/html/rfc2616#section-13). Examples of these
request and response header fields are If-Match, If-None-Match, If-Range)
Here are some use cases that show how a server should respond to various
PUT and GET requests with provided etags:
1) Example HTTP PUT request (new entry put, new etag responded)
User client post request
POST /myblog/entries HTTP/1.1
Host: example.org
Content-Type: application/atom+xml;type=entry
Content-Length: nnn
Slug: First Post
<?xml version="1.0" ?>
<entry xmlns="http://www.w3.org/2005/Atom";>...</entry>
Atom server response (note unique ETag)
HTTP/1.1 201 Created
Date: Fri, 23 Feb 2007 21:17:11 GMT
Content-Length: nnn
Content-Type: application/atom+xml;type=entry
Location: http://example.org/edit/first-post.atom
Content-Location: http://example.org/edit/first-post.atom
ETag: "e180ee84f0671b1"
<?xml version="1.0" ?>
<entry xmlns="http://www.w3.org/2005/Atom";> ... </entry>
2) Conditional GET example (get with etag. entry is up to date)
User client GET request
GET /edit/first-post.atom HTTP/1.1
Host: example.org
If-None-Match: "e180ee84f0671b1"
Atom server response (item was up to date)
HTTP/1.1 304 Not Modified
Date: Sat, 24 Feb 2007 13:17:11 GMT
3) Conditional POST request (post with etag. entry provided is stale)
User client POST request
PUT /edit/first-post.atom HTTP/1.1
Host: example.org
Content-Type: application/atom+xml;type=entry
Content-Length: nnn
If-Match: "e180ee84f0671b1"
<?xml version="1.0" ?>
<entry xmlns="http://www.w3.org/2005/Atom";> ... </entry>
Atom server response (item was edited by another user)
HTTP/1.1 412 Precondition Failed
Date: Sat, 24 Feb 2007 16:34:11 GMT
I am by no means an expert on defining Tuscany requirements in this
area, so please correct me if I am off base. I would appreciate other
Tuscany users and developers views on what is needed.
--
Thanks, Dan Becker
