Arno is spot on. The spec is being motherly, but in practice if you're
uploading assets, as opposed to saving something that must be considered part
of a transaction, then there's no harm done in writing to the file system.
Everybody does it! Here's an example:
http://jumpstart.doublenegative.com.au/jumpstart/examples/javascript/fileupload
If you're in a clustered environment then just make sure the file is written to
a file location that is shared across the cluster.
If the saved files are then to be served up in high volume (eg. lots of images
on a page to lots of users) then it may be preferable to return special URLs
for them rather than have Tapestry's return them as asset addresses. The
special URLs could be detected by Apache (in front of Tapestry) which can then
serve them up directly from the file system (rather than have Tapestry stream
them).
Of course if there are security requirements (ie. who is allowed to see what
files) or the need for a CDN then more is required than I've suggested above.
Geoff
On 25/05/2012, at 6:59 PM, Chris Mylonas wrote:
> 626 pages of spec... and you reply with section number and some copy and
> paste.
> I am grateful Arno, thank you!
>
>
> On 25/05/2012, at 5:45 PM, Arno Haase wrote:
>
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>> JEE application servers typically do not actually prevent you from
>> accessing the file system, and the spec does not require them to. So
>> if it works with your specific app server / jee stack, you are home free.
>>
>> The spec prohibits accessing the file system sort of to protect you
>> from yourseslf - the file system is not transactional, needs attention
>> in a clustered environment etc.
>>
>> That is specified in section 21.2.2 "Programming Restrictions" of the
>> EJB 3.1 specification (JSR 318,
>> http://www.oracle.com/technetwork/java/javaee/tech/index.html):
>>
>>
>> •An enterprise bean must not use the java.io package to attempt to
>> access files and directories in the file system.
>>
>> The file system APIs are not well-suited for business components to
>> access data. Business components should use a resource manager API,
>> such as JDBC, to store data.
>>
>>
>> The bottom line is:
>> * the spec allows file system access from a servlet. The restriction
>> applies only to EJBs.
>> * Even from EJBs it works and is likely to continue working.
>> * But accessing the file system from an EJB formally makes an
>> application not strictly JEE6 compliant.
>>
>> I hope that helps
>>
>> - - Arno
>>
>>
>> Am 25.05.2012 03:23, schrieb Chris Mylonas:
>>> Hi Tapestry Users,
>>>
>>> In April there was a thread about AssetFactory help [1] and it
>>> mentioned that the J2EE spec states that you should not read or
>>> write to the file system. Reading up on the collapsed ear from
>>> openejb's website [2] they say (sic) "not quite j2ee but truly
>>> jee6".
>>>
>>> Although openejb is referencing class loading, where would I find
>>> info about whether jee6 allows reading/writing to local
>>> filesystem? It's a handy bad habit I'd like to be able to access -
>>> I know it's something I was doing back in early 2000s with tomcat 5
>>> unknowingly being a badass.
>>>
>>> Any help would be greatly appreciated, Chris
>>>
>>>
>>>
>>> [1] =
>>> http://tapestry.1045711.n5.nabble.com/File-System-Asset-Factory-help-needed-and-petition-wanted-td5641308.html
>>>
>>>
>> [2] = https://openejb.apache.org/collapsed-ear.html
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