[opencms-dev] Challange! External Program access to OpenCMS Instance...

[M Butcher]

All right... I'll give a longer answer:

1) For one servlet/app to be able to access the runtime vars of another 
servlet/app would be a big security risk. However, somewhere in the 
Tomcat docs, there may be info on doing that. You could look for that. 
I'd be surprised if it was allowed, though.

2) I've seen an app that worked directly on the OpenCMS database. It 
could directly manipulate the data that OpenCMS could access -- HOWEVER, 
it broke just about every safety constraint that OpenCMS put in place 
(for instance, locking). While it's possible, I'd only implement this if 
the external process was only reading the DB (not writing), so that is 
probably out for you.

3) You could try to find a way to externally get an interface to an 
OpenCms object. Alexander may know of a way, but it is certainly not 
documented, nor obvious from the code. In fact, I can't think of a way 
that this would even be done. The CmsShell does something like this (I 
think it creates a new instance of whatever class implements A_OpenCms), 
but IIRC there were some warnings about running it while the servlet was 
running (since you have two instances of A_OpenCms).

4) You can implement some sort of RPC mechanism, such as SOAP. I 
wouldn't imagine that it would really be a bottleneck, but it would 
certainly take a long time to develop. When you think about it, net 
sockets are just another form of IPC, and when the language is (like 
Java) considerably abstracted from the underlying OS, sockets are one of 
the few viable IPC mechanisms. You can, of course, look into the other 
Java ORB-style stuff as well, though I can't imagine that being faster 
to implement.

5) You can screen-scrape. I generally consider this a bad idea. You 
would basically write a web client to work over HTTP with HTML.

6) Depending on your circumstances, you may be able to do some sort of 
pseudo-IPC by setting up a cron class to check a queue (either in the FS 
or in a new DB table(s)) for new information, and then process whatever 
you need. Then the other application would only have to drop info into 
the queue. Or you may set up that cron class to simply start the other 
program (in code) and manipulate the data.

Matt

Ralf Bierig wrote:

>Hi,
>
>thank you for your suggestion. But if I want to stay on the same machine and
>it would be not very beneficial to introduce such an extreme bottleneck like
>SOAP. An API call would prob. be a 100 times faster...
>
>Is there no direct method?
>
>Cheers,
>Ralf
>
>  
>
>>Implement SOAP or XML-RPC commands and use HTTP(S) for transport?
>>
>>Matt
>>
>>ambiesense at gmx.de wrote:
>>
>>    
>>
>>>Hi,
>>>
>>>some time ago I posted the question about the possibility to perform the
>>>following szenario, which I think is quite a challange:
>>>
>>>On the Server Tomcat is running with OpenCMS 5.0 inside. Also on the
>>>      
>>>
>>server,
>>    
>>
>>>there is a Java program which accesses this OpenCMS instance through the
>>>Tomcat servlet engine (or otherwise). The program should be able to
>>>      
>>>
>>access all
>>    
>>
>>>runtime (instance) information like user/usergroup info as well as static
>>>      
>>>
>>info
>>    
>>
>>>like files etc. The program would log in, access files (read/write) do
>>>administration etc. and log out after finishing its tasks. There could be
>>>      
>>>
>>more
>>    
>>
>>>then one program to access the same instance and work similaniously.
>>>      
>>>
>>These
>>    
>>
>>>programms would work like users simulaniously.
>>>
>>>How could this be archived?? 
>>>
>>>The only, not tested, possiblity offered at that time was using an
>>>      
>>>
>>apporach
>>    
>>
>>>similar to what the CMSShell is doing. However this approach does not
>>>      
>>>
>>work
>>    
>>
>>>really like a client since it builts a server with all the database
>>>      
>>>
>>connection
>>    
>>
>>>and other ballast. I basically want just an access point to the instance
>>>though the API. This means basically an access the CMSObject by using
>>>      
>>>
>>normal API
>>    
>>
>>>interface (and not via JSP).
>>>
>>>Does somebody has any ideas of how this could be done? Does OpenCMS offer
>>>      
>>>
>>a
>>    
>>
>>>way of doing that?
>>>
>>>Any help would be hightly appreciated,
>>>Ralf  
>>>
>>> 
>>>
>>>      
>>>
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>>    
>>
>
>  
>