Hello André,
Thank you for your detailed answer, your accurate terminology and the
links you sent me.
About the scenario I described in my first message: I could make it work.
> [André Warnier wrote:]
> And note that when one of your servlets issues a HTTP request to
another server, Tomcat knows absolutely nothing about it, and there is
no Tomcat code involved (on the request-sending side).
Ah? Ok.
"What" is actually taking care of the HTTP request then?
> [André Warnier wrote:]
> [...] for creating and sending a HTTP POST request [...]
> [...] to create a stand-alone java network server, which just listens
for this particular kind of request, and responds by the information
that you describe [...]
I actually have another scenario in which a C++ executable has to send a
HTTP request to a Tomcat Webapp.
I would need to build the HTTP request inside the C++ code and then send
it to the Tomcat Webapp.
I haven't yet looked for a solution...
Again thank you and best regards.
--
Léa
On 2014-06-16 5:51 PM, André Warnier wrote:
Lmhelp1 wrote:
Hello,
My question is about what code to write to allow two remote Tomcat
webapps to communicate with one another through the Internet.
Let me explain more precisely what I would like to do.
(I'm just simplifying a bit the real situation).
- I have a Tomcat webapp running on a server in England.
- I have another Tomcat webapp running on a server in France.
- I have a JSP inside the England webapp.
- This JSP contains a form with two fields "First name" and "Last name".
- I would like to send these information to the France webapp.
- After the England form has been submitted, I can collect the
information "First name" and "Last name" in a servlet.
Can you tell me what I shall do then to send these information to the
France webapp?
Is it something like a "response.sendRedirect(..."?
How does it have to be written?
- Meantime, the France webapp needs to be able to wait for these
information and, when they arrive, to get them and do something with
them. For example store the "First name" and "Last name" in a
database, etc.
What kind of a code has to be written in the France webapp?
Is it a servlet with a "doGet()" retrieving the information "First
name" and "Last name"?
- Moreover, when the France webapp has finished it's job, it needs to
tell the England webapp that it has finished, send it a file and some
information.
So the communication has to be bidirectional.
Can you please give me some indications on how to start dealing with
this? Or maybe a tutorial or an example?
This is only vaguely a Tomcat question, in the sense that :
- for receiving and processing a HTTP POST request (from a browser
usually, but in your case it would be a Tomcat servlet or a program
running somewhere else), a normal webapp is what you need.
- for creating and sending a HTTP POST request, you will need a library
that offers such functions, such as the HTTPClient library, found here :
http://projects.apache.org/projects/httpcomponents_client.html
There is documentation and examples available at :
http://hc.apache.org/index.html.
Make sure you read them.
Note that any java program could use this, there is nothing special
about using it within a java servlet.
And note that when one of your servlets issues a HTTP request to another
server, Tomcat knows absolutely nothing about it, and there is no Tomcat
code involved (on the request-sending side).
Note also that for what you describe as the "France webapp" above, that
functionality does not necessarily need a Tomcat and a Tomcat webapp.
You could use the code of
http://projects.apache.org/projects/httpcomponents_core.html
to create a stand-alone java network server, which just listens for this
particular kind of request, and responds by the information that you
describe.
Similarly, your "England webapp" does not necessarily need to send the
request to the France server as a HTTP request, nor expect a HTTP response.
What I believe would be the trickiest part in that kind of application,
is to handle the various error scenarios : network down between England
and France, French server down, French server taking a (too) long time
to respond, French server returning an error, etc..
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