Re: Initiating httpservletrequest from inside Tomcat / TomEE
On 5/6/2019 10:45 AM, Paul Carter-Brown wrote:
Yea, but the issue is that only works when calling in the context of a
current servlet call.
Here is the kind of problem I want to solve:
@WebServlet(name = "MyExample", urlPatterns = {"/example"}, loadOnStartup =
1)
public class Example extends HttpServlet {
@PersistenceContext
private EntityManager em;
@Override
public void init(ServletConfig config) {
Thread t = new Thread(() -> {
while (true) {
try {
// Do a GET to /example/ and get the response without
going out on localhost and back in
// We cant just call doGet as we want the request to
flow through the servlet filters, do the entitymanager injection etc
Thread.sleep(1);
} catch (Exception e) {
}
}
});
t.start();
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// do stuff like use em
resp.setStatus(200);
resp.getWriter().write("Hello World");
}
}
If I understand the problem you're trying to solve, it seems like there
could be two ways to approach it.
1) Can your service be initialized with the context information it needs
to use the request dispatcher?
2) Can the servlets you want to use be refactored so that the underlying
functionality is exposed in a way that doesn't require any context?
Hope that helps.
-Terence
On Mon, May 6, 2019 at 5:35 PM John Dale wrote:
For reference, I did find this after searching "calling a servlet
programmatically":
https://docs.oracle.com/cd/E19146-01/819-2634/abxbn/index.html
On 5/6/19, Paul Carter-Brown wrote:
I think we are completely missing each other. Forget sockets - that was
just an example. I have code running in a Tomcat App server which is not
managed by Tomcat and is not initiated by anything within Tomcat. That
code
now wants to call a servlet hosted in that very same JVM. Any way to do
that without going out and back in on TCP?
On Mon, May 6, 2019 at 5:14 PM John Dale wrote:
Sockets are an implementation of TCP/UDP inherently.
Perhaps a mountaintop signal fire?
;)
John
On 5/6/19, Paul Carter-Brown wrote:
lol on the Semaphore Telegraph,
I can't use a request dispatcher as the request is being initiated
from
code that has no context. I already have it working with HTTP using
asynchttp library, but I want to avoid the overhead. E.g. lets say I
wrote
my own server socket listener on port 1 running in the Tomcat JVM
and
got some request in some propriatary protocol called X. Now I want to
call
a Tomcat servlet in the current JVM with some info I got over X
without
going out on TCP and back in
On Mon, May 6, 2019 at 4:40 PM John Dale wrote:
If you're wanting to forward control to another servlet deployed in
the same context:
https://www.javatpoint.com/requestdispatcher-in-servlet
If you are okay going through TCP to facilitate some future or
current
distribution of services, Use HTTPURLConnection (not sure what you're
wanting to do with the result of the request, if anything):
https://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests
If you need more sophisticated HTTP interactions, Apache maintains a
very useful library for that: http://hc.apache.org/
If these don't work-out for you, rather than using .NET, PHP, Python,
or some other Java facsimile at best, I recommend using the semaphore
telegraph:
https://en.wikipedia.org/wiki/Semaphore_telegraph
Sincerely,
John
DB2DOM
On 5/6/19, Paul Carter-Brown wrote:
Hi John,
Thanks for your feedback.
The request I'm initiating should not or need not carry any context
from
the originating code. There is also no session to worry about as
its
just
for rest calls. So basically I have the headers, path and body and
need
to
generate a http servlet request and get an http servlet response
(or
similar) back. I have this working by calling into localhost but
ideally
want to skip the trombone out and back in.
Have you got any basic code examples?
Paul
On Tue, Apr 30, 2019 at 5:27 PM John Dale
wrote:
Another thought .. you can do some request dispatching, but
without
knowing more about the tools you're using, I can't say for sure if
this is the direction you'll want to go.
On 4/29/19, Paul Carter-Brown
wrote:
Hi
I'm trying to design a Kafka consumer and producer that will run
inside
the
tomcat jvm and pick up messages off a Kafka topic and translate
them
into a
servlet request and pass it through tomcat and then when the
response
is
complete then translate it into a Kafka message and put it onto
another
topic as a reply. This way I can reuse our existing jax-rs rest
services
and expose them as an async api over Kafka. The idea is to make
the
Kafka
messages simila
Re: Initiating httpservletrequest from inside Tomcat / TomEE
I didn't think that TomEE was Tomcat. Wasn't it it's own thing??? I mean
TomEE is this separate project maintained by this up here in Seattle vs
Tomcat which is an Apache Project.
Owen Rubel
oru...@gmail.com
On Mon, May 6, 2019 at 9:16 AM Paul Carter-Brown
wrote:
> Hi John,
>
> See original request. It's pretty much a Kafka/Servlet proxy/gateway:
>
> I'm trying to design a Kafka consumer and producer that will run inside the
> tomcat jvm and pick up messages off a Kafka topic and translate them into a
> servlet request and pass it through tomcat and then when the response is
> complete then translate it into a Kafka message and put it onto another
> topic as a reply. This way I can reuse our existing jax-rs rest services
> and expose them as an async api over Kafka. The idea is to make the Kafka
> messages similar to http in that they would consist of headers and a body.
> The body would be json.
>
>
> On Mon, May 6, 2019 at 6:13 PM John Dale wrote:
>
> > You could try debugging the tomcat code and find out how, right after
> > it parses the TCP request, it invokes the servlet. You can then
> > create your own harness for tomcat code after initializing the
> > appropriate context for the request to tomcat. I don't know off hand
> > where in the tomcat code this cut point can be found.
> >
> > Is this a performance issue, or are you building a proxy?
> >
> > What is the problem you're trying to solve?
> >
> > On 5/6/19, Paul Carter-Brown wrote:
> > > Yea, but the issue is that only works when calling in the context of a
> > > current servlet call.
> > >
> > > Here is the kind of problem I want to solve:
> > >
> > > @WebServlet(name = "MyExample", urlPatterns = {"/example"},
> > loadOnStartup =
> > > 1)
> > > public class Example extends HttpServlet {
> > >
> > > @PersistenceContext
> > > private EntityManager em;
> > >
> > > @Override
> > > public void init(ServletConfig config) {
> > > Thread t = new Thread(() -> {
> > > while (true) {
> > > try {
> > > // Do a GET to /example/ and get the response
> without
> > > going out on localhost and back in
> > > // We cant just call doGet as we want the request
> to
> > > flow through the servlet filters, do the entitymanager injection etc
> > > Thread.sleep(1);
> > > } catch (Exception e) {
> > > }
> > > }
> > > });
> > > t.start();
> > >
> > > }
> > >
> > > @Override
> > > protected void doGet(HttpServletRequest req, HttpServletResponse
> > resp)
> > > throws ServletException, IOException {
> > > // do stuff like use em
> > > resp.setStatus(200);
> > > resp.getWriter().write("Hello World");
> > > }
> > >
> > > }
> > >
> > >
> > >
> > >
> > > On Mon, May 6, 2019 at 5:35 PM John Dale wrote:
> > >
> > >> For reference, I did find this after searching "calling a servlet
> > >> programmatically":
> > >> https://docs.oracle.com/cd/E19146-01/819-2634/abxbn/index.html
> > >>
> > >> On 5/6/19, Paul Carter-Brown wrote:
> > >> > I think we are completely missing each other. Forget sockets - that
> > was
> > >> > just an example. I have code running in a Tomcat App server which is
> > >> > not
> > >> > managed by Tomcat and is not initiated by anything within Tomcat.
> That
> > >> code
> > >> > now wants to call a servlet hosted in that very same JVM. Any way to
> > do
> > >> > that without going out and back in on TCP?
> > >> >
> > >> >
> > >> > On Mon, May 6, 2019 at 5:14 PM John Dale wrote:
> > >> >
> > >> >> Sockets are an implementation of TCP/UDP inherently.
> > >> >>
> > >> >> Perhaps a mountaintop signal fire?
> > >> >>
> > >> >> ;)
> > >> >>
> > >> >> John
> > >> >>
> > >> >>
> > >> >> On 5/6/19, Paul Carter-Brown wrote:
> > >> >> > lol on the Semaphore Telegraph,
> > >> >> >
> > >> >> > I can't use a request dispatcher as the request is being
> initiated
> > >> from
> > >> >> > code that has no context. I already have it working with HTTP
> using
> > >> >> > asynchttp library, but I want to avoid the overhead. E.g. lets
> say
> > I
> > >> >> wrote
> > >> >> > my own server socket listener on port 1 running in the Tomcat
> > >> >> > JVM
> > >> >> > and
> > >> >> > got some request in some propriatary protocol called X. Now I
> want
> > >> >> > to
> > >> >> call
> > >> >> > a Tomcat servlet in the current JVM with some info I got over X
> > >> without
> > >> >> > going out on TCP and back in
> > >> >> >
> > >> >> > On Mon, May 6, 2019 at 4:40 PM John Dale
> > wrote:
> > >> >> >
> > >> >> >> If you're wanting to forward control to another servlet deployed
> > in
> > >> >> >> the same context:
> > >> >> >> https://www.javatpoint.com/requestdispatcher-in-servlet
> > >> >> >>
> > >> >> >> If you are okay going through TCP to facilitate some future or
> > >> current
> > >> >> >> distribution of services, Use HTTPURLConnection (not su
Re: Initiating httpservletrequest from inside Tomcat / TomEE
I would trace tomcat and recreate a servlet request .. see if I could
hack it in that way (assuming that localhost traffic isn't fast
enough). Normalizing on HTTP/TCP will be more maintainable, though?
Can somebody suggest a good place for a breakpoint?
Any other suggestions?
John
On 5/6/19, Paul Carter-Brown wrote:
> Hi John,
>
> See original request. It's pretty much a Kafka/Servlet proxy/gateway:
>
> I'm trying to design a Kafka consumer and producer that will run inside the
> tomcat jvm and pick up messages off a Kafka topic and translate them into a
> servlet request and pass it through tomcat and then when the response is
> complete then translate it into a Kafka message and put it onto another
> topic as a reply. This way I can reuse our existing jax-rs rest services
> and expose them as an async api over Kafka. The idea is to make the Kafka
> messages similar to http in that they would consist of headers and a body.
> The body would be json.
>
>
> On Mon, May 6, 2019 at 6:13 PM John Dale wrote:
>
>> You could try debugging the tomcat code and find out how, right after
>> it parses the TCP request, it invokes the servlet. You can then
>> create your own harness for tomcat code after initializing the
>> appropriate context for the request to tomcat. I don't know off hand
>> where in the tomcat code this cut point can be found.
>>
>> Is this a performance issue, or are you building a proxy?
>>
>> What is the problem you're trying to solve?
>>
>> On 5/6/19, Paul Carter-Brown wrote:
>> > Yea, but the issue is that only works when calling in the context of a
>> > current servlet call.
>> >
>> > Here is the kind of problem I want to solve:
>> >
>> > @WebServlet(name = "MyExample", urlPatterns = {"/example"},
>> loadOnStartup =
>> > 1)
>> > public class Example extends HttpServlet {
>> >
>> > @PersistenceContext
>> > private EntityManager em;
>> >
>> > @Override
>> > public void init(ServletConfig config) {
>> > Thread t = new Thread(() -> {
>> > while (true) {
>> > try {
>> > // Do a GET to /example/ and get the response
>> > without
>> > going out on localhost and back in
>> > // We cant just call doGet as we want the request
>> > to
>> > flow through the servlet filters, do the entitymanager injection etc
>> > Thread.sleep(1);
>> > } catch (Exception e) {
>> > }
>> > }
>> > });
>> > t.start();
>> >
>> > }
>> >
>> > @Override
>> > protected void doGet(HttpServletRequest req, HttpServletResponse
>> resp)
>> > throws ServletException, IOException {
>> > // do stuff like use em
>> > resp.setStatus(200);
>> > resp.getWriter().write("Hello World");
>> > }
>> >
>> > }
>> >
>> >
>> >
>> >
>> > On Mon, May 6, 2019 at 5:35 PM John Dale wrote:
>> >
>> >> For reference, I did find this after searching "calling a servlet
>> >> programmatically":
>> >> https://docs.oracle.com/cd/E19146-01/819-2634/abxbn/index.html
>> >>
>> >> On 5/6/19, Paul Carter-Brown wrote:
>> >> > I think we are completely missing each other. Forget sockets - that
>> was
>> >> > just an example. I have code running in a Tomcat App server which is
>> >> > not
>> >> > managed by Tomcat and is not initiated by anything within Tomcat.
>> >> > That
>> >> code
>> >> > now wants to call a servlet hosted in that very same JVM. Any way to
>> do
>> >> > that without going out and back in on TCP?
>> >> >
>> >> >
>> >> > On Mon, May 6, 2019 at 5:14 PM John Dale wrote:
>> >> >
>> >> >> Sockets are an implementation of TCP/UDP inherently.
>> >> >>
>> >> >> Perhaps a mountaintop signal fire?
>> >> >>
>> >> >> ;)
>> >> >>
>> >> >> John
>> >> >>
>> >> >>
>> >> >> On 5/6/19, Paul Carter-Brown wrote:
>> >> >> > lol on the Semaphore Telegraph,
>> >> >> >
>> >> >> > I can't use a request dispatcher as the request is being
>> >> >> > initiated
>> >> from
>> >> >> > code that has no context. I already have it working with HTTP
>> >> >> > using
>> >> >> > asynchttp library, but I want to avoid the overhead. E.g. lets
>> >> >> > say
>> I
>> >> >> wrote
>> >> >> > my own server socket listener on port 1 running in the Tomcat
>> >> >> > JVM
>> >> >> > and
>> >> >> > got some request in some propriatary protocol called X. Now I
>> >> >> > want
>> >> >> > to
>> >> >> call
>> >> >> > a Tomcat servlet in the current JVM with some info I got over X
>> >> without
>> >> >> > going out on TCP and back in
>> >> >> >
>> >> >> > On Mon, May 6, 2019 at 4:40 PM John Dale
>> wrote:
>> >> >> >
>> >> >> >> If you're wanting to forward control to another servlet deployed
>> in
>> >> >> >> the same context:
>> >> >> >> https://www.javatpoint.com/requestdispatcher-in-servlet
>> >> >> >>
>> >> >> >> If you are okay going through TCP to facilitate some future or
>> >> current
>> >> >> >> distribution of services, Use HTTPURLConnection (not sure what
>>
Re: Initiating httpservletrequest from inside Tomcat / TomEE
Hi John,
See original request. It's pretty much a Kafka/Servlet proxy/gateway:
I'm trying to design a Kafka consumer and producer that will run inside the
tomcat jvm and pick up messages off a Kafka topic and translate them into a
servlet request and pass it through tomcat and then when the response is
complete then translate it into a Kafka message and put it onto another
topic as a reply. This way I can reuse our existing jax-rs rest services
and expose them as an async api over Kafka. The idea is to make the Kafka
messages similar to http in that they would consist of headers and a body.
The body would be json.
On Mon, May 6, 2019 at 6:13 PM John Dale wrote:
> You could try debugging the tomcat code and find out how, right after
> it parses the TCP request, it invokes the servlet. You can then
> create your own harness for tomcat code after initializing the
> appropriate context for the request to tomcat. I don't know off hand
> where in the tomcat code this cut point can be found.
>
> Is this a performance issue, or are you building a proxy?
>
> What is the problem you're trying to solve?
>
> On 5/6/19, Paul Carter-Brown wrote:
> > Yea, but the issue is that only works when calling in the context of a
> > current servlet call.
> >
> > Here is the kind of problem I want to solve:
> >
> > @WebServlet(name = "MyExample", urlPatterns = {"/example"},
> loadOnStartup =
> > 1)
> > public class Example extends HttpServlet {
> >
> > @PersistenceContext
> > private EntityManager em;
> >
> > @Override
> > public void init(ServletConfig config) {
> > Thread t = new Thread(() -> {
> > while (true) {
> > try {
> > // Do a GET to /example/ and get the response without
> > going out on localhost and back in
> > // We cant just call doGet as we want the request to
> > flow through the servlet filters, do the entitymanager injection etc
> > Thread.sleep(1);
> > } catch (Exception e) {
> > }
> > }
> > });
> > t.start();
> >
> > }
> >
> > @Override
> > protected void doGet(HttpServletRequest req, HttpServletResponse
> resp)
> > throws ServletException, IOException {
> > // do stuff like use em
> > resp.setStatus(200);
> > resp.getWriter().write("Hello World");
> > }
> >
> > }
> >
> >
> >
> >
> > On Mon, May 6, 2019 at 5:35 PM John Dale wrote:
> >
> >> For reference, I did find this after searching "calling a servlet
> >> programmatically":
> >> https://docs.oracle.com/cd/E19146-01/819-2634/abxbn/index.html
> >>
> >> On 5/6/19, Paul Carter-Brown wrote:
> >> > I think we are completely missing each other. Forget sockets - that
> was
> >> > just an example. I have code running in a Tomcat App server which is
> >> > not
> >> > managed by Tomcat and is not initiated by anything within Tomcat. That
> >> code
> >> > now wants to call a servlet hosted in that very same JVM. Any way to
> do
> >> > that without going out and back in on TCP?
> >> >
> >> >
> >> > On Mon, May 6, 2019 at 5:14 PM John Dale wrote:
> >> >
> >> >> Sockets are an implementation of TCP/UDP inherently.
> >> >>
> >> >> Perhaps a mountaintop signal fire?
> >> >>
> >> >> ;)
> >> >>
> >> >> John
> >> >>
> >> >>
> >> >> On 5/6/19, Paul Carter-Brown wrote:
> >> >> > lol on the Semaphore Telegraph,
> >> >> >
> >> >> > I can't use a request dispatcher as the request is being initiated
> >> from
> >> >> > code that has no context. I already have it working with HTTP using
> >> >> > asynchttp library, but I want to avoid the overhead. E.g. lets say
> I
> >> >> wrote
> >> >> > my own server socket listener on port 1 running in the Tomcat
> >> >> > JVM
> >> >> > and
> >> >> > got some request in some propriatary protocol called X. Now I want
> >> >> > to
> >> >> call
> >> >> > a Tomcat servlet in the current JVM with some info I got over X
> >> without
> >> >> > going out on TCP and back in
> >> >> >
> >> >> > On Mon, May 6, 2019 at 4:40 PM John Dale
> wrote:
> >> >> >
> >> >> >> If you're wanting to forward control to another servlet deployed
> in
> >> >> >> the same context:
> >> >> >> https://www.javatpoint.com/requestdispatcher-in-servlet
> >> >> >>
> >> >> >> If you are okay going through TCP to facilitate some future or
> >> current
> >> >> >> distribution of services, Use HTTPURLConnection (not sure what
> >> >> >> you're
> >> >> >> wanting to do with the result of the request, if anything):
> >> >> >>
> >> >> >>
> >> >>
> >>
> https://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests
> >> >> >>
> >> >> >> If you need more sophisticated HTTP interactions, Apache maintains
> >> >> >> a
> >> >> >> very useful library for that: http://hc.apache.org/
> >> >> >>
> >> >> >> If these don't work-out for you, rather than using .NET, PHP,
> >> >> >> Python,
> >> >> >> or some other J
Re: Initiating httpservletrequest from inside Tomcat / TomEE
You could try debugging the tomcat code and find out how, right after
it parses the TCP request, it invokes the servlet. You can then
create your own harness for tomcat code after initializing the
appropriate context for the request to tomcat. I don't know off hand
where in the tomcat code this cut point can be found.
Is this a performance issue, or are you building a proxy?
What is the problem you're trying to solve?
On 5/6/19, Paul Carter-Brown wrote:
> Yea, but the issue is that only works when calling in the context of a
> current servlet call.
>
> Here is the kind of problem I want to solve:
>
> @WebServlet(name = "MyExample", urlPatterns = {"/example"}, loadOnStartup =
> 1)
> public class Example extends HttpServlet {
>
> @PersistenceContext
> private EntityManager em;
>
> @Override
> public void init(ServletConfig config) {
> Thread t = new Thread(() -> {
> while (true) {
> try {
> // Do a GET to /example/ and get the response without
> going out on localhost and back in
> // We cant just call doGet as we want the request to
> flow through the servlet filters, do the entitymanager injection etc
> Thread.sleep(1);
> } catch (Exception e) {
> }
> }
> });
> t.start();
>
> }
>
> @Override
> protected void doGet(HttpServletRequest req, HttpServletResponse resp)
> throws ServletException, IOException {
> // do stuff like use em
> resp.setStatus(200);
> resp.getWriter().write("Hello World");
> }
>
> }
>
>
>
>
> On Mon, May 6, 2019 at 5:35 PM John Dale wrote:
>
>> For reference, I did find this after searching "calling a servlet
>> programmatically":
>> https://docs.oracle.com/cd/E19146-01/819-2634/abxbn/index.html
>>
>> On 5/6/19, Paul Carter-Brown wrote:
>> > I think we are completely missing each other. Forget sockets - that was
>> > just an example. I have code running in a Tomcat App server which is
>> > not
>> > managed by Tomcat and is not initiated by anything within Tomcat. That
>> code
>> > now wants to call a servlet hosted in that very same JVM. Any way to do
>> > that without going out and back in on TCP?
>> >
>> >
>> > On Mon, May 6, 2019 at 5:14 PM John Dale wrote:
>> >
>> >> Sockets are an implementation of TCP/UDP inherently.
>> >>
>> >> Perhaps a mountaintop signal fire?
>> >>
>> >> ;)
>> >>
>> >> John
>> >>
>> >>
>> >> On 5/6/19, Paul Carter-Brown wrote:
>> >> > lol on the Semaphore Telegraph,
>> >> >
>> >> > I can't use a request dispatcher as the request is being initiated
>> from
>> >> > code that has no context. I already have it working with HTTP using
>> >> > asynchttp library, but I want to avoid the overhead. E.g. lets say I
>> >> wrote
>> >> > my own server socket listener on port 1 running in the Tomcat
>> >> > JVM
>> >> > and
>> >> > got some request in some propriatary protocol called X. Now I want
>> >> > to
>> >> call
>> >> > a Tomcat servlet in the current JVM with some info I got over X
>> without
>> >> > going out on TCP and back in
>> >> >
>> >> > On Mon, May 6, 2019 at 4:40 PM John Dale wrote:
>> >> >
>> >> >> If you're wanting to forward control to another servlet deployed in
>> >> >> the same context:
>> >> >> https://www.javatpoint.com/requestdispatcher-in-servlet
>> >> >>
>> >> >> If you are okay going through TCP to facilitate some future or
>> current
>> >> >> distribution of services, Use HTTPURLConnection (not sure what
>> >> >> you're
>> >> >> wanting to do with the result of the request, if anything):
>> >> >>
>> >> >>
>> >>
>> https://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests
>> >> >>
>> >> >> If you need more sophisticated HTTP interactions, Apache maintains
>> >> >> a
>> >> >> very useful library for that: http://hc.apache.org/
>> >> >>
>> >> >> If these don't work-out for you, rather than using .NET, PHP,
>> >> >> Python,
>> >> >> or some other Java facsimile at best, I recommend using the
>> >> >> semaphore
>> >> >> telegraph:
>> >> >> https://en.wikipedia.org/wiki/Semaphore_telegraph
>> >> >>
>> >> >> Sincerely,
>> >> >>
>> >> >> John
>> >> >> DB2DOM
>> >> >>
>> >> >> On 5/6/19, Paul Carter-Brown wrote:
>> >> >> > Hi John,
>> >> >> >
>> >> >> > Thanks for your feedback.
>> >> >> >
>> >> >> > The request I'm initiating should not or need not carry any
>> >> >> > context
>> >> >> > from
>> >> >> > the originating code. There is also no session to worry about as
>> its
>> >> >> > just
>> >> >> > for rest calls. So basically I have the headers, path and body
>> >> >> > and
>> >> need
>> >> >> to
>> >> >> > generate a http servlet request and get an http servlet response
>> (or
>> >> >> > similar) back. I have this working by calling into localhost but
>> >> >> > ideally
>> >> >> > want to skip the trombone out and back in.
>> >> >> >
>> >> >> > Have you got any
Re: Initiating httpservletrequest from inside Tomcat / TomEE
Yea, but the issue is that only works when calling in the context of a
current servlet call.
Here is the kind of problem I want to solve:
@WebServlet(name = "MyExample", urlPatterns = {"/example"}, loadOnStartup =
1)
public class Example extends HttpServlet {
@PersistenceContext
private EntityManager em;
@Override
public void init(ServletConfig config) {
Thread t = new Thread(() -> {
while (true) {
try {
// Do a GET to /example/ and get the response without
going out on localhost and back in
// We cant just call doGet as we want the request to
flow through the servlet filters, do the entitymanager injection etc
Thread.sleep(1);
} catch (Exception e) {
}
}
});
t.start();
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// do stuff like use em
resp.setStatus(200);
resp.getWriter().write("Hello World");
}
}
On Mon, May 6, 2019 at 5:35 PM John Dale wrote:
> For reference, I did find this after searching "calling a servlet
> programmatically":
> https://docs.oracle.com/cd/E19146-01/819-2634/abxbn/index.html
>
> On 5/6/19, Paul Carter-Brown wrote:
> > I think we are completely missing each other. Forget sockets - that was
> > just an example. I have code running in a Tomcat App server which is not
> > managed by Tomcat and is not initiated by anything within Tomcat. That
> code
> > now wants to call a servlet hosted in that very same JVM. Any way to do
> > that without going out and back in on TCP?
> >
> >
> > On Mon, May 6, 2019 at 5:14 PM John Dale wrote:
> >
> >> Sockets are an implementation of TCP/UDP inherently.
> >>
> >> Perhaps a mountaintop signal fire?
> >>
> >> ;)
> >>
> >> John
> >>
> >>
> >> On 5/6/19, Paul Carter-Brown wrote:
> >> > lol on the Semaphore Telegraph,
> >> >
> >> > I can't use a request dispatcher as the request is being initiated
> from
> >> > code that has no context. I already have it working with HTTP using
> >> > asynchttp library, but I want to avoid the overhead. E.g. lets say I
> >> wrote
> >> > my own server socket listener on port 1 running in the Tomcat JVM
> >> > and
> >> > got some request in some propriatary protocol called X. Now I want to
> >> call
> >> > a Tomcat servlet in the current JVM with some info I got over X
> without
> >> > going out on TCP and back in
> >> >
> >> > On Mon, May 6, 2019 at 4:40 PM John Dale wrote:
> >> >
> >> >> If you're wanting to forward control to another servlet deployed in
> >> >> the same context:
> >> >> https://www.javatpoint.com/requestdispatcher-in-servlet
> >> >>
> >> >> If you are okay going through TCP to facilitate some future or
> current
> >> >> distribution of services, Use HTTPURLConnection (not sure what you're
> >> >> wanting to do with the result of the request, if anything):
> >> >>
> >> >>
> >>
> https://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests
> >> >>
> >> >> If you need more sophisticated HTTP interactions, Apache maintains a
> >> >> very useful library for that: http://hc.apache.org/
> >> >>
> >> >> If these don't work-out for you, rather than using .NET, PHP, Python,
> >> >> or some other Java facsimile at best, I recommend using the semaphore
> >> >> telegraph:
> >> >> https://en.wikipedia.org/wiki/Semaphore_telegraph
> >> >>
> >> >> Sincerely,
> >> >>
> >> >> John
> >> >> DB2DOM
> >> >>
> >> >> On 5/6/19, Paul Carter-Brown wrote:
> >> >> > Hi John,
> >> >> >
> >> >> > Thanks for your feedback.
> >> >> >
> >> >> > The request I'm initiating should not or need not carry any context
> >> >> > from
> >> >> > the originating code. There is also no session to worry about as
> its
> >> >> > just
> >> >> > for rest calls. So basically I have the headers, path and body and
> >> need
> >> >> to
> >> >> > generate a http servlet request and get an http servlet response
> (or
> >> >> > similar) back. I have this working by calling into localhost but
> >> >> > ideally
> >> >> > want to skip the trombone out and back in.
> >> >> >
> >> >> > Have you got any basic code examples?
> >> >> >
> >> >> > Paul
> >> >> >
> >> >> > On Tue, Apr 30, 2019 at 5:27 PM John Dale
> wrote:
> >> >> >
> >> >> >> Another thought .. you can do some request dispatching, but
> without
> >> >> >> knowing more about the tools you're using, I can't say for sure if
> >> >> >> this is the direction you'll want to go.
> >> >> >>
> >> >> >> On 4/29/19, Paul Carter-Brown
> wrote:
> >> >> >> > Hi
> >> >> >> >
> >> >> >> > I'm trying to design a Kafka consumer and producer that will run
> >> >> inside
> >> >> >> the
> >> >> >> > tomcat jvm and pick up messages off a Kafka topic and translate
> >> them
> >> >> >> into a
> >> >> >> > servlet request and pass it through tomcat and then w
Re: Initiating httpservletrequest from inside Tomcat / TomEE
For reference, I did find this after searching "calling a servlet programmatically": https://docs.oracle.com/cd/E19146-01/819-2634/abxbn/index.html On 5/6/19, Paul Carter-Brown wrote: > I think we are completely missing each other. Forget sockets - that was > just an example. I have code running in a Tomcat App server which is not > managed by Tomcat and is not initiated by anything within Tomcat. That code > now wants to call a servlet hosted in that very same JVM. Any way to do > that without going out and back in on TCP? > > > On Mon, May 6, 2019 at 5:14 PM John Dale wrote: > >> Sockets are an implementation of TCP/UDP inherently. >> >> Perhaps a mountaintop signal fire? >> >> ;) >> >> John >> >> >> On 5/6/19, Paul Carter-Brown wrote: >> > lol on the Semaphore Telegraph, >> > >> > I can't use a request dispatcher as the request is being initiated from >> > code that has no context. I already have it working with HTTP using >> > asynchttp library, but I want to avoid the overhead. E.g. lets say I >> wrote >> > my own server socket listener on port 1 running in the Tomcat JVM >> > and >> > got some request in some propriatary protocol called X. Now I want to >> call >> > a Tomcat servlet in the current JVM with some info I got over X without >> > going out on TCP and back in >> > >> > On Mon, May 6, 2019 at 4:40 PM John Dale wrote: >> > >> >> If you're wanting to forward control to another servlet deployed in >> >> the same context: >> >> https://www.javatpoint.com/requestdispatcher-in-servlet >> >> >> >> If you are okay going through TCP to facilitate some future or current >> >> distribution of services, Use HTTPURLConnection (not sure what you're >> >> wanting to do with the result of the request, if anything): >> >> >> >> >> https://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests >> >> >> >> If you need more sophisticated HTTP interactions, Apache maintains a >> >> very useful library for that: http://hc.apache.org/ >> >> >> >> If these don't work-out for you, rather than using .NET, PHP, Python, >> >> or some other Java facsimile at best, I recommend using the semaphore >> >> telegraph: >> >> https://en.wikipedia.org/wiki/Semaphore_telegraph >> >> >> >> Sincerely, >> >> >> >> John >> >> DB2DOM >> >> >> >> On 5/6/19, Paul Carter-Brown wrote: >> >> > Hi John, >> >> > >> >> > Thanks for your feedback. >> >> > >> >> > The request I'm initiating should not or need not carry any context >> >> > from >> >> > the originating code. There is also no session to worry about as its >> >> > just >> >> > for rest calls. So basically I have the headers, path and body and >> need >> >> to >> >> > generate a http servlet request and get an http servlet response (or >> >> > similar) back. I have this working by calling into localhost but >> >> > ideally >> >> > want to skip the trombone out and back in. >> >> > >> >> > Have you got any basic code examples? >> >> > >> >> > Paul >> >> > >> >> > On Tue, Apr 30, 2019 at 5:27 PM John Dale wrote: >> >> > >> >> >> Another thought .. you can do some request dispatching, but without >> >> >> knowing more about the tools you're using, I can't say for sure if >> >> >> this is the direction you'll want to go. >> >> >> >> >> >> On 4/29/19, Paul Carter-Brown wrote: >> >> >> > Hi >> >> >> > >> >> >> > I'm trying to design a Kafka consumer and producer that will run >> >> inside >> >> >> the >> >> >> > tomcat jvm and pick up messages off a Kafka topic and translate >> them >> >> >> into a >> >> >> > servlet request and pass it through tomcat and then when the >> >> >> > response >> >> >> > is >> >> >> > complete then translate it into a Kafka message and put it onto >> >> another >> >> >> > topic as a reply. This way I can reuse our existing jax-rs rest >> >> >> > services >> >> >> > and expose them as an async api over Kafka. The idea is to make >> >> >> > the >> >> >> > Kafka >> >> >> > messages similar to http in that they would consist of headers >> >> >> > and >> a >> >> >> body. >> >> >> > The body would be json. >> >> >> > >> >> >> > Now I know this could be done by calling localhost with an http >> call >> >> to >> >> >> > trombone the requests back into tomcat but I'd like to avoid the >> >> >> associated >> >> >> > latency and overhead. Is it possible to call tomcat directly >> >> >> > in-process. >> >> >> > This does not need to be portable to other containers so can be >> >> >> > proprietary. >> >> >> > >> >> >> > I'm using tomcat 8. In fact its tomee 8 but guessed this is more >> >> >> > a >> >> >> > tomcat >> >> >> > question than tomee but have sent to both groups just in case. >> >> >> > >> >> >> > Thanks for any insights. >> >> >> > >> >> >> > Paul >> >> >> > >> >> >> >> >> > >> >> >> >> - >> >> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >> >> For additional commands, e-mail: users-h...@tomcat.apache.org >> >> >>
Re: Initiating httpservletrequest from inside Tomcat / TomEE
Another thought is that servlets maintain contextual information and resources .. that's nice, saves a lot of time. As soon as you need a database resource or an extension of your pruned-back HTTP implementation on the server socket, you'll be rebuilding what Tomcat has already done? On 5/6/19, Paul Carter-Brown wrote: > lol on the Semaphore Telegraph, > > I can't use a request dispatcher as the request is being initiated from > code that has no context. I already have it working with HTTP using > asynchttp library, but I want to avoid the overhead. E.g. lets say I wrote > my own server socket listener on port 1 running in the Tomcat JVM and > got some request in some propriatary protocol called X. Now I want to call > a Tomcat servlet in the current JVM with some info I got over X without > going out on TCP and back in > > On Mon, May 6, 2019 at 4:40 PM John Dale wrote: > >> If you're wanting to forward control to another servlet deployed in >> the same context: >> https://www.javatpoint.com/requestdispatcher-in-servlet >> >> If you are okay going through TCP to facilitate some future or current >> distribution of services, Use HTTPURLConnection (not sure what you're >> wanting to do with the result of the request, if anything): >> >> https://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests >> >> If you need more sophisticated HTTP interactions, Apache maintains a >> very useful library for that: http://hc.apache.org/ >> >> If these don't work-out for you, rather than using .NET, PHP, Python, >> or some other Java facsimile at best, I recommend using the semaphore >> telegraph: >> https://en.wikipedia.org/wiki/Semaphore_telegraph >> >> Sincerely, >> >> John >> DB2DOM >> >> On 5/6/19, Paul Carter-Brown wrote: >> > Hi John, >> > >> > Thanks for your feedback. >> > >> > The request I'm initiating should not or need not carry any context >> > from >> > the originating code. There is also no session to worry about as its >> > just >> > for rest calls. So basically I have the headers, path and body and need >> to >> > generate a http servlet request and get an http servlet response (or >> > similar) back. I have this working by calling into localhost but >> > ideally >> > want to skip the trombone out and back in. >> > >> > Have you got any basic code examples? >> > >> > Paul >> > >> > On Tue, Apr 30, 2019 at 5:27 PM John Dale wrote: >> > >> >> Another thought .. you can do some request dispatching, but without >> >> knowing more about the tools you're using, I can't say for sure if >> >> this is the direction you'll want to go. >> >> >> >> On 4/29/19, Paul Carter-Brown wrote: >> >> > Hi >> >> > >> >> > I'm trying to design a Kafka consumer and producer that will run >> inside >> >> the >> >> > tomcat jvm and pick up messages off a Kafka topic and translate them >> >> into a >> >> > servlet request and pass it through tomcat and then when the >> >> > response >> >> > is >> >> > complete then translate it into a Kafka message and put it onto >> another >> >> > topic as a reply. This way I can reuse our existing jax-rs rest >> >> > services >> >> > and expose them as an async api over Kafka. The idea is to make the >> >> > Kafka >> >> > messages similar to http in that they would consist of headers and a >> >> body. >> >> > The body would be json. >> >> > >> >> > Now I know this could be done by calling localhost with an http call >> to >> >> > trombone the requests back into tomcat but I'd like to avoid the >> >> associated >> >> > latency and overhead. Is it possible to call tomcat directly >> >> > in-process. >> >> > This does not need to be portable to other containers so can be >> >> > proprietary. >> >> > >> >> > I'm using tomcat 8. In fact its tomee 8 but guessed this is more a >> >> > tomcat >> >> > question than tomee but have sent to both groups just in case. >> >> > >> >> > Thanks for any insights. >> >> > >> >> > Paul >> >> > >> >> >> > >> >> - >> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >> For additional commands, e-mail: users-h...@tomcat.apache.org >> >> > - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Initiating httpservletrequest from inside Tomcat / TomEE
Class loaders maintain isolation of contexts, so calling a method on a different servlet can be tricky, but that is possible. Although, take into account that the container maintains pools of servlets, so something like a static service method, assuming you can crack the class loader nut, might work. In the design of your service, you would need to define (possibly static) methods that encapsulate the functionality you'd like to execute (reuse). Without doing something that would be considered a violation of security principles in computing (SPECTR notwithstanding), I think you'll have a very difficult time with this requirement. The JVM may be doing some optimizations for localhost requests that speed things up, but I can't confirm that at present (and my instincts say it isn't). This brings up the point about performance vs scalability. When you are proxying network requests like this, scalability can keep your request/processing times normative (assuming you don't have a database problem). Assuming your baseline request/response times are acceptable, using scalability techniques is generally preferred to unrelenting performance optimizations not including memory leaks. That said, I get your sentiment, and applaud your desire to make things go fast. Awesome! On 5/6/19, Paul Carter-Brown wrote: > I think we are completely missing each other. Forget sockets - that was > just an example. I have code running in a Tomcat App server which is not > managed by Tomcat and is not initiated by anything within Tomcat. That code > now wants to call a servlet hosted in that very same JVM. Any way to do > that without going out and back in on TCP? > > > On Mon, May 6, 2019 at 5:14 PM John Dale wrote: > >> Sockets are an implementation of TCP/UDP inherently. >> >> Perhaps a mountaintop signal fire? >> >> ;) >> >> John >> >> >> On 5/6/19, Paul Carter-Brown wrote: >> > lol on the Semaphore Telegraph, >> > >> > I can't use a request dispatcher as the request is being initiated from >> > code that has no context. I already have it working with HTTP using >> > asynchttp library, but I want to avoid the overhead. E.g. lets say I >> wrote >> > my own server socket listener on port 1 running in the Tomcat JVM >> > and >> > got some request in some propriatary protocol called X. Now I want to >> call >> > a Tomcat servlet in the current JVM with some info I got over X without >> > going out on TCP and back in >> > >> > On Mon, May 6, 2019 at 4:40 PM John Dale wrote: >> > >> >> If you're wanting to forward control to another servlet deployed in >> >> the same context: >> >> https://www.javatpoint.com/requestdispatcher-in-servlet >> >> >> >> If you are okay going through TCP to facilitate some future or current >> >> distribution of services, Use HTTPURLConnection (not sure what you're >> >> wanting to do with the result of the request, if anything): >> >> >> >> >> https://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests >> >> >> >> If you need more sophisticated HTTP interactions, Apache maintains a >> >> very useful library for that: http://hc.apache.org/ >> >> >> >> If these don't work-out for you, rather than using .NET, PHP, Python, >> >> or some other Java facsimile at best, I recommend using the semaphore >> >> telegraph: >> >> https://en.wikipedia.org/wiki/Semaphore_telegraph >> >> >> >> Sincerely, >> >> >> >> John >> >> DB2DOM >> >> >> >> On 5/6/19, Paul Carter-Brown wrote: >> >> > Hi John, >> >> > >> >> > Thanks for your feedback. >> >> > >> >> > The request I'm initiating should not or need not carry any context >> >> > from >> >> > the originating code. There is also no session to worry about as its >> >> > just >> >> > for rest calls. So basically I have the headers, path and body and >> need >> >> to >> >> > generate a http servlet request and get an http servlet response (or >> >> > similar) back. I have this working by calling into localhost but >> >> > ideally >> >> > want to skip the trombone out and back in. >> >> > >> >> > Have you got any basic code examples? >> >> > >> >> > Paul >> >> > >> >> > On Tue, Apr 30, 2019 at 5:27 PM John Dale wrote: >> >> > >> >> >> Another thought .. you can do some request dispatching, but without >> >> >> knowing more about the tools you're using, I can't say for sure if >> >> >> this is the direction you'll want to go. >> >> >> >> >> >> On 4/29/19, Paul Carter-Brown wrote: >> >> >> > Hi >> >> >> > >> >> >> > I'm trying to design a Kafka consumer and producer that will run >> >> inside >> >> >> the >> >> >> > tomcat jvm and pick up messages off a Kafka topic and translate >> them >> >> >> into a >> >> >> > servlet request and pass it through tomcat and then when the >> >> >> > response >> >> >> > is >> >> >> > complete then translate it into a Kafka message and put it onto >> >> another >> >> >> > topic as a reply. This way I can reuse our existing jax-rs rest >> >> >> > services >> >> >> > and expose
Re: Initiating httpservletrequest from inside Tomcat / TomEE
I think we are completely missing each other. Forget sockets - that was just an example. I have code running in a Tomcat App server which is not managed by Tomcat and is not initiated by anything within Tomcat. That code now wants to call a servlet hosted in that very same JVM. Any way to do that without going out and back in on TCP? On Mon, May 6, 2019 at 5:14 PM John Dale wrote: > Sockets are an implementation of TCP/UDP inherently. > > Perhaps a mountaintop signal fire? > > ;) > > John > > > On 5/6/19, Paul Carter-Brown wrote: > > lol on the Semaphore Telegraph, > > > > I can't use a request dispatcher as the request is being initiated from > > code that has no context. I already have it working with HTTP using > > asynchttp library, but I want to avoid the overhead. E.g. lets say I > wrote > > my own server socket listener on port 1 running in the Tomcat JVM and > > got some request in some propriatary protocol called X. Now I want to > call > > a Tomcat servlet in the current JVM with some info I got over X without > > going out on TCP and back in > > > > On Mon, May 6, 2019 at 4:40 PM John Dale wrote: > > > >> If you're wanting to forward control to another servlet deployed in > >> the same context: > >> https://www.javatpoint.com/requestdispatcher-in-servlet > >> > >> If you are okay going through TCP to facilitate some future or current > >> distribution of services, Use HTTPURLConnection (not sure what you're > >> wanting to do with the result of the request, if anything): > >> > >> > https://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests > >> > >> If you need more sophisticated HTTP interactions, Apache maintains a > >> very useful library for that: http://hc.apache.org/ > >> > >> If these don't work-out for you, rather than using .NET, PHP, Python, > >> or some other Java facsimile at best, I recommend using the semaphore > >> telegraph: > >> https://en.wikipedia.org/wiki/Semaphore_telegraph > >> > >> Sincerely, > >> > >> John > >> DB2DOM > >> > >> On 5/6/19, Paul Carter-Brown wrote: > >> > Hi John, > >> > > >> > Thanks for your feedback. > >> > > >> > The request I'm initiating should not or need not carry any context > >> > from > >> > the originating code. There is also no session to worry about as its > >> > just > >> > for rest calls. So basically I have the headers, path and body and > need > >> to > >> > generate a http servlet request and get an http servlet response (or > >> > similar) back. I have this working by calling into localhost but > >> > ideally > >> > want to skip the trombone out and back in. > >> > > >> > Have you got any basic code examples? > >> > > >> > Paul > >> > > >> > On Tue, Apr 30, 2019 at 5:27 PM John Dale wrote: > >> > > >> >> Another thought .. you can do some request dispatching, but without > >> >> knowing more about the tools you're using, I can't say for sure if > >> >> this is the direction you'll want to go. > >> >> > >> >> On 4/29/19, Paul Carter-Brown wrote: > >> >> > Hi > >> >> > > >> >> > I'm trying to design a Kafka consumer and producer that will run > >> inside > >> >> the > >> >> > tomcat jvm and pick up messages off a Kafka topic and translate > them > >> >> into a > >> >> > servlet request and pass it through tomcat and then when the > >> >> > response > >> >> > is > >> >> > complete then translate it into a Kafka message and put it onto > >> another > >> >> > topic as a reply. This way I can reuse our existing jax-rs rest > >> >> > services > >> >> > and expose them as an async api over Kafka. The idea is to make the > >> >> > Kafka > >> >> > messages similar to http in that they would consist of headers and > a > >> >> body. > >> >> > The body would be json. > >> >> > > >> >> > Now I know this could be done by calling localhost with an http > call > >> to > >> >> > trombone the requests back into tomcat but I'd like to avoid the > >> >> associated > >> >> > latency and overhead. Is it possible to call tomcat directly > >> >> > in-process. > >> >> > This does not need to be portable to other containers so can be > >> >> > proprietary. > >> >> > > >> >> > I'm using tomcat 8. In fact its tomee 8 but guessed this is more a > >> >> > tomcat > >> >> > question than tomee but have sent to both groups just in case. > >> >> > > >> >> > Thanks for any insights. > >> >> > > >> >> > Paul > >> >> > > >> >> > >> > > >> > >> - > >> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > >> For additional commands, e-mail: users-h...@tomcat.apache.org > >> > >> > > > > - > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > >
Re: Initiating httpservletrequest from inside Tomcat / TomEE
Sockets are an implementation of TCP/UDP inherently. Perhaps a mountaintop signal fire? ;) John On 5/6/19, Paul Carter-Brown wrote: > lol on the Semaphore Telegraph, > > I can't use a request dispatcher as the request is being initiated from > code that has no context. I already have it working with HTTP using > asynchttp library, but I want to avoid the overhead. E.g. lets say I wrote > my own server socket listener on port 1 running in the Tomcat JVM and > got some request in some propriatary protocol called X. Now I want to call > a Tomcat servlet in the current JVM with some info I got over X without > going out on TCP and back in > > On Mon, May 6, 2019 at 4:40 PM John Dale wrote: > >> If you're wanting to forward control to another servlet deployed in >> the same context: >> https://www.javatpoint.com/requestdispatcher-in-servlet >> >> If you are okay going through TCP to facilitate some future or current >> distribution of services, Use HTTPURLConnection (not sure what you're >> wanting to do with the result of the request, if anything): >> >> https://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests >> >> If you need more sophisticated HTTP interactions, Apache maintains a >> very useful library for that: http://hc.apache.org/ >> >> If these don't work-out for you, rather than using .NET, PHP, Python, >> or some other Java facsimile at best, I recommend using the semaphore >> telegraph: >> https://en.wikipedia.org/wiki/Semaphore_telegraph >> >> Sincerely, >> >> John >> DB2DOM >> >> On 5/6/19, Paul Carter-Brown wrote: >> > Hi John, >> > >> > Thanks for your feedback. >> > >> > The request I'm initiating should not or need not carry any context >> > from >> > the originating code. There is also no session to worry about as its >> > just >> > for rest calls. So basically I have the headers, path and body and need >> to >> > generate a http servlet request and get an http servlet response (or >> > similar) back. I have this working by calling into localhost but >> > ideally >> > want to skip the trombone out and back in. >> > >> > Have you got any basic code examples? >> > >> > Paul >> > >> > On Tue, Apr 30, 2019 at 5:27 PM John Dale wrote: >> > >> >> Another thought .. you can do some request dispatching, but without >> >> knowing more about the tools you're using, I can't say for sure if >> >> this is the direction you'll want to go. >> >> >> >> On 4/29/19, Paul Carter-Brown wrote: >> >> > Hi >> >> > >> >> > I'm trying to design a Kafka consumer and producer that will run >> inside >> >> the >> >> > tomcat jvm and pick up messages off a Kafka topic and translate them >> >> into a >> >> > servlet request and pass it through tomcat and then when the >> >> > response >> >> > is >> >> > complete then translate it into a Kafka message and put it onto >> another >> >> > topic as a reply. This way I can reuse our existing jax-rs rest >> >> > services >> >> > and expose them as an async api over Kafka. The idea is to make the >> >> > Kafka >> >> > messages similar to http in that they would consist of headers and a >> >> body. >> >> > The body would be json. >> >> > >> >> > Now I know this could be done by calling localhost with an http call >> to >> >> > trombone the requests back into tomcat but I'd like to avoid the >> >> associated >> >> > latency and overhead. Is it possible to call tomcat directly >> >> > in-process. >> >> > This does not need to be portable to other containers so can be >> >> > proprietary. >> >> > >> >> > I'm using tomcat 8. In fact its tomee 8 but guessed this is more a >> >> > tomcat >> >> > question than tomee but have sent to both groups just in case. >> >> > >> >> > Thanks for any insights. >> >> > >> >> > Paul >> >> > >> >> >> > >> >> - >> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >> For additional commands, e-mail: users-h...@tomcat.apache.org >> >> > - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Initiating httpservletrequest from inside Tomcat / TomEE
lol on the Semaphore Telegraph, I can't use a request dispatcher as the request is being initiated from code that has no context. I already have it working with HTTP using asynchttp library, but I want to avoid the overhead. E.g. lets say I wrote my own server socket listener on port 1 running in the Tomcat JVM and got some request in some propriatary protocol called X. Now I want to call a Tomcat servlet in the current JVM with some info I got over X without going out on TCP and back in On Mon, May 6, 2019 at 4:40 PM John Dale wrote: > If you're wanting to forward control to another servlet deployed in > the same context: > https://www.javatpoint.com/requestdispatcher-in-servlet > > If you are okay going through TCP to facilitate some future or current > distribution of services, Use HTTPURLConnection (not sure what you're > wanting to do with the result of the request, if anything): > > https://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests > > If you need more sophisticated HTTP interactions, Apache maintains a > very useful library for that: http://hc.apache.org/ > > If these don't work-out for you, rather than using .NET, PHP, Python, > or some other Java facsimile at best, I recommend using the semaphore > telegraph: > https://en.wikipedia.org/wiki/Semaphore_telegraph > > Sincerely, > > John > DB2DOM > > On 5/6/19, Paul Carter-Brown wrote: > > Hi John, > > > > Thanks for your feedback. > > > > The request I'm initiating should not or need not carry any context from > > the originating code. There is also no session to worry about as its just > > for rest calls. So basically I have the headers, path and body and need > to > > generate a http servlet request and get an http servlet response (or > > similar) back. I have this working by calling into localhost but ideally > > want to skip the trombone out and back in. > > > > Have you got any basic code examples? > > > > Paul > > > > On Tue, Apr 30, 2019 at 5:27 PM John Dale wrote: > > > >> Another thought .. you can do some request dispatching, but without > >> knowing more about the tools you're using, I can't say for sure if > >> this is the direction you'll want to go. > >> > >> On 4/29/19, Paul Carter-Brown wrote: > >> > Hi > >> > > >> > I'm trying to design a Kafka consumer and producer that will run > inside > >> the > >> > tomcat jvm and pick up messages off a Kafka topic and translate them > >> into a > >> > servlet request and pass it through tomcat and then when the response > >> > is > >> > complete then translate it into a Kafka message and put it onto > another > >> > topic as a reply. This way I can reuse our existing jax-rs rest > >> > services > >> > and expose them as an async api over Kafka. The idea is to make the > >> > Kafka > >> > messages similar to http in that they would consist of headers and a > >> body. > >> > The body would be json. > >> > > >> > Now I know this could be done by calling localhost with an http call > to > >> > trombone the requests back into tomcat but I'd like to avoid the > >> associated > >> > latency and overhead. Is it possible to call tomcat directly > >> > in-process. > >> > This does not need to be portable to other containers so can be > >> > proprietary. > >> > > >> > I'm using tomcat 8. In fact its tomee 8 but guessed this is more a > >> > tomcat > >> > question than tomee but have sent to both groups just in case. > >> > > >> > Thanks for any insights. > >> > > >> > Paul > >> > > >> > > > > - > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > >
Re: Initiating httpservletrequest from inside Tomcat / TomEE
If you're wanting to forward control to another servlet deployed in the same context: https://www.javatpoint.com/requestdispatcher-in-servlet If you are okay going through TCP to facilitate some future or current distribution of services, Use HTTPURLConnection (not sure what you're wanting to do with the result of the request, if anything): https://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests If you need more sophisticated HTTP interactions, Apache maintains a very useful library for that: http://hc.apache.org/ If these don't work-out for you, rather than using .NET, PHP, Python, or some other Java facsimile at best, I recommend using the semaphore telegraph: https://en.wikipedia.org/wiki/Semaphore_telegraph Sincerely, John DB2DOM On 5/6/19, Paul Carter-Brown wrote: > Hi John, > > Thanks for your feedback. > > The request I'm initiating should not or need not carry any context from > the originating code. There is also no session to worry about as its just > for rest calls. So basically I have the headers, path and body and need to > generate a http servlet request and get an http servlet response (or > similar) back. I have this working by calling into localhost but ideally > want to skip the trombone out and back in. > > Have you got any basic code examples? > > Paul > > On Tue, Apr 30, 2019 at 5:27 PM John Dale wrote: > >> Another thought .. you can do some request dispatching, but without >> knowing more about the tools you're using, I can't say for sure if >> this is the direction you'll want to go. >> >> On 4/29/19, Paul Carter-Brown wrote: >> > Hi >> > >> > I'm trying to design a Kafka consumer and producer that will run inside >> the >> > tomcat jvm and pick up messages off a Kafka topic and translate them >> into a >> > servlet request and pass it through tomcat and then when the response >> > is >> > complete then translate it into a Kafka message and put it onto another >> > topic as a reply. This way I can reuse our existing jax-rs rest >> > services >> > and expose them as an async api over Kafka. The idea is to make the >> > Kafka >> > messages similar to http in that they would consist of headers and a >> body. >> > The body would be json. >> > >> > Now I know this could be done by calling localhost with an http call to >> > trombone the requests back into tomcat but I'd like to avoid the >> associated >> > latency and overhead. Is it possible to call tomcat directly >> > in-process. >> > This does not need to be portable to other containers so can be >> > proprietary. >> > >> > I'm using tomcat 8. In fact its tomee 8 but guessed this is more a >> > tomcat >> > question than tomee but have sent to both groups just in case. >> > >> > Thanks for any insights. >> > >> > Paul >> > >> > - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Initiating httpservletrequest from inside Tomcat / TomEE
Hi John, Thanks for your feedback. The request I'm initiating should not or need not carry any context from the originating code. There is also no session to worry about as its just for rest calls. So basically I have the headers, path and body and need to generate a http servlet request and get an http servlet response (or similar) back. I have this working by calling into localhost but ideally want to skip the trombone out and back in. Have you got any basic code examples? Paul On Tue, Apr 30, 2019 at 5:27 PM John Dale wrote: > Another thought .. you can do some request dispatching, but without > knowing more about the tools you're using, I can't say for sure if > this is the direction you'll want to go. > > On 4/29/19, Paul Carter-Brown wrote: > > Hi > > > > I'm trying to design a Kafka consumer and producer that will run inside > the > > tomcat jvm and pick up messages off a Kafka topic and translate them > into a > > servlet request and pass it through tomcat and then when the response is > > complete then translate it into a Kafka message and put it onto another > > topic as a reply. This way I can reuse our existing jax-rs rest services > > and expose them as an async api over Kafka. The idea is to make the Kafka > > messages similar to http in that they would consist of headers and a > body. > > The body would be json. > > > > Now I know this could be done by calling localhost with an http call to > > trombone the requests back into tomcat but I'd like to avoid the > associated > > latency and overhead. Is it possible to call tomcat directly in-process. > > This does not need to be portable to other containers so can be > > proprietary. > > > > I'm using tomcat 8. In fact its tomee 8 but guessed this is more a tomcat > > question than tomee but have sent to both groups just in case. > > > > Thanks for any insights. > > > > Paul > > >
