works for me. Will you create an issue for this.
cheers
</jima>
Thierry Boileau wrote:
Hello,
we had a discussion with Jerome, and we plainly agree with the fact
there is a problem in HttpClientHelper#handle [1] method as pointed out
thanksfully by Adam and Jim.
This method first builds a call object then sends this call and gets the
server's response.
The try/catch block is very problematic in the case the build step of
the call fails. We've decided to remove it.
That is to say that all errors detected in this first step will be in
charge of the caller code which is "responsible to give correct data".
A contrario, the errors detected in the second phase should generate a
status code:
- Status.CONNECTOR_ERROR_XXX (where XXX stands for CONNECTION,
COMMUNICATION and INTERNAL) for all errors detected before the request
is sent. This is the current behaviour.
- HTTP status received from the server.
What do you think about?
best regards,
Thierry Boileau
[1]
public void handle(Request request, Response response) {
try {
HttpClientCall httpCall = getConverter().toSpecific(this,
request);
getConverter().commit(httpCall, request, response);
} catch (Exception e) {
getLogger().log(Level.WARNING,
"Error while handling an HTTP client call: ",
e.getMessage());
getLogger().log(Level.INFO,
"Error while handling an HTTP client call", e);
}
}
I made some comments to the bug, by the way.
One thing that came to mind, about handling different 3rd party client
apis, is to deal with it like Spring deals with JDBC exceptions. In
essence, they wrap and catch the various jdbc/driver exceptions and
then map it to a set of common spring defined exceptions.
In my mind, the Status code in the Response object should be a direct
mapping to the HTTP status codes. This is really the intent you guys
had. Of course, the status code is undefined for a request that
cannot establish a connection with the host, due to various problems
(physical connection, dns, proxy related issues, no route to host, etc.)
Without the ability to "detect" these kind of connectivity issues in
developer code, the Client class is pretty worthless. Having a
generic isError() method or a bogus status code in the response
doesn't give the level of detail needed.
You're also forcing developers to use the nasty pattern of switch or
if/else statements to check for the appropriate conditions in the
Response object. If I'm making multiple requests to the server (which
is common in a RESTful design), and the first call results in a 404
Not Found, I don't want to have to keep checking under each statement
for the various status codes. I just want to have the requests one
per line and get an exception thrown for problems.
This is why I mentioned, in the bug, about the wrapper I use that
throws a UnexpectedStatusException (a custom exception class). The
use of the code looks like this:
try {
Client client = new Client(...);
client.handle(request1, response1, Status.SUCCESS_OK);
client.handle(request2, response2, Status.SUCCESS_OK);
} catch (IOException e) {
// something bad has happened
// like no connection, host name dns failure, etc.
} catch (UnexpectedStatusException e) {
// this is where you can put your if/then checking
if (e.getStatus().equals(Status.CLIENT_ERROR_NOT_FOUND)) {
// 404 Not Found message to user
return;
}
// other handling here, or just some generic handling code
}
Note the additional parameter for the "expected" status in the
handle() method.
Anyway, the point is, you could in theory force all the client related
exceptions into either IOException or UnexpectedStatusException.
Then, you'd have a consistent API for dealing with both HTTP status
code related issues as well as the other connectivity problems related
to the physical connection. Defining handle() to throw both of these
is, in my mind, the right direction.
Adam
Thierry Boileau wrote:
Adam,
I just want to explain why this behaviour happens, not to plainly
justify it.
As you point, it has been decided to show the failures by the way of
the status code and not by the way of the exceptions.
One reason is that for example, the connectors are based on other
externals projects that may throw exceptions of different nature even
for equivalent issues, and the connectors may throw themselves
distinct exceptions for equivalent issues (equivalent from the API's
point of view).
Then, it has seemed difficult to potentially have to catch a growing
list of distinct exceptions in some part of the code (not the whole
code, of course). Thus, it has been decided, and it's a design
choice, to use the status codes instead of the exceptions.
However, this behaviour may be updated, the discussion is open.
best regards,
Thierry Boileau
Oops, didn't see your reply here. I just replied to your other thread.
Actually, I disagree. I think the problem is that the method should
have originally been defined to through checked exceptions.
I want to be to notify the user of the exceptions inside of the client
itself. If my end user has entered a bad url, then I want to be
able to
notify them about that, for example.
Setting a status code is not the way to handle this. You propose
status
code 404, but that's not an appropriate response for a "host not found"
type of problem. Likewise, it's also not an appropriate status code if
the url itself was poorly formed (like, without a leading protocol
scheme).
Anyway, my point is, there are many reason which a request could fail.
I want to see these in my own code so that I can do what's appropriate
with the exception.
Adam
Jim Alateras wrote:
Adam,
I came across the same problem and I believe the problem is more
around not setting the response status code on failure.
cheers
</jima>
Adam Taft wrote:
Here's a test case to look at...
public class TestClass {
public static void main(String[] args) {
try {
Request request = new Request(Method.GET,
"aaaaaaaaaaaaaaaaa");
Client client = new Client(Protocol.HTTP);
client.handle(request);
System.out.println("This code shouldn't
run!");
} catch (Throwable t) {
// eat everything
}
}
}
The offending code is in HttpClientHelper#handle ...
public void handle(Request request, Response response) {
try {
HttpClientCall httpCall =
getConverter().toSpecific(this, request);
getConverter().commit(httpCall, request, response);
} catch (Exception e) {
getLogger().log(Level.WARNING,
"Error while handling an HTTP client call: ",
e.getMessage());
getLogger().log(Level.INFO,
"Error while handling an HTTP client call", e);
}
}
As soon as I get my email confirmation from tigris, I'll file a
bug report. I just wanted to mention this in case there are other
areas you know about with similar code. If the goal is to log the
exception, that's ok, but it needs to be re-thrown.
Thanks!
Adam
