Added WADL file downloading.

obspy/fdsn/client.py

@@ -8,6 +8,11 @@
     GNU Lesser General Public License, Version 3
     (http://www.gnu.org/copyleft/lesser.html)
 """
+from obspy import __version__
+
+import platform
+import Queue
+import threading
 import urllib
 import urllib2
 
@@ -18,13 +23,17 @@
                 }
 SERVICES = ("dataselect", "station", "event")
 
+DEFAULT_USER_AGENT = "ObsPy %s (%s, Python %s)" % (__version__,
+                                                   platform.platform(),
+                                                   platform.python_version())
+
 
 class Client(object):
     """
     FDSN Web service request client.
     """
     def __init__(self, base_url="IRIS", major_version=1, user=None,
-                 password=None):
+                 password=None, user_agent=DEFAULT_USER_AGENT, debug=False):
         """
         Initializes the IRIS Web service client.
 
@@ -40,7 +49,12 @@ def __init__(self, base_url="IRIS", major_version=1, user=None,
         :type password: str
         :param password: Password of HTTP Digest Authentication for access to
             restricted data.
+        :type user_agent: str
+        :param user_agent: The user agent for all requests.
+        :type debug: bool
+        :param debug: Debug flag.
         """
+        self.debug = True
         #if user and password:
             ## Create an OpenerDirector for HTTP Digest Authentication
             #password_mgr = urllib2.HTTPPasswordMgrWithDefaultRealm()
@@ -57,8 +71,13 @@ def __init__(self, base_url="IRIS", major_version=1, user=None,
         # Make sure the base_url does not end with a slash.
         self.base_url = self.base_url.strip("/")
 
+        self.request_headers = {"User-Agent": user_agent}
         self.major_version = major_version
 
+        if self.debug is True:
+            print "Base URL: %s" % self.base_url
+            print "Request Headers: %s" % str(self.request_headers)
+
         self._discover_services()
 
     def _build_url(self, resource_type, service, parameters={}):
@@ -71,8 +90,56 @@ def _build_url(self, resource_type, service, parameters={}):
     def _discover_services(self):
         """
         Automatically discovers available services.
+
+        They are discovered by downloading the corresponding WADL files. If a
+        WADL does not exist, the services are assumed to be non-existent.
         """
-        self._build_url("dataselect", "application.wadl")
+        dataselect_url = self._build_url("dataselect", "application.wadl")
+        station_url = self._build_url("station", "application.wadl")
+        event_url = self._build_url("event", "application.wadl")
+        urls = (dataselect_url, station_url, event_url)
+
+        # Request all three WADL files in parallel.
+        wadl_queue = Queue.Queue()
+
+        headers = self.request_headers
+        debug = self.debug
+
+        def get_download_thread(url):
+            class ThreadURL(threading.Thread):
+                def run(self):
+                    code, data = download_url(dataselect_url, headers=headers,
+                                              debug=debug)
+                    if code == 200:
+                        wadl_queue.put((url, data))
+                    else:
+                        wadl_queue.put((url, None))
+            return ThreadURL()
+
+        threads = map(get_download_thread, urls)
+        for thread in threads:
+            thread.start()
+        for thread in threads:
+            thread.join(15)
+
+        services = {}
+        for _ in range(wadl_queue.qsize()):
+            item = wadl_queue.get()
+            url, wadl = item
+            if wadl is None:
+                continue
+            if "dataselect" in url:
+                services["dataselect"] = wadl
+                if self.debug is True:
+                    print "Discovered dataselect service"
+            elif "event" in url:
+                services["event"] = wadl
+                if self.debug is True:
+                    print "Discovered event service"
+            elif "station" in url:
+                services["station"] = wadl
+                if self.debug is True:
+                    print "Discovered station service"
 
 
 def build_url(base_url, major_version, resource_type, service, parameters={}):
@@ -102,6 +169,34 @@ def build_url(base_url, major_version, resource_type, service, parameters={}):
     return url
 
 
+def download_url(url, timeout=10, headers={}, debug=False):
+    """
+    Returns a pair of tuples.
+
+    The first one is the returned HTTP code and the second the data as
+    string.
+
+    Will return a touple of Nones if the service could not be found.
+    """
+    if debug is True:
+        print "Downloading %s" % url
+
+    try:
+        url_obj = urllib2.urlopen(urllib2.Request(url=url, headers=headers),
+                                  timeout=timeout)
+    except urllib2.URLError:
+        if debug is True:
+            print "Error while downloading: %s" % url
+        return None, None
+
+    code, data = url_obj.getcode(), url_obj.read()
+
+    if debug is True:
+        print "Downloaded %s with HTTP code: %i" % (url, code)
+
+    return code, data
+
+
 if __name__ == '__main__':
     import doctest
     doctest.testmod(exclude_empty=True)

obspy/fdsn/tests/test_client.py

@@ -43,7 +43,14 @@ def test_url_building(self):
 
         # A wrong resource_type raises a ValueError
         self.assertRaises(ValueError, build_url, "http://service.iris.edu", 1,
-            "obspy", "query")
+                          "obspy", "query")
+
+    def test_service_discovery_iris(self):
+        """
+        Tests the automatic discovery of services with the IRIS endpoint.
+        """
+        c = Client(base_url="IRIS")
+