+ Import from astro.main.sourcecollection.

ExternalTAP/ExternalTAP.py

@@ -9,7 +9,9 @@ from common.log.Error import Error
 import datetime, os
 import urllib
 
-from SourceCollection import SourceCollection
+from astro.main.sourcecollection.SourceCollection import SourceCollection
+from astro.main.sourcecollection.External import External as ExternalBase
+
 from astro.util.SetRelations import SetRelations, SetRelationsSet
 from astro.util.TableConverter import TableConverter
 
@@ -17,7 +19,6 @@ from astro.util.TableConverter import TableConverter
 This file contains the experimental ExternalTAP class, a SourceCollection to
 access IVOA TAP Resources as if they are local SourceCollections.
 
-
 # Below is a workaround to get a fake persistent class.
 # Import it as:
 from astro.main.sourcecollection.ExternalTAP import External as ExternalTAP
@@ -53,7 +54,6 @@ class ExternalTap(SourceCollection):
     
 """
 
-from External import External as ExternalBase
 class External(ExternalBase):
     """
     The experimental ExternalTAP is a SourceCollection to access IVOA TAP
@@ -61,7 +61,9 @@ class External(ExternalBase):
     
     The ExternalTAP points to a IVOA TAP resources from which it can fetch
     data. It has a local sourcelist_data to store this data, which can be
-    shared with SCs further in the tree.
+    shared with SCs further in the tree. This way, an ExternalTAP can represent
+    an entire, possibly very large, TAP resource, while only the rows that are
+    actually required are retrieved.
     
     E.g. An ExternalTAP can point to the PhotoObjAll table of an SDSS resource,
     but not store any catalog data initially. A FilterSources can be created