Update backend.configuration() to use BackendConfiguration (Qiskit#1323)

* update configuration for statevector simulators

* Update configuration() using BackendConfiguration

Update `BaseBackend.configuratio()` in order to use the model object
`BackendConfiguration`, removing a check from the init (as the object
will be schema-conformant) and tweaking docstrings in the process.

* Update default configuration for local simulators

Update the configuration of the rest of local simulators. Original
credit by @ajavadia in Qiskit#1279.

* Updates to simulator configurations, aer

Update the simulator configurations in order:
* remove the `coupling_map` parameter, as it needs to be a list per the
  specs and had the value "all-to-all".
* add the `gates` parameter, as an empty list (that will likely need
  to be populated once it is used anywhere) and it is a required
  parameter per the spec.

Revise the discovery during Aer building, and adjust the checks done
during instantiation to account for the usage of the object, removing
obsolete code (since the object is guaranteed to have some keys such
as backend_name).

* Adjust transpiler access to configuration(), tests

Revise the methods in transpiler that accessed backend configuration,
replacing the indexing by key with property accessing, and the
treatment of basis_gates (str vs list).

Adjust tests.

* Update configuration.gates with one gate

Update `configuration.gates` for the local simulators, as the specs
require them to have at least one element. A temporary gate was added
for the purposes of passing validation, which should be replaced with
the real gates eventually.

* Update IBMQBackend to use BackendConfiguration

Modify `IBMQBackend` in order to use `BackendConfiguration` for its
`.configuration()` method, by:
* moving the processing of the dict returned from the API to the
  `IBMQconnector` layer (cleanup case, add missing fields, handle
  specific fields). This changes has been verified against QX and IBMQ
  current returned values, and hopefully will be temporary until 0.7.
* updating `IBMQProvider` instantiation and discovery (in the provider),
  removing outdated checks.
* update `providerutils` to work with objects instead of dicts.

Adjust tests accordingly, finally enabling the real functionality for
`test_remote_backend_configuration`.

* Fix unitary simulator name during rebasing

* Update CHANGELOG

CHANGELOG.rst

@@ -64,7 +64,10 @@ Changed
 - `IBMQ.save_account()` now takes an `overwrite` option to replace an existing
   account on disk. Default is False (#1295).
 - Backend and Provider methods defined in the specification use model objects
-  rather than dicts, along with validation against schemas (#1249, #1277).
+  rather than dicts, along with validation against schemas (#1249, #1277). The
+  updated methods include:
+    - ``backend.status()``(#1301).
+    - ``backend.configuration()`` (and ``__init__``) (#1323).
 - ``backend.provider()`` is now a method instead of a property (#1312).
 - Remove local backend (Aer) fallback (#1303)
 

qiskit/backends/aer/aerprovider.py

@@ -115,7 +115,7 @@ def _verify_aer_backends(self):
         for backend_cls in AER_STANDARD_BACKENDS:
             try:
                 backend_instance = self._get_backend_instance(backend_cls)
-                backend_name = backend_instance.configuration()['name']
+                backend_name = backend_instance.name()
                 ret[backend_name] = backend_instance
             except QISKitError as err:
                 # Ignore backends that could not be initialized.
@@ -132,8 +132,7 @@ def _get_backend_instance(self, backend_cls):
         Returns:
             BaseBackend: a backend instance.
         Raises:
-            QISKitError: if the backend could not be instantiated or does not
-                provide a valid configuration containing a name.
+            QISKitError: if the backend could not be instantiated.
         """
         # Verify that the backend can be instantiated.
         try:
@@ -142,12 +141,6 @@ def _get_backend_instance(self, backend_cls):
             raise QISKitError('Backend %s could not be instantiated: %s' %
                               (backend_cls, err))
 
-        # Verify that the instance has a minimal valid configuration.
-        try:
-            _ = backend_instance.configuration()['name']
-        except (LookupError, TypeError):
-            raise QISKitError('Backend %s has an invalid configuration')
-
         return backend_instance
 
     def __str__(self):

qiskit/backends/aer/qasm_simulator.py

@@ -20,6 +20,7 @@
 
 import numpy as np
 
+from qiskit.backends.models import BackendConfiguration
 from qiskit.result._utils import copy_qasm_from_qobj_into_result, result_from_old_style_dict
 from qiskit.backends import BaseBackend
 from qiskit.backends.aer.aerjob import AerJob
@@ -46,34 +47,40 @@ class QasmSimulator(BaseBackend):
     """C++ quantum circuit simulator with realistic noise"""
 
     DEFAULT_CONFIGURATION = {
-        'name': 'qasm_simulator',
+        'backend_name': 'qasm_simulator',
+        'backend_version': '1.0.0',
+        'n_qubits': -1,
         'url': 'https://github.com/QISKit/qiskit-terra/src/qasm-simulator-cpp',
         'simulator': True,
         'local': True,
-        'description': 'A C++ realistic noise simulator for qobj files',
-        'coupling_map': 'all-to-all',
-        "basis_gates": 'u0,u1,u2,u3,cx,cz,id,x,y,z,h,s,sdg,t,tdg,rzz,' +
-                       'snapshot,wait,noise,save,load'
+        'conditional': True,
+        'open_pulse': False,
+        'description': 'A C++ realistic noise simulator for qasm experiments',
+        'basis_gates': ['u0', 'u1', 'u2', 'u3', 'cx', 'cz', 'id', 'x', 'y', 'z',
+                        'h', 's', 'sdg', 't', 'tdg', 'rzz', 'snapshot', 'wait',
+                        'noise', 'save', 'load'],
+        'gates': [{'name': 'TODO', 'parameters': [], 'qasm_def': 'TODO'}]
     }
 
     def __init__(self, configuration=None, provider=None):
-        super().__init__(configuration=configuration or self.DEFAULT_CONFIGURATION.copy(),
+        super().__init__(configuration=(configuration or
+                                        BackendConfiguration.from_dict(self.DEFAULT_CONFIGURATION)),
                          provider=provider)
 
         # Try to use the default executable if not specified.
-        if self._configuration.get('exe'):
-            paths = [self._configuration.get('exe')]
+        if 'exe' in self._configuration:
+            paths = [self._configuration.exe]
         else:
             paths = DEFAULT_SIMULATOR_PATHS
 
         # Ensure that the executable is available.
         try:
-            self._configuration['exe'] = next(
+            self._configuration.exe = next(
                 path for path in paths if (os.path.exists(path) and
                                            os.path.getsize(path) > 100))
         except StopIteration:
             raise FileNotFoundError('Simulator executable not found (using %s)' %
-                                    self._configuration.get('exe', 'default locations'))
+                                    getattr(self._configuration, 'exe', 'default locations'))
 
     def run(self, qobj):
         """Run a qobj on the backend."""
@@ -84,7 +91,7 @@ def run(self, qobj):
 
     def _run_job(self, job_id, qobj):
         self._validate(qobj)
-        result = run(qobj, self._configuration['exe'])
+        result = run(qobj, self._configuration.exe)
         result['job_id'] = job_id
         copy_qasm_from_qobj_into_result(qobj, result)
 
@@ -104,33 +111,39 @@ class CliffordSimulator(BaseBackend):
     """"C++ Clifford circuit simulator with realistic noise."""
 
     DEFAULT_CONFIGURATION = {
-        'name': 'clifford_simulator',
-        'url': 'https://github.com/QISKit/qiskit-terra/src/qasm-simulator',
+        'backend_name': 'clifford_simulator',
+        'backend_version': '1.0.0',
+        'n_qubits': -1,
+        'url': 'https://github.com/QISKit/qiskit-terra/src/qasm-simulator-cpp',
         'simulator': True,
         'local': True,
+        'conditional': True,
+        'open_pulse': False,
         'description': 'A C++ Clifford simulator with approximate noise',
-        'coupling_map': 'all-to-all',
-        'basis_gates': 'cx,id,x,y,z,h,s,sdg,snapshot,wait,noise,save,load'
+        'basis_gates': ['cx', 'id', 'x', 'y', 'z', 'h', 's', 'sdg', 'snapshot',
+                        'wait', 'noise', 'save', 'load'],
+        'gates': [{'name': 'TODO', 'parameters': [], 'qasm_def': 'TODO'}]
     }
 
     def __init__(self, configuration=None, provider=None):
-        super().__init__(configuration=configuration or self.DEFAULT_CONFIGURATION.copy(),
+        super().__init__(configuration=(configuration or
+                                        BackendConfiguration.from_dict(self.DEFAULT_CONFIGURATION)),
                          provider=provider)
 
         # Try to use the default executable if not specified.
-        if self._configuration.get('exe'):
-            paths = [self._configuration.get('exe')]
+        if 'exe' in self._configuration:
+            paths = [self._configuration.exe]
         else:
             paths = DEFAULT_SIMULATOR_PATHS
 
         # Ensure that the executable is available.
         try:
-            self._configuration['exe'] = next(
+            self._configuration.exe = next(
                 path for path in paths if (os.path.exists(path) and
                                            os.path.getsize(path) > 100))
         except StopIteration:
             raise FileNotFoundError('Simulator executable not found (using %s)' %
-                                    self._configuration.get('exe', 'default locations'))
+                                    getattr(self._configuration, 'exe', 'default locations'))
 
     def run(self, qobj):
         """Run a Qobj on the backend.
@@ -159,7 +172,7 @@ def _run_job(self, job_id, qobj):
             qobj_dict['config'] = {'simulator': 'clifford'}
 
         qobj = Qobj.from_dict(qobj_dict)
-        result = run(qobj, self._configuration['exe'])
+        result = run(qobj, self._configuration.exe)
         result['job_id'] = job_id
 
         return result_from_old_style_dict(

qiskit/backends/aer/qasm_simulator_py.py

@@ -78,6 +78,7 @@
 
 import numpy as np
 
+from qiskit.backends.models import BackendConfiguration
 from qiskit.result._utils import copy_qasm_from_qobj_into_result, result_from_old_style_dict
 from qiskit.backends import BaseBackend
 from qiskit.backends.aer.aerjob import AerJob
@@ -90,17 +91,22 @@ class QasmSimulatorPy(BaseBackend):
     """Python implementation of a qasm simulator."""
 
     DEFAULT_CONFIGURATION = {
-        'name': 'qasm_simulator_py',
+        'backend_name': 'qasm_simulator_py',
+        'backend_version': '2.0.0',
+        'n_qubits': -1,
         'url': 'https://github.com/QISKit/qiskit-terra',
         'simulator': True,
         'local': True,
-        'description': 'A python simulator for qasm files',
-        'coupling_map': 'all-to-all',
-        'basis_gates': 'u1,u2,u3,cx,id,snapshot'
+        'conditional': True,
+        'open_pulse': False,
+        'description': 'A python simulator for qasm experiments',
+        'basis_gates': ['u1', 'u2', 'u3', 'cx', 'id', 'snapshot'],
+        'gates': [{'name': 'TODO', 'parameters': [], 'qasm_def': 'TODO'}]
     }
 
     def __init__(self, configuration=None, provider=None):
-        super().__init__(configuration=configuration or self.DEFAULT_CONFIGURATION.copy(),
+        super().__init__(configuration=(configuration or
+                                        BackendConfiguration.from_dict(self.DEFAULT_CONFIGURATION)),
                          provider=provider)
 
         self._local_random = random.Random()
@@ -243,7 +249,7 @@ def _run_job(self, job_id, qobj):
         for circuit in qobj.experiments:
             result_list.append(self.run_circuit(circuit))
         end = time.time()
-        result = {'backend': self._configuration['name'],
+        result = {'backend': self.name(),
                   'id': qobj.qobj_id,
                   'job_id': job_id,
                   'result': result_list,
@@ -342,7 +348,7 @@ def run_circuit(self, circuit):
                     params = operation.params
                     self._add_qasm_snapshot(params[0])
                 else:
-                    backend = self._configuration['name']
+                    backend = self.name()
                     err_msg = '{0} encountered unrecognized operation "{1}"'
                     raise SimulatorError(err_msg.format(backend,
                                                         operation.name))

qiskit/backends/aer/statevector_simulator.py

@@ -14,6 +14,7 @@
 import logging
 import uuid
 
+from qiskit.backends.models import BackendConfiguration
 from qiskit.qobj import QobjInstruction
 from .qasm_simulator import QasmSimulator
 from ._simulatorerror import SimulatorError
@@ -26,17 +27,24 @@ class StatevectorSimulator(QasmSimulator):
     """C++ statevector simulator"""
 
     DEFAULT_CONFIGURATION = {
-        'name': 'statevector_simulator',
+        'backend_name': 'statevector_simulator',
+        'backend_version': '1.0.0',
+        'n_qubits': -1,
         'url': 'https://github.com/QISKit/qiskit-terra/src/qasm-simulator-cpp',
         'simulator': True,
         'local': True,
-        'description': 'A C++ statevector simulator for qobj files',
-        'coupling_map': 'all-to-all',
-        'basis_gates': 'u1,u2,u3,cx,cz,id,x,y,z,h,s,sdg,t,tdg,rzz,load,save,snapshot'
+        'conditional': False,
+        'open_pulse': False,
+        'description': 'A single-shot C++ statevector simulator for the |0> state evolution',
+        'basis_gates': ['u1', 'u2', 'u3', 'cx', 'cz', 'id', 'x', 'y', 'z', 'h',
+                        's', 'sdg', 't', 'tdg', 'rzz', 'load', 'save',
+                        'snapshot'],
+        'gates': [{'name': 'TODO', 'parameters': [], 'qasm_def': 'TODO'}]
     }
 
     def __init__(self, configuration=None, provider=None):
-        super().__init__(configuration=configuration or self.DEFAULT_CONFIGURATION.copy(),
+        super().__init__(configuration=(configuration or
+                                        BackendConfiguration.from_dict(self.DEFAULT_CONFIGURATION)),
                          provider=provider)
 
     def run(self, qobj):

qiskit/backends/aer/statevector_simulator_py.py

@@ -23,6 +23,7 @@
 
 from qiskit.backends.aer.aerjob import AerJob
 from qiskit.backends.aer._simulatorerror import SimulatorError
+from qiskit.backends.models import BackendConfiguration
 from qiskit.qobj import QobjInstruction
 from .qasm_simulator_py import QasmSimulatorPy
 
@@ -33,17 +34,22 @@ class StatevectorSimulatorPy(QasmSimulatorPy):
     """Python statevector simulator."""
 
     DEFAULT_CONFIGURATION = {
-        'name': 'statevector_simulator_py',
+        'backend_name': 'statevector_simulator_py',
+        'backend_version': '1.0.0',
+        'n_qubits': -1,
         'url': 'https://github.com/QISKit/qiskit-terra',
         'simulator': True,
         'local': True,
+        'conditional': False,
+        'open_pulse': False,
         'description': 'A Python statevector simulator for qobj files',
-        'coupling_map': 'all-to-all',
-        'basis_gates': 'u1,u2,u3,cx,id,snapshot'
+        'basis_gates': ['u1', 'u2', 'u3', 'cx', 'id', 'snapshot'],
+        'gates': [{'name': 'TODO', 'parameters': [], 'qasm_def': 'TODO'}]
     }
 
     def __init__(self, configuration=None, provider=None):
-        super().__init__(configuration=configuration or self.DEFAULT_CONFIGURATION.copy(),
+        super().__init__(configuration=(configuration or
+                                        BackendConfiguration.from_dict(self.DEFAULT_CONFIGURATION)),
                          provider=provider)
 
     def run(self, qobj):

qiskit/backends/aer/unitary_simulator_py.py

@@ -86,6 +86,7 @@
 
 import numpy as np
 
+from qiskit.backends.models import BackendConfiguration
 from qiskit.result._utils import copy_qasm_from_qobj_into_result, result_from_old_style_dict
 from qiskit.backends import BaseBackend
 from qiskit.backends.aer.aerjob import AerJob
@@ -103,17 +104,22 @@ class UnitarySimulatorPy(BaseBackend):
     """Python implementation of a unitary simulator."""
 
     DEFAULT_CONFIGURATION = {
-        'name': 'unitary_simulator_py',
+        'backend_name': 'unitary_simulator_py',
+        'backend_version': '1.0.0',
+        'n_qubits': -1,
         'url': 'https://github.com/QISKit/qiskit-terra',
         'simulator': True,
         'local': True,
-        'description': 'A python simulator for unitary matrix',
-        'coupling_map': 'all-to-all',
-        'basis_gates': 'u1,u2,u3,cx,id'
+        'conditional': False,
+        'open_pulse': False,
+        'description': 'A python simulator for unitary matrix corresponding to a circuit',
+        'basis_gates': ['u1', 'u2', 'u3', 'cx', 'id'],
+        'gates': [{'name': 'TODO', 'parameters': [], 'qasm_def': 'TODO'}]
     }
 
     def __init__(self, configuration=None, provider=None):
-        super().__init__(configuration=configuration or self.DEFAULT_CONFIGURATION.copy(),
+        super().__init__(configuration=(configuration or
+                                        BackendConfiguration.from_dict(self.DEFAULT_CONFIGURATION)),
                          provider=provider)
 
         # Define attributes inside __init__.
@@ -189,7 +195,7 @@ def _run_job(self, job_id, qobj):
         for circuit in qobj.experiments:
             result_list.append(self.run_circuit(circuit))
         end = time.time()
-        result = {'backend': self._configuration['name'],
+        result = {'backend': self.name(),
                   'id': qobj.qobj_id,
                   'job_id': job_id,
                   'result': result_list,

qiskit/backends/basebackend.py

@@ -28,15 +28,13 @@ def __init__(self, configuration, provider=None):
         not available.
 
         Args:
-            configuration (dict): configuration dictionary
+            configuration (BackendConfiguration): backend configuration
             provider (BaseProvider): provider responsible for this backend
 
         Raises:
             FileNotFoundError if backend executable is not available.
             QISKitError: if there is no name in the configuration
         """
-        if 'name' not in configuration:
-            raise qiskit.QISKitError('backend does not have a name.')
         self._configuration = configuration
         self._provider = provider
 
@@ -46,7 +44,11 @@ def run(self, qobj):
         pass
 
     def configuration(self):
-        """Return backend configuration"""
+        """Return the backend configuration.
+
+        Returns:
+            BackendConfiguration: the configuration fot the backend.
+        """
         return self._configuration
 
     def properties(self):
@@ -57,7 +59,7 @@ def provider(self):
         """Return the backend Provider.
 
         Returns:
-            BaseProvider: the Provider responsible for this backend.
+            BaseProvider: the Provider responsible for the backend.
         """
         return self._provider
 
@@ -74,8 +76,12 @@ def status(self):
                              status_msg='')
 
     def name(self):
-        """Return backend name"""
-        return self._configuration['name']
+        """Return backend name.
+
+        Returns:
+            str: the name of the backend.
+        """
+        return self._configuration.backend_name
 
     def __str__(self):
         return self.name()