gRPC

For documentation, examples, and more, see the Python gRPC page on grpc.io.

Module Contents

Version

The version string is available as grpc.__version__.

Create Client

grpc.insecure_channel(target, options=None, compression=None)

Creates an insecure Channel to a server.

The returned Channel is thread-safe.

Parameters:

• target – The server address

• options – An optional list of key-value pairs (channel_arguments in gRPC Core runtime) to configure the channel.

• compression – An optional value indicating the compression method to be used over the lifetime of the channel.

Returns:

A Channel.

grpc.secure_channel(target, credentials, options=None, compression=None)

Creates a secure Channel to a server.

The returned Channel is thread-safe.

Parameters:

• target – The server address.

• credentials – A ChannelCredentials instance.

• options – An optional list of key-value pairs (channel_arguments in gRPC Core runtime) to configure the channel.

• compression – An optional value indicating the compression method to be used over the lifetime of the channel.

Returns:

A Channel.

grpc.intercept_channel(channel, *interceptors)

Intercepts a channel through a set of interceptors.

Parameters:

• channel – A Channel.

• interceptors – Zero or more objects of type UnaryUnaryClientInterceptor, UnaryStreamClientInterceptor, StreamUnaryClientInterceptor, or StreamStreamClientInterceptor. Interceptors are given control in the order they are listed.

Returns:

A Channel that intercepts each invocation via the provided interceptors.

Raises:

TypeError – If interceptor does not derive from any of UnaryUnaryClientInterceptor, UnaryStreamClientInterceptor, StreamUnaryClientInterceptor, or StreamStreamClientInterceptor.

Create Client Credentials

grpc.ssl_channel_credentials(root_certificates=None, private_key=None, certificate_chain=None)

Creates a ChannelCredentials for use with an SSL-enabled Channel.

Parameters:

• root_certificates – The PEM-encoded root certificates as a byte string, or None to retrieve them from a default location chosen by gRPC runtime.

• private_key – The PEM-encoded private key as a byte string, or None if no private key should be used.

• certificate_chain – The PEM-encoded certificate chain as a byte string to use or None if no certificate chain should be used.

Returns:

A ChannelCredentials for use with an SSL-enabled Channel.

grpc.metadata_call_credentials(metadata_plugin, name=None)

Construct CallCredentials from an AuthMetadataPlugin.

Parameters:

• metadata_plugin – An AuthMetadataPlugin to use for authentication.

• name – An optional name for the plugin.

Returns:

A CallCredentials.

grpc.access_token_call_credentials(access_token)

Construct CallCredentials from an access token.

Parameters:

access_token – A string to place directly in the http request authorization header, for example “authorization: Bearer <access_token>”.

Returns:

A CallCredentials.

grpc.composite_call_credentials(*call_credentials)

Compose multiple CallCredentials to make a new CallCredentials.

Parameters:

*call_credentials – At least two CallCredentials objects.

Returns:

A CallCredentials object composed of the given CallCredentials objects.

grpc.composite_channel_credentials(channel_credentials, *call_credentials)

Compose a ChannelCredentials and one or more CallCredentials objects.

Parameters:

• channel_credentials – A ChannelCredentials object.

• *call_credentials – One or more CallCredentials objects.

Returns:

A ChannelCredentials composed of the given ChannelCredentials and

CallCredentials objects.

grpc.local_channel_credentials(local_connect_type=grpc.LocalConnectionType.LOCAL_TCP)

Creates a local ChannelCredentials used for local connections.

This is an EXPERIMENTAL API.

Local credentials are used by local TCP endpoints (e.g. localhost:10000) also UDS connections.

The connections created by local channel credentials are not encrypted, but will be checked if they are local or not. The UDS connections are considered secure by providing peer authentication and data confidentiality while TCP connections are considered insecure.

It is allowed to transmit call credentials over connections created by local channel credentials.

Local channel credentials are useful for 1) eliminating insecure_channel usage; 2) enable unit testing for call credentials without setting up secrets.

Parameters:

local_connect_type – Local connection type (either grpc.LocalConnectionType.UDS or grpc.LocalConnectionType.LOCAL_TCP)

Returns:

A ChannelCredentials for use with a local Channel

grpc.compute_engine_channel_credentials(call_credentials)

Creates a compute engine channel credential.

This credential can only be used in a GCP environment as it relies on a handshaker service. For more info about ALTS, see https://cloud.google.com/security/encryption-in-transit/application-layer-transport-security

This channel credential is expected to be used as part of a composite credential in conjunction with a call credentials that authenticates the VM’s default service account. If used with any other sort of call credential, the connection may suddenly and unexpectedly begin failing RPCs.

Create Server

grpc.server(thread_pool, handlers=None, interceptors=None, options=None, maximum_concurrent_rpcs=None, compression=None, xds=False)

Creates a Server with which RPCs can be serviced.

Parameters:

• thread_pool – A futures.ThreadPoolExecutor to be used by the Server to execute RPC handlers.

• handlers – An optional list of GenericRpcHandlers used for executing RPCs. More handlers may be added by calling add_generic_rpc_handlers any time before the server is started.

• interceptors – An optional list of ServerInterceptor objects that observe and optionally manipulate the incoming RPCs before handing them over to handlers. The interceptors are given control in the order they are specified. This is an EXPERIMENTAL API.

• options – An optional list of key-value pairs (channel_arguments in gRPC runtime) to configure the channel.

• maximum_concurrent_rpcs – The maximum number of concurrent RPCs this server will service before returning RESOURCE_EXHAUSTED status, or None to indicate no limit.

• compression – An element of grpc.compression, e.g. grpc.compression.Gzip. This compression algorithm will be used for the lifetime of the server unless overridden.

• xds – If set to true, retrieves server configuration via xDS. This is an EXPERIMENTAL option.

Returns:

A Server object.

Create Server Credentials

grpc.ssl_server_credentials(private_key_certificate_chain_pairs, root_certificates=None, require_client_auth=False)

Creates a ServerCredentials for use with an SSL-enabled Server.

Parameters:

• private_key_certificate_chain_pairs – A list of pairs of the form [PEM-encoded private key, PEM-encoded certificate chain].

• root_certificates – An optional byte string of PEM-encoded client root certificates that the server will use to verify client authentication. If omitted, require_client_auth must also be False.

• require_client_auth – A boolean indicating whether or not to require clients to be authenticated. May only be True if root_certificates is not None.

Returns:

A ServerCredentials for use with an SSL-enabled Server. Typically, this object is an argument to add_secure_port() method during server setup.

grpc.ssl_server_certificate_configuration(private_key_certificate_chain_pairs, root_certificates=None)

Creates a ServerCertificateConfiguration for use with a Server.

Parameters:

• private_key_certificate_chain_pairs – A collection of pairs of the form [PEM-encoded private key, PEM-encoded certificate chain].

• root_certificates – An optional byte string of PEM-encoded client root certificates that the server will use to verify client authentication.

Returns:

A ServerCertificateConfiguration that can be returned in the certificate

configuration fetching callback.

grpc.dynamic_ssl_server_credentials(initial_certificate_configuration, certificate_configuration_fetcher, require_client_authentication=False)

Creates a ServerCredentials for use with an SSL-enabled Server.

Parameters:

• initial_certificate_configuration (ServerCertificateConfiguration) – The certificate configuration with which the server will be initialized.

• certificate_configuration_fetcher (callable) – A callable that takes no arguments and should return a ServerCertificateConfiguration to replace the server’s current certificate, or None for no change (i.e., the server will continue its current certificate config). The library will call this callback on every new client connection before starting the TLS handshake with the client, thus allowing the user application to optionally return a new ServerCertificateConfiguration that the server will then use for the handshake.

• require_client_authentication – A boolean indicating whether or not to require clients to be authenticated.

Returns:

A ServerCredentials.

grpc.local_server_credentials(local_connect_type=grpc.LocalConnectionType.LOCAL_TCP)

Creates a local ServerCredentials used for local connections.

This is an EXPERIMENTAL API.

Local credentials are used by local TCP endpoints (e.g. localhost:10000) also UDS connections.

The connections created by local server credentials are not encrypted, but will be checked if they are local or not. The UDS connections are considered secure by providing peer authentication and data confidentiality while TCP connections are considered insecure.

It is allowed to transmit call credentials over connections created by local server credentials.

Local server credentials are useful for 1) eliminating insecure_channel usage; 2) enable unit testing for call credentials without setting up secrets.

Parameters:

local_connect_type – Local connection type (either grpc.LocalConnectionType.UDS or grpc.LocalConnectionType.LOCAL_TCP)

Returns:

A ServerCredentials for use with a local Server

Local Connection Type

class grpc.LocalConnectionType(value)

Types of local connection for local credential creation.

UDS

Unix domain socket connections

LOCAL_TCP

Local TCP connections.

RPC Method Handlers

grpc.unary_unary_rpc_method_handler(behavior, request_deserializer=None, response_serializer=None)

Creates an RpcMethodHandler for a unary-unary RPC method.

Parameters:

• behavior – The implementation of an RPC that accepts one request and returns one response.

• request_deserializer – An optional deserializer for request deserialization.

• response_serializer – An optional serializer for response serialization.

Returns:

An RpcMethodHandler object that is typically used by grpc.Server.

grpc.unary_stream_rpc_method_handler(behavior, request_deserializer=None, response_serializer=None)

Creates an RpcMethodHandler for a unary-stream RPC method.

Parameters:

• behavior – The implementation of an RPC that accepts one request and returns an iterator of response values.

• request_deserializer – An optional deserializer for request deserialization.

• response_serializer – An optional serializer for response serialization.

Returns:

An RpcMethodHandler object that is typically used by grpc.Server.

grpc.stream_unary_rpc_method_handler(behavior, request_deserializer=None, response_serializer=None)

Creates an RpcMethodHandler for a stream-unary RPC method.

Parameters:

• behavior – The implementation of an RPC that accepts an iterator of request values and returns a single response value.

• request_deserializer – An optional deserializer for request deserialization.

• response_serializer – An optional serializer for response serialization.

Returns:

An RpcMethodHandler object that is typically used by grpc.Server.

grpc.stream_stream_rpc_method_handler(behavior, request_deserializer=None, response_serializer=None)

Creates an RpcMethodHandler for a stream-stream RPC method.

Parameters:

• behavior – The implementation of an RPC that accepts an iterator of request values and returns an iterator of response values.

• request_deserializer – An optional deserializer for request deserialization.

• response_serializer – An optional serializer for response serialization.

Returns:

An RpcMethodHandler object that is typically used by grpc.Server.

grpc.method_handlers_generic_handler(service, method_handlers)

Creates a GenericRpcHandler from RpcMethodHandlers.

Parameters:

• service – The name of the service that is implemented by the method_handlers.

• method_handlers – A dictionary that maps method names to corresponding RpcMethodHandler.

Returns:

A GenericRpcHandler. This is typically added to the grpc.Server object with add_generic_rpc_handlers() before starting the server.

Channel Ready Future

grpc.channel_ready_future(channel)

Creates a Future that tracks when a Channel is ready.

Cancelling the Future does not affect the channel’s state machine. It merely decouples the Future from channel state machine.

Parameters:

channel – A Channel object.

Returns:

A Future object that matures when the channel connectivity is ChannelConnectivity.READY.

Channel Connectivity

class grpc.ChannelConnectivity(value)

Mirrors grpc_connectivity_state in the gRPC Core.

IDLE

The channel is idle.

CONNECTING

The channel is connecting.

READY

The channel is ready to conduct RPCs.

TRANSIENT_FAILURE

The channel has seen a failure from which it expects to recover.

SHUTDOWN

The channel has seen a failure from which it cannot recover.

gRPC Status Code

class grpc.StatusCode(value)

Mirrors grpc_status_code in the gRPC Core.

OK

Not an error; returned on success

CANCELLED

The operation was cancelled (typically by the caller).

UNKNOWN

Unknown error.

INVALID_ARGUMENT

Client specified an invalid argument.

DEADLINE_EXCEEDED

Deadline expired before operation could complete.

NOT_FOUND

Some requested entity (e.g., file or directory) was not found.

ALREADY_EXISTS

Some entity that we attempted to create (e.g., file or directory) already exists.

PERMISSION_DENIED

The caller does not have permission to execute the specified operation.

UNAUTHENTICATED

The request does not have valid authentication credentials for the operation.

RESOURCE_EXHAUSTED

Some resource has been exhausted, perhaps a per-user quota, or perhaps the entire file system is out of space.

FAILED_PRECONDITION

Operation was rejected because the system is not in a state required for the operation’s execution.

ABORTED

The operation was aborted, typically due to a concurrency issue like sequencer check failures, transaction aborts, etc.

UNIMPLEMENTED

Operation is not implemented or not supported/enabled in this service.

INTERNAL

Internal errors. Means some invariants expected by underlying system has been broken.

UNAVAILABLE

The service is currently unavailable.

DATA_LOSS

Unrecoverable data loss or corruption.

Channel Object

class grpc.Channel

Affords RPC invocation via generic methods on client-side.

Channel objects implement the Context Manager type, although they need not support being entered and exited multiple times.

__enter__()

Enters the runtime context related to the channel object.

__exit__(exc_type, exc_val, exc_tb)

Exits the runtime context related to the channel object.

abstract close()

Closes this Channel and releases all resources held by it.

Closing the Channel will immediately terminate all RPCs active with the Channel and it is not valid to invoke new RPCs with the Channel.

This method is idempotent.

abstract stream_stream(method, request_serializer=None, response_deserializer=None, _registered_method=False)

Creates a StreamStreamMultiCallable for a stream-stream method.

Parameters:

• method – The name of the RPC method.

• request_serializer – Optional serializer for serializing the request message. Request goes unserialized in case None is passed.

• response_deserializer – Optional deserializer for deserializing the response message. Response goes undeserialized in case None is passed.

• _registered_method – Implementation Private. A bool representing whether the method is registered.

Returns:

A StreamStreamMultiCallable value for the named stream-stream method.

abstract stream_unary(method, request_serializer=None, response_deserializer=None, _registered_method=False)

Creates a StreamUnaryMultiCallable for a stream-unary method.

Parameters:

• method – The name of the RPC method.

• request_serializer – Optional serializer for serializing the request message. Request goes unserialized in case None is passed.

• response_deserializer – Optional deserializer for deserializing the response message. Response goes undeserialized in case None is passed.

• _registered_method – Implementation Private. A bool representing whether the method is registered.

Returns:

A StreamUnaryMultiCallable value for the named stream-unary method.

abstract subscribe(callback, try_to_connect=False)

Subscribe to this Channel’s connectivity state machine.

A Channel may be in any of the states described by ChannelConnectivity. This method allows application to monitor the state transitions. The typical use case is to debug or gain better visibility into gRPC runtime’s state.

Parameters:

• callback – A callable to be invoked with ChannelConnectivity argument. ChannelConnectivity describes current state of the channel. The callable will be invoked immediately upon subscription and again for every change to ChannelConnectivity until it is unsubscribed or this Channel object goes out of scope.

• try_to_connect – A boolean indicating whether or not this Channel should attempt to connect immediately. If set to False, gRPC runtime decides when to connect.

abstract unary_stream(method, request_serializer=None, response_deserializer=None, _registered_method=False)

Creates a UnaryStreamMultiCallable for a unary-stream method.

Parameters:

• method – The name of the RPC method.

• request_serializer – Optional serializer for serializing the request message. Request goes unserialized in case None is passed.

• response_deserializer – Optional deserializer for deserializing the response message. Response goes undeserialized in case None is passed.

• _registered_method – Implementation Private. A bool representing whether the method is registered.

Returns:

A UnaryStreamMultiCallable value for the name unary-stream method.

abstract unary_unary(method, request_serializer=None, response_deserializer=None, _registered_method=False)

Creates a UnaryUnaryMultiCallable for a unary-unary method.

Parameters:

• method – The name of the RPC method.

• request_serializer – Optional serializer for serializing the request message. Request goes unserialized in case None is passed.

• response_deserializer – Optional deserializer for deserializing the response message. Response goes undeserialized in case None is passed.

• _registered_method – Implementation Private. A bool representing whether the method is registered.

Returns:

A UnaryUnaryMultiCallable value for the named unary-unary method.

abstract unsubscribe(callback)

Unsubscribes a subscribed callback from this Channel’s connectivity.

Parameters:

• callback – A callable previously registered with this Channel from

• method. (having been passed to its "subscribe") –

Server Object

class grpc.Server

Services RPCs.

abstract add_generic_rpc_handlers(generic_rpc_handlers)

Registers GenericRpcHandlers with this Server.

This method is only safe to call before the server is started.

Parameters:

• generic_rpc_handlers – An iterable of GenericRpcHandlers that will be

• RPCs. (used to service) –

abstract add_insecure_port(address)

Opens an insecure port for accepting RPCs.

This method may only be called before starting the server.

Parameters:

address – The address for which to open a port. If the port is 0, or not specified in the address, then gRPC runtime will choose a port.

Returns:

An integer port on which server will accept RPC requests.

add_registered_method_handlers(service_name, method_handlers)

Registers GenericRpcHandlers with this Server.

This method is only safe to call before the server is started.

If the same method have both generic and registered handler, registered handler will take precedence.

Parameters:

• service_name – The service name.

• method_handlers – A dictionary that maps method names to corresponding RpcMethodHandler.

abstract add_secure_port(address, server_credentials)

Opens a secure port for accepting RPCs.

This method may only be called before starting the server.

Parameters:

• address – The address for which to open a port. if the port is 0, or not specified in the address, then gRPC runtime will choose a port.

• server_credentials – A ServerCredentials object.

Returns:

An integer port on which server will accept RPC requests.

abstract start()

Starts this Server.

This method may only be called once. (i.e. it is not idempotent).

abstract stop(grace)

Stops this Server.

This method immediately stop service of new RPCs in all cases.

If a grace period is specified, this method waits until all active RPCs are finished or until the grace period is reached. RPCs that haven’t been terminated within the grace period are aborted. If a grace period is not specified (by passing None for grace), all existing RPCs are aborted immediately and this method blocks until the last RPC handler terminates.

This method is idempotent and may be called at any time. Passing a smaller grace value in a subsequent call will have the effect of stopping the Server sooner (passing None will have the effect of stopping the server immediately). Passing a larger grace value in a subsequent call will not have the effect of stopping the server later (i.e. the most restrictive grace value is used).

Parameters:

grace – A duration of time in seconds or None.

Returns:

A threading.Event that will be set when this Server has completely stopped, i.e. when running RPCs either complete or are aborted and all handlers have terminated.

wait_for_termination(timeout=None)

Block current thread until the server stops.

This is an EXPERIMENTAL API.

The wait will not consume computational resources during blocking, and it will block until one of the two following conditions are met:

1. The server is stopped or terminated;

2. A timeout occurs if timeout is not None.

The timeout argument works in the same way as threading.Event.wait(). https://docs.python.org/3/library/threading.html#threading.Event.wait

Parameters:

timeout – A floating point number specifying a timeout for the operation in seconds.

Returns:

A bool indicates if the operation times out.

Authentication & Authorization Objects

class grpc.ChannelCredentials(credentials)

An encapsulation of the data required to create a secure Channel.

This class has no supported interface - it exists to define the type of its instances and its instances exist to be passed to other functions. For example, ssl_channel_credentials returns an instance of this class and secure_channel requires an instance of this class.

class grpc.CallCredentials(credentials)

An encapsulation of the data required to assert an identity over a call.

A CallCredentials has to be used with secure Channel, otherwise the metadata will not be transmitted to the server.

A CallCredentials may be composed with ChannelCredentials to always assert identity for every call over that Channel.

This class has no supported interface - it exists to define the type of its instances and its instances exist to be passed to other functions.

class grpc.AuthMetadataContext

Provides information to call credentials metadata plugins.

service_url

A string URL of the service being called into.

method_name

A string of the fully qualified method name being called.

class grpc.AuthMetadataPluginCallback

Callback object received by a metadata plugin.

__call__(metadata, error)

Passes to the gRPC runtime authentication metadata for an RPC.

Parameters:

• metadata – The metadata used to construct the CallCredentials.

• error – An Exception to indicate error or None to indicate success.

class grpc.AuthMetadataPlugin

A specification for custom authentication.

__call__(context, callback)

Implements authentication by passing metadata to a callback.

This method will be invoked asynchronously in a separate thread.

Parameters:

• context – An AuthMetadataContext providing information on the RPC that the plugin is being called to authenticate.

• callback – An AuthMetadataPluginCallback to be invoked either synchronously or asynchronously.

class grpc.ServerCredentials(credentials)

An encapsulation of the data required to open a secure port on a Server.

This class has no supported interface - it exists to define the type of its instances and its instances exist to be passed to other functions.

class grpc.ServerCertificateConfiguration(certificate_configuration)

A certificate configuration for use with an SSL-enabled Server.

Instances of this class can be returned in the certificate configuration fetching callback.

This class has no supported interface – it exists to define the type of its instances and its instances exist to be passed to other functions.

gRPC Exceptions

exception grpc.RpcError

Raised by the gRPC library to indicate non-OK-status RPC termination.

RPC Context

class grpc.RpcContext

Provides RPC-related information and action.

abstract add_callback(callback)

Registers a callback to be called on RPC termination.

Parameters:

callback – A no-parameter callable to be called on RPC termination.

Returns:

True if the callback was added and will be called later; False if

the callback was not added and will not be called (because the RPC already terminated or some other reason).

abstract cancel()

Cancels the RPC.

Idempotent and has no effect if the RPC has already terminated.

abstract is_active()

Describes whether the RPC is active or has terminated.

Returns:

True if RPC is active, False otherwise.

Return type:

bool

abstract time_remaining()

Describes the length of allowed time remaining for the RPC.

Returns:

A nonnegative float indicating the length of allowed time in seconds remaining for the RPC to complete before it is considered to have timed out, or None if no deadline was specified for the RPC.

Client-Side Context

class grpc.Call

Invocation-side utility object for an RPC.

abstract code()

Accesses the status code sent by the server.

This method blocks until the value is available.

Returns:

The StatusCode value for the RPC.

abstract details()

Accesses the details sent by the server.

This method blocks until the value is available.

Returns:

The details string of the RPC.

abstract initial_metadata()

Accesses the initial metadata sent by the server.

This method blocks until the value is available.

Returns:

The initial metadata.

abstract trailing_metadata()

Accesses the trailing metadata sent by the server.

This method blocks until the value is available.

Returns:

The trailing metadata.

Client-Side Interceptor

class grpc.ClientCallDetails

Describes an RPC to be invoked.

method

The method name of the RPC.

timeout

An optional duration of time in seconds to allow for the RPC.

metadata

Optional metadata to be transmitted to the service-side of the RPC.

credentials

An optional CallCredentials for the RPC.

wait_for_ready

An optional flag to enable wait_for_ready mechanism.

compression

An element of grpc.compression, e.g. grpc.compression.Gzip.

class grpc.UnaryUnaryClientInterceptor

Affords intercepting unary-unary invocations.

abstract intercept_unary_unary(continuation, client_call_details, request)

Intercepts a unary-unary invocation asynchronously.

Parameters:

• continuation – A function that proceeds with the invocation by executing the next interceptor in chain or invoking the actual RPC on the underlying Channel. It is the interceptor’s responsibility to call it if it decides to move the RPC forward. The interceptor can use response_future = continuation(client_call_details, request) to continue with the RPC. continuation returns an object that is both a Call for the RPC and a Future. In the event of RPC completion, the return Call-Future’s result value will be the response message of the RPC. Should the event terminate with non-OK status, the returned Call-Future’s exception value will be an RpcError.

• client_call_details – A ClientCallDetails object describing the outgoing RPC.

• request – The request value for the RPC.

Returns:

An object that is both a Call for the RPC and a Future. In the event of RPC completion, the return Call-Future’s result value will be the response message of the RPC. Should the event terminate with non-OK status, the returned Call-Future’s exception value will be an RpcError.

class grpc.UnaryStreamClientInterceptor

Affords intercepting unary-stream invocations.

abstract intercept_unary_stream(continuation, client_call_details, request)

Intercepts a unary-stream invocation.

Parameters:

• continuation – A function that proceeds with the invocation by executing the next interceptor in chain or invoking the actual RPC on the underlying Channel. It is the interceptor’s responsibility to call it if it decides to move the RPC forward. The interceptor can use response_iterator = continuation(client_call_details, request) to continue with the RPC. continuation returns an object that is both a Call for the RPC and an iterator for response values. Drawing response values from the returned Call-iterator may raise RpcError indicating termination of the RPC with non-OK status.

• client_call_details – A ClientCallDetails object describing the outgoing RPC.

• request – The request value for the RPC.

Returns:

An object that is both a Call for the RPC and an iterator of response values. Drawing response values from the returned Call-iterator may raise RpcError indicating termination of the RPC with non-OK status. This object should also fulfill the Future interface, though it may not.

class grpc.StreamUnaryClientInterceptor

Affords intercepting stream-unary invocations.

abstract intercept_stream_unary(continuation, client_call_details, request_iterator)

Intercepts a stream-unary invocation asynchronously.

Parameters:

• continuation – A function that proceeds with the invocation by executing the next interceptor in chain or invoking the actual RPC on the underlying Channel. It is the interceptor’s responsibility to call it if it decides to move the RPC forward. The interceptor can use response_future = continuation(client_call_details, request_iterator) to continue with the RPC. continuation returns an object that is both a Call for the RPC and a Future. In the event of RPC completion, the return Call-Future’s result value will be the response message of the RPC. Should the event terminate with non-OK status, the returned Call-Future’s exception value will be an RpcError.

• client_call_details – A ClientCallDetails object describing the outgoing RPC.

• request_iterator – An iterator that yields request values for the RPC.

Returns:

An object that is both a Call for the RPC and a Future. In the event of RPC completion, the return Call-Future’s result value will be the response message of the RPC. Should the event terminate with non-OK status, the returned Call-Future’s exception value will be an RpcError.

class grpc.StreamStreamClientInterceptor

Affords intercepting stream-stream invocations.

abstract intercept_stream_stream(continuation, client_call_details, request_iterator)

Intercepts a stream-stream invocation.

Parameters:

• continuation – A function that proceeds with the invocation by executing the next interceptor in chain or invoking the actual RPC on the underlying Channel. It is the interceptor’s responsibility to call it if it decides to move the RPC forward. The interceptor can use response_iterator = continuation(client_call_details, request_iterator) to continue with the RPC. continuation returns an object that is both a Call for the RPC and an iterator for response values. Drawing response values from the returned Call-iterator may raise RpcError indicating termination of the RPC with non-OK status.

• client_call_details – A ClientCallDetails object describing the outgoing RPC.

• request_iterator – An iterator that yields request values for the RPC.

Returns:

An object that is both a Call for the RPC and an iterator of response values. Drawing response values from the returned Call-iterator may raise RpcError indicating termination of the RPC with non-OK status. This object should also fulfill the Future interface, though it may not.

Service-Side Context

class grpc.ServicerContext

A context object passed to method implementations.

abstract abort(code, details)

Raises an exception to terminate the RPC with a non-OK status.

The code and details passed as arguments will supercede any existing ones.

Parameters:

• code – A StatusCode object to be sent to the client. It must not be StatusCode.OK.

• details – A UTF-8-encodable string to be sent to the client upon termination of the RPC.

Raises:

Exception – An exception is always raised to signal the abortion the RPC to the gRPC runtime.

abstract abort_with_status(status)

Raises an exception to terminate the RPC with a non-OK status.

The status passed as argument will supercede any existing status code, status message and trailing metadata.

This is an EXPERIMENTAL API.

Parameters:

status – A grpc.Status object. The status code in it must not be StatusCode.OK.

Raises:

Exception – An exception is always raised to signal the abortion the RPC to the gRPC runtime.

abstract auth_context()

Gets the auth context for the call.

Returns:

A map of strings to an iterable of bytes for each auth property.

code()

Accesses the value to be used as status code upon RPC completion.

This is an EXPERIMENTAL API.

Returns:

The StatusCode value for the RPC.

details()

Accesses the value to be used as detail string upon RPC completion.

This is an EXPERIMENTAL API.

Returns:

The details string of the RPC.

disable_next_message_compression()

Disables compression for the next response message.

This method will override any compression configuration set during server creation or set on the call.

abstract invocation_metadata()

Accesses the metadata sent by the client.

Returns:

The invocation metadata.

abstract peer()

Identifies the peer that invoked the RPC being serviced.

Returns:

A string identifying the peer that invoked the RPC being serviced. The string format is determined by gRPC runtime.

abstract peer_identities()

Gets one or more peer identity(s).

Equivalent to servicer_context.auth_context().get(servicer_context.peer_identity_key())

Returns:

An iterable of the identities, or None if the call is not authenticated. Each identity is returned as a raw bytes type.

abstract peer_identity_key()

The auth property used to identify the peer.

For example, “x509_common_name” or “x509_subject_alternative_name” are used to identify an SSL peer.

Returns:

The auth property (string) that indicates the peer identity, or None if the call is not authenticated.

abstract send_initial_metadata(initial_metadata)

Sends the initial metadata value to the client.

This method need not be called by implementations if they have no metadata to add to what the gRPC runtime will transmit.

Parameters:

initial_metadata – The initial metadata.

abstract set_code(code)

Sets the value to be used as status code upon RPC completion.

This method need not be called by method implementations if they wish the gRPC runtime to determine the status code of the RPC.

Parameters:

code – A StatusCode object to be sent to the client.

set_compression(compression)

Set the compression algorithm to be used for the entire call.

Parameters:

compression – An element of grpc.compression, e.g. grpc.compression.Gzip.

abstract set_details(details)

Sets the value to be used as detail string upon RPC completion.

This method need not be called by method implementations if they have no details to transmit.

Parameters:

details – A UTF-8-encodable string to be sent to the client upon termination of the RPC.

abstract set_trailing_metadata(trailing_metadata)

Sets the trailing metadata for the RPC.

Sets the trailing metadata to be sent upon completion of the RPC.

If this method is invoked multiple times throughout the lifetime of an RPC, the value supplied in the final invocation will be the value sent over the wire.

This method need not be called by implementations if they have no metadata to add to what the gRPC runtime will transmit.

Parameters:

trailing_metadata – The trailing metadata.

trailing_metadata()

Access value to be used as trailing metadata upon RPC completion.

This is an EXPERIMENTAL API.

Returns:

The trailing metadata for the RPC.

Service-Side Handler

class grpc.RpcMethodHandler

An implementation of a single RPC method.

request_streaming

Whether the RPC supports exactly one request message or any arbitrary number of request messages.

response_streaming

Whether the RPC supports exactly one response message or any arbitrary number of response messages.

request_deserializer

A callable deserializer that accepts a byte string and returns an object suitable to be passed to this object’s business logic, or None to indicate that this object’s business logic should be passed the raw request bytes.

response_serializer

A callable serializer that accepts an object produced by this object’s business logic and returns a byte string, or None to indicate that the byte strings produced by this object’s business logic should be transmitted on the wire as they are.

unary_unary

This object’s application-specific business logic as a callable value that takes a request value and a ServicerContext object and returns a response value. Only non-None if both request_streaming and response_streaming are False.

unary_stream

This object’s application-specific business logic as a callable value that takes a request value and a ServicerContext object and returns an iterator of response values. Only non-None if request_streaming is False and response_streaming is True.

stream_unary

This object’s application-specific business logic as a callable value that takes an iterator of request values and a ServicerContext object and returns a response value. Only non-None if request_streaming is True and response_streaming is False.

stream_stream

This object’s application-specific business logic as a callable value that takes an iterator of request values and a ServicerContext object and returns an iterator of response values. Only non-None if request_streaming and response_streaming are both True.

class grpc.HandlerCallDetails

Describes an RPC that has just arrived for service.

method

The method name of the RPC.

invocation_metadata

The metadata sent by the client.

class grpc.GenericRpcHandler

An implementation of arbitrarily many RPC methods.

abstract service(handler_call_details)

Returns the handler for servicing the RPC.

Parameters:

handler_call_details – A HandlerCallDetails describing the RPC.

Returns:

An RpcMethodHandler with which the RPC may be serviced if the implementation chooses to service this RPC, or None otherwise.

class grpc.ServiceRpcHandler

An implementation of RPC methods belonging to a service.

A service handles RPC methods with structured names of the form ‘/Service.Name/Service.Method’, where ‘Service.Name’ is the value returned by service_name(), and ‘Service.Method’ is the method name. A service can have multiple method names, but only a single service name.

abstract service_name()

Returns this service’s name.

Returns:

The service name.

Service-Side Interceptor

class grpc.ServerInterceptor

Affords intercepting incoming RPCs on the service-side.

abstract intercept_service(continuation, handler_call_details)

Intercepts incoming RPCs before handing them over to a handler.

State can be passed from an interceptor to downstream interceptors via contextvars. The first interceptor is called from an empty contextvars.Context, and the same Context is used for downstream interceptors and for the final handler call. Note that there are no guarantees that interceptors and handlers will be called from the same thread.

Parameters:

• continuation – A function that takes a HandlerCallDetails and proceeds to invoke the next interceptor in the chain, if any, or the RPC handler lookup logic, with the call details passed as an argument, and returns an RpcMethodHandler instance if the RPC is considered serviced, or None otherwise.

• handler_call_details – A HandlerCallDetails describing the RPC.

Returns:

An RpcMethodHandler with which the RPC may be serviced if the interceptor chooses to service this RPC, or None otherwise.

Multi-Callable Interfaces

class grpc.UnaryUnaryMultiCallable

Affords invoking a unary-unary RPC from client-side.

abstract __call__(request, timeout=None, metadata=None, credentials=None, wait_for_ready=None, compression=None)

Synchronously invokes the underlying RPC.

Parameters:

• request – The request value for the RPC.

• timeout – An optional duration of time in seconds to allow for the RPC.

• metadata – Optional metadata to be transmitted to the service-side of the RPC.

• credentials – An optional CallCredentials for the RPC. Only valid for secure Channel.

• wait_for_ready – An optional flag to enable wait_for_ready mechanism.

• compression – An element of grpc.compression, e.g. grpc.compression.Gzip.

Returns:

The response value for the RPC.

Raises:

RpcError – Indicating that the RPC terminated with non-OK status. The raised RpcError will also be a Call for the RPC affording the RPC’s metadata, status code, and details.

abstract future(request, timeout=None, metadata=None, credentials=None, wait_for_ready=None, compression=None)

Asynchronously invokes the underlying RPC.

Parameters:

• request – The request value for the RPC.

• timeout – An optional duration of time in seconds to allow for the RPC.

• metadata – Optional metadata to be transmitted to the service-side of the RPC.

• credentials – An optional CallCredentials for the RPC. Only valid for secure Channel.

• wait_for_ready – An optional flag to enable wait_for_ready mechanism.

• compression – An element of grpc.compression, e.g. grpc.compression.Gzip.

Returns:

An object that is both a Call for the RPC and a Future. In the event of RPC completion, the return Call-Future’s result value will be the response message of the RPC. Should the event terminate with non-OK status, the returned Call-Future’s exception value will be an RpcError.

abstract with_call(request, timeout=None, metadata=None, credentials=None, wait_for_ready=None, compression=None)

Synchronously invokes the underlying RPC.

Parameters:

• request – The request value for the RPC.

• timeout – An optional durating of time in seconds to allow for the RPC.

• metadata – Optional metadata to be transmitted to the service-side of the RPC.

• credentials – An optional CallCredentials for the RPC. Only valid for secure Channel.

• wait_for_ready – An optional flag to enable wait_for_ready mechanism.

• compression – An element of grpc.compression, e.g. grpc.compression.Gzip.

Returns:

The response value for the RPC and a Call value for the RPC.

Raises:

RpcError – Indicating that the RPC terminated with non-OK status. The raised RpcError will also be a Call for the RPC affording the RPC’s metadata, status code, and details.

class grpc.UnaryStreamMultiCallable

Affords invoking a unary-stream RPC from client-side.

abstract __call__(request, timeout=None, metadata=None, credentials=None, wait_for_ready=None, compression=None)

Invokes the underlying RPC.

Parameters:

• request – The request value for the RPC.

• timeout – An optional duration of time in seconds to allow for the RPC. If None, the timeout is considered infinite.

• metadata – An optional metadata to be transmitted to the service-side of the RPC.

• credentials – An optional CallCredentials for the RPC. Only valid for secure Channel.

• wait_for_ready – An optional flag to enable wait_for_ready mechanism.

• compression – An element of grpc.compression, e.g. grpc.compression.Gzip.

Returns:

An object that is a Call for the RPC, an iterator of response values, and a Future for the RPC. Drawing response values from the returned Call-iterator may raise RpcError indicating termination of the RPC with non-OK status.

class grpc.StreamUnaryMultiCallable

Affords invoking a stream-unary RPC from client-side.

abstract __call__(request_iterator, timeout=None, metadata=None, credentials=None, wait_for_ready=None, compression=None)

Synchronously invokes the underlying RPC.

Parameters:

• request_iterator – An iterator that yields request values for the RPC.

• timeout – An optional duration of time in seconds to allow for the RPC. If None, the timeout is considered infinite.

• metadata – Optional metadata to be transmitted to the service-side of the RPC.

• credentials – An optional CallCredentials for the RPC. Only valid for secure Channel.

• wait_for_ready – An optional flag to enable wait_for_ready mechanism.

• compression – An element of grpc.compression, e.g. grpc.compression.Gzip.

Returns:

The response value for the RPC.

Raises:

RpcError – Indicating that the RPC terminated with non-OK status. The raised RpcError will also implement grpc.Call, affording methods such as metadata, code, and details.

abstract future(request_iterator, timeout=None, metadata=None, credentials=None, wait_for_ready=None, compression=None)

Asynchronously invokes the underlying RPC on the client.

Parameters:

• request_iterator – An iterator that yields request values for the RPC.

• timeout – An optional duration of time in seconds to allow for the RPC. If None, the timeout is considered infinite.

• metadata – Optional metadata to be transmitted to the service-side of the RPC.

• credentials – An optional CallCredentials for the RPC. Only valid for secure Channel.

• wait_for_ready – An optional flag to enable wait_for_ready mechanism.

• compression – An element of grpc.compression, e.g. grpc.compression.Gzip.

Returns:

An object that is both a Call for the RPC and a Future. In the event of RPC completion, the return Call-Future’s result value will be the response message of the RPC. Should the event terminate with non-OK status, the returned Call-Future’s exception value will be an RpcError.

abstract with_call(request_iterator, timeout=None, metadata=None, credentials=None, wait_for_ready=None, compression=None)

Synchronously invokes the underlying RPC on the client.

Parameters:

• request_iterator – An iterator that yields request values for the RPC.

• timeout – An optional duration of time in seconds to allow for the RPC. If None, the timeout is considered infinite.

• metadata – Optional metadata to be transmitted to the service-side of the RPC.

• credentials – An optional CallCredentials for the RPC. Only valid for secure Channel.

• wait_for_ready – An optional flag to enable wait_for_ready mechanism.

• compression – An element of grpc.compression, e.g. grpc.compression.Gzip.

Returns:

The response value for the RPC and a Call object for the RPC.

Raises:

RpcError – Indicating that the RPC terminated with non-OK status. The raised RpcError will also be a Call for the RPC affording the RPC’s metadata, status code, and details.

class grpc.StreamStreamMultiCallable

Affords invoking a stream-stream RPC on client-side.

abstract __call__(request_iterator, timeout=None, metadata=None, credentials=None, wait_for_ready=None, compression=None)

Invokes the underlying RPC on the client.

Parameters:

• request_iterator – An iterator that yields request values for the RPC.

• timeout – An optional duration of time in seconds to allow for the RPC. If not specified, the timeout is considered infinite.

• metadata – Optional metadata to be transmitted to the service-side of the RPC.

• credentials – An optional CallCredentials for the RPC. Only valid for secure Channel.

• wait_for_ready – An optional flag to enable wait_for_ready mechanism.

• compression – An element of grpc.compression, e.g. grpc.compression.Gzip.

Returns:

An object that is a Call for the RPC, an iterator of response values, and a Future for the RPC. Drawing response values from the returned Call-iterator may raise RpcError indicating termination of the RPC with non-OK status.

Future Interfaces

exception grpc.FutureTimeoutError

Indicates that a method call on a Future timed out.

exception grpc.FutureCancelledError

Indicates that the computation underlying a Future was cancelled.

class grpc.Future

A representation of a computation in another control flow.

Computations represented by a Future may be yet to be begun, may be ongoing, or may have already completed.

abstract add_done_callback(fn)

Adds a function to be called at completion of the computation.

The callback will be passed this Future object describing the outcome of the computation. Callbacks will be invoked after the future is terminated, whether successfully or not.

If the computation has already completed, the callback will be called immediately.

Exceptions raised in the callback will be logged at ERROR level, but will not terminate any threads of execution.

Parameters:

fn – A callable taking this Future object as its single parameter.

abstract cancel()

Attempts to cancel the computation.

This method does not block.

Returns:

Returns True if the computation was canceled.

Returns False under all other circumstances, for example:

1. computation has begun and could not be canceled.

2. computation has finished

3. computation is scheduled for execution and it is impossible

   to determine its state without blocking.

Return type:

bool

abstract cancelled()

Describes whether the computation was cancelled.

This method does not block.

Returns:

Returns True if the computation was cancelled before its result became available.

Returns False under all other circumstances, for example:

1. computation was not cancelled.

2. computation’s result is available.

Return type:

bool

abstract done()

Describes whether the computation has taken place.

This method does not block.

Returns:

Returns True if the computation already executed or was cancelled. Returns False if the computation is scheduled for execution or currently executing. This is exactly opposite of the running() method’s result.

Return type:

bool

abstract exception(timeout=None)

Return the exception raised by the computation.

This method may return immediately or may block.

Parameters:

timeout – The length of time in seconds to wait for the computation to terminate or be cancelled. If None, the call will block until the computations’s termination.

Returns:

The exception raised by the computation, or None if the computation did not raise an exception.

Raises:

• FutureTimeoutError – If a timeout value is passed and the computation does not terminate within the allotted time.

• FutureCancelledError – If the computation was cancelled.

abstract result(timeout=None)

Returns the result of the computation or raises its exception.

This method may return immediately or may block.

Parameters:

timeout – The length of time in seconds to wait for the computation to finish or be cancelled. If None, the call will block until the computations’s termination.

Returns:

The return value of the computation.

Raises:

• FutureTimeoutError – If a timeout value is passed and the computation does not terminate within the allotted time.

• FutureCancelledError – If the computation was cancelled.

• Exception – If the computation raised an exception, this call will raise the same exception.

abstract running()

Describes whether the computation is taking place.

This method does not block.

Returns:

Returns True if the computation is scheduled for execution or currently executing.

Returns False if the computation already executed or was cancelled.

abstract traceback(timeout=None)

Access the traceback of the exception raised by the computation.

This method may return immediately or may block.

Parameters:

timeout – The length of time in seconds to wait for the computation to terminate or be cancelled. If None, the call will block until the computation’s termination.

Returns:

The traceback of the exception raised by the computation, or None if the computation did not raise an exception.

Raises:

• FutureTimeoutError – If a timeout value is passed and the computation does not terminate within the allotted time.

• FutureCancelledError – If the computation was cancelled.

Compression

class grpc.Compression(value)

Indicates the compression method to be used for an RPC.

NoCompression

Do not use compression algorithm.

Deflate

Use “Deflate” compression algorithm.

Gzip

Use “Gzip” compression algorithm.

Runtime Protobuf Parsing

grpc.protos(protobuf_path)

Returns a module generated by the indicated .proto file.

THIS IS AN EXPERIMENTAL API.

Use this function to retrieve classes corresponding to message definitions in the .proto file.

To inspect the contents of the returned module, use the dir function. For example:

` protos = grpc.protos("foo.proto") print(dir(protos)) `

The returned module object corresponds to the _pb2.py file generated by protoc. The path is expected to be relative to an entry on sys.path and all transitive dependencies of the file should also be resolveable from an entry on sys.path.

To completely disable the machinery behind this function, set the GRPC_PYTHON_DISABLE_DYNAMIC_STUBS environment variable to “true”.

Parameters:

protobuf_path – The path to the .proto file on the filesystem. This path must be resolveable from an entry on sys.path and so must all of its transitive dependencies.

Returns:

A module object corresponding to the message code for the indicated .proto file. Equivalent to a generated _pb2.py file.

grpc.services(protobuf_path)

Returns a module generated by the indicated .proto file.

THIS IS AN EXPERIMENTAL API.

Use this function to retrieve classes and functions corresponding to service definitions in the .proto file, including both stub and servicer definitions.

To inspect the contents of the returned module, use the dir function. For example:

` services = grpc.services("foo.proto") print(dir(services)) `

The returned module object corresponds to the _pb2_grpc.py file generated by protoc. The path is expected to be relative to an entry on sys.path and all transitive dependencies of the file should also be resolveable from an entry on sys.path.

To completely disable the machinery behind this function, set the GRPC_PYTHON_DISABLE_DYNAMIC_STUBS environment variable to “true”.

Parameters:

protobuf_path – The path to the .proto file on the filesystem. This path must be resolveable from an entry on sys.path and so must all of its transitive dependencies.

Returns:

A module object corresponding to the stub/service code for the indicated .proto file. Equivalent to a generated _pb2_grpc.py file.

grpc.protos_and_services(protobuf_path)

Returns a 2-tuple of modules corresponding to protos and services.

THIS IS AN EXPERIMENTAL API.

The return value of this function is equivalent to a call to protos and a call to services.

To completely disable the machinery behind this function, set the GRPC_PYTHON_DISABLE_DYNAMIC_STUBS environment variable to “true”.

Parameters:

protobuf_path – The path to the .proto file on the filesystem. This path must be resolveable from an entry on sys.path and so must all of its transitive dependencies.

Returns:

A 2-tuple of module objects corresponding to (protos(path), services(path)).