Merge pull request envoyproxy#177 from scilla0531/zh_trans_grpc

zh-translation: docs/root/intro/arch_overview/other_protocols/grpc.rst

docs/root/intro/arch_overview/other_protocols/grpc.rst

@@ -3,78 +3,35 @@
 gRPC
 ====
 
-`gRPC <https://www.grpc.io/>`_ is an RPC framework from Google. It uses protocol buffers as the
-underlying serialization/IDL format. At the transport layer it uses HTTP/2 for request/response
-multiplexing. Envoy has first class support for gRPC both at the transport layer as well as at the
-application layer:
+`gRPC <https://www.grpc.io/>`_ 是来自 Google 的 RPC 框架。它使用 protocol buffers 作为底层序列化/IDL（接口描述语言）格式。在传输层，它使用 HTTP/2 进行请求/响应复用。Envoy在传输层和应用层都提供对 gRPC 一流的支持：
 
-* gRPC makes use of HTTP/2 trailers to convey request status. Envoy is one of very few HTTP proxies
-  that correctly supports HTTP/2 trailers and is thus one of the few proxies that can transport
-  gRPC requests and responses.
-* The gRPC runtime for some languages is relatively immature. See :ref:`below <arch_overview_grpc_bridging>`
-  for an overview of filters that can help bring gRPC to more languages.
-* gRPC-Web is supported by a :ref:`filter <config_http_filters_grpc_web>` that allows a gRPC-Web
-  client to send requests to Envoy over HTTP/1.1 and get proxied to a gRPC server. It's under
-  active development and is expected to be the successor to the gRPC :ref:`bridge filter
-  <config_http_filters_grpc_bridge>`.
-* gRPC-JSON transcoder is supported by a :ref:`filter <config_http_filters_grpc_json_transcoder>`
-  that allows a RESTful JSON API client to send requests to Envoy over HTTP and get proxied to a
-  gRPC service.
+* gRPC 使用 HTTP/2 trailers 来传送请求状态。 Envoy 是能够正确支持 HTTP/2 trailers 的少数几个 HTTP 代理之一，因此也是少数可以传输 gRPC 请求和响应的代理之一。
+* 某些语言的 gRPC 运行时相对不成熟。有关 gRPC 引入更多语言的过滤器的概述请参见 :ref:`桥接过滤器 <arch_overview_grpc_bridging>`。
+* gRPC-Web 由一个指定的 :ref:`过滤器 <config_http_filters_grpc_web>` 支持，该过滤器允许 gRPC-Web 客户端通过 HTTP/1.1 向 Envoy 发送请求并代理到 gRPC 服务器。目前相关团队正在积极开发中，预计它将成为 gRPC :ref:`桥接过滤器 <config_http_filters_grpc_bridge>` 的后续产品。
+* gRPC-JSON 转码器由一个指定的 :ref:`过滤器 <config_http_filters_grpc_json_transcoder>` 支持，该过滤器允许 RESTful JSON API 客户端通过 HTTP 向 Envoy 发送请求并获取代理到 gRPC 服务。
 
 .. _arch_overview_grpc_bridging:
 
-gRPC bridging
+gRPC 桥接
 -------------
 
-Envoy supports two gRPC bridges:
+Envoy 支持两种 gRPC 桥接过滤器:
 
-* :ref:`grpc_http1_bridge filter <config_http_filters_grpc_bridge>` which allows gRPC requests to be sent to Envoy over
-  HTTP/1.1. Envoy then translates the requests to HTTP/2 for transport to the target server. The response is translated back to HTTP/1.1.
-  When installed, the bridge filter gathers per RPC statistics in addition to the standard array of global HTTP statistics.
-* :ref:`grpc_http1_reverse_bridge filter <config_http_filters_grpc_http1_reverse_bridge>` which allows gRPC requests to be sent to Envoy
-  and then translated to HTTP/1.1 when sent to the upstream. The response is then converted back into gRPC when sent to the downstream.
-  This filter can also optionally manage the gRPC frame header, allowing the upstream to not have to be gRPC aware at all.
+* :ref:`gRPC HTTP/1.1 桥接过滤器 <config_http_filters_grpc_bridge>` 允许将 gRPC 请求通过 HTTP/1.1 发送到 Envoy。然后，Envoy 将请求转换为 HTTP/2 传输到目标服务器。响应则被转换回 HTTP/1.1。安装后，桥接过滤器除了收集标准的全局 HTTP 统计数据外，还收集每个 RPC 的统计数据。
+* :ref:`gRPC HTTP/1.1 反向桥接过滤器 <config_http_filters_grpc_http1_reverse_bridge>` 允许将 gRPC 请求发送到 Envoy，然后在发送到上游时转换为 HTTP/1.1。在发送到下游时，响应又被转换回 gRPC。该过滤器还可以选择性地管理 gRPC 帧头，这样一来，上游就完全不用知道 gRPC 了。
 
 .. _arch_overview_grpc_services:
 
-gRPC services
+gRPC 服务
 -------------
 
-In addition to proxying gRPC on the data plane, Envoy makes use of gRPC for its
-control plane, where it :ref:`fetches configuration from management server(s)
-<config_overview>` and in filters, such as for :ref:`rate limiting
-<config_http_filters_rate_limit>` or authorization checks. We refer to these as
-*gRPC services*.
+Envoy 除了在数据平面上代理 gRPC 外，在控制平面上也使用了 gRPC，在控制平面上，它从中 :ref:`获取管理服务器的配置 <config_overview>` 以及过滤器的配置，例如将其用于 :ref:`限流 <config_http_filters_rate_limit>` 或授权检查。我们称之为 *gRPC 服务*。
 
-When specifying gRPC services, it's necessary to specify the use of either the
-:ref:`Envoy gRPC client <envoy_v3_api_field_config.core.v3.GrpcService.envoy_grpc>` or the
-:ref:`Google C++ gRPC client <envoy_v3_api_field_config.core.v3.GrpcService.google_grpc>`. We
-discuss the tradeoffs in this choice below.
+当指定 gRPC 服务时，必须指定使用 :ref:`Envoy gRPC 客户端 <envoy_v3_api_field_config.core.v3.GrpcService.envoy_grpc>` 或 :ref:`Google C++ gRPC 客户端 <envoy_v3_api_field_config.core.v3.GrpcService.google_grpc>`。 我们在下面讨论这种选择的权衡。
 
-The Envoy gRPC client is a minimal custom implementation of gRPC that makes use
-of Envoy's HTTP/2 upstream connection management. Services are specified as
-regular Envoy :ref:`clusters <arch_overview_cluster_manager>`, with regular
-treatment of :ref:`timeouts, retries <arch_overview_http_conn_man>`, endpoint
-:ref:`discovery <arch_overview_dynamic_config_eds>`/:ref:`load
-balancing/failover <arch_overview_load_balancing>`/load reporting, :ref:`circuit
-breaking <arch_overview_circuit_break>`, :ref:`health checks
-<arch_overview_health_checking>`, :ref:`outlier detection
-<arch_overview_outlier_detection>`. They share the same :ref:`connection pooling
-<arch_overview_conn_pool>` mechanism as the Envoy data plane. Similarly, cluster
-:ref:`statistics <arch_overview_statistics>` are available for gRPC services.
-Since the client is minimal, it does not include advanced gRPC features such as
-`OAuth2 <https://oauth.net/2/>`_ or `gRPC-LB
-<https://grpc.io/blog/loadbalancing>`_ lookaside.
+Envoy gRPC 客户端是 gRPC 的最小自定义实现，它使用 Envoy 的 HTTP/2 上游连接管理。服务被指定为常规的 Envoy :ref:`集群 <arch_overview_cluster_manager>`，并定期处理 :ref:`超时、重试 <arch_overview_http_conn_man>`、端点 :ref:`发现 <arch_overview_dynamic_config_eds>`、:ref:`负载均衡/故障转移 <arch_overview_load_balancing>`、负载报告、:ref:`熔断 <arch_overview_circuit_break>`、:ref:`健康检查 <arch_overview_health_checking>`、:ref:`异常检测 <arch_overview_outlier_detection>`。它们与 Envoy 的数据面共享相同的 :ref:`连接池 <arch_overview_conn_pool>` 机制。同样，集群 :ref:`统计信息 <arch_overview_statistics>` 用于 gRPC 服务。由于客户端是简化版的 gRPC 实现，因此不包括诸如 `OAuth2 <https://oauth.net/2/>`_ 或 `gRPC-LB <https://grpc.io/blog/loadbalancing>`_ 之类的高级 gRPC 功能后备。
 
-The Google C++ gRPC client is based on the reference implementation of gRPC
-provided by Google at https://github.com/grpc/grpc. It provides advanced gRPC
-features that are missing in the Envoy gRPC client. The Google C++ gRPC client
-performs its own load balancing, retries, timeouts, endpoint management, etc,
-independent of Envoy's cluster management. The Google C++ gRPC client also
-supports `custom authentication plugins
-<https://grpc.io/docs/guides/auth.html#extending-grpc-to-support-other-authentication-mechanisms>`_.
+Google C++ gRPC 客户端的实现是基于 Google 在 https://github.com/grpc/grpc 上提供的 gRPC 参考。它提供了 Envoy gRPC 客户端中缺少的高级 gRPC 功能。Google C++ gRPC 客户端独立于 Envoy 的集群管理，执行自己的负载平衡、重试、超时、端点管理等。Google C ++ gRPC客户端还支持 `自定义身份认证插件 <https://grpc.io/docs/guides/auth.html#extending-grpc-to-support-other-authentication-mechanisms>`_。
+
+在大多数情况下，当你不需要 Google C++ gRPC 客户端的高级功能时，建议使用 Envoy gRPC 客户端。这使得配置和监控更加简单。如果 Envoy gRPC 客户端中缺少你所需要的功能，则应该使用 Google C++ gRPC 客户端。
 
-It is recommended to use the Envoy gRPC client in most cases, where the advanced
-features in the Google C++ gRPC client are not required. This provides
-configuration and monitoring simplicity. Where necessary features are missing
-in the Envoy gRPC client, the Google C++ gRPC client should be used instead.