comparison osx/include/capnp/rpc.h @ 49:3ab5a40c4e3b

Add Capnp and KJ builds for OSX

+// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#ifndef CAPNP_RPC_H_
+#define CAPNP_RPC_H_
+
+#if defined(__GNUC__) && !defined(CAPNP_HEADER_WARNINGS)
+#pragma GCC system_header
+#endif
+
+#include "capability.h"
+#include "rpc-prelude.h"
+
+namespace capnp {
+
+template <typename VatId, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult>
+class VatNetwork;
+template <typename SturdyRefObjectId>
+class SturdyRefRestorer;
+
+template <typename VatId>
+class BootstrapFactory: public _::BootstrapFactoryBase {
+  // Interface that constructs per-client bootstrap interfaces. Use this if you want each client
+  // who connects to see a different bootstrap interface based on their (authenticated) VatId.
+  // This allows an application to bootstrap off of the authentication performed at the VatNetwork
+  // level. (Typically VatId is some sort of public key.)
+  //
+  // This is only useful for multi-party networks. For TwoPartyVatNetwork, there's no reason to
+  // use a BootstrapFactory; just specify a single bootstrap capability in this case.
+
+public:
+  virtual Capability::Client createFor(typename VatId::Reader clientId) = 0;
+  // Create a bootstrap capability appropriate for exposing to the given client. VatNetwork will
+  // have authenticated the client VatId before this is called.
+
+private:
+  Capability::Client baseCreateFor(AnyStruct::Reader clientId) override;
+};
+
+template <typename VatId>
+class RpcSystem: public _::RpcSystemBase {
+  // Represents the RPC system, which is the portal to objects available on the network.
+  //
+  // The RPC implementation sits on top of an implementation of `VatNetwork`.  The `VatNetwork`
+  // determines how to form connections between vats -- specifically, two-way, private, reliable,
+  // sequenced datagram connections.  The RPC implementation determines how to use such connections
+  // to manage object references and make method calls.
+  //
+  // See `makeRpcServer()` and `makeRpcClient()` below for convenient syntax for setting up an
+  // `RpcSystem` given a `VatNetwork`.
+  //
+  // See `ez-rpc.h` for an even simpler interface for setting up RPC in a typical two-party
+  // client/server scenario.
+
+public:
+  template <typename ProvisionId, typename RecipientId,
+            typename ThirdPartyCapId, typename JoinResult>
+  RpcSystem(
+      VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+      kj::Maybe<Capability::Client> bootstrapInterface,
+      kj::Maybe<RealmGateway<>::Client> gateway = nullptr);
+
+  template <typename ProvisionId, typename RecipientId,
+            typename ThirdPartyCapId, typename JoinResult>
+  RpcSystem(
+      VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+      BootstrapFactory<VatId>& bootstrapFactory,
+      kj::Maybe<RealmGateway<>::Client> gateway = nullptr);
+
+  template <typename ProvisionId, typename RecipientId,
+            typename ThirdPartyCapId, typename JoinResult,
+            typename LocalSturdyRefObjectId>
+  RpcSystem(
+      VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+      SturdyRefRestorer<LocalSturdyRefObjectId>& restorer);
+
+  RpcSystem(RpcSystem&& other) = default;
+
+  Capability::Client bootstrap(typename VatId::Reader vatId);
+  // Connect to the given vat and return its bootstrap interface.
+
+  Capability::Client restore(typename VatId::Reader hostId, AnyPointer::Reader objectId)
+      KJ_DEPRECATED("Please transition to using a bootstrap interface instead.");
+  // ** DEPRECATED **
+  //
+  // Restores the given SturdyRef from the network and return the capability representing it.
+  //
+  // `hostId` identifies the host from which to request the ref, in the format specified by the
+  // `VatNetwork` in use.  `objectId` is the object ID in whatever format is expected by said host.
+  //
+  // This method will be removed in a future version of Cap'n Proto. Instead, please transition
+  // to using bootstrap(), which is equivalent to calling restore() with a null `objectId`.
+  // You may emulate the old concept of object IDs by exporting a bootstrap interface which has
+  // methods that can be used to obtain other capabilities by ID.
+
+  void setFlowLimit(size_t words);
+  // Sets the incoming call flow limit. If more than `words` worth of call messages have not yet
+  // received responses, the RpcSystem will not read further messages from the stream. This can be
+  // used as a crude way to prevent a resource exhaustion attack (or bug) in which a peer makes an
+  // excessive number of simultaneous calls that consume the receiver's RAM.
+  //
+  // There are some caveats. When over the flow limit, all messages are blocked, including returns.
+  // If the outstanding calls are themselves waiting on calls going in the opposite direction, the
+  // flow limit may prevent those calls from completing, leading to deadlock. However, a
+  // sufficiently high limit should make this unlikely.
+  //
+  // Note that a call's parameter size counts against the flow limit until the call returns, even
+  // if the recipient calls releaseParams() to free the parameter memory early. This is because
+  // releaseParams() may simply indicate that the parameters have been forwarded to another
+  // machine, but are still in-memory there. For illustration, say that Alice made a call to Bob
+  // who forwarded the call to Carol. Bob has imposed a flow limit on Alice. Alice's calls are
+  // being forwarded to Carol, so Bob never keeps the parameters in-memory for more than a brief
+  // period. However, the flow limit counts all calls that haven't returned, even if Bob has
+  // already freed the memory they consumed. You might argue that the right solution here is
+  // instead for Carol to impose her own flow limit on Bob. This has a serious problem, though:
+  // Bob might be forwarding requests to Carol on behalf of many different parties, not just Alice.
+  // If Alice can pump enough data to hit the Bob -> Carol flow limit, then those other parties
+  // will be disrupted. Thus, we can only really impose the limit on the Alice -> Bob link, which
+  // only affects Alice. We need that one flow limit to limit Alice's impact on the whole system,
+  // so it has to count all in-flight calls.
+  //
+  // In Sandstorm, flow limits are imposed by the supervisor on calls coming out of a grain, in
+  // order to prevent a grain from inundating the system with in-flight calls. In practice, the
+  // main time this happens is when a grain is pushing a large file download and doesn't implement
+  // proper cooperative flow control.
+};
+
+template <typename VatId, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult>
+RpcSystem<VatId> makeRpcServer(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    Capability::Client bootstrapInterface);
+// Make an RPC server.  Typical usage (e.g. in a main() function):
+//
+//    MyEventLoop eventLoop;
+//    kj::WaitScope waitScope(eventLoop);
+//    MyNetwork network;
+//    MyMainInterface::Client bootstrap = makeMain();
+//    auto server = makeRpcServer(network, bootstrap);
+//    kj::NEVER_DONE.wait(waitScope);  // run forever
+//
+// See also ez-rpc.h, which has simpler instructions for the common case of a two-party
+// client-server RPC connection.
+
+template <typename VatId, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult, typename RealmGatewayClient,
+          typename InternalRef = _::InternalRefFromRealmGatewayClient<RealmGatewayClient>,
+          typename ExternalRef = _::ExternalRefFromRealmGatewayClient<RealmGatewayClient>>
+RpcSystem<VatId> makeRpcServer(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    Capability::Client bootstrapInterface, RealmGatewayClient gateway);
+// Make an RPC server for a VatNetwork that resides in a different realm from the application.
+// The given RealmGateway is used to translate SturdyRefs between the app's ("internal") format
+// and the network's ("external") format.
+
+template <typename VatId, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult>
+RpcSystem<VatId> makeRpcServer(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    BootstrapFactory<VatId>& bootstrapFactory);
+// Make an RPC server that can serve different bootstrap interfaces to different clients via a
+// BootstrapInterface.
+
+template <typename VatId, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult, typename RealmGatewayClient,
+          typename InternalRef = _::InternalRefFromRealmGatewayClient<RealmGatewayClient>,
+          typename ExternalRef = _::ExternalRefFromRealmGatewayClient<RealmGatewayClient>>
+RpcSystem<VatId> makeRpcServer(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    BootstrapFactory<VatId>& bootstrapFactory, RealmGatewayClient gateway);
+// Make an RPC server that can serve different bootstrap interfaces to different clients via a
+// BootstrapInterface and communicates with a different realm than the application is in via a
+// RealmGateway.
+
+template <typename VatId, typename LocalSturdyRefObjectId,
+          typename ProvisionId, typename RecipientId, typename ThirdPartyCapId, typename JoinResult>
+RpcSystem<VatId> makeRpcServer(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    SturdyRefRestorer<LocalSturdyRefObjectId>& restorer)
+    KJ_DEPRECATED("Please transition to using a bootstrap interface instead.");
+// ** DEPRECATED **
+//
+// Create an RPC server which exports multiple main interfaces by object ID. The `restorer` object
+// can be used to look up objects by ID.
+//
+// Please transition to exporting only one interface, which is known as the "bootstrap" interface.
+// For backwards-compatibility with old clients, continue to implement SturdyRefRestorer, but
+// return the new bootstrap interface when the request object ID is null. When new clients connect
+// and request the bootstrap interface, they will get that interface. Eventually, once all clients
+// are updated to request only the bootstrap interface, stop implementing SturdyRefRestorer and
+// switch to passing the bootstrap capability itself as the second parameter to `makeRpcServer()`.
+
+template <typename VatId, typename ProvisionId,
+          typename RecipientId, typename ThirdPartyCapId, typename JoinResult>
+RpcSystem<VatId> makeRpcClient(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network);
+// Make an RPC client.  Typical usage (e.g. in a main() function):
+//
+//    MyEventLoop eventLoop;
+//    kj::WaitScope waitScope(eventLoop);
+//    MyNetwork network;
+//    auto client = makeRpcClient(network);
+//    MyCapability::Client cap = client.restore(hostId, objId).castAs<MyCapability>();
+//    auto response = cap.fooRequest().send().wait(waitScope);
+//    handleMyResponse(response);
+//
+// See also ez-rpc.h, which has simpler instructions for the common case of a two-party
+// client-server RPC connection.
+
+template <typename VatId, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult, typename RealmGatewayClient,
+          typename InternalRef = _::InternalRefFromRealmGatewayClient<RealmGatewayClient>,
+          typename ExternalRef = _::ExternalRefFromRealmGatewayClient<RealmGatewayClient>>
+RpcSystem<VatId> makeRpcClient(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    RealmGatewayClient gateway);
+// Make an RPC client for a VatNetwork that resides in a different realm from the application.
+// The given RealmGateway is used to translate SturdyRefs between the app's ("internal") format
+// and the network's ("external") format.
+
+template <typename SturdyRefObjectId>
+class SturdyRefRestorer: public _::SturdyRefRestorerBase {
+  // ** DEPRECATED **
+  //
+  // In Cap'n Proto 0.4.x, applications could export multiple main interfaces identified by
+  // object IDs. The callback used to map object IDs to objects was `SturdyRefRestorer`, as we
+  // imagined this would eventually be used for restoring SturdyRefs as well. In practice, it was
+  // never used for real SturdyRefs, only for exporting singleton objects under well-known names.
+  //
+  // The new preferred strategy is to export only a _single_ such interface, called the
+  // "bootstrap interface". That interface can itself have methods for obtaining other objects, of
+  // course, but that is up to the app. `SturdyRefRestorer` exists for backwards-compatibility.
+  //
+  // Hint:  Use SturdyRefRestorer<capnp::Text> to define a server that exports services under
+  //   string names.
+
+public:
+  virtual Capability::Client restore(typename SturdyRefObjectId::Reader ref)
+      KJ_DEPRECATED(
+          "Please transition to using bootstrap interfaces instead of SturdyRefRestorer.") = 0;
+  // Restore the given object, returning a capability representing it.
+
+private:
+  Capability::Client baseRestore(AnyPointer::Reader ref) override final;
+};
+
+// =======================================================================================
+// VatNetwork
+
+class OutgoingRpcMessage {
+  // A message to be sent by a `VatNetwork`.
+
+public:
+  virtual AnyPointer::Builder getBody() = 0;
+  // Get the message body, which the caller may fill in any way it wants.  (The standard RPC
+  // implementation initializes it as a Message as defined in rpc.capnp.)
+
+  virtual void send() = 0;
+  // Send the message, or at least put it in a queue to be sent later.  Note that the builder
+  // returned by `getBody()` remains valid at least until the `OutgoingRpcMessage` is destroyed.
+};
+
+class IncomingRpcMessage {
+  // A message received from a `VatNetwork`.
+
+public:
+  virtual AnyPointer::Reader getBody() = 0;
+  // Get the message body, to be interpreted by the caller.  (The standard RPC implementation
+  // interprets it as a Message as defined in rpc.capnp.)
+};
+
+template <typename VatId, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult>
+class VatNetwork: public _::VatNetworkBase {
+  // Cap'n Proto RPC operates between vats, where a "vat" is some sort of host of objects.
+  // Typically one Cap'n Proto process (in the Unix sense) is one vat.  The RPC system is what
+  // allows calls between objects hosted in different vats.
+  //
+  // The RPC implementation sits on top of an implementation of `VatNetwork`.  The `VatNetwork`
+  // determines how to form connections between vats -- specifically, two-way, private, reliable,
+  // sequenced datagram connections.  The RPC implementation determines how to use such connections
+  // to manage object references and make method calls.
+  //
+  // The most common implementation of VatNetwork is TwoPartyVatNetwork (rpc-twoparty.h).  Most
+  // simple client-server apps will want to use it.  (You may even want to use the EZ RPC
+  // interfaces in `ez-rpc.h` and avoid all of this.)
+  //
+  // TODO(someday):  Provide a standard implementation for the public internet.
+
+public:
+  class Connection;
+
+  struct ConnectionAndProvisionId {
+    // Result of connecting to a vat introduced by another vat.
+
+    kj::Own<Connection> connection;
+    // Connection to the new vat.
+
+    kj::Own<OutgoingRpcMessage> firstMessage;
+    // An already-allocated `OutgoingRpcMessage` associated with `connection`.  The RPC system will
+    // construct this as an `Accept` message and send it.
+
+    Orphan<ProvisionId> provisionId;
+    // A `ProvisionId` already allocated inside `firstMessage`, which the RPC system will use to
+    // build the `Accept` message.
+  };
+
+  class Connection: public _::VatNetworkBase::Connection {
+    // A two-way RPC connection.
+    //
+    // This object may represent a connection that doesn't exist yet, but is expected to exist
+    // in the future.  In this case, sent messages will automatically be queued and sent once the
+    // connection is ready, so that the caller doesn't need to know the difference.
+
+  public:
+    // Level 0 features ----------------------------------------------
+
+    virtual typename VatId::Reader getPeerVatId() = 0;
+    // Returns the connected vat's authenticated VatId. It is the VatNetwork's responsibility to
+    // authenticate this, so that the caller can be assured that they are really talking to the
+    // identified vat and not an imposter.
+
+    virtual kj::Own<OutgoingRpcMessage> newOutgoingMessage(uint firstSegmentWordSize) override = 0;
+    // Allocate a new message to be sent on this connection.
+    //
+    // If `firstSegmentWordSize` is non-zero, it should be treated as a hint suggesting how large
+    // to make the first segment.  This is entirely a hint and the connection may adjust it up or
+    // down.  If it is zero, the connection should choose the size itself.
+
+    virtual kj::Promise<kj::Maybe<kj::Own<IncomingRpcMessage>>> receiveIncomingMessage() override = 0;
+    // Wait for a message to be received and return it.  If the read stream cleanly terminates,
+    // return null.  If any other problem occurs, throw an exception.
+
+    virtual kj::Promise<void> shutdown() override KJ_WARN_UNUSED_RESULT = 0;
+    // Waits until all outgoing messages have been sent, then shuts down the outgoing stream. The
+    // returned promise resolves after shutdown is complete.
+
+  private:
+    AnyStruct::Reader baseGetPeerVatId() override;
+  };
+
+  // Level 0 features ------------------------------------------------
+
+  virtual kj::Maybe<kj::Own<Connection>> connect(typename VatId::Reader hostId) = 0;
+  // Connect to a VatId.  Note that this method immediately returns a `Connection`, even
+  // if the network connection has not yet been established.  Messages can be queued to this
+  // connection and will be delivered once it is open.  The caller must attempt to read from the
+  // connection to verify that it actually succeeded; the read will fail if the connection
+  // couldn't be opened.  Some network implementations may actually start sending messages before
+  // hearing back from the server at all, to avoid a round trip.
+  //
+  // Returns nullptr if `hostId` refers to the local host.
+
+  virtual kj::Promise<kj::Own<Connection>> accept() = 0;
+  // Wait for the next incoming connection and return it.
+
+  // Level 4 features ------------------------------------------------
+  // TODO(someday)
+
+private:
+  kj::Maybe<kj::Own<_::VatNetworkBase::Connection>>
+      baseConnect(AnyStruct::Reader hostId) override final;
+  kj::Promise<kj::Own<_::VatNetworkBase::Connection>> baseAccept() override final;
+};
+
+// =======================================================================================
+// ***************************************************************************************
+// Inline implementation details start here
+// ***************************************************************************************
+// =======================================================================================
+
+template <typename VatId>
+Capability::Client BootstrapFactory<VatId>::baseCreateFor(AnyStruct::Reader clientId) {
+  return createFor(clientId.as<VatId>());
+}
+
+template <typename SturdyRef, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult>
+kj::Maybe<kj::Own<_::VatNetworkBase::Connection>>
+    VatNetwork<SturdyRef, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>::
+    baseConnect(AnyStruct::Reader ref) {
+  auto maybe = connect(ref.as<SturdyRef>());
+  return maybe.map([](kj::Own<Connection>& conn) -> kj::Own<_::VatNetworkBase::Connection> {
+    return kj::mv(conn);
+  });
+}
+
+template <typename SturdyRef, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult>
+kj::Promise<kj::Own<_::VatNetworkBase::Connection>>
+    VatNetwork<SturdyRef, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>::baseAccept() {
+  return accept().then(
+      [](kj::Own<Connection>&& connection) -> kj::Own<_::VatNetworkBase::Connection> {
+    return kj::mv(connection);
+  });
+}
+
+template <typename SturdyRef, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult>
+AnyStruct::Reader VatNetwork<
+    SturdyRef, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>::
+    Connection::baseGetPeerVatId() {
+  return getPeerVatId();
+}
+
+template <typename SturdyRef>
+Capability::Client SturdyRefRestorer<SturdyRef>::baseRestore(AnyPointer::Reader ref) {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+  return restore(ref.getAs<SturdyRef>());
+#pragma GCC diagnostic pop
+}
+
+template <typename VatId>
+template <typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult>
+RpcSystem<VatId>::RpcSystem(
+      VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+      kj::Maybe<Capability::Client> bootstrap,
+      kj::Maybe<RealmGateway<>::Client> gateway)
+    : _::RpcSystemBase(network, kj::mv(bootstrap), kj::mv(gateway)) {}
+
+template <typename VatId>
+template <typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult>
+RpcSystem<VatId>::RpcSystem(
+      VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+      BootstrapFactory<VatId>& bootstrapFactory,
+      kj::Maybe<RealmGateway<>::Client> gateway)
+    : _::RpcSystemBase(network, bootstrapFactory, kj::mv(gateway)) {}
+
+template <typename VatId>
+template <typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult,
+          typename LocalSturdyRefObjectId>
+RpcSystem<VatId>::RpcSystem(
+      VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+      SturdyRefRestorer<LocalSturdyRefObjectId>& restorer)
+    : _::RpcSystemBase(network, restorer) {}
+
+template <typename VatId>
+Capability::Client RpcSystem<VatId>::bootstrap(typename VatId::Reader vatId) {
+  return baseBootstrap(_::PointerHelpers<VatId>::getInternalReader(vatId));
+}
+
+template <typename VatId>
+Capability::Client RpcSystem<VatId>::restore(
+    typename VatId::Reader hostId, AnyPointer::Reader objectId) {
+  return baseRestore(_::PointerHelpers<VatId>::getInternalReader(hostId), objectId);
+}
+
+template <typename VatId>
+inline void RpcSystem<VatId>::setFlowLimit(size_t words) {
+  baseSetFlowLimit(words);
+}
+
+template <typename VatId, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult>
+RpcSystem<VatId> makeRpcServer(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    Capability::Client bootstrapInterface) {
+  return RpcSystem<VatId>(network, kj::mv(bootstrapInterface));
+}
+
+template <typename VatId, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult,
+          typename RealmGatewayClient, typename InternalRef, typename ExternalRef>
+RpcSystem<VatId> makeRpcServer(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    Capability::Client bootstrapInterface, RealmGatewayClient gateway) {
+  return RpcSystem<VatId>(network, kj::mv(bootstrapInterface),
+      gateway.template castAs<RealmGateway<>>());
+}
+
+template <typename VatId, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult>
+RpcSystem<VatId> makeRpcServer(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    BootstrapFactory<VatId>& bootstrapFactory) {
+  return RpcSystem<VatId>(network, bootstrapFactory);
+}
+
+template <typename VatId, typename ProvisionId, typename RecipientId,
+          typename ThirdPartyCapId, typename JoinResult,
+          typename RealmGatewayClient, typename InternalRef, typename ExternalRef>
+RpcSystem<VatId> makeRpcServer(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    BootstrapFactory<VatId>& bootstrapFactory, RealmGatewayClient gateway) {
+  return RpcSystem<VatId>(network, bootstrapFactory, gateway.template castAs<RealmGateway<>>());
+}
+
+template <typename VatId, typename LocalSturdyRefObjectId,
+          typename ProvisionId, typename RecipientId, typename ThirdPartyCapId, typename JoinResult>
+RpcSystem<VatId> makeRpcServer(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    SturdyRefRestorer<LocalSturdyRefObjectId>& restorer) {
+  return RpcSystem<VatId>(network, restorer);
+}
+
+template <typename VatId, typename ProvisionId,
+          typename RecipientId, typename ThirdPartyCapId, typename JoinResult>
+RpcSystem<VatId> makeRpcClient(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network) {
+  return RpcSystem<VatId>(network, nullptr);
+}
+
+template <typename VatId, typename ProvisionId,
+          typename RecipientId, typename ThirdPartyCapId, typename JoinResult,
+          typename RealmGatewayClient, typename InternalRef, typename ExternalRef>
+RpcSystem<VatId> makeRpcClient(
+    VatNetwork<VatId, ProvisionId, RecipientId, ThirdPartyCapId, JoinResult>& network,
+    RealmGatewayClient gateway) {
+  return RpcSystem<VatId>(network, nullptr, gateway.template castAs<RealmGateway<>>());
+}
+
+}  // namespace capnp
+
+#endif  // CAPNP_RPC_H_