example_ae/

Introduction

There are some problems using protobuf with appengine; notably, its use of unsafe. Here are some directions about how to use go-rpcgen on AppEngine.

Deploying to AppEngine

When deploying to AppEngine, you need two things:

1. The go-rpcgen/webrpc package
2. Sanitized .pb.go files

I have provided scripts in the root of the repository to help out with these.

Getting go-rpcgen/webrpc in your app

The ae_install.sh script should be run from your appengine project's root directory (the one containing app.yaml) and will copy the webrpc package into the proper place. The webrpc package contains proto support, but the go1 version of appengine will ignore this file.

Getting sanitized protobufs in your app

The ae_protoc.go script (which relies on protoc-gen-go being in your PATH) will compile (for Go only) all of the .proto files specified on the command-line.

The script has been changed since its previous version to generate both a full .pb.go for use in normal applications and a .ae.go for use in appengine. They both have compilation guards which cause them to be executed in the proper context.

Both proto files are compiled with support for web services only (to avoid the dependency on the codec package) and the script will sanitize the duplicate .ae.go file to remove references to goprotobuf. A side-effect of the sanitization is that there will no longer be a .String() method on the generated objects under appengine; you may add one manually if you wish, but I would recommend doing it in an adjacent .go file (with the proper +build guard for appengine) so that regeneration won't kill it.

Testing This Example

To test this out, you will probably need go1 installed locally so that you can compile non-appengine binaries. The appengine go wrapper script in particular doesn't like arguments to go run though it may be possible to use.

Here are the basic steps:

• Update app.yaml with your application name and the latest Go SDK Version

• Execute the following (in the example_ae directory) to run locally:

    ../ae_install.sh
    ../ae_protoc.sh whoami/*.proto
    dev_appserver.py .
  

• Then, in another shell (since dev_appserver blocks):

    go run client/client.go http://localhost:6060/
  

• Run the following to test remotely:

    appcfg.py update .
    go run client/client.go http://path-to-your-app.appspot.com/