I know how this works

I know how this works

This assumes you have a lot of experience and significant knowlege of computer science. It is not for beginners.

What it is

parigot is an RPC toolkit for building microservices. By virtue of its API, it ran run a collection of microservices as a single process (e.g. a debugger works) or a separate processes connected by a network.

Setup

• Start with the hello world example
• Copy all the files in helloworld to a new directory under examples, like examples/myprog.

a simple program

• “program” here means a program that runs to completion.
• Define the protocols between your services as a .proto file. You can look at the greeting service.
• The .proto should be placed in the same place as they are in helloworld, the top level directory “proto”.
• Generate code via the make generate approach from the helloworld Makefile.
• Define a main() that is your program, like helloworld. It is expected that this program will use ExitSelf() to end at some point.
• Use LaunchClient() to start your program. It’ll return a future.
• On Success() proceed to your program proper.
• Call methods on other services via the generated guest code like this for greeting service.
• You must run the loop that checks for events. For programs that run to completion, MustRunClient is the usual approach.

a simple service

• A simple service should have a main that sets up the service. Here is the example from greenting/main.go
• As above, you need to launch the service and deal with the future on startup. Although, the generated Init() function for your type is easier than doing a bunch of setup. Here is the generated Init from greeting service.
• If you need references to other services to implement your services, do that in the Ready method that is called just after launch.
  • Use Locate()to find the other service. Locate is defined by the generated code of the other service,e.g. ServiceINeed.Locate().
• Implement the methods from the .proto. It’s best to do them with the two parts that differ by a capital first letter. It makes for easier unit testing. An example is here
• Methods defined in the .proto will automatically be hooked up to the event loop.
• You can call [Run()] that has been generated for your type. The implementations of your methods will be called when other services or programs call them.

notes

parallelism

• A service or program is single threaded, but different services can and do run in parallel.
• We use futures to deal with the single-threadedness. Within a service or program you should not block. Nor should you bother with locks.
• Methods in a service need to return in <50ms or it should it return an id that be “polled” later. Services that have methods that take too long may be killed by parigot.

WASM

• Client programs are WASM executable programs
  • Currently only golang support, but that’s not not for long.
  • No built in support for WASI or WASIX.

ids

• Numerous built-in types are <BLAH>Id like HostId,ServiceId, etc. These are typed, random, 112 bit values. Two 64bit unsigned ints - 2 bytes for typing.
• There is a tool, boilerplateid that can create new types of Ids if you want your own. See the Makefile of parigot for examples.