> The biggest problem I see in our client/server architecture is the ability to quickly deliver features/APIs across multiple language clients. Both Vittorio and I have seen how long it takes to implement all the different features available in Java client and port them to Node.js, C/C++/C#...etc. This effort lead by Vittorio is trying to improve on that by having some of that work done for us. Granted, not all of it will be done, but it should give us some good foundations on which to build.
To expand on it a bit further: the reason it takes us longer to get different features in is because each client implements its own network layer, parses the protocol and does type transformations (between byte[] and whatever the client expects).
IMO, the most costly things there are getting the network layer right (from experience with Node.js, it has taken a while to do so) and parsing work (not only parsing itself, but doing it in a efficient way). Network layer also includes load balancing, failover, cluster failover...etc.
From past experience, transforming from byte[] to what the client expects has never really been very problematic for me. What's been difficult here is coming up with encoding architecture that Gustavo lead, whose aim was to improve on the initial compatibility mode. But, with that now clear, understood and proven to solve our issues, the rest in this area should be fairly straightforward IMO.
Type transformation, once done, is a constant. As we add more Hot Rod operations, it's mostly the parsing that starts to become more work. Network can also become more work if instead of RPC commands you start supporting streams based commands.
gRPC solves the network (FYI: with key as HTTP header and SubchannelPicker you can do hash-aware routing) and parsing for us. I don't see the need for it to solve our type transformations for us. If it does it, great, but does it support our compatibility requirements? (I had already told Vittorio to check Gustavo on this). Type transformation is a lower prio for me, network and parsing are more important.
Hope this clarifies better my POV.
Cheers
Adrian
On 05/29/2018 03:45 PM, Vittorio Rigamonti wrote:
_______________________________________________Thanks Adrian,of course there's a marshalling work under the cover and that is reflected into the generated code (specially the accessor methods generated from the oneof clause).
My opinion is that on the client side this could be accepted, as long as the API are well defined and documented: application developer can build an adhoc decorator on the top if needed. The alternative to this is to develop a protostream equivalent for each supported language and it doesn't seem really feasible to me.
On the server side (java only) the situation is different: protobuf is optimized for streaming not for storing so probably a Protostream layer is needed.
On Mon, May 28, 2018 at 4:47 PM, Adrian Nistor <anistor@redhat.com> wrote:
Hi Vittorio,
thanks for exploring gRPC. It seems like a very elegant solution for exposing services. I'll have a look at your PoC soon.
I feel there are some remarks that need to be made regarding gRPC. gRPC is just some nice cheesy topping on top of protobuf. Google's implementation of protobuf, to be more precise.
It does not need handwritten marshallers, but the 'No need for marshaller' does not accurately describe it. Marshallers are needed and are generated under the cover by the library and so are the data objects and you are unfortunately forced to use them. That's both the good news and the bad news:) The whole thing looks very promising and friendly for many uses cases, especially for demos and PoCs :))). Nobody wants to write those marshallers. But it starts to become a nuisance if you want to use your own data objects.
There is also the ugliness and excessive memory footprint of the generated code, which is the reason Infinispan did not adopt the protobuf-java library although it did adopt protobuf as an encoding format.
The Protostream library was created as an alternative implementation to solve the aforementioned problems with the generated code. It solves this by letting the user provide their own data objects. And for the marshallers it gives you two options: a) write the marshaller yourself (hated), b) annotated your data objects and the marshaller gets generated (loved). Protostream does not currently support service definitions right now but this is something I started to investigate recently after Galder asked me if I think it's doable. I think I'll only find out after I do it:)
Adrian
On 05/28/2018 04:15 PM, Vittorio Rigamonti wrote:
Hi Infinispan developers,
I'm working on a solution for developers who need to access Infinispan services through different programming languages.
The focus is not on developing a full featured client, but rather discover the value and the limits of this approach.
- is it possible to automatically generate useful clients in different languages?
- can that clients interoperate on the same cache with the same data types?
I came out with a small prototype that I would like to submit to you and on which I would like to gather your impressions.
You can found the project here [1]: is a gRPC-based client/server architecture for Infinispan based on and EmbeddedCache, with very few features exposed atm.
Currently the project is nothing more than a poc with the following interesting features:
- client can be generated in all the grpc supported language: java, go, c++ examples are provided;
- the interface is full typed. No need for marshaller and clients build in different language can cooperate on the same cache;
The second item is my preferred one beacuse it frees the developer from data marshalling.
What do you think about?
Sounds interesting?
Can you see any flaw?
There's also a list of issues for the future [2], basically I would like to investigate these questions:
How far this architecture can go?
Topology, events, queries... how many of the Infinispan features can be fit in a grpc architecture?
Thank you
Vittorio
[1] https://github.com/rigazilla/ispn-grpc
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