Distributed Systems 1.3: RPC (Remote Procedure Call)
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- čas přidán 27. 07. 2024
- Accompanying lecture notes: www.cl.cam.ac.uk/teaching/212...
Full lecture series: • Distributed Systems le...
This video is part of an 8-lecture series on distributed systems, given as part of the undergraduate computer science course at the University of Cambridge. It is preceded by an 8-lecture course on concurrent systems for which videos are not publicly available, but slides can be found on the course web page: www.cl.cam.ac.uk/teaching/212...
I think you're great at explaining complex concepts in an accessible way. I've recently finished reading your book and I think it's amazing! It would be great if at some point you can put up more of the lectures that you do.
What's the name of the book?
@@calmvolatility2787 Designing Data-Instenstive Applications
@@martinzokov to the point, i'd also like to see more lectures of him
this is the best explanation of RPCs I've found! Thank you! From functions -> stubs -> marshalling it's much clearer now!
Thanks for making the course videos public. Very much appreciated!
Great video, just want to add some details.
RPC is a very broad topic and in fact it's relates to even more broader term API.
Nowadays the term is often used as synonym to gRPC and it's Protobuf IDL and binary Message Encoding and HTTP2 as transport protocol.
The term is used as oppose to REST API style where you acting with resources (i.e. a file) and using basic HTTP methods. The REST style looks great in books for basic CRUD (create, read, update, delete) but it's nightmare in practice. Almost all things are not "resources" but rather objects/services/actors. There is no any commonly used IDL and the HTTP methods can't cover all cases and users .
So for REST like APIs was created a separate IDL called Swagger/OpenAPI. You can describe a service in YAML file and then generate a client and documentation. This doesn't work ether because clients generation for each web framework and programming language is a goal that can't be fully achieved. The big problem here is interoperability.
The gRPC team instead just created a libraries/SDK for ALL languages so interop is good here (but still there some pitfalls).
Another architecture style that is not an RPC is a message bus, queue, Kafka streams, PubSub, CQRS, MQTT and others that are working in asynchronous or event based way.
Almost all RPC systems are built upon HTTP protocol but previously that often meant some kind of binary serialization and working upon raw TCP e.g. Java RMI, CORBA.
HTTP protocol wasn't developed to be used as a transport layer but it's well known for developers and many API gateways, proxies, load balancers and other software can be easily used. Also any developer can write at least basic API that uses HTTP.
Still it's important to remember because in many old books RPC meant some kind of binary protocol that works separately from HTTTP.
Interesting here is a Java RMI. You can expose any java class and call it from another computer. All parameters will be serialized by Java itself and no any additional IDL needed. But it had a lot of problems with compatibility because you may change order of fields and this may break the serialization. It was widely used for internal network calls and with JavaEE stack.
Go/Golang also has a similar thing and no IDL needed and it may even use HTTP as a transport protocol and uses own GOB serialization format. betterprogramming.pub/rpc-in-golang-19661033942
Brief history:
1. CORBA was used in early 90tes. Very complicated
2. JavaRMI. It's not used today but still a good solution for microservices written in Java
3. XML-RPC was first HTTP based protocol but it doesn't defined any IDL/schema
4. SOAP which is XML-RPC + WSDL schema. All enterprise and JavaEE based apps used it. This was a nightmare because XML is a bad serialization format. For example everyone serialized ditcs/maps in different way. Date format is also often was different.
5. "REST" in fact that means not a protocol but a style when HTTP is used not as a transport but as a supper protocol i.e. use GET/POST/PUT/DELETE methods, reuse HTTP status codes and JSON as a serialization format.
6. JSON-RPC similar to XML-RPC but with JSON as a serialization. It's not popular but used as a most simple and clear protocol.
7. gRPC is used mostly for internal interaction between microservices or for low latency APIs.
8. Cap’n Proto is also very interesting but not widely used
An IPC (Inter Process Communication) term is also related and means an RPC between two programs inside of one computer. Here are used COM/ActiveX on Windows, DBus in Linux and UBus in OpenWRT that are working upon a UNIX socket. And here is interesting that this internal RPC systems also can be exposed to a network via HTTP gateways. For example in OpenWrt the uhttpd web server can expose local UBus via JSON-RPC so can be called from outside.
Also see Wikipedia article en.wikipedia.org/wiki/Remote_procedure_call
Serialization formats are also can be very different: BSON, MessagePack, AVRO and even plain CSV is often a good solution. Choosing a good format may scientifically improve API speed
Hey, do you do online class regard Distributed System?
@@williamnks6654 no, just watched few videos here. Martin made great lectures!
@@stokitko This was amazing! I read this whole comment and i learned alot thanks!
Thank you so much for making this awesome series of videos public! Thank you, a thousand times thank you!
Love from Pakistan... the best ever explanation of RPC on youtube... Martin you are freakin legend 👍👍
Amazing how you explain complex concepts in a very simple a clear way! I couldn't understand RPC until you explain
Appreciate these being public - I really enjoy the very practical examples and explanations to supplement my classes more theoretical lectures
to-the-point, very good explanation @Martin, many thanks for sharing.
Still trying to grasp this topic and your video improved my understanding significantly, examples and code are very important so thank you for this video!
now RPC makes sense for me!
Thank you for your great explanations
I been searching for this for many days...this helped me understand those API calls in Java
thank you so much for making this video public. That's really helpful.
The best explanation of RPC.
Thanks for such detailed and clear explanation!
Client-server example: online payments
Remote Procedure Call (RPC) example [2:23]
(sequence diagram) [4:06]
Remote Procedure Call (RPC) [6:46]
In practice... [7:31]
RPC history [9:00]
RPC/REST in JavaScript [11:09]
RPC in enterprise systems [14:20]
gRPC IDL example [17:19]
Hey, are you good at it ?I looking for someone who could give an online class.
Very good explanation it is the best among all so far. Keep uploading more
Thank you so much for the perfect explanation
Thank you sir, you explain so clearly and calmly
Thanks for your sharing! I got the concept of RPC very long ago, but never understand what it exactly does and which case it is suitable to use. Your video answers all of my questions, thank you!
bestes video was ich gefunden habe. alles andere hat mega genervt.
aber wundert mich auch nicht wegen cambridge prof titel xD
Perfect explained, thanks!
This is great! Thank you so much Martin
Absolutely amazing video thank you
It's now I know REST is also a type of RPC. thanks.
Great explanation, Thanks a lot.
Thank you so much for this Sir!!
solved the problem harassing me for 2 days. Thank you!
Great explanation. Thanks 👍🏻
Awesome Explanation
Done thanks!
17:00 interface def language
fantastic!! Thank you very much!
great video, thanks
Assume description. I love this video much ☺️
Can we just take a moment to appreciate the code formatting in these slides??
Good lecture but 2 small extras as for microservices:
- microservices is just much more than "splitting a large software application into multiple services" - the splitting can be (and usually is) done extremely wrong, so it doesn't have the good qualities distributed system should have, and then it's called not microservice, but distributed monolith 🙂
- microservices aren't the same as SOA: microservices are a particular way of doing SOA, where we have decoupled not only our modules from each other, but we are also decoupled from platform: no vendor lock in, no costy Oracle or SQL Server licenses, all SOAish stuff like EJB, SOAP, distributed transactions, enterprise event buses, etc is dropped in favor of lightweight protocols like HTTP and free choice of technologies (any database, any runtime like Java, Python, NodeJS, etc)
This video helps me a lot. Would you talk other middle-wares like message queue service?
So say you have access to both code bases. For any kind of RPC middleware, how would you go about finding the implementation of a function call on the server end? I ask because the implementation name isn't always the same as the stub name.
will this is work in between 2 TCP socket server applications , or does this only work with https applications
A little out of context but does anybody know if there is a good tutorial how to build a simple RPC communication between two "devices" in docker? This video explains the theory perfectly, but I desperately need some practical help.
I was wondering if RPC is conceptually similar to REST, then why it is so widely used in distributed system? What if we use REST in distributed system?
It says "Location transparency" is for hiding whether the resource is local or remote, but wouldn't transparency imply it is not hidden? I feel like "Location opaqueness" makes more sense
How is RPC and REST HTTP call different if both can use JSON?
They are different names for pretty much the same concept. Some people distinguish between RPC and REST, making some subtle distinctions about how exactly the API is structured, but in my opinion it's mostly a distinction without a difference.
@@kleppmann Got it 👍, Thank you :)
Hey Martin, you might be very busy, I was just wondering if you would know anyone who could give online class regard a Distributed Systems? thank you
What is the font family name at 2:38, thanks!
Maybe the topic is not related to 'Distributed system' but to 'Software design', but still SOA and microservices are two different things...
Apparently, Martin enjoys #Maroon.
are you from.scotland?
5:30 Why is it called marshalling? Is it because of historic reasons? Why not call it serialisation?
Both terms are used, and they mean pretty much the same thing. I avoided "serialisation" in this course because it's easy to confuse with the concept of "serialisability" that appears in concurrent transaction execution.
@@kleppmann Makes sense. Thank you for responding :)
nit: grpc doesn't stand for google rpc
hast du discord?