02.12.2020

Category: Proto3 extend message

Proto3 extend message

GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Already on GitHub? Sign in to your account. Describe the problem you are trying to solve.

Lot's of DRY code in statically typed languages.

Building a messaging platform with GRPC and Protobuf - Guven Iscan and Claus Jorgensen

Describe the solution you'd like I'd like you to add inheritance to current proto3 or at least the future protobuf versions. An example is:. Alternatives you've considered I know about composition and it's really not a cure. Additional context I know that protobuf favors composition over inheritance but it's really not a cure to remove inheritance completely.

Statically typed languages like Java or C suffer from composition only approach. These languages cannot use polymorphism because all the messages have the same parent GeneratedMessageV3.

Extending Protobuf: dynamic messages

If inheritance was available, we could use polymorphism. Instead of having to write:. It leads to wider test suites that take more time to execute. I could go on but I hope I explained myself.

If not, just ask and I'll clarify it. To quote the Protocol Buffers tutorial : "Don't go looking for facilities similar to class inheritance, though — protocol buffers don't do that. Instead of inheritance, Protocol Buffers tends to favor composition as a pattern. GRPC is not doing "favor composition over inheritance" pattern, it's applying "remove inheritance" pattern.

There are cases when inheritance is more suitable. Just because it's a good practice to " favor somehing ", it doesn't mean it should be removed completely or not implemented at all. Yes, most of the time we should use public transport because it's better for Earth. On the other hand, you have cases when driving a car is a better option, e. How are you supposed to implement inheritance in a language that doesn't support inheritance like Rust or Go which only support struct-like data types?

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proto3 extend message

New issue.This guide describes how to use the protocol buffer language to structure your protocol buffer data, including. It covers the proto2 version of the protocol buffers language: for information on the newer proto3 syntax, see the Proto3 Language Guide.

Prefer Proto3 While proto2 will continue to be supported, we encourage new code to use proto3 instead, which is easier to use and supports more languages. This is a reference guide — for a step by step example that uses many of the features described in this document, see the tutorial for your chosen language.

Defining A Message Type First let's look at a very simple example. Let's say you want to define a search request message format, where each search request has a query string, the particular page of results you are interested in, and a number of results per page.

Here's the. Each field has a name and a type. However, you can also specify composite types for your fields, including enumerations and other message types. Assigning Field Numbers As you can see, each field in the message definition has a unique number. These numbers are used to identify your fields in the message binary formatand should not be changed once your message type is in use.

Note that field numbers in the range 1 through 15 take one byte to encode, including the field number and the field's type you can find out more about this in Protocol Buffer Encoding. Field numbers in the range 16 through take two bytes. So you should reserve the field numbers 1 through 15 for very frequently occurring message elements.

Remember to leave some room for frequently occurring elements that might be added in the future. The smallest field number you can specify is 1, and the largest is 2 29 - 1, orYou also cannot use the numbers through FieldDescriptor::kFirstReservedNumber through FieldDescriptor::kLastReservedNumberas they are reserved for the Protocol Buffers implementation - the protocol buffer compiler will complain if you use one of these reserved numbers in your.

Similarly, you cannot use any previously reserved field numbers.

proto3 extend message

Specifying Field Rules You specify that message fields are one of the following: required : a well-formed message must have exactly one of this field. The order of the repeated values will be preserved. For historical reasons, repeated fields of scalar numeric types aren't encoded as efficiently as they could be.

proto3 extend message

Required Is Forever You should be very careful about marking fields as required. If at some point you wish to stop writing or sending a required field, it will be problematic to change the field to an optional field — old readers will consider messages without this field to be incomplete and may reject or drop them unintentionally. You should consider writing application-specific custom validation routines for your buffers instead.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Already on GitHub? Sign in to your account. Spec 3 doesn't mention extend unlike Spec 2. TeBoring unfortunately protobuf compiler protoc accepts this option. And I'm writing Rust implementation of protobuf, and my implementation should be compatible with protoc.

If this option is not meant to be used outside of Google, then public version of protoc compiler should probably reject it. In proto3, custom options are allowed, i. The spec is missing stuff because it was created after protoc, i. If you are implementing protobuf support in a new language it's better to follow what protoc accepts instead of what the spec doc says. Skip to content.

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Jump to bottom. Labels documentation. Projects Weekly Fixit. Copy link Quote reply. This comment has been minimized. Sign in to view. Only MessageOption, which is internal. Don't use it by yourself. TeBoring closed this May 14, TeBoring reopened this May 14, TeBoring assigned anandolee May 14, TeBoring added the documentation label May 14, Support extend definition Sign up for free to join this conversation on GitHub.

Already have an account? Sign in to comment. Weekly Fixit.Recently we extended the Datadog Agent to support extracting additional metrics from Kubernetes using the kube-state-metrics service. Metrics are exported through an HTTP API that supports content negotiation so that one can choose between having the response body in plain text format or as a binary stream encoded using Protocol buffers.

Binary formats are generally assumed to be faster and more efficient, but being Datadog we wanted to see the data and quantify the improvement. We hope the results documented here will help save you time and improve performance in your own code. Protocol Buffers is a way to serialize structured data into a binary stream in a fast and efficient manner. It is designed to be used for inter-machine communication and remote procedure calls RPC.

proto3 extend message

We could simply print out metric values in plain text with a known encoding, using some sort of field separator and a newline character to delimit every entry, something we can implement with a simple format.

With Protocol buffers instead we need to save a text file we can name it metric. Messages in the real world can be way more complex but for the scope of the article we will try to keep things simple. You can dive deeper browsing the official docs, namely the language definition and the Python tutorial. As we mentioned, the.

A tool called protoc standing for Protocol buffers compiler is provided along with the libraries exactly for this purpose: given a. The code above writes the protobuf stream on a binary file on disk. To read the data back to Python all we need to do is this:. We need a way to delimit each message during the serialization process, so that processes at the other end of the wire can determine which chunk of data contains a single Protocol buffer message: at that point, the decoding part is trivial as we have ve already seen.

The documentation suggests prepending the message with its size to ease parsing, but the python implementation does not provide any built in methods for doing this. The Java implementation however offers methods such as parseDelimitedFrom and writeDelimitedTo which make this process much simpler.

This is also the way kube-state-metrics API chains multiple messages. This is quite easy to achieve, except that the Java implementation keeps the size of the message in a Varint value.

Varints are a serialization method that stores integers in one or more bytes: the smaller the value, the fewer bytes you need.

Even if the concept is quite simple, the implementation in Python is not trivial but stay with me, there is good news coming. Protobuf messages are not self-delimited but some of the message fields are. The idea is always the same: fields are preceded by a Varint containing their size. That means that somewhere in the Python library there must be some code that reads and writes Varints - that is what the google. This is clearly not intended to be used outside the package itself, but it seemed useful, so I used it anyway.

The code to serialize a stream of messages would be like:. To read back the data we need to take into account the delimiter and the size.

To keep things simple, just read the entire buffer in memory and process the messages:. At this point you may wondering why bother with Protocol buffers if we need to introduce a compiler and write Python hacks to do something useful with that. There are a number of reasons why people need to serialize data: sending messages between two processes in the same machine, sending them across the internet, or both - all of these use cases imply a very different set of requirements.

Protocol buffers are clever and efficient but some optimizations and perks provided by the format are more visible when applied to certain data formats, or in certains environments: whether this is the right tool or not, that should be decided on a case by case basis.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. In official docs I've found info about how to assign value to a single Any type value, however in my case I have repeated Any field type. Edit : Task. A single Target message is just for minimal reproducible example.

Thanks Justin Schoen. I have limited knowledge of the any type, but I would think it could be treated as if it were a repeated list of Target messages. After playing around some time I have decided to revise the solution that uses repeating Any.

And here is an advice for those who got stuck in this same place: try to use specific types instead of Any. The Task proto file would look like:. Learn more. Ask Question. Asked 10 months ago. Active 5 months ago. Viewed 1k times.

Protocol Buffer Basics: C#

Prisacari Dmitrii. Prisacari Dmitrii Prisacari Dmitrii 10 10 silver badges 18 18 bronze badges. Active Oldest Votes. Pack Target task. Matthew Park Matthew Park 1 1 gold badge 9 9 silver badges 12 12 bronze badges. Justin Schoen Justin Schoen 22 3 3 bronze badges. Simple test gives error: TypeError: Parameter to MergeFrom must be instance of same class: expected google. It looks like you need to initialize your Any array, and then use the pack method to add items to it.

Sign up or log in Sign up using Google. Sign up using Facebook.Welcome to the developer documentation for protocol buffers — a language-neutral, platform-neutral, extensible way of serializing structured data for use in communications protocols, data storage, and more. This overview introduces protocol buffers and tells you what you need to do to get started — you can then go on to follow the tutorials or delve deeper into protocol buffer encoding.

API reference documentation is also provided for all three languages, as well as language and style guides for writing. What are protocol buffers?

Protocol buffers are a flexible, efficient, automated mechanism for serializing structured data — think XML, but smaller, faster, and simpler.

You define how you want your data to be structured once, then you can use special generated source code to easily write and read your structured data to and from a variety of data streams and using a variety of languages. You can even update your data structure without breaking deployed programs that are compiled against the "old" format.

How do they work? You specify how you want the information you're serializing to be structured by defining protocol buffer message types in. Each protocol buffer message is a small logical record of information, containing a series of name-value pairs.

Here's a very basic example of a. You can specify optional fields, required fieldsand repeated fields. You can find more information about writing. Once you've defined your messages, you run the protocol buffer compiler for your application's language on your. You can then use this class in your application to populate, serialize, and retrieve Person protocol buffer messages. You might then write some code like this: Person person; person.

So if you have a communications protocol that uses protocol buffers as its data format, you can extend your protocol without having to worry about breaking existing code.

You'll find a complete reference for using generated protocol buffer code in the API Reference sectionand you can find out more about how protocol buffer messages are encoded in Protocol Buffer Encoding. Why not just use XML? Protocol buffers have many advantages over XML for serializing structured data. Protocol buffers: are simpler are 3 to 10 times smaller are 20 to times faster are less ambiguous generate data access classes that are easier to use programmatically For example, let's say you want to model a person with a name and an email.

The XML version is at least 69 bytes if you remove whitespace, and would take around 5, nanoseconds to parse. HTMLsince you cannot easily interleave structure with text. In addition, XML is human-readable and human-editable; protocol buffers, at least in their native format, are not. XML is also — to some extent — self-describing.

A protocol buffer is only meaningful if you have the message definition the. Sounds like the solution for me! How do I get started? Once you're all set, try following the tutorial for your chosen language — this will step you through creating a simple application that uses protocol buffers.

Introducing proto3 Our most recent version 3 release introduces a new language version - Protocol Buffers language version 3 aka proto3as well as some new features in our existing language version aka proto2. More languages are in the pipeline.

Note that the two language version APIs are not completely compatible. To avoid inconvenience to existing users, we will continue to support the previous language version in new protocol buffers releases. You can see the major differences from the current default version in the release notes and learn about proto3 syntax in the Proto3 Language Guide.

Full documentation for proto3 is coming soon! If the names proto2 and proto3 seem a little confusing, it's because when we originally open-sourced protocol buffers it was actually Google's second version of the language — also known as proto2. This is also why our open source version number started from v2.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Already on GitHub? Sign in to your account. What version of protobuf and what language are you using? Version: v3. Make sure you include information that can help us debug full error message, exception listing, stack trace, logs.

Can you double check that. Or protobuf with Python 3. Sorry about the confusion. I do have SInt32 message defined and I will verify and confirm if that is causing the problem or not. What surprises me is different results in python 3. It is an issue if python 3. We may need more info to identify the reason.

Let me know after you verified message SInt If I change the above message, it works fine. I will see on my end if I am doing something wrong, but could you also double check if the generator is getting confused with the name of message and making wrong assumptions? On python36 it works fine, but on python37 I get error I mentioned earlier.

Note that this also repros if i use 3. So definitely something to do with recent changes in python3. But hope that helps for further investigation on your end. I tried on python2. I believe it is a bug in protobuf and not related with python3. Will try to see and fix the error. Thanks to provide the details to reproduce.

I can make a fix for it but need to take some time because such changes may breaks some of our internal users. Use alias may solve it but not sure it worth to do so. I am marking it as P3 as there are workaround. Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

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