What is a message based web service

Demis Bellot edited this page Oct 25, 2016 · 3 revisions

This page has moved to docs.servicestack.net

Answer from ServiceStack's interview on InfoQ:

In essence, a message-based service is one that passes messages to facilitate its communication. A good metaphor for illustrating the differences between a RPC method and a message-based API can be seen in Smalltalk or Objective-C's message dispatch mechanism vs a normal static C method call. Method invocations are coupled to instance they are invoked on, in a message-based system the request is captured in the message and sent to a receiver. The receiver doesn't have to handle the message as it can optionally delegate the request to an alternative receiver to process instead.

Message-based design in ServiceStack

Message-based design is enabled in ServiceStack by capturing the Services Request Query into a Request DTO that's completely de-coupled from any one implementation. You can think of making a ServiceStack request as a Smalltalk runtime method dispatch at a Macro scale, where the ServiceStack host is the Receiver, the HTTP Verb is the selector and Request DTO is the message.

It doesn't matter on which of the endpoints the Request is sent to as the request can be populated with any combination of PathInfo, QueryString and Request Body. After the Request binding, the request travels through all user-defined filters and pre-processors for inspection where it can optionally be handled before it is able to reach the service implementation. Once the request reaches the service it invokes the best matching selector, by default it will look for a method with the same name as a HTTP Verb, if it doesn't exist it falls back to using a catch-all 'Any' method that can be used to handle the request on any endpoint or route in any format. Even when inside the Service implementation it is able to further delegate the request to an alternative service or easily proxy the request to a remote sharded instance if it needs to.

Conceptually in ServiceStack you're just sending a message to a ServiceStack instance, the client is not concerned with what ultimately handles it, only that a response is returned for reply requests or that the request is successfully accepted for oneway messages. In a RPC API you're conceptually invoking a remote method which has the request tightly coupled to its remote implementation method signature.

Benefits of adopting a Message-based design

There are many natural benefits gained when adopting a message-based design they offer better resilience, flexibility, versionability then their RPC cousins. An example of one of the benefits possible is when you send a request to its one-way endpoint, if the ServiceStack instance has a MQ Host configured, the request is automatically deferred to the configured MQ Broker and processed in the background. So even if the ServiceStack Host goes down none of the pending messages are lost and are automatically processed the next time the Host starts up. This is the type of behavior that is enabled for free in ServiceStack. When no MQ host is enabled the request is just processed normally, i.e. synchronously by a HTTP web worker.

Most of the benefits of message-based designs are gained over time as you're developing and evolving your existing services and adding support for more clients. One immediate benefit is being able to provide an end-to-end typed API without the use of code-gen. This is impossible to achieve without a message-based design which ensures the essence of your Service Contract is captured in re-usable DTOs. Being able to share your server DTOs you defined your web services with on the client completely by-pass the normal development workflow required in re-generating your clients proxies from your services interim WSDL/XSD schemas.

Typed, Native SDK's provide maximum end-user value

Typed clients are the under-pinnings for Native SDK's which provide the most value to end-users of your service as they reduce the most of the burden required in order to consume your API. This approach is popular for companies that really, really want you to use their APIs, i.e. where their businesses success depends on its popular use. This is the preferred approach taken by Amazon EC2, Google App Engine, Azure, Facebook, Ebay, Stripe, Braintree, etc.

More importantly, message-based designs encourage the design of coarse-grained and more re-usable services. By contrast RPC method signatures are generally designed to serve a single-purpose, i.e. Rather than adding more RPC methods for every client requirement (which introduces a new external endpoint each time), message-based designs instead encourages enhancing existing services with extra functionality since they can be added without friction. This additionally has the benefit of providing instant utility to existing clients already consuming existing services, since they can easily access the extra features without introducing a new code-path to call a new external endpoint.

Ideal for SOA

This is an especially important approach to take whenever implementing service-intensive systems like SOA platforms, as services routinely end up out-living and serving more clients that the original client that consume them, so it's important not to have your service APIs driven by adhoc client-specific requirements. It's more useful to think about designing APIs from the system's perspective with the goal of exposing the underlying systems capabilities in a generically re-usable API. This is the main reason why I now only ever adopt message-based designs for all my services endpoints as Coarse-grained APIs naturally encourage the design of more re-usable and feature-rich APIs.

Adopted by most leading distributed frameworks

Benefits of message-based designs are already well-known to developers of leading distributed frameworks who have adopted message-based designs in leading platforms, e.g: Google's Protocol Buffers, Amazon's Web Services platform, Erlang processes, F# mailboxes, Scala's Actors, Go's Channels, Dart's Isolates and Clojure's agents, etc.

  1. Getting Started

    1. Creating your first project
    2. Create Service from scratch
    3. Your first webservice explained
    4. Example Projects Overview
    5. Learning Resources
  2. Designing APIs

    1. ServiceStack API Design
    2. Designing a REST-ful service with ServiceStack
    3. Simple Customer REST Example
    4. How to design a Message-Based API
    5. Software complexity and role of DTOs
  3. Reference

    1. Order of Operations
    2. The IoC container
    3. Configuration and AppSettings
    4. Metadata page
    5. Rest, SOAP & default endpoints
    6. SOAP support
    7. Routing
    8. Service return types
    9. Customize HTTP Responses
    10. Customize JSON Responses
    11. Plugins
    12. Validation
    13. Error Handling
    14. Security
    15. Debugging
    16. JavaScript Client Library (ss-utils.js)
  4. Clients

    1. Overview
    2. C#/.NET client
      1. .NET Core Clients
    3. Add ServiceStack Reference
      1. C# Add Reference
      2. F# Add Reference
      3. VB.NET Add Reference
      4. Swift Add Reference
      5. Java Add Reference
    4. Silverlight client
    5. JavaScript client
      1. Add TypeScript Reference
    6. Dart Client
    7. MQ Clients
  5. Formats

    1. Overview
    2. JSON/JSV and XML
    3. HTML5 Report Format
    4. CSV Format
    5. MessagePack Format
    6. ProtoBuf Format
  6. View Engines 4. Razor & Markdown Razor

    1. Markdown Razor
  7. Hosts

    1. IIS
    2. Self-hosting
    3. Messaging
    4. Mono
  8. Security

    1. Authentication
    2. Sessions
    3. Restricting Services
    4. Encrypted Messaging
  9. Advanced

    1. Configuration options
    2. Access HTTP specific features in services
    3. Logging
    4. Serialization/deserialization
    5. Request/response filters
    6. Filter attributes
    7. Concurrency Model
    8. Built-in profiling
    9. Form Hijacking Prevention
    10. Auto-Mapping
    11. HTTP Utils
    12. Dump Utils
    13. Virtual File System
    14. Config API
    15. Physical Project Structure
    16. Modularizing Services
    17. MVC Integration
    18. ServiceStack Integration
    19. Embedded Native Desktop Apps
    20. Auto Batched Requests
    21. Versioning
    22. Multitenancy
  10. Caching

  11. Caching Providers

  12. HTTP Caching

  13. CacheResponse Attribute

  14. Cache Aware Clients

  15. Auto Query

  16. Overview

  17. Why Not OData

  18. AutoQuery RDBMS

  19. AutoQuery Data

  20. AutoQuery Memory

  21. AutoQuery Service

  22. AutoQuery DynamoDB

  23. Server Events

    1. Overview
    2. JavaScript Client
    3. C# Server Events Client
    4. Redis Server Events
  24. Service Gateway

    1. Overview
    2. Service Discovery
  25. Encrypted Messaging

    1. Overview
    2. Encrypted Client
  26. Plugins

    1. Auto Query
    2. Server Sent Events
    3. Swagger API
    4. Postman
    5. Request logger
    6. Sitemaps
    7. Cancellable Requests
    8. CorsFeature
  27. Tests

    1. Testing
    2. HowTo write unit/integration tests
  28. ServiceStackVS

    1. Install ServiceStackVS
    2. Add ServiceStack Reference
    3. TypeScript React Template
    4. React, Redux Chat App
    5. AngularJS App Template
    6. React Desktop Apps
  29. Other Languages

    1. FSharp
      1. Add ServiceStack Reference
    2. VB.NET
      1. Add ServiceStack Reference
    3. Swift
    4. Swift Add Reference
    5. Java
      1. Add ServiceStack Reference
      2. Android Studio & IntelliJ
      3. Eclipse
  30. Amazon Web Services

  31. ServiceStack.Aws

  32. PocoDynamo

  33. AWS Live Demos

  34. Getting Started with AWS

  35. Deployment

    1. Deploy Multiple Sites to single AWS Instance
      1. Simple Deployments to AWS with WebDeploy
    2. Advanced Deployments with OctopusDeploy
  36. Install 3rd Party Products

    1. Redis on Windows
    2. RabbitMQ on Windows
  37. Use Cases

    1. Single Page Apps
    2. HTML, CSS and JS Minifiers
    3. Azure
    4. Connecting to Azure Redis via SSL
    5. Logging
    6. Bundling and Minification
    7. NHibernate
  38. Performance

    1. Real world performance
  39. Other Products

    1. ServiceStack.Redis
    2. ServiceStack.OrmLite
    3. ServiceStack.Text
  40. Future

    1. Roadmap
Clone this wiki locally
You can’t perform that action at this time.
You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. Reload to refresh your session.
Press h to open a hovercard with more details.