book

Twisted Network Programming Essentials, 2nd Edition

by Abe Fettig, Jessica McKellar

March 2013

Beginner

191 pages

4h 9m

English

O'Reilly Media, Inc.

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Why Use Twisted?What This Book CoversConventions Used in This BookWhat You’ll NeedChanges Since the Previous EditionUsing Code ExamplesSafari® Books OnlineHow to Contact UsAcknowledgments
Installing TwistedInstallation on LinuxMore package options and optional dependenciesInstallation on WindowsOptional dependenciesAdding Twisted utilities to your PATHInstallation on OS XOptional dependenciesInstalling from SourceRequired DependenciesInstalling a C compilerInstalling zope.interfaceInstalling Twisted from a Release TarballInstalling Twisted from a Source CheckoutInstalling Optional Dependencies from SourceTesting Your InstallationUsing the Twisted DocumentationAPI DocumentationSubproject DocumentationFinding Answers to Your QuestionsMailing ListsIRC ChannelsStack OverflowTwisted Blogs
A TCP Echo Server and ClientEvent-Driven ProgrammingThe ReactorTransportsProtocolsProtocol FactoriesDecoupling Transports and ProtocolsA TCP Quote Server and ClientProtocol State MachinesMore Practice and Next Steps
What Deferreds Do and Don’t DoThe Structure of a Deferred ObjectCallback Chains and Using Deferreds in the ReactorPractice: What Do These Deferred Chains Do?Exercise 1Exercise 2Exercise 3Exercise 4Exercise 5Exercise 6The Truth About addCallbacksExercise 7Exercise 8Key Facts About DeferredsSummary of the Deferred APIMore Practice and Next Steps
Responding to HTTP Requests: A Low-Level ReviewThe Structure of an HTTP RequestParsing HTTP RequestsHandling GET RequestsServing Static ContentStatic URL dispatchServing Dynamic ContentDynamic DispatchCreating resources that are both renderable and have childrenRedirectsHandling POST RequestsA Minimal POST ExampleAsynchronous ResponsesMore Practice and Next Steps
Basic HTTP Resource RetrievalPrinting a Web ResourceDownloading a Web ResourceAgentRequesting Resources with AgentRetrieving Response MetadataPOSTing Data with AgentMore Practice and Next Steps
The Twisted Application InfrastructureServicesApplicationsTAC FilestwistdPluginsMore twistd ExamplesMore Practice and Next StepsSuggested Exercises

Basic In-Application Loggingtwistd LoggingCustom LoggersKey Facts and Caveats About Logging
Nonblocking Database QueriesMore Practice and Next Steps
The Components of Twisted CredTwisted Cred: An ExampleCredentials CheckersAuthentication in Twisted ApplicationsMore Practice and Next Steps
ThreadsSubprocessesRunning a Subprocess and Getting the ResultCustom Process ProtocolsMore Practice and Next Steps
Writing and Running Twisted Unit Tests with TrialTesting ProtocolsTests and the ReactorTesting DeferredsTesting the Passage of TimeMore Practice and Next Steps
IRC ClientsIRC ServersMore Practice and Next Steps
SMTP Clients and ServersThe SMTP ProtocolSending Emails Using SMTPSMTP ServersStoring MailIMAP Clients and ServersIMAP ServersIMAP ClientsPOP3 Clients and ServersPOP3 ServersMore Practice and Next Steps
SSH ServersA Basic SSH ServerUsing Public Keys for AuthenticationProviding an Administrative Python ShellRunning Commands on a Remote ServerSSH ClientsMore Practice and Next Steps
Contributing to Twisted

Content preview from Twisted Network Programming Essentials, 2nd Edition

Chapter 4. Web Servers

This chapter will first extend our experience with writing basic TCP servers to the construction of basic HTTP servers. With that context and understanding of the HTTP protocol in hand, we’ll then abandon the low-level API in favor of the high-level twisted.web APIs used for constructing sophisticated web servers.

Note

Twisted Web is the Twisted subproject focusing on HTTP communication. It has robust HTTP 1.1 and HTTPS client and server implementations, proxy support, WSGI integration, basic HTML templating, and more.

Responding to HTTP Requests: A Low-Level Review

The HyperText Transfer Protocol (HTTP) is a request/response application-layer protocol, where requests are initiated by a client to a server, which responds with the requested resource. It is text-based and newline-delimited, and thus easy for humans to read.

To experiment with the HTTP protocol we’ll create a subclass of protocol.Protocol, the same class we used to build our echo servers and clients in Chapter 2. Our protocol will know how to accept a connection, process the request, and send back an HTTP-formatted response.

This section is intended as both a glimpse under the hood and a refresher on the HTTP protocol. When building real web servers, you’ll almost certainly use the higher-level twisted.web APIs Twisted provides. If you’d prefer to skip to that content, head over to Handling GET Requests.