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Python / XML-RPC

Python / XML-RPC

  • 20.23. xmlrpclib — XML-RPC client access — Python 2.7.16 documentation #ril

    • The xmlrpclib module has been renamed to xmlrpc.client in Python 3. The 2to3 tool will automatically adapt imports when converting your sources to Python 3.

    • XML-RPC is a Remote Procedure Call method that uses XML passed via HTTP(S) as a transport. With it, a client can call methods WITH PARAMETERS on a remote server (the server is named by a URI) and get back STRUCTURED DATA.

      Changed in version 2.7.9: For HTTPS URIs, xmlrpclib now performs all the necessary CERTIFICATE AND HOSTNAME CHECKS by default.

    • This module supports writing XML-RPC client code; it handles all the details of TRANSLATING between conformable Python objects and XML on the wire.

      The xmlrpclib module is not secure against maliciously constructed data. If you need to parse untrusted or unauthenticated data see XML vulnerabilities.

      自動把 ODM (Object Document Mapping) 做掉了；因為會自動解析/轉換 XML response 的關係，有可能遭到攻擊。

  • xmlrpc — XMLRPC server and client modules — Python 3.7.3 documentation #ril

  • xmlrpc.client — XML-RPC client access — Python 3.7.2 documentation #ril

新手上路 {: #getting-started }

  • Example of Client Usage - 20.23. xmlrpclib — XML-RPC client access — Python 2.7.16 documentation

    # simple test program (from the XML-RPC specification)
from xmlrpclib import ServerProxy, Error

# server = ServerProxy("http://localhost:8000") # local server
server = ServerProxy("http://betty.userland.com")

print server

try:
    print server.examples.getStateName(41)
except Error as v:
    print "ERROR", v

    透過 ServerProxy 跟 XML-RPC server 溝通，範例 .examples.getStateName(41) 中的 getStateName(41) 是 method 與 parameters，那 examples 是什麼 ??

ServerProxy

  • class xmlrpclib.ServerProxy - 20.23. xmlrpclib — XML-RPC client access — Python 2.7.16 documentation

    class xmlrpclib.ServerProxy(uri[, transport[, encoding[, verbose[, allow_none[, use_datetime[, context]]]]]])

    • A ServerProxy instance is an object that manages communication with a remote XML-RPC server. The required first argument is a URI (Uniform Resource Indicator), and will normally be the URL of the server.

      Server is retained as an alias for ServerProxy for backwards compatibility. New code should use ServerProxy.

    • The optional second argument is a TRANSPORT FACTORY instance; by default it is an internal SafeTransport instance for https: URLs and an internal HTTP Transport instance otherwise.

      The optional third argument is an encoding, by default UTF-8. The optional fourth argument is a debugging flag.

    • The following parameters govern the use of the RETURNED PROXY INSTANCE. If allow_none is true, the Python constant None will be translated into XML; the default behaviour is for None to raise a TypeError. This is a commonly-used extension to the XML-RPC specification, but isn’t supported by all clients and servers; see http://ontosys.com/xml-rpc/extensions.php for a description.

      allow_none 是控制 Python --> XML-RPC 的轉換，預設 None 會丟出 TypeError，好奇 None 在 XML 裡會怎麼表現 ??

      The use_datetime flag can be used to cause date/time values to be presented as datetime.datetime objects; this is false by default. datetime.datetime objects may be passed to calls.

      搭配 "to be presented as" 與 "may be passed to calls" 的說法，呼叫時一定可以傳 datetime.datetime，use_datetime 是在控制 XML-RPC --> Python 的轉換。

    • Both the HTTP and HTTPS transports support the URL syntax extension for HTTP Basic Authentication: http://user:pass@host:port/path. The user:pass portion will be BASE64-ENCODED as an HTTP ‘Authorization’ header, and sent to the remote server as part of the connection process when invoking an XML-RPC method. You only need to use this if the remote server requires a Basic Authentication user and password.

      不用自己做 Base64 編碼，寫成 user:pass 內部會自動處理編碼。

      If an HTTPS URL is provided, context may be ssl.SSLContext and configures the SSL settings of the underlying HTTPS connection.

      只能用這種方式驗證身份嗎 ??

    • The returned instance is a PROXY OBJECT with methods that can be used to invoke corresponding RPC calls on the remote server.

      ServerProxy 名副其實是個 proxy object !!

    • Changed in version 2.5: The use_datetime flag was added.

    • Changed in version 2.6: Instances of new-style classes can be passed in if they have an __dict__ attribute and don’t have a base class that is marshalled in a special way.

    • Changed in version 2.7.9: Added the context argument.

  • ServerProxy Objects - 20.23. xmlrpclib — XML-RPC client access — Python 2.7.16 documentation #ril

    • A ServerProxy instance has a method corresponding to each remote procedure call accepted by the XML-RPC server. Calling the method performs an RPC, dispatched by both name and argument signature (e.g. the same method name can be OVERLOADED with multiple argument signatures).

      The RPC finishes by returning a value, which may be either returned data in a conformant type or a Fault or ProtocolError object indicating an error.

Data Type

  • class xmlrpclib.ServerProxy - 20.23. xmlrpclib — XML-RPC client access — Python 2.7.16 documentation

    • Types that are conformable (e.g. that can be MARSHALLED through XML), include the following (and except where noted, they are UNMARSHALLED as the same Python type):

      XML-RPC type -> Python type

      • boolean -> bool

      • int / i4 --> int or long in range from -2147483648 to 2147483647.

      • double -> float

      • string -> str or unicode

      • array -> list or tuple containing conformable elements. Arrays are returned as lists.

      • struct -> dict.

        Keys must be strings, values may be any conformable type. Objects of user-defined classes can be passed in; only their __dict__ attribute is transmitted.

      • dateTime.iso8601 -> xmlrpclib.DateTime or datetime.datetime. Returned type depends on values of the use_datetime flags.

        預設傳回 xmlrpclib.DateTime，啟用 use_datetime 才會傳回 datetime.datetime；但有什麼理由不用 datetime.datetime ??

      • base64 -> xmlrpclib.Binary

        為什麼不是 str (Python 2) 或 bytes (Python 3)? 會跟 string -> str/unicode 混淆 ??

      • nil -> The None constant. Passing is allowed only if allow_none is true.

        若 XML-RPC 有 nil 的概念，為什麼傳入 None 要特別用 allow_none 控制，而且預設還沒開啟 ??

    • Note that even though starting with Python 2.2 you can subclass built-in types, the xmlrpclib module currently does not marshal instances of such subclasses. ??

      這跟上面的一段說明有關：

      Changed in version 2.6: Instances of new-style classes can be passed in if they have an __dict__ attribute and don’t have a base class that is marshalled in a special way.

    • When passing strings, characters special to XML such as <, >, and & will be AUTOMATICALLY ESCAPED. However, it’s the caller’s responsibility to ensure that the string is free of characters that aren’t allowed in XML, such as the CONTROL CHARACTERS with ASCII values between 0 and 31 (except, of course, tab, newline and carriage return); failing to do this will result in an XML-RPC request that ISN’T WELL-FORMED XML.

      If you have to pass arbitrary strings via XML-RPC, use the Binary wrapper class described below.

  • Boolean Objects - 20.23. xmlrpclib — XML-RPC client access — Python 2.7.16 documentation #ril

  • DateTime Objects - 20.23. xmlrpclib — XML-RPC client access — Python 2.7.16 documentation #ril

  • Binary Objects - 20.23. xmlrpclib — XML-RPC client access — Python 2.7.16 documentation #ril

Error Handling

Instrospection API

參考資料 {: #reference }

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