WebService – MEP(信息交换模式)
【1】MEP简介
MEP是Message Exchange Patterns的缩写，意思是”信息交换模式”。
消息交换模式（Message Exchange Pattern：MEP）在SOA中是一个重要的概念。MEP定义了参与者进行消息交换的模板，这是一个很抽象的定义。实际上我们可以这样理解MEP：消息交换模式（MEP）代表一系列的模板，它们定义了消息的发送者和接收者相互进行消息传输的次序。消息交换模式包括：数据报模式（Datagram）、请求/回复模式（Request/Reply）和双工模式（Duplex）。
在Axis2中使用不同的MEP来处理不同的信息交换格式。
【2】MEP具体分类
Axis2目前提供了如下8个MEP，具体体现在org.apache.axis2.description.WSDL2Constants接口中。
MEP_URI_IN_ONLY = "http://www.w3.org/ns/wsdl/in-only"; MEP_URI_ROBUST_IN_ONLY = "http://www.w3.org/ns/wsdl/robust-in-only"; MEP_URI_IN_OUT = "http://www.w3.org/ns/wsdl/in-out"; MEP_URI_IN_OPTIONAL_OUT = "http://www.w3.org/ns/wsdl/in-opt-out"; MEP_URI_OUT_ONLY = "http://www.w3.org/ns/wsdl/out-only"; MEP_URI_ROBUST_OUT_ONLY = "http://www.w3.org/ns/wsdl/robust-out-only"; MEP_URI_OUT_IN = "http://www.w3.org/ns/wsdl/out-in"; MEP_URI_OUT_OPTIONAL_IN = "http://www.w3.org/ns/wsdl/out-opt-in";
WSDL2Constants接口类如下：
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package org.apache.axis2.description; public interface WSDL2Constants { String WSDL_NAMESPACE = "http://www.w3.org/ns/wsdl"; String DEFAULT_WSDL_NAMESPACE_PREFIX = "wsdl2"; String DESCRIPTION = "description"; String URI_WSDL2_SOAP = "http://www.w3.org/ns/wsdl/soap"; String URI_WSDL2_HTTP = "http://www.w3.org/ns/wsdl/http"; String URI_WSDL2_EXTENSIONS = "http://www.w3.org/ns/wsdl-extensions"; String URI_WSDL2_RPC = "http://www.w3.org/ns/wsdl/rpc"; String SOAP_PREFIX = "wsoap"; String HTTP_PREFIX = "whttp"; String WSDL_EXTENTION_PREFIX = "wsdlx"; String WSDL_RPC_PREFIX = "wrpc"; String SOAP_ENV_PREFIX = "soap"; String DEFAULT_TARGET_NAMESPACE_PREFIX = "axis2"; String DOCUMENTATION = "documentation"; String DEFAULT_SOAP11_ENDPOINT_NAME = "SOAP11Endpoint"; String DEFAULT_SOAP12_ENDPOINT_NAME = "SOAP12Endpoint"; String DEFAULT_HTTP_ENDPOINT_NAME = "HTTPEndpoint"; String DEFAULT_HTTPS_PREFIX = "Secure"; String DEFAULT_INTERFACE_NAME = "ServiceInterface"; String TYPES_LOCAL_NALE = "types"; String INTERFACE_LOCAL_NAME = "interface"; String INTERFACE_PREFIX = "Interface"; String OPERATION_LOCAL_NAME = "operation"; String ATTRIBUTE_NAME = "name"; String TARGET_NAMESPACE= "targetNamespace"; String ATTRIBUTE_REF = "ref"; String ATTRIBUTE_LOCATION = "location"; String ATTRIBUTE_CONTENT_ENCODING_DEFAULT = "contentEncodingDefault"; String ATTRIBUTE_CONTENT_ENCODING = "contentEncoding"; String ATTRIBUTE_QUERY_PARAMETER_SEPERATOR = "queryParameterSeparator"; String ATTRIBUTE_QUERY_PARAMETER_SEPERATOR_DEFAULT = "queryParameterSeparatorDefault"; String ATTRIBUTE_ACTION = "action"; String ATTRIBUTE_MEP = "mep"; String ATTRIBUTE_MEP_DEFAULT = "mepDefault"; String ATTRIBUTE_METHOD = "method"; String ATTRIBUTE_METHOD_DEFAULT = "methodDefault"; String ATTRIBUTE_MODULE = "module"; String ATTRIBUTE_IGNORE_UNCITED = "ignoreUncited"; String ATTRIBUTE_INPUT_SERIALIZATION = "inputSerialization"; String ATTRIBUTE_OUTPUT_SERIALIZATION = "outputSerialization"; String ATTRIBUTE_FAULT_SERIALIZATION = "faultSerialization"; String ATTRIBUTE_CODE = "code"; String ATTRIBUTE_SUBCODES = "subcodes"; String ATTRIBUTE_HEADER = "header"; String ATTRIBUTE_TYPE = "type"; String ATTRIBUTE_REQUIRED = "required"; String ATTRIBUTE_MUST_UNDERSTAND = "mustUnderstand"; String ATTRIBUTE_VERSION = "version"; String ATTRIBUTE_PROTOCOL = "protocol"; String ATTRIBUTE_SAFE = "safe"; String ATTRIBUTE_ADDRESS = "address"; String ATTRIBUTE_AUTHENTICATION_TYPE = "authenticationType"; String ATTRIBUTE_AUTHENTICATION_REALM = "authenticationRealm"; String ATTRIBUTE_STYLE = "style"; String ATTRIBUTE_SIGNATURE = "signature"; String OPERATION_STYLE = "operationStyle"; String IN_PUT_LOCAL_NAME = "input"; String OUT_PUT_LOCAL_NAME = "output"; String OUT_FAULT_LOCAL_NAME = "outfault"; String IN_FAULT_LOCAL_NAME = "infault"; String FAULT_LOCAL_NAME = "fault"; String ATTRIBUTE_NAME_PATTERN = "pattern"; String MESSAGE_LABEL = "messageLabel"; String ATTRIBUTE_ELEMENT = "element"; String BINDING_LOCAL_NAME = "binding"; String ENDPOINT_LOCAL_NAME = "endpoint"; String SOAP_BINDING_PREFIX = "SOAPBinding"; String HTTP_PROTOCAL = "http://www.w3.org/2003/05/soap/bindings/HTTP"; String SERVICE_LOCAL_NAME = "service"; String URI_WSOAP_MEP = "http://www.w3.org/2003/05/soap/mep/soap-response/"; String ATTR_WSOAP_PROTOCOL = "wsoap:protocol"; String ATTR_WSOAP_VERSION = "wsoap:version"; String ATTR_WSOAP_CODE = "wsoap:code"; String ATTR_WSOAP_MEP = "wsoap:mep"; String ATTR_WSOAP_MODULE = "wsoap:module"; String ATTR_WSOAP_SUBCODES = "wsoap:subcodes"; String ATTR_WSOAP_HEADER = "wsoap:header"; String ATTR_WSOAP_ACTION = "wsoap:action"; String ATTR_WSOAP_ADDRESS = "wsoap:address"; String ATTR_WHTTP_CONTENT_ENCODING = "whttp:contentEncoding"; String ATTR_WHTTP_LOCATION = "whttp:location"; String ATTR_WHTTP_HEADER = "whttp:header"; String ATTR_WHTTP_METHOD = "whttp:method"; String ATTR_WHTTP_METHOD_DEFAULT = "whttp:methodDefault"; String ATTR_WHTTP_CODE = "whttp:code"; String ATTR_WHTTP_QUERY_PARAMETER_SEPARATOR = "whttp:queryParameterSeparator"; String ATTR_WHTTP_IGNORE_UNCITED = "whttp:ignoreUncited"; String ATTR_WHTTP_INPUT_SERIALIZATION = "whttp:inputSerialization"; String ATTR_WHTTP_OUTPUT_SERIALIZATION = "whttp:outputSerialization"; String ATTR_WHTTP_FAULT_SERIALIZATION = "whttp:faultSerialization"; String ATTR_WHTTP_AUTHENTICATION_TYPE = "whttp:authenticationType"; String ATTR_WHTTP_AUTHENTICATION_REALM = "whttp:authenticationRealm"; String ATTR_WSDLX_SAFE = "wsdlx:safe"; String ATTR_WRPC_SIGNATURE = "wrpc:signature"; String SOAP_VERSION_1_1 = "1.1"; String SOAP_VERSION_1_2 = "1.2"; String MESSAGE_LABEL_IN = "In"; String MESSAGE_LABEL_OUT = "Out"; String RPC_IN = "#in"; String RPC_RETURN = "#return"; String RPC_INOUT = "#inout"; String HTTP_LOCATION_TABLE = "HTTPLocationTable"; // This was taken from thye resolution of CR117 (WSDL 2.0 working group) // http://www.w3.org/2002/ws/desc/5/cr-issues/issues.html?view=normal#CR117 // http://lists.w3.org/Archives/Public/www-ws-desc/2007Feb/0039.html String LEGAL_CHARACTERS_IN_URL = "-._~!$&()*+,;=:@?/%"; String LEGAL_CHARACTERS_IN_PATH = "-._~!$'()*+,;=:@"; String LEGAL_CHARACTERS_IN_QUERY = "-._~!$'()*+,;=:@/?"; String TEMPLATE_ENCODE_ESCAPING_CHARACTER = "!"; public String MEP_URI_IN_ONLY = "http://www.w3.org/ns/wsdl/in-only"; public String MEP_URI_ROBUST_IN_ONLY = "http://www.w3.org/ns/wsdl/robust-in-only"; public String MEP_URI_IN_OUT = "http://www.w3.org/ns/wsdl/in-out"; public String MEP_URI_IN_OPTIONAL_OUT = "http://www.w3.org/ns/wsdl/in-opt-out"; public String MEP_URI_OUT_ONLY = "http://www.w3.org/ns/wsdl/out-only"; public String MEP_URI_ROBUST_OUT_ONLY = "http://www.w3.org/ns/wsdl/robust-out-only"; public String MEP_URI_OUT_IN = "http://www.w3.org/ns/wsdl/out-in"; public String MEP_URI_OUT_OPTIONAL_IN = "http://www.w3.org/ns/wsdl/out-opt-in"; public String STYLE_IRI = "http://www.w3.org/ns/wsdl/style/iri"; public String STYLE_RPC = "http://www.w3.org/ns/wsdl/style/rpc"; public String STYLE_MULTIPART = "http://www.w3.org/ns/wsdl/style/multipart"; public String NMTOKEN_ANY = "#any"; public String NMTOKEN_NONE = "#none"; public String NMTOKEN_OTHER = "#other"; public String NMTOKEN_ELEMENT = "#element"; }
【3】MEP在Axis2-services.xml中使用
AxisSpringService myServiceImpl org.apache.axis2.extensions.spring.receivers.SpringServletContextObjectSupplier
第一个MEP表示有返回值的webservice方法，第二个表示没有返回值。
通过messageReceiver 元素可以配置全局的mep和局部的mep。全局的mep可以通过messageReceivers元素配置，其下可以有多个messageReceiver 子元素。
全局配置如下：
除此之外还可以使用operation元素为某个webservice方法单独指定mep，如上面例子中就是该种方式。
如果为webservice指定了不正确的mep，客户端在调用该方法时会抛出异常。
通常建议在项目中使用全局配置，这样不用为每个方法单独进行配置。
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