| <!-- |
| ~ 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. |
| --> |
| |
| <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" |
| "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> |
| <html xmlns="http://www.w3.org/1999/xhtml" version="-//W3C//DTDXHTML1.1//EN"> |
| <head> |
| <meta http-equiv="content-type" content=""/> |
| <title>HTTP transports</title> |
| </head> |
| |
| <body lang="en"> |
| <a name="configTransport"></a> |
| |
| <h1>HTTP Transport</h1> |
| |
| <p>This document covers the sending and receiving of SOAP messages with Axis2 using HTTP |
| as the transport mechanism.</p> |
| |
| <h2>Contents</h2> |
| <ul> |
| <li><a href="#HTTPClient4TransportSender">HTTPClient4TransportSender</a> |
| <ul> |
| <li><a href="#httpsupport">HTTPS support</a></li> |
| </ul> |
| </li> |
| <li><a href="#timeout_config">Timeout Configuration</a></li> |
| <li><a href="#version_config">HTTP Version Configuration</a></li> |
| <li><a href="#auth">Proxy Authentication</a></li> |
| <li><a href="#preemptive_auth">Basic, Digest and NTLM Authentication</a></li> |
| <li><a href="#reusing_httpclient_object">Reusing the httpclient object</a></li> |
| <li><a href="#setting_cached_httpclient_object">Setting the cached httpclient object</a></li> |
| </ul> |
| <a name="HTTPClient4TransportSender"></a> |
| |
| <h2>HTTPClient4TransportSender</h2> |
| |
| <p>HTTPClient4TransportSender is the transport sender that is used by default in both |
| the Server and Client APIs. As its name implies, it is based on <a |
| xmlns="http://www.w3.org/1999/xhtml" xml:space="preserve" href="http://hc.apache.org/">Apache HttpComponents</a>. |
| For maximum flexibility, this sender supports both the HTTP GET and POST interfaces. |
| (REST in Axis2 also supports both interfaces.)</p> |
| |
| <p>Axis2 uses a single HTTPClient instance per ConfigurationContext (which usually means per instance |
| of ServiceClient). This pattern allows for HTTP 1.1 to automatically reuse TCP connections - in earlier versions of Axis2 the REUSE_HTTP_CLIENT configuration property was necessary to enable this functionality, but as of 1.5 this is no longer necessary.</p> |
| |
| <p>Apache HttpComponents also provides HTTP 1.1, Chunking and KeepAlive support for Axis2.</p> |
| |
| |
| <p>The <transportSender/> element defines transport senders in |
| the axis2.xml configuration file as follows:</p> |
| <pre> |
| <transportSender name="http" class="org.apache.axis2.transport.http.impl.httpclient4.HTTPClient4TransportSender"> |
| <parameter name="PROTOCOL">HTTP/1.1</parameter> |
| <parameter name="Transfer-Encoding">chunked</parameter> |
| </transportSender> |
| </pre> |
| |
| <p>The above code snippet shows the simplest configuration of a transport |
| sender for common use. The <parameter/> element is used to specify additional |
| constraints that the sender should comply with. The HTTP PROTOCOL parameter |
| should be set as HTTP/1.0 or HTTP/1.1. The default version is HTTP/1.1. Note that |
| chunking support is available only for HTTP/1.1. Thus, even if "chunked" is specified |
| as a parameter, if the HTTP version is 1.0, this setting will be |
| ignored by the transport framework. Also, KeepAlive is enabled by default in |
| HTTP/1.1.</p> |
| <p>If you use HTTP1.1 for its Keep-Alive ability, but you need to disable |
| chunking at runtime (some servers don't allow chunked requests to |
| prevent denial of service), you can do so in the Stub: |
| </p> |
| |
| <pre> |
| options.setProperty(HTTPConstants.CHUNKED, "false"); |
| </pre> |
| |
| <p>Some absolute properties are provided at runtime instead. For example, character |
| encoding style (UTF-8, UTF-16, etc.) is provided via MessageContext.</p> |
| <a name="httpsupport"></a> |
| |
| <h3>HTTPS support</h3> |
| HTTPClient4TransportSender can be also used to communicate over https. |
| |
| <pre> |
| <transportSender name="<b>https</b>" class="org.apache.axis2.transport.http.impl.httpclient4.HTTPClient4TransportSender"> |
| <parameter name="PROTOCOL">HTTP/1.1</parameter> |
| <parameter name="Transfer-Encoding">chunked</parameter> |
| </transportSender> |
| </pre> |
| |
| <p>Please note that by default HTTPS works only when the server does not |
| expect to authenticate the clients (1-way SSL only) and where the |
| server has the clients' public keys in its trust store. |
| |
| If you want to perform SSL client authentication (2-way SSL), you may |
| use the Protocol.registerProtocol feature of HttpClient. You can |
| overwrite the "https" protocol, or use a different protocol for your |
| SSL client authentication communications if you don't want to mess |
| with regular https. Find more information at |
| <a href="https://hc.apache.org">https://hc.apache.org</a></p> |
| <a name="timeout_config"></a> |
| |
| <h2>Timeout Configuration</h2> |
| |
| <p>Two timeout instances exist in the transport level, Socket timeout |
| and Connection timeout. These can be configured either at deployment |
| or run time. If configuring at deployment time, the user has to add the |
| following lines in axis2.xml.</p> |
| |
| <p>For Socket timeout:</p> |
| <pre><parameter name="SO_TIMEOUT">some_integer_value</parameter></pre> |
| |
| <p>For Connection timeout:</p> |
| <pre> <parameter name="CONNECTION_TIMEOUT">some_integer_value</parameter></pre> |
| <br/> |
| |
| For runtime configuration, it can be set as follows within the client stub: |
| <pre> |
| ... |
| Options options = new Options(); |
| options.setProperty(HTTPConstants.SO_TIMEOUT, new Integer(timeOutInMilliSeconds)); |
| options.setProperty(HTTPConstants.CONNECTION_TIMEOUT, new Integer(timeOutInMilliSeconds)); |
| |
| // or |
| options.setTimeOutInMilliSeconds(timeOutInMilliSeconds); |
| ... |
| </pre> |
| |
| <a name="version_config"></a> |
| |
| <h2>HTTP Version Configuration</h2> |
| |
| <p>The default HTTP version is 1.1. There are two methods in which the user |
| can change the HTTP version to 1.0</p> |
| <ul> |
| <li>By defining the version in axis2.xml as shown below. |
| <pre> <parameter name="PROTOCOL">HTTP/1.0</parameter></pre></li> |
| <li>By changing the version at runtime by using code similar to the following: |
| <pre> |
| ... |
| options.setProperty(org.apache.axis2.context.MessageContextConstants.HTTP_PROTOCOL_VERSION, |
| org.apache.axis2.transport.http.HTTPConstants.HEADER_PROTOCOL_10); |
| ... |
| </pre></li> |
| </ul> |
| <a name="auth"></a> |
| |
| <h2>Proxy Authentication</h2> |
| |
| <p>The Apache Httpcomponents client has built-in support for proxy |
| authentication. Axis2 uses deployment time and runtime mechanisms to |
| authenticate proxies. At deployment time, the user has to change the |
| axis2.xml as follows. This authentication is available for both HTTP and |
| HTTPS.</p> |
| <pre> |
| <transportSender name="<b>http</b>" class="org.apache.axis2.transport.http.impl.httpclient4.HTTPClient4TransportSender"> |
| <parameter name="PROTOCOL">HTTP/1.1</parameter> |
| <parameter name="PROXY" proxy_host="proxy_host_name" proxy_port="proxy_host_port">userName:domain:passWord</parameter> |
| </transportSender></pre> |
| |
| <p>For a particular proxy, if authentication is not available, enter the |
| "userName:domain:passWord" as "anonymous:anonymous:anonymous".</p> |
| |
| <p>Prior shown configuration has been deprecated after Axis2 1.2 release and we strongly recommend using the new |
| proxy configuration as below. </p> |
| <p> |
| New proxy configuration would require the user to add a TOP level parameter in the axis2.xml named "Proxy". |
| </p> |
| <pre> |
| <parameter name="Proxy"> |
| <Configuration> |
| <ProxyHost>example.org</ProxyHost> |
| <ProxyPort>5678</ProxyPort> |
| <ProxyUser>EXAMPLE\saminda</ProxyUser> |
| <ProxyPassword>ppp</ProxyPassword> |
| </Configuration> |
| </parameter> |
| </pre> |
| |
| <p> Thus, if its a open proxy, user can ignore ProxyUser and ProxyPassword elements. </p> |
| |
| <p>In addition to this, if you don't want to go through writing the above parameter you could |
| use Java Networking Properties for open proxies, |
| -Dhttp.proxyHost=10.150.112.254 -Dhttp.proxyPort=8080 </p> |
| |
| <p>At runtime, the user can override the PROXY settings using the |
| HttpTransportProperties.ProxyProperties object. Within your client stub, |
| create an instance of this object, configure proxy values for it, |
| and then set it to the MessageContext's property bag via options.setProperty(). |
| For example:</p> |
| <pre> |
| ... |
| Options options = new Options(); |
| ... |
| |
| HttpTransportProperties.ProxyProperties proxyProperties = new HttpTransportProperties.new ProxyProperties(); |
| proxyProperties.setProxyHostName(....); |
| proxyProperties.setProxyPort(...); |
| ... |
| options.setProperty(HttpConstants.PROXY, proxyProperties); |
| ... |
| </pre> |
| <p>The above code will override the deployment proxy configuration settings.</p> |
| <a name="preemptive_auth"></a> |
| |
| <h2>Basic, Digest and NTLM Authentication</h2> |
| |
| <p>HttpClient supports three different types of HTTP authentication schemes: |
| Basic, Digest and NTLM. Based on the challenge provided by the server, |
| HttpClient automatically selects the authentication scheme with which the |
| request should be authenticated. The most secure method is NTLM and the Basic |
| is the least secure.</p> |
| |
| <p>NTLM is the most complex of the authentication protocols supported by |
| HttpClient. It requires an instance of NTCredentials to be available for the |
| domain name of the server or the default credentials. Note that since NTLM |
| does not use the notion of realms, HttpClient uses the domain name of the |
| server as the name of the realm. Also note that the username provided to the |
| NTCredentials should not be prefixed with the domain - ie: "axis2" is correct |
| whereas "DOMAIN\axis2" is not correct.</p> |
| |
| <p>There are some significant differences in the way that NTLM works compared |
| with basic and digest authentication. These differences are generally handled |
| by HttpClient, however having an understanding of these differences can help |
| avoid problems when using NTLM authentication.</p> |
| <ol> |
| <li>NTLM authentication works almost exactly the same way as any other form |
| of authentication in terms of the HttpClient API. The only difference is |
| that you need to supply 'NTCredentials' instead of |
| 'UsernamePasswordCredentials' (NTCredentials actually extends |
| UsernamePasswordCredentials so you can use NTCredentials right throughout |
| your application if need be).</li> |
| <li>The realm for NTLM authentication is the domain name of the computer to |
| which you are being connected. This can become troublesome as servers often |
| have multiple domain names that refer to them. Only the domain name that |
| the HttpClient connects to (as specified by the HostConfiguration) is |
| used to look up the credentials. It is generally advised that while |
| initially testing NTLM authentication, you pass the realm as null, which |
| is its default value.</li> |
| <li>NTLM authenticates a connection and not a request. So you need to |
| authenticate every time a new connection is made, and keeping the |
| connection open during authentication is vital. Because of this, NTLM cannot |
| be used to authenticate with both a proxy and the server, nor can NTLM be |
| used with HTTP 1.0 connections or servers that do not support HTTP |
| keep-alives.</li> |
| </ol> |
| |
| <p>Axis2 also allows adding a custom Authentication Scheme to HttpClient.</p> |
| |
| <p>The static inner bean Authenticator of HttpTransportProperties will hold |
| the state of the server to be authenticated with. Once filled, it has to be |
| set to the Options's property bag with the key as HTTPConstants.AUTHENTICATE. |
| The following code snippet shows how to configure the transport |
| framework to use Basic Authentication:</p> |
| <pre> |
| ... |
| Options options = new Options(); |
| |
| HttpTransportProperties.Authenticator |
| auth = new HttpTransportProperties.Authenticator(); |
| auth.setUsername("username"); |
| auth.setPassword("password"); |
| // set if realm or domain is known |
| |
| options.setProperty(org.apache.axis2.transport.http.HTTPConstants.AUTHENTICATE, auth); |
| ... |
| </pre> |
| <a name="reusing_httpclient_object"></a> |
| <h2>Reusing the httpclient object</h2> |
| |
| <p>By default, a new httpclient object is created for each send. It may |
| be worthwhile to reuse the same httpclient object to take advantage of |
| HTTP1.1 Keep-Alive, especially in HTTPS environment, where the SSL |
| handshake may not be of negligible cost. To reuse the same httpclient |
| object, you can set the relevant property in the Stub: |
| </p> |
| |
| <pre>options.setProperty(HTTPConstants.REUSE_HTTP_CLIENT, "true");</pre> |
| |
| <a name="setting_cached_httpclient_object"></a> |
| <h2>Setting the cached httpclient object</h2> |
| |
| To control the max connections per host attempted in parallel by a |
| reused httpclient (this can be worthwhile as the default value is 2 |
| connections per host), or any other advanced parameters, you need to |
| set the cached httpclient object when your application starts up |
| (before any actual axis request). You can set the relevant property in |
| the Stub: |
| |
| <pre> |
| MultiThreadedHttpConnectionManager conmgr = new MultiThreadedHttpConnectionManager(); |
| conmgr.getParams().setDefaultMaxConnectionsPerHost(10); |
| HttpClient client = new HttpClient(conmgr); |
| configurationContext.setProperty(HTTPConstants.CACHED_HTTP_CLIENT, client); |
| </pre> |
| |
| <a name="setting_cached_httpstate_object"></a> |
| <h2>Setting the cached httpstate object</h2> |
| |
| HttpState object can be set as property to the options of a given Axis2 client. |
| HttpState keeps HTTP attributes that may persist from request to request, such |
| as cookies and authentication credentials. So, it is possible to re-use one and |
| the same HttpState object if appropriate. |
| |
| The idea is to provide the capability to specify/associate a separate HttpState |
| with every client and still reuse one and the same HttpClient. So, this make |
| sense only when CACHED_HTTP_CLIENT is re-used between different clients |
| from different threads which may invoke different hosts with different credentials |
| and cookies. This is really complicated scenario, but is absolutely possible one. |
| If you re-use a common HttpClient between different clients then the clients will |
| re-use, the internal for the HttpClient, HttpState object. Doing so authentication |
| credentials are exposed to all clients sharing one and the same HttpClient. |
| This is definitely not a good idea. The problem with Cookies is different. The |
| problem here is that if two distinct clients invoke one and the same service |
| at a specific host then the session established with a given cookie by one of |
| the clients can wrongly be shared among them, too, if it has not expired. This |
| will cause problems since the two client may need different sessions, which is |
| the more probable scenario. |
| |
| Sample configuration: |
| |
| <pre> |
| HttpState myHttpState = new HttpState(); |
| options.setProperty(WSClientConstants.CACHED_HTTP_STATE, myHttpState); |
| </pre> |
| |
| Doing so the HttpState is attached to the client. Respectively this is automatically propagated to all MessageContext objects used by the client. |
| Underneath this just instructs Axis2 that the CACHED_HTTP_STATE set should be passed as a parameter when HttpClient#executeMethod is invoked. |
| |
| </body> |
| </html> |
