Download pdf lwp::useragent

For instance, we will send HTTP::Request s both to ftp and gopher servers, as well as to the local file system. The uri might also encode various other parameters. The main attributes of objects of this class are:. Since we don't want to handle all possible code values directly in our programs, a libwww-perl response object has methods that can be used to query what kind of response this is. The most commonly used response classification methods are:.

The request failed. The server or the resource might not be available, access to the resource might be denied or other things might have failed for some reason. Let us assume that we have created a request object.

What do we actually do with it in order to receive a response? The answer is that you pass it to a user agent object and this object takes care of all the things that need to be done like low-level communication and error handling and returns a response object. The user agent represents your application on the network and provides you with an interface that can accept requests and return responses.

The user agent is an interface layer between your application code and the network. Through this interface you are able to access the various servers on the network. Every libwww-perl application that wants to communicate should create at least one object of this class. The main method provided by this object is request. The user agent has many other attributes that let you configure how it will interact with the network and with your application.

If this is set, then the address will be sent to the servers with every request. Many applications want even more control over how they interact with the network and they get this by sub-classing LWP::UserAgent.

This example shows how the user agent, a request and a response are represented in actual perl code:. New request objects should normally created for each request sent. This section discusses the various protocol schemes and the HTTP style methods that headers may be used for each. For all responses, the library adds a header called "Client-Date". This header holds the time when the response was received by your application.

The format and semantics of the header are the same as the server created "Date" header. You may also encounter other "Client-XXX" headers. They are all generated by the library internally and are not received from the servers.

See lwpcook for examples of this. The library allows you to access proxy server through HTTP. This means that you can set up the library to forward all types of request through the HTTP protocol module. These headers denote the encryption method used and the name of the server owner. The request can contain the header "If-SSL-Cert-Subject" in order to make the request conditional on the content of the server certificate.

If the certificate subject does not match, no request is sent to the server and an internally generated error response is returned. PUT stores a file on a ftp server. You can specify a ftp account for servers that want this in addition to user name and password. This is specified by including an "Account" header in the request.

It also supports transfer of ranges for FTP transfers using the "Range" header. The File::Listing module provides methods for parsing of these directory listing. The so called Basic access authentication is a very simple way to limit access to certain web pages. Web servers can be configured to protect a given directory, or a whole site by a few lines of configuration.

How can we write a script using LWP::UserAgent that will authenticate with such server and will be able to access the protected pages? If you click on Login , you'll see a "challenge", a pop-up that, depending on your browser, might look like this: If you cancel it, you'll see and Authorization Required error. If you type in incorrect credentials it will show you the pop-up again and again till you get tired of it.

Access without authentication In the first version of our script, we just create an LWP::UserAgent object, and use the get method to fetch the page that requires authentication. Either you supplied the wrong credentials e. See realm explained later. The Realm The "realm" is a string, sort of an identification string of the area protected by the basic authentication system. The realm is usually displayed in the challenge pop-up box.

How to find out the URL and realm? The script looked like this: use strict; use warnings; use 5. Our methods does not do much, just prints the received parameters using warn. This is, as this is only a temporary solution while we do our little research. This technique, of reaching inside another name-space and redefining functions there is called Monkey patching.

It is one of the great flexibilities of dynamic languages. I want to automate the process using LWP in perl. Expand Select Wrap Line Numbers. Follow Post Reply. Here is an example of one way to do authentication with the Mech module and in the modules FAQ page , you will find another way. Regards, Jeff. Is it possible to do using LWP module? Regards, N. Post Reply. Similar topics Perl. How to call a web service using NT Authentication. NET Framework.

Proxy Authentication Required using VS Using webproxy object in 2.