Deploying an Application

WebStack provides a number of potentially useful modules either providing resource classes for direct use in applications, or providing other kinds of classes and functions which may be used to perform particular -activities.

WebStack also provides modules which provide session-like access to different kinds of repositories:

FileResource - Serving Individual Files

The FileResource class provides a means to +serve individual static files from the +filesystem. Although a DirectoryResource +object may serve files having specific filename extensions as +particular types from a filesystem directory, we sometimes need to +select individual files from special locations and serve their +contents as part of a response.

WebStack API - FileResource Initialisation

The FileResource class (found in the WebStack.Resources.Static module) accepts the following parameters when being initialised:

filename: The full path to the particular static file being served.
content_type: A content type object (such as WebStack.Generic.ContentType) providing sufficient information for user agents to interpret the file's contents.

Combining MapResource with FileResource

One might combine MapResource with FileResource to provide a favicon.ico image for an application as follows:

In the above example, the favicon.ico file in the images directory is served as image/x-icon.

Viewing the API Documentation

Supported Frameworks

With the help of Python's built-in +standard library, WebStack can run without any additional software, but +you may wish to investigate the other supported frameworks in order to +run WebStack applications in other environments.

Viewing the API Documentation

The API documentation for use in conjunction with this guide can be found inside the apidocs directory within the WebStack-1.2 directory. Of course, @@ -34,4 +37,4 @@

About WebStack Applications

LoginRedirect and Login Modules

Introducing LoginRedirectResource

The easiest way of introducing LoginRedirectResource objects -is to do so in the adapter code, as described in "Writing Adapters". The most +is to do so in the adapter code, as described in "Writing Adapters". The most significant difference between deploying normal resources and LoginRedirectResource objects is the special way in which @@ -195,5 +192,4 @@ out. A special logout confirmation URL may also be configured (see logout_url and use_logout_redirect above).

Path Info Support in Server Environments

The following table summarises the support for "path info" within applications amongst the supported server environments or frameworks within WebStack:

Framework	CGI	Path beyond resource (correct)
Django	Path beyond context (correct)
Java Servlet API	Path beyond context (correct)

Paths To and + Paths To and Within Applications + +

Paths +To and Within Applications

One thing to be aware of, in the code of an application, is which part of a -path refers to the location of the application in a server environment, and +path refers to the location of the application in a server environment, +and which refers to some resource within the application itself. Consider this path:

Let us say +that the application was deployed in a Zope server instance inside @@ -25,48 +23,50 @@ We may then say that the path to the application is this: -

In WebStack, we +refer to this latter case - the path within +the application - as the "path info".

WebStack API - Paths To +
WebStack API - Paths To Resources Within Applications

On transaction objects, the following methods exist to inspect paths to resources within applications.
-
-
`get_path_info`
-
This gets the path of a +

`get_path_info`
+
This gets the path of a resource within an application. The path should always contain a leading `/` character at the very least.
-An optional `encoding` parameter may be used to assist the process of converting the path to a Unicode object - see "Character Encodings" for more information.
-
`get_virtual_path_info`
-
This gets the path of a +An optional `encoding` parameter may be +used to assist the process of converting the path to a Unicode object - +see "Character Encodings" +for more information.

`get_virtual_path_info`
+
This gets the path of a resource within a part of an application - the application itself decides the scope of the path and can set the "virtual path info" using the `set_virtual_path_info` method. The path should either contain a leading `/` character optionally followed by other characters, or an empty string.
- -An optional `encoding` parameter may be used to assist the process of converting the path to a Unicode object - see "Character Encodings" for more information.
`get_processed_virtual_path_info`
-
This gets the virtual path information which is considered to +An optional `encoding` parameter may be +used to assist the process of converting the path to a Unicode object - +see "Character Encodings" +for more information.
`get_processed_virtual_path_info`
+
This gets the virtual path information which is considered to have been processed or traversed, and consists of the part of the path info which does not appear in the virtual path info. In other words, when components at the start of the virtual path info are removed, such components will appear at the end of the processed virtual path info.
- -An optional `encoding` parameter may be used to assist the process of converting the path to a Unicode object - see "Character Encodings" for more information.
- -
-
-

Choosing the Right Path Value

Given that the path may change depending on where an +An optional encoding parameter may be +used to assist the process of converting the path to a Unicode object - +see "Character Encodings" +for more information. +

Choosing the Right Path Value

Given that the path may change depending on +where an application is deployed in a server environment, it may not be very easy to use when determining which resources are being requested or accessed within your application. Conversely, given that the "path @@ -74,33 +74,27 @@ it may be difficult to use that to provide references or links to those resources. Here is a summary of how you might use the different path values:

Using the Virtual +Path

Although WebStack sets the "path info" so that +applications +know which part of themselves are being accessed, you may +decide that upon processing the request, these different parts of your application should be @@ -112,19 +106,22 @@ part they used, passing on a modified path to the other resources. For such approaches, the "virtual path info" may be used instead, since it permits modification within an application.

So starting with a virtual path like this (which would be the +same as the "path info")...

Then, +having processed the first non-empty part (remembering that the first part will be an empty string)...

...it will reconstruct the path, removing the processed part (but -remembering to preserve a leading / character)...

...it +will reconstruct the path, removing the processed part (but +remembering to preserve a leading / +character)...

...and +hand over control to another resource which would do the same thing with the first of the other path components (department and employee), and so on.

The compelling thing about this strategy is the way that each @@ -133,17 +130,46 @@ independently from any "parent" resource. Moreover, such resources could be deployed independently and still operate in the same way without being "hardcoded" into assuming that they always reside at a -particular level in a resource hierarchy.

+particular level in a resource hierarchy.

WebStack API - Paths To Resources Within Applications

On transaction objects, the following method exists to set virtual paths within applications.

set_virtual_path_info

This sets the virtual path, affecting subsequent calls to the get_virtual_path_info +

set_virtual_path_info: This +sets the virtual path, affecting subsequent calls to the get_virtual_path_info method. The path should either contain a leading / -character optionally followed by other characters, or an empty string.

+character optionally followed by other characters, or an empty string. +

Summary

The following illustration hopefully provides a more memorable way of representing the structure of paths:

Supported Frameworks

URL
Protocol, host, port	Path
Path without query		Query
Path without path info	Path info
Processed virtual path info	Virtual path info
http://www.python.org	/folder/application	/resource	/operation	?	a=1&b=2

Framework	Versions Tested	Availability	Also Required
BaseHTTPRequestHandler	Python 2.2.2 Python 2.3.3 Python 2.4.1	Found in Python's standard library - no additional software required
CGI	Apache 2.0.44 Apache 2.0.53 AOLserver 4.0.10 lighttpd 1.3.15		Web server with CGI support: Apache httpd (http://httpd.apache.org/) AOLserver (http://aolserver.com/) lighttpd (http://www.lighttpd.net/)
Django	Django 0.95	http://www.djangoproject.com/
Jython/Java Servlet	Jython 2.1, Java JDK 1.3.1_02, Tomcat 4.1.31 (Servlet 2.3)		Jython (http://www.jython.org/) Java Servlet container: Apache Tomcat (http://tomcat.apache.org/)
mod_python	3.0.3 (3.1.3 for framework cookie and session support)	http://www.modpython.org/	Apache httpd (http://httpd.apache.org/)
Twisted	Twisted 1.0.5 Twisted 1.3.0	http://www.twistedmatrix.com/
Webware	0.8.1 CVS (2004-02-06) 0.9b2	http://www.webwareforpython.org/	Web server supporting CGI (see above)
WSGI	run_with_cgi (PEP 333)		Web server supporting CGI (see above)
Zope 2	2.7.2-0 2.8.0-final	http://www.zope.org/

Each framework has its own set of strengths and weaknesses, but the +idea is that deployment concerns can be considered separately from the +implementation of application functionality.

More Information

See the "Deploying Applications" document for information on exact deployment procedures for each of the above frameworks.

Deploying an Application

Deployment

Deployment

Useful Additions

FileResource - Serving Individual Files

WebStack API - FileResource Initialisation

Combining MapResource with FileResource

Viewing the API Documentation

Supported Frameworks

Viewing the API Documentation

About WebStack Applications

LoginRedirect and Login Modules

Introducing LoginRedirectResource

Path Info Support in Server Environments

Paths To and + Paths To and Within Applications + +

Paths +To and Within Applications

WebStack API - Paths To Resources Within Applications

Choosing the Right Path Value

Choosing the Right Path Value

Using the Virtual Path

Using the Virtual +Path

WebStack API - Paths To Resources Within Applications

Summary

Supported Frameworks

More Information