Content Management Guide

Chapter 4 Using WebDAV Clients with Director for Collaborative Authoring

This chapter describes the Director WebDAV subsystem, which provides support for the Web Distributed Authoring and Versioning (WebDAV) communications protocol. Using this protocol, the WebDAV subsystem allows you to access server-side content in the Director Content Management subsystem from third-party or custom WebDAV client applications.

This chapter includes the following topics:

What is WebDAV?

The WebDAV protocol extends the Hypertext Transfer Protocol (HTTP) to support asynchronous collaborative authoring on the Web.

As the standard protocol that allows Web browsers to communicate with Web servers, HTTP has transformed the Web into a readable medium by allowing users to view and download individual static documents as read-only information. However, HTTP falls short of supporting write operations such as simultaneous editing of multiple resources on the Web.

WebDAV goes the next step by providing extensions to HTTP that create a distributed writable Web environment. Using WebDAV, multiple users can create content locally or remotely using WebDAV-enabled authoring tools, then save content directly to an URL on an HTTP server.

This section provides a brief overview of WebDAV. For more detailed information, search on the Web for rfc2518—the WebDAV specification. The following URLs provided helpful information at the time this chapter was published:

Information elements for distributed Web authoring

The WebDAV protocol provides methods that act on Web resources, collections, and properties—key information elements used in distributed Web authoring:

Element	Definition	Examples
Resource	Any piece of information that is stored on a Web server and whose location is described by an URL	Web pages, documents, and bitmap images
Collection	A resource that serves as a container for other resources, including other collections. Collections provide a paradigm for grouping and searching resources	Folders and directories
Property (metadata)	Descriptive information that is associated with Web resources but not stored as part of their content	Author, title, publication date, and expiration date

WebDAV extensions to HTTP

The WebDAV protocol provides extensions to HTTP through a set of open standards that can be used by any distributed authoring tool. These extensions support the following key requirements for collaborative authoring on the Web:

Authoring requirement	How WebDAV meets the requirement
Overwrite protection	Mediates concurrent access to content by multiple authors by providing resource locking for write operations
Properties	Provides methods for creating, modifying, reading, and deleting properties
Namespace manipulation	Supports copying and moving multiple Web resources by manipulating names and directories within the namespaces of URLs
Collections	Provides methods for creating and deleting collections, adding members to a collection, removing members from a collection, and listing members of a collection
Version management	Supports the storage of resource revisions for later retrieval. Automatic versioning records successive modifications to a resource
Access control	Limits the access rights of a particular authenticated principal to a given resource

About Director's WebDAV support

The WebDAV subsystem is designed to work with any WebDAV-compliant client application.

When you install the Director WebDAV subsystem, you can create content in your preferred WebDAV-compliant authoring tool and still take advantage of the standard document management capabilities of the Director Content Management subsystem on your server—functions such as checkin, checkout, and versioning.

While most third-party WebDAV clients support these standard document management functions, they do not support the more sophisticated features of the Content Management subsystem, such as categorization and document creation using custom templates. To bridge this gap, the WebDAV subsystem also includes a WebDAV client API that provides classes and methods for accessing these custom features from your own client applications.

For more information about the WebDAV client API, see Building Your Own WebDAV Client.

What you can do with the Director WebDAV subsystem

You will be able to perform the following functions remotely from your WebDAV client application:

Save your content in the content repository
Get the latest version of your content from the content repository for editing
Lock content for editing in the content repository and know that your changes will not be overwritten by another author
Unlock content so that it is available to other authors for editing
Copy and move content across collections within the hierarchical physical infrastructure of the content repository
Delete content from the content repository
Make new collections in the content repository
Retrieve resources and collections from the server
Upload resources and collections from the client to the server

WebDAV-enabled clients implement these functions in different ways. Consult your client documentation to learn how to use specific third-party tools with the WebDAV protocol.

For more information about the WebDAV methods Director supports, see Supported methods.

How Director stores content from WebDAV clients

When you save content created using a third-party WebDAV client to the Director content repository, the content is stored as a system resource. The repository handles system resources by storing a default set of properties (or metadata) along with content. The following table describes these properties and how default values are assigned:

Property	Default value
Name	Name of file (with extension if provided) NOTE Some WebDAV clients require you to specify extensions for files to indicate the appropriate content editor
Author	Identifier of user who is logged in
Date created	Date uploaded
Abstract	None
Publish date	Null, which means publish as soon as possible
Expiration date	Null, which means never expire
Checked out by	None

You can change or assign values to these properties in the Director Content Management subsystem programmatically or using the Portal Management Console (PMC). Some WebDAV-enabled authoring tools also allow you to edit property values on the client side.

For more information about using the PMC, see Portal Management Console.

When content is stored as a system resource, it cannot be associated with any custom document types or categories that have been defined in the Content Management subsystem. To create content that is more tightly integrated with these Content Management subsystem features, you can:

Build your own WebDAV client application using a client API provided with the Director WebDAV subsystem

For more information about the WebDAV client API, see Building Your Own WebDAV Client.
Use the Content Management API or the PMC to create a document of a particular type in the Content Management subsystem on the server. You can then edit this content inside a WebDAV-compliant client, preserving the original document type.

How Director secures content from WebDAV clients

The Director WebDAV subsystem requires you to provide a valid user ID and password to the WebDAV client. These values are used to authenticate your access privileges when you attempt to access secure content in the content repository from your WebDAV client.

Users do not see resources for which they do not have read access.

For more information, see Setting up the client.

How Director manages versioning for WebDAV clients

When a WebDAV client requests a resource from the server, the WebDAV subsystem returns the latest version from the content repository—though not necessarily the published version. For example, a WebDAV client cannot retrieve the published version of content if it is not the latest version.

When the WebDAV client uploads and checks in a resource, the WebDAV subsystem creates a new version and publishes it in the content repository.

Installing the Director WebDAV subsystem

You install the WebDAV subsystem when you create a project in eXtend Workbench using the Director EAR Wizard. If you have not created a Director EAR project that includes the WebDAV subsystem, follow the procedure in this section. If you have, you are ready to deploy the WebDAV subsystem and can skip to Deploying the Director WebDAV subsystem below the procedure.

To install the WebDAV subsystem:

Make sure you have installed the prerequisite SilverStream products: eXtend Workbench and eXtend Director.

For information about how to install eXtend Workbench, see the Release Notes in the SilverStream eXtend Workbench help.

For information about how to install eXtend Director, see the Director Release Notes (in this online help).
Follow the instructions for creating a new Director EAR project in the chapter on configuring and deploying Director applications in the Core Development Guide.
NOTE During this process, you choose between two setup options: Typical and Custom. If you select Typical Setup, the WebDAV subsystem is installed automatically as part of the Director EAR using WebDAVService as the service context root and main as the servlet path. If you opt for Custom Setup, you must include the WebDAV subsystem explicitly and can specify a service context root and servlet path.
After creating the EAR project, select Archive Layout and look for WebDAVService.war.
Expand WebDAVService.war, navigate to WEB-INF/lib, and double-click WebDAVService.jar to view the WebDAV subsystem classes you have just installed in your Director EAR project.

Now you are ready to deploy the WebDAV subsystem to your J2EE application server.

Deploying the Director WebDAV subsystem

You deploy the WebDAV subsystem by deploying the EAR in which it resides.

Before you deploy

Before deploying the Director WebDAV subsystem, you must install the following software:

A J2EE application server
A WebDAV-enabled client authoring tool

If you are deploying to the SilverStream eXtend Application Server, you must also create a new (empty) database.

For a list of supported application servers and databases, see the Director Release Notes.

How to deploy

To deploy the WebDAV subsystem:

Start your J2EE application server.
If you are deploying to the SilverStream eXtend Application Server, add your new (empty) database to the server.
Follow the instructions for deploying a Director EAR project in the chapter on configuring and deploying Director applications in the Core Development Guide.

Setting up the client

After you deploy the WebDAV subsystem, you can connect a WebDAV-enabled client to the Director content repository. To establish this connection, you must provide the following parameters to the client:

User ID and password that are valid for Director (not a server user ID and password)
URL that references the directory on the WebDAV server you want to connect to

The structure of the URL for the SilverStream WebDAV server is:
```
  http://server name/database name/EAR namespace/service context root/servlet path/
```
The structure of the URL for WebLogic or WebSphere WebDAV servers is:
```
  http://server name/EAR namespace/service context root/servlet path/
```
For example, if your SilverStream server is localhost, database name is Director, EAR namespace is DirectorEAR, service context root is WebDAVService, and servlet path is main, the URL should look like this:
```
  http://localhost/Director/DirectorEAR/WebDAVService/main/
```

Consult client documentation to learn how to provide these parameters and connect to a site—in this case, the Director content repository—using the WebDAV protocol.

Supported methods

The Director WebDAV subsystem supports the following WebDAV methods. Consult client documentation to learn how to perform these functions from your WebDAV-enabled authoring tool.

Method	Description
PROPFIND	Retrieves properties on resources and collections from the server. Generally, this action is transparent to the user; WebDAV client tools use this method to get and display properties such as name, type (of resource), date modified, and checked out by.
PROPPATCH	Sets and/or removes properties on server-side resources and collections identified by the Request-URI. Generally, this action is transparent to the user; WebDAV client tools use this method to modify properties such as name, type (of resource), date modified, and checked out by.
COPY	Copies resources and collections on the server—along with their properties—without causing name conflicts. When you copy a collection, all of its members are also copied.
DELETE	Deletes resources or collections on the server.
GET	Retrieves resources and collections from the server, as identified by the Request-URI. Some WebDAV-enabled clients automatically check out resources for you before downloading them from the server; other clients require you to perform two separate operations—first check out the resource, then get it.
HEAD	Like GET, but retrieves only header information without a response message body.
LOCK	Creates a lock specified by the lockinfo XML element on the Request-URI. The lockinfo element specifies the scope, type, and owner of the lock. The Director Content Management subsystem uses just one type of lock—the exclusive lock, to enforce pessimistic concurrency. The scope of a lock spans the entire state of the resource, including its body and associated properties. Some WebDAV-enabled clients automatically lock resources before you check them out; other clients require you to explicitly lock a resource as a separate operation.
UNLOCK	Removes the lock identified in the Lock-Token request header of the Request-URI. This action unlocks all resources included in the lock. Some WebDAV-enabled clients automatically unlock resources after you check them in; other clients require you to explicitly unlock a resource as a separate operation.
MKCOL	Creates collections on the server.
MOVE	Moves resources and collections on the server without creating name conflicts.
PUT	Uploads resources and collections from the client to the server.
OPTIONS	Returns all methods that can be called on resources and collections specified in the Request-URI. For example, if the resource is a document, OPTIONS returns LOCK, UNLOCK, OPTIONS, GET, PUT, MOVE, DELETE, COPY, PROPFIND, and PROPPATCH.

Content Management Guide