org.wandora.modules.topicmap

Class ViewTopicAction

java.lang.Object

org.wandora.modules.AbstractModule

org.wandora.modules.ScriptModule

org.wandora.modules.servlet.AbstractAction

org.wandora.modules.servlet.CachedAction

org.wandora.modules.servlet.GenericTemplateAction

org.wandora.modules.topicmap.ViewTopicAction

All Implemented Interfaces:

Module, ActionHandler, ServletModule.RequestListener

Direct Known Subclasses:

ViewTopicWebApp

public class ViewTopicAction
extends GenericTemplateAction

An action for displaying something about a single topic using a template. This extends GenericTemplateAction and adds some features related to topics. For the most part, however, it works exactly like GenericTemplateAction.

The topic this action uses can be specified in the HTTP request. The request parameter used for this is topic, but it can be changed using the initialisation parameter topicRequestKey. The request parameter value can be a number of things. It can be prefixed with one of "si:", "sl:" or "bn:" standing for subject identifier, subject locator and base name, respectively. The prefix is then followed by the value of the chosen identifying field. If you do not use any prefix, a topic is looked for trying all the identifying fields in that order until a topic is found. That is, the value is first assumed to be a subject identifier, then a subject locator and finally a base name. If no suitable topic is found, whether a prefix is used or not, the action will fail.

You may set the initialisation parameter noTopic to true to disable automatic topic resolution. In this case you should resolve the topic in your template. You will also need to forward the relevant request parameter to the template, which is best done using GenericTemplateAction's forwardRequestParameters.

Unless noTopic is set to true, the topic will be automatically added to the template context. By default this is done using template parameter name "topic", but this can be changed using the initialisation parameter topicContextKey. Similarly the topic map is added to the context using parameter name "topicmap" and this can be changed with the initialisation parameter topicMapContextKey. The exact value of the HTTP request parameter is also added in the context with parameter name "topicRequest". This will include the possible prefix of the value, as described above.

You can set the default topic and default language using initialisation parameters defaultTopic and defaultLang, respectively. If either is left undefined in the HTTP request, the defaults will be used instead.

Note that the getTopic and getTopics methods are static and can, and should, be used in other actions which need to resolve topics based on request parameters.

Author:

olli

Nested Class Summary

Nested classes/interfaces inherited from class org.wandora.modules.servlet.CachedAction

CachedAction.OutputProvider

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.String	defaultLang
protected java.lang.String	defaultTopic
protected boolean	noTopic
protected TopicMapManager	tmManager
protected java.lang.String	topicContextKey
protected java.lang.String	topicMapContextKey
protected java.lang.String	topicRequestKey

Fields inherited from class org.wandora.modules.servlet.GenericTemplateAction

defaultRequestParameters, forwardRequestParameters, requestContextKey, staticContext, templateKey, templateManager

Fields inherited from class org.wandora.modules.servlet.CachedAction

cache, caching, threadPool

Fields inherited from class org.wandora.modules.servlet.AbstractAction

actionParamKey, handledActions, httpHeaders, isDefaultAction, replacements, replacementsInitialized, servletModule

Fields inherited from class org.wandora.modules.ScriptModule

engine, initScript, persistentObjects, scriptManager, startScript, stopScript

Fields inherited from class org.wandora.modules.AbstractModule

autoStart, isInitialized, isRunning, logging, loggingModule, moduleManager

Constructor Summary

Constructors

Constructor and Description
ViewTopicAction()

Method Summary

Modifier and Type	Method and Description
protected java.lang.String	getCacheKey(javax.servlet.http.HttpServletRequest req, ModulesServlet.HttpMethod method, java.lang.String action) Should return a string that uniquely identifies this request.
protected java.util.LinkedHashMap<java.lang.String,java.lang.String>	getCacheKeyParams(javax.servlet.http.HttpServletRequest req, ModulesServlet.HttpMethod method, java.lang.String action) Returns the parameters used in building the cache key.
java.util.Collection<Module>	getDependencies(ModuleManager manager) Returns all the modules this module depends on.
protected java.util.HashMap<java.lang.String,java.lang.Object>	getStaticTemplateContext() Gets the static context to for templates.
protected java.util.HashMap<java.lang.String,java.lang.Object>	getTemplateContext(Template template, javax.servlet.http.HttpServletRequest req, ModulesServlet.HttpMethod method, java.lang.String action, User user) Gets the template context used for a request.
static Topic	getTopic(java.lang.String query, TopicMap tm) Same as getTopics, but returns only the first result of what getTopics would return.
static java.util.ArrayList<Topic>	getTopics(java.lang.String query, TopicMap tm, int max) Returns topics based on a simple query.
boolean	handleAction(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp, ModulesServlet.HttpMethod method, java.lang.String action, User user) Handles this action.
void	init(ModuleManager manager, java.util.HashMap<java.lang.String,java.lang.Object> settings) Initialises the module.
void	start(ModuleManager manager) Starts the module.
void	stop(ModuleManager manager) Stops the module.

Methods inherited from class org.wandora.modules.servlet.GenericTemplateAction

doOutput, getForwardedParameters, getTemplate, putStaticContext, returnOutput

Methods inherited from class org.wandora.modules.servlet.CachedAction

buildCacheKey, readMetadata, writeMetadata

Methods inherited from class org.wandora.modules.servlet.AbstractAction

addHandledAction, doReplacements, handleRequest, isHandleAction, setActionParamKey, setHttpHeaders

Methods inherited from class org.wandora.modules.ScriptModule

getScriptEngine

Methods inherited from class org.wandora.modules.AbstractModule

isInitialized, isRunning, requireLogging, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

topicRequestKey

protected java.lang.String topicRequestKey

topicMapContextKey

protected java.lang.String topicMapContextKey

topicContextKey

protected java.lang.String topicContextKey

noTopic

protected boolean noTopic

defaultLang

protected java.lang.String defaultLang

defaultTopic

protected java.lang.String defaultTopic

tmManager

protected TopicMapManager tmManager

Constructor Detail

ViewTopicAction

public ViewTopicAction()

Method Detail

getDependencies

public java.util.Collection<Module> getDependencies(ModuleManager manager)
                                             throws ModuleException

Description copied from interface: Module

Returns all the modules this module depends on. This method will be called after init and the dependencies are allowed to depend on the parameters passed to init. The modules that this module depends on must be returned as a collection. In addition, if any required module is not present, a MissingDependencyException should be thrown. Typically you will use the requireModule and optionalModule methods of the manager to make sure that the modules exist and add them to the collection. requireModule will automatically throw the exception too if the module is not found whereas optionalModule does not.

Specified by:

getDependencies in interface Module

Overrides:

getDependencies in class GenericTemplateAction

Parameters:

manager - The module manager handling this module.

Returns:

A collection of modules this module depends on.

Throws:

ModuleException

init

public void init(ModuleManager manager,
                 java.util.HashMap<java.lang.String,java.lang.Object> settings)
          throws ModuleException

Description copied from interface: Module

Initialises the module. After constructor, this is the first method called in the life cycle of a module. It should not perform anything time consuming or anything with notable outside side effects. It should only read the parameters and initialise the module so that it can later be started. Note that a module being initialised doesn't mean that it necessarily will ever be started.

A ModuleException may be thrown if something vital is missing from the parameters or they are not sensible. In some cases you may not want to throw an exception even if vital initialisation information is missing. If, for example, it is possible that the module is initialised in some other way between the init and the start method calls. A ModuleException may also be thrown at the start method if the module is still not initialised.

Specified by:

init in interface Module

Overrides:

init in class GenericTemplateAction

Parameters:

manager - The module manager handling this module. You may keep a reference to it if needed.

Throws:

ModuleException

start

public void start(ModuleManager manager)
           throws ModuleException

Description copied from interface: Module

Starts the module. This will be called after init and getDependencies and signals that the module should now begin to perform whatever it was designed to do. This method call however should not block for long, so any time consuming tasks should be started in their own threads. You will typically get references to the required modules again in start using the findModule method of the manager and then store those references to instance variables for later use. You may throw a ModuleException if the module is not in a state where it can be started or it immediately becomes obvious that it cannot be started with the provided settings.

Specified by:

start in interface Module

Overrides:

start in class GenericTemplateAction

Parameters:

manager - The module manager handling this module.

Throws:

ModuleException

stop

public void stop(ModuleManager manager)

Description copied from interface: Module

Stops the module. Should stop all threads used by the module, free any large data structures and perform other cleanup. It is possible that the module will be started again later with a start method call (and foregoing init and getDependencies calls). The module should be left in a state where this is possible.

Specified by:

stop in interface Module

Overrides:

stop in class GenericTemplateAction

Parameters:

manager - The module manager handling this module.

getCacheKeyParams

protected java.util.LinkedHashMap<java.lang.String,java.lang.String> getCacheKeyParams(javax.servlet.http.HttpServletRequest req,
                                                                                       ModulesServlet.HttpMethod method,
                                                                                       java.lang.String action)

Description copied from class: GenericTemplateAction

Returns the parameters used in building the cache key. This implementation uses the request action parameter and all parameters that have been configured to be forwarded from the request into the template context.

Overrides:

getCacheKeyParams in class GenericTemplateAction

Parameters:

req - The HTTP request for which cache key parameters are resolved.

method - The method of the HTTP request.

action - The parsed action parameter from the request.

Returns:

getCacheKey

protected java.lang.String getCacheKey(javax.servlet.http.HttpServletRequest req,
                                       ModulesServlet.HttpMethod method,
                                       java.lang.String action)

Description copied from class: CachedAction

Should return a string that uniquely identifies this request. A future request with the same cache key may use the cached copy of the page. If you don't want some requests cached at all, return a null cache key for those pages. You can use the buildCacheKey method to create a cache key out of a map.

Overrides:

getCacheKey in class GenericTemplateAction

Parameters:

req - The HTTP request which, result of which is to be cached.

method - The method of the HTTP request.

action - The parsed action parameter from the request.

Returns:

A cache key that uniquely identifies the results of this request being processed.

getTopics

public static java.util.ArrayList<Topic> getTopics(java.lang.String query,
                                                   TopicMap tm,
                                                   int max)
                                            throws TopicMapException

Returns topics based on a simple query. Currently this will only ever return a single topic at most, in the future more supported query types might be added which could return more topics.

At the moment, the query can be prefixed with one of "si:", "sl:" or "bn:" which stand for subject identifier, subject locator and base name, respectively. After the prefix, add the value of the chosen identifying field. That topic will then be returned, or an empty collection if it doesn't exist. If you don't use any prefix, the value is first assumed to be a subject identifier, if that doesn't correspond to an existing topic, then subject locator is tried, and finally base name. If none work, then an empty collection is returned. Otherwise the first match is returned.

Parameters:

query - The topic query.

tm - The topic map where to execute the query.

max - Maximum number of results to return.

Returns:

The topics matching the query.

Throws:

TopicMapException

getTopic

public static Topic getTopic(java.lang.String query,
                             TopicMap tm)
                      throws TopicMapException

Same as getTopics, but returns only the first result of what getTopics would return. As noted in getTopics documentation, at the moment it will only ever return at most a single topic anyway so there isn't much difference between these two methods yet. This method will return null if no topic is found.

Parameters:

query - The topic query.

tm - The topic map where to execute the query.

Returns:

The first result of the query or null if no topics were found.

Throws:

TopicMapException

getStaticTemplateContext

protected java.util.HashMap<java.lang.String,java.lang.Object> getStaticTemplateContext()

Description copied from class: GenericTemplateAction

Gets the static context to for templates. Includes action specific items added with putStaticContext as well as the template manager default context.

Overrides:

getStaticTemplateContext in class GenericTemplateAction

Returns:

The static template context.

getTemplateContext

protected java.util.HashMap<java.lang.String,java.lang.Object> getTemplateContext(Template template,
                                                                                  javax.servlet.http.HttpServletRequest req,
                                                                                  ModulesServlet.HttpMethod method,
                                                                                  java.lang.String action,
                                                                                  User user)
                                                                           throws ActionException

Description copied from class: GenericTemplateAction

Gets the template context used for a request. Contains the static context as well forwarded request parameters. The static context contains both action specific context items and the template manager default context. In addition, the logged in user, if applicable, is added with the variable name user. Usually you don't want anything user specific cached so as a safety measure, the user variable is not added if caching is turned on. If you for some reason do, you will have to override this method.

This should be the main overriding point for extending classes. You can perform any tasks needed and then add things in the context. Often you don't need to override anything else besides this and the basic Module methods.

Overrides:

getTemplateContext in class GenericTemplateAction

Parameters:

template - The template to be used.

req - The HTTP request.

method - The method of the HTTP request.

action - The action parameter parsed from the HTTP request.

user - The logged in user, or null if not logged in.

Returns:

The template context used with processing the template for this action.

Throws:

ActionException

handleAction

public boolean handleAction(javax.servlet.http.HttpServletRequest req,
                            javax.servlet.http.HttpServletResponse resp,
                            ModulesServlet.HttpMethod method,
                            java.lang.String action,
                            User user)
                     throws javax.servlet.ServletException,
                            java.io.IOException,
                            ActionException

Description copied from class: AbstractAction

Handles this action. Prior to calling this action, it's already been determined that this action should try to handle the action by either matching the action request parameter with the action id of this action, or this being the default action. Perform any operations needed here and then write the response into the response object. You will typically want to call setHttpHeaders to set the HTTP headers in the response after you know that you definitely will handle the request but before you write anything else into the response stream. If for whatever reason this method shouldn't handle the request after all, return false. Otherwise return true.

Overrides:

handleAction in class CachedAction

Parameters:

req - The HTTP Request.

resp - The HTTP response.

method - The HTTP method of the request.

action - The parsed action id.

user - The logged in user, or null if not applicable.

Returns:

True if the action was handled and a response sent. False otherwise in which case other actions may try to handle this action.

Throws:

javax.servlet.ServletException

java.io.IOException

ActionException