Developing Web Applications

Developing Web Applications

This chapter describes how web applications are supported in the Eclipse GlassFish.

The following topics are addressed here:

For general information about web applications, see " The Web Tier" in The Jakarta EE Tutorial.

The Web Profile of the Eclipse GlassFish supports the EJB 3.1 Lite specification, which allows enterprise beans within web applications, among other features. The full Eclipse GlassFish supports the entire EJB 3.1 specification. For details, see JSR 318 (http://jcp.org/en/jsr/detail?id=318).

Using Servlets

Eclipse GlassFish supports the Java Servlet Specification version 4.0.

Servlet API version 4.0 is fully backward compatible with versions 3.0, 2.3, 2.4, and 2.5, so all existing servlets should work without modification or recompilation.

To develop servlets, use the Java Servlet API. For information about using the Java Servlet API, see the documentation at https://jakarta.ee/specifications/servlet/.

The Eclipse GlassFish provides the wscompile and wsdeploy tools to help you implement a web service endpoint as a servlet. For more information about these tools, see the Eclipse GlassFish Reference Manual.

This section describes how to create effective servlets to control application interactions running on a Eclipse GlassFish, including standard-based servlets. In addition, this section describes the Eclipse GlassFish features to use to augment the standards.

The following topics are addressed here:

Caching Servlet Results

The Eclipse GlassFish can cache the results of invoking a servlet, a JSP, or any URL pattern to make subsequent invocations of the same servlet, JSP, or URL pattern faster. The Eclipse GlassFish caches the request results for a specific amount of time. In this way, if another data call occurs, the Eclipse GlassFish can return the cached data instead of performing the operation again. For example, if your servlet returns a stock quote that updates every 5 minutes, you set the cache to expire after 300 seconds.

Whether to cache results and how to cache them depends on the data involved. For example, it makes no sense to cache the results of a quiz submission, because the input to the servlet is different each time. However, it makes sense to cache a high level report showing demographic data taken from quiz results that is updated once an hour.

To define how a Eclipse GlassFish web application handles response caching, you edit specific fields in the glassfish-web.xml file.

A servlet that uses caching is not portable.

For Javadoc tool pages relevant to caching servlet results, see the com.sun.appserv.web.cache package.

For information about JSP caching, see JSP Caching.

The following topics are addressed here:

Caching Features

The Eclipse GlassFish has the following web application response caching capabilities:

  • Caching is configurable based on the servlet name or the URI.

  • When caching is based on the URI, this includes user specified parameters in the query string. For example, a response from /garden/catalog?category=roses is different from a response from /garden/catalog?category=lilies. These responses are stored under different keys in the cache.

  • Cache size, entry timeout, and other caching behaviors are configurable.

  • Entry timeout is measured from the time an entry is created or refreshed. To override this timeout for an individual cache mapping, specify the cache-mapping subelement timeout.

  • To determine caching criteria programmatically, write a class that implements the com.sun.appserv.web.cache.CacheHelper interface. For example, if only a servlet knows when a back end data source was last modified, you can write a helper class to retrieve the last modified timestamp from the data source and decide whether to cache the response based on that timestamp.

  • To determine cache key generation programmatically, write a class that implements the com.sun.appserv.web.cache.CacheKeyGenerator interface. See The CacheKeyGenerator Interface.

  • All non-ASCII request parameter values specified in cache key elements must be URL encoded. The caching subsystem attempts to match the raw parameter values in the request query string.

  • Since newly updated classes impact what gets cached, the web container clears the cache during dynamic deployment or reloading of classes.

  • The following HttpServletRequest request attributes are exposed.

    • com.sun.appserv.web.cachedServletName, the cached servlet target

    • com.sun.appserv.web.cachedURLPattern, the URL pattern being cached

  • Results produced by resources that are the target of a RequestDispatcher.include() or RequestDispatcher.forward() call are cached if caching has been enabled for those resources. For details, see "cache-mapping" in Eclipse GlassFish Application Deployment Guide and "dispatcher" in Eclipse GlassFish Application Deployment Guide. These are elements in the glassfish-web.xml file.

Default Cache Configuration

If you enable caching but do not provide any special configuration for a servlet or JSP, the default cache configuration is as follows:

  • The default cache timeout is 30 seconds.

  • Only the HTTP GET method is eligible for caching.

  • HTTP requests with cookies or sessions automatically disable caching.

  • No special consideration is given to Pragma:, Cache-control:, or Vary: headers.

  • The default key consists of the Servlet Path (minus pathInfo and the query string).

  • A "least recently used" list is maintained to evict cache entries if the maximum cache size is exceeded.

  • Key generation concatenates the servlet path with key field values, if any are specified.

  • Results produced by resources that are the target of a RequestDispatcher.include() or RequestDispatcher.forward() call are never cached.

Caching Example

Here is an example cache element in the glassfish-web.xml file:

<cache max-capacity="8192" timeout="60">
<cache-helper name="myHelper" class-name="MyCacheHelper"/>
<cache-mapping>
    <servlet-name>myservlet</servlet-name>
    <timeout name="timefield">120</timeout>
    <http-method>GET</http-method>
    <http-method>POST</http-method>
</cache-mapping>
<cache-mapping>
    <url-pattern> /catalog/* </url-pattern>
    <!-- cache the best selling category; cache the responses to
       -- this resource only when the given parameters exist. Cache
       -- only when the catalog parameter has 'lilies' or 'roses'
       -- but no other catalog varieties:
      -- /orchard/catalog?best&category='lilies'
      -- /orchard/catalog?best&category='roses'
      -- but not the result of
       -- /orchard/catalog?best&category='wild'
    -->
    <constraint-field name='best' scope='request.parameter'/>
    <constraint-field name='category' scope='request.parameter'>
        <value> roses </value>
        <value> lilies </value>
    </constraint-field>
     <!-- Specify that a particular field is of given range but the
       -- field doesn't need to be present in all the requests -->
    <constraint-field name='SKUnum' scope='request.parameter'>
        <value match-expr='in-range'> 1000 - 2000 </value>
    </constraint-field>
    <!-- cache when the category matches with any value other than
       -- a specific value -->
    <constraint-field name="category" scope="request.parameter>
        <value match-expr="equals" cache-on-match-failure="true">
       bogus
        </value>
    </constraint-field>
</cache-mapping>
<cache-mapping>
    <servlet-name> InfoServlet </servlet-name>
    <cache-helper-ref>myHelper</cache-helper-ref>
</cache-mapping>
</cache>

For more information about the glassfish-web.xml caching settings, see "cache" in Eclipse GlassFish Application Deployment Guide.

The CacheKeyGenerator Interface

The built-in default CacheHelper implementation allows web applications to customize the key generation. An application component (in a servlet or JSP) can set up a custom CacheKeyGenerator implementation as an attribute in the ServletContext.

The name of the context attribute is configurable as the value of the cacheKeyGeneratorAttrName property in the default-helper element of the glassfish-web.xml deployment descriptor. For more information, see "default-helper" in Eclipse GlassFish Application Deployment Guide.

About the Servlet Engine

Servlets exist in and are managed by the servlet engine in the Eclipse GlassFish. The servlet engine is an internal object that handles all servlet meta functions. These functions include instantiation, initialization, destruction, access from other components, and configuration management.

The following topics are addressed here:

Instantiating and Removing Servlets

After the servlet engine instantiates the servlet, the servlet engine calls the servlet’s init method to perform any necessary initialization. You can override this method to perform an initialization function for the servlet’s life, such as initializing a counter.

When a servlet is removed from service, the servlet engine calls the destroy method in the servlet so that the servlet can perform any final tasks and deallocate resources. You can override this method to write log messages or clean up any lingering connections that won’t be caught in garbage collection.

Request Handling

When a request is made, the Eclipse GlassFish hands the incoming data to the servlet engine. The servlet engine processes the request’s input data, such as form data, cookies, session information, and URL name-value pairs, into an HttpServletRequest request object type.

The servlet engine also creates an HttpServletResponse response object type. The engine then passes both as parameters to the servlet’s service method.

In an HTTP servlet, the default service method routes requests to another method based on the HTTP transfer method: POST, GET, DELETE, HEAD, OPTIONS, PUT, or TRACE. For example, HTTP POST requests are sent to the doPost method, HTTP GET requests are sent to the doGet method, and so on. This enables the servlet to process request data differently, depending on which transfer method is used. Since the routing takes place in the service method, you generally do not override service in an HTTP servlet. Instead, override doGet, doPost, and so on, depending on the request type you expect.

To perform the tasks to answer a request, override the service method for generic servlets, and the doGet or doPost methods for HTTP servlets. Very often, this means accessing EJB components to perform business transactions, then collating the information in the request object or in a JDBC ResultSet object.

Using JavaServer Pages

The Eclipse GlassFish supports the following JSP features:

  • JavaServer Pages (JSP) Specification

  • Precompilation of JSP files, which is especially useful for production servers

  • JSP tag libraries and standard portable tags

For information about creating JSP files, see the JavaServer Pages web site at https://jakarta.ee/specifications/pages/.

This section describes how to use JavaServer Pages (JSP files) as page templates in a Eclipse GlassFish web application.

The following topics are addressed here:

JSP Tag Libraries and Standard Portable Tags

Eclipse GlassFish supports tag libraries and standard portable tags. For more information, see the JavaServer Pages Standard Tag Library (JSTL) page at https://jakarta.ee/specifications/tags/.

Web applications don’t need to bundle copies of the jsf-impl.jar or appserv-jstl.jar JSP tag libraries (in as-install/lib) to use JavaServer Faces technology or JSTL, respectively. These tag libraries are automatically available to all web applications.

However, the as-install/lib/jspcachtags.jar tag library for JSP caching is not automatically available to web applications. See JSP Caching, next.

JSP Caching

JSP caching lets you cache tag invocation results within the Java engine. Each can be cached using different cache criteria. For example, suppose you have invocations to view stock quotes, weather information, and so on. The stock quote result can be cached for 10 minutes, the weather report result for 30 minutes, and so on.

The following topics are addressed here:

For more information about response caching as it pertains to servlets, see Caching Servlet Results.

Enabling JSP Caching

To globally enable JSP caching, set the jspCachingEnabled property to true. The default is false. For example:

asadmin set server-config.web-container.property.jspCachingEnabled="true"

For more information about the asadmin set command, see the Eclipse GlassFish Reference Manual.

To enable JSP caching for a single web application, follow these steps:

  1. Extract the META-INF/jspcachtags.tld file from the as-install/modules/web-glue.jar file.

  2. Create a new JAR file (for example, jspcachtags.jar) containing just the META-INF/jspcachtags.tld file previously extracted.

  3. Bundle this new JAR file in the WEB-INF/lib directory of your web application.

Web applications that use JSP caching without bundling the tag library are not portable.

Refer to Eclipse GlassFish tags in JSP files as follows:

<%@ taglib prefix="prefix" uri="http://glassfish.org/taglibs/cache" %>

Subsequently, the cache tags are available as <`prefix:cache>` and <`prefix:flush>`. For example, if your prefix is mypfx, the cache tags are available as <mypfx:cache> and <mypfx:flush>.

Caching Scope

JSP caching is available in three different scopes: request, session, and application. The default is application. To use a cache in request scope, a web application must specify the com.sun.appserv.web.taglibs.cache.CacheRequestListener in its web.xml deployment descriptor, as follows:

<listener>
   <listener-class>
      com.sun.appserv.web.taglibs.cache.CacheRequestListener
   </listener-class>
</listener>

Likewise, for a web application to utilize a cache in session scope, it must specify the com.sun.appserv.web.taglibs.cache.CacheSessionListener in its web.xml deployment descriptor, as follows:

<listener>
   <listener-class>
      com.sun.appserv.web.taglibs.cache.CacheSessionListener
   </listener-class>
</listener>

To utilize a cache in application scope, a web application need not specify any listener. The com.sun.appserv.web.taglibs.cache.CacheContextListener is already specified in the jspcachtags.tld file.

The cache Tag

The cache tag caches the body between the beginning and ending tags according to the attributes specified. The first time the tag is encountered, the body content is executed and cached. Each subsequent time it is run, the cached content is checked to see if it needs to be refreshed and if so, it is executed again, and the cached data is refreshed. Otherwise, the cached data is served.

Attributes of cache

The following table describes attributes for the cache tag.

Table 7-1 The cache Attributes

Attribute Default Description

key

ServletPath`_`Suffix

(optional) The name used by the container to access the cached entry. The cache key is suffixed to the servlet path to generate a key to access the cached entry. If no key is specified, a number is generated according to the position of the tag in the page.

timeout

60s

(optional) The time in seconds after which the body of the tag is executed and the cache is refreshed. By default, this value is interpreted in seconds. To specify a different unit of time, add a suffix to the timeout value as follows: s for seconds, m for minutes, h for hours, d for days. For example, 2h specifies two hours.

nocache

false

(optional) If set to true, the body content is executed and served as if there were no cache tag. This offers a way to programmatically decide whether the cached response is sent or whether the body has to be executed, though the response is not cached.

refresh

false

(optional) If set to true, the body content is executed and the response is cached again. This lets you programmatically refresh the cache immediately regardless of the timeout setting.

scope

application

(optional) The scope of the cache. Can be request, session, or application. See Caching Scope.

Example of cache

The following example represents a cached JSP file:

<%@ taglib prefix="mypfx" uri="http://glassfish.org/taglibs/cache" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<mypfx:cache                 key="${sessionScope.loginId}"
            nocache="${param.nocache}"
            refresh="${param.refresh}"
            timeout="10m">
<c:choose>
    <c:when test="${param.page == 'frontPage'}">
        <%-- get headlines from database --%>
    </c:when>
    <c:otherwise>
        ...
    </c:otherwise>
</c:choose>
</mypfx:cache>
<mypfx:cache timeout="1h">
<h2> Local News </h2>
    <%-- get the headline news and cache them --%>
</mypfx:cache>
The flush Tag

Forces the cache to be flushed. If a key is specified, only the entry with that key is flushed. If no key is specified, the entire cache is flushed.

Attributes of flush

The following table describes attributes for the flush tag.

Table 7-2 The flush Attributes

Attribute Default Description

key

ServletPath`_`Suffix

(optional) The name used by the container to access the cached entry. The cache key is suffixed to the servlet path to generate a key to access the cached entry. If no key is specified, a number is generated according to the position of the tag in the page.

scope

application

(optional) The scope of the cache. Can be request, session, or application. See Caching Scope.

Examples of flush

To flush the entry with key="foobar":

<mypfx:flush key="foobar"/>

To flush the entire cache:

<c:if test="${empty sessionScope.clearCache}">
   <mypfx:flush />
</c:if>

Options for Compiling JSP Files

Eclipse GlassFish provides the following ways of compiling JSP source files into servlets:

Creating and Managing Sessions

This section describes how to create and manage HTTP sessions that allows users and transaction information to persist between interactions.

The following topics are addressed here:

Configuring Sessions

The following topics are addressed here:

HTTP Sessions, Cookies, and URL Rewriting

To configure whether and how HTTP sessions use cookies and URL rewriting, edit the session-properties and cookie-properties elements in the glassfish-web.xml file for an individual web application. For more about the properties you can configure, see "session-properties" in Eclipse GlassFish Application Deployment Guide and "cookie-properties" in Eclipse GlassFish Application Deployment Guide.

For information about configuring default session properties for the entire web container, see Using the default-web.xml File and the Eclipse GlassFish High Availability Administration Guide.

Coordinating Session Access

Make sure that multiple threads don’t simultaneously modify the same session object in conflicting ways. If the persistence type is replicated (see The replicated Persistence Type), the following message in the log file indicates that this might be happening:

Primary Key Constraint violation while saving session session_id

This is especially likely to occur in web applications that use HTML frames where multiple servlets are executing simultaneously on behalf of the same client. A good solution is to ensure that one of the servlets modifies the session and the others have read-only access.

Saving Sessions During Redeployment

Whenever a redeployment is done, the sessions at that transit time become invalid unless you use the --keepstate=true option of the asadmin redeploy command. For example:

asadmin redeploy --keepstate=true --name hello.war

For details, see the Eclipse GlassFish Reference Manual.

The default for --keepstate is false. This option is supported only on the default server instance, named server. It is not supported and ignored for any other target.

For web applications, this feature is applicable only if in the glassfish-web-app.xml file the persistence-type attribute of the session-manager element is file.

If any active web session fails to be preserved or restored, none of the sessions will be available when the redeployment is complete. However, the redeployment continues and a warning is logged.

The new class loader of the redeployed application is used to deserialize any sessions previously saved. The usual restrictions about serialization and deserialization apply. For example, any application-specific class referenced by a session attribute may evolve only in a backward-compatible fashion. For more information about class loaders, see Class Loaders.

Logging Session Attributes

You can write session attribute values to an access log. The access log format token %session.name% logs one of the following:

  • The value of the session attribute with the name name

  • NULL-SESSION-ATTRIBUTE-name if the named attribute does not exist in the session

  • NULL-SESSION if no session exists

For more information about access logging and format tokens, see online help for the Access Log tab of the HTTP Service page in the Administration Console.

Distributed Sessions and Persistence

A distributed HTTP session can run in multiple Eclipse GlassFish instances, provided the following criteria are met:

  • Each server instance has the same distributable web application deployed to it. The web-app element of the web.xml deployment descriptor file must have the distributable subelement specified.

  • The web application uses high-availability session persistence. If a non-distributable web application is configured to use high-availability session persistence, a warning is written to the server log, and the session persistence type reverts to memory. See The replicated Persistence Type.

  • All objects bound into a distributed session must be of the types listed in Table 7-3.

  • The web application must be deployed using the deploy or deploydir command with the --availabilityenabled option set to true. See the Eclipse GlassFish Reference Manual.

Contrary to the Servlet 5.0 specification, Eclipse GlassFish does not throw an IllegalArgumentException if an object type not supported for failover is bound into a distributed session.

Keep the distributed session size as small as possible. Session size has a direct impact on overall system throughput.

In the event of an instance or hardware failure, another server instance can take over a distributed session, with the following limitations:

  • If a distributable web application references a Jakarta EE component or resource, the reference might be lost. See Table 7-3 for a list of the types of references that HTTPSession failover supports.

  • References to open files or network connections are lost.

For information about how to work around these limitations, see the Eclipse GlassFish Deployment Planning Guide.

In the following table, No indicates that failover for the object type might not work in all cases and that no failover support is provided. However, failover might work in some cases for that object type. For example, failover might work because the class implementing that type is serializable.

For more information about the InitialContext, see Accessing the Naming Context. For more information about transaction recovery, see Using the Transaction Service. For more information about Administered Objects, see "Administering JMS Physical Destinations" in Eclipse GlassFish Administration Guide.

Table 7-3 Object Types Supported for Jakarta EE Web Application Session State Failover

Java Object Type Failover Support

Colocated or distributed stateless session, stateful session, or entity bean reference

Yes

JNDI context

Yes, InitialContext and java:comp/env

UserTransaction

Yes, but if the instance that fails is never restarted, any prepared global transactions are lost and might not be correctly rolled back or committed.

JDBC DataSource

No

Java Message Service (JMS) ConnectionFactory, Destination

No

Jakarta Mail Session

No

Connection Factory

No

Administered Object

No

Web service reference

No

Serializable Java types

Yes

Extended persistence context

No

Session Managers

A session manager automatically creates new session objects whenever a new session starts. In some circumstances, clients do not join the session, for example, if the session manager uses cookies and the client does not accept cookies.

Eclipse GlassFish offers these session management options, determined by the session-manager element’s persistence-type attribute in the glassfish-web.xml file:

If the session manager configuration contains an error, the error is written to the server log and the default (memory) configuration is used.

For more information, see "session-manager" in Eclipse GlassFish Application Deployment Guide.

The memory Persistence Type

This persistence type is not designed for a production environment that requires session persistence. It provides no session persistence. However, you can configure it so that the session state in memory is written to the file system prior to server shutdown.

To specify the memory persistence type for a specific web application, edit the glassfish-web.xml file as in the following example. The persistence-type attribute is optional, but must be set to memory if included. This overrides the web container availability settings for the web application.

<glassfish-web-app>
...

<session-config>
    <session-manager persistence-type="memory" />
        <manager-properties>
            <property name="sessionFilename" value="sessionstate" />
        </manager-properties>
    </session-manager>
    ...
</session-config>
...
</glassfish-web-app>

The only manager property that the memory persistence type supports is sessionFilename, which is listed under "manager-properties" in Eclipse GlassFish Application Deployment Guide. The sessionFilename property specifies the name of the file where sessions are serialized and persisted if the web application or the server is stopped. To disable this behavior, specify an empty string as the value of sessionFilename. The default value is an empty string.

For more information about the glassfish-web.xml file, see the Eclipse GlassFish Application Deployment Guide.

The file Persistence Type

This persistence type provides session persistence to the local file system, and allows a single server domain to recover the session state after a failure and restart. The session state is persisted in the background, and the rate at which this occurs is configurable. The store also provides passivation and activation of the session state to help control the amount of memory used. This option is not supported in a production environment. However, it is useful for a development system with a single server instance.

Make sure the delete option is set in the server.policy file, or expired file-based sessions might not be deleted properly. For more information about server.policy, see The server.policy File.

To specify the file persistence type for a specific web application, edit the glassfish-web.xml file as in the following example. Note that persistence-type must be set to file. This overrides the web container availability settings for the web application.

<glassfish-web-app>
...
<session-config>
    <session-manager persistence-type="file">
        <store-properties>
            <property name="directory" value="sessiondir" />
        </store-properties>
    </session-manager>
    ...
</session-config>
...
</glassfish-web-app>

The file persistence type supports all the manager properties listed under "manager-properties" in Eclipse GlassFish Application Deployment Guide except sessionFilename, and supports the directory store property listed under "store-properties" in Eclipse GlassFish Application Deployment Guide.

For more information about the glassfish-web.xml file, see the Eclipse GlassFish Application Deployment Guide.

The replicated Persistence Type

The replicated persistence type uses other servers in the cluster for session persistence. Clustered server instances replicate session state. Each backup instance stores the replicated data in memory. This allows sessions to be distributed. For details, see Distributed Sessions and Persistence. In addition, you can configure the frequency and scope of session persistence. The other servers are also used as the passivation and activation store. Use this option in a production environment that requires session persistence.

To use the replicated persistence type, you must enable availability. Select the Availability Service component under the relevant configuration in the Administration Console. Check the Availability Service box. To enable availability for the web container, select the Web Container Availability tab, then check the Availability Service box. All instances in an Eclipse GlassFish cluster should have the same availability settings to ensure consistent behavior. For details, see the Eclipse GlassFish High Availability Administration Guide.

To change settings such as persistence frequency and persistence scope for the entire web container, use the Persistence Frequency and Persistence Scope drop-down lists on the Web Container Availability tab in the Administration Console, or use the asadmin set command. For example:

asadmin set
server-config.availability-service.web-container-availability.persistence-frequency=time-based

For more information, see the description of the asadmin set command in the Eclipse GlassFish Reference Manual.

To specify the replicated persistence type for a specific web application, edit the glassfish-web.xml file as in the following example. Note that persistence-type must be set to replicated. This overrides the web container availability settings for the web application.

<glassfish-web-app>
...
<session-config>
    <session-manager persistence-type="replicated">
        <manager-properties>
            <property name="persistenceFrequency" value="web-method" />
        </manager-properties>
        <store-properties>
            <property name="persistenceScope" value="session" />
        </store-properties>
    </session-manager>
    ...
</session-config>
...
</glassfish-web-app>

The replicated persistence type supports all the manager properties listed under "manager-properties" in Eclipse GlassFish Application Deployment Guide except sessionFilename, and supports the persistenceScope store property listed under "store-properties" in Eclipse GlassFish Application Deployment Guide.

For more information about the glassfish-web.xml file, see the Eclipse GlassFish Application Deployment Guide.

To specify that web sessions for which high availability is enabled are first buffered and then replicated using a separate asynchronous thread, use the --asyncreplication=true option of the asadmin deploy command. For example:

asadmin deploy --availabilityenabled=true --asyncreplication=true --name hello.war

If --asyncreplication is set to true (the default), performance is improved but availability is reduced. If the instance where states are buffered but not yet replicated fails, the states are lost. If set to false, performance is reduced but availability is guaranteed. States are not buffered but immediately transmitted to other instances in the cluster.

Using Comet

This section explains the Comet programming technique and how to create and deploy a Comet-enabled application with the Eclipse GlassFish.

The following topics are addressed here:

Introduction to Comet

Comet is a programming technique that allows a web server to send updates to clients without requiring the clients to explicitly request them.

This kind of programming technique is called server push, which means that the server pushes data to the client. The opposite style is client pull, which means that the client must pull the data from the server, usually through a user-initiated event, such as a button click.

Web applications that use the Comet technique can deliver updates to clients in a more timely manner than those that use the client-pull style while avoiding the latency that results from clients frequently polling the server.

One of the many use cases for Comet is a chat room application. When the server receives a message from one of the chat clients, it needs to send the message to the other clients without requiring them to ask for it. With Comet, the server can deliver messages to the clients as they are posted rather than expecting the clients to poll the server for new messages.

To accomplish this scenario, a Comet application establishes a long-lived HTTP connection. This connection is suspended on the server side, waiting for an event to happen before resuming. This kind of connection remains open, allowing an application that uses the Comet technique to send updates to clients when they are available rather than expecting clients to reopen the connection to poll the server for updates.

The Grizzly Implementation of Comet

A limitation of the Comet technique is that you must use it with a web server that supports non-blocking connections to avoid poor performance. Non-blocking connections are those that do not need to allocate one thread for each request. If the web server were to use blocking connections then it might end up holding many thousands of threads, thereby hindering its scalability.

The Eclipse GlassFish includes the Grizzly HTTP Engine, which enables asynchronous request processing (ARP) by avoiding blocking connections. Grizzly’s ARP implementation accomplishes this by using the Java NIO API.

With Java NIO, Grizzly enables greater performance and scalability by avoiding the limitations experienced by traditional web servers that must run a thread for each request. Instead, Grizzly’s ARP mechanism makes efficient use of a thread pool system and also keeps the state of requests so that it can keep requests alive without holding a single thread for each of them.

Grizzly supports two different implementations of Comet:

  • Grizzly Comet — Based on ARP, this includes a set of APIs that you use from a web component to enable Comet functionality in your web application. Grizzly Comet is specific to the Eclipse GlassFish.

  • Bayeux Protocol — Often referred to as Cometd, it consists of the JSON-based Bayeux message protocol, a set of Dojo or Ajax libraries, and an event handler. The Bayeux protocol uses a publish/subscribe model for server/client communication. The Bayeux protocol is portable, but it is container dependent if you want to invoke it from an Enterprise Java Beans (EJB ) component. The Grizzly implementation of Cometd consists of a servlet that you reference from your web application.

Client Technologies to Use With Comet

In addition to creating a web component that uses the Comet APIs, you need to enable your client to accept asynchronous updates from the web component. To accomplish this, you can use JavaScript, IFrames, or a framework, such as Dojo (http://dojotoolkit.org).

An IFrame is an HTML element that allows you to include other content in an HTML page. As a result, the client can embed updated content in the IFrame without having to reload the page.

The example in this tutorial employs a combination of JavaScript and IFrames to allow the client to accept asynchronous updates. A servlet included in the example writes out JavaScript code to one of the IFrames. The JavaScript code contains the updated content and invokes a function in the page that updates the appropriate elements in the page with the new content.

The next section explains the two kinds of connections that you can make to the server. While you can use any of the client technologies listed in this section with either kind of connection, it is more difficult to use JavaScript with an HTTP-streaming connection.

Types of Comet Connections

When working with Comet, as implemented in Grizzly, you have two different ways to handle client connections to the server:

  • HTTP Streaming

  • Long Polling

HTTP Streaming

The HTTP Streaming technique keeps a connection open indefinitely. It never closes, even after the server pushes data to the client.

In the case of HTTP streaming, the application sends a single request and receives responses as they come, reusing the same connection forever. This technique significantly reduces the network latency because the client and the server don’t need to open and close the connection.

The basic life cycle of an application using HTTP-streaming is:

request > suspend > data available > write response > data available > write response

The client makes an initial request and then suspends the request, meaning that it waits for a response. Whenever data is available, the server writes it to the response.

Long Polling

The long-polling technique is a combination of server-push and client-pull because the client needs to resume the connection after a certain amount of time or after the server pushes an update to the client.

The basic life cycle of an application using long-polling is:

request > suspend > data available > write response > resume

The client makes an initial request and then suspends the request. When an update is available, the server writes it to the response. The connection closes, and the client optionally resumes the connection.

How to Choose the Type of Connection

If you anticipate that your web application will need to send frequent updates to the client, you should use the HTTP-streaming connection so that the client does not have to frequently reestablish a connection. If you anticipate less frequent updates, you should use the long-polling connection so that the web server does not need to keep a connection open when no updates are occurring. One caveat to using the HTTP-streaming connection is that if you are streaming through a proxy, the proxy can buffer the response from the server. So, be sure to test your application if you plan to use HTTP-streaming behind a proxy.

Grizzly Comet

For details on using Grizzly Comet including a sample application, refer to the Grizzly Comet documentation.

Grizzly’s support for Comet includes a small set of APIs that make it easy to add Comet functionality to your web applications. The Grizzly Comet APIs that developers use most often are the following:

  • CometContext: A Comet context, which is a shareable space to which applications subscribe to receive updates.

  • CometEngine: The entry point to any component using Comet. Components can be servlets, JavaServer Pages ( JSP), JavaServer Faces components, or pure Java classes.

  • CometEvent: Contains the state of the CometContext object

  • CometHandler: The interface an application implements to be part of one or more Comet contexts.

The way a developer would use this API in a web component is to perform the following tasks:

  1. Register the context path of the application with the CometContext object:

    CometEngine cometEngine = CometEngine.getEngine();
CometContext cometContext = cometEngine.register(contextPath)

  2. Register the CometHandler implementation with the CometContext object:

    cometContext.addCometHandler(handler)

  3. Notify one or more CometHandler implementations when an event happens:

    cometContext.notify((Object)(handler))

Bayeux Protocol

The Bayeux protocol, often referred to as Cometd, greatly simplifies the use of Comet. No server-side coding is needed for servers such as Eclipse GlassFish that support the Bayeux protocol. Just enable Comet and the Bayeux protocol, then write and deploy the client.

The following topics are addressed here:

Enabling Comet

Before running a Comet-enabled application, you need to enable Comet in the HTTP listener for your application by setting a special attribute in the associated protocol configuration. The following example shows the asadmin set command that adds this attribute:

asadmin set server-config.network-config.protocols.protocol.http-1.http.comet-support-enabled="true"

Substitute the name of the protocol for http-1.

To Configure the web.xml File

To enable the Bayeux protocol on the Eclipse GlassFish, you must reference the CometdServlet in your web application’s web.xml file. In addition, if your web application includes a servlet, set the load-on-startup value for your servlet to 0 (zero) so that it will not load until the client makes a request to it.

  1. Open the web.xml file for your web application in a text editor.

  2. Add the following XML code to the web.xml file:

    <servlet>
   <servlet-name>Grizzly Cometd Servlet</servlet-name>
   <servlet-class>
      com.sun.grizzly.cometd.servlet.CometdServlet
   </servlet-class>
   <init-param>
      <description>
         expirationDelay is the long delay before a request is
         resumed. -1 means never.
      </description>
      <param-name>expirationDelay</param-name>
      <param-value>-1</param-value>
   </init-param>
   <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
   <servlet-name>Grizzly Cometd Servlet</servlet-name>
   <url-pattern>/cometd/*</url-pattern>
</servlet-mapping>

    Note that the load-on-startup value for the CometdServlet is 1.

  3. If your web application includes a servlet, set the load-on-startup value to 0 for your servlet (not the CometdServlet) as follows:

    <servlet>
   ...
   <load-on-startup>0</load-on-startup>
</servlet>

  4. Save the web.xml file.

To Write, Deploy, and Run the Client

  1. Add script tags to the HTML page. For example:

    <script type="text/javascript" src="chat.js"></script>

  2. In the script, call the needed libraries. For example:

    dojo.require("dojo.io.cometd");

  3. In the script, use publish and subscribe methods to send and receive messages. For example:

    cometd.subscribe("/chat/demo", false, room, "_chat");
cometd.publish("/chat/demo", { user: room._username, chat: text});

  4. Deploy the web application as you would any other web application. For example:

    asadmin deploy cometd-example.war

  5. Run the application as you would any other web application.

    The context root for the example chat application is /cometd and the HTML page is index.html. So the URL might look like this:

    http://localhost:8080/cometd/index.html

See Also

For more information about deployment in the Eclipse GlassFish, see the Eclipse GlassFish Application Deployment Guide.

For more information about the Bayeux protocol, see Bayeux Protocol (https://docs.cometd.org/current/reference/#_bayeux).

For more information about the Dojo toolkit, see http://dojotoolkit.org/.

Advanced Web Application Features

The following topics are addressed here:

Internationalization Issues

The following topics are addressed here:

The Server’s Default Locale

To set the default locale of the entire Eclipse GlassFish, which determines the locale of the Administration Console, the logs, and so on, use the Administration Console. Select the domain component. Then type a value in the Locale field. For details, click the Help button in the Administration Console.

Servlet Character Encoding

This section explains how the Eclipse GlassFish determines the character encoding for the servlet request and the servlet response. For encodings you can use, see http://docs.oracle.com/javase/8/docs/technotes/guides/intl/encoding.doc.html.

Servlet Request

When processing a servlet request, the server uses the following order of precedence, first to last, to determine the request character encoding:

  • The getCharacterEncoding method

  • A hidden field in the form, specified by the form-hint-field attribute of the parameter-encoding element in the glassfish-web.xml file

  • The default-charset attribute of the parameter-encoding element in the glassfish-web.xml file

  • The default, which is ISO-8859-1

For details about the parameter-encoding element, see "parameter-encoding" in Eclipse GlassFish Application Deployment Guide.

Servlet Response

When processing a servlet response, the server uses the following order of precedence, first to last, to determine the response character encoding:

  • The setCharacterEncoding or setContentType method

  • The setLocale method

  • The default, which is ISO-8859-1

Virtual Server Properties

You can set virtual server properties in the following ways:

  • You can define virtual server properties using the asadmin create-virtual-server command. For example:

    asadmin create-virtual-server --hosts localhost --property authRealm=ldap MyVS

    For details and a complete list of virtual server properties, see create-virtual-server(1).

  • You can define virtual server properties using the asadmin set command. For example:

    asadmin set server-config.http-service.virtual-server.MyVS.property.authRealm="ldap"

    For details, see set(1).

  • You can define virtual server properties using the Administration Console. Select the HTTP Service component under the relevant configuration, select Virtual Servers, and select the desired virtual server. Select Add Property, enter the property name and value, check the enable box, and select Save. For details and a complete list of virtual server properties, click the Help button in the Administration Console.

Some virtual server properties can be set for a specific web application. For details, see "glassfish-web-app" in Eclipse GlassFish Application Deployment Guide.

Class Loader Delegation

The Servlet specification recommends that a web application class loader look in the local class loader before delegating to its parent. To make the web application class loader follow the delegation model in the Servlet specification, set delegate="false" in the class-loader element of the glassfish-web.xml file. It’s safe to do this only for a web module that does not interact with any other modules.

The default value is delegate="true", which causes the web application class loader to delegate in the same manner as the other class loaders. Use delegate="true" for a web application that accesses EJB components or that acts as a web service client or endpoint. For details about glassfish-web.xml, see the Eclipse GlassFish Application Deployment Guide.

For a number of packages, including java. and javax., symbol resolution is always delegated to the parent class loader regardless of the delegate setting. This prevents applications from overriding core Java runtime classes or changing the API versions of specifications that are part of the Jakarta EE platform.

For general information about class loaders, see Class Loaders.

Using the default-web.xml File

You can use the default-web.xml file to define features such as filters and security constraints that apply to all web applications.

For example, directory listings are disabled by default for added security. To enable directory listings, in your domain’s default-web.xml file, search for the definition of the servlet whose servlet-name is equal to default, and set the value of the init-param named listings to true. Then redeploy your web application if it has already been deployed, or restart the server.

<init-param>
   <param-name>listings</param-name>
   <param-value>true</param-value>
</init-param>

If listings is set to true, you can also determine how directory listings are sorted. Set the value of the init-param named sortedBy to NAME, SIZE, or LAST_MODIFIED. Then redeploy your web application if it has already been deployed, or restart the server.

<init-param>
   <param-name>sortedBy</param-name>
   <param-value>LAST_MODIFIED</param-value>
</init-param>

The mime-mapping elements in default-web.xml are global and inherited by all web applications. You can override these mappings or define your own using mime-mapping elements in your web application’s web.xml file. For more information about mime-mapping elements, see the Servlet specification.

You can use the Administration Console to edit the default-web.xml file. For details, click the Help button in the Administration Console. As an alternative, you can edit the file directly using the following steps.

To Use the default-web.xml File

  1. Place the JAR file for the filter, security constraint, or other feature in the domain-dir/lib directory.

  2. Edit the domain-dir/config/default-web.xml file to refer to the JAR file.

  3. Restart the server.

Configuring Logging and Monitoring in the Web Container

For information about configuring logging and monitoring in the web container using the Administration Console, click the Help button in the Administration Console. Select Logger Settings under the relevant configuration, or select the Stand-Alone Instances component, select the instance from the table, and select the Monitor tab.

Configuring Idempotent URL Requests

An idempotent request is one that does not cause any change or inconsistency in an application when retried. To enhance the availability of your applications deployed on an Eclipse GlassFish cluster, configure the load balancer to retry failed idempotent HTTP requests on all the Eclipse GlassFish instances in a cluster. This option can be used for read-only requests, for example, to retry a search request.

The following topics are addressed here:

Specifying an Idempotent URL

To configure idempotent URL response, specify the URLs that can be safely retried in idempotent-url-pattern elements in the glassfish-web.xml file. For example:

<idempotent-url-pattern url-pattern="sun_java/*" no-of-retries="10"/>

For details, see "idempotent-url-pattern" in Eclipse GlassFish Application Deployment Guide.

If none of the server instances can successfully serve the request, an error page is returned.

Characteristics of an Idempotent URL

Since all requests for a given session are sent to the same application server instance, and if that Eclipse GlassFish instance is unreachable, the load balancer returns an error message. Normally, the request is not retried on another Eclipse GlassFish instance. However, if the URL pattern matches that specified in the glassfish-web.xml file, the request is implicitly retried on another Eclipse GlassFish instance in the cluster.

In HTTP, some methods (such as GET) are idempotent, while other methods (such as POST) are not. In effect, retrying an idempotent URL should not cause values to change on the server or in the database. The only difference should be a change in the response received by the user.

Examples of idempotent requests include search engine queries and database queries. The underlying principle is that the retry does not cause an update or modification of data.

A search engine, for example, sends HTTP requests with the same URL pattern to the load balancer. Specifying the URL pattern of the search request to the load balancer ensures that HTTP requests with the specified URL pattern are implicitly retried on another Eclipse GlassFish instance.

For example, if the request URL sent to the Eclipse GlassFish is of the type /search/something.html, then the URL pattern can be specified as /search/*.

Examples of non-idempotent requests include banking transactions and online shopping. If you retry such requests, money might be transferred twice from your account.

Header Management

In all Editions of the Eclipse GlassFish, the Enumeration from request.getHeaders() contains multiple elements (one element per request header) instead of a single, aggregated value.

The header names used in HttpServletResponse.addXXXHeader() and HttpServletResponse.setXXXHeader() are returned as they were created.

Configuring Valves and Catalina Listeners

You can configure custom valves and Catalina listeners for web modules or virtual servers by defining properties. A valve class must implement the org.apache.catalina.Valve interface from Tomcat or previous Eclipse GlassFish releases, or the org.glassfish.web.valve.GlassFishValve interface from the current Eclipse GlassFish release. A listener class for a virtual server must implement the org.apache.catalina.ContainerListener or org.apache.catalina.LifecycleListener interface. A listener class for a web module must implement the org.apache.catalina.ContainerListener , org.apache.catalina.LifecycleListener, or org.apache.catalina.InstanceListener interface.

In the glassfish-web.xml file, valve and listener properties for a web module look like this:

<glassfish-web-app ...>
   ...
   <property name="valve_1" value="org.glassfish.extension.Valve"/>
   <property name="listener_1" value="org.glassfish.extension.MyLifecycleListener"/>
</glassfish-web-app>

You can define these same properties for a virtual server. For more information, see Virtual Server Properties.

Alternate Document Roots

An alternate document root (docroot) allows a web application to serve requests for certain resources from outside its own docroot, based on whether those requests match one (or more) of the URI patterns of the web application’s alternate docroots.

To specify an alternate docroot for a web application or a virtual server, use the alternatedocroot_n property, where n is a positive integer that allows specification of more than one. This property can be a subelement of a glassfish-web-app element in the glassfish-web.xml file or a virtual server property. For more information about these elements, see "glassfish-web-app" in Eclipse GlassFish Application Deployment Guide.

A virtual server’s alternate docroots are considered only if a request does not map to any of the web modules deployed on that virtual server. A web module’s alternate docroots are considered only once a request has been mapped to that web module.

If a request matches an alternate docroot’s URI pattern, it is mapped to the alternate docroot by appending the request URI (minus the web application’s context root) to the alternate docroot’s physical location (directory). If a request matches multiple URI patterns, the alternate docroot is determined according to the following precedence order:

  • Exact match

  • Longest path match

  • Extension match

For example, the following properties specify three glassfish-web.xml docroots. The URI pattern of the first alternate docroot uses an exact match, whereas the URI patterns of the second and third alternate docroots use extension and longest path prefix matches, respectively.

<property name="alternatedocroot_1" value="from=/my.jpg dir=/srv/images/jpg"/>
<property name="alternatedocroot_2" value="from=*.jpg dir=/srv/images/jpg"/>
<property name="alternatedocroot_3" value="from=/jpg/* dir=/src/images"/>

The value of each alternate docroot has two components: The first component, from, specifies the alternate docroot’s URI pattern, and the second component, dir, specifies the alternate docroot’s physical location (directory).

Suppose the above examples belong to a web application deployed at http://company22.com/myapp. The first alternate docroot maps any requests with this URL:

http://company22.com/myapp/my.jpg

To this resource:

/svr/images/jpg/my.jpg

The second alternate docroot maps any requests with a *.jpg suffix, such as:

http://company22.com/myapp/*.jpg

To this physical location:

/svr/images/jpg

The third alternate docroot maps any requests whose URI starts with /myapp/jpg/, such as:

http://company22.com/myapp/jpg/*

To the same directory as the second alternate docroot.

For example, the second alternate docroot maps this request:

http://company22.com/myapp/abc/def/my.jpg

To:

/srv/images/jpg/abc/def/my.jpg

The third alternate docroot maps:

http://company22.com/myapp/jpg/abc/resource

To:

/srv/images/jpg/abc/resource

If a request does not match any of the target web application’s alternate docroots, or if the target web application does not specify any alternate docroots, the request is served from the web application’s standard docroot, as usual.

Using a context.xml File

You can define a context.xml file for all web applications, for web applications assigned to a specific virtual server, or for a specific web application.

To define a global context.xml file, place the file in the domain-dir/config directory and name it context.xml.

Use the contextXmlDefault property to specify the name and the location, relative to domain-dir, of the context.xml file for a specific virtual server. Specify this property in one of the following ways:

  • In the Administration Console, open the HTTP Service component under the relevant configuration. Open the Virtual Servers component and scroll down to the bottom of the page. Enter contextXmlDefault as the property name and the path and file name relative to domain-dir as the property value.

  • Use the asadmin create-virtual-server command. For example:

    asadmin create-virtual-server --property contextXmlDefault=config/vs1ctx.xml vs1

  • Use the asadmin set command for an existing virtual server. For example:

    asadmin set server-config.http-service.virtual-server.vs1.property.contextXmlDefault=config/myctx.xml

To define a context.xml file for a specific web application, place the file in the META-INF directory and name it context.xml.

For more information about virtual server properties, see Virtual Server Properties. For more information about the context.xml file, see The Context Container (http://tomcat.apache.org/tomcat-5.5-doc/config/context.html). Context parameters, environment entries, and resource definitions in context.xml are supported in the Eclipse GlassFish.

Enabling WebDav

To enable WebDav in the Eclipse GlassFish, you edit the web.xml and glassfish-web.xml files as follows.

First, enable the WebDav servlet in your web.xml file:

<servlet>
   <servlet-name>webdav</servlet-name>
   <servlet-class>org.apache.catalina.servlets.WebdavServlet</servlet-class>
   <init-param>
      <param-name>debug</param-name>
      <param-value>0</param-value>
   </init-param>
   <init-param>
      <param-name>listings</param-name>
      <param-value>true</param-value>
   </init-param>
   <init-param>
      <param-name>readonly</param-name>
      <param-value>false</param-value>
   </init-param>
</servlet>

Then define the servlet mapping associated with your WebDav servlet in your web.xml file:

<servlet-mapping>
   <servlet-name>webdav</servlet-name>
   <url-pattern>/webdav/*</url-pattern>
</servlet-mapping>

To protect the WebDav servlet so other users can’t modify it, add a security constraint in your web.xml file:

<security-constraint>
   <web-resource-collection>
      <web-resource-name>Login Resources</web-resource-name>
      <url-pattern>/webdav/*</url-pattern>
   </web-resource-collection>
   <auth-constraint>
      <role-name>Admin</role-name>
   </auth-constraint>
   <user-data-constraint>
      <transport-guarantee>NONE</transport-guarantee>
   </user-data-constraint>
   <login-config>
      <auth-method>BASIC</auth-method>
      <realm-name>default</realm-name>
   </login-config>
   <security-role>
      <role-name>Admin</role-name>
   </security-role>
</security-constraint>

Then define a security role mapping in your glassfish-web.xml file:

<security-role-mapping>
   <role-name>Admin</role-name>
   <group-name>Admin</group-name>
</security-role-mapping>

If you are using the file realm, create a user and password. For example:

asadmin create-file-user --groups Admin --authrealmname default admin

Enable the security manager as described in Enabling and Disabling the Security Manager.

You can now use any WebDav client by connecting to the WebDav servlet URL, which has this format:

http://host:port/context-root/webdav/file

For example:

http://localhost:80/glassfish-webdav/webdav/index.html

You can add the WebDav servlet to your default-web.xml file to enable it for all applications, but you can’t set up a security role mapping to protect it.

Using SSI

To enable SSI (server-side includes) processing for a specific web module, add the SSIServlet to your web.xml file as follows:

<web-app>
   <servlet>
      <servlet-name>ssi</servlet-name>
      <servlet-class>org.apache.catalina.ssi.SSIServlet</servlet-class>
   </servlet>
   ...
   <servlet-mapping>
      <servlet-name>ssi</servlet-name>
      <url-pattern>*.shtml</url-pattern>
   </servlet-mapping>
   ...
   <mime-mapping>
      <extension>shtml</extension>
      <mime-type>text/html</mime-type>
   </mime-mapping>
</web-app>

To enable SSI processing for all web modules, un-comment the corresponding sections in the default-web.xml file.

If the mime-mapping is not specified in web.xml, Eclipse GlassFish attempts to determine the MIME type from default-web.xml or the operating system default.

You can configure the following init-param values for the SSIServlet.

Table 7-4 SSIServlet init-param Values

init-param Type Default Description

buffered

boolean

false

Specifies whether the output should be buffered.

debug

int

0 (for no debugging)

Specifies the debugging level.

expires

Long

Expires header in HTTP response not set

Specifies the expiration time in seconds.

inputEncoding

String

operating system encoding

Specifies encoding for the SSI input if there is no URL content encoding specified.

isVirtualWebappRelative

boolean

false (relative to the given SSI file)

Specifies whether the virtual path of the #include directive is relative to the content-root.

outputEncoding

String

UTF-8

Specifies encoding for the SSI output.

For more information about SSI, see http://httpd.apache.org/docs/2.2/mod/mod_include.html.

Using CGI

To enable CGI (common gateway interface) processing for a specific web module, add the CGIServlet to your web.xml file as follows:

<web-app>
   <servlet>
      <servlet-name>cgi</servlet-name>
      <servlet-class>org.apache.catalina.servlets.CGIServlet</servlet-class>
   </servlet>
   ...
   <servlet-mapping>
      <servlet-name>cgi</servlet-name>
      <url-pattern>/cgi-bin/*</url-pattern>
   </servlet-mapping>
</web-app>

To enable CGI processing for all web modules, un-comment the corresponding sections in the default-web.xml file.

Package the CGI program under the cgiPathPrefix. The default cgiPathPrefix is WEB-INF/cgi. For security, it is highly recommended that the contents and binaries of CGI programs be prohibited from direct viewing or download. For information about hiding directory listings, see Using the default-web.xml File.

Invoke the CGI program using a URL of the following format:

http://host:8080/context-root/cgi-bin/cgi-name

For example:

http://localhost:8080/mycontext/cgi-bin/hello

You can configure the following init-param values for the CGIServlet.

Table 7-5 CGIServlet init-param Values

init-param Type Default Description

cgiPathPrefix

String

WEB-INF/cgi

Specifies the subdirectory containing the CGI programs.

debug

int

0 (for no debugging)

Specifies the debugging level.

executable

String

perl

Specifies the executable for running the CGI script.

parameterEncoding

String

System.getProperty`("file.encoding",` "UTF-8")

Specifies the parameter’s encoding.

passShellEnvironment

boolean

false

Specifies whether to pass shell environment properties to the CGI program.

To work with a native executable, do the following:

  1. Set the value of the init-param named executable to an empty String in the web.xml file.

  2. Make sure the executable has its executable bits set correctly.

  3. Use directory deployment to deploy the web module. Do not deploy it as a WAR file, because the executable bit information is lost during the process of jar and unjar. For more information about directory deployment, see the Eclipse GlassFish Application Deployment Guide.