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TABLE OF CONTENT

1 Foreword *

2 Architecture and principles *

3 ICP messages *
  3.1 Standard *
  3.2 Messages *
      3.2.1 ICP_OP_INI *
      3.2.2 ICP_OP_ARCHIVE_STATUS *
      3.2.3 ICP_OP_ARCHIVE_UPDATE *
      3.2.4 ICP_OP_STAT_QUERY *
      3.2.5 ICP_OP_STAT_STATUS *
      3.2.6 ICP_OP_STAT _UPDATE *
      3.2.7 ICP_OP_LOG *
      3.2.8 ICP_OP_FIN *

  3.3 Protocol *
    3.3.1 Poll mechanism *
    3.3.2 Periodic refresh
*

4 Parameters *
  4.1 cachePath *
  4.2 toTrace *
  4.3 toStat *
  4.4 ID *
  4.5 logfile *
  4.6 remoteLocations *
  4.7 expiration *
  4.8 contextPath *
  4.9 useBundleSpace *
  4.10 Diskless *
  4.11 Multicast *
  4.12 MulticastGroup *
  4.13 MulticastPort *
  4.14 RemAddrs *
  4.15 RemPorts *
  4.16 allPermissionPolicy *
  4.17 defaultPolicy *
  4.18 keystore *
  4.19 keystorePassword *
  4.20 CAURL *
  4.21 CRLURL *
  4.22 CALDAPuser *
  4.23 CALDAPpasswd *
  4.24 CRLLDAPuser *
  4.25 CRLLDAPpasswd *
  4.26 CRLperiod *

5 Statistics and troubleshooting *

6 Notes on implementation *
  6.1 Dynamic update *
    6.1.1 Definition section *
    6.1.2 Loaded/defined section
*
  6.2 Resource handling *

7 Special cases *
  7.1 RequestDispatcher *
  7.2 Use of SSL *
  7.3 Load test *
  7.4 Functional tests *
    7.4.1 Update *
    7.4.2 Security *
    7.4.3 Misc
*

8 Limitations *

9 Differences between Application Server, JES 2 and diskless versions *

10 Miscellaneous *
  10.1 License *
  10.2 Deliveries *

TABLE OF FIGURES

Figure 1: Diskless architecture *

Figure 2: Statistics using ServletStat *

Figure 3: log using ServletLog *

Figure 4: Selection of the client on DisklessLog *

Figure 5: Diskless client log display with DisklessLog *

Figure 6: ServletUpdate definition *

Figure 7: ServletUpdate list *


Diskless embedded server version


  1. Foreword

    This document describes the diskless version of JSPservletPkg.

    JSPservletPkg is a complete implementation for servlets and JSP handling from a remote repository and with dynamic update.

    The diskless version is based on the embedded version and like embedded version has been tested so far only with Java Embedded Server 2 (JES 2) from Sun.

    The document doesnít refer to the Embedded version.

  2. Architecture and principles

    Diskless version can be configured either as a diskless client that can ROMed and doesnít need access to a local drive or either as a diskless server that is:

    1. A full embedded server able to host archives
    2. A server able to store configurations, logs and statistics for any number of diskless clients

    diskless servers managing persistent data and diskless clients, all of them hosting Web archive

    Figure 1: Diskless architecture

    Pagebox instances remain independent:

    • Each Diskless server maintains its local data (archive list, log and statistic files).
    • It also maintains data on behalf of diskless clients.
    • Diskless data are replicated. If on a given subnet (in case of multicast), there are 20 diskless clients and 2 diskless servers, each diskless server will maintain the data of the 20 clients

    Client data size is small but possibly logs. As diskless clients also send log messages on the wire, it has a consequence. Whereas intensive logging has a negligible impact for Application Server and Embedded server version it should be avoided as much as possible on diskless clients.

    Diskless clients and server communicate using new ICP messages, so in UDP either in unicast or multicast.

    The protocol is designed for fault tolerance.

  3. ICP messages

    1. Standard

      Diskless version uses ICP messages as defined in RFC 2186 and RFC 2187.

      They have a header described by the following C structure:

      struct _icp_common_t {
      	unsigned char opcode;	/* opcode */
      	unsigned char version;	/* version number */
      	unsigned short length;	/* total length (bytes) */
      	u_num32 reqnum;		/* req number (req'd for UDP) */
      	u_num32 flags;
      	u_num32 pad;
      	u_num32 shostid;	/* sender host id */
      	/* diskless extension */
      	u_num64 lastModified;	/* timestamp */
      	char[] ID;		/* issuer unique identifier
      				*  variable length delimited by a 0 and followed by the payload */
      };

      The opcode describes the message. Diskless version uses opcodes undefined in the standard.
      It doesnít use flags and pad fields and sets the version to two.

    2. Messages

      1. ICP_OP_INI

        Opcode: 5.

        PageBox initialization message issued by diskless client.

        Payload: none.

        Purpose: Query for archive names.

      2. ICP_OP_ARCHIVE_STATUS

        Opcode: 6.

        PageBox response returned by diskless server when it receives an ICP_OP_INI.

        Payload: serialized properties whose keys are archive names and values are download locations.

        Purpose: Provide the list of archives to manage to the diskless clients.

      3. ICP_OP_ARCHIVE_UPDATE

        Opcode: 13.

        PageBox archive update message sent by diskless client.

        Payload: serialized properties whose keys are archive names and values are download locations.

        Purpose: notify diskless servers updated list of archives managed by the client.

        This message is sent periodically (every SCANPERIOD = 1 minute in the current version) to address cases where a diskless server is not up when the diskless client adds, delete or change an archive.

      4. ICP_OP_STAT_QUERY

        Opcode: 7.

        Query for statistics issued by diskless client.

        Payload: none. The ID is made of the unique identifier of the client followed by slash ("/") and by the archive name.

        The initialization protocol is:

        Client  Server
        ICP_OP_INI==> 
         <==ICP_OP_ARCHIVE_STATUS
        For each archive managed by the client
        ICP_OP_STAT_QUERY
        ==> 
         <==ICP_OP_STAT_STATUS

      5. ICP_OP_STAT_STATUS

        Opcode: 12.

        PageBox response returned by diskless server when it receives an ICP_OP_STAT_QUERY.

        Payload: serialized properties whose keys are servlet names and values are invocation numbers.

        Purpose: Provide current statistics to the client before first invocation by browser users.

      6. ICP_OP_STAT _UPDATE

        Opcode: 14.

        PageBox statistics update message sent by diskless client.

        Payload: serialized properties whose keys are servlet names and values are invocation numbers.

        Purpose: Save statistics on server side.

        This message is sent periodically (every SCANPERIOD = 1 minute in the current version).

      7. ICP_OP_LOG

        Opcode: 8.

        PageBox log message sent by diskless client.

        Payload: message sent by diskless client.

        Purpose: Update log on server side.

      8. ICP_OP_FIN

        Opcode: 9.

        Message issued by diskless client to notify diskless servers of its termination.

        Payload: none.

        When a diskless server receives ICP_OP_FIN, it closes the relevant log file (identified by the ID carried in ICP_OP_FIN.

    3. Protocol

      The protocol is designed for fault tolerance. The unavailability of a server at a given time doesnít compromise the operations of a set of diskless servers and clients.

      1. Poll mechanism

        At initialization, a diskless client sends an ICP_OP_INI message to all servers.

        All up servers answer and the client selects the ICP_OP_ARCHIVE_STATUS answer whose lastModified field is the most recent to get the most up to date archive list. If a server was not up when the client updated lastly its archive definition, its response is not used.

        The same mechanism is used for statistics (messages ICP_OP_STAT_QUERY and ICP_OP_STAT_STATUS).

      2. Periodic refresh

        Suppose the administrator adds an archive to the archive list of a diskless client.

        Then the client sends an ICP_OP_ARCHIVE_UPDATE message. Server A is up and records the update. Then it is stopped. A server B is started.

        Now the administrator changes the location of an archive of a diskless client.

        The client sends an ICP_OP_ARCHIVE_UPDATE. Server B records that update.

        Now neither server A nor server B has an information that describes correctly the state of the client.

        To address this issue, update messages are send periodically even if no update occurs in a given session in order to refresh servers with a longer inactivity. It has also an important consequence. One can add a diskless server dynamically. One minute later, it will be up to date.

  4. Parameters

    This version is designed to be deployed in JES2 bundles. So its archive must have a Manifest like this:

    Bundle-Name: JSPservlet
    Bundle-Description: JSPservlet
    Bundle-Version: 1.0.1
    Bundle-DocURL: http://java.sun.com/products/embeddedserver
    Bundle-ContactAddress: alexis.grandemange@pagebox.net
    Bundle-Activator: JSPservletPkg.JSPhandler
    Import-Package: org.osgi.service.http,
      javax.servlet; specification-version=2.1.1,
      javax.servlet.http; specification-version=2.1.1,
      com.sun.jes.service.http.auth.basic
    Import-Service: com.sun.jes.service.http.auth.basic.BasicSchemeHandler

    There is no limitation to the number of bundles, which can be configured, in a given Application Server.

    Its configuration is specified by a property file named Bundle-Name.properties where Bundle-Name is the name you gave to the bundle in the manifest. Here is an example of configuration:

    cachePath=/jdj
    toTrace=TRUE
    toStat=TRUE
    logfile=/jdj/log.txt
    remoteLocations=/jdj/jdj.properties
    allPermissionPolicy=C:/temp/JES2/allPermission.policy
    defaultPolicy=C:/temp/JES2/default.policy
    keystore=C:/temp/JES2/keystore
    keystorePassword=keystorePswd
    adminUser=admin
    adminPasswd=admin
    ID=Hamlet
    contextPath=/jdj
    useBundleSpace=TRUE
    Diskless=FALSE
    MulticastGroup=228.10.10.10
    MulticastPort=9089
    Multicast=TRUE
    CRLURL=ldap://localhost/CN=alexis,CN=agrandem,CN=CDP,CN=Public Key Services,CN=Services,CN=Configuration,DC=alexis
    CAURL=ldap://localhost/CN=alexis,CN=AIA,CN=Public Key Services,CN=Services,CN=Configuration,DC=alexis
    CRLLDAPuser=Alexis/Users/Administrator
    CRLLDAPpasswd=gunnm007
    CALDAPuser=Alexis/Users/Administrator
    CALDAPpasswd=gunnm007
    expiration=30
    CRLperiod=30

    This file acts as the web.xml of Application Serversí version.
    We bolded the parameters that doesnít exist in web.xml version.

    The package must contain:

    JSPservlet.properties // as the file above
    JSPservletPkg
      CRLchecker.class
      DisklessLog.class
      ICPhandler$DisklessCltHandler.class
      ICPhandler$IcpHeader.class
      ICPhandler$Log.class
      ICPhandler$LogPrivilegedAction.class
      ICPhandler.class
      JSPhandler$ClassEntry$ServletInfo.class
      JSPhandler$ClassEntry$Stat.class
      JSPhandler$ClassEntry.class
      JSPhandler$Log.class
      JSPhandler$Scanner.class
      JSPhandler.class
      JSPloader$ClassInfo.class
      JSPloader$ProtectionDomainInfo.class
      JSPloader$ResourceEntry.class
      JSPloader.class
      JSPloaderException.class
      JSPresourceServlet.class
      ResourcePrivilegedAction.class
      PageBoxAPI.class
      ServletLog.class
      ServletStat.class
      ServletUpdate.class

    We detail below JSPservlet.properties parameters.

    1. cachePath

      cachePath is the location where jars are locally stored after been retrieved from remote location.

      Default value: C:/temp.

    2. toTrace

      Tells if the tool must write diagnostic messages.

      Default value: false.

    3. toStat

      Tells if the tool must record statistics.

      Default value: false.

      If true, statistics are recorded per archive in a file cachePath/archive.stat, which is a property file, for instance:

      #Sun Nov 19 23:20:32 CET 2000
      TestServlet/FileAccess=3
      helloImg=8
      TestServlet/OtherServlet=2
      SnoopJSP=3
      TestServlet/ForwardingServlet=4
      SnoopServlet=2

    4. ID

      Allows the deployer to specify a unique identifier.

      PageBoxAPI allows retrieving this ID.

      Application: deployment of a large number of instances.

      No default value.

    5. logfile

      Tells where the tool must write diagnostic messages.

      Default value: $CachePath/log.txt.

    6. remoteLocations

      Location of a property file containing jar names and associated URLs.

      Default value: $CachePath/$ContextPath.properties where ContextPath indicated the name the war file is deployed with.

      JSPupdate updates this file. It is OK to modify it manually but donít expect to retrieve your comments.

    7. expiration

      You can set this parameter to minimize the round trip number between the browser and the server.

      JSPservlet sets the Expire header field of static content (content with an extension different of class). It computes the Expire as current_time + expiration.

      expiration unit is second.

      Default value: 5 seconds.

    8. contextPath

      contextPath is the equivalent of the name you give to the JSPservletPkg Web Archive in Application Servers configuration.

      Consider you configure JES2 http server to handle requests toward http://myserver:8080, you will invoke a servlet defined in archive myarchive.jar in mypath/myservlet with

      http://myserver:8080/contextPath/myarchive/mypath/myservlet.

      Default: none. Must be specified.

    9. useBundleSpace

      Boolean. If true, uses JES 2 BundleContextís getDataFile to create File objects in the persistent storage area provided for the bundle by the framework.

      We recommend setting it to true first because it is a requirement for well-behaving bundles and second because it provides useful features such as removing all bundle files when the bundle is uninstalled.

      If you set it to true, path parameters are relative to the bundle space root but:

      • allPermissionPolicy
      • defaultPolicy

      The reason is these files must be installed separately and are not related to a bundle.

      Default: true.

    10. Diskless

      Boolean. If true, starts as a diskless client and doesnít write on local file system. In this case, you donít need to set parameters such as logfile and cachePath. If false, starts as a diskless server and writes on local file system for it and its clients.

      Default: false.

    11. Multicast

      Boolean. If true, uses Multicast. In this case, it uses the multicast group specified by MulticastGroup and the port specified by MulticastPort, both for listening and sending.

      If Multicast=false, uses Unicast. In this case, listens on the address specified by MulticastGroup and the port specified by MulticastPort. A diskless client must be configured with two other parameters:

      • RemAddrs contains the IP addresses of diskless servers
      • RemPorts contains the ports of diskless servers

      Default: true.

    12. MulticastGroup

      Specify a valid multicast group with a string xxx.xxx.xxx.xxx, for instance 228.10.10.10 if Multicast=true. Otherwise specifies an IP address or name.

      Default: none. Mandatory.

    13. MulticastPort

      Specify an IP port.

      Default: none. Mandatory.

    14. RemAddrs

      Contains the IP addresses of diskless servers as strings separated by commas, for instance

      Miami, Orlando, Lauderdale.

    15. RemPorts

      Contains the IP ports of diskless servers as strings separated by commas, for instance 9001, 9000, 9002.

      In this example, the diskless client will send messages to Miami:9001, Orlando:9000, Lauderdale: 9002.

    16. allPermissionPolicy

      If it is set, allPermissionPolicy is the path to a policy file with syntax conforming to the Java 2 security specification. If defaultPolicy is also set it means:

      1. JSPservletPkg will implement sandboxes. So every archive will run with the permissions defined either in cachePath/archive.policy or in cachePath/java.policy where:
        • cachePath is the cachePath initialization parameter value
        • archive is the archive name without suffix
      2. The Java server itself will run with the permission described in allPermissionPolicy.

      The following no-brainer allPermissionPolicy will work in all cases:

      grant {
        permission java.security.AllPermission;
      };

      Note that you should never grant permissions in cachePath/archive policy as these files are downloaded from the archive location.

      Default: the parameter has no default value.

    17. defaultPolicy

      If it is set, defaultPolicy is the path to a policy file with syntax conforming to the Java 2 security specification. If allPermissionPolicy is also set it means:

      1. JSPservletPkg will implement sandboxes. So every archive will run with the permissions defined either in cachePath/archive.policy or in cachePath/java.policy where:
        • cachePath is the cachePath initialization parameter value
        • archive is the archive name without suffix
      2. If no policy applies to the archive, then defaultPolicy is used
      3. The Java server itself will run with the permission described in allPermissionPolicy.

      Default: the parameter has no default value.

    18. keystore

      keystore is the name of the key store in cachePath directory, for instance "keystore" but not "/mydir/keystore" or "mydir/keystore".

      If keystore is set, when JSPservletPkg downloads an archive, it tries

      • To download a certificate from the same location as the archive and named archive.cer. If it finds, it adds the certificate to keystore, which has to be in Sun JKS format with an archive alias.
      • To download a permission file from the same location as the archive and named archive.policy. This file should only contain permission entries. JSPservletPkg adds a keystore line, builds the appropriate grant line and stores it in cachePath/archive.policy in order to implement a sandbox with the permissions requested by the provider.

      The archive user has no longer to administrate security. It is appropriate for trusted providers.

      Default: the parameter has no default value.

    19. keystorePassword

      Password JSPservletPkg uses to access the keystore.

      Default: the parameter has no default value.

    20. CAURL

      When JSPservletPkg implements sandboxes, it processes signed archives and retrieve classes certificate chain. If CAURL is set, it connects to this URL and expects to retrieve a Certificate Authority certificate used in the classes certificate chain.

      If it fails to connect to the CA or if what it retrieves is not a certificate, it logs an ERROR entry with "directory access failure". If the certificate is valid but not present in a class certificate chain, it invalidates the class just as if one of its certificates was revoked.

      Note that JSPservletPkg doesnít load the class and therefore doesnít raise a security exception but a class not found exception.

      If you set this parameter, you MUST add JNDI to your Java Server CLASSPATH in JDK 1.2. In JDK 1.3, you donít have to, as JNDI is included in JDK.

      Default: the parameter has no default value.

    21. CRLURL

      When JSPservletPkg implements sandboxes, it processes signed archives and retrieve classes certificates.

      If CRLURL is set, it connects to this URL and expects to retrieve a Certificate Revocation List (CRL) used to check if a class certificate is revoked.

      If it fails to connect to the CA or if what it retrieves is not a CRL, it logs an ERROR entry with "directory access failure". If the CRL is valid and it finds one of the class certificates in it, it invalidates the class.

      Note JSPservletPkg doesnít load the class and therefore doesnít raise a security exception but a class not found exception.

      If you set this parameter, you MUST add JNDI to your Java Server CLASSPATH in JDK 1.2. In JDK 1.3, you donít have to, as JNDI is included in JDK.

      Default: the parameter has no default value.

    22. CALDAPuser

      Principal used to connect to the Directory server to retrieve CAURL.

      Default: the parameter has no default value. If it is not set, the tool connects to the Directory server without credential and password (LDAPpasswd).

    23. CALDAPpasswd

      Password used to connect to the Directory server to retrieve CAURL.

      Default: the parameter has no default value.

    24. CRLLDAPuser

      Principal used to connect to the Directory server to retrieve CAURL.

      Default: the parameter has no default value. If it is not set, the tool connects to the Directory server without credential and password (LDAPpasswd).

    25. CRLLDAPpasswd

      Password used to connect to the Directory server to retrieve CAURL.

      Default: the parameter has no default value.

    26. CRLperiod

      Defines how often the tool will connect to check for CRL updates in seconds.

      Default: 7 * 24 * 3600 (1 week).

  5. Statistics and troubleshooting

    Servlet displaying statistics

    Figure 2: Statistics using ServletStat

    Servlet displaying diskless server log

    Figure 3: log using ServletLog

    You can use the log path that we list at the top of the screen to find out the bundle location.

    However it is not a hidden secret: It starts with the value of com.sun.jes.framework.bundles.baseurl, which is

    D:\Documents and Settings\Administrator\jescache in this case, followed by bundlebundle_id\data, where bundle_id is a number set by the framework.

    ServletLog reads the log file. Log entries not being in memory, it can be used only for diskless servers. To display diskless client logs, you must use DisklessLog and use the URL http://serverURL/DisklessLog. Note that if you have two or more diskless servers on the same subnet, you can choose any of them.

    Then you are prompted to select the appropriate diskless client:

    diskless server servlet use for client log selection

    Figure 4: Selection of the client on DisklessLog

    You select the client and click on List. Then you get the same display as with ServletLog:

    diskless server servlet use for client log display

    Figure 5: Diskless client log display with DisklessLog

    You see the path of the log and clear it.

  6. Notes on implementation

    1. Dynamic update

      Dynamic update of jar file is supported though ServletUpdate.

      ServletUpdate display is split in two sections:

      • A Definition section at the bottom
      • A loaded/defined section at the top, that lists known and loaded archives

      ServletUpdate uses GET mode. It is a servlet defined in the JSPservlet package.

      1. Definition section

        You must fill the JAR Name field without extension. If you donít fill the remote location the current location is reused. It is the JAR file URL minus the file name.

        Assuming you specified a jar name myjar and a remote locationhttp://www.mydownloadsite.com, JSPserletPkg will download http://www.mydownloadsite.com/myjar.jar and persist your action in RemoteLocations with a property myjar=http://www.mydownloadsite.com.

        Note the URL of ServletUpdate http://localhost:6080/jdj/JSPupdate. jdj is the contextPath. If you deploy different JSPservlet bundles, you must select the appropriate JSPservlet to require an update. When you updates, the local cache is removed and the jar is always loaded from the remote location. You can also use ServletUpdate to add a jar.

        Web archive creation in servlet

        Figure 6: ServletUpdate definition

      2. Loaded/defined section

        Web archive update and delete in servlet

        Figure 7: ServletUpdate list

        It supports a trace checkbox and two buttons:

        • If trace is checked, it means that trace is on.
        • Upd in the Loaded/define section means:
          • Download a new version of the archive in the cache
          • Replace current loaded version of classes and resources
        • Del in the Loaded/define section means:
          • Remove the archive from the cache
          • Remove the archive servlets, classes and resources from memory

        You can safely require an update when pages are accessed.

        GC allows to invoke System.gc() in the Java server context.

    2. Resource handling

      Typical case of that is image handling.

      Suppose a JSP whose URL is http://www.mysite.com/jdj/myjar/myJSP references an image with a relative path images/myimage.gif. The Application Server looks for http://www.mysite.com/jdj/myjar/images/myimage.gif and therefore invokes JSPresourceServlet.

      JSPresourceServlet looks first for images/myimage.gif in the archive. If it doesnít find it, it retrieves the download location in the myjarís RemoteLocations property. If it finds its remote location is www.mydownloadsite.com, it downloads the image from www.mydownloadsite.com/images/myimage.gif.

  7. Special cases

    1. RequestDispatcher

      The only case where you must modify your code is when you need using a RequestDispatcher either to include or forward a request. You can use JSPservlet.getJAR() helper function.

      RequestDispatcher rd = getServletContext().getRequestDispatcher(JSPservlet.getJAR(getClass().getClassLoader()) + OtherServlet);

      The reason is that as a servlet developer you should not hardcode neither the Web Application name as the standard enforces it, neither the jar name where your servlet will be deployed.

    2. Use of SSL

      JSPservlet allows using SSL to download archives using the ssl.jar bundle.

      The explanation below is not JSPservlet related but it still can help you to configure SSL. As it can fail at your first attempt, we recommend you reading the JSSE API user guide. It explains you how to trace the SSL connection with javax.net.debug=all and gives you a lot of information.

      You need first to SSL enable the Web Server where you download the archive from. It implies generating a key pair. The server keeps the private key internally and asks you to submit a certificate request to the Certificate Authority of your choice.

      During the SSL handshaking, jsse will check it knows the certificate chain the Web Server presents it using the keystore specified by com.sun.jes.impl.keystore.store. A default keystore is defined in JES installation path/lib/tlscerts.

      tlscerts format is jks, which means you can use keytool to display or update its content.

      If the server Certificate Authority certificate is not in the list, you have to add it.

      Retrieving it depends on the browser and on the Certificate Authority. You can ask for a DER encoded or for a base 64 format.

      Then you can add your server certificate with:

      keytool -import -file C:\TEMP \serverCA.cer -alias myCA -keystore <JES2-home>/lib/tlscerts -storepass passphrase

    3. Load test

      With up to 3000 servlets in a single jar file.

      The performance impact of tracing is below 10%.

      The sandbox performance impact is not measurable.

    4. Functional tests

      1. Update

        ServletUpdate

        Multiple archives, multiple web applications

        Invalid archive name/location

      2. Security

        Non-signed archive

        • without sandbox
        • with sandbox and no definition in policy file
        • with sandbox and permissions granted in policy file.

        Signed archive with and without sandbox. With sandbox:

        • Valid certificate
        • Certificate not found in CA
        • Revoked certificate
        • Uncheckable archive
        • CAURL not set or not accessible
        • CRLURL not set or not accessible
        • Revocation when the server is running

        1 policy file per web application or 1 per archive.

        No permission granted to a signed archive.

        Policy/certificate download

      3. Misc
        • Image handling
        • Beans handling
        • Servlet inheritance
        • Servlet/html include and forward
        • Caching
        • JSPservletPkg defined in CLASSPATH
        • https for download
  8. Limitations

    We checked the tool supports:

    • Servlet inheritance, case where you define a servlet as extending a base servlet.
    • Tag libs
    • JSP beans. Note however a bean is created with Beans.instantiate(). This method tries to restore the bean from a bean.ser resource and if it doesnít find it, it creates it using newInstance(). The tool searches the resource first in the archive, next in the same remote directory as the archive and finally asks the resource to the application server.

    Limitations can be:

    1. Though it supports the Tomcat jspc servlet compiler, JES 2 doesnít support taglib. If you need it you have to add it yourself
    2. HttpJspBase.getClassLoader() doesnít return the JSPservlet class loader that knows how to find bean classes and serialized files

    We chose using Sun packages as much as possible.

    1. We used the tcatjspcruntime bundle to provide basic JSP support.
    2. We created a tagext bundle to add tag support. The purpose of this package is to export javax.servlet.jsp.tagext package that we extracted from Tomcatís servlet.jar. We defined a minimal bundle activator:
    3. public class TagextActivator implements BundleActivator {
        public void start(BundleContext bundlecontext) {}
        public void stop(BundleContext bundlecontext) {}
        public TagextActivator() {}
      }

      We packaged the bundle with this manifest:

      Manifest-Version: 1.0
      Bundle-Vendor: apache.org
      Bundle-Version: 1.0
      Bundle-Activator: tagext.TagextActivator
      Bundle-DocURL: http://jakarta.apache.org
      Created-By: 1.2.2 (Sun Microsystems Inc.)
      Bundle-Name: tagext
      Bundle-ContactAddress: agrandemange@pagebox.net
      Export-Package: javax.servlet.jsp.tagext
      Bundle-Description: tag extension
      Import-Package: javax.servlet,javax.servlet.jsp,javax.servlet.http,org.apache.jasper,org.apache.jasper.runtime

    4. It is not enough because taglibs have exceptions, JspTagException that inherits from JspException, defined in javax.servlet.jsp but not in tcatjspcruntime. we chose adding them to JSPservlet package.
    5. We replaced Beans.instantiate(getClassLoader(), myBean) by Beans.instantiate(getClass().getClassLoader(), myBean) in compiled JSPs.
    6. You can consider an alternate solution where you add the JSP related stuff to JSPservlet.

  9. Differences between Application Server, JES 2 and diskless versions

    Application Server version supports Servlet 2.2.

    JES 2 version supports JES 2 Servlet 2.1.

    Diskless version is a superset of JES 2 support with a support for diskless - ROM able - clients.

    All versions should follow closely framework versions in the future.

    The major design difference is between JES/diskless and Application Server version:

    • In the application server version, a service servlet, JSPservlet forwards requests to the target servlet
    • In the JES2 version, the package registers every servlet in the framework. The service servlet, JSPresourceServlet handles only resources.
    • As a consequence, JES 2 framework invokes directly the target servlets.

    This has two important implications:

    1. In case of archive update, there is no window where a request should hang but there is a window where a request can fail because the previous servlet version was unregistered and the new version was not yet registered.
    2. If an archive certificate is revoked, you need to update the archive or restart the server for the revocation to be detected.

    We chose to design the JES 2 version in that way to minimize its footprint.

    Diskless version is close to JES 2 version because differences are hidden in

    • Initialization
    • Logging method implementation
    • Periodic checks

    This code makes however a difference in term of footprint - 40% bigger. We maintain JES 2 version mainly for that reason.

  10. Miscellaneous
    1. License

      This program is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; version 2.1 of the License.

      This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

    2. Deliveries

      Package name: JSPLoaderPkg.

      Source files:

      CRLchecker.java JNDI/LDAP code
      DisklessLog.java Servlet to display diskless client logs on diskless server side
      ICPhandler.java ICP message handler
      JSPloader.java class loader
      JSPloaderException.java package exception
      JSPhandler.java Web application handler
      JSPresourceServlet.java Resource handling servlet
      PageBoxAPI.java API to get the PageBox ID and log user messages
      ResourcePrivilegedAction.java resource loader
      ServletLog.java servlet to clear and display log
      ServletStat.java servlet to display stats
      ServletUpdate.java update servlet

      Documentation:

      • This document
      • javadoc

Installation Constellations Versions Demo
Publisher Mapper Cocoon/SOAP Security Configurator
J2EE version Embedded version Diskless version

Contact:support@pagebox.net
©2001-2004 Alexis Grandemange   Last modified