Opinions on migration to Java EE

Discussion in 'Java' started by patricia.joyces@gmail.com, Jul 27, 2008.

  1. Guest

    Hi there,
    I want to get your opinion on this. I have a web application that runs
    on Tomcat. This has been running smoothly for a number of years. I
    would like to migrate this web application to Java EE platform, to be
    hosted on an app server like Oracle App Server or any other products.
    If you have done this before, can you please share your migration
    experiences, like what to look out for, migraton steps, information
    links, etc. Any help would be appreciated. Thanks.
    , Jul 27, 2008
    #1
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  2. Arne Vajhøj Guest

    wrote:
    > I want to get your opinion on this. I have a web application that runs
    > on Tomcat. This has been running smoothly for a number of years. I
    > would like to migrate this web application to Java EE platform, to be
    > hosted on an app server like Oracle App Server or any other products.
    > If you have done this before, can you please share your migration
    > experiences, like what to look out for, migraton steps, information
    > links, etc.


    An app running on Tomcat is a Java EE app.

    Tomcat only support the web part of Java EE, but Oracle AS
    supports everything including EJB's.

    But your app should run unchanged on Oracle AS.

    If you don't change you app, then your will obviously
    not utilize the features Oracle AS has that Tomcat does not.

    Arne
    Arne Vajhøj, Jul 27, 2008
    #2
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  3. <> wrote in message
    news:...
    > Hi there,
    > I want to get your opinion on this. I have a web application that runs
    > on Tomcat. This has been running smoothly for a number of years. I
    > would like to migrate this web application to Java EE platform, to be
    > hosted on an app server like Oracle App Server or any other products.
    > If you have done this before, can you please share your migration
    > experiences, like what to look out for, migraton steps, information
    > links, etc. Any help would be appreciated. Thanks.


    From the pure functionality viewpoint, an obvious early step is to make sure
    that app server X supports the Java language version and the J2EE API
    versions you are using.

    Be prepared to play with libraries. If you are using Apache XML libraries in
    your Tomcat webapp, you may want to stick with them, for example. I brought
    this one up because evidently quite a few people have had problems in this
    area with OAS. See
    http://www.oracle.com/technology/tech/java/oc4j/1013/how_to/how-to-swapxmlparser/doc/readme.html
    for OAS; whether or not this is applicable will depend on OC4J version.

    There may be similar issues with any server -> other server migration. In a
    perfect world libraries written to certain APIs are cleanly swappable - in
    the real world they are not. Part of the reason is partial support or
    differing interpretations of the APIs.

    Other things to look out for, particularly with an older application. One,
    use of server-specific APIs to make up for stuff that J2EE didn't do at the
    time, or wasn't standardized. Two, non-portable code (things like embedded
    references). Non-portable code may come about because of use of vendor APIs
    or how you use J2EE APIs (like JDBC).

    Look at what you needed to configure on Tomcat - usernames/passwords/roles
    etc, JNDI, JDBC, you name it - and figure out how that'll be done on the
    target server.

    Last but not least, other people have done it before. Googling will dredge
    up posts regarding specific issues you run into, and the odds are also
    pretty good that there will be a migration guide or guides (sometimes as
    specific as Server A to Server B).

    Arne and Lew are quite correct insofar as this may be fairly painless. But I
    wouldn't go telling your boss that you'll be done with the migration in a
    couple of hours either. :)

    AHS
    Arved Sandstrom, Jul 27, 2008
    #3
  4. On 27.07.2008 15:17, wrote:
    > Hi there,
    > I want to get your opinion on this. I have a web application that runs
    > on Tomcat. This has been running smoothly for a number of years. I
    > would like to migrate this web application to Java EE platform, to be
    > hosted on an app server like Oracle App Server or any other products.
    > If you have done this before, can you please share your migration
    > experiences, like what to look out for, migraton steps, information
    > links, etc. Any help would be appreciated. Thanks.


    Why do you want to do this? Why change a system that apparently works
    as expected? You give no indication why you intend to migrate to Java
    EE (which, in a way, you are using already as has been pointed out) so
    for the time being I'd say, don't do it.

    Cheers

    robert
    Robert Klemme, Jul 27, 2008
    #4
  5. Markus Tazl Guest

    On 27 Jul., 15:17, wrote:
    > Hi there,
    > I want to get your opinion on this. I have a web application that runs
    > on Tomcat. This has been running smoothly for a number of years. I
    > would like to migrate this web application to Java EE platform, to be
    > hosted on an app server like Oracle App Server or any other products.
    > If you have done this before, can you please share your migration
    > experiences, like what to look out for, migraton steps, information
    > links, etc. Any help would be appreciated. Thanks.


    Hi Particia,

    i'm curious about why you want to do this ? Any additional
    requirements you can't meet using Tomcat ?

    Anyway, i use Oracle IAS / OC4J and Tomcat 5.x. in my projects and i
    also did some migration work in both directions. As Arved mentioned
    there might be some minor pitfalls regarding libraries, JNDI and so
    on. Migration from Tomcat to OC4J should be more or less painless.
    On technet / Oracle online documentation there are some hints, you can
    find "Oracle® Containers for J2EE Servlet Developer's Guide" /
    "Migrating an Application from Apache Tomcat to OC4J" here :
    http://download.oracle.com/docs/cd/B32110_01/web.1013/b28959/develop.htm#CHDFJJDA

    best regards
    Markus Tazl
    Markus Tazl, Jul 27, 2008
    #5
  6. Arne Vajhøj Guest

    Robert Klemme wrote:
    > On 27.07.2008 15:17, wrote:
    >> Hi there,
    >> I want to get your opinion on this. I have a web application that runs
    >> on Tomcat. This has been running smoothly for a number of years. I
    >> would like to migrate this web application to Java EE platform, to be
    >> hosted on an app server like Oracle App Server or any other products.
    >> If you have done this before, can you please share your migration
    >> experiences, like what to look out for, migraton steps, information
    >> links, etc. Any help would be appreciated. Thanks.

    >
    > Why do you want to do this? Why change a system that apparently works
    > as expected? You give no indication why you intend to migrate to Java
    > EE (which, in a way, you are using already as has been pointed out) so
    > for the time being I'd say, don't do it.


    One reason could be server consolidation.

    He can run the Tomcat apps at Oracle AS. He can probably not run
    the Oracle AS apps on Tomcat.

    Arne
    Arne Vajhøj, Jul 27, 2008
    #6
  7. wrote:
    > Hi there,
    > I want to get your opinion on this. I have a web application that runs
    > on Tomcat. This has been running smoothly for a number of years. I
    > would like to migrate this web application to Java EE platform, to be
    > hosted on an app server like Oracle App Server or any other products.
    > If you have done this before, can you please share your migration
    > experiences, like what to look out for, migraton steps, information
    > links, etc. Any help would be appreciated. Thanks.

    In addition to ensuring things like not using app server specific
    libraries and ensuring that the server supports the specification
    versions you are using,

    * developers sometimes make subtle assumptions about where and what kind
    of environment the code is running in. For example, (an incorrect?) use
    of meta information to figure out system paths, loading property files
    and doing funky ("the so called clever") things with the classloading
    can create problems so you want to review your code for resource and
    class loading code.
    * If you are not already running in a clustered environment, you could
    have code for accessing file system which may not work in a different
    app server. So you want to do a code review for file system access as well.
    * Security (specially authentication and authorization) plugins can be
    very different although you should be OK if you are using JAAS.
    * Using MBeans in tomcat could also be a bit of a problem.

    Abhijat
    Abhijat Vatsyayan, Jul 29, 2008
    #7
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