Version 5

    Enhancements to the MainDeployer SuffixOrder mechanism


    Note that this applies to versions starting with 4.0.1


    The Case


    For the motivation, see the

    forums. The point is

    to allow deployers to dynamically add their suffixes (e.g. "aop") to the

    MainDeployer's and the Scanners DeploymentSorter.


    We build on this case in order to provide for:

    1. The externalization of all SuffixOrder configuration info

    2. The automatic addition/removal of Suffixes in the correct order

    3. The overriding of SuffixOrder through the MainDeployer, if needed.


    The Changes




    The SubDeployer interface and the supporting base class SubDeployerSupport

    have two extra read/write attributes, inherited to all SubDeployers:


    • Suffixes (String{FOOTNOTE DEF  }) - used to specify the suffixes of interest to

      a particular SubDeployer, e.g. for AspectDeployer it is "aop" & "aop.xml"

    • RelativeOrder (int) - used to assign an arbitrary relative order value

      to the above suffixes, e.g. for AspectDeployer we chose a default

      value of "100".


    The RelativeOrder is just a way to order the SubDeployer suffixes

    in the server's DeploymentSorter used by the MainDeployer and the

    Scanner. Their suffixes are sorted according to their relative order

    value when their are added to the master SuffixOrder list.

    So a suffix with a relative order "100" is added before

    a suffix with a relative order "101" or higher, but after any

    existing suffix of value "100" or lower.


    The SubDeployers don't need to do anything else (like set the

    MainDeployer's SuffixOrder as before), apart from optionally

    specifying a sensible initial value for those 2 attributes

    (e.g. inside a default constructor).


    I've already done so the following SubDeployers in the sense that

    those are the most likely to be dynamically added or removed from

    a running server:


    1. AspectDeployer - "aop", "aop.xml", relative order: 100

    2. HARDeployer - "har", relative order:400

    3. EJB3Deployer, "ejb3", relative order:500

    4. BeanShellSubDeployer, "bsh", relative order:800




    The MainDeployer maintains its SuffixOrder (String{FOOTNOTE DEF  }) attribute as before,

    although the attribute is now read-only and it reflects at any given point

    the master suffix order list used by the MainDeployer and the Scanner.


    The SuffixOrder attribute gets its initial value from a new

    EnhancedSuffixOrder (String{FOOTNOTE DEF  }, read/write) attribute that can be set

    in ./conf/xmdesc/org.jboss.deployment.MainDeployer-xmbean.xml.


    The implicit initial value of this attribute, is:




    It basically provides a fixed SuffixOrder list, enhanced with

    relative order values for each suffix. Those values cannot change

    from registering SubDeployers.


    Whenever a SubDeployer registers with the MainDeployer, the latter will

    query its Suffixes and RelativeOrder attributes, and if they are set

    (e.g. "aop", "aop.xml", 100) the MainDeployer will update the SuffixOrder

    value with the new suffixes in the correct order, unless the suffixes

    are already in the SuffixOrder array, in which case they are ignored.


    Upon deregistration of a SubDeployer, it's suffixes are removed,

    unless they were specified in the initial EnhancedSuffixOrder setting

    (which means they are fixed).


    The choise of relative order values is arbitrary, however, using the above

    setting we essentially achieve the same SuffixOrder as before, only

    in a more dynamic and configurable way.


    Referenced by: