<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<!--NewPage-->
<html>
<head>
<!-- Generated by javadoc on Wed Jul 28 01:21:15 GMT 1999 -->
<title>
  Interface java.rmi.dgc.DGC
</title>
</head>
<body>
<a name="_top_"></a>
<pre>
<a href="packages.html">All Packages</a>  <a href="tree.html">Class Hierarchy</a>  <a href="Package-java.rmi.dgc.html">This Package</a>  <a href="Package-java.rmi.dgc.html">Previous</a>  <a href="Package-java.rmi.dgc.html">Next</a>  <a href="AllNames.html">Index</a></pre>
<hr>
<h1>
  Interface java.rmi.dgc.DGC
</h1>
<dl>
  <dt> public interface <b>DGC</b>
  <dt> extends <a href="java.rmi.Remote.html#_top_">Remote</a>
</dl>
The DGC abstraction is used for the server side of the distributed
 garbage collection algorithm. This interface contains the two
 methods: dirty and clean. A dirty call is made when a remote
 reference is unmarshaled in a client (the client is indicated by
 its VMID). A corresponding clean call is made when no more
 references to the remote reference exist in the client. A failed
 dirty call must schedule a strong clean call so that the call's
 sequence number can be retained in order to detect future calls
 received out of order by the distributed garbage collector.
 A reference to a remote object is leased for a period of time by
 the client holding the reference. The lease period starts when the
 dirty call is received. It is the client's responsibility to renew
 the leases, by making additional dirty calls, on the remote
 references it holds before such leases expire. If the client does
 not renew the lease before it expires, the distributed garbage
 collector assumes that the remote object is no longer referenced by
 that client.
<p>
<hr>
<a name="index"></a>
<h2>
  <img src="images/method-index.gif" width=207 height=38 alt="Method Index">
</h2>
<dl>
  <dt> <img src="images/red-ball-small.gif" width=6 height=6 alt=" o ">
	<a href="#clean(java.rmi.server.ObjID[], long, java.rmi.dgc.VMID, boolean)"><b>clean</b></a>(ObjID[], long, VMID, boolean)
  <dd>  The clean call removes the 'vmid' from the reference list of
 each remote object indicated in 'id's.
  <dt> <img src="images/red-ball-small.gif" width=6 height=6 alt=" o ">
	<a href="#dirty(java.rmi.server.ObjID[], long, java.rmi.dgc.Lease)"><b>dirty</b></a>(ObjID[], long, Lease)
  <dd>  The dirty call requests leases for the remote object references
 associated with the object identifiers contained in the array
 'ids'.
</dl>
<a name="methods"></a>
<h2>
  <img src="images/methods.gif" width=151 height=38 alt="Methods">
</h2>
<a name="dirty(java.rmi.server.ObjID[], long, java.rmi.dgc.Lease)"><img src="images/red-ball.gif" width=12 height=12 alt=" o "></a>
<a name="dirty"><b>dirty</b></a>
<pre>
 public abstract <a href="java.rmi.dgc.Lease.html#_top_">Lease</a> dirty(<a href="java.rmi.server.ObjID.html#_top_">ObjID</a> ids[],
                             long sequenceNum,
                             <a href="java.rmi.dgc.Lease.html#_top_">Lease</a> lease) throws <a href="java.rmi.RemoteException.html#_top_">RemoteException</a>
</pre>
<dl>
  <dd> The dirty call requests leases for the remote object references
 associated with the object identifiers contained in the array
 'ids'. The 'lease' contains a client's unique VM identifier (VMID)
 and a requested lease period. For each remote object exported
 in the local VM, the garbage collector maintains a reference
 list-a list of clients that hold references to it. If the lease
 is granted, the garbage collector adds the client's VMID to the
 reference list for each remote object indicated in 'ids'. The
 'sequenceNum' parameter is a sequence number that is used to
 detect and discard late calls to the garbage collector. The
 sequence number should always increase for each subsequent call
 to the garbage collector.
 Some clients are unable to generate a VMID, since a VMID is a
 universally unique identifier that contains a host address
 which some clients are unable to obtain due to security
 restrictions. In this case, a client can use a VMID of null,
 and the distributed garbage collector will assign a VMID for
 the client.
 The dirty call returns a Lease object that contains the VMID
 used and the lease period granted for the remote references (a
 server may decide to grant a smaller lease period than the
 client requests). A client must use the VMID the garbage
 collector uses in order to make corresponding clean calls when
 the client drops remote object references.
 A client VM need only make one initial dirty call for each
 remote reference referenced in the VM (even if it has multiple
 references to the same remote object). The client must also
 make a dirty call to renew leases on remote references before
 such leases expire. When the client no longer has any
 references to a specific remote object, it must schedule a
 clean call for the object ID associated with the reference.
<p>
</dl>
<a name="clean(java.rmi.server.ObjID[], long, java.rmi.dgc.VMID, boolean)"><img src="images/red-ball.gif" width=12 height=12 alt=" o "></a>
<a name="clean"><b>clean</b></a>
<pre>
 public abstract void clean(<a href="java.rmi.server.ObjID.html#_top_">ObjID</a> ids[],
                            long sequenceNum,
                            <a href="java.rmi.dgc.VMID.html#_top_">VMID</a> vmid,
                            boolean strong) throws <a href="java.rmi.RemoteException.html#_top_">RemoteException</a>
</pre>
<dl>
  <dd> The clean call removes the 'vmid' from the reference list of
 each remote object indicated in 'id's.  The sequence number is
 used to detect late clean calls.  If the argument 'strong' is
 true, then the clean call is a result of a failed dirty call,
 thus the sequence number for the client 'vmid' needs to be
 remembered.
<p>
</dl>
<hr>
<pre>
<a href="packages.html">All Packages</a>  <a href="tree.html">Class Hierarchy</a>  <a href="Package-java.rmi.dgc.html">This Package</a>  <a href="Package-java.rmi.dgc.html">Previous</a>  <a href="Package-java.rmi.dgc.html">Next</a>  <a href="AllNames.html">Index</a></pre>
</body>
</html>
