All Packages  This Package  Class Hierarchy  Class Search  Index

java.lang.Object
   |
   +----edu.utah.janos.ants.ants.Capsule
           |
           +----edu.utah.janos.ants.ants.DLResponseCapsule

Summary

public class  DLResponseCapsule
     extends edu.utah.janos.ants.ants.Capsule
{
          // Fields 11
     static final byte[] MID;
     private static final byte[] PID;
     public static final String VERSION;
     private int chunkMask;
     private int clen;
     private ByteArray code;
     private int coff;
     private TypeID groupID;
     private TypeID[] groups;
     private String name;
     private TypeID payloadID;

          // Constructors 2
     DLResponseCapsule();
     DLResponseCapsule(CapsuleClass, int, int, int);

          // Methods 6
     public Xdr decode();
     public Xdr encode();
     public boolean evaluate(Node);
     public int length();
     protected byte[] mid();
     protected byte[] pid();
}

Demand Load Response capsule. DLResponseCapsules are only created by a DLRequestCapsule that has been delivered to a node that can satisfy the request. DLResponseCapsules contain a single "chunk" of a CodeGroup.

A DLResponseCapsule packet contains the following fields (on top of the base Capsule fields):

• payloadID: the TypeID of the CapsuleClass for which this DLResponseCapsule holds code.
• groupID: the TypeID of the CodeGroup to which this DLResponseCapsule's CapsuleClass should be added.
• array len: the length of the array (next entry) (short).
• Array of groupIDs: the TypeIDs of the other CodeGroup's in the Protocol to which this DLResponseCapsule will be added.
• chunkMask: the chunk in the CodeGroup's chunk list which this DLResponseCapsule provides.
• clen: the length of this chunk (int, could be short) (could be nuked, implicit in packet length)
• coff: the offset of this chunk in the CapsuleClass's code array. (int, could be short).
• name: A string name of the CapsuleClass this DLResponseCapsule represents.
• code: the chunk itself.
Author:
David Wetherall

See Also: DLProtocol, DLRequestCapsule, CodeGroup

Fields

· VERSION

Summary  |  Top

   public static final String VERSION

   static final byte[] MID

   private static final byte[] PID

   private TypeID payloadID

The MID of the CapsuleClass owning the chunk this capsule contains.

   private TypeID groupID

The GID of the CodeGroup this chunk belongs to.

   private TypeID[] groups

The GID of every other CodeGroup in the Protocol this CodeGroup is part of. This is the only way a CodeGroup can compute its ProtocolID.

XXX seems like it would be more efficient to just send the ProtocolID across the wire and double check it after the CodeGroup is loaded. XXX Probably a security concern.

   private int chunkMask

The mask containing only the index of the chunk (in the CodeGroup's chunkmask) contained in this Capsule.

   private int clen

Length of the full bytecode for the Class.

   private int coff

Offset of this chunk in the CapsuleClass's code block.

   private String name

Name of the CapsuleClass this chunk represents.

XXX Only needs to be in the first chunk for a class.

   private ByteArray code

The chunk.

Constructors

· DLResponseCapsule

Summary  |  Top

   DLResponseCapsule() 

Construct a blank DLResponseCapsule.

This is only invoked when a DLResponseCapsule capsule is received at a node and the node must construct a capsule before decoding the packet into it.

   DLResponseCapsule(CapsuleClass cc, 
                     int idx, 
                     int pos, 
                     int len) 

Construct a DLResponseCapsule that will contain the given chunk of the given method. Only invoked by DLRequestCapsule.evaluate().

Parameter	Description
m	The method which is being sent.
idx	the chunk id
pos	the position in the method's class file of the chunk start
len	the size of the chunk (<= CodeGroup.CHUNK_SIZE)

See Also: evaluate

   protected byte[] mid() 

Overrides:

mid in class Capsule

   protected byte[] pid() 

Overrides:

pid in class Capsule

   public int length() 

Overrides:

length in class Capsule

   public Xdr encode() 

Overrides:

encode in class Capsule

   public Xdr decode() 

Overrides:

decode in class Capsule

   public boolean evaluate(Node node) 

Evalute a DLResponseCapsule at this node. Looks up the appropriate CapsuleClass and CodeGroup info, creating new ones if necessary.

XXX should deal with unanticipated DLResponseCapsules better.

Overrides:

evaluate in class Capsule

All Packages  This Package  Class Hierarchy  Class Search  Index