[FAB-4098], [FAB-5041], [FAB-9055] Glossary updates

Add/improve defs for consortium,
organization, member, anchor peer
and ledger

Change-Id: Iba7cf2499840e672cb5af169ffe74e83bbd958a8
Signed-off-by: pama-ibm <pama@ibm.com>
Signed-off-by: joe-alewine <Joe.Alewine@ibm.com>

Author: pamandrejko

docs/source/glossary.rst

@@ -1,4 +1,3 @@
-*Needs Review*
 
 Glossary
 ===========================
@@ -13,11 +12,15 @@ read the entire thing in one sitting if you like; it's pretty enlightening!
 Anchor Peer
 -----------
 
-A peer node on a channel that all other peers can discover and communicate with.
-Each Member_ on a channel has an anchor peer (or multiple anchor peers to prevent
-single point of failure), allowing for peers belonging to different Members to
-discover all existing peers on a channel.
-
+Anchor peers are used to bootstrap gossip communication between peers from
+different organizations. Cross-organization gossip is scoped to channels. In
+order for cross-org gossip to work, peers from one org need to know at
+least the address of a peer from another organization in the channel.
+Each organization added to a channel should identify at least one of its
+peers as an anchor peer. The anchor peer address is stored in the
+configuration block of the channel. Each organization that has a peer
+should have at least one (there can be more than one) of its peers
+defined as an anchor peer.
 
 .. _Block:
 
@@ -100,6 +103,18 @@ A broader term overarching the entire transactional flow, which serves to genera
 an agreement on the order and to confirm the correctness of the set of transactions
 constituting a block.
 
+.. Consortium
+
+Consortium
+----------
+
+A consortium is a collection of non-orderer organizations on the blockchain
+network. These are the organizations that form and join channels and that own
+peers. While a blockchain network can have multiple consortia, most blockchain
+networks have a single consortium. At channel creation time, all organizations
+added to the channel must be part of a consortium. However, an organization
+that is not defined in a consortium may be added to an existing channel.
+
 .. _Current-State:
 
 Current State
@@ -229,16 +244,28 @@ channel, who then distribute them to other peers within the same member cluster.
 Ledger
 ------
 
-A ledger is a channel's chain and current state data which is maintained by each
-peer on the channel.
+A ledger consists of two distinct, though related, parts -- a "blockchain" and
+the "state database", also known as "world state". Unlike other ledgers,
+blockchains are **immutable** -- that is, once a block has been added to the
+chain, it cannot be changed. In contrast, the "world state" is a database
+containing the current value of the set of key-value pairs that have been added,
+modified or deleted by the set of validated and committed transactions in the
+blockchain.
+
+It's helpful to think of there being one **logical** ledger for each channel in
+the network. In reality, each peer in a channel maintains its own copy of the
+ledger -- which is kept consistent with every other peer's copy through a
+process called **consensus**. The term **Distributed Ledger Technology**
+(**DLT**) is often associated with this kind of ledger -- one that is logically
+singular, but has many identical copies distributed across a set of network
+nodes (peers and the ordering service).
 
 .. _Member:
 
 Member
 ------
 
-A legally separate entity that owns a unique root certificate for the network.
-Network components such as peer nodes and application clients will be linked to a member.
+See Organization_.
 
 .. _MSP:
 
@@ -277,6 +304,21 @@ designed to support pluggable implementations beyond the out-of-the-box SOLO and
 The ordering service is a common binding for the overall network; it contains the cryptographic
 identity material tied to each Member_.
 
+.. _Organization:
+
+Organization
+-----------------
+Also known as "members", organizations are invited to join the blockchain network
+by a blockchain service provider. An organization is joined to a network by adding its
+Membership Service Provider (MSP_) to the network. The MSP defines how other members of the
+network may verify that signatures (such as those over transactions) were generated by a valid
+identity, issued by that organization. The particular access rights of identities within an MSP
+are governed by policies which are are also agreed upon when the organization is joined to the
+network. An organization can be as large as a multi-national corporation or as small as an
+individual. The transaction endpoint of an organization is a Peer_. A collection of organizations
+form a Consortium_. While all of the organizations on a network are members, not every organization
+will be part of a consortium.
+
 .. _Peer:
 
 Peer