Key elements are annotatedSome of these elements are:

1. 87a0a8c7505d64 refers to root node UUID

2. The grayed out text refers to Modeshape classes responsible for data representation and serialization. The JBoss Marshalling serialization format contains the name of datastructures i.e. custom marshallers in org.infinispan.schematic.internal.* 

3. Node name.

4. The file contains binary data for specifying different internal attributes, so

   the file

   when opened up in an ordinary text editor, the text editor might show some numbers as garbage characters

   or numbers in strings. /children0<key87a0a8c317f1e7jcr:systemnamejcr:system1Skey387a0a8c7505d64 . Similarly, if object 'chandni' had siblings, the array would appear in the binary as:
5. Name/string (53f49a07-8e14-41a1-bab3-abc59d86846enamechandni)

Similary, for the datastream:

1. . These numbers have meaning for node's attributes, though. For example, the highlighted entry #4 specifies an array of the children of a node. The index number of the child precedes its key and name. So, if object "greetings_en" gets another sibling "greetings_fr", the latter's entry would be preceded by 2 (its index). The full children node array would now appear something like: 

   /children0<key87a0a8c317f1e7jcr:systemnamejcr:system 1Xkey387a0a8c7505d6417c366d9-25bc-4e2d-9e53-4428fe7b8152namegreetings_en 2Xkey387a0a8c7505d64aa21b2ee-d22a-4b0a-8b43-a8e8b58c5ec6namegreetings_fr

2. Children count in binary.

Similarly, for the datastream content (omitting ModeShape API artifacts):

Some of the elements of interests are:

1. Root UUID
2. Omitted Serialization artifacts (see note on parent node for details).
3. UUID
4. Content type of document (in this case it's the default content type for documents).
5. Parent UUID (datastream)
6. Actual content ("hello world" text in this case).
7. Last modified date.
8. Last modified admin. 
9. Content type of datastream.
10. SHA-1 generated by Fedora.
    
    

Inspecting Indexing Folder

ModeShape currently makes use of Hibernate Search to manage Lucene indexes. The indexes can be viewed by using Luke, e.g.
These files can be found in the "fcrepo.modeshape.index.location" directory. 

Image Added

Inspecting ObjectStore Folders

Directories "com.arjuna.ats.arjuna.objectstore.objectStoreDir" and "com.arjuna.ats.arjuna.common.ObjectStoreEnvironmentBean.default.objectStoreDir" are JBoss JTA transaction engine artifacts. The default Fedora Infinispan configuration attempts to find a JBossJTA transaction manager implementation via  "org.infinispan.transaction.lookup.GenericTransactionManagerLookup". This configuration uses Arjuna ShadowFileStore as a backend, resulting in several directories within fcrepo4-data such as "object-store" and "object-store-default":

   |-object-store
   |---ShadowNoFileLockStore
   |-----defaultStore
   |-------Recovery
   |---------TransactionStatusManager
   |-object-store-default
   |---ShadowNoFileLockStore
   |-----defaultStore

A detailed description of the artifacts maintained by the JBossJTA implementation is most likely beyond the scope of this document (at least for now).

Infinispan Configuration Options

Depending on the configured Infinispan backend, the directory layout and contents of the binary files would be different. The following sections covers other cache store options.

File system Backends

LevelDB Backend

Currently, the default configuration outputs Fedora data to LevelDB (a fast filesystem based key-value store). When Fedora 4 is started, ModeShape (actually Infinispan and LevelDB in the background) will create several directories on the filesystem. Currently, the directories created are:

...

1. File .log holds entries for recent transactions. The relevant API for representing these entries is modeshape-schematics (see, e.g.,  org.infinispan.schematic.SchematicEntry)
2. File .sst stores these entries when the .log file reaches a size threshold. A new log file is generated.
3. File MANIFEST.x records info about .sst files (among other things). 
4. File CURRENT specifies the current MANIFEST file.

Most of these files are binary and can be read by a LevelDB Java library.

Inspecting Individual Binary Data Files

As is the case with the FileCacheStore, the .log files are binary. The default initial .log file is 000003.log, and it contains serialized entries for all the nodes from recent transactions. If the repository has only a few hundred added nodes, this file will contain all the nodes (i.e. the additions and default properties like mix:etag).