Blob Inspector

There are many benefits to having a custom binary serialization format (see Object serialization for details) but one disadvantage is the inability to view the contents in a human-friendly manner. The Corda Blob Inspector tool alleviates this issue by allowing the contents of a binary blob file (or URL end-point) to be output in either YAML or JSON. It uses JacksonSupport to do this (see JSON).

The tool is distributed as part of Corda Enterprise Edition 4.7 in the form of runnable .jar. file - corda-tools-blob-inspector-4.7.jar.

To run simply pass in the file or URL as the first parameter:

java -jar corda-tools-blob-inspector-4.7.jar <file or URL>

Use the --help flag for a full list of command line options.

When inspecting your custom data structures, there is no need to include the jars containing the class definitions for them in the classpath. The blob inspector (or rather the serialization framework) is able to synthesis any classes found in the blob that are not on the classpath.

Supported formats

The inspector can read input data in three formats: raw binary, hex encoded text and base64 encoded text. For instance if you have retrieved your binary data and it looks like this:

636f7264610100000080c562000000000001d0000030720000000300a3226e65742e636f7264613a38674f537471464b414a5055...

then you have hex encoded data. If it looks like this it’s base64 encoded:

Y29yZGEBAAAAgMViAAAAAAAB0AAAMHIAAAADAKMibmV0LmNvcmRhOjhnT1N0cUZLQUpQVWVvY2Z2M1NlU1E9PdAAACc1AAAAAgCjIm5l...

And if it looks like something vomited over your screen it’s raw binary. You don’t normally need to care about these differences because the tool will try every format until it works.

Something that’s useful to know about Corda’s format is that it always starts with the word “corda” in binary. Try hex decoding 636f726461 using the online hex decoder tool here to see for yourself.

Output data can be in either a slightly extended form of YaML or JSON. YaML (Yet another markup language) is a bit easier to read for humans and is the default. JSON can of course be parsed by any JSON library in any language.

Example

Here’s what a node-info file from the node’s data directory may look like:

• YAML:

net.corda.nodeapi.internal.SignedNodeInfo
---
raw:
  class: "net.corda.core.node.NodeInfo"
  deserialized:
    addresses:
    - "localhost:10005"
    legalIdentitiesAndCerts:
    - "O=BankOfCorda, L=London, C=GB"
    platformVersion: 4
    serial: 1527851068715
signatures:
- !!binary |-
  VFRy4frbgRDbCpK1Vo88PyUoj01vbRnMR3ROR2abTFk7yJ14901aeScX/CiEP+CDGiMRsdw01cXt\nhKSobAY7Dw==

• JSON:

net.corda.nodeapi.internal.SignedNodeInfo
{
  "raw" : {
    "class" : "net.corda.core.node.NodeInfo",
    "deserialized" : {
      "addresses" : [ "localhost:10005" ],
      "legalIdentitiesAndCerts" : [ "O=BankOfCorda, L=London, C=GB" ],
      "platformVersion" : 4,
      "serial" : 1527851068715
    }
  },
  "signatures" : [ "VFRy4frbgRDbCpK1Vo88PyUoj01vbRnMR3ROR2abTFk7yJ14901aeScX/CiEP+CDGiMRsdw01cXthKSobAY7Dw==" ]
}

Notice the file is actually a serialized SignedNodeInfo object, which has a raw property of type SerializedBytes<NodeInfo>. This property is materialised into a NodeInfo and is output under the deserialized field.

Classpath

If you run the blob inspector without any JAR files on the classpath, then it will deserialize objects using the Class Carpenter (see Object serialization for details). The reason for this is that the types are not available, so the serialization framework has to synthesise them.

Command-line options

The blob inspector can be started with the following command-line options:

blob-inspector [-hvV] [--full-parties] [--schema] [--format=type]
               [--input-format=type] [--logging-level=<loggingLevel>] SOURCE
               [COMMAND]

• --format=type: Output format. Possible values: [YAML, JSON]. Default: YAML.
• --input-format=type: Input format. If the file can’t be decoded with the given value it’s auto-detected, so you should never normally need to specify this. Possible values [BINARY, HEX, BASE64]. Default: BINARY.
• --full-parties: Display the owningKey and certPath properties of Party and PartyAndReference objects respectively.
• --schema: Print the blob’s schema first.
• --verbose, --log-to-console, -v: If set, prints logging to the console as well as to a file.
• --logging-level=<loggingLevel>: Enable logging at this level and higher. Possible values: ERROR, WARN, INFO, DEBUG, TRACE. Default: INFO.
• --help, -h: Show this help message and exit.
• --version, -V: Print version information and exit.

Sub-commands

install-shell-extensions: Install blob-inspector alias and auto completion for bash and zsh. See cli-application-shell-extensions for more info.