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Parser Plugin example for jMISB

This is demonstration / example code for https://github.com/WestRidgeSystems/jmisb

It shows how to add a parser to jMISB without modifying the source code. This might be useful where you need to support a custom (not MISB standardised) local set or universal set.

In this example (based on a production system), there is a message that is not parsed correctly by jMISB, and is to returned as a RawMisbMessage.

The structure looks like:

0x06, 0x0e, 0x2b, 0x34, 0x01, 0x01, 0x01, 0x03, 0x07, 0x02, 0x01, 0x01, 0x01, 0x05, 0x00, 0x00,
0x08, 0x00, 0x05, 0x09, 0x95, 0xc4, 0xff, 0xba, 0x00

For the sake of this example, this is the "Time Message" structure.

The first 16 bytes are a Universal Label. Typically you'd have documentation defining your message, but in this case, it happens to match the Precision Time Stamp field registered in SMPTE RP210. The next byte (0x08) is the length - it is BER-OID encoded, but for this example is effectively a constant. The remaining 8 bytes are the timestamp value.

There is more on this in TRM1006, which just happens to use the same structure for one of its examples.

Writing a parser for this is relatively easy. One approach would be to skip over the Universal Label and length, and then parse the timestamp. Because a timestamp is such a common thing in motion imagery, we can just use the code in ST0603 for the timestamp itself. A more complex example might use the LdsParser utility code to parse a local set, or the UdsParser to parse a universal set. More advanced parsing is of course possible. If you are looking for a simple local set example, try ST0808.

So we can parse the message, and return our own IMisbMessage implementation instead of getting a RawMisbMessage. That implementation is TimeMessage in the example code. The supporting code is more complex than strictly needed, but is intended provide a model for more complex structures.

To link in our parser, we use a simple factory (TimeMessageFactory in the example). That gets registered with code that looks like:

        TimeMessageFactory timeMessageFactory = new TimeMessageFactory();
        MisbMessageFactory.getInstance()
                .registerHandler(TimeMessageConstants.TIME_STAMP_UL, timeMessageFactory);

The constant TIME_STAMP_UL is just the UniversalLabel that matches what we want to handle.

When its all wired up, the output of the metadata dump will look like:

Time Message Example
        Precision Time Stamp: 2014-12-07T00:55:43.424

Note that this plugin is not restricted to command line parsing. It will work wherever its loaded.

Building

To build the example, use maven.

mvn clean install

Using

There are several ways to invoke it. One way is:

java -jar target/parserplugin-1.10.1-jar-with-dependencies.jar {filename}

Helping us

Please provide pull requests.