DSL Platform - JSON example

A mini-example illustrating the use of DSL Platform's JSON (de)serialization.
To build and run use the build-and-run-example.sh script (or .bat if on Windows).

Running the build script will perform the following:

• Compile the DSL schema into the src\generated\java folder and package that into target\model.jar
• Compile the main program, and package it into target\dsl-platform-json-example.jar
• Finally, it will run the jar (Main.java program) to show a working example

Best practices for using JsonWriter:

• Reuse JsonWriter whenever possible, remember to reset() before reuse. For per-thread reuse, use something like ThreadLocal<JsonWriter>
• Prefer .toStream(OutputStream) instead of .toByteArray()
• The .toByteArray() is a utility method, which performs an additional copy of the resulting byte array. You can avoid this by using the .toBytes() which gives you access to the result without copying the internal JsonWriter buffer.
• non-nullable collections can be serialized using serialize(array or collection) method.

Best practices for using JsonReader:

• Prefer constructor which reuses the byte[] buffer: JsonReader(byte[], int, ServiceLocator)
• and even char[]: JsonReader(byte[], int, ServiceLocator, char[])

FAQ

Q: What should I provide for ServiceLocator dependency?
A: If you only use JSON part of the library, just provide null for ServiceLocator

Q: How do I register my custom object for JSON?
A: Serialization can be done for any type implementing the com.dslplatform.client.json.JsonObject signature. For deserialization JSON_READER convention should be followed. Each object which needs to be deserialized should have public static com.dslplatform.client.json.JsonReader.ReadJsonObject<Metric> JSON_READER;

Q: How do I register external types (which don't register com.dslplatform.client.json.JsonObject)?
A: com.dslplatform.client.json.DslJsonSerialization contains registerReader and registerWriter methods for custom primitives (this can be used for custom objects too).

Q: Why is DSL JSON faster than others?
A: Almost zero allocations. Works on byte level. Better algorithms for conversion from byte[] -> type and vice-versa. Minimized unexpected branching.