How Alibaba’s TAC Platform Enables Dynamic Java Services and Hot Deployment

2016 Old Version Cat Client Homepage Issues

The 2015 homepage operated by slot management transitioned in 2016 to a fully personalized system with over 50 personalization points, mainly via Aladdin (Tmall recommendation) connecting to TPP (Group personalization platform), while also integrating many third‑party services such as Alibaba Mama ads and newcomer gifts, leading to stability problems.

Problems Identified

Long issue‑localization cycles involving many teams (frontend, backend, Aladdin, algorithm) reduced efficiency.

Personalization support required coordination among the same groups, slowing business response.

Frequent third‑party integrations forced backend releases, degrading homepage stability.

Analysis and Proposed Solution

Backend developers spent excessive effort on service integration, field conversion, and logging, providing low value. The recommendation was to adopt a server‑side dynamic solution that removes low‑value links, allowing frontend developers to directly access business logic and algorithms, thereby shortening issue localization and improving support efficiency.

2017 New Architecture – TAC (Tangram App Container)

TAC is a dynamic service platform designed to support the new 2017 business architecture. Its goals are low‑cost development and publishing, low‑cost environment setup and maintenance, and high stability.

Dynamic Script Language Selection

Given the high‑concurrency, low‑latency mobile environment, Java was chosen for containerization because many developers are already proficient with it, ensuring performance and stability.

Java Dynamic Publishing: Dynamic Compilation, Loading, Hot Deployment

1. Dynamic Compilation Technique

The platform uses the Java Compiler API to compile code strings at runtime.

String nr = "
"; // line break
String source = "package temp.com; " + nr + "public class Hello{" + nr + "public static void main(String[] args){" + nr + "System.out.println(\"HelloWorld! 1\");" + nr + "}" + nr + "}";
File dir = new File(System.getProperty("user.dir") + "/temp");
if (!dir.exists()) { dir.mkdir(); }
FileWriter writer = new FileWriter(new File(dir, "Hello.java"));
writer.write(source);
writer.flush();
writer.close();
JavaCompiler javaCompiler = ToolProvider.getSystemJavaCompiler();
StandardJavaFileManager javaFileManager = javaCompiler.getStandardFileManager(null, null, null);
Iterable<? extends JavaFileObject> it = javaFileManager.getJavaFileObjects(new File(dir, "Hello.java"));
CompilationTask task = javaCompiler.getTask(null, javaFileManager, null, Arrays.asList("-d", "./temp"), null, it);
task.call();
javaFileManager.close();

2. Dynamic Loading Technique

Leveraging Tomcat's class‑loader hierarchy and the parent‑delegation model, multiple classloaders are used to load compiled classes dynamically.

3. Class Hot‑Deployment Technique

Java hot‑deployment is challenging; method‑level hot‑swap (e.g., ASM) cannot replace whole class files.

By redefining the classloader and allowing the old one to be reclaimed by the JVM, full class hot‑deployment is achieved.

TAC Architecture 1.0

TAC consists of a console and an engine.

The console handles dynamic service development, testing, and publishing; class compilation occurs in the pre‑publish stage.

The engine includes a protocol layer (supporting HSF RMI and Hessian), a core responsible for dynamic service loading, execution, security, and monitoring, and a data pool for data services.

TAC Process and Core Technologies

Apply phase (console)

Development phase (console)

Pre‑publish phase – dynamic compilation

Debug phase (console)

Release phase – triggers engine core for dynamic loading and hot‑deployment

Core execution – dynamic loading and hot‑deployment

Online regression (console)

Release result (console)

Supported Services

TAC currently supports over 50 dynamic services, including Tmall wireless business, Cat client homepage selections, brand+, My page, full‑link recommendation, product information consistency, product manuals, etc.

TAC 2.0 Planning

Independent microservice deployment

Microservice inter‑calls

Hybrid cloud deployment

Fully independent engine core

Comprehensive monitoring dashboard

Overall, TAC provides a low‑cost, high‑stability solution for dynamic service development, enabling rapid iteration and robust backend operations.