dremio 的webserver 是基于jetty+jersey 开发的web server 同时也和标准的dremio 服务一样实现了service 接口方便服务的启动
具体是由DACDaemon 调用触发的启动
webserver start 服务
@Override
public void start() throws Exception {
// 使用了DremioServer 服务进行实际的启动
server.startDremioServer(
registry,
config,
credentialsServiceProvider,
uiType,
this::registerEndpoints
);
}
jetty+jersey 服务的启动
DremioServer 类中
public void startDremioServer(
SingletonRegistry registry,
DACConfig config,
Provider<CredentialsService> credentialsServiceProvider,
String uiType,
Consumer<ServletContextHandler> servletRegistrer
) throws Exception {
this.credentialsServiceProvider = credentialsServiceProvider;
try {
if (!embeddedJetty.isRunning()) {
// 创建jetty 的connector
createConnector(config);
// 添加handlers，包含了不少dremio 内部的服务
addHandlers();
}
if (config.verboseAccessLog) {
accessLogFilter = new AccessLogFilter();
// 此处servletContextHandler 是在addHandlers 中初始化的
servletContextHandler.addFilter(
new FilterHolder(accessLogFilter),
"/*",
EnumSet.of(DispatcherType.REQUEST));
}
if (config.serveUI) {
final String basePath = "rest/dremio_static/";
final String markerPath = String.format("META-INF/%s.properties", uiType);
// dremio 自己的一个servlet
final ServletHolder fallbackServletHolder = new ServletHolder("fallback-servlet", registry.lookup(DremioServlet.class));
addStaticPath(fallbackServletHolder, basePath, markerPath);
servletContextHandler.addServlet(fallbackServletHolder, "/*");
}
if (servletRegistrer != null) {
servletRegistrer.accept(servletContextHandler);
}
if (!embeddedJetty.isRunning()) {
embeddedJetty.start();
}
setPortFromConnector();
logger.info("Started on {}://localhost:" + port, config.webSSLEnabled() ? "https" : "http");
serviceStarted = true;
} catch (Exception ex) {
throw new ServerErrorException(ex);
}
}
其他api endpoint 的注册
WebServer 类中，基于了DremioServer 提供的一个函数接口，注册了不少dremio 的api 接口
使用了jetty 提供的ServletHolder 动态的servlet 注册接口，同时利用了ResourceConfig
protected void registerEndpoints(ServletContextHandler servletContextHandler) {
// security header filters
SecurityHeadersFilter securityHeadersFilter = new SecurityHeadersFilter(registry.provider(OptionManager.class));
servletContextHandler.addFilter(new FilterHolder(securityHeadersFilter), "/*", EnumSet.of(DispatcherType.REQUEST));
// Generic Response Headers filter for api responses
servletContextHandler.addFilter(GenericResponseHeadersFilter.class.getName(), "/apiv2/*", EnumSet.of(DispatcherType.REQUEST));
servletContextHandler.addFilter(GenericResponseHeadersFilter.class.getName(), "/api/*", EnumSet.of(DispatcherType.REQUEST));
// add the font mime type.
final MimeTypes mimeTypes = servletContextHandler.getMimeTypes();
mimeTypes.addMimeMapping("woff2", "application/font-woff2; charset=utf-8");
servletContextHandler.setMimeTypes(mimeTypes);
// WebSocket API
final SocketServlet servlet = new SocketServlet(registry.lookup(JobsService.class), registry.lookup(TokenManager.class),
registry.provider(OptionManager.class));
final ServletHolder wsHolder = new ServletHolder(servlet);
wsHolder.setInitOrder(1);
servletContextHandler.addServlet(wsHolder, "/apiv2/socket");
// Rest API
ResourceConfig restServer = restServerProvider.get();
restServer.property(RestServerV2.ERROR_STACKTRACE_ENABLE, config.sendStackTraceToClient);
restServer.property(RestServerV2.TEST_API_ENABLE, config.allowTestApis);
restServer.property(RestServerV2.FIRST_TIME_API_ENABLE, isInternalUS);
restServer.register(dremioBinder);
restServer.register((DynamicFeature) (resourceInfo, context) -> context.register(DremioServer.TracingFilter.class));
final ServletHolder restHolder = new ServletHolder(new ServletContainer(restServer));
restHolder.setInitOrder(2);
servletContextHandler.addServlet(restHolder, "/apiv2/*");
// Public API
ResourceConfig apiServer = apiServerProvider.get();
apiServer.register(dremioBinder);
apiServer.register((DynamicFeature) (resourceInfo, context) -> context.register(DremioServer.TracingFilter.class));
final ServletHolder apiHolder = new ServletHolder(new ServletContainer(apiServer));
apiHolder.setInitOrder(3);
servletContextHandler.addServlet(apiHolder, "/api/v3/*");
}
dremio 自己的实现
包含了APIServer以及RestServerV2
- 参考类图
基于了ResourceConfig 进行了动态扩展 
有一个灵活的设计是，dremio 基于了注解实现动态注册，比如api 以及rest 都包含了自己的注解扩展
protected void init(ScanResult result) {
// FILTERS
register(JSONPrettyPrintFilter.class);
register(MediaTypeFilter.class);
// RESOURCES
// 基于APIResource 注解，通过调用register 动态注册接口服务
for (Class<?> resource : result.getAnnotatedClasses(APIResource.class)) {
register(resource);
}
// FEATURES
register(DACAuthFilterFeature.class);
register(DACJacksonJaxbJsonFeature.class);
register(DACExceptionMapperFeature.class);
// EXCEPTION MAPPERS
register(JsonParseExceptionMapper.class);
register(JsonMappingExceptionMapper.class);
// PROPERTIES
property(ServerProperties.RESPONSE_SET_STATUS_OVER_SEND_ERROR, "true");
property(RestServerV2.TEST_API_ENABLE, "true");
final String disableMoxy = PropertiesHelper.getPropertyNameForRuntime(CommonProperties.MOXY_JSON_FEATURE_DISABLE,
getConfiguration().getRuntimeType());
property(disableMoxy, true);
}
说明
以上是一个简单的dremio webserver 服务介绍，基于此可以了解dremio api的运行机制，可以更好的进行扩展，实际上dremio 的api 部分还包含了
认证、日志以及一些其他服务，可以通过阅读源码查看学习
参考资料
dac/backend/src/main/java/com/dremio/dac/server/WebServer.java
dac/backend/src/main/java/com/dremio/dac/server/DremioServer.java
dac/backend/src/main/java/com/dremio/dac/server/DremioServlet.java
dac/backend/src/main/java/com/dremio/dac/daemon/DACDaemonModule.java