1 /* 2 Package restful , a lean package for creating REST-style WebServices without magic. 3 4 WebServices and Routes 5 6 A WebService has a collection of Route objects that dispatch incoming Http Requests to a function calls. 7 Typically, a WebService has a root path (e.g. /users) and defines common MIME types for its routes. 8 WebServices must be added to a container (see below) in order to handler Http requests from a server. 9 10 A Route is defined by a HTTP method, an URL path and (optionally) the MIME types it consumes (Content-Type) and produces (Accept). 11 This package has the logic to find the best matching Route and if found, call its Function. 12 13 ws := new(restful.WebService) 14 ws. 15 Path("/users"). 16 Consumes(restful.MIME_JSON, restful.MIME_XML). 17 Produces(restful.MIME_JSON, restful.MIME_XML) 18 19 ws.Route(ws.GET("/{user-id}").To(u.findUser)) // u is a UserResource 20 21 ... 22 23 // GET http://localhost:8080/users/1 24 func (u UserResource) findUser(request *restful.Request, response *restful.Response) { 25 id := request.PathParameter("user-id") 26 ... 27 } 28 29 The (*Request, *Response) arguments provide functions for reading information from the request and writing information back to the response. 30 31 See the example https://github.com/emicklei/go-restful/blob/v3/examples/user-resource/restful-user-resource.go with a full implementation. 32 33 Regular expression matching Routes 34 35 A Route parameter can be specified using the format "uri/{var[:regexp]}" or the special version "uri/{var:*}" for matching the tail of the path. 36 For example, /persons/{name:[A-Z][A-Z]} can be used to restrict values for the parameter "name" to only contain capital alphabetic characters. 37 Regular expressions must use the standard Go syntax as described in the regexp package. (https://code.google.com/p/re2/wiki/Syntax) 38 This feature requires the use of a CurlyRouter. 39 40 Containers 41 42 A Container holds a collection of WebServices, Filters and a http.ServeMux for multiplexing http requests. 43 Using the statements "restful.Add(...) and restful.Filter(...)" will register WebServices and Filters to the Default Container. 44 The Default container of go-restful uses the http.DefaultServeMux. 45 You can create your own Container and create a new http.Server for that particular container. 46 47 container := restful.NewContainer() 48 server := &http.Server{Addr: ":8081", Handler: container} 49 50 Filters 51 52 A filter dynamically intercepts requests and responses to transform or use the information contained in the requests or responses. 53 You can use filters to perform generic logging, measurement, authentication, redirect, set response headers etc. 54 In the restful package there are three hooks into the request,response flow where filters can be added. 55 Each filter must define a FilterFunction: 56 57 func (req *restful.Request, resp *restful.Response, chain *restful.FilterChain) 58 59 Use the following statement to pass the request,response pair to the next filter or RouteFunction 60 61 chain.ProcessFilter(req, resp) 62 63 Container Filters 64 65 These are processed before any registered WebService. 66 67 // install a (global) filter for the default container (processed before any webservice) 68 restful.Filter(globalLogging) 69 70 WebService Filters 71 72 These are processed before any Route of a WebService. 73 74 // install a webservice filter (processed before any route) 75 ws.Filter(webserviceLogging).Filter(measureTime) 76 77 78 Route Filters 79 80 These are processed before calling the function associated with the Route. 81 82 // install 2 chained route filters (processed before calling findUser) 83 ws.Route(ws.GET("/{user-id}").Filter(routeLogging).Filter(NewCountFilter().routeCounter).To(findUser)) 84 85 See the example https://github.com/emicklei/go-restful/blob/v3/examples/filters/restful-filters.go with full implementations. 86 87 Response Encoding 88 89 Two encodings are supported: gzip and deflate. To enable this for all responses: 90 91 restful.DefaultContainer.EnableContentEncoding(true) 92 93 If a Http request includes the Accept-Encoding header then the response content will be compressed using the specified encoding. 94 Alternatively, you can create a Filter that performs the encoding and install it per WebService or Route. 95 96 See the example https://github.com/emicklei/go-restful/blob/v3/examples/encoding/restful-encoding-filter.go 97 98 OPTIONS support 99 100 By installing a pre-defined container filter, your Webservice(s) can respond to the OPTIONS Http request. 101 102 Filter(OPTIONSFilter()) 103 104 CORS 105 106 By installing the filter of a CrossOriginResourceSharing (CORS), your WebService(s) can handle CORS requests. 107 108 cors := CrossOriginResourceSharing{ExposeHeaders: []string{"X-My-Header"}, CookiesAllowed: false, Container: DefaultContainer} 109 Filter(cors.Filter) 110 111 Error Handling 112 113 Unexpected things happen. If a request cannot be processed because of a failure, your service needs to tell via the response what happened and why. 114 For this reason HTTP status codes exist and it is important to use the correct code in every exceptional situation. 115 116 400: Bad Request 117 118 If path or query parameters are not valid (content or type) then use http.StatusBadRequest. 119 120 404: Not Found 121 122 Despite a valid URI, the resource requested may not be available 123 124 500: Internal Server Error 125 126 If the application logic could not process the request (or write the response) then use http.StatusInternalServerError. 127 128 405: Method Not Allowed 129 130 The request has a valid URL but the method (GET,PUT,POST,...) is not allowed. 131 132 406: Not Acceptable 133 134 The request does not have or has an unknown Accept Header set for this operation. 135 136 415: Unsupported Media Type 137 138 The request does not have or has an unknown Content-Type Header set for this operation. 139 140 ServiceError 141 142 In addition to setting the correct (error) Http status code, you can choose to write a ServiceError message on the response. 143 144 Performance options 145 146 This package has several options that affect the performance of your service. It is important to understand them and how you can change it. 147 148 restful.DefaultContainer.DoNotRecover(false) 149 150 DoNotRecover controls whether panics will be caught to return HTTP 500. 151 If set to false, the container will recover from panics. 152 Default value is true 153 154 restful.SetCompressorProvider(NewBoundedCachedCompressors(20, 20)) 155 156 If content encoding is enabled then the default strategy for getting new gzip/zlib writers and readers is to use a sync.Pool. 157 Because writers are expensive structures, performance is even more improved when using a preloaded cache. You can also inject your own implementation. 158 159 Trouble shooting 160 161 This package has the means to produce detail logging of the complete Http request matching process and filter invocation. 162 Enabling this feature requires you to set an implementation of restful.StdLogger (e.g. log.Logger) instance such as: 163 164 restful.TraceLogger(log.New(os.Stdout, "[restful] ", log.LstdFlags|log.Lshortfile)) 165 166 Logging 167 168 The restful.SetLogger() method allows you to override the logger used by the package. By default restful 169 uses the standard library `log` package and logs to stdout. Different logging packages are supported as 170 long as they conform to `StdLogger` interface defined in the `log` sub-package, writing an adapter for your 171 preferred package is simple. 172 173 Resources 174 175 [project]: https://github.com/emicklei/go-restful 176 177 [examples]: https://github.com/emicklei/go-restful/blob/master/examples 178 179 [design]: http://ernestmicklei.com/2012/11/11/go-restful-api-design/ 180 181 [showcases]: https://github.com/emicklei/mora, https://github.com/emicklei/landskape 182 183 (c) 2012-2015, http://ernestmicklei.com. MIT License 184 */ 185 package restful 186