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| 1 | +# This file is part of NIT ( http://www.nitlanguage.org ). |
| 2 | +# |
| 3 | +# Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | +# you may not use this file except in compliance with the License. |
| 5 | +# You may obtain a copy of the License at |
| 6 | +# |
| 7 | +# http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | +# |
| 9 | +# Unless required by applicable law or agreed to in writing, software |
| 10 | +# distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | +# See the License for the specific language governing permissions and |
| 13 | +# limitations under the License. |
| 14 | + |
| 15 | +# HTTP request services: `AsyncHttpRequest` and `Text::http_get` |
| 16 | +module http_request |
| 17 | + |
| 18 | +import app_base |
| 19 | +import pthreads |
| 20 | +import json::serialization |
| 21 | + |
| 22 | +import linux::http_request is conditional(linux) |
| 23 | +import android::http_request is conditional(android) |
| 24 | + |
| 25 | +redef class App |
| 26 | + # Platform specific service to execute `task` on the main/UI thread |
| 27 | + fun run_on_ui_thread(task: Task) is abstract |
| 28 | +end |
| 29 | + |
| 30 | +# Thread executing an HTTP request and deserializing JSON asynchronously |
| 31 | +# |
| 32 | +# This class defines four methods acting on the main/UI thread, |
| 33 | +# they should be implemented as needed: |
| 34 | +# * before |
| 35 | +# * on_load |
| 36 | +# * on_fail |
| 37 | +# * after |
| 38 | +class AsyncHttpRequest |
| 39 | + super Thread |
| 40 | + |
| 41 | + # Root URI of the remote server |
| 42 | + fun rest_server_uri: String is abstract |
| 43 | + |
| 44 | + # Action, or path, for this request within the `rest_server_uri` |
| 45 | + fun rest_action: String is abstract |
| 46 | + |
| 47 | + # Should the response content be deserialized from JSON? |
| 48 | + var deserialize_json = true is writable |
| 49 | + |
| 50 | + redef fun start |
| 51 | + do |
| 52 | + before |
| 53 | + super |
| 54 | + end |
| 55 | + |
| 56 | + redef fun main |
| 57 | + do |
| 58 | + var uri = rest_server_uri / rest_action |
| 59 | + |
| 60 | + # Execute REST request |
| 61 | + var rep = uri.http_get |
| 62 | + if rep.is_error then |
| 63 | + app.run_on_ui_thread new RestRunnableOnFail(self, rep.error) |
| 64 | + return null |
| 65 | + end |
| 66 | + |
| 67 | + if not deserialize_json then |
| 68 | + app.run_on_ui_thread new RestRunnableOnLoad(self, rep) |
| 69 | + return null |
| 70 | + end |
| 71 | + |
| 72 | + # Deserialize |
| 73 | + var deserializer = new JsonDeserializer(rep.value) |
| 74 | + var res = deserializer.deserialize |
| 75 | + if deserializer.errors.not_empty then |
| 76 | + app.run_on_ui_thread new RestRunnableOnFail(self, deserializer.errors.first) |
| 77 | + end |
| 78 | + |
| 79 | + app.run_on_ui_thread new RestRunnableOnLoad(self, res) |
| 80 | + return null |
| 81 | + end |
| 82 | + |
| 83 | + # Prepare the UI or other parts of the program before executing the REST request |
| 84 | + fun before do end |
| 85 | + |
| 86 | + # Invoked when the HTTP request returned valid data |
| 87 | + # |
| 88 | + # If `deserialize_json`, the default behavior, this method is invoked only if deserialization was successful. |
| 89 | + # In this case, `result` may be any deserialized object. |
| 90 | + # |
| 91 | + # Otherwise, if `not deserialize_json`, `result` contains the content of the response as a `String`. |
| 92 | + fun on_load(result: nullable Object) do end |
| 93 | + |
| 94 | + # Invoked when the HTTP request has failed and no data was received or deserialization failed |
| 95 | + fun on_fail(error: Error) do print_error "REST request '{rest_action}' failed with: {error}" |
| 96 | + |
| 97 | + # Complete this request whether it was a success or not |
| 98 | + fun after do end |
| 99 | +end |
| 100 | + |
| 101 | +redef class Text |
| 102 | + # Execute an HTTP GET request synchronously at the URI `self` |
| 103 | + # |
| 104 | + # ~~~nitish |
| 105 | + # var response = "http://example.org/".http_get |
| 106 | + # if response.is_error then |
| 107 | + # print_error response.error |
| 108 | + # else |
| 109 | + # print "HTTP status code: {response.code}" |
| 110 | + # print response.value |
| 111 | + # end |
| 112 | + # ~~~ |
| 113 | + private fun http_get: HttpRequestResult is abstract |
| 114 | +end |
| 115 | + |
| 116 | +# Result of a call to `Text::http_get` |
| 117 | +# |
| 118 | +# Users should first check if `is_error` to use `error`. |
| 119 | +# Otherwise they can use `value` to get the content of the response |
| 120 | +# and `code` for the HTTP status code. |
| 121 | +class HttpRequestResult |
| 122 | + super MaybeError[String, Error] |
| 123 | + |
| 124 | + # The HTTP status code, if any |
| 125 | + var maybe_code: nullable Int |
| 126 | + |
| 127 | + # The status code |
| 128 | + # Require: `not is_error` |
| 129 | + fun code: Int do return maybe_code.as(not null) |
| 130 | +end |
| 131 | + |
| 132 | +private abstract class HttpRequestTask |
| 133 | + super Task |
| 134 | + |
| 135 | + # `AsyncHttpRequest` to which send callbacks |
| 136 | + var sender_thread: AsyncHttpRequest |
| 137 | +end |
| 138 | + |
| 139 | +private class RestRunnableOnLoad |
| 140 | + super HttpRequestTask |
| 141 | + |
| 142 | + var res: nullable Object |
| 143 | + |
| 144 | + redef fun main |
| 145 | + do |
| 146 | + sender_thread.on_load(res) |
| 147 | + sender_thread.after |
| 148 | + end |
| 149 | +end |
| 150 | + |
| 151 | +private class RestRunnableOnFail |
| 152 | + super HttpRequestTask |
| 153 | + |
| 154 | + var error: Error |
| 155 | + |
| 156 | + redef fun main |
| 157 | + do |
| 158 | + sender_thread.on_fail(error) |
| 159 | + sender_thread.after |
| 160 | + end |
| 161 | +end |
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