将聊天服务器应用程序从 parse.com 移至 Google 应用引擎
Posted
技术标签:
【中文标题】将聊天服务器应用程序从 parse.com 移至 Google 应用引擎【英文标题】：Moving a chat server application from parse.com to google app engine 【发布时间】：2016-05-25 09:38:18 【问题描述】：我们计划将驻留在 parse.com 上的聊天服务器应用程序移动到 Google 应用引擎的数据存储区，因为 parse 将于 2017 年 1 月关闭它的服务。我认为这应该可以通过 App engine's XMPP API 实现。不确定，我很高兴收到您的来信..
目前我正在使用Google提供的这段代码进行测试
# Copyright 2009 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Crowdguru sample application using the XMPP service on Google App Engine."""
import datetime
from google.appengine.api import datastore_types
from google.appengine.api import xmpp
from google.appengine.ext import ndb
from google.appengine.ext.webapp import xmpp_handlers
import webapp2
from webapp2_extras import jinja2
PONDER_MSG = 'Hmm. Let me think on that a bit.'
TELLME_MSG = 'While I\'m thinking, perhaps you can answer me this: '
SOMEONE_ANSWERED_MSG = ('We seek those who are wise and fast. One out of two '
'is not enough. Another has answered my question.')
ANSWER_INTRO_MSG = 'You asked me: '
ANSWER_MSG = 'I have thought long and hard, and concluded: '
WAIT_MSG = ('Please! One question at a time! You can ask me another once you '
'have an answer to your current question.')
THANKS_MSG = 'Thank you for your wisdom.'
TELLME_THANKS_MSG = THANKS_MSG + ' I\'m still thinking about your question.'
EMPTYQ_MSG = 'Sorry, I don\'t have anything to ask you at the moment.'
HELP_MSG = ('I am the amazing Crowd Guru. Ask me a question by typing '
'\'/tellme the meaning of life\', and I will answer you forthwith! '
'To learn more, go to /')
MAX_ANSWER_TIME = 120
class IMProperty(ndb.StringProperty):
"""A custom property for handling IM objects.
IM or Instant Message objects include both an address and its protocol. The
constructor and __str__ method on these objects allow easy translation from
type string to type datastore_types.IM.
"""
def _validate(self, value):
"""Validator to make sure value is an instance of datastore_types.IM.
Args:
value: The value to be validated. Should be an instance of
datastore_types.IM.
Raises:
TypeError: If value is not an instance of datastore_types.IM.
"""
if not isinstance(value, datastore_types.IM):
raise TypeError('expected an IM, got !r'.format(value))
def _to_base_type(self, value):
"""Converts native type (datastore_types.IM) to datastore type (string).
Args:
value: The value to be converted. Should be an instance of
datastore_types.IM.
Returns:
String corresponding to the IM value.
"""
return str(value)
def _from_base_type(self, value):
"""Converts datastore type (string) to native type (datastore_types.IM).
Args:
value: The value to be converted. Should be a string.
Returns:
String corresponding to the IM value.
"""
return datastore_types.IM(value)
class Question(ndb.Model):
"""Model to hold questions that the Guru can answer."""
question = ndb.TextProperty(required=True)
asker = IMProperty(required=True)
asked = ndb.DateTimeProperty(required=True, auto_now_add=True)
suspended = ndb.BooleanProperty(required=True)
assignees = IMProperty(repeated=True)
last_assigned = ndb.DateTimeProperty()
answer = ndb.TextProperty(indexed=True)
answerer = IMProperty()
answered = ndb.DateTimeProperty()
@staticmethod
@ndb.transactional
def _try_assign(key, user, expiry):
"""Assigns and returns the question if it's not assigned already.
Args:
key: ndb.Key: The key of a Question to try and assign.
user: datastore_types.IM: The user to assign the question to.
expiry: datetime.datetime: The expiry date of the question.
Returns:
The Question object. If it was already assigned, no change is made.
"""
question = key.get()
if not question.last_assigned or question.last_assigned < expiry:
question.assignees.append(user)
question.last_assigned = datetime.datetime.now()
question.put()
return question
@classmethod
def assign_question(cls, user):
"""Gets an unanswered question and assigns it to a user to answer.
Args:
user: datastore_types.IM: The identity of the user to assign a
question to.
Returns:
The Question entity assigned to the user, or None if there are no
unanswered questions.
"""
question = None
while question is None or user not in question.assignees:
# Assignments made before this timestamp have expired.
expiry = (datetime.datetime.now()
- datetime.timedelta(seconds=MAX_ANSWER_TIME))
# Find a candidate question
query = cls.query(cls.answerer == None, cls.last_assigned < expiry)
# If a question has never been assigned, order by when it was asked
query = query.order(cls.last_assigned, cls.asked)
candidates = [candidate for candidate in query.fetch(2)
if candidate.asker != user]
if not candidates:
# No valid questions in queue.
break
# Try and assign it
question = cls._try_assign(candidates[0].key, user, expiry)
# Expire the assignment after a couple of minutes
return question
@ndb.transactional
def unassign(self, user):
"""Unassigns the given user from this question.
Args:
user: datastore_types.IM: The user who will no longer be answering
this question.
"""
question = self.key.get()
if user in question.assignees:
question.assignees.remove(user)
question.put()
@classmethod
def get_asked(cls, user):
"""Returns the user's outstanding asked question, if any.
Args:
user: datastore_types.IM: The identity of the user asking.
Returns:
An unanswered Question entity asked by the user, or None if there
are no unanswered questions.
"""
query = cls.query(cls.asker == user, cls.answer == None)
return query.get()
@classmethod
def get_answering(cls, user):
"""Returns the question the user is answering, if any.
Args:
user: datastore_types.IM: The identity of the user answering.
Returns:
An unanswered Question entity assigned to the user, or None if there
are no unanswered questions.
"""
query = cls.query(cls.assignees == user, cls.answer == None)
return query.get()
def bare_jid(sender):
"""Identify the user by bare jid.
See http://wiki.xmpp.org/web/Jabber_Resources for more details.
Args:
sender: String; A jabber or XMPP sender.
Returns:
The bare Jabber ID of the sender.
"""
return sender.split('/')[0]
class XmppHandler(xmpp_handlers.CommandHandler):
"""Handler class for all XMPP activity."""
def unhandled_command(self, message=None):
"""Shows help text for commands which have no handler.
Args:
message: xmpp.Message: The message that was sent by the user.
"""
message.reply(HELP_MSG.format(self.request.host_url))
def askme_command(self, message=None):
"""Responds to the /askme command.
Args:
message: xmpp.Message: The message that was sent by the user.
"""
im_from = datastore_types.IM('xmpp', bare_jid(message.sender))
currently_answering = Question.get_answering(im_from)
question = Question.assign_question(im_from)
if question:
message.reply(TELLME_MSG.format(question.question))
else:
message.reply(EMPTYQ_MSG)
# Don't unassign their current question until we've picked a new one.
if currently_answering:
currently_answering.unassign(im_from)
def text_message(self, message=None):
"""Called when a message not prefixed by a /cmd is sent to the XMPP bot.
Args:
message: xmpp.Message: The message that was sent by the user.
"""
im_from = datastore_types.IM('xmpp', bare_jid(message.sender))
question = Question.get_answering(im_from)
if question:
other_assignees = question.assignees
other_assignees.remove(im_from)
# Answering a question
question.answer = message.arg
question.answerer = im_from
question.assignees = []
question.answered = datetime.datetime.now()
question.put()
# Send the answer to the asker
xmpp.send_message([question.asker.address],
ANSWER_INTRO_MSG.format(question.question))
xmpp.send_message([question.asker.address],
ANSWER_MSG.format(message.arg))
# Send acknowledgement to the answerer
asked_question = Question.get_asked(im_from)
if asked_question:
message.reply(TELLME_THANKS_MSG)
else:
message.reply(THANKS_MSG)
# Tell any other assignees their help is no longer required
if other_assignees:
xmpp.send_message([user.address for user in other_assignees],
SOMEONE_ANSWERED_MSG)
else:
self.unhandled_command(message)
def tellme_command(self, message=None):
"""Handles /tellme requests, asking the Guru a question.
Args:
message: xmpp.Message: The message that was sent by the user.
"""
im_from = datastore_types.IM('xmpp', bare_jid(message.sender))
asked_question = Question.get_asked(im_from)
if asked_question:
# Already have a question
message.reply(WAIT_MSG)
else:
# Asking a question
asked_question = Question(question=message.arg, asker=im_from)
asked_question.put()
currently_answering = Question.get_answering(im_from)
if not currently_answering:
# Try and find one for them to answer
question = Question.assign_question(im_from)
if question:
message.reply(TELLME_MSG.format(question.question))
return
message.reply(PONDER_MSG)
class XmppPresenceHandler(webapp2.RequestHandler):
"""Handler class for XMPP status updates."""
def post(self, status):
"""POST handler for XMPP presence.
Args:
status: A string which will be either available or unavailable
and will indicate the status of the user.
"""
sender = self.request.get('from')
im_from = datastore_types.IM('xmpp', bare_jid(sender))
suspend = (status == 'unavailable')
query = Question.query(Question.asker == im_from,
Question.answer == None,
Question.suspended == (not suspend))
question = query.get()
if question:
question.suspended = suspend
question.put()
class LatestHandler(webapp2.RequestHandler):
"""Displays the most recently answered questions."""
@webapp2.cached_property
def jinja2(self):
"""Cached property holding a Jinja2 instance.
Returns:
A Jinja2 object for the current app.
"""
return jinja2.get_jinja2(app=self.app)
def render_response(self, template, **context):
"""Use Jinja2 instance to render template and write to output.
Args:
template: filename (relative to $PROJECT/templates) that we are
rendering.
context: keyword arguments corresponding to variables in template.
"""
rendered_value = self.jinja2.render_template(template, **context)
self.response.write(rendered_value)
def get(self):
"""Handler for latest questions page."""
query = Question.query(Question.answered > None).order(
-Question.answered)
self.render_response('latest.html', questions=query.fetch(20))
APPLICATION = webapp2.WSGIApplication([
('/', LatestHandler),
('/_ah/xmpp/message/chat/', XmppHandler),
('/_ah/xmpp/presence/(available|unavailable)/', XmppPresenceHandler),
], debug=True)
如果用户选择了另一个他想与之聊天的用户，则应调用 API url /_ah/xmpp/message/chat/，它会自动调用 XmppHandler 处理程序。
('/_ah/xmpp/message/chat/', XmppHandler)
我的疑问是，如果他在该特定聊天中发布类似 foo 的消息，它是否会自动调用 text_message 中存在的 XmppHandler 方法？我们是否还需要在客户端配置 xmpp？
【问题讨论】：
对 s.o 来说似乎太宽泛了。到目前为止您尝试过什么？什么失败了？你怀疑什么问题？ xmpp 似乎只是您迁移的一小部分。 @ZigMandel 已更新... 伙计们，我不是在问迁移..我只是想用客户端代码测试上面的服务器代码..请提供一些android客户端代码..不知道是否通过服务器发送和接收消息是否应该立即工作.. 问题太宽泛了。 xmpp 与您需要的所有内容相比，这是一个小问题。一个答案已经发布了将解析移至 appengine 的详细指南。 @Zig Mandel 忘记了解析迁移。我需要创建一个应该与 gae 一起使用的 android 聊天应用程序。如果我从该应用发出发布请求，上述代码是否有效？ 【参考方案1】：对于客户端 api 兼容和数据库迁移，您可以托管自己的解析服务器。
有一个使用 parse-server 的简单 express 项目。 https://github.com/ParsePlatform/parse-server-example
它们是每个云平台的大量部署指南
Google App Engine
Heroku and mLab
AWS and Elastic Beanstalk
Digital Ocean
NodeChef
Microsoft Azure
Pivotal Web Services
Back4app
或者您可以使用您的域名托管您的 nodejs 服务器。
如果你想做一些与解析不同的事情，你可以向parse-server 发送拉取请求。 LiveQuery 是贡献者创建的额外功能。
有关详细信息，请参阅来自Parse.com、github wiki 和community links 的链接。
【讨论】：
你对***.com/questions/37653184/…有什么想法吗？ 对不起，我没有 GAE、python、xmpp 的经验。【参考方案2】：Parse 提供了有关迁移的detailed information 过程以及如何将我们的应用程序从他们的服务器移动到单独的 托管 mongoDB 实例和云公司。 Parse 建议 迁移分两步进行：
数据库已迁移到 MongoLab 或 ObjectRocket 等服务。 将服务器迁移到 AWS、Google App Engine 或 Heroku 等云托管公司。
Parse 还设置了建议的截止日期：
他们建议在 2016 年 4 月 28 日之前迁移数据库，并在 2016年7月28日，服务器迁移正常。
这将为您提供充足的时间来解决任何错误并确保您的应用正常运行而不会停机！
Backend-as-a-Service 像 parse.com 将所谓的后端的两个方面结合为一个：server 和 database。操作数据库、执行查询、获取信息和其他工作密集型任务的服务器与数据库交互。两者携手合作，形成一个后端。
随着 Parse 的消失，我们必须处理服务器和数据库 分开。
Parse 已经为托管在任何云上的 Mongodb 提供了数据库detailed info and easy migration tool。
此外，在任何云平台（包括 Google App Engine）上设置基于节点的解析服务器都很容易：
让 Parse 服务器在 Google Cloud 上运行的最简单方法是从 sample out on GitHub 开始。
【讨论】：
以上是关于将聊天服务器应用程序从 parse.com 移至 Google 应用引擎的主要内容，如果未能解决你的问题，请参考以下文章
Android - 使用我自己的数据使用 parse.com 制作聊天应用程序
Parse.com - 从 Parse.com 向 iOS 应用程序发送消息，不像推送通知
android 使用 parse.com api 通过推送通知实现聊天