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# Following XMPP: The Definitive Guide

Slixmpp was featured in the first edition of the O’Reilly book XMPP: The Definitive Guide by Peter Saint-Andre, Kevin Smith, and Remko Tronçon. The original source code for the book’s examples can be found at http://github.com/remko/xmpp-tdg. An updated version of the source code, maintained to stay current with the latest Slixmpp release, is available at http://github.com/legastero/xmpp-tdg.

However, since publication, Slixmpp has advanced from version 0.2.1 to version 1.0 and there have been several major API changes. The most notable is the introduction of stanza objects which have simplified and standardized interactions with the XMPP XML stream.

What follows is a walk-through of The Definitive Guide highlighting the changes needed to make the code examples work with version 1.0 of Slixmpp. These changes have been kept to a minimum to preserve the correlation with the book’s explanations, so be aware that some code may not use current best practices.

## Example 2-2. (Page 26)

Implementation of a basic bot that echoes all incoming messages back to its sender.

The echo bot example requires a change to the `handleIncomingMessage` method to reflect the use of the `Message` stanza object. The `"jid"` field of the message object should now be `"from"` to match the `from` attribute of the actual XML message stanza. Likewise, `"message"` changes to `"body"` to match the `body` element of the message stanza.

### Updated Code

    def handleIncomingMessage(self, message):
        self.xmpp.send_message(message["from"], message["body"])

View full source (1) | View original code (1)

## Example 14-1. (Page 215)

CheshiR IM bot implementation.

The main event handling method in the Bot class is meant to process both message events and presence update events. With the new changes in Slixmpp 1.0, extracting a CheshiR status “message” from both types of stanzas requires accessing different attributes. In the case of a message stanza, the `"body"` attribute would contain the CheshiR message. For a presence event, the information is stored in the `"status"` attribute. To handle both cases, we can test the type of the given event object and look up the proper attribute based on the type.

Like in the EchoBot example, the expression `event["jid"]` needs to change to `event["from"]` in order to get a JID object for the stanza’s sender. Because other functions in CheshiR assume that the JID is a string, the `jid` attribute is used to access the string version of the JID. A check is also added in case `user` is `None`, but the check could (and probably should) be placed in `addMessageFromUser`.

Another change is needed in `handleMessageAddedToBackend` where an HTML-IM response is created. The HTML content should be enclosed in a single element, such as a `<p>` tag.

### Updated Code

    def handleIncomingXMPPEvent(self, event):
      msgLocations = {slixmpp.stanza.presence.Presence: "status",
                      slixmpp.stanza.message.Message: "body"}

      message = event[msgLocations[type(event)]]
      user = self.backend.getUserFromJID(event["from"].jid)
      if user is not None:
        self.backend.addMessageFromUser(message, user)

    def handleMessageAddedToBackend(self, message) :
      body = message.user + ": " + message.text
      htmlBody = "<p><a href='%(uri)s'>%(user)s</a>: %(message)s</p>" % {
        "uri": self.url + "/" + message.user,
        "user" : message.user, "message" : message.text }
      for subscriberJID in self.backend.getSubscriberJIDs(message.user) :
        self.xmpp.send_message(subscriberJID, body, mhtml=htmlBody)

View full source (2) | View original code (2)

## Example 14-3. (Page 217)

Configurable CheshiR IM bot implementation.

Note

Since the CheshiR examples build on each other, see previous sections for corrections to code that is not marked as new in the book example.

The main difference for the configurable IM bot is the handling for the data form in `handleConfigurationCommand`. The test for equality with the string `"1"` is no longer required; Slixmpp converts boolean data form fields to the values `True` and `False` automatically.

For the method `handleIncomingXMPPPresence`, the attribute `"jid"` is again converted to `"from"` to get a JID object for the presence stanza’s sender, and the `jid` attribute is used to access the string version of that JID object. A check is also added in case `user` is `None`, but the check could (and probably should) be placed in `getShouldMonitorPresenceFromUser`.

### Updated Code

    def handleConfigurationCommand(self, form, sessionId):
      values = form.getValues()
      monitorPresence =values["monitorPresence"]
      jid = self.xmpp.plugin["xep_0050"].sessions[sessionId]["jid"]
      user = self.backend.getUserFromJID(jid)
      self.backend.setShouldMonitorPresenceFromUser(user, monitorPresence)

    def handleIncomingXMPPPresence(self, event):
      user = self.backend.getUserFromJID(event["from"].jid)
      if user is not None:
        if self.backend.getShouldMonitorPresenceFromUser(user):
          self.handleIncomingXMPPEvent(event)

View full source (3) | View original code (3)

## Example 14-4. (Page 220)

CheshiR IM server component implementation.

Note

Since the CheshiR examples build on each other, see previous sections for corrections to code that is not marked as new in the book example.

Like several previous examples, a needed change is to replace `subscription["from"]` with `subscription["from"].jid` because the `BaseXMPP` method `make_presence` requires the JID to be a string.

A correction needs to be made in `handleXMPPPresenceProbe` because a line was left out of the original implementation; the variable `user` is undefined. The JID of the user can be extracted from the presence stanza’s `from` attribute.

Since this implementation of CheshiR uses an XMPP component, it must include a `from` attribute in all messages that it sends. Adding the `from` attribute is done by including `mfrom=self.xmpp.jid` in calls to `self.xmpp.send_message`.

### Updated Code

    def handleXMPPPresenceProbe(self, event) :
      self.xmpp.send_presence(pto = event["from"])

    def handleXMPPPresenceSubscription(self, subscription) :
      if subscription["type"] == "subscribe" :
        userJID = subscription["from"].jid
        self.xmpp.send_presence_subscription(pto=userJID, ptype="subscribed")
        self.xmpp.send_presence(pto = userJID)
        self.xmpp.send_presence_subscription(pto=userJID, ptype="subscribe")

    def handleMessageAddedToBackend(self, message) :
      body = message.user + ": " + message.text
      for subscriberJID in self.backend.getSubscriberJIDs(message.user) :
        self.xmpp.send_message(subscriberJID, body, mfrom=self.xmpp.jid)

View full source (4) | View original code (4)

## Example 14-6. (Page 223)

CheshiR IM server component with in-band registration support.

Note

Since the CheshiR examples build on each other, see previous sections for corrections to code that is not marked as new in the book example.

After applying the changes from Example 14-4 above, the registrable component implementation should work correctly.

Tip

To see how to implement in-band registration as a Slixmpp plugin, see the tutorial Creating a Slixmpp Plugin.

View full source (5) | View original code (5)

## Example 14-7. (Page 225)

Extended CheshiR IM server component implementation.

Note

Since the CheshiR examples build on each other, see previous sections for corrections to code that is not marked as new in the book example.

While the final code example can look daunting with all of the changes made, it requires very few modifications to work with the latest version of Slixmpp. Most differences are the result of CheshiR’s backend functions expecting JIDs to be strings so that they can be stripped to bare JIDs. To resolve these, use the `jid` attribute of the JID objects. Also, references to `"message"` and `"jid"` attributes need to be changed to either `"body"` or `"status"`, and either `"from"` or `"to"` depending on if the object is a message or presence stanza and which of the JIDs from the stanza is needed.

### Updated Code

    def handleIncomingXMPPMessage(self, event) :
      message = self.addRecipientToMessage(event["body"], event["to"].jid)
      user = self.backend.getUserFromJID(event["from"].jid)
      self.backend.addMessageFromUser(message, user)

    def handleIncomingXMPPPresence(self, event) :
      if event["to"].jid == self.componentDomain :
        user = self.backend.getUserFromJID(event["from"].jid)
        self.backend.addMessageFromUser(event["status"], user)

    ...

    def handleXMPPPresenceSubscription(self, subscription) :
      if subscription["type"] == "subscribe" :
        userJID = subscription["from"].jid
        user = self.backend.getUserFromJID(userJID)
        contactJID = subscription["to"]
        self.xmpp.send_presence_subscription(
            pfrom=contactJID, pto=userJID, ptype="subscribed", pnick=user)
        self.sendPresenceOfContactToUser(contactJID=contactJID, userJID=userJID)
        if contactJID == self.componentDomain :
          self.sendAllContactSubscriptionRequestsToUser(userJID)

View full source (6) | View original code (6)