This tag describes a particular context in the Botscript.

It can contain:

Summary

Each context in the Botscript contains a part of the dialog.

There is one root context in each Botscript that contains all the rest of the Botscript.

<context> <!-- The root context -->
  <pattern name="MyPattern" value="*"/> <!-- A general pattern -->
  <input>
    ...
    <context> <!-- A nested context -->
      ...
    </context>
  </input>
</context>

  You can think about a context as a "hole" where the user’s input text falls. It falls through all inputs inside the context until a pattern in one of the inputs matches this text. Then one of the nested contexts extends the root context and then the user’s input will fall through it.

And what if none of the inputs contains appropriate pattern that would match the user’s text? In such case an empty response will be returned.

Context Extending

Each time the context encounters an appropriate input containing a pattern that does match, one of the nested contexts extends the root context. And the next user’s request will be matched through such an extended context.

For example, if your context looks like the following:

<context>
  <input pattern="* (weather|forecast) [$Date]">
    <output value="The weather is fine!"/> <!-- Nice response! -->

    <context id="weather_context">
      <input pattern="* $Date"/>
      <output value="It will be much better!"/>
    </context>
  </input>
</context>

When user asks something like “What is the weather today?”, our bot will respond “The weather is fine!”

Then Zenbot extends the root context by the inner one with the id having value weather_context. It means that the pattern * $Date will be added to the root context, so the user can ask “And what about tomorrow?”. And get back a response “It will be much better!”

Then he/she can ask again “And next Monday?” — and our bot will understand him/her correctly. It is so because the root context is already extended and the bot understands what we are talking about. At the same time the user can of course ask again “Tell me the forecast”, and the bot will process it.

  Thus instead of a final state machine paradigm, Zenbot continuously extends the root context for dialog branching implementation.

Please read more about context management in the dedicated chapter.

Sometimes you need to give an exclusive priority for a given context to catch the next user’s request ignoring the rest of the root context.

Such technique is called a “modal context”. Let’s look at it:

<context> <!-- A regular context -->
  <input id="greeting" pattern="* remind [me] [to] $Text">
    <output value="Done!" if="full($Text)"/>

    <context if="empty($Text)" modal="true"> <!-- A modal context -->
      <output value="What would you like me to remind you about?"/>

      <input pattern="$Text">
        <output value="Done!"/>
      </input>

    </context>
  </input>
</context>

Here we have implemented a very simple reminder dialog. The user can say “Remind me to call mom this evening”. In this case the bot will respond with “Done!” output.

But what if the user didn’t provide the reminder text? Well, in such case our bot will ask him/her “What would you like me to remind you about?” And the next user’s request must be interpreted as the reminder text, even he/she says “Remind” again.

This is because the nested context is a modal context. So it ignores everything except the inner inputs and always matches the user’s input through them.

  A modal context will be canceled once the next request has been processed. Thus the third request will be processed through the root context.

General Patterns

You can define a set of patterns inside a context tag. Those patterns won’t be recognized as patterns of an input.. Such patterns are called General patterns, and their main purpose is to define reusable patterns which could be used inside other patterns.

<context>
  <pattern name="Fruit" value="(apple*|orange*)"/> <!-- A general pattern -->
  <input>
    <pattern value="* (want|wanna) * $Fruit"/> <!-- Uses the general pattern -->
  </input>
</context>

Context ordering

The context can contain patterns that are dependant from the patterns from another context that is described in different Botscript file.

Zenbot doesn't resolve such dependencies while loads your Botscript. That is why you have to declare the order of contexts loading. This helps Zenbot to load the most common contexts and its' patterns first.

In the root context define the “order” attribute with appropriate integer value. In the example below you can see how to declare two contexts with dependant patterns.

<context order="0"> <!-- This context declares a common pattern that can be used from another context -->
  <pattern name="CommonPattern" value="*"/>
</context>
<context> <!-- This context in the different file will be loaded after the context above -->
  <input pattern="* $CommonPattern *"></input>
</context>

Attributes

Controls the modality of a context. You can set it to true to make a particular context modal.

Read about modal contexts above.

id attribute

Each context (except the root context) has its own unique string identifier. You can define your own id attribute like this:

<context id="my_context">
...
</context>

Each time a user’s request text matches a pattern, one of the nested contexts will be fetched by Zenbot and its identifier will be returned as a part of the response.

You can also use this identifier to reference another context from an input:

<context id="my_context">
  <input pattern="*">
    <context id="my_context"/> <!-- Make "my_context" context active if this input matches the user’s input -->
  </input>
</context>

  Note that the `id` attribute is optional. You do not have to define it if you do not need to use it. In such case Zenbot will generate it automatically.

order attribute

If you need to declare some common patterns in one file and use them from another files, just declare the order of context loading to prevent Zenbot from loading of dependant context first.

This attribute can contain any integer value. 0 means the context will be loaded first. You can omit this attribute as well. This means that this context will be loaded afterwards.

channel attribute

Define channel IDs here to activate this context only for requests from the particular channels.

if attribute

When Zenbot decides which of the nested contexts should be activated, it looks in the optional if attribute to find a condition expression to evaluate.

If such a condition is defined, Zenbot evaluates it with a bunch of existing variables. If this expression returns 1, Zenbot extends the root context with this one. Otherwise Zenbot keeps looking through nested contexts further.

<input pattern="(hi|hello) *">
  <context id="empty_name" if="empty($UserName)">
    <output value="Hi! What is your name?"/>
    ...
  </context>
  <context id="name_is_present">
    <output value="Hello $UserName!"/>
    ...
  </context>
</input>

In this example when user says something like “Hello there”, Zenbot looks through the nested contexts. The first one (with the id set to empty_name) has a condition empty($UserName) which means “Select me if there is no UserName variable or if it is empty”. Zenbot evaluates it with all variables it has for now. And if this expression returns 1 (there is no UserName variable yet), Zenbot stops looking through the context and selects empty_name and returns “Hi! What is your name?” as output.

Otherwise Zenbot continues to look through the contexts and sees the name_is_present context that doesn’t have any condition. Well, good choice — Zenbot will select it and, as a result, return “Hello Joe!” string (if, for example, the UserName variable contains “Joe”).

Read more about expressions in this chapter.

lang attribute

Since Botscript is language-independent, you can define the language code of the user request to activate the particular context. If the user’s language is not equal to the defined language, the context will be skipped automatically.

Such attribute is the same as a conditional expression like $req_lang == "en".