Consuming HTTP Services in Python Transcripts
Chapter: XML services with requests
Lecture: Concept: Working with XML from Python
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0:02
Let's review working with xml in Python.
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We're not yet to the services part, but that's actually the easy part,
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it's working with xml itself that can sometimes be tricky;
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so here we've got a little fragment of the data that came
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from that Reed college course catalogue that was reed.xml,
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you can see we have a title, we have days, we have building, and room,
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and if we want to work with this, we go and import ElementTree,
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and just to make our lives easier, it wasn't technically necessary
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but it is better to create a named tuple
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which is more or less a class with fields only and no functions,
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which was all we really needed it was little data containers,
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and then we are going to parse that from the string representation of xml
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into the DOM, the object model,
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we are going to use the from string method on the ElementTree,
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and then we start writing xpath, queries against it,
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so here we are looping over the find all of the courses, and for each course,
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or each really node that we find in the xml document, we are going to run
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a set of subqueries on that document, so we are going to query for the title,
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for the place/building, place/room,
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and then in this example we're also getting the days that it runs.
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Then if we want the courses that are held in Eliot hall, or a building,
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all we have to do is write a little list comprehension
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say give me the course for course in courses,
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these are the transformed named tuple types, where the building=eliot.
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Boom, it's done, it's worth considering the trade-off of xml versus json
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and how it relates back to Soap services.
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So Soap is a much more strict and honestly convoluted protocol
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than simple xml exchange.
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So Soap has envelops and headers and a bunch of namespaces,
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and certain ways in which things must be structured,
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and xml is just much more general, there can be simple xml or complicated xml.
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So what we are doing and what we are going to do, for this section,
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is all about just working with plain xml data, not Soap services,
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Soap services require tons of tooling and we'll work on that later, right,
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we'll see that Python actually has some decent answers to the Soap story
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if you must use those services,
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but in this case, we are just working with straight xml.
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So, we are just focused on working with xml by itself, now, if you get the choice,
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if you get to decide whether you have an xml service or a Json service,
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choose, Json, it much more closely matches the way data is represented in Python
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and the way it's represented in Javascript,
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so if you are building a web app and it's got a Javascript front end
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and a Python back end, Json all the way,
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but, consuming xml is still not too bad as we've seen.
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So, let's go look at another example.
