Joe Conley Tagged api

Swagger2Postman

Thu, 14 May 2015 00:00:00 +0000

I’ve recently been working on a Swagger-documented API where it’s been necessary to test the API endpoints in different environments. While Swagger UI is a simple, powerful tool for testing APIs, it doesn’t streamline well across multiple environments, nor does the UI allow for testing certain edge cases (i.e. what response will I get if I omit a required parameter?). However, Postman is very well-suited for both of these use cases, and so I’ve built a library called Swagger2Postman to convert Swagger docs into a Postman JSON collection.

Code - https://github.com/josephpconley/swagger2postman

Live Demo - http://app.josephpconley.com/swagger2postman

It only works with the Swagger 1.2 specification as of now so if you have any feedback or want to see it work for Swagger 2.0, let me know in the comments section here or on the project’s issues page. Thanks!

Everything is a Function

Mon, 26 Jan 2015 00:00:00 +0000

I’ve been working on a platform that would help free us from our dependence on apps. I’m hoping this ends up being a horizontal tool with a combinatorial number of use cases (hence the name DataCombinator). The main idea is to turn all digital interactions into simple functions (a la Excel) which can be composed to do cool stuff.

Here are the main concepts you need to know to understand how to execute and compose these functions

HTTP methods/requests and APIs (tutorial)
JSON (tutorial)
JSONPath (tutorial)
Handlebars.js for templating (tutorial)

That’s it. Composing functions is as easy as writing a sequence of commands (separated by semi-colon). Each function will return a valid JSON value, which will be passed to the context of the subsequent function. ~~The "current" JSON value can be accessed using the `_` character, and can also be used in argument strings using the Handlebars.js syntax.~~

UPDATE As I was going through some various examples it became clear to me that I needed both the most recent JSON value as well as past ones, so to that end I’ve modified the scripting language to use this as the current JSON value and _ to represent the array of all results in the script (with the 0th entry being the JSON value representing arguments passed to the script). I’ve updated the examples below accordingly.

Examples

To quote George R. R. Martin, “Words are wind”, so let’s look at some actual code. You can test them out and see the full list of available functions here. If you’re confused by any of the following examples, try out the worksheet as each function call result is shown.

Weather Alerts

Here’s an example of a custom weather alert service (one of the most popular IFTTT recipes).

This script does the following:

Performs a geo lookup using Google Maps to get the geocoding details of the address we’re interested in (in this case my office address).
- I added a Handlebars.js helper called urlEncode to facilitate things like url encoding
Navigates the result to find the latitude and longitude
Gets the short-term weather forecast from Forecast.io (sign up to get your own api key) using the lat and long from the previous call (using Handlebars to pass the values)
Sends an SMS message to my phone if it’s below 40

Pretty straightforward. The beauty of this is we can customize it to our preferred notification channel, and could easily swap out the SMS call with e-mail or Twitter.

Auto-generate RSS based on website updates

Despite the demise of Google Reader, I’ve always been a big fan of RSS. It tends to be a less noisy channel of information than social media, allowing for less frequent but longform communication. This example checks the AV Club for reviews of new episodes for a given show (I chose game-of-thrones-experts for this example, you’ll have to inspect the URL for your show) and generates an RSS feed.

Performs a web request to get the html source code of the webpage
Performs an XPath query to extract the HTML elements we need (and implicitly converts to JSON)
Uses the resulting JSON to build an RSS xml file from a Handlebars.js template

This has some more advanced concepts like XPath (not to mention knowing proper RSS formatting), but the script is still relatively easy to understand.

Website monitoring

As an owner/maintainer of a few websites, it’s important to know when any of them go down. There are several free services that will do this for you, but what if we wanted a customized view into our website uptime? Let’s write a script that monitors a really cool webapp you can use to track your golf scores and handicap, SwingStats

Performs a web request to the site we’re monitoring
Save the response info in a MongoDB database collection
If the status is not 200 (OK), then send an e-mail

This not only handles notifications but saves website data in a database (MongoDB). We can then build a separate script to access this data and calculate uptime percentage for SLA purposes.

Next Steps

I hope these examples were interesting. DataCombinator will soon have the ability to save scripts, expose them as API endpoints, and schedule script execution on a specific time interval using Cron expressions. The next version willl also expose your favorite social network functions, which could lead to things like one massive interleaved activity stream for all of your social media sites. If you’re interested in updates, follow along on the DataCombinator tag or sign-up for email updates.

Apps are Dead

Mon, 08 Dec 2014 00:00:00 +0000

No, apps aren’t dead (yet). But they should be. More precisely, I believe the concept of managing the bits and bytes of one’s digital life into 95 different silos has become untenable. Simple activities like communicating with friends should “exist” in one place. All of my documents should “live” in one place (my current company is working on solutions for that). I don’t mean to say that only one social network or one document storage site should prevail, but that similar services should be aggregated into one virtual, uniform experience for the end user.

What’s the alternative to a fractured digital experience? I can’t say for sure, but I’ll bet APIs will be involved. APIs allow the composition of functionality from multiple services while still mainitaining fine-grained access/control/security over the individual interactions. Viewing today’s popular applications as a menu of functions (i.e. API endpoints), it becomes natural to want to stitch these functions together in interesting ways. One such example of an API-driven, aggregator platform is Hootsuite. Their service allows reading activity streams from multiple social media sites, posting to multiple sites, and other common functionality. While this platform isn’t perfect (e.g. I can’t interleave multiple streams into one stream), it’s certainly a good start.

APIs have been around for a while now, so why aren’t API-driven aggregator platforms more popular? App companies themselves are likely to blame. LinkedIn recently disabled API access to a Philadelphia-based startup, perhaps seeing them as a threat (the startup has since pivoted without losing customers). Netflix shut down its public API last month for most developers. Facebook and Twitter have also had several high-profile denials of third-party applications as well.

Are app companies justified in their selectiveness over API access? In most cases, yes. Their data and functionality are typically their core competency, so why give it away for free/cheap? Their incentives, then, need to be realigned. There needs to be a platform which gives these companies an incentive to offer greater or even unfettered access. Then technology companies can focus on being service providers (via API and other channels), and not necessarily worry about being application providers.

I’m not sure what that platform is or what it looks like, but I’m trying to build it. Yes I know, it’ll probably end up being just another app (I thought those things were dying?), but building apps is what I know, so bear with me. Stay tuned for more details.

Query JSON/XML/CSV using SQL

Tue, 13 May 2014 00:00:00 +0000

Ever wish you could use your favorite query language across different data formats? Or get query results in several formats (XML, JSON, and CSV/XLS)? Then check out DataCombinator’s new query engine.

Data sources

You can copy and paste structured data manually, point to a URL, or connect to a database directly (H2, MongoDB, MySQL, or PostgreSQL). The engine hasn’t been optimized yet to handle large documents or tables so please be mindful.

Query languages

The engine supports JSONPath (powered by my open-source Play library), XPath and SQL. You can use any of these languages to query data in any of the JSON, XML or CSV formats. Since JSONPath and XPath are fairly similar and straightforward, the more interesting use cases tend to involve SQL.

SQL

The FROM CLAUSE isn’t necessary as the query only applies to one “table”, that is, the data being queried. For SQL to work against JSON, the JSON must be an array of objects, e.g.

[
   {
      "id":1,
      "name":"Joe"
   },
   {
      "id":2,
      "name":"Janine"
   }
]

If the objects in the array have nested levels, each object will be flattened, and the keys concatenated with an “_”, e.g.

[
    {
        "id": 1, 
        "name": "Joe", 
        "address" : { 
            "street" : "123 Main St.", 
            "city": "Springfield", 
            "state": "PA"
        }
    }
]

would be flattened to

[
   {
      "id":1,
      "name":"Joe",
      "address_street":"123 Main St.",
      "address_city":"Springfield",
      "address_state":"PA"
   }
]

Similarly, an XML must be in a “table format” in order to handle a SQL query, e.g.

	<table class="ui table">
		<row>
			<id>1</id>
			<name>Joe</name>
		</row>
		<row>
			<id>2</id>
			<name>Janine</name>
		</row>
	</table>

Supported SQL functions

The engine supports basic single-table query functionality (no self joins yet) with simple clauses (WHERE, GROUP BY, and ORDER BY) and a few basic aggregation functions (COUNT, MIN, MAX, SUM). I’ll be working to expand upon this, so if you have any requests let me know.

Query results

The query engine outputs results in JSON, XML, and CSV/HTML Table/Excel if the resulting structure can be converted to a table structure.

Examples

Here’s a few examples where I’ve found the query engine helpful.

ESPN APIs - JSON

ESPN has released a variety of APIs that allow developers to access headlines and basic team statistics. You’ll need to create a free account and register for a key, at which point you’ll have immediate access to the Public APIs.

So for example, if I wanted to find out stats on my beloved Philadelphia Phillies, I would enter http://api.espn.com/v1/sports/baseball/mlb/teams?apikey=MY_API_KEY as the URL in DataCombinator. Using the JSON Raw tab, I can see the pretty printed response, and quickly search on Phillies to find their id of 22. Using this id, I can get the latest news on the Phightins by using the URL of http://api.espn.com/v1/sports/baseball/mlb/teams/22/news?apikey=MY_API_KEY. I can then use JSONPath to only include the part of the response I want. For example, if I just want all the latest headlines associated with the Phillies, I take a quick look at the structure and apply the $..headline JSONPath query to return an array of headlines:

[
    "Mets end 5-game skid, rally past Phils 5-4 in 11",
    "Howard, Rollins lead Phillies past slumping Mets",
    "Byrd's double lifts Phillies over Mets 3-2 in 11",
    "The base: Approach at your own risk",
    "Phillies fall to hot-hitting Blue Jays in 20,000th game",
    "Adam Lind activated by Blue Jays",
    "Mark Buehrle posts MLB-best sixth win as Blue Jays rock Phillies",
    "Blue Jays edge Phillies on sac fly in 10th after blowing 5-run lead",
    "Happ stifles Phillies, Blue Jays win 3-0",
    "Hernandez outduels Gonzalez, Phillies edge Nats"
]

Weather Data - XML

OpenWeatherMap.org provides a free weather API which returns data in XML format. For example, if I wanted to get the current weather in my hometown of Springfield, PA, I could use the URL

http://api.openweathermap.org/data/2.5/weather?q=Springfield&mode=xml&units=imperial

to get an XML document back. I could then query the document using XPath to get just the temperature via //temperature.

<temperature max="71.52" min="71.52" unit="fahrenheit" value="71.52"/>

OpenData - CSV

Public institutions are starting to embrace open data practices, enabling civic-minded hackers to build useful applications that provide a public service. In this spirit, the city of Philadelphia has made various data sets available for public consumption. Most of these data sets are in CSV format. We’ll take one such data set, phl-site-stats, and use the Raw url from Github to query it (I picked this dataset as it’s relatively small).

We’ll take a look at the latest month’s stats found at https://raw.githubusercontent.com/CityOfPhiladelphia/phl-site-stats/master/SiteStats0514.csv. Without entering a query, we would get the entire data set in the results. One point to note is that the query engine will try to convert strings to numbers, making it easy to query based on certain conditions. If we wanted to view the most popular sites for phila.gov, we would simply enter a query of

select * order by page_count desc

Or we could get the total number of unique hits for the month of May

select sum(unique_page_count)

Next steps

This query engine will be the foundation of DataCombinator’s platform of data collection and composition tools. Our next step is to not only host structured data via API endpoints, but to also combine multiple datasources into one document (which in turn would be hosted as well!). If you’re interested in learning more, sign up for e-mail updates or follow us on Twitter @DataCombinator.

JSONPath Library for Play

Tue, 15 Apr 2014 00:00:00 +0000

I’ve been working on a platform that transforms, composes, and serves data. As part of this effort, I’ve developed a library for Play that performs a JSONPath query on a Play JsValue. You can learn about JSONPath by reading Stefan Goessner’s blog post on the subject.

I use Gatling’s jsonpath library to parse the JSONPath expression. I then fold over the tokens, performing a pattern match on each to construct the apporpriate JsValue. This parser supports all queries except for queries that rely on expressions of the underlying language like $..book[(@.length-1)]. However, there’s usually a ready workaround as you can execute the same query using $..book[-1:].

Example

Here’s a scala worksheet which traces the examples on Stefan’s post:

Deviation from JSONPath

One conscious choice I made as far as deviating from JSONPath is to always flatten the results of a recursive query. Using the bookstore example, typically a query of $..book will return an array with one element, the array of books. If there was another book array somewhere in the document, then $..book will return an array with two elements, both arrays of books. However, if you were to query $..book[2] for our example, you would get the second book in the first array, which assumes that the $..book result has been flattened. In order to make recursion easier and the code simpler, I always flatten the result of recursive queries regardless of the context.

If you have any questions, comments, or suggestions please let me know. I hope to be introducing an early iteration of my data platform shortly so stay tuned!

Building better APIs with Play!

Tue, 04 Mar 2014 00:00:00 +0000

This is the technical companion to my Point.io post, Building better APIs with Play!. Herein lies coding examples galore!

RESTful Architecture - Routing

The routes file of a Play app allows you to define the HTTP verb, the route path/pattern, and the corresponding method from the controller. In addition to denoting basic path variables, you can also use regular expressions to match on specific routes (i.e. xml or html formats for example). What’s great about this approach is this file is compiled along with the source code, so any mistakes like an incorrect controller method or invalid HTTP verb will be caught and thrown at compile time.

Action composition

We define two types of custom actions: atomic and composed. Atomic actions can be used stand-alone or as building blocks to be composed with other actions. We use the following pattern for building an atomic action.

The object allows us to use the action by itself, and the case class allows us to compose this action with other actions.

A composed action is strictly syntactic sugar, making it more convenient to combine behaviors and keeping the controller code more concise. We define composed actions using just an object.

Filters

Filters are handy for cross-cutting concerns. We’ve had one use case where it was necessary to modify every JSON response with links to metadata. We achieved this using a filter and the Play Enumeratee library

JSON - Global messaging

Building an effective API requires being responsive to users in a comprehensive manner. All concievable events should be handled appropriately, such as incorrect requests from the client or internal server errors. Creating a Global object allows you to generically craft responses to handle these situations. We define methods to handle events like internal errors, route not found, or a bad request.

Conclusion

Play is well-equipped to handle the nuances of API development and maintenance. We’re pleased with the stability and performance we’ve seen thus far and are looking forward to continuing down this path of reactive goodness.