Homework 6: Server-side Scripting


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In this exercise, you are asked to create a webpage that allows you to search for
weather information using the Google Geocode and Forecast.io APIs, and the results
will be displayed in tabular format.
2.1. Description of the Search Form
A user first opens a page, called forecast.php (or any valid web page name), where
he/she can enter an address (street, city, and state) and select the temperature unit
(Fahrenheit, Celsius). An example is shown in Figure 1. The State field includes a list of
all US states, which are provided in section 3.4. Also, The form should include a
forecast.io disclaimer, linking to ‘http://forecast.io/’.
Figure 1: Initial Search Screen
The search form has two buttons:
● Search button: This button validates whether the user provided values for street
address, city and state. The validation should be implemented in a JavaScript
function. If the user did not enter one of the data items, then an alert should be
shown with an appropriate message prompting the user to provide complete
information. An example of the alert is shown in Figure 2, and an example of
valid input is shown in Figure 3. Once the user has provided valid data, your
script should send a request to your web server for forecast.php (or whatever
your valid web page name is) with the form data. You can use either GET or
POST to transfer the form data to the web server. A PHP script will grab the data
and send it to the Google GeoCode and Forecast.io web services in sequence.
● Clear button: This button must clear the result area, all text fields, unselect the
State value and reset the “Degree” field to its default value of Fahrenheit. The
Clear operation is done using a JavaScript function.
Figure 2: An Message Error When Proving Incomplete Address (e.g., the values of city
and state fields are missing)
Figure 3: An Example of Valid Input
2.2. Displaying Results
In this section, we explain how to use the form data to construct web services calls to
Google GeoCode and Forecast.io APIs and display the result in your page.
The PHP script (forecast.php or whatever your valid page name) will use the
address information (street, city, and state) to construct a web service URL to query the
Google Geocode API appropriately:
How to create a Google API key is explain in section 3.2. The response of this URL is
an XML-formatted object. One key piece of data returned is the latitude and longitude
values for the given address. Figure 4 shows an example of the XML returned in the
Google GeoCode web service response. You will see in the next step that you must use
the extracted latitude and longitude to look up the weather for a given location.
Figure 4: A Sample Result of Google GeoCode Query
Next, using the latitude and longitude values, another web service URL needs to be
constructed to query the Forecast.io API to get the weather information for the given
location such as:
When constructing the Forecast.io web service API call, you should provide five
● The first parameter is your Forecast.io API key (a.k.a. the Dark Sky API key).
How to create this key is explained in section 3.1.
● The second and the third parameter are the latitude and longitude values which
are extracted from the XML-formatted data returned by the Google Geocode API.
● The name of fourth parameter is units. The value of this parameter is either “us”
or “si”. If the temperature is in degree Celsius, units=si and if the temperature is
in degree Fahrenheit, units=us.
● The name of the fifth parameter is exclude. The value of this parameter is “flags”.
The response from a query of the Forecast.io web service is a JSON-formatted object.
An example of a returned JSON-formatted object from the Forecast.io API is available
Figure 6 shows part of this file. You need to parse the returned JSON-formatted object
and extract some fields. After extracting the data, the PHP script should display the data
in a tabular format below the search form. A sample output is shown in Figure 7.
Figure 6: Part of Sample JSON-formatted object returned from Forecast.io API call
Figure 7: Search Result
You need to map the data extracted from the result of the Forecast.io API call to your
table output using the following table:
Table Column Data from result of Forecast.io API call
Table Header The weather condition is the value of
summary in the currently object. The
weather temperature is the value of
temperature in the currently object. The
temperature should be printed in integer
format. Then, display an icon describing the
weather condition. The displayed icon
depends the value of icon in the currently
● icon value = “clear-day” → display
● icon value = “clear-night” → display
● icon value = “rain” → display
● icon value = “snow” → display
● icon value = “sleet” → display
● icon value = “wind” → display
● icon value = “fog” → display “fog.png”
● icon value = “cloudy” → display
● icon value = “partly-cloudy-day” →
display “cloud_day.png”
● icon value = “partly-cloudy-night” →
display “cloud_night.png”
The images are available at http://csserver.usc.edu:45678/hw/hw6/images.
The Weather Icon must be displayed, and
the alt text and title must be the text of the
weather condition.
Precipitation The value of precipIntensity in the currently
object. It is possibly one of the following
values {0, 0.002, 0.0017, 0.1, 0.4}.
● precipIntensity value = 0 → display
● precipIntensity value = 0.002 →
display “Very Light”
● precipIntensity value = 0.017 →
display “Light”
● precipIntensity value = 0.1 → display
● precipIntensity value = 0.4 → display
Chance of Rain The value of precipProbability in the
currently object. You should multiply the
value by 100 and display the percentage “%”
Wind Speed The value of windSpeed in the currently
object. The value should be displayed in
integer format. The unit is “mph”.
Dew Point The value of dewPoint in the currently
object. The value should be displayed in
integer format.
Humidity The value of humidity in the currently object.
You should multiply the value by 100 and
display the percentage “%” character.
Visibility The value of visibility in the currently object.
The value should be displayed in integer
format. The unit is “mi”.
Sunrise The value of sunriseTime is the first object
of data array in the daily object. The value is
a Unix timestamp so it needs to be
converted to the “two-digits-hour:two-digitsminute AM/PM” format. The hour should be
in 12-hour format. Example is 01:15 PM.
Sunset The value of sunsetTime is the first object of
data array in the daily object. The value is a
Unix timestamp so it needs to be converted
to the “two-digits-hour:two-digits-minute
AM/PM” format. The hour should be in 12-
hour format. Example is 01:15 PM.
In summary, the search mechanism to be be implemented behaves as follows:
● Based on the input data in the search form, construct a web service URL to
retrieve the XML-formatted output from the Google GeoCode API.
● Parse the returned XML and extract the latitude and longitude values.
● Call the Forecast.io API (latitude and longitude are parameters in the web service
URL) and retrieve the JSON-formatted output.
● Parse the returned JSON-formatted output and extract the weather information.
● Display the weather information in tabular format.
2.3. Saving Previous Inputs
In addition to displaying the results, your page should maintain the provided values to
display the current result. For example, if one searches for “Street: 3025 Royal St, City:
Los Angeles, State: CA”, one should see what was provided in the search form and the
corresponding results. It follows that you need to keep the whole search box/input fields
and buttons even while displaying results/errors.
3. Hints
3.1. How to get Forecast.io API Key
Go to https://developer.forecast.io/. Click on “Register”. You should fill out the form as
shown in Figure 9. The API Key (Dark Sky API key) is displayed as shown in Figure 10.
Copy this key as you will use it in the Forecast.io web service API call.
Figure 9: Forecast.io Registration Form
Figure 10: Forecast.io Application Key
3.2 How to get Google API Key
To get a Google API key, please follow these steps
 Go to the Google Developers Console
 Create or select a project.
 Click Continue to Enable the API.
 Go to Credentials to get a Server key (and set the API Credentials).
3.3. Parsing XML files in PHP
You are free to choose any XML parsing library, but we recommend the SimpleXML
library. The SimpleXML library provides a simple way of getting an XML element’s
name, attributes, and text. As of PHP 5, the SimpleXML library functions are part of the
PHP core. No installation is required to use these functions. The following two tables
show a set of functions which you may use. For more detailed information, please read:
● http://www.w3schools.com/php/php_xml_simplexml.asp
● http://php.net/manual/en/book.simplexml.php
● http://www.w3schools.com/php/php_ref_simplexml.asp
PHP 5 SimpleXML Functions
Function Description
__construct() Creates a new SimpleXMLElement object
addAttribute() Adds an attribute to the SimpleXML element
addChild() Adds a child element the SimpleXML element
asXML() Formats the SimpleXML object’s data in XML (version
attributes() Returns attributes and values within an XML tag
children() Finds the children of a specified node
count() Counts the children of a specified node
getDocNamespaces() Returns the namespaces DECLARED in document
getName() Returns the name of the XML tag referenced by the
SimpleXML element
getNamespaces() Returns the namespaces USED in document
registerXPathNamespace() Creates a namespace context for the next XPath query
saveXML() Alias of asXML()
simplexml_import_dom() Returns a SimpleXMLElement object from a DOM node
simplexml_load_file() Converts an XML file into a SimpleXMLElement object
simplexml_load_string() Converts an XML string into a SimpleXMLElement
xpath() Runs an XPath query on XML data
PHP 5 SimpleXML Iteration Functions
Function Description
current() Returns the current element
getChildren() Returns the child elements of the current element
hasChildren() Cheks whether the current element has children
key() Return the current key
next() Moves to the next element
rewind() Rewind to the first element
valid() Check whether the current element is valid
3.4 Parsing JSON-formatted data in PHP
In PHP 5, you can parse JSON-formatted data using the “json_decode” function. For
more information, please read http://php.net/manual/en/function.json-decode.php.
To read the contents of a JSON-formatted object, you can use the “file_get_contents”
function. Because in this homework the JSON-formatted object is retrieved using the
HTTPS protocol, your Apache server should be configured with a PHP compiler
enabled with Curl and OpenSSL as described in HW#5.
3.4. List of US States and Their Two-Letter Abbreviations
Two-Letter Abbreviation State
AL Alabama
AK Alaska
AZ Arizona
AR Arkansas
CA California
CO Colorado
CT Connecticut
DE Delaware
DC District Of Columbia
FL Florida
GA Georgia
HI Hawaii
ID Idaho
IL Illinois
IN Indiana
IA Iowa
KS Kansas
KY Kentucky
LA Louisiana
ME Maine
MD Maryland
MA Massachusetts
MI Michigan
MN Minnesota
MS Mississippi
MO Missouri
MT Montana
NE Nebraska
NV Nevada
NH New Hampshire
NJ New Jersey
NM New Mexico
NY New York
NC North Carolina
ND North Dakota
OH Ohio
OK Oklahoma
OR Oregon
PA Pennsylvania
RI Rhode Island
SC South Carolina
SD South Dakota
TN Tennessee
TX Texas
UT Utah
VT Vermont
VA Virginia
WA Washington
WV West Virginia
WI Wisconsin
WY Wyoming
4. Files to Submit
In your course homework page, you should update the HW6 link to refer to your new
initial web page fro this exercise. Also, Submit your files (likely only a single .php file)
electronically to the csci571 account so that they can be graded and compared to all
other students’ code via the MOSS code comparison tool.
All discussions and explanations in Piazza related to this homework are part of the
homework description. So please review all Piazza threads before finishing the