20
Sat, Apr
5 New Articles

TechTip: Exploring GeoNames Web Services, Part III: Find Nearby Points of Interest

APIs
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

Use the procedure explained here to help your clients find the Points of Interest (POIs) near your place of business, just like a GPS device would!

 

While the previous tips of this series have been focused on retrieving information relevant to your company, this time it'll be a bit different: this one is for your clients.

 

Knowing beforehand that there's a nice restaurant or bar near your car dealership is useful when you go in for a small repair that won't take long. You can either find out for yourself or, if your dealership has a really nice service, its Web site or customer support line will be able to tell you. From a company's point of view, having additional information available about its locations (stores, offices, branches) might provide an edge over the competition.

 

This TechTip explains the "Find Nearby POIs" Web service from GeoNames in order to achieve that goal. Even though the Web service is provided by GeoNames, the data actually comes from OpenStreetMap. I recommend that you learn more about OpenStreetMap (it's a great open-source project) and read their copyright and license.

 

Let's start by looking at the Find Nearby POIs Web Service. Being a REST Web service, it is invoked by composing a URL (in which you include the GPS coordinates of the location) such as the one below:

 

http://api.geonames.org/findNearbyPOIsOSM?lat=37.451&lng=-122.18&username=demo

 

It will return an XML document with the POIs that are near the coordinates indicated:

 

<geonames>

  <poi>

    <name>Cook's Seafood</name>

    <typeClass>amenity</typeClass>

    <typeName>restaurant</typeName>

    <lng>-122.1795529</lng>

    <lat>37.4516093</lat>

    <distance>0.08</distance>

  </poi>

  <poi>

    <name>Starbucks</name>

    <typeClass>amenity</typeClass>

    <typeName>cafe</typeName>

    <lng>-122.1803386</lng>

    <lat>37.452055</lat>

    <distance>0.12</distance>

  </poi>

  <poi>

    <name>Safeway</name>

    <typeClass>shop</typeClass>

    <typeName>supermarket</typeName>

    <lng>-122.1787081</lng>

    <lat>37.4507461</lat>

    <distance>0.12</distance>

  </poi>

  <poi>

    <name>Akasaka</name>

    <typeClass>amenity</typeClass>

    <typeName>restaurant</typeName>

    <lng>-122.1809239</lng>

    <lat>37.4524367</lat>

    <distance>0.18</distance>

  </poi>

</geonames>

 

The <poi> element is composed of the following sub-elements:

 

  • <name>—The name of the point of interest (POI)
  • <typeClass>—The class of the POI, according to the OpenStreetMap Map Features classification
  • <typeName>—The type (or sub-class) of POI, again according to the OpenStreetMap Map Features classification
  • <lng>—The longitude coordinate of the POI
  • <lat>—The latitude coordinate of the POI
  • <distance>—The distance between the POI's coordinates and the ones indicated on the Web service invocation.

 

Now, examine the XML. This time, there's a new type of reply: instead of having only one set of similar data in the response XML (<timezone> on the first tip and <country> in the second), here we have multiple sets (the <poi> element repeats multiple times). In order to handle this, a slightly different approach is required in both the procedure's parameters and the data structure used on the XML-INTO opcode; they must have the ability of storing multiple instances of the same type of data. In other words, they must be arrays.

 

In the QCPYLESRC/RTVFNP_PR source member, I've defined a new data structure, t_poi, with a structure similar to the <poi> element and used it to define the XML-INTO data structure:

 

D GeoNames        DS                  Qualified                      

D   Poi                               LikeDS(t_Poi) Dim(C_MaxElems)  

D   Status                            LikeDS(t_Status)               

                                                                     

And this is the procedure's parameter that will pass the POIs back:

 

DP_Poi_DS         DS                  LikeDS(t_Poi) Dim(C_MaxElems)

 

I'll explain the rest of the procedure's parameters later. Now, notice the Dim(C_MaxElems). This turns the data structure into an array, which fits our needs, but it will require additional coding when passing the values from the GeoNames.Poi data structure to the P_Poi_DS parameter:

 

   For W_Idx = 1 to C_MaxElems;                                 

     If Geonames.Poi(W_Idx).TypeClass <> *Blanks;

       P_Poi_DS(W_Idx).Name = Geonames.Poi(W_Idx).Name;

       P_Poi_DS(W_Idx).TypeClass = Geonames.Poi(W_Idx).TypeClass;

       P_Poi_DS(W_Idx).TypeName = Geonames.Poi(W_Idx).TypeName;

       P_Poi_DS(W_Idx).Lng = Geonames.Poi(W_Idx).Lng;

       P_Poi_DS(W_Idx).Lat = Geonames.Poi(W_Idx).Lat;

       P_Poi_DS(W_Idx).Distance = Geonames.Poi(W_Idx).Distance;

       P_NbrElems += 1;

     Else;

       Leave;

     EndIf;

   EndFor;

 

Here, I'm looping through the GeoNames.Poi array until one of two things happens: either the last element in the array is reached or the current element of the array doesn't contain a POI. C_MaxElems is a numeric constant, set to 20 in QCPYLESRC/RTVFNP_PR. During my tests, I never got more than 10 POIs from the Web service, regardless of the GPS coordinates.

 

Now for the procedure itself: as usual, you'll be able to call it from an IF statement, because it returns *ON if something goes wrong. Here's an example:

 

If RtvPOIFrmGPS(P_Latitude : P_Longitude : P_Poi_DS: P_NbrElems:  P_ErrCode : P_ErrMsg ) = *Off;

  // Do something with P_Poi_DS and P_NbrElems

EndIf;

 

The procedure's parameters include the usual P_Latitude, P_Latitude, P_ErrCode, and P_ErrMsg that I used on the first two procedures. The specifics here are the P_Poi_DS and P_NbrElems. This last parameter contains the number of elements of the P_Poi_DS array that contain data. Even though the maximum number of elements of the array is set to 20 (see C_MaxElems), that doesn't mean you'll always get 20 POIs. Actually, depending on how precise your GPS coordinates are (i.e., how many "decimal places" your coordinates have), you might receive an empty array, in the worst-case scenario. As I said before, the maximum I got during my tests was 10 POIs, but I couldn't get a feedback from GeoNames or OpenStreetMap about the maximum number of POIs the Web service returns.

 

Finally, a quick look at the provided example in the QRPGLESRC/TST_FNPADD source member shows the usual orchestration of Web services, starting with an address (in this case, of the biggest mall in the United States, according to Wikipedia). For simplicity's sake, the example lists the name of only the first POI found, but it should be clear enough on how to use the P_Poi_DS array.

 

You can download the source code for this article here.

 

That's all for this TechTip. If you have any questions or suggestions, feel free to contact me!

 

The next TechTip of this series will demonstrate how the same Web service can have different sets of input parameters: the "Find Nearby Wikipedia" Web service can be used by passing the GPS coordinates or the postal code of the location you want to search about.

as/400, os/400, iseries, system i, i5/os, ibm i, power systems, 6.1, 7.1, V7, V6R1

Rafael Victoria-Pereira

Rafael Victória-Pereira has more than 20 years of IBM i experience as a programmer, analyst, and manager. Over that period, he has been an active voice in the IBM i community, encouraging and helping programmers transition to ILE and free-format RPG. Rafael has written more than 100 technical articles about topics ranging from interfaces (the topic for his first book, Flexible Input, Dazzling Output with IBM i) to modern RPG and SQL in his popular RPG Academy and SQL 101 series on mcpressonline.com and in his books Evolve Your RPG Coding and SQL for IBM i: A Database Modernization Guide. Rafael writes in an easy-to-read, practical style that is highly popular with his audience of IBM technology professionals.

Rafael is the Deputy IT Director - Infrastructures and Services at the Luis Simões Group in Portugal. His areas of expertise include programming in the IBM i native languages (RPG, CL, and DB2 SQL) and in "modern" programming languages, such as Java, C#, and Python, as well as project management and consultancy.


MC Press books written by Rafael Victória-Pereira available now on the MC Press Bookstore.

Evolve Your RPG Coding: Move from OPM to ILE...and Beyond Evolve Your RPG Coding: Move from OPM to ILE...and Beyond
Transition to modern RPG programming with this step-by-step guide through ILE and free-format RPG, SQL, and modernization techniques.
List Price $79.95

Now On Sale

Flexible Input, Dazzling Output with IBM i Flexible Input, Dazzling Output with IBM i
Uncover easier, more flexible ways to get data into your system, plus some methods for exporting and presenting the vital business data it contains.
List Price $79.95

Now On Sale

SQL for IBM i: A Database Modernization Guide SQL for IBM i: A Database Modernization Guide
Learn how to use SQL’s capabilities to modernize and enhance your IBM i database.
List Price $79.95

Now On Sale

BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$0.00 Raised:
$

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: