I want to create a weather app for my android phone but now I got stuck on the backend part of the app.
I have found a weatherservice where I can, for free, get detailed information about a certain location through their webservice. But they have stated in their rules that I am not allowed to poll their service with a high frequency. So I thought that I could create a webservice on my own that retrieve weatherinformation from the weatherstation that I found and then make it available through my webservice so that my app only make calls to my service.
the communication will be like below
MyApp <--> MyWebService <--> commercial webservice
the android app talks to MyWebService. And my webservice talks to the commercial service.
So I want MyWebService to do to things.
retrieve information from the commercial webservice once every hour and update my database
handle requests from my androidApp
My problem is that I know to little about web application and web services. I don't really know what language to choose for the webservice.
PHP with soap or REST looks like a good candidate for the second task. But I can't find any sample on how to handle the first task. Is there any easy way to tell the server to run my script once every hour?
I have been looking a litle into C# as well which would suit me a litle bit more as I am more used to C#. But the same question arise here. How do I handle the second task?
This is something that I wanted to write for a long time, but I feel totaly lost here.
Doing things "once an hour" (or more generally, scheduling tasks) from a web-only application is tricky for a number of reasons. It is much better in general to use the built-in mechanism of the operating system to perform scheduled tasks (e.g. cron under Linux, or Scheduled Tasks under Windows), or to write a service/daemon process that handles the updates.
Having said that, there is a fairly straightforward way to meet your requirement. You can cache the result of the commercial web service in your web application tier, along with a timestamp of the last time you retrieved the information. When a web request comes into your web service from your app, first check the timestamp of the cache. If the timestamp is less than one hour old, just returned the cached weather data. If the timestamp is more than an hour, call the commercial web service directly from there, write the result and the current time into your cache, and return the data you just got to the app.
PHP is certainly well-suited to this kind of task. Detailed instructions on how to do that are beyond the scope of a Stack Overflow question. Google for PHP and caching, try out some examples, and ask detailed follow-up questions if you get stuck.
Related
My goal is to build an application that can dynamically monitor my Stock Portfolio (Stock Options actually). So, I am building my business logic in a TDD approach using C# on .NET core. I haven't much thought about the interface because the following is true:
1) My broker is ETrade so I will have to authenticate and use their api for my position information
2) I need this application to run from 9:30 AM - 4:00 PM EST Monday - Friday
As I am nearing completion of my 1st MVP business logic, I am now starting to think about where I will delpoy the final solution and hence I am seeking the community for feedback.
I have heard, but not worked much with Microservices (AWS, Azure, etc.) so I'm not sure if that is the direction I want to look. (Also, I have a tight timeline and don't want to have to learn too much to get this thing deployed - but I am open to any solution). Excluding Microservices and the Cloud I have considered the following:
a) "I could run the program from a Console application"?
(answer) I would have to either:
(a) get a dedicated server to do or
(b) try to ensure that I can leave a laptop running at home or something, blah, blah
(conclusion) Both are plausible decisions.
b) "I could run the program as a Windows Service"
(answer) I would have to either
(a) (same as above)
(b) (same as above)
(conclusion) Both are plausible decisions.
c) "I could run the program as a Web Site"
(answer) I would have to either
(a) (same as above)
(b) (same as above)
(conclusion) Both are plausible decisions.
c) "I could investigate The Cloud (Microservices)"
(answer) ???
(conclusion)
So, in closing, basically, given the requirements of up-time between those hours and I would like to be able to access the app from any internet browser. I have logic that needs to ping various endpoints pretty much every minute during market hours. So I am not sure how I would handle this using a Web Application because if (by chance) the browser is closed, the Web Application stops running and thus would defeat my needs! Does the cloud help here? Maybe I should just use a Windows Service and make my logs accessible on the web. Or I deploy the TraderBot in a Windows Service and also build a Web Application to receive real-time intel from the TraderBot Windows Service / Logs / and-or DB? Not sure, but I appreciate any knee-jerk responses you all have!
I really like to connect pieces of tech to solve complex problems. Though it's not that complex.
Solution 1: Cloud-based, specifically on AWS
Use AWS Lambdas(Serverless compute) to hit the API to get prices or whatever info you are seeking and then store it in DynamoDb(A NoSQL DB). Use CloudWatch Rules(Serverless CRON job) to invoke your lambda periodically.
Then SPA Single page application to view values stored in DynamoDb. It can be a static website hosted on S3 also.
Or
A mobile app can also serve the purpose of viewing the data from DynamoDb.
Solution 2: Mobile-Only
Why not build the app purely for mobiles like iOS or Android. Check here I've coded one app just to track the price of different alt-coins of different exchanges.
With the mobile-only app, your app will fetch the prices periodically(Using alarms API in case of Android) and will store in its local database(SQLite in case of Android) and then you can open the app any time to see the latest values.
More solutions can be thought of, But I think above are a good approach for solving this problem rather than buying a VPS or blowing your laptop all 24X7 #ThinkCloud
PS: Initial thoughts only, Ask more to enhance the solution... :)
From what I know, Parse offers convenient communication stacks for various platforms such as iOS, so it is easy to build clients that use your web app.
But Parse also seems to be tightly integrated with Facebook. If you were to build a web app that does not need Facebook, but that may integrate with Facebook in the long term, is Parse the clear winner over deploying directly to AWS, or are there important disadvantages to consider?
As far as I understand their page Parse is a PaaS (platform as a service) provider like Heroku and others while AWS is a IaaS (infrastructure as a service) provider.
Pros for PaaS:
They care about the infrastructure
You build your app on an existing platform
For the start you don't need "ops-guys" as you don't do ops
You can take their knowledge and prebuilt tools for your advance
Pros for IaaS:
You have full control about the underlaying infrastructure
You can start with a greenfield and build what ever you want
You can use tools like Puppet / Chef / ... to control your servers
You don't have to pay for the additional stuff you get when using PaaS
(but have to pay your people for it)
So there is not a winner of this "battle" but you have to decide whether you want to use prebuilt tooling and give some independence for this or whether you want to have the absolute control over everything (nearly as you can't touch the hardware) and invest time and manpower into building your own tooling.
"Better, Faster, Cheaper.."
If you are pursuing mobile first strategy, Parse is a great tool for bootstrapping a mature, full web-presence from nothing more than an original beta app.
I dont have direct experience with AWS.
I have used Heroku/Parse integrating (very quickly) a stand alone mobile app with the back-end where the back end needs to cover following:
DB/persistence/noSql
Workflow - async tasks
REST API interface HTTP
Once the mobile app existed with only stubbed local data , Parse allowed a single engineer to build out ALL infrastructure mentioned above very quickly, taking the app from single user to multi-user with full DB and workflow that backs client side events with considerable server-side and cloud side business logic and process. Scaling related startup stuff that used to take weeks took only days.
The compression (time&money) when scaling up an app stack is really something. The Parse API did almost everything that i needed with one small exception (remuxing UGC media).
Personally, i abandoned the parse/android SDK in favor of a more robust REST API (threading on client-side and heavy HTTP activity ).
Developers used to Curl/REST dev stacks will take to Parse.
I am just getting started in web services using Lotus Notes. What I would like to be able to do is to create a web service that generates a sequential number. The code to generate the number is based on existing code we have used for some time within our databases (just straight lotus script, no web services). Basically there is a document that stores the next number, the next number is returned and is updated for the next call save conflicts are detected and the number is tried again if there was a issue saving the number.
I thought I might use a web service for to generate the number. So are web services processed sequentially or in parallel? Because if they are serial then I won't need to deal with two people trying to save the number at the same time.
Web services are a way for two systems to communicate with each other where they would not have a common language.
For example LotusScript agent connecting to a .Net server.
When creating a web service provider (server) on Domino you can code it in LotusScript or Java. The server then provides a WSDL file for the consumer (client) to write the code required to talk to that web service.
This tutorial should explain it better for you:
http://www-10.lotus.com/ldd/ddwiki.nsf/dx/Creating_your_first_Web_Service_provider_and_consumer_in_LotusScript_and_Java.
Now as for Domino. Web services run in order they are requested from the server. However there is no control to say "Don't start until Webservice X has finished".
You could also code this into an application but run the serious risk of deadlocks of memory/performance issues for other users unless you counter for that.
The Domino server can also be set to not run web services/agents in parallel. But again you risk the same issues.
If it is a unique ID then you could go by the UNID of the document you create from the web service. Or you can use #UNIQUE via an evaluate, but both only return text.
http://publib.boulder.ibm.com/infocenter/domhelp/v8r0/topic/com.ibm.designer.domino.main.doc/H_UNIQUE.html
From the Lotus Designer Documentation:
To enable concurrent Web services on a server, you must enable concurrent Web Agents on that server. Open the Server document you want to edit. Click the Internet Protocols - Domino Web Engine tab. Enable Run Web Agents concurrently.
The maximum number of concurrent Web service calls is determind by "Max concurrent agents"-setting. From the Lotus Administration Documentation:
Max concurrent agents Specifies the number of agents allowed to run concurrently. Valid values are 1 through 10. Default values are 1 for daytime and 2 for nighttime. Enabling a higher number of concurrent agents can relieve a heavily loaded Agent Manager, but also reduces the resources available to run other server tasks.
Lotus Notes Domino Version 8.5.x
Yes web services Will run in parrallel. But since you wrote that your code deals with save conflict, you should NOT have problem.
As in standard notes calls by 2 users: the 1st get the doc then the 2nd get the doc and save (speedy two) then first will get save conflict.
In conclusion yes it's parallel BUT it's not a problem.
I would have thought that they would by default run sequentially as asynchronous web agents is off unless you switch it on. So although it's a good design pattern to do 'safe' sequentially number if you only allocate a number via the web service and you haven't changed the asynchronous setting then you'll be fine
Let me also add:
Employ document locking to assure number uniqueness in sequential document numbering solution
There is a simple solution that avoids synchronicity considerations.
You should generate a temporary number using #Unique, then use a scheduled agent to assign sequential numbers in order of document creation, selecting only unprocessed documents using a properly constituted view. If you're not concerned about the order in which documents were created and only concerned that all numbers are unique, a view is not necessary, and you can just trigger the agent on unprocessed documents.
The temporary number can be used for reference temporarily until a proper sequential number is assigned.
When the scheduled agent runs, it should send authors confirmation with the correct reference number.
Or, you could export to DXL and get the sequence= attribute of the tag. This only works if you're accessing a single instance of the database, though. And the DXL export/XML import is a huge amount of overhead.
Unfortunately, I can't see a way to easily get the sequence number of the note from LotusScript NotesDocument. If you have an active support contract, you could open a Problem Management Report for a software enhancement request ("APAR", in IBM's parlance, though I do not know what its acronym expands to).
Good luck!
In our client application we need to get the time of the server. For this getTime() operation added to an existing web service on server which basically returns DateTime.Now (.Net environment).
At the moment there seems no other time related need other than current time.
But what methods can be added beside this? If you had such an experience or if you had to add some other methods later, please share your experience.
Note: I know, we can stick to YAGNI, but I want to know what other needs people face related to time web services.
Timezone information? (i.e. the timezone that the server is situated in..)
I need to be able to access a mySQL database from my iPhone, for both read and write ops. Instead of using MCPKit (due to security and speed considerations), I'd like to access the db through a separate service. The app is iPhone SDK, so I need to get data back in XML form, not as a web page.
I am trying to decide whether to write a Java web service (SOAP) to provide this link, or to just throw together a PHP script on the server side. I can create either solution, but I don't know enough to figure out the advantages/disadvantages of the choice. Please help; thank you!
If you're writing both the client and the server, and performance isn't a significant issue, then the primary remaining consideration is development time.
So, what tools do you have at your disposal? Which platform will allow you to do this with the least amount of work? If it's a toss-up between the two, then pick the one you're most familiar with.