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Andrea Magni

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Everything posted by Andrea Magni

  1. I would but, unfortunately, I am lacking time and trying to spend as much time as possible adding new features (i.e. the new Devart UniDAC intregration and the Delphi-Cross-Socket support). Please ask if you need specific help. Sincerely, Andrea
  2. Andrea Magni

    The 9 Hints in MARS

    @Yaron are you using the master or develop branch? I can't see hints/warnings using the develop branch. Sincerely, Andrea
  3. Hi @Chau Chee Yang, I've never seen errors compiling this package. Which branch are you using (master or develop)? Isn't this equivalent to set -LUDesignIDE in the Compiling options? I've never been a package addicted. 😉 Sincerely, Andrea
  4. Hi @Chau Chee Yang Fixed, thanks: https://github.com/andrea-magni/MARS/commit/c9a0d1d75a97b40a56258a6694ae6313107efd98 If you like to be mentioned in the project, feel free to open issues on Github for this kind of problems: your contribution would be public then. For the moment, I've added a comment with a link to this thread. Sincerely, Andrea
  5. Andrea Magni

    GZip compression in MARS

    Frank Lauter suggested me to implement chunking in MARS but I haven't done it yet. I guess one should implement some sort of caching in order to avoid continuously gzipping the same content just to serve a specific chunk to the client. Would be very interesting to cover this as it may result in a great performance boost for large data transfers. Sincerely, Andrea
  6. Andrea Magni

    GZip compression in MARS

    Hi @Bjørn Larsen, thanks for you contribution! Some thoughts: I would say compression should be done as last step before sending back the response to the client. I mean, we can take advantage of the AfterInvoke mechanism (attaching an handler or not according to Engine parameters). This should be more generally available to all MARS TMARSActivation implementation (only one in the official repository, I know). Another point is that some deployment methods (Apache/IIS) may provide compression natively and I would let this instead of our implementation. What about moving your implementation to the Server.Ignition unit (MARSTemplate demo)? See code below as draft... I guess one could even implement a symmetric BeforeInvoke to support compression also the other way around (from client to server), I don't know how this is popular/expected, however. Using Response.SetHeader may lead to multiple Content-Encoding headers to be set at the same time (TPrimitiveTypesWriter, in MARS.Core.MessageBodyWriters.pas for instance sets the Content-Encoding to provide some information about text encoding. This may be a mine misunderstanding however... I need to check this sooner or later... if anyone has something to say about this, please do!). I switched to setting the Response.ContentEncoding property as I was having trouble with Postman (and Chrome) when multiple Content-Encoding headers were set. // Compression if FEngine.Parameters.ByName('Compression.Enabled').AsBoolean then TMARSActivation.RegisterAfterInvoke( procedure (const AActivation: IMARSActivation) var LOutputStream: TBytesStream; begin if ContainsText(AActivation.Request.GetHeaderParamValue('Accept-Encoding'), 'gzip') then begin LOutputStream := TBytesStream.Create(nil); try ZipStream(AActivation.Response.ContentStream, LOutputStream, 15 + 16); AActivation.Response.ContentStream.Free; AActivation.Response.ContentStream := LOutputStream; AActivation.Response.ContentEncoding := 'gzip'; except LOutputStream.Free; raise; end; end; end ); Let me know what you think about. I would be glad to accept your PR then... Sincerely, Andrea
  7. Andrea Magni

    I have some questions.

    Hi @bioman, glad you sorted out in the meantime. The "FireDAC Basic" demo is the dataset-oriented (quite C/S+briefcase) way of handling data through MARS. I would suggest to have a look to EKON22 demo, specifically looking for the TRecord<R>.FromDataSet and the use of TMARSFireDAC there. Sincerely, Andrea
  8. Hi @Yaron, I don't have actual numbers about the most reliable/best performance deployment method but my preferred deployment method for production is having an internal MARS REST server (Windows Service or Linux Deamon) and Apache acting as a reverse proxy (implementing SSL, caching, compression, eventually load balancing). This grants quite some granularity with respect to performance tuning and service availability (you can restart a single service or the whole thing). I also have deployed some MARS servers as Apache modules (on Linux). A couple of customers are using MARS with IIS: one is using IIRF (basically making IIS a reverse proxy and SSL implementor), keeping MARS servers standalone (not even Windows Services though this is on the roadmap). The other one is using ISAPI deployment. I have news from time to time from people using the library and there is not a clear trend among available deployment methods. Sincerely, Andrea
  9. Andrea Magni

    I have some questions.

    Hi @bioman, there are several approaches to the topic (CRUD operation against a DB). MARS doesn't dictate one specifically. Would you please specify if you are building a Delphi to Delphi solution (Delphi on the client and Delphi on the server)? You can have a dataset-oriented approach (client asks for a dataset, modifies it, changes are sent back to the server in form of delta updates) or a more general record-oriented approach (client asks for data, server sends a JSON array, client makes POST or PUT calls with modified/new data records). It also matters if you are looking for a data-centric approach (i.e. sending whole records from DB to client and back) or more interpolated approach (client commands REST server to perform operations that results in data manipulation). MARS is a lightweight library and I am trying not to dictate some aspects (more related to application than library IMO) so there are many ways to use it. Thanks for the kind words! Sincerely, Andrea
  10. Andrea Magni

    COM server to MARS

    Hi, welcome to this forum and to MARS. I've worked in the past to some migration process from Datasnap to MARS (and from RemObjects to MARS too). One thing you could take advantage is that TMARSActivation class (quite the core of request / REST method execution matching) can be replaced / tweaked. This means you may change the way an http request is matched against the Delphi code to be executed to produce response. Or you may want to have a different strategy/parsing technology to fill REST method arguments from the request. Obviously this is not the easiest task in the world but may have a lot of sense especially on large projects (I've migrated large datasnap applications to MARS with minimal effort and reducing to the minimum changes in the methods code). Coming to your questions: 1) MARS can expose multiple engine (1 engine -> 1 port). Each engine can expose multiple applications. Each application can expose multiple resources. Each resource can expose multiple methods (http verbs and sub resources). You can organize resources as you like (one resource per unit, for example). I didn't get what you mean with "separate delphi project". You can deploy MARS server in several ways including ISAPI for IIS. 2) MARS serialization/deserialization mechanisms are designed to be pluggable so you can implement your own readers/writers to handle OleVariants as you prefer. 3) I have knowledge of MARS servers used in heavy load situations. Numbers are not significative because they actually depends on hardware/storage/purpose of REST methods. If you are looking for extreme performance, I would take a look to mORMot. But in 99% of my experience MARS is fast enough and REST architecture may help you to properly deal with scaling and performance boosts. Sincerely, Andrea
  11. Hi, thanks for the kind words and sorry for the delay. I guess you are referring to QueryParam like "sort" in http://localhost:8080/rest/default/query/EMPLOYEE?sort=LAST_NAME You can use the Required attribute to let MARS check for the parameter's existence before calling the REST method. function GetDataset([QueryParam, Required] sort: string): TFDQuery; I would add a specific value in the user's token, indicating the DB to use. You'll set this value in the token at authentication time (via API key or regular login). You can see this thread for a similar approach: Keep in mind that your situation (if you store the connection name to be used inside the user's token) it's easier as you can use a connection name like 'TOKEN_CLAIM_DBCONNECTION': [Context, Connection('TOKEN_CLAIM_DBCONNECTION', True)] FD: TMARSFireDAC; And MARS will expand that connection name to the value of the DBCONNECTION name stored in the Claims of your (JWT) token. If you need some fallback mechanisms or more dynamic behavior, follow the instructions in the "FireDAC Connections" thread I linked here above. Feel free to ask whatever you need, sorry for the delay in this reply but I am abroad with family (vacation time). Sincerely, Andrea
  12. Andrea Magni

    Unit 'JsonDataObjects' not found

    Hi @Rafael Mattos, MARS supports JsonDataObjects but does not include them (I am thinking about changing this...). You simply need to download JsonDataObjects (https://github.com/ahausladen/JsonDataObjects) and setup your library path to compile it. Then MARS' demo should work. Let me know please. Sincerely, Andrea
  13. Andrea Magni

    MARS, angular, firedac, json

    It turned out it was the wildcard in the Accept header to cause this. I just pushed a fix that should also apply to your case and you may no longer need to instruct the Accept header all the times. Branch: develop, link to the commit: https://github.com/andrea-magni/MARS/commit/b8d5768b65072ff403de3c60e17688e8e95b1d9a Sincerely, Andrea
  14. Hi @Stuart Clennett, you can add the IsReference attribute to instruct MARS not to free the object returned by the method (as it will be destroyed within the datamodule of course, as it is its owner). [GET/POST, IsReference] function GetAssessment(const id: string): TFDDataSet; Sincerely, Andrea
  15. Andrea Magni

    FireDAC Connections

    Hi @Stuart Clennett, I am happy you found a way to solve by yourself while I was in vacation 🙂 Your solution works but has a couple of things to consider: 1) that BeforeHandleRequest code gets executed for each incoming request (performance) 2) manipulating Parameters is not suggested as App.Parameters is like a global object (IIRC). You have an other opportunity through (yet another) undocumented MARS feature: [Context, Connection('Dynamic_MyConnection', True)] FD: TMARSFireDAC; The Connection attribute specifies the name of the connection definition to be used with the TMARSFireDAC instance injected. The name supports macros (the second argument enables macro expansion). You can rely on built-in macros (i.e. using some part of the token, params, username or similar things. A list is available here: https://github.com/andrea-magni/MARS/blob/a8d323558bd591589ef667eac326324302d167a9/Source/MARS.Data.FireDAC.pas#L528 ). Last chance of the macro-expander is looking for custom providers. You can register your own in the initialization of one of your units or in the Server.Ignition.pas file: TMARSFireDAC.AddContextValueProvider( procedure (const AActivation: IMARSActivation; const AName: string; const ADesiredType: TFieldType; out AValue: TValue) begin if SameText(AName, 'Dynamic_MyConnection') then begin if Odd(SecondOf(Now))then AValue := 'OddConnection_' + AActivation.Request.HostName else AValue := 'EvenConnection_' + AActivation.Request.HostName; end; end ); Beware: the connection name has to be this format: [PREFIX]_[SUFFIX](_[OTHER_SUFFIX]) Using 'MyConnection' won't work for instance... Pros of this approach: 1) code is executed only when needed (when the TMARSFireDAC instance gets created to be injected in your resources), all others REST endpoints won't be affected. 2) it seems more isolated to me (but this can be a personal evaluation). If you need to fix some TFDConnection instances on your datamodules, try having a TMARSFireDAC instance injected in the datamodule itself and use the FD.ConnectionDefName (already expanded once injected) to fix the ConnectionDefName of your components (OnCreate event of the datamodule should be fine, or AfterConstruction method as well). If you encounter troubles doing this, write here again: there's another hidden feature for you to fix this (when registering the datamodule as resource you can specify an anonymous method to initialize it or to call a custom constructor instead of TDatamodule.Create(AOwner)). Sincerely, Andrea
  16. Hi @Yaron, you can register an InvokeError procedure to deal with non-matching URLs, there's a template in Server.Ignition file, line 107 (https://github.com/andrea-magni/MARS/blob/daef64912b04036917cb336c4eee34438fa993a8/Demos/MARSTemplate/Server.Ignition.pas#L107). If you uncomment that registration, you can implement whatever policy using the AActivation argument to access Request and Response objects (you can set the StatusCode, Content and ContentType of the Response object as you like). Sincerely, Andrea
  17. I'm about to release TFormStand as a form-oriented twin of TFrameStand. To add support for TForm I had to refactor quite heavily TFrameStand code (now there is a common ancestor that is TSubjectStand and two inherited components TFrameStand and TFormStand). I am looking for: - people willing to test TFrameStand functionalities (regression tests) are still functioning; - people willing to test TFormStand Please reply to this message or contact me directly if you like to be involved. The new version is available in the TSubjectStand branch of TFrameStand GitHub repository: https://github.com/andrea-magni/TFrameStand/tree/TSubjectStand (Beware: uninstall any previous version of TFrameStand before installing the new one) Thanks Sincerely, Andrea
  18. Andrea Magni

    Looking for beta testers of TFrameStand and TFormStand

    Unfortunately not... The TFrameStand functionalities should be the same, there are some changes due to refactoring (i.e. if you had event handlers for TFrameStand events, some argument changed type like TFrameInfo<TFrame> now being TSubjecTInfo, so you may need to adjust them on your side). TFormStand is the same concept but supporting TForm instead of TFrame. If you already have projects using TFrameStand, it would be helpful if you could confirm I broke nothing. Sincerely, Andrea
  19. Andrea Magni

    Image from Form has no value

    Hi, yes the HTML form should be a multipart/form-data one... Glad you solved 😉 Sincerely, Andrea
  20. Andrea Magni

    Looking for beta testers of TFrameStand and TFormStand

    Great, please check out the new version from https://github.com/andrea-magni/TFrameStand/tree/TSubjectStand (you can use Git or download a zip file if you are not confident with Git). Just beware to uninstall any previous version of TFrameStand before proceeding. Some changes in your code may be needed especially if you used TFrameStand events. For example where you had TFrameInfo<TFrame> as event handler argument, now you'll find TSubjectInfo (that is a new superclass of TFrameInfo<T>). If you encounter issues, just drop me a line. Thanks. Sincerely, Andrea
  21. Andrea Magni

    Looking for beta testers of TFrameStand and TFormStand

    Thanks, I relocated the blog some time ago and I set up a rewrite rule that for some reason is not working well. I changed the links and updated also the demo list. That document will change again soon however, I'll add section for TFormStand soon. Sincerely, Andrea
  22. Andrea Magni

    Shortening the URL

    Hi @Yaron, you can definitely get rid of the "/rest" prefix by setting the Engine BasePath property to empty string (by default the engine has 'DefaultEngine' as Name and '/rest/ as BasePath): class constructor TServerEngine.CreateEngine; begin FEngine := TMARSEngine.Create; try // Engine configuration FEngine.BasePath := ''; // <============== FEngine.Parameters.LoadFromIniFile; // Application configuration FEngine.AddApplication('DefaultApp', '/default', [ 'Server.Resources.*']); If you want to push this thing futher, you can even think about inheriting your own TMARSActivation class and shortcut request matching by overriding FindMethodToInvoke method. HTH Sincerely, Andrea
  23. Andrea Magni

    Get Exception message on client

    Sorry, it's my fault: MARS supports two http layer implementor on the client side: Indy and TNetHttpClient. Handling errors has some differences across the two, so it depends if you are using a TMARSClient (Indy) or TMARSNetClient (TNetHttpClient). Either ways, you can define an OnError handler for your TMARSApplication: uses FMX.Dialogs , MARS.Core.Utils, MARS.Client.Utils , IdHttp; var LException: EMARSClientHttpException; LIdException: EIdHTTPProtocolException; begin if AException is EMARSClientHttpException then begin LException := EMARSClientHttpException(AException); ShowMEssage('Error' + LException.Message + ' Details: ' + StreamToString(LException.Content)); AHandled := True; end; if AException is EIdHttpProtocolException then begin LIdException := EIdHttpProtocolException(AException); ShowMEssage('Error' + LIdException.Message); AHandled := True; end; end; IIRC I was not able to find a way to collect error details (that are sent back from the server to the client using the body of the response) when using Indy. I am open to discuss how to improve the overall mechanism, please express your thoughts (everybody!). I'll try to update the old demos (such as HelloWorld) to include error handling at some point. Sincerely, Andrea
  24. Andrea Magni

    Datasnap -> MARS conversion

    Change TDataSet to TFDDataSet and you'll be able to produce both TMediaType.APPLICATION_JSON and TMediaType.APPLICATION_JSON_FireDAC (MARS will match what client prefer, looking for the Accept header's value): [POST] function GetData([BodyParam] AStatement: TStatement): TFDDataSet; function THelloWorldResource.GetData(AStatement: TStatement): TFDDataSet; begin Result := FD.SetName<TFDDataSet>(FD.Query(AStatement.SQL), AStatement.Name); end; Beware to remove the explicit Produces attribute you had. You may want to use a REST debugger (I like Postman) to make a call using Accept: application/json-firedac or Accept: application/json to see the two serializations. Now you can add a TMARSClientResourceJSON to your client application, note the SpecificAccept header where I am instructing to set Accept header to application/json-firedac media type: object MARSClientResourceJSON1: TMARSClientResourceJSON Application = MARSApplication SpecificAccept = 'application/json-firedac' SpecificContentType = 'application/json' Resource = 'helloworld' end Then use the following code (TMainDataModule is a datamodule containing the REST components, TMARSClient, TMARSApplication, TMARSClientResourceJSON): uses MARS.Core.JSON, MARS.Core.Utils, MARS.Data.FireDAC.Utils; procedure TMainDataModule.RetrieveData(const ASQL, AName: string; const AOnCompleted: TProc<TFDMemTable>; const AOnError: TProc<Exception> = nil); begin MARSClientResourceJSON1.POSTAsync( procedure (ABody: TMemoryStream) var LJSON: TJSONObject; begin LJSON := TJSONObject.Create; try LJSON.WriteStringValue('SQL', ASQL); LJSON.WriteStringValue('name', AName); JSONValueToStream(LJSON, ABody); finally LJSON.Free; end; end , procedure (ARes: TMARSClientCustomResource) var LData: TArray<TFDMemTable>; begin LData := TFDDataSets.FromJSON((ARes as TMARSClientResourceJSON).Response as TJSONObject); try if (Length(LData)>0) and Assigned(AOnCompleted) then AOnCompleted(LData[0]); finally TFDDataSets.FreeAll(LData); end; end , AOnError ); end; Then you can have a call like: MainDataModule.RetrieveData('select * from EMPLOYEE', 'Employee' , procedure (ADataSet: TFDMemTable) begin FDMemTable1.Data := ADataSet.Data; // cloning dataset end , procedure (AError: Exception) begin ShowMessage(AError.ToString); end ); FDMemTable1 is a TFDMemTable to store data on the client side. Please consider: 1) code could have been more simple than this but I wanted to include the fact this call is actually made asynchronously (so if you need to transfer a large dataset or connection is not very fast, you are not going to hang your client application); 2) this is a good example how to retrieve a dataset and then have a single (synchronized) point where the resulting dataset is then cloned to a local TFDMemTable that can be easily involved in databinding (LiveBindings) without being affected by the async call. Please let me know if this helps. Sincerely, Andrea
  25. Andrea Magni

    Datasnap -> MARS conversion

    TMARSFDResource is tightly coupled with a server side resource that has this interface: [GET, IsReference] function Retrieve: TArray<TFDDataSet>; [POST] function Update([BodyParam] const ADeltas: TArray<TFDMemTable>): TArray<TMARSFDApplyUpdatesRes>; One example of such resource is TMARSFDDataModuleResource (MARS.Data.FireDAC.DataModule.pas) that is the base class of the datamodule in FireDAC Basic demo. The logic of this resource does not allow the client to push statements to server (the Retrieve method is marked with GET verb so you don't have body available to send statements to be executed to sever side). Also, the Update method needs to know the structure (statements) of dataset in order to proprerly apply deltas to them. You can build a different resource on the same idea but adding statements as input to both methods. The Retrieve part we already covered in the previous message (using POST verb). You may want to have a PUT verb to apply updates. On the client side, you can use a TMARSClientResourceJSON and the TFDDataSets utility class (MARS.Data.FireDAC.Utils unit) to manage persistence of an array of datasets and/or an array of deltas (have a look at MARS.Client.FireDAC unit for some examples). As said, it is a bit unusual to send statements to be executed from the client to the server so there's no specific integration in MARS for this. It should not be hard to implement and all building blocks are already there. However if you find difficulties just write on this forum and I'll be happy to help. Sincerely, Andrea
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